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Nonobstetric Surgery during Pregnancy

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Obstetric Trauma

Anesthesia Core Program March 28, 2002

Dr. Peter Duffy

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Contents

NONOBSTETRIC SURGERY DURING PREGNANCY ...................................................4

What do you expect to encounter?............................................................................................... 4

How does pregnancy affect the surgical disease? ....................................................................... 4

What are the risks to the mother? ............................................................................................... 5

What anatomic/physiologic changes are important to consider when administering anesthesia for nonobstetric surgery? ........................................................................................... 5

What are the risks to the fetus?.................................................................................................... 8

Are anesthetics human teratogens? ............................................................................................. 8

What is the risk of preterm labor? .............................................................................................. 9

What effects does anesthesia have on the fetus?....................................................................... 10

When would you proceed with anesthesia and surgery? ......................................................... 11

How do the principles of obstetric anesthesia and nonobstetric anesthesia compare? ......... 11

What type of anesthetic is best? ................................................................................................. 11

What type of obstetric monitoring is necessary?...................................................................... 12

How do you manage a general anesthetic for a nonobstetric procedure in a pregnant patient? ......................................................................................................................................... 13

Summary ...................................................................................................................................... 14

ANESTHESIA FOR TRAUMA DURING PREGNANCY.................................................15

How common is trauma in pregnancy?..................................................................................... 15

What types of trauma are encountered? ................................................................................... 15

How does the pathophysiology of trauma differ in an obstetric patient? .............................. 15

What obstetric complications can be anticipated? ................................................................... 16

What are the fetal considerations? ............................................................................................ 17

What is important in the management of the pregnant trauma patient? .............................. 17

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Anything else important in anesthetic management? .............................................................. 19

How do you manage a maternal cardiac arrest? ...................................................................... 19

Appendix 1 – Study Abstracts .................................................................................................... 21

Appendix 2 - “ Guidelines for Laparoscopic Surgery during Pregnancy” ........................... 24

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Nonobstetric Surgery During Pregnancy

What do you expect to encounter? - Nonobstetric surgery occurs in up to 2% of all pregnancies. This is generally thought to be an

underestimate due to cases of unrecognised early pregnancy at the time of surgery. Despite this, routine pregnancy testing is not recommended and should be guided by the patient’s history.

- Surgery may become necessary during any stage of pregnancy. The most common surgical conditions among pregnant women include - trauma, ovarian cysts, appendicitis, cervical incompetence, breast masses, bowel obstruction, and gallbladder disease. Rarely, parturients present for complex neurosurgical or cardiovascular procedures. These procedures have been performed with favorable outcomes for mother and fetus even with controlled hypotension and cardiopulmonary bypass.

- My experience (in Canada) is that most nonobstetric surgery during pregnancy involves procedures for cervical incompetence. Technically, these procedures are not “nonobstetric surgery” but the same principles apply.

- A section of Health Canada’s website, http://www.hc-sc.gc.ca/pphb-dgspsp/rhs-ssg/index.html has links to Canadian information concerning infant and maternal mortality. “At approximately 4 maternal deaths reported for every 100,000 live births, Canada has one of the lowest maternal mortality ratios in the world, reflecting our universal access to high quality medical care, our healthy population, and the generally favourable economic and social status of Canadian women.” Specific Canadian data about morbidity or mortality related to nonobstetric surgery during pregnancy and obstetric trauma is not yet available.

- Anesthesia services may also be increasingly required for intrauterine fetal surgery, typically in the second or third trimester. Some specialized centers carry out fairly complex fetal surgery. However, the most common procedure at the Ottawa hospital is cordocentesis. This is also known as PUBS (percutaneous umbilical blood sampling). This is usually done to obtain fetal blood samples for detection of chromosomal abnormalities, various infectious diseases, and hematologic abnormalities. A similar procedure is also occasionally used for intrauterine fetal transfusion.

How does pregnancy affect the surgical disease? - Most pregnant patients are otherwise young and healthy and usually free of complicating

medical diseases. However, parturients are subject to the physiologic and anatomic changes of pregnancy and to the specific obstetric complications of pregnancy not seen in the general surgical population.

- The physiologic and anatomic changes of pregnancy can interfere with accurate surgical diagnosis. This is especially true for intraabdominal disease. The differential diagnosis of abdominal pain is more complex. For example, many gastrointestinal symptoms, abdominal tenderness, and leukocytosis (up to 15,000) are normal during pregnancy. Abdominal landmarks change progressively throughout pregnancy. Diagnostic procedures are often more difficult to carry out and interpret and in many instances (radiography) are avoided. About 1/3 of appendicitis diagnoses are incorrect, with a higher rate of misdiagnosis in later gestation. “Often, the correct diagnosis is determined only at operation.”

- Decisions concerning when to proceed with surgery may become difficult when the diagnosis is unclear. The surgical approach to intraabdominal disease is also affected. For example, laparotomy or laparoscopy? Location of incision? Gestational age, the nature of the surgical problem, the probability of correct diagnosis, and the surgeon’s experience all dictate the

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procedure to be done and the incision site selected. This will influence the choice of anesthetic and its management.

- The inherent delays associated with diagnosis and treatment decisions and potential misdiagnosis likely contribute to the increased maternal morbidity and mortality and fetal loss associated with nonobstetric surgery during pregnancy.

What are the risks to the mother? - The primary risk to the mother may be the surgical disease itself. This risk can be heightened

by misdiagnosis and delays in diagnosis attributable to pregnancy. - Besides contributing to diagnostic difficulties, the anatomic and physiologic changes of

pregnancy produce altered maternal responses to anesthesia and surgery. Of primary concern are alterations involving:

o Airway o Respiratory system o Cardiovascular system o Blood o Gastrointestinal system, and o Responses to anesthetic agents.

- Data from the 1970’s suggest significant maternal mortality rates in the range of 5-35%. I could not find more current data. However, these numbers reflect American data where trauma is the number one indication for nonobstetric surgery during pregnancy. Our influence is limited because the surgical diagnosis and the procedure are considered to have more impact on maternal mortality than the choice of anesthetic.

What anatomic/physiologic changes are important to consider when administering anesthesia for nonobstetric surgery? - Maternal changes during pregnancy are caused by hormonal alterations, mechanical effects of

the gravid uterus, metabolic demands of the fetoplacental unit, and hemodynamic alterations associated with the placental circulation. These changes generally become more significant as pregnancy progresses.

- Airway – Weight gain and airway capillary engorgement during pregnancy give rise to a

higher incidence of difficulty with mask ventilation and difficult intubation. Failed intubation is the leading cause of maternal death from anesthesia. A smaller than normal endotracheal tube (e.g. 6.5 mm) may be necessary. Nasotracheal intubation and insertion of other nasal tubes (e.g. nasogastric tubes, temperature probes) should be avoided.

