Dr masjedi hemodynamic monitoring in ICU
•Download as PPT, PDF•
10 likes•833 views
The document discusses various techniques for hemodynamic monitoring, including both conventional and advanced methods. It provides an overview of the history of hemodynamic monitoring and outlines some of the goals of different monitoring devices. The document then reviews several specific monitoring techniques, such as arterial lines, central venous catheters, pulmonary artery catheters, echocardiography, pulse contour analysis, and electrical bioimpedance. Both advantages and disadvantages of each method are discussed.
More Related Content
What's hot
What's hot (20)
Similar to Dr masjedi hemodynamic monitoring in ICU
Similar to Dr masjedi hemodynamic monitoring in ICU (20)
More from mansoor masjedi
More from mansoor masjedi (20)
Recently uploaded
Recently uploaded (20)
Dr masjedi hemodynamic monitoring in ICU
- 1. Conventional & Advanced Hemodynamic Monitoring Mansoor Masjedi MD , FCCM Head of Trauma ICUs , Shaheed Rajaee Hospital, SUMS Updates on hemodynamic monitoring and shock in ICU Teh., Iran ; 28th Dec. 2017
- 2. I have no conflicts of interest
- 4. Outline • Introductions • What we have previously – A line / CVC/ PAC • Advanced techniques for haemodynamic monitoring
- 5. • 1960s: golden age of vasopressors • 1970s: golden age of inotropes • 1980s: • 1990s till now: History of Monitoring Pressure, arterial line & CVP Cardiac output, PA catheter SvO2 , relative balance between oxygen supply and demand Better understanding of tissue oxygenation, Right & left ventricular function , Functional monitoring,PiCCO, continuous CO Less invasive, TEE
- 6. Hemodynamic monitoring trutH •No monitoring device, no matter how simple or complex, invasive or non-invasive, inaccurate or precise will improve outcome •Unless coupled to a treatment , which itself improves outcome Pinsky & Payen. Functional Hemodynamic Monitoring, Springer, 2004
- 7. Goals of Monitors To assure the adequacy of perfusion Early detection of inadequacy of perfusion To titrate therapy to specific hemodynamic end point To differentiate among various organ system dysfunctions Hemodynamic monitoring for individual patient should be physiologically based and goal oriented
- 8. Different Environments Demand Different Rules Emergency Department Trauma ICU Operation Room ICU & RR Rapid, invasive, high specificity Somewhere in between ER and OR Accurate, invasive, high specificity Close titration, zero tolerance for complications Rapid, minimally invasive, high sensitivity
- 9. Hemodynamic monitors (1) • Traditional invasive monitors • Arterial line • CVP & ScvO2 • PA catheter, CCO, SvO2 • Functional pressure variation • Pulse pressure variation • Stroke volume variation • Alternative to right-side heart catheterization • PiCCO • Echocardiography • Transesophageal echocardiography (TEE) • Esophageal doppler monitor • Electrical bioimpedence
- 10. Old equipments • Arterial line – Real time SBP, DBP, MAP – Pulse pressure variation (∆PP) • ΔPP (%) = 100 × (PPmax - PPmin)/([PPmax + PPmin]/2) • >= 13% (in septic pts,) discriminate between fluid responder and non respondaer (sensitivity 94%, specificity 96%) Am J Respir Crit Care Med 2000, 162:134-138
- 11. Arterial line • Advantages – Easy setup – Real time BP monitoring – Beat to beat waveform display – Allow regular sampling of blood for lab tests • Disadvantages – Invasive – Risk of haematoma, distal ischemia, pseudoaneurysm formation and infection
- 12. Old equipments • Central venous catheter – Measurement of CVP, medications infusion and modified form allow for dialysis
- 13. Limitation of CVP Systemic venoconstriction Decrease right ventricular compliance Obstruction of the great veins Tricuspid regurgitation Mechanical ventilation
- 14. Central venous catheter • Advantages – Easy setup – Good for medications infusion • Disadvantages – Cannot reflect actual RAP in most situations – Multiple complications • Infections, thrombosis, complications on insertion, vascular erosion and electrical shock
