WHAT IS OBESITY

• It is second only to smoking as a preventable cause of death.

• Defination - obesity can be defined as a disease because it a physiological dysfunction of the human organism with genetic, environmental, and endocrinological cause.

WHEN DOES OBESITY DEVELOPE

• When the calorie intake exceeds the energy expenditure over a long period of time.

• Factors influencing- genetic, behavioral, cultural, socioeconomic and metabolic.

• Ex- leptin deficiency, Prader Willi syndrome etc.

HOW TO MEASURE OBESITY

• BMI= Wt(kgs)/ Ht 2 (m)• Waist circumference.

BMIclassification BMI( Kg/m2) risk

UNDERWEIGHT < 18.5 INCREASED

NORMAL WEIGHT 18.9- 24.9 LEAST

OVERWEIGHT 25- 29.9 INCREASED

OBESE

CLASS 1 30- 34.9 HIGH

CLASS 2 35- 39.9 VERY HIGH

CLASS 3 40-49.9 EXTREMELY HIGH

SUPEROBESE > 50 EXTREMELY HIGH

WAIST CIRCUMFERENCEWAIST CIRCUMFERENCE

NORMAL WT OVERWT OBESE CLASS 1

< 102 CM< 88 CM

LEAST RISK INCREASED HIGH

>120CM> 88 CM

INCREASED HIGH VERY HIGH

INCIDENCE OF HEALTH RISK METABOLIC SYNDROME MIDDLE AGED(>30%)

TYPE 2 DIABETES BMI> 23

HTN BMI> 25, 5X OBESITY

CAD AND STROKE 3.6X OBESITY, 70% LVH, 10% CCF,

RESPIRATORY EFFECTS NECK CIRCUMFERENCE >43(m), > 40.5(F)- OSA, DAYTIME SOMNOLENCE, PUL HTN

CANCER ENDOMETRICAL Ca, 10% CANCER DEATHS

REPRODUCTIVE FUNCTION 6% INFERTILY(F), IMPOTENCY (M)

OSTEOARTHRITIS ELDERLY

LIVER AND GALL BLADDER DISEASE NAFLD & NASH, 20% DYSLIPEDEMIA

METABOLIC SYNDROME FEATURES

ABDOMINAL OBESITY

ATHEROGENIC DYSLIPIDEMIA (TG, HDL, APO B)

ELEVATED BLOOD PRESSURE

INSULIN RESISTENCE WITH OR WITHOUT GLUCOSE INTOLERENCE

PROINFLAMATORY STATES

OTHERS ( endocrinological dysf, microalbuminuria, pcod, hypoandrogenism, hyperurecemia)

Comman in men, > 60, south asians, drugs- corticosteroids, SSRI, antidepressants

CRITERIACRITERIA VALUES

ABDOMINAL OBESITY W.C> 102(M) & > 88(F)

TRIGLYCERIDES > 150 MG/DL

HDLP <40(M) AND <50MG/DL( F)

BLOOD PRESSURE > 130/90 mmHg

FASTING GLUCOSE >110 mg/dl

• Inflammatory response plays an important role in metabolic syndrome.

• Visceral adipose tissue is a major source of proinflammatory cytokines- TNF-a, IL-6, adiponectin.

• raised levels of proinflammatory cytokines contribute to insulin resistance.

• Adipokines- leptin is reduced which results in increased appetite , slow metabolism and susceptibility to proinflammatory stimuli. They also contribute to progession of heart disease and DM in obese patients.

EFFECTS ON RESPIRATORY SYSTEM• Fat accumulation on the thorax and abdomen decreases chest wall and lung

compliance.• Increase in blood volume as more volume is required to perfuse the additional

body fat. Polycythemia of chronic hypoxemia contributes to increased total blood volume.

• Increased elastic resistance and decreased compliance of the chest wall further reduces total respiratory compliance while supine, leading to shallow and rapid breathing, increased work of breathing,

• Respiratory muscle efficiency is below normal in obese individuals.• Decreased pulmonary compliance leads to decreased functional residual capacity

(FRC), vital capacity, and total lung capacity. Residual volume and closing capacity are unchanged.

• Reduced FRC Leads to small airway closure, ventilation-perfusion mismatch, right-to-left shunting, and arterial hypoxemia.

• Anesthesia worsens this situation such that up to a 50% reduction in FRC occurs in the obese anesthetized patient compared with 20% in the nonobese individual

• ERV is the most sensitive indicator of the effect of obesity on pulmonary function.

OSA/ OSH SYNDROME• Characterized by recurrent episodes of upper

respiratory obstruction occurring during sleep.• OSA- complete cessation of airflow during

breathing lasting 10sec or longer despite of maintenance of neuromuscular ventilatory efforts and occurring 5times or > during sleep, decrease of Sao2 of atleast 4%.

• OSH- partial reduction of airflow of > 50% lasting for 10sec, occurring 15 times or more/ hour of sleep and associated with decrease Sao2 of atleast 4%.