- Respiratory - Pulmonary flows are essentially unchanged and measures of both large and small airway functions are normal in pregnancy. However, respiration becomes mainly diaphragmatic because of the elevated diaphragm and limitation of thoracic cage expansion. The lack of ability to use accessory muscles may be problematic in patients with respiratory disease. The ability to cough after administration of regional anesthesia is even more impaired in pregnant patients. Hypoxia develops more rapidly in pregnant women than in non-pregnant women during hypoventilation or apnea. Several factors are involved here. Increased oxygen consumption leads to a faster decline in PaO2 when ventilation is decreased. Reduced FRC allows for more rapid denitrogenation during preoxygenation but also provides a smaller oxygen reserve. As

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well, closing capacity is unchanged. The resulting decrease in the FRC/CC ratio leads to a more rapid small airway closure when lung volume is reduced. In fact, FRC is less than CC in up to 50% of pregnant women in the supine position. Preoxygenation occurs more quickly but once preoxygenated, parturients will desaturate about twice as fast as non-pregnant women during a rapid sequence induction. The threshold for the use of supplemental oxygen should be lowered in pregnant patients receiving regional anesthesia or sedatives. Controlled ventilation during general anesthesia should be adjusted to maintain a PaCO2 of about 30 mmHg. The maternal PaCO2 is reduced to 30 mmHg by 12 weeks of pregnancy and remains at this level. When adjusting the ventilation remember that the normal gradient between PaCO2 and end-tidal CO2 is diminished during pregnancy because of the reduction in alveolar dead space from increased cardiac output (pulmonary perfusion). Normal arterial blood gases during pregnancy will show a small increase in O2 and a decrease in CO2 with partial metabolic compensation. The rate of inhalational induction of general anesthesia is increased in pregnant patients. Respiratory changes specifically increase the rate of rise of FA/FI. This is due to the combination of increased minute ventilation and reduced FRC. These changes are greater than the opposite effect achieved by increased CO. Reduction in MAC also contributes.

- Respiratory Summary: o Difficult mask ventilation and intubation o Avoid nasal tubes o Loss of accessory muscles and decreased ability to cough under regional anesthesia o Rapid onset of hypoxia during hypoventilation and apnea primarily due to reduced

FRC and increased oxygen consumption o Compensated respiratory alkalosis with reduced PaCO2 to end-tidal CO2 gradient o Increased rate of inhalational induction.

- Cardiovascular - The primary cardiovascular change of concern is aortocaval compression

(ACC). Although caval compression is detectable somewhere around 13-16 weeks gestation, ACC doesn’t become significant until the second half of pregnancy (i.e. from about twenty weeks onward). Measures of fetal and neonatal wellbeing deteriorate when the mother is supine during labor. For example, fetal pH, fetal pO2, incidence of late decelerations, umbilical cord pH, and Apgar scores all deteriorate with ACC. Adverse effects from ACC can be prevented by full lateral position. When that is not possible, left uterine displacement and left-sided tilt (wedge) should be used. If the uterus is especially large (twins, polyhydramnios, macrosomia, etc.), extra tilt may be necessary (e.g. 30o). Chronically increased venous pressure during pregnancy can lead to hemorrhoids and increased pelvic venous distension. This may increase bleeding during nonobstetric surgery and predispose the parturient to venous thromboembolism. Epidural venous plexus distention increases the risk of intravascular placement of an epidural catheter and reduces the capacity of epidural space. This reduced capacity increases the spread of epidural local anesthetic and reduces dose requirements. Patients with pre-existing cardiovascular disease may decompensate during pregnancy because of these physiologic demands. This is especially true for patients with stenotic valvular lesions.

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Altered responses to chronotropic and pressor agents also have anesthetic implications. Decreased response to beta-agonists makes them less reliable as markers of intravascular injection during the test dose of epidural anesthesia. Since pregnancy increases dependence on the sympathetic nervous system for maintenance of venous return, the parturient will require more volume replacement to maintain BP in the face of vasodilation from regional anesthesia. As well, ephedrine is particularly well suited to treat hypotension secondary to regional anesthesia because of its venoconstrictor properties. Alpha-agonists will be less effective and can directly decrease uterine blood flow.

- Cardiovascular Summary: o Aortocaval compression o Increased venous pressures – venous bleeding, thromboembolism, epidural venous

distention o Decompensation with preexisting cardiovascular diseases o Altered responses to vasoactive medication.

- Blood – Expansion of maternal blood volume in excess of the increases in red blood cell

volume produces a dilutional anemia. Tissue oxygen delivery is maintained by the increase in CO. Reduced blood viscosity is thought to be beneficial to uteroplacental perfusion. Mothers are able to tolerate moderate blood loss but this pre-existing anemia decreases the parturient’s reserve during more significant hemorrhage. The hypercoagulable state also increases the parturients risk of venous thrombosis. Given the chronic venous obstruction associated with caval compression, the lower limbs are most susceptible. Pregnancy is associated with a benign leukocytosis making WC count an unreliable marker of infection.

- Gastrointestinal - Pregnancy increases the mother’s risk of aspiration during administration

of anesthesia. This is due to a reduction in barrier pressure (difference between intragastric pressure and lower esophageal sphincter tone) secondary to hormonal and mechanical factors. Pregnant patients should always be managed as patients with a “full stomach” but the gestational age at which this risk becomes significant is not well defined. Hormonal changes occur early in pregnancy whereas the mechanical effects occur later. Patients with a history of reflux during their pregnancy are a greater risk. As a general guideline, you should consider any patient at 18-20 weeks or greater at risk.

- Responses to anesthetic agents:

o MAC for volatile anesthetics is reduced. Suggested mechanisms include: sedative effect of progesterone; increased CNS serotonergic activity; and increased beta-endorphins.

o Pregnancy increases the sensitivity to sodium thiopental. This sensitivity is similar to that seen with volatile anesthetics; the induction dose is decreased by about one-third. Although the clearance of pentothal is increased, its elimination half-life is prolonged because of a higher volume of distribution. Doses of 4 mg/kg or less have been shown to have minimal impact on the fetus or newborn. Propofol has not been studied as extensively as thiopental. Doses greater than 2 mg/kg have been shown to produce significant neonatal depression. More research is needed. Ketamine can increase uterine tone and endanger the fetus when given in large doses (~2 mg/kg)

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during the first and second trimesters. The effect on uterine tone becomes insignificant by the third trimester.

o Pregnancy increases neural susceptibility to local anesthetics. The exact reason for this is not clear. It could represent a pharmacodynamic change with increased receptor sensitivity. It may also be due to greater local anesthetic access to the intraneural site of action. Penetration could be enhanced by reduced cerebrospinal fluid (CSF) protein concentration (↓ binding) or by elevated cerebrospinal fluid pH (BH+ → B). As discussed above, the capacity of the epidural space is also reduced.

o Pregnancy is associated with a reduction in plasma cholinesterase levels. However, succinylcholine neuromuscular blockade is not prolonged because of increases in volume of distribution.

What are the risks to the fetus? - The surgical disease and its nonsurgical treatment may have significant detrimental effects

on the fetus. - Teratogenesis of anesthetic agents has been a major concern that is not supported by

available evidence. However, nonobstetric surgery during pregnancy is associated with an increased risk of fetal loss, perinatal mortality, and IUGR.