- 15. Old equipment • Pulmonary arterial catheter
- 16. Indications for PAP monitoring • Shock of all types • Assessment of cardiovascular function and response to therapy • Assessment of pulmonary status • Assessment of fluid requirement • Perioperative monitoring
- 17. PAC • Advantages – Provide lot of important haemodynamic parameters – Sampling site for SvO2 • Disadvantages – Costly – Invasive – Multiple complications (eg arrhythmia, catheter looping, balloon rupture, PA injury, pulmonary infarction etc) – Mortality not reduced and can be even higher Crit Care Med 2003;31: 2734-2741 JAMA 1996;276 889-897
- 19. Advance in haemodynamic assessment • Modification of old equipment • Echocardiogram and esophageal doppler • Pulse contour analysis and transpulmonary thermodilution • Partial carbon dioxide rebreathing with application of Fick principle • Electrical bioimpedance
- 20. Objective To compare measurements of cardiac output using a new pulmonary artery catheter with those obtained using two " gold standard " methods: the periaortic transit time ultrasonic flow probe and the conventional pulmonary artery thermodilution.Design Prospective clinical trial.Setting Cardiac surgery operating room and surgical ICU in a university hospital.Material and methods In the operating room, a new pulmonary artery catheter (truCCOMS system) was inserted in eight patients. A periaortic flow probe was inserted in four of them. Measurements of cardiac output obtained with the truCCOMS catheter and with the flow probe were compared at different phases of the surgical procedure. In the intensive care unit, the cardiac output displayed by the truCCOMS monitor was compared with the value obtained after bolus injection performed subsequently.Results In the operating room (70 measurements), the coefficient of correlation between cardiac output measured by the flow probe and the truCCOMS system was r2 = 0.79, the bias was +0.11 l/min with a precision of 0.47 l/min, and limits of agreement –0.83 to +1.05 l/min. In the intensive care unit (108 measurements), the coefficient of correlation between cardiac output measured by thermodilution and the truCCOMS system was r2 = 0.56, the bias was –0.07 l/min, the precision was 0.66 l/min, and the limits of agreement were –1.39 to +1.25 l/min.Conclusion The truCCOMS system is a reliable method of continuous cardiac output measurement in cardiac surgery patients.
- 21. TruCCOMS system • Advantage – Continuous CO monitoring – Provision of important haemodynamic parameter as PAC • Disadvantage – Invasive – Costly – Complications associated with PAC use
- 24. Transthoracic echo • Assessment of – cardiac structure – ejection fraction – cardiac output • Based on 2D and doppler flow technique
- 25. Static (much like central venous pressure [CVP]/pulmonary artery occlusion pressure [PAOP] ) Eyeballing Left ventricular end-diastolic area (LVEDA) Mitral early to late filling velocities (E/A) Early mitral filling velocity to early diastolic mitral annular velocity (E/E’) CO Dynamic Aortic blood flow Respiratory variation Vena cava collapsibility Passive leg raising STATIC VERSUS DYNAMIC PARAMETERS
- 26. LVEDA Left parasternal short-axis view, mid-papillary level Normal LVEDA is 9.5–22 cm2 ; very low (<5.5 cm2 /m2 body surface area) suggests hypovolemia Beware suboptimal image quality (especially border definition and midpapillary positioning ( Mostly useful as a reality check for eyeballing
- 27. EYEBALLING Echocardiography has been validated for left ventricular (LV) volume measurements. Such measurements are often adequate to guide fluid volume therapy, but only at extremes of cardiac filling and function.
- 28. ECHOCARDIOGRAPHY: SURROGATES FOR PAOP Mitral E/A Mitral E/E’ Pulmonary venous inflow But PAOP doesn’t predict fluid response!
