STATIC AND DYNAMIC INDICES OF HEMODYNAMIC MONITORING

Dr.BHARGAV.M

What is best evidence as of today?

ORWhat kind of evidence is least likely to be wrong or harm my patient ????

EVIDENCE BASED MEDICINE

Answer

Re-Question

Question If you get the same answer every time for a question- “you haven't actually progressed an inch” -unknown

“It answers all your questions and re-questions all your answers”

A BRIEF HISTORYA BRIEF HISTORY

1980’s: McMasters University in Ontario, Canada1980’s: McMasters University in Ontario, Canada

Dr. David Sackett and colleagues proposed Evidence Dr. David Sackett and colleagues proposed Evidence Based Medicine (EBM) as a new way of teaching, learning Based Medicine (EBM) as a new way of teaching, learning and practicing medicine.and practicing medicine.

Dr. Sackett defines EBM as:Dr. Sackett defines EBM as:

“…“…The conscientious, explicit, and judicious use The conscientious, explicit, and judicious use of current best evidence in making decisions of current best evidence in making decisions about the care of individual patients.”about the care of individual patients.”

The Clinical QuestionThe Clinical Question

The FIRST stepThe FIRST stepThe HARDEST stepThe HARDEST step

The The MOST IMPORTANTMOST IMPORTANT step! step!

Should I give this patient more fluids?Will this patient improve hemodynamically in response to fluids?Does my fluid bolus likely to augment cardiac output and there by tissue perfusionDoes my patient really needs fluid? How much? how long?

Good questions are the backbone of practicing EBM. It takes practice to ask the well-formulated question

More than 50 % of critically ill hypotensive patients ,fluid boluses fail to augment perfusion

Hypovolemia is not the only cause for hypotensionIf the fluid boluses doesn’t augment cardiac output, shall result in wasted resuscitation and iatrogenic harm If the patient is fluid responsive doesn’t necessarily mean fluid should be given. Whereas under-resuscitation results in inadequate organ perfusion, accumulating data suggest that over-resuscitation increases the morbidity and mortality of critically ill patients

What is PRELOAD ?

Ventricular preload is defined as the degree of cardiac muscle tension at the initiation of contraction. Clinically it is impractical to measure the “tension” in the myocardium.

Guyton AH, Hall JE. Heart muscle: the heart as a pump and function of the heart valves. In:Elsevier, S,

ed., Textbook of medical physiology. 11th edn. Elsevier, Philadelphia, 2006: 103–115.

WHAT IS VOLUME RESPONSIVENESS?“

Fluid responsive” means, response to a fluid challenge by improvement in stroke volume by at least 10%”.

Marik et al . Annals of Intensive Care 2011, 1:1

Clinical studies have, demonstrated that only approximately 50% of hemodynamically unstable critically ill patients are “volume-responsive”.

Marik PE, Cavallazzi R, Vasu T, Hirani A: Dynamic changes in arterial waveform derivedvariables and fluid responsiveness in mechanically ventilated patients. A systematic reviewof the literature. Crit Care Med 2009, 37:2642-264

STATIC INDICES CVP PAOP RVEDVI LVEDA and LVEDAI GEDV and ITBV

CVP

Large number of studies failed to discriminate b/w fluid responders and non responders

Only extreme values are of some clinical significance Degree of Hypovolemia doesn’t correlate with CVP Factors which increase intramural and transmural (pump failure,

valvular diseases, dysrhythmias, PPV, PEEP, Pneumothorax, asthma, IAP can effect the CVP

Needs invasive line

Role of CVP More than 100 studies have been published to date that have demonstrated no relationship between the CVP and fluid responsiveness in various clinical settings.

Marik PE, Baram M, Vahid B: Does the central venous pressure predict fluid responsiveness?A systematic

review of the literature and the tale of seven mares. Chest 2008, 134:172-178.Nolen-Walston RD, Norton JL, de Solis C, Underwood C, Boston R, Slack J, Dallap BL:The effects of hypohydration on central venous pressure and splenic volume in adulthorses. J Vet Intern Med 2010.

Role of CVP in “Dynamic assessment ”As noted earlier, it is best NOT to use a single value of CVP to predict volume responsiveness

Sheldon Magder et al Curr Opin Crit Care 11:264—270

PAOP

Considered gold standard for determination of LV preload Needs invasive pulmonary artery catheter Limitation: Poor correlation b/w PAOP and LVEDV No better than CVP in predicting preload responsiveness

Recent studies have clearly demonstrated that the PAOP is a poor predictor of preload and volume responsiveness.

It suffers many of the limitations of the CVP.

Osman D, Ridel C, Ray P, et al. Cardiac filling pressures are not appropriate to predict hemodynamic response to volume challenge. CritCare Med. 2007;35:64–68.

WHY DYNAMIC ASSESSMENT?

More than 50% of icu patients suffer from iatrogenic harm (fluids, interventions, polypharma, irrational antibiotics)

More evident, clinical signs and symptoms are seen after established florid organ dysfunction ( fluid overload, gut and organ edema etc) which might bring poor clinical out comes.

In the early coarse of organ dysfunction, clinical signs and symptoms are sub clinical and subtle. So need for constant and dynamic assessment to find optimal goal directed fluid therapy.