- Nonobstetric surgery during pregnancy has also been associated with an increased risk of preterm labor.

- Anesthesia and surgery may have both direct and indirect effects of on the fetus. Of particular concern here are intraoperative disruptions in uteroplacental perfusion and fetal oxygenation.

Are anesthetics human teratogens? - Teratogenicity can be defined as “any significant postnatal change in function or form in an

offspring after prenatal treatment.” Functional or structural abnormalities can result depending on the gestation at which exposure of occurs. Most structural abnormalities result from exposure during the period of organogenesis (31-71 days after LMP). Teratogens may also lead to early fetal loss, which goes undetected or undiagnosed. Up to 80% of human conceptions are not carried to delivery.

- Prospective clinical trials involving humans are not practical, so research has focused on lab and animal studies, surveys of operating room and dental personnel occupationally exposed to waste gases, and reports of parturients undergoing nonobstetric surgery and anesthesia.

- Available evidence demonstrates that anesthetic agents can interfere will cellular events such as DNA synthesis and cell division. Further, some anesthetic agents have been shown to be teratogenic in animals. Chronic exposure surveys have also suggested an increased incidence of malformations and fetal loss. Finally, studies of nonobstetric surgery during pregnancy have failed to show any increase in congenital anomalies but have shown higher incidences of fetal loss, perinatal mortality, and IUGR.

- Interpreting this research is fraught with problems. Why? There is no data to link known effects on mammalian cells to teratogenicity. Animal data is not necessarily applicable to humans (see Shepard’s Catalog of Teratogenic Agents). Dose and timing of administration of potential teratogens is crucial to their effects. Small doses, which cause effects during the period of organogenesis, may be harmless to the older fetus, even in larger doses. Chronic exposure to small doses of an anesthetic may not equate with a short exposure to a larger dose. Results must also be interpreted against the general background risk of malformations,

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which stands at about 3%. Further, much of the available data is quite dated and is often retrospective. Finally, we must consider the negative outcomes after nonobstetric surgery.

- Several large and many smaller reviews of nonobstetric surgery during pregnancy have variously show increased risks of fetal loss, perinatal mortality, and growth restriction. Three of the larger studies often quoted are by Mazze and Kallen (1989), Duncan et al. (1986), and Brodsky et al. (1980). The abstracts of these are included in the appendix. Specific numbers about the various risks (the kind you can quote to patients) are hard to generate from these papers. For example, Brodsky found an increase in first trimester fetal loss after nonobstetric surgery during pregnancy of 2.9% (5.1% vs. 8%). Mazze, on the other hand, found no increased risk of fetal loss. All we can really say is that these risks do exist but that the increase in risk compared to parturients who are not undergoing nonobstetric surgery is a relatively small. Most of the larger studies and many of the smaller ones are retrospective reviews that cannot elucidate etiologies for the outcomes they detect. “As in most studies, it is difficult to separate the effects of the anesthetic technique from that of the surgical procedure.” In these reviews, no particular type of anesthesia or anesthetic agent could be identified as a preventative or causal factor. The etiological role of anesthesia in these events is thus not clear. In clinical practice, outcome is probably more dependent upon the underlying surgical condition and the surgical procedure.

- There are some reports that suggest a small increase in the incidence of cleft palate/lip associated with diazepam use during the first trimester of human pregnancies. However, a review of all available data does not confirm diazepam as a human teratogen. Despite this, chronic therapy is usually avoided during pregnancy. From our viewpoint, there is no evidence to support avoiding single-dose benzodiazepines during anesthesia, even in the first trimester.

- Nitrous oxide has been linked to spontaneous abortion and congenital anomalies in animal studies and some older epidemiologic surveys (chronic occupational exposure in operating room and dental personnel). The risk to humans has been disputed by critical review of this data and more recent research. “Overall, the epidemiologic data do not support an increased risk of congenital anomalies with chronic exposure to nitrous oxide.” The conservative approach is to limit N2O during the period of organogenesis, restrict it to a maximum of 50%, and limit its use in long cases.

- Bottom line - There is no evidence to show teratogenic effects in the human fetus from any anesthetic agent or drug routinely used during anesthesia (the individual drug classes are extensively discussed in Chestnut Chapter 16). The incidence of congenital anomalies is not increased by nonobstetric surgery and anesthesia during pregnancy, regardless of the anesthetic technique used. Fetal loss, perinatal mortality, and IUGR are increased after nonobstetric surgery but it appears these outcomes are not influenced by the choice of anesthetic (as long as the maternal condition and uteroplacental perfusion are optimized of course).

What is the risk of preterm labor? - Epidemiologic studies of nonobstetric surgery during pregnancy have also demonstrated an

increased risk of preterm labor and delivery. Mazze showed an increase from 5.13% to 7.4% when a parturient undergoes surgery.

- The exact etiology is not clear but abdominal surgery, especially with uterine manipulation, is considered to be a risk factor. Traumatized myometrium can release prostaglandins capable of stimulating labor. Procedures in the second trimester carry the lowest risk with the highest risk in the third trimester.

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- Myometrial depression caused by volatile anesthetics has been considered beneficial, potentially reducing the likelihood of preterm labor. However, “…no single anesthetic agent or technique has been found to be associated with a higher or lower incidence of preterm labor.”

- The use of prophylactic tocolysis remains controversial accept in cases of fetal surgery. Beta-agonists, magnesium, and indomethacin may have anesthetic implications.

- Toco monitoring for preterm labor and early tocolysis usually prevents fetal morbidity.

What effects does anesthesia have on the fetus? - Anesthesia may have direct and indirect effects on the fetus. - The direct depressant effect of anesthetic agents on the fetal nervous and cardiovascular

systems is usually of little concern unless the fetus will be delivered during the procedure or shortly afterwards. In such cases, the neonatologist should be informed. There are suggestions in the literature that high anesthetic concentrations and/or prolonged administration could have adverse effects on the fetus but I could not find hard data. Reduced beat-to-beat variability, indicating an anesthetized fetus, is common after administration of induction agents and opioids. It has been suggested that acetylcholine released after administration of anticholinesterases may increase uterine tone precipitating premature labor. The slow administration of the anticholinesterase after prior administration of the anticholinergic has been recommended. Glycopyrrolate is recommended because, unlike atropine, it does not cross to the placenta. Atropine can cause decreased variability and fetal tachycardia.