- 29. DYNAMIC PARAMETERS Passive mechanical ventilation Aortic blood flow variation Vena cava collapsibility (distensibility( Spontaneous breathing Passive leg raising
- 30. PASSIVE MECHANICAL VENTILATION Exaggerates hemodynamic effects noted with passive, PPventilation in hypovolemic subjects Right ventricular (RV) preload effects LV stroke volume effects Passive = paralyzed or heavily sedated, not initiating breaths Requires at least 8 mL/kg tidal volume, by convention Requires sinus rhythm
- 31. ECHOCARDIOGRAPHY FOR STROKE VOLUME VARIABILITY Various techniques exploit the net effects of positive- pressure ventilation on stroke volume/LV filling in hypovolemic patients Echocardiography provides a useful, informative alternative to Swan-Ganz, indicator-dilution, thoracic bio-impedance/reactance, etc.
- 32. Pulsed Wave Doppler VTI = Area Under Curve AORTIC VELOCITY TIME INTERVAL (VTI( RESPIRATORY VARIATION
- 33. PEAK VELOCITY: SURROGATE FOR VTI 2001 study by Feissel et al studied 19 patients Feissel M, Michard F, Mangin I, et al. Respiratory changes in aortic blood velocity as an indicator of fluid responsiveness in ventilated patients with septic shock. Chest. 2001;119:867-873.
- 34. AORTIC BLOOD VELOCITY RESPIRATORY VARIATION Pulsed- Wave Doppler Peak Aortic Velocity
- 35. AORTIC BLOOD VELOCITY RESPIRATORY VARIATION (Vpeakmax - Vpeakmin) ∆Vpeak (%) = ----------------------------------- x 100 (Vpeakmax + Vpeakmin) / 2 Vpeakmax Vpeakmin
- 36. VELOCITY CAN BE A SURROGATE FOR VTI Chest. 2001;119:867-873.
- 37. AORTIC BLOOD VELOCITY RESPIRATORY VARIATION ∆Vpeak = (0.63 - 0.46)/[(0.63 + 0.46)/2] x 100 ∆Vpeak = 31.2% Fluid Responsive
- 38. AORTIC BLOOD VELOCITY RESPIRATORY VARIATION ∆Vpeak = (1.12 - 0.88)/[(1.12 + 0.88)/2] x 100 ∆Vpeak = 24% Fluid Responsive
- 39. AORTIC BLOOD VELOCITY RESPIRATORY VARIATION ∆Vpeak = (0.78 - 0.71)/[(0.78 + 0.71)/2] x 100 ∆Vpeak = 9.3% Fluid Unresponsive
- 40. AORTIC VELOCITY VARIABILITY PITFALLS Beware RV failure: Cor pulmonale Severe ARDS Severe pul. hypertension Resp. distress with huge pressure swings, e.g., status asthmaticus Usual aortic velocity variability (AoV) pegged to typical intrathoracic pressure shifts Cardiac translation can exaggerate AoV variability High positive end-expiratory pressure
- 41. VENA CAVA COLLAPSIBILITY: A SURROGATE FOR RV PRELOAD Superior Vena Cava Only accessible via transesophageal echocardiography (TEE( Intrathoracic Beware superior vena cava (SVC) syndrome Inferior Vena Cava Generally accessible via transthoracic echocardiography (TTE) Extrathoracic Beware abdominal compartment syndrome
- 42. VENA CAVA COLLAPSIBILITY TEE Right PA Ascending Aorta SVC Inferior Vena Cava Right Atrium TTE - Subcostal View
- 43. na cava collapsibility = (Dmax - Dmin)/Dmax x 10 SVC Collapsibility Patients who had an SVC collapsibility index o >36% were volume responsive. Patients with an SVC collapsibility index of <36% were not volume responsive.