DIAGNOSIS

• Polysomnography.• Sleep study- EEG, ECG, EOG, Capnography, nasal/oral

airflow, esophagial pressure,BP, pulse oximetry & room noise are monitered and recorded.

RESULTSMILD DISEASE - AHI 5-15 EVENTS/ HOUR

MODERATE DISEASE- AHI 15-30 EVENTS/ HOUR

SEVERE DISEASE- AHI . 30 EVNTS/ HOUR

RISK ASSOCIATED WITH MODERATE AND SEVERE DISEASE- systemic and pulmonary HTN, LVH, cardiac arrhythmias, cognitive impairment, presence of daytime somnolence.

Anesthetic considerations

• Adipose tissue in oral and pharnygeal tissues.• Increased fat deposition in the lateral walls

decreases the size of the airway and changes the shape of the oropharynx – ellipitical, short transverse and long AP diameter.

• Makes mask ventilation and laryngoscopy difficult • Contributes to increased severity of airway

obstruction during GA• airway obstruction after Extubation increases with

the use of opiates and sedative drugs .

• It is necessary to diagnose and treat OSA before surgery.

• T/T- CPAP, conservatively- weight reduction , avoidance of alcohol intake before bedtime ,and sleeping on one side.

MANAGEMENT OF OBESITY

• NON – SURGICAL• SURGICAL

NON- SURGICAL

1. Daily exercise for 30min2. Statins- to reduce LDL3. Statins and ezetimide ( inhibits interstinal

absorption of cholesterol)4. Fibrates- decrease triglycerides and increase HDL-C5. Omega-3 fatty acids- decrease TG & insulin

resistance6. Salt restriction- HTN+ Obesity+ metabolic

syndrome

Behavioral modifications.

Drugs- BMI> 30

APPETITE SUPRESSANTS• PHENTERMINE- adrenergic

reuptake inhibitor, decreases appetite and food intake , increases RMR. S/E- taccy, HTN

• SIBUTRAMINE- adrenergic and serotninergic agent which supresses appetite & increases thermogenesis. S.E- htn, taccy, dry mouth, insomnia

LIPASE INHIBITOR• ORLISTAT- binds to lipase

and prevents both absorption and digestion of dietary fats. S/E- prevents absorption of fat sol vitamins, diarrhea, steatorrhea, flautulence, incontinence, oily recal discharge.

SURGICAL MANAGEMENT

• BARIATRIC SURGERIES- surgical alterations of the small intestine or stomach with a view towards producing weight loss

• RESTRICTIVE- decreases the capacity of food intake by creating a small pouch in proximal part of stomach. Vertical band gastroplasty and laparoscopic gastric band

• MALABSORPTIVE – gastric bypass and pancreatic diversion.

contraindications

• Unstable CAD• Uncontrolled severe OSA• Psychiatric disorder• Mental retardation(IQ<60)• Drug abuse and malignancy

ANESTHETIC MANAGEMENT

• PRE-OP EVALUATION• INTRA-OP- patient positioning - airway management - drugs/ induction - extubation/ transport• POST-OP MANAGEMENT

PREOPERATIVE EVALUATION-

o Assessment of HTN, DM, heart failure, OSA o Examination of history of previous surgery,

their anesthetic challenges, need for ICU admission, surgical outcome and weight of the pt at that time.

Lab investigations

• FBS, lipid profile, CBC, ferritin, vit B12, thyrotroin and 1,25-dihydroxyvitamin D

• Screening for OSA• LFT- NAFLD, NASH,( portal HTN & Cirrhosis is

considered as C.I)

Intraoperative care

• Patient positioning- rhabdomyolysis from pressure on the gluteal muscles RF & Death

• Cushioning gel pads, wt bearing rolls• Pressure points should be adequately padded• Axillary roll – pts with excessive axillary tissue• Minimize compression injury or development

of compartment syndrome.

Airway management

• Difficulty in ventilation and laryngoscopy short thick neck, large tongue, redundant pharyngeal soft tissue.

• Assessing –MP, TMD, Neck circumference, MO, neck mobility, USG-pretracheal soft tissue.

• Placing the patient in semirecumbent position (30D) elevation with the head in sniffing position, ramped positioning & head elevation.

• Minimized- awake intubation, topicalized direct laryngoscopy with modest sedation, sedated fiberoptic, ( LMA, Fiberoptic shd be available in case of emergency)

TROOP ELEVATION PILLOW/HELP

INFLATABLE PILLOW(HELP)

• Low VC, inspiratory capacity, ERV, FRC, CC may fall in supine or recumbent position rapid desaturation.

• Application of CPAP (8-10cms H2O)during preoxygenation & PEEP & mechanical ventilation after induction is advised.

• To avoid desaturation & atelecatsis/ increase airway pressure- 30 D reverse trendelenburg position.