- Indirect effects are of greater importance and result from alterations in the maternal condition during anesthesia.

o Maternal hypoxia – Any intraoperative event that reduces maternal oxygenation is a potential risk to the fetus.

o Maternal hyperoxia – Intraoperative hyperoxia does not carry any risk for the fetus. Uteroplacental vasoconstriction, intrauterine retrolental fibroplasia, and ductus arteriosis closure do not occur. Fetal PaO2 never exceeds 60 mmHg, even with high maternal PaO2’s. Pregnancy doesn’t even contraindicate emergency hyperbaric oxygen treatment (PaO2>2000 mmHg). Over 700 cases of parturient HBO treatments have been reported at all stages of gestation without any adverse fetal effects. Scuba diving is contraindicated however.

o Although maternal hypercarbia can cause fetal acidosis with subsequent fetal myocardial depression and hypotension, maternal hypocarbia is of greater concern. Maternal alkalosis can compromise fetal oxygenation by causing umbilical artery constriction and a left-shift in the maternal oxyhemoglobin dissociation curve. Hyperventilation can also reduce cardiac output, decreasing uterine blood flow, independent of changes in PaCO2. Maternal hyperventilation should be avoided and the maternal PaCO2 should be kept in the normal range for pregnancy (around 30 mmHg).

o Uteroplacental perfusion can be adversely affected during nonobstetric surgery. Maternal hypotension from excessive anesthesia, aortocaval compression, hypovolemia, or blood loss will directly reduce uterine perfusion pressure. Remember, uterine perfusion is not autoregulated. Other intraoperative factors, which can impair uteroplacental perfusion, include alpha-adrenergic agents, excessive plasma levels of local anesthetics, and high levels of circulating catecholamines from preoperative anxiety or insufficient anesthesia. These factors can cause uterine artery vasoconstriction and uterine hypertonus. Uterine hypertonus

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reduces uteroplacental perfusion by increasing uterine vascular resistance. In the first 2 trimesters, ketamine in the high doses can also increase uterine tone.

When would you proceed with anesthesia and surgery? - With the exception of procedures for cervical incompetence, elective surgery should not be

performed during pregnancy. - Ideally, urgent surgery should be avoided during the first and third trimesters when possible.

The first trimester includes the period of organogenesis with risks of teratogenicity and fetal loss. Surgery in the third trimester it is associated with a higher risk of preterm labor. The physiologic and anatomic changes of pregnancy are also greater in the third trimester increasing the potential risk to the mother from surgery and anesthesia.

- Urgent procedures should be performed without delay and timing is primarily dictated by the surgical condition. Serious maternal illness presents greater risks to the fetus than the remote risks associated with anesthesia and surgery. Preserving maternal health is the best way to maintain fetal health so necessary surgery should not be delayed.

- Decisions concerning simultaneous cesarean section depend on numerous factors including the gestational age, fetal viability, surgical condition, nature of the surgery, risk to the mother of a future trial of labor, intraabdominal sepsis, etc.

How do the principles of obstetric anesthesia and nonobstetric anesthesia compare?

Obstetric analgesia/anesthesia Nonobstetric anesthesia Pain free delivery for mother Effective surgical anesthesia for

mother and fetus Do not depress uterine activity Do not stimulate uterine activity Maintain labor Do not stimulate labor Maternal effect while minimizing fetal effects

Little consideration for fetal respiratory depression or sedation

Maintain uteroplacental exchange Maintain uteroplacental exchange

What type of anesthetic is best? - Does it matter? For the fetus? For the mother? - As far as the fetus is concerned… “Intraoperatively there is no evidence that any anesthetic

technique is better than any other as long as maternal oxygenation and perfusion are maintained.” “No study has correlated improved fetal outcome with any anesthetic technique.”

- As far as maternal safety is concerned, regional/local anesthesia or MAC are usually regarded as safer than GA, especially iun the 3rd trimester. This stems from reports of maternal morbidity and mortality that consistently show airway concerns topping the list of anesthesia-related problems.

- Local/Regional/Neuraxial anesthesia also minimizes fetal drug exposure and may allay parental concerns about fetal effects and teratogenicity. Spinal anesthesia in particular, exposes the fetus to insignificant amounts of drug.

- Despite the foregoing, anesthetic choice is most often determined by considerations such as the surgical disease and nature of the procedure being performed.

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- Bottom line – Minimize anesthesia intervention while providing adequate anesthesia and analgesia any standard technique. Generally, the lowest effective dose is preferred in all instances (the emphasis on effective). Avoid hypoxia, hypotension, hyperventilation, and acidosis striving to maintain uteroplacental perfusion.

What type of obstetric monitoring is necessary? - Continuous fetal heart rate (FHR) monitoring is usually quoted as possible at 16 weeks. In

practical terms however, continuous external FHR monitoring is generally not feasible until ~18-22 weeks gestation. Baseline FHR is about 120-160 and FHR variability is generally not seen until 25-27 weeks’ gestation. Changes in baseline FHR and FHR variability must be interpreted considering the affects of drugs administered during anesthesia. Uterine pressure monitoring (tocodynamometry) is not really feasible until the uterus is above the umbilicus (at least 22-24 weeks). Toco is most useful for detecting premature labor in the later stages of pregnancy and tends to work better in multips than primips. An experienced nurse can palpate contractions at about 20 weeks. Obesity and location of the surgical incision may make external FHR/toco monitoring impossible. Intermittent intraoperative ultrasound monitoring is an alternative. I have also heard of the transvaginal route being used.

- Does the literature support FHR monitoring during nonobstetric surgery? A study by Horrigan et.al. in the Journal of Perinatology in 1999 concludes “Twenty years’ experience has yielded no documented evidence that obstetric personnel are required to monitor FHR changes during nonobstetric surgical procedures.” A followup letter rebuts this conclusion by citing additional studies and numerous cases where intraoperative monitoring of FHR and uterine pressure prompted intervention. A further commentary states - “The major risks to the fetus during maternal surgery are those of hypoxia and preterm delivery. Intraoperative monitoring does have the potential…to detect adverse maternal conditions before they are apparent with routine maternal monitoring. Whether detection and correction of FHR changes or uterine activity intraoperatively will ultimately affect fetal outcome or prevent preterm delivery, has not to been proven, but has been suggested.” “Individualization of intraoperative monitoring appears to be a reasonable approach in the absence of further data in this area.” Definitive recommendations cannot be supported by the available literature.

- Practical application: o FHR/toco monitoring should be individualized for each case. If technically feasible,

and if it doesn’t interfere with the surgery, continuous perioperative monitoring is ideal. At a minimum, preop and postop readings should be recorded when possible.

o Someone capable of interpreting the FHR tracing should be present when monitoring occurs. A trained obstetric nurse is a good option.

o FHR changes may be a direct result of administered drugs. For example, opioids cause a reduction in beat-to-beat variability and atropine causes tachycardia.

o A plan for dealing with FHR abnormalities considering fetal viability should be discussed preoperatively. The obstetric team obviously needs to be involved.

o The greatest value of FHR monitoring is that it allows the early detection of problems with fetal oxygenation that may be amenable to optimization of the maternal condition. “An unexplained change in FHR mandates the evaluation of maternal position, blood pressure, oxygenation, and acid-base status and inspection of the surgical site to ensure that neither surgeons nor tractors are impairing uterine perfusion.” “This is a medical issue not a medico-legal one!”

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o Monitoring for FHR abnormalities and premature labor (toco) should continue into the postop period. The duration of this monitoring is the debatable and often individualized.