- 44. SVC COLLAPSIBILITY a Cava Collapsibility = (2.1 - 1.1)/2.1 Vena Cava Collapsibility = (Dmax - Dmin)/Dmax x 100 Vena Cava Collapsibility = 47.6% Fluid Responsive M-mode
- 45. SVC COLLAPSIBILITY a Cava Collapsibility = (2.2 - 1.7)/2.2 Vena Cava Collapsibility = 22% Fluid Unresponsive
- 46. IVC DISTENSIBILITY INDEX Feissel M, et al. Intensive Care Med. 2004;30:1834- 1837. Barbier C, et al. Intensive Care Med. 2004;30:1740- 1746. • Patients intubated • No respiratory efforts • VT >8 mL/kg PBW
- 49. IVC PITFALLS Beware of movement in and out of plane, which will exaggerate IVC collapsibility. Many authors recommend short-axis view of IVC to confirm. Beware the hepatic vein confluence. Do not mistakenly interrogate aorta.
- 50. 2012 SEPSIS GUIDELINES 20-40 mL/kg CVP to 8-12 mm Hg Norepinephrine for a MAP <65 mm Hg Dobutamine for ScVO2 <70% or organ hypoperfusion Lactate or oliguria Limited Echocardiography Guide Parasternal Apical 4-chamber Subcostal Biventricular function Pericardial evaluation IVC diameter 1. Dellinger RP, Levy MM, Rhodes A, et al. Surviving Sepsis Campaign: international guidelines for management of severe sepsis and septic shock: 2012. Crit Care Med. 2013;41:580- 637. 2. Kanji HD, McCallum J, Sirounis D, et al. Limited echocardiography-guided therapy in subacute shock is associated with change in management and improved outcomes. J Crit Care. 2014:29:700-705.
- 51. ACTIVE VENTILATION Active spontaneous, negative-pressure ventilation Includes many pts on the ventilator )though poorly studied( Highly variable stress on cardiac filling/function Thwarts most efforts at stroke volume variability Postural change: bring the blood to the heart
- 52. PASSIVE LEG RAISE (PLR( Wait 90 seconds to 3 minutes between measurements Observe privacy Use straight arms
- 53. PASSIVE LEG RAISING 12% Lamia B, et al. Intensive Care Med. 2007;33:1125-1132. Maizel J, et al. Intensive Care Med. 2007;33:1133-1138. PLR-induced changes in VTIAo
- 54. Determining Probability Rarely is a single measure definitive Integrate multiple inputs to make a prediction, e.g., AoV variability + IVC + CVP + clinical instinct Then assess results: echocardiography provides a useful and rapid method English statistician, philosopher and Presbyterian minister
- 55. SUMMARY Static measures rarely predict fluid responsiveness. Dynamic measures often predict fluid responsiveness. Passively ventilated LV stroke volume effects: aortic VTI/Vpeak variability RV preload: IVC/SVC variability Actively ventilated Passive leg raise Synthesize multiple inputs to make assessment
- 57. QUESTION This image is from a 51-year-old man with septic shock. Is this patient fluid responsive? A.Yes B.No C.Uncertain LVEDA 18 cm2 GET MORE DATA
- 58. QUESTION This image is from a 40-year-old woman with septic shock. Is this patient fluid responsive? A.Yes B.No C.Uncertain
- 59. QUESTION This image is from a 40-year-old woman with septic shock. Is this patient fluid responsive? A.Yes B.No C.Uncertain LVEDA 5 cm2
- 60. QUESTION This is an image of a 75-year-old man with a urinary tract infection and shock. Is this patient fluid responsive? A.Yes B.No C.Uncertain
- 61. QUESTION This is an image of a 75-year-old man with a urinary tract infection and shock. Is this patient fluid responsive? A.Yes B.No C.Uncertain ∆Vpeak = (0.63 - 0.46)/[(0.63 + 0.46)/2] x 100 ∆Vpeak = 31.2%
- 62. Transthoracic echo • Advantages – Fast to perform – Non invasive – Can assess valvular structure and myocardial function – No added equipment needed • Disadvantages – Difficult to get good view (esp whose on ventilator / obese) – Cannot provide continuous monitoring
- 63. Transesophageal echo • CO assessment by Simpson or doppler flow technique as mentioned before • Better view and more accurate than TTE • Time consuming and require a high level of operator skills and knowledge
- 64. Esophageal aortic doppler US • Doppler assessment of descending aortic flow • CO determinate by measuring aortic blood flow and aortic CSA • Correlate well with CO measured by thermodilution Crit Care Med 1998 Dec;26(12):2066-72 Decending aorta