Maneuvers to maintain lung vol and ventilation

• Increasing TV- 13-22ml/kg• PEEP- 10 cm • Lap surg- sustained lung inflation to 50cms

H2O & PEEP 12cms increase Pao2• Extubation- adequate muscle strength,

sustained tetanus NS, 5sec head lift, awake following commands can be extubated. CPAP/Pressure support can be applied.

Drugs

• Sedatives, opioids, benzodiazepine decrease the pharyngeal musculature tone

• Volatile agents- diminish the ventilatory response to CO2 .

• there is increased volume of distribution of lipophilic drugs( benzodizepines, barbiturates)

• Dosing of the commonly used drugs like propofol, vec, rocuronium,remifentanyl- IBW & thipopental, midaz, scholine,atra, cisarta, fentanyl, sufentanyl- TBW

• Thiopental. Prolonged somnolence with thiopental is expected because it is highly lipophilic and has a larger VD in the obese patient.

• Propofol. There is no difference in initial VD between obese and nonobese patients with propofol.Propofol has high affinity for excess fat and other well-perfused organs.

• Benzodiazepines. Benzodiazepines persist long after discontinuation because they are highly lipophilic drugs with a larger VD in obese patients. Midazolam, although considered short acting, has the potential for prolonged sedation in obese patients because larger initial doses are required to achieve adequate serum concentrations.

• Neuromuscular Blocking and Reversal Agents. Pseudocholinesterase activity increases linearly with increasing weight and larger extracellular fluid compartment; therefore, the dose of succinylcholine should be increased somewhat. Nondepolarizing muscle relaxants should be administered according to LBW to prevent delayed recovery because of increased VD and impaired hepatic clearance. Prompt early reversal but slow full recovery has been documented in overweight and obese patients during neostigmine-induced reversal of vecuronium.

• The choice of volatile agents is based on tissue solubility, blood gas partition coeff, fat- blood pat coeff

• Desflurane is the agent of choice or sevoflurane.

• Nitrous oxide is avoided as these patients have more o2 demand, in lap surgery can increase bowel gas volume & make the procedure more challenging.

Induction• Obese patients have a risk of aspiration due to

delayed gastric emptying.• Prophylaxis for acid aspiration is required.• Regional anesthesia is a safe option in such

patients but it is technically more difficult- larger needles or USG guidance.

• Care should be taken regarding the dose as there can be cephalad spread of the drug and block( smaller epidural space).

• Monitoring- no invasive monitoring is required unless the patient is suffering from any comorbid condition.

• In conditions like obesity-hypoventilation syndrome with PHT- PA catheter or TEE.

• For ease of peripheral access – USG guidance or CVC can be used.

• For NIBP-adequate sized cuff shd be available/ arterial catheter can be placed.

• Intra-op ABG analysis- guidance for I/O ventilation and extubation.

Other considerations

• Appropriate sized table availability.• Strapping the patient during sedation and sleep• Placing a bean bag under the patient to keep

the patient from sliding.• Armboards should have extra padding.• Thermal management- warmers.• Fluids- greater requirement, 4-5L of crystalloids

may be needed to prevent ATN.

EXTUBATION & TRANSPORT• The patient should be preferably extubated in the semirecumbent

position, which has less adverse effect on respiration.• Supplemental oxygen should be administrated after extubation. • Lifting devices such as the HoverMatt (Patient Handling

Technologies, Allentown, PA), the Patient Transfer Device (PTD; Alimed, Dedham, MA), and gantry-style mechanical lifting devices that use a sling are useful for transporting morbidly obese patients onto or off the operating table.

• The PTD can be combined with the Walter Henderson Maneuver to safely and gently transfer obese patients onto their postoperative beds.

Post-op pain management

• IV- analgesia via PCA• Thoracic epidural• Local anesthetic infilteration in the wound

with adjuctive non- narcotic medication.

Post operative management

• Bariatric patients should stay at the same location after surgery.

• They are maintained on CPAP/ biphasic positive airway pressure machines as much as possible with monitoring of SpO2.

• Patients with difficult intubation should have a labeled armband , a note by the attending anesthesiologist explaining the difficulty in intubation and equipements to tackle difficult airway should be kept ready.

Post-op complications

• Bariatric surgeries are considered to be safe• Mortality is associated with intestinal leakage,

Intra abdominal bleeding, suture line dehiscence, small bowel obstruction & deep wound infection.

• Categorized- wound, GIT, pulmonary and CVS• Complications are considerably lesser in

laparoscopic than open surgeries.• Pul embolism and DVT

ALL SURGERIES GASTRIC BANDING ROUX-EN-Y

EARLY •Bleeding•Infection•Dehydration•Peritonitis•Bowel obstruction•Perforation•Pneumonia•DVT/PE•Death

•Band slippage•Band malfunction•infection

Leak from site

LATE CholelithiasisCholecystitisGERD/dysphagiaFat soluble & vit B12 deficiency

Anorexia ,band slippageBand malfunctioninfection

Small bowel obstructionMarginal ulcersPancreatitisStrictures.

REFERENCES

• MILLER’S ANESTHESIA• BARASH

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