How do you manage a general anesthetic for a nonobstetric procedure in a pregnant patient? - Preop assessment

o OB consult – fetal viability, plan, monitoring. o What do you tell the patient?

Will the anesthetic harm my baby? Tell me what drugs you are going to use and what effects they have? “I heard…”, “I read on the Internet…” etc.

A primary function of the preoperative assessment is to provide maternal reassurance and allay anxieties. You can reassure mom that anesthetic agents do not increase the risk of congenital malformations. Reviews do suggest increased risk for fetal loss, perinatal mortality, and preterm labor. However, these risks remain small and are not affected by the anesthetic choice. The planned use of fetal monitoring may also alleviate some anxiety.

o Anxiolytic premedication can be used as necessary. o Order antacids for aspiration prophylaxis (Ranitidine, Na Citrate).

- Drugs o Any of the commonly used anesthetic agents can be given in the perioperative period

as a long as the parturient’s condition is kept as a stable as possible and fetal oxygenation is optimized. For example, if alpha agonists are necessary to maintain maternal CV stability then they should not be avoided (e.g. mitral stenosis).

- Positioning o Aortocaval compression o Prone contraindicated o Before and after – full lateral.

- Monitoring o FHR/toco as discussed. o ETCO2 vs PaCO2 – Gradient is decreased. o Art line – Gases, beat-to-beat BP.

- Induction o Usual drugs, minimize dose o RSI at 18 weeks and beyond or earlier if GI symptoms.

- Maintenance o A high FIO2 is warranted. o N2O need not be avoided. The conservative approach is to limit N2O during the

period of organogenesis, restrict it to a maximum of 50%, and limit its use in long cases.

o Maintain normal cardiorespiratory status. Use FHR when possible. o Avoid hyperventilation, remember the respiratory alkalosis and the reduced ETCO2-

PaCO2 gradient. Keep the pCO2 normal for pregnancy (~30). o Good abdominal relaxation can help to minimize uterine handling, which may reduce

likelihood of preterm labor. - Emergence

o Reversal as discussed previously. Anticholinergic first followed by the anticholinesterase.

- Postop

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o Continue FHR/toco monitoring – consider effects of opioids on FHR variability. o Analgesia - Responses to poor analgesia can compromise the fetus. o Position on side. o Venous thrombosis prophylaxis may be given.

Summary - Anatomic and physiologic changes complicate surgical assessment and treatment. - Surgical diagnosis may be more difficult but should not be unduly delayed because of

pregnancy. - Maternal risk is primarily due to the surgical disease. Maternal anesthesia related risks may

be increased secondary to the changes of pregnancy. - Anesthetics do not increase the rate of congenital anomalies associated with cases of

nonobstetric of surgery during pregnancy. - The primary risks to the fetus include fetal loss, perinatal mortality, growth restriction, and

preterm labor. The causes of these outcomes are unknown and the risks are not modifiable by anesthetic choice.

- Anesthesia may have both direct and indirect effects on the fetus. Consideration of these will affect anesthetic management.

- Urgent procedures should not be unduly delayed but surgery is ideally done during the second trimester. Appropriate and timely treatment of the surgical disease is the best way to protect the fetus.

- The choice of anesthetic is governed by surgical factors but its administration is influenced by obstetrical factors. Evidence suggests that any of the commonly used anesthetic agents can be safely administered during nonobstetrical surgery as long as uteroplacental perfusion and fetal oxygenation are maintained.

- The primary goal of anesthetic management is to maintain uteroplacental perfusion through avoidance of hypotension, hypoxia, hyperventilation, and acidosis.

- Intraoperative FHR/toco monitoring should be used when technically feasible (e.g. >18 weeks).

“ Guidelines for Laparoscopic Surgery during Pregnancy” Defer surgery until 2nd trimester. Use intermittent pneumatic compression devices to prevent thrombosis in the lower

extremities. Monitor fetal and uterine status and maternal ETCO2 and ABGs. Use an open technique to enter the abdomen. Avoid ACC. Maintain low pneumoperitoneum pressures (< 15 mmHg). Obtain preoperative obstetric consultation.

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ANESTHESIA FOR TRAUMA DURING PREGNANCY

How common is trauma in pregnancy? - Trauma is the leading cause of death in youth and women of childbearing age are included in

the at-risk population. - Approximately 5-10% of all parturients suffer some form of trauma-related injury during

pregnancy. The incidence of trauma increases with each trimester. - Trauma is currently the number one nonobstetric cause of maternal mortality in the US. By

some accounts, trauma is “the most frequent cause of maternal death the United States of America.” I don’t think these rates apply to Canada, especially considering our lower rates of violent trauma. The Canadian Perinatal Surveillance System (CPSS) under the auspices Health Canada is conducting a study into maternal mortality and morbidity. This study is looking at cause-specific death rates associated with pregnancy. This will include “comparisons of rates of suicide, homicide and other traumatic causes.”

- Trauma-related maternal mortality has been steadily rising while obstetric causes of maternal mortality have been on the decline for years.

What types of trauma are encountered? - Again, most of the data is from the US where the incidence of violence-related trauma is

substantially higher than Canada. - The primary causes of trauma involving the pregnant patient include:

o Violence (including suicides) o MVAs o Falls, and o Burns.

- Trauma is often classified as blunt vs. penetrating. Blunt obstetric trauma most often involves MVAs and falls. Penetrating obstetric trauma is much less common and usually involves stabbing or gunshots to the abdominal area during the latter stages of pregnancy. It is interesting to note that with penetrating abdominal trauma, fetal mortality is very high (up to 70%) while maternal mortality is quite low (< 5%). This probably relates to the enlarged uterus, amniotic sac, and fetus taking the brunt of the injury while the displaced maternal organs are preserved.

- The incidence of trauma increases with each trimester. Most mortality is caused by head injury and hemorrhagic shock.

- Parturients may be at increased risk of trauma for several reasons. Pregnancy induces changes such as fatigue, anemia, altered gait (weight distribution, ligamentous laxity), fainting, and protuberant abdomen. For various domestic and social reasons, pregnancy may be a direct cause of violent trauma. Current day parturients also maintain more active lifestyles throughout pregnancy.

How does the pathophysiology of trauma differ in an obstetric patient? - As with all obstetric cases, evaluation and resuscitation considerations involve 2 patients.

The relative severity of injury to each may vary, but in all cases significant injury to the mother will also compromise the fetus.

- The parturient and the fetus can suffer direct tissue injury from blunt trauma, penetrating trauma, or burns. The parturient may suffer indirect tissue injury from associated hemorrhagic shock and other complications such as DIC, ARDS, sepsis, etc. Maternal injury

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may also compromise fetal oxygenation. This may be direct through interruption of uteroplacental flow or indirect through uterine hypoperfusion or hypoxia.

- As with surgical disease, the anatomic and physiologic changes of pregnancy will complicate assessment and management of the trauma victim. Here to, pregnancy can alter the location and pathophysiology of maternal injuries.