- 65. Esophageal aortic doppler US • Advantages – Easy placement, minimal training needed (~ 12 cases) – provide continuous,real-time monitoring – Low complications – Minimal infective risk • Disadvantages – High cost – Poor tolerance at awake pt, so for those intubated – Probedisplacement can occur during prolonged monitoring and patient’s turning – High interobserver variability when measuring changes in SV in response to fluid challenges
- 67. What is the PiCCO-Technology? 2 - Pulse Contour Analysis CV Bolus injectio n PULSIOCAT H CALIBRATIO N 1 - Transpulmonary Thermodilution injection t T P t A unique combination of 2 techniques for advanced hemodynamic and volumetric management
- 68. LiDCO system
- 69. SVSVmaxmax SVSVminmin SVSVmeanmean SVSVmaxmax – SV– SVminmin SVV =SVV = SVSVmeanmean Stroke Volume Variation: Calculation Stroke Volume Variation (SVV) represents the variation of stroke volume (SV) over the ventilatory cycle. SVV is... ... measured over last 30s window … only applicable in controlled mechanically ventilated patients with regular heart rhythm
- 70. Pulse Pressure Variation: Calculation PPPPmaxmax – PP– PPminmin PPV =PPV = PPPPmeanmean PPPPmaxmax PPPPmeanmean PPPPminmin Pulse pressure variation (PPV) represents the variation of the pulse pressure over the ventilatory cycle. PPV is... …measured over last 30s window …only applicable in controlled mechanically ventilated patients with regular beat rhythm
- 71. Decision tree for hemodynamic / volumetric monitoring CI (l/min/m2 ) GEDI (ml/m2 ) or ITBI (ml/m2 ) ELWI* (ml/kg) (slowly responding) >3.0<3.0 >700 >850 <700 <850 >700 >850 <700 <850 ELWI* (ml/kg) GEDI (ml/m2 ) or ITBI (ml/m2 ) CFI (1/min) or GEF (%) <10 >10 <10 <10 <10>10 >10 >10 V+ V+! V+!V+Cat Cat OK! V- >700 >850 700-800 850-1000 >4.5 >25 >5.5 >30 >4.5 >25 700-800 850-1000 Cat >5.5 >30 >700 >850 700-800 850-1000 700-800 850-1000 ≤10 ≤10 ≤10 ≤10 V- V+ = volume loading (! = cautiously) V- = volume contraction Cat = catecholamine / cardiovascular agents ** SVV only applicable in ventilated patients without cardiac arrhythmia >700 >850 <10Optimise to SVV** (%)<10 <10 <10 R E S U L T S T A R G E T T H E R A P Y 1. 2. <10 <10 <10 <10
- 72. Pulse contour analysis • Advantages – Almost continuous data of CO / SV / SV variation – Provide information of preload and EVLW • Disadvantages – Minimal invasive – Optimal arterial pulse signal required • Arrhythmia • Damping • Use of IABP
- 73. Partial carbon dioxide rebreathing with application of Fick principle • Fick principle is used for CO measurement • CO = VO2 / (CaO2 – CvO2) = VCO2 / (CvCO2 – CaCO2) • Based on the assumption that blood flow through the pulmonary circulation kept constant and absence of shunt • Proportional to change of CO2 elimination divided by change of ETCO2 resulting from a brief rebreathing period • The change was measured by NICO sensor
- 74. Partial carbon dioxide rebreathing with application of Fick principle • Advantages – Non invasive • Disadvantages – Only for those mechanically ventilated pt – Variation of ventilation modality and presence of significantly diseased lung affect the CO reading – Not continuous monitoring
- 75. • Electrodes are placed in specific areas on the neck & thorax • A low-grade electrical current, from 2 - 4 mA is emitted & received by the adjacent electrodes • Impedance to the current flow produces a waveform • Through electronic evaluation of these waveforms, the timing of aortic opening and closing can be used to calculate the left ventricular ejection time and stroke volume
- 76. Electrical bioimpedance • Advantage – Non invasive • Disadvantage – Reliability in critically ill pts still not very clear
- 77. Haemodynamic monitoring enable early detection of change in pt’s conditions New techniques provide reasonably good results & less invasive Always correlate the readings / findings with clinical pictures in order to provide the best treatment options
Editor's Notes
- Many factors in the literature attempt to determine whether patients will respond to volume expansion. These factors are grouped as static and dynamic parameters. Static factors don’t change over time: for example, central venous (CVP) or pulmonary artery occlusion pressure (PAOP) and end-diastolic area. These dynamic parameters change with time over different ventricular loading conditions.