Too little fluid may result in tissue hypoperfusion and worsen organ dysfunction.

On other hand, overzealous fluid resuscitation has been associated with increased complications, increased length of intensive care unit (ICU) and hospital stay, and increased mortality

Fluid resuscitation based on down stream parameters of microcirculation (s.lactates,scvo2) may be harmful.

Normalization /decay to baseline of these parameters happen long after the actual organ recovery happen.

So continued fluid resuscitation to normalize these parameters might result in tissue edema and organ dysfunction

So dynamic assessment of indices of hemodynamics gained momentum as it questions

? Does this patient really need fluid before actual fluid is given? Does this patient fluid responsive and fall in steep portion of

ventricular contraction? How much and how long?

Concept of “fluid Responsiveness”

Only preload assessment does not mean the patient’s stroke volume will increase after a fluid challenge.

The only reason to give a patient a fluid challenge is to increase stroke volume.

If the fluid challenge does not increase stroke volume, then volume loading is of no benefit and can be even harmful.

Marik et al . Annals of Intensive Care 2011, 1:1

“DYNAMIC” MEASURES OF INTRAVASCULAR VOLUME Using heart–lung interactions to assess fluid responsiveness

is called “Dynamic” method of assessment. P.E. Marik, Handbook of Evidence-Based Critical Care, DOI 10.1007/978-1-4419-5923

Dynamic Measurements can be ..

A) in Mechanically Ventilated patientB) in Spontaneously Breathing Patient

DYNAMIC” MEASURES OF INTRAVASCULAR

VOLUME

CVP change to fluid challenge IVC/SVC Caliber changes in response to breathing Stroke Volume Variation (SVV) Pulse Pressure Variation (PPV) Dynamic Changes in Aortic Flow Velocity/Stroke Volume

Assessed by Echocardiography

AORTIC VELOCITY TIME INTEGRAL AND PEAK AORTIC VELOCITIES

Limitations of the respiratory variation in stroke volume for predicting fluid responsiveness

When a patient has some breathing efforts under mechanical ventilation –and even more when the patient is not intubated

cardiac arrhythmias conditions in which the variations in intravascular pressure

induced by mechanical ventilation are of small amplitude like low tidal volumes

high frequency ventilation. If the ratio of heart rate to respiratory rate is low, e. g., if the respiratory rate is elevated, the number of cardiac cycles per respiratory cycle may be too low to allow respiratory stroke volume variation (SVV) to occur

increased abdominal pressure open-chest conditions

Alternatives to the respiratory variation of hemodynamic signals: recent advances

The end-expiratory occlusion testThe ‘mini ’ f luid challengeThe passive leg-raising test

The passive leg-raising test

Passive Leg Raising

PLR is based on the principle that it can induce an abrupt increase in venous return secondary to auto-transfusion of peripheral blood from capacitive veins of the lower part of the body

Non invasive Doesn’t need fluids Its repeatable and reproducible Its easily reversible unlike fluid bolus Can be safely performed in patients with poor cardiac reserve Can reliably assess volume responsiveness even if pt has

spontaneous breathing effort or arrhythmias

In response to PLR…

• Descending aortic blood flow is measured by esophageal

Doppler• LVEDV, stroke Volume etc are measured by transthoracic

echocardiography • PPV and SVV can be measured by PiCOO or FloTrac Vigileo etc

Marik et al. Annals of Intensive Care 2011, 1:1

LIMITATIONS..

Intra-abdominal hypertension (intra-abdominal pressure > 16 mmHg) impairs venous return and reduces the ability of PLR to detect fluid responsiveness

Echocardiographic techniques are operator dependent. It can not be used as continuous real-time monitoring.

Marik et al. Annals of Intensive Care 2011, 1:1

A meta-analysis, which pooled the results of eight recent studies, confirmed excellent value of PLR to predict fluid responsiveness in critically ill patients

Intensive Care Med 2010, 36:1475-1483

FLUID RESPONSIVENESS IN “SPONTANEOUSLY BREATHING PATIENT

” During spontaneous breathing, due to variable (and sometimes inadequate) Tidal Volumes, variable results are produced, which will be difficult to assess.

Assessment of fluid responsiveness in patients under spontaneous breathing activityRev Bras Ter Intensiva. 2009; 21(2):212-218

SV min

TAKE HOME MESSAGE

More than 50% of icu patients suffer from iatrogenic harm (fluids, interventions, polypharma, irrational antibiotics)

Too little fluid may result in tissue hypoperfusion and worsen organ dysfunction. On other hand, overzealous fluid resuscitation has been associated with increased complications, increased length of intensive care unit (ICU) and hospital stay, and increased mortality

Even normal healthy person is fluid responsive, doesn't mean fluids should be given. fluids should be given only if there is hypotension or signs of tissue hypoperfusion and patient is fluid responsive

dynamic assessment of indices of hemodynamics should be done more often as it questions

? Does this patient really need fluid before actual fluid is given? Does this patient fluid responsive and fall in steep portion of

ventricular contraction? How much and how long? More research is need to validate and see outcomes

“Every question has an answer ,if there is question without answer, the problem is not in the question, but in the search itself”

THANK YOU