- Pathophysiology specifics: o The normal cardiovascular changes associated with pregnancy “may complicate the

evaluation of intravascular volume, the assessment of blood loss, and the diagnosis of hypovolemic shock.” Any judgment regarding the adequacy of maternal blood flow must be made with an understanding that baseline flow is substantially increased. This relative hypervolemia (and hemodilution) may afford some protection from the affects of hemorrhage, but there is a downside. Parturients will not show signs of hypovolemic shock until significantly greater volumes of blood (~40%) are lost as compared to nonpregnant trauma victims (~20%). As well, apparent maternal hemodynamic stability may not reflect adequate uteroplacental profusion and fetal oxygenation. The uteroplacental unit is one of many parallel maternal tissue beds competing for diminishing available oxygen. This vascular pathway has no ability to autoregulate and is easily constricted by high catecholamine levels (stress response, pain) and flow redistribution during shock.

o The parturient’s buffering capacity is reduced due to compensation for the normal respiratory alkalosis and by the reduced hemoglobin of pregnancy. Therefore, the ability to withstand hypoperfusion-associated acidosis is reduced.

o Dilutional anemia must be considered when assessing hemoglobin and leukocytosis when assessing white counts.

o Anatomic changes also impact the pathophysiology of injury. Significantly increased hemorrhage may result from pelvic injury (particularly pelvic fracture) due to the increased vascularity of this area associated with pregnancy. This is true even in the first trimester. Distortion of the abdominal anatomy, as the uterus ascends into the addominal cavity during pregnancy, causes variability in the anatomic pattern of abdominal injury. As mentioned this may be somewhat protective for the mother. Retroperitoneal hemorrhage is more frequent and more severe in the pregnant patient than in nonpregnant patients.

What obstetric complications can be anticipated? - The primary obstetric complications in the traumatized parturient include:

o Preterm labor o Premature rupture of membranes (PROM) o Uterine rupture o Placental abruption o Post-traumatic spontaneous abortion.

- Preterm labor can be stimulated when the injured myometrium releases prostaglandins. Premature rupture of membranes (PROM) can also stimulate preterm labor as well as increasing the risk of infection. Uterine rupture is rare but results in 10% mortality for the parturient and is almost universally fatal for the fetus. Placental abruption is more likely with more severe trauma and occurs in up to 50% of major trauma cases. “Except for maternal death, placental abruption is the most frequent cause of fatal death after trauma.” Abruption is also associated with significant maternal hemorrhage and coagulopathy/DIC. Abruption may be present even in the absence of external signs of abdominal injury or history to suggest direct abdominal injury. The first-line diagnostic test for abruption is ultrasound. However, a

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FHR tracing indicating fetal distress is probably more sensitive. For this reason, a minimum period of 4 hours of continuous FHR monitoring after trauma is recommended. Any tracing abnormality or suggestive signs/symptoms mandate a longer period of monitoring.

What are the fetal considerations? - The effect of trauma on the fetus will depend upon the gestational age, the type and severity

of maternal injury, the presence of direct blunt or penetrating fetal injury, and the extent of disruption of normal uterine and fetal physiology.

- The most common cause of fetal death is maternal death. Other common causes of fetal demise include abruption, maternal shock, and direct fetal trauma.

- Direct fetal injury can occur with penetrating trauma, such as stabbing and gunshots. Fetal mortality is generally high. Direct fetal trauma from blunt injury occurs most commonly in the third trimester when the fetal head has entered the pelvis. Skull fracture with intracerebral hemorrhage can result.

- Indirect fetal injury occurs when maternal injury interferes with adequate uteroplacental perfusion and fetal oxygenation. Remember that the maternal side of the circulation is not autoregulated. Hypotension and peripheral vasoconstriction associated with hemorrhage and catecholamine release directly reduce flow. Direct injury to uterine perfusion is also possible, particularly with penetrating trauma.

- We must also consider the effects of nonobstetric surgery and anesthesia on the fetus, as previously discussed, when operative procedures are undertaken.

- Fetal evaluation occurs as part of the secondary survey. Continuous FHR monitoring of the viable fetus should be instituted, even in the absence of signs of abdominal injury. The duration of post-trauma fetal monitoring is controversial. Monitoring is enhanced with continuous tocodynamometry and intermittent ultrasound. Contractions caused by myometrial release of prostaglandins, often subside spontaneously. Tocolytic therapy may be indicated.

- The fetal evaluation should include a determination of fetal viability. “The fetus is considered viable when it has a 50% chance of extrauterine survival.” With the availability of appropriate neonatal care, a 50% chance of survival typically exists at about 25-26 weeks or 750 grams. Some centers go as low as 24 weeks or 500 grams. A very rough guide in the ER is fundus over umbilicus (the fundus typically reaches the umbilicus at 20 weeks).

What is important in the management of the pregnant trauma patient? - The anesthesiologist may be involved in the entire continuum of trauma care for the obstetric

trauma victim. We may be involved in the initial resuscitation, preoperative assessment, perioperative care, and on an ongoing basis for airway issues and analgesia.

- Prehospital care providers can alert you to want to expect. Adequate preparation can then be made. Part of that preparation is assembling the appropriate staff (in our case, the “trauma code” system).

- RULE # 1 - The ABC’s of trauma resuscitation remain unchanged. The usual BLS, ACLS, and ATLS guidelines should be applied regardless of the pregnancy. The first priority is to stabilize the mother’s condition.

- RULE # 2 – Maternal Resuscitation = Fetal Resuscitation. - Primary Survey – Assess the airway/c-spine, breathing, and circulation as usual. Early

supplemental oxygen and avoidance of aortocaval compression are essential. Hypovolemia should be suspected before it becomes apparent. Aggressive volume resuscitation is usually recommended.

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- Secondary Survey – A complete history (including the obstetric history) should be obtained. The complete physical exam should include an assessment of the fetus (including FHR/toco and ultrasound). The impact of pregnancy on the nature of the injury should be considered.

All of the usual concerns about the anatomic and physiologic changes of pregnancy obviously apply. Below are some specific details relevant to the traumatized parturient.

- The serious trauma victim will typically need the airway secured with the attendant difficulties and heightened aspiration risk associated with pregnancy. The situation may be further complicated by problems such as facial fractures, C-spine injury, and head injury. Given the potential for difficulty, early ENT assessment may be warranted in some cases. Numerous issues, such as the use of cricoid pressure when intubating the parturient with a C-spine fracture may require consideration.

- During hemodynamic resuscitation it is important to remember the effects of aortocaval compression. The lateral decubitus position is preferred. This or other forms of uterine displacement must be maintained during resuscitation, transport, and perioperatively.

- Upper limb intravenous placement is preferred because of the risk of risk of venous thrombosis and infection associated with lower limb venous cannulation. ACC may also limit flow and access of injected drugs to the central circulation.

- Ephedrine continues to be vasopressor of choice in treatment of mild to moderate hypotension. However, alpha-agonists should not be avoided when necessary.