- In a parasternal short axis view, an area can be calculated from a tracing. The problem with that is the normal end-diastolic area is wide, somewhere between 10 and 20 cm2. It&apos;s not useful to determine where a patient falls on the Frank-Starling curve. A low end-diastolic area (less than 5 cm2) suggests hypovolemia. Eyeballing or tracing the border isn&apos;t helpful most of the time, because most people fall into the normal range.
- First echo is sepsis with hyperdynamic hypovolemia and low LVEDA (~8cm2), while second echo is normal. Third echo is sepsis but LVH and normal LVEDA (~12cm2). The LV volumes look smaller because the RV is dilated.
- The literature touts certain surrogates for wedge pressure. These can be calculated with Doppler through the mitral valve or the pulmonary vein. But the wedge pressure doesn&apos;t indicate whether the patient is going to respond to fluid, so these procedures aren&apos;t that useful.
- In patients who are receiving passive mechanical ventilation—meaning heavily sedated and the ventilator is doing all the work—check the aortic blood flow variation and whether or not the vena cava is collapsible. In those who are spontaneously breathing, these measures are not as accurate, so raise the legs to see if cardiac output increases.
- Huang et al, Crit Care Med. 2008, used PiCCOplus monitor to establish that high positive end-expiratory pressure (PEEP) and low tidal volume in ARDS patients also causes wide RV preload effects.
- Echocardiology reveals stroke volume variation in a noninvasive manner.
- To look at respiratory variation of the aortic velocity time interval, obtain an apical five-chamber view. Use pulsed wave Doppler instead of continuous wave, and place the cursor at the left ventricle outflow tract. Each resulting waveform is essentially the stroke volume going through the outflow tract or the aortic annulus. Next, trace the biggest and smallest curves to determine the area under the curve for each. These areas provide the difference between the maximum and the minimum velocity time intervals (VTI), which are analogous to the largest and smallest stroke volume and how volume changes with respiration.
- A study by Feissel, et al (Chest. 2001;119:867-73) looked at 19 sedated patients in septic shock. The larger the variation of VTI, the more dramatic the increase in cardiac output following a fluid bolus.
- It is a little cumbersome to have to trace the VTI and so, as a surrogate of the VTI, use the maximum velocity of each of those curves. Again, use the five-chamber view. With the pulsed wave Doppler, use the peak velocity. Peak velocity varies with respiration, providing variation of the maximum and minimum, not just one value.
- Add the maximum and minimum peak velocity to this equation. Basically, it&apos;s the difference between the maximum and minimum divided by the average of the two, then multiplied by 100 to get a percentage.
- The bigger the difference between minimum and maximum peak velocity, the more dramatic the increase in cardiac output with volume expansion. In this study, the authors split their patients between who responded to fluid and who didn&apos;t. The magic number seemed to be 12% or 12.5%. If the variation is more than 12.5% in sinus rhythm at 8 mL/kg, the patient is more likely to respond to fluid. If it is less than 12.5%, do not give fluid. The end-diastolic area didn&apos;t seem to separate responders from non-responders. It&apos;s just not that helpful.
- Let’s run through some examples. We see maximum of 0.63 in this patient and an minimum of 0.46. If you put that into the equation, the variation is 31%. So, that&apos;s somebody that you are going to give fluid to.
