Static and dynamic indices of hemodynamic monitoring
- 1. STATIC AND DYNAMIC INDICES OF HEMODYNAMIC MONITORING Dr.BHARGAV.M What is best evidence as of today? OR What kind of evidence is least likely to be wrong or harm my patient ????
- 2. 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”
- 3. A BRIEF HISTORYA BRIEF HISTORY 1980’s: McMasters University in Ontario, Canada1980’s: McMasters University in Ontario, Canada Dr. David Sackett and colleagues proposed EvidenceDr. David Sackett and colleagues proposed Evidence Based Medicine (EBM) as a new way of teaching, learningBased 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 useThe conscientious, explicit, and judicious use of current best evidence in making decisionsof current best evidence in making decisions about the care of individual patients.”about the care of individual patients.”
- 4. The Clinical QuestionThe Clinical Question The FIRST stepThe FIRST step The HARDEST stepThe HARDEST step TheThe MOST IMPORTANTMOST IMPORTANT step!step!
- 5. 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 perfusion Does 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
- 6. More than 50 % of critically ill hypotensive patients ,fluid boluses fail to augment perfusion Hypovolemia is not the only cause for hypotension If 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
- 7. 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.
- 8. 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
- 9. 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
- 12. STATIC INDICES CVP PAOP RVEDVI LVEDA and LVEDAI GEDV and ITBV
- 13. 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
- 14. 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.
- 15. 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
- 16. 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
- 17. 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.
- 18. 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
- 19. 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?
- 20. 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
- 21. “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
- 22. Dynamic Measurements can be .. A) in Mechanically Ventilated patient B) in Spontaneously Breathing Patient
- 25. 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
- 31. AORTIC VELOCITY TIME INTEGRAL AND PEAK AORTIC VELOCITIES
- 32. 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
- 33. Alternatives to the respiratory variation of hemodynamic signals: recent advances The end-expiratory occlusion test The ‘mini’ fluid challenge The passive leg-raising test
- 34. The passive leg-raising test
- 35. 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
- 36. 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
- 37. 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
- 38. 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
- 39. 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
- 42. SV min
- 48. 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
- 49. “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