- A low threshold for placement of an arterial line is appropriate considering the difficulties in hemodynamic assessment during pregnancy and concern for the fetus. Accurate control of arterial blood gases is important.

- There should be a low threshold for the use of supplemental oxygen from the beginning of resuscitation. Remember the normal changes in blood gases when evaluating ABG results.

- Head injury is the leading cause of maternal death after trauma in pregnancy. It is most often secondary to MVA. Traumatic head injury is often associated with increases in ICP. Here, we have a conflict - therapy for increased maternal ICP may have deleterious effects on the fetus. Hyperventilation can reduce fetal oxygenation by decreasing cardiac output and producing hypocarbia (umbilical artery constriction and a left-shift in the maternal oxyhemoglobin dissociation curve). Mannitol and furosemide both cross the placenta and can lead to increased fetal plasma osmolality and decreased intravascular volume. Despite these risks, appropriate treatment of increased maternal ICP should not be unduly withheld. “The possibility of favorable maternal neurologic outcome justifies the temporary fetal risks of treatment.” Where possible, close attention should be paid to the fetal heart rate monitor during attempts to reduce maternal ICP. This will aid in appropriate titration of ICP reduction strategies Prompt surgical attention and judicious use of ventricular drains are appropriate.

- Basic radiologic investigations should not be withheld, especially when the fetus is beyond 15 weeks gestation. In fact, any diagnostic modality deemed necessary for maternal evaluation should not be withheld on the basis of its potential hazard to the fetus. Ultrasound can be used but it becomes more unreliable as gestation progresses. CT-scanning may be required. In the last 2 trimesters, diagnostic peritoneal lavage should be done via an open approach.

- Electronic fetal heart rate monitoring should be instituted as early as possible during resuscitation (when technically feasible). Fetal monitoring can help detect occult and delayed problems such as placental abruption. A suggested minimum period of monitoring is 4 hours.

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Anything else important in anesthetic management? - The principles of anesthetic management for nonobstetric surgery during pregnancy

discussed above obviously apply. - As with all trauma cases, intraoperative anesthetic management may be dominated by

resuscitation. In cases where anesthesia consists of oxygen, muscle relaxant, and minimal anesthetic, ketamine is usually the drug of choice. Remember however, that doses in the range of 2 mg/kg given during the first two trimesters can increase uterine tone and decrease uteroplacental blood flow. Use of other anesthetic agents should be guided by the patient’s condition and responses to interventions.

- Perioperative fetal monitoring is as important as discussed for nonobstetric surgery. Both fetal heart rate and tocodynamometry should be monitored before, during, and after interventions where technically feasible. The presence of an obstetrician is desirable in more severe cases of trauma where the fetus is viable.

How do you manage a maternal cardiac arrest? - Cardiac arrest during pregnancy is rare. When it occurs, we must consider the impact of

pregnancy. First and foremost, we are dealing with two patients. We must also consider the effects of pregnancy with regard to the cause of the arrest and the impact of anatomic and physiologic changes on resuscitation efforts.

- When maternal cardiac arrest occurs, standard BLS and ACLS protocols should be applied. However, CPR may be less effective in the latter part of pregnancy due to mechanical factors such as aortocaval compression and displacement of the abdominal contents towards the chest cavity.

- The carotid pulse, ETCO2, and FHR should it be monitored to assess the efficacy of CPR. - BLS guidelines may need to be modified. Relief of aortocaval compression is of paramount

importance. This must be done while still maintaining a stable surface for chest compressions. This can be done with commercial products specifically designed for this purpose or the use of such things as overturned chairs or rescuers’ thighs. Chest compression may also have to be performed higher on the sternum. There are no clear guidelines on this point. Assess efficacy frequently!

- “There are no changes to the standard ACLS algorithms for medications, intubation, and defibrillation.” However, the primary and secondary ACLS surveys have been modified for the pregnant patient. (See Table 1, I-248, Part 8 of the AHA Guidelines 2000)

- When faced with ineffective resuscitation consideration must be given to more extreme intervention. In particular, open-chest cardiac massage (without aortic cross clamp) and emergent cesarean delivery. Only the latter is discussed in the 2000 edition of the AHA ACLS guidelines (See Table 2, I-249, Part 8 of the AHA Guidelines 2000).

- Decisions regarding emergency cesarean section obviously depend upon an assessment of fetal viability. The AHA ACLS guidelines are necessary paid on this point. Dr. Georges Desjardins of the University of Miami is not so vague - “When the gestational age is less than 24 weeks, emergency caesarean delivery is usually not performed because the fetus is too small to survive and the birth is unlikely to have much effect on maternal hemodynamics. However, when gestational age is greater than 24-25 weeks, emergency cesarean birth probably will favorably affect maternal or fetal outcome.”

- When should a cesarean the delivery be performed? o Numerous factors to have to be considered including:

Cause of maternal cardiac arrest Time interval since maternal cardiac arrest Probability of maternal survival

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Probability of neonatal survival Gestational age Availability of personnel and equipment necessary to care for mother and

neonate. o Fetal survival correlates with the maternal death to delivery time and the time frame

is short. However, fetal survival after more than 20 minutes of maternal cardiac arrest has been reported.

- Optimally a “4-minute rule” has been advocated. “Perimortem cesarean delivery should begin within 4 minutes of cardiac arrest and … the fetus should be delivered within 5 minutes of maternal cardiac arrest.” This should increase the chances of both maternal and neonatal survival. The AHA guidelines state “The goal is to deliver the fetus within 4-5 minutes after the onset of arrest.” An important point to remember is that caesarean delivery is not always an abandonment of the one to save the other, but often an attempt to improve the survival of both. “… you will lose both mother and infant if you cannot restore blood flow to the mother’s heart.”

Maternal Arrest to Delivery Expected Fetal Survival < 5 minutes Excellent 5-10 minutes Good 10-15 minutes Fair 15-20 minutes Poor >20 minutes Unlikely

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Appendix 1 – Study Abstracts

Am J Obstet Gynecol 1989 Nov;161(5):1178-85 Reproductive outcome after anesthesia and operation during pregnancy: a registry study of 5405 cases. Mazze RI, Kallen B. Department of Anesthesia, Stanford University School of Medicine, CA 94305. To define the risk of adverse reproductive outcomes after nonobstetric operations during pregnancy, we linked data from three Swedish health care registries, the Medical Birth Registry, the Registry of Congenital Malformations, and the Hospital Discharge Registry, for the years 1973 to 1981. Adverse outcomes examined were the incidences of (1) congenital anomalies, (2) stillborn infants, (3) infants dead at 168 hours, and (4) infants with very low and low birth weights. There were 5405 operations in the population of 720,000 pregnant women (operation rate, 0.75%). The incidences of congenital malformations and stillbirths were not increased in the offspring of women having an operation. However, the incidences of very-low- and low-birth-weight-infants were increased; these were the result of both prematurity and intrauterine growth retardation. The incidence of infants born alive but dying within 168 hours also was increased. No specific types of anesthesia or operation were associated with increased incidences of adverse reproductive outcomes. The cause of these outcomes was not determined.

Anesthesiology 1986 Jun;64(6):790-4 Fetal risk of anesthesia and surgery during pregnancy. Duncan PG, Pope WD, Cohen MM, Greer N. In an attempt to define the risk to the fetus associated with anesthesia and surgery during pregnancy, a study was performed using health insurance data from the province of Manitoba (1971 to 1978). Each of the 2,565 women undergoing incidental surgery during pregnancy (Group A) was paired with a pregnant female not undergoing surgery (Group B) by maternal age and area of residence. Both groups were linked to a separately maintained provincial congenital-anomalies registry to ascertain the frequency of anomalies. There was no significant difference in the rate of congenital anomalies between the two groups, implying no strong teratogenic effect. However, there was an increased risk of spontaneous abortion in those undergoing surgery with general anesthesia in the first or second trimester, most notably after gynecologic procedures (estimated risk ratio = 2.00), but also following procedures anatomically remote from the conceptus (estimated risk ratio = 1.54). While it is concluded that surgery with general anesthesia is associated with a higher incidence of abortion, it is conjectural at present which factor(s) account for the observed increase in fetal risk.

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Am J Obstet Gynecol 1980 Dec 15;138(8):1165-7 Surgery during pregnancy and fetal outcome. Brodsky JB, Cohen EN, Brown BW Jr, Wu ML, Whitcher C. As many as 2% of all pregnant women undergo surgery during gestation, but there are few reports of the effects of anesthesia and surgery on fetal outcome. The present paper presents information on 287 women who had surgery during pregnancy. Surgery during early pregnancy was associated with a significant increase in the rate of spontaneous abortion compared to the rate in a control group that did not have surgery. There were no differences in the incidence of congenital abnormalities in this offspring of women who had surgery during early pregnancy. The data suggest that elective surgery be deferred during early pregnancy to minimize potential fetal loss. J Perinatol 1999 Mar;19(2):124-6 Are obstetrical personnel required for intraoperative fetal monitoring during nonobstetric surgery? Horrigan TJ, Villarreal R, Weinstein L. Department of Obstetrics and Gynecology, Medical College of Ohio, Toledo 43699-0008, USA. OBJECTIVE: To determine if the scientific literature supports the practice of electronic monitoring of the fetal heart rate (FHR) during nonobstetric surgery. STUDY DESIGN: A search of the literature from 1966 to 1995 was performed using MEDLINE. RESULTS: No fetal hypoxic mortality or morbidity has been documented from nonobstetric surgery without occurrence of a maternal hypoxic complication regardless of the use of FHR monitoring or whether alterations of the FHR occurred. CONCLUSIONS: Fetal monitoring is an indirect assessment of maternal anesthetic and surgical management that is not as specific or effective as direct assessment of the maternal parameters to detect respiratory compromise. Current clinical evidence obtained does not substantiate the need for obstetric personnel to monitor FHR changes during surgical procedures because no change in fetal outcome has been documented. J Perinatol 2000 Jun;20(4):276-7 Intraoperative fetal monitoring during nonobstetric surgery. Kendrick JM, Neiger R. Publication Types: • Comment • Letter

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Anesthesiology 2000 Aug;93(2):370-3 Arterial to end-tidal carbon dioxide pressure difference during laparoscopic surgery in pregnancy. Bhavani-Shankar K, Steinbrook RA, Brooks DC, Datta S. Departments of Anesthesia and Surgery, Harvard Medical School, Brigham and Women's Hospital, Boston, MA 02115, USA. Bhavani@capnography.com BACKGROUND: There is controversy about whether capnography is adequate to monitor pulmonary ventilation to reduce the risk of significant respiratory acidosis in pregnant patients undergoing laparoscopic surgery. In this prospective study, changes in arterial to end-tidal carbon dioxide pressure difference (PaCO2--PetCO2), induced by carbon dioxide pneumoperitoneum, were determined in pregnant patients undergoing laparoscopic cholecystectomy. METHODS: Eight pregnant women underwent general anesthesia at 17-30 weeks of gestation. Carbon dioxide pnueumoperitoneum was initiated after obtaining arterial blood for gas analysis. Pulmonary ventilation was adjusted to maintain PetCO2 around 32 mmHg during the procedure. Arterial blood gas analysis was performed during insufflation, after the termination of insufflation, after extubation, and in the postoperative period. RESULTS: The mean +/- SD for PaCO2--PetCO2 was 2.4 +/- 1.5 before carbon dioxide pneumoperitoneum, 2.6 +/- 1.2 during, and 1.9 +/- 1.4 mmHg after termination of pneumoperitoneum. PaCO2 and pH during pneumoperitoneum were 35 +/- 1.7 mmHg and 7.41 +/- 0.02, respectively. There were no significant differences in either mean PaCO2--PetCO2 or PaCO2 and pH during various phases of laparoscopy. CONCLUSIONS: Capnography is adequate to guide ventilation during laparoscopic surgery in pregnant patients. Respiratory acidosis did not occur when PetCO2 was maintained at 32 mmHg during carbon dioxide pneumoperitoneum.

World J Surg 1999 Aug;23(8):856-62 Pregnancy: A contraindication? Holthausen UH, Mettler L, Troidl H. 2nd Department of Surgery, University of Cologne, Ostmerheimerstrasse 200, 51109 Cologne, Germany. According to David L. Sackett evidence-based medicine is the conscientious, explicit, and judicious use of current best evidence when making decisions about the care of individual patients. It means integrating individual clinical expertise with the best available external evidence from systematic research. On the basis of this idea in medicine the following communication summarizes and evaluates current statements and literature on laparoscopic surgery during pregnancy. The topic is an example for

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excellent individual clinical performance on one hand, as gynecologists have perform laparoscopic procedures during pregnancy for decades. On the other hand, pregnancy is considered to be a contraindication for laparoscopic surgery by clinicians, because no excellent external evidence from systematic research is available. To find an answer to the question of whether pregnancy is a contraindication for laparoscopic surgery we performed a literature search and gained information by conducting interviews with several experts in gynecology and endoscopic operations. We concluded that there are almost no "scientific" data about endoscopic surgery during pregnancy, but gynecologists representing the "real world" seem to have no fear of the procedure for their patients. Between the two extremes, performing laparoscopic operations during pregnancy might be advantageous for maximal patient-friendly surgery, but considering pregnancy as a contraindication for the laparoscopic approach might be the safer treatment. The reader may decide that the subject on endoscopic surgery in pregnancy is still open.

Appendix 2 - “ Guidelines for Laparoscopic Surgery during Pregnancy” o Defer surgery until 2nd trimester. o Use intermittent pneumatic compression devices to prevent thrombosis in the lower

extremities. o Monitor fetal and uterine status and maternal ETCO2 and ABGs. o Use an open technique to enter the abdomen. o Avoid ACC. o Maintain low pneumoperitoneum pressures (< 15 mmHg). o Obtain preoperative obstetric consultation. Fin