- Here’s another patient. Without even doing the math, you can appreciate the sinusoidal wave; how big the difference is between the maximum peak velocity and the minimum peak velocity. Doing the math, again, this patient has a variation of 24% and would respond to fluid.
- Lastly, these waves are very consistent, with changes that are not very dramatic. If you do the math on this patient, that&apos;s somebody that doesn&apos;t respond to fluid. So, it&apos;s a fairly straight-forward concept.
- There are some things to be cautious about when you are using this. This does not work as well in patients with RV failure, whether it&apos;s from ARDS or standing pulmonary hypertension; it&apos;s not as predictive of who will benefit. High PEEP also can cause problems and, again, you need sinus rhythm for that. If you are in an arrhythmia, every stroke volume is different. So, you can&apos;t really say that this is going to work for somebody in atrial fibrillation, for example.
- Another dynamic parameter is vena cava collapsibility. You can use either the superior vena cava if you&apos;re able to do transesophageal echocardiography, or you can use the inferior vena cava.
- This is the TTE scan of the ascending aorta, the right pulmonary artery, the main pulmonary artery, and the SVC. In a subcostal view with the transducer pointed cephalad and caudad, the IVC is visualized emptying in the right atrium next to the liver.
- This is the equation for vena cava collapsibility. It&apos;s the difference between the maximum diameter of the IVC or SVC minus the smallest diameter, and it ultimately is divided by the maximum diameter. This is not divided by the average, like the aortic variation. Notice that this has nothing do with how big the IVC or SVC is; the maximum diameter of the IVC could be massive, but variation would indicate fluid responsiveness. The absolute number is unimportant; collapsibility is the meaningful factor. Putting the SVC variation into this equation, patients in this study who had greater than 36% collapsibility were likely to respond to fluid expansion. Patients with less than 36% collapsibility were unlikely to respond.
- The best way to look at collapsibility is to use M-mode because the maximum diameter or minimum diameter of the IVC or SVC will not be missed. M-mode captures about 200 pictures per second, whereas two-dimensional echocardiography scans at maybe 30 pictures per second. Here&apos;s an example of M-mode scanning through the SVC and plotting 200 times per second. We can measure the minimum and maximum diameter of the IVC, then put it into the appropriate equation. Here the variation is over 36% so this patient would respond to fluid.
- Conversely, here&apos;s an SVC without much variation. The equation result is less than 36%, so no fluid for this patient.
- Looking now at the IVC, the more variation there is in the IVC collapsibility, the more dramatic the increase in cardiac output or stroke volume with volume expansion. Feissel, et al used the formula: Divc max - Divc min / mean x 100%. They called this the “IVC variation” and set a threshold of &gt;12%. The maximum diameter of the IVC did not predict fluid responsiveness. So, don&apos;t look at the IVC size; what is important is collapsibility.
- Here are some more examples. This is an M-mode scan. Applying the equation isn’t necessary. This is completely collapsed. This patient will respond to fluid.
- Here, don&apos;t focus on how wide the IVC is; just focus on the fact that that&apos;s not collapsing at all. So no fluid is needed.
- There are a couple of matters to keep in mind. Sometimes that IVC will move in and out of the ultrasound plane, so maintain a good picture throughout the whole respiratory cycle. If the mid-portion of the IVC is visualized half the time and only the corner of it the remainder of the time, collapsibility will be exaggerated. The hepatic vein empties into the IVC near where it all empties into the right atrium. If M-mode is performed there, the IVC diameter will appear falsely large. Remember that the aorta is very close to the IVC.
- Historical control, and not an RCT.
- Until now, the discussion has focused on patients on passive ventilation, who are not generating a lot of intrathoracic negative pressure. Patients who are breathing on their own are going to get off the ventilator sooner. So might these individuals respond to an autotransfusion?
- Slow transition to emphasize the patience required. Pitfalls: - Abdominal compartment syndrome - Open abdomen - Unstable pelvic/low lumbar fracture
- These results illustrate how this maneuver works. The responders to the leg raise had an increase in VTI, whereas the non-responders didn&apos;t. Both groups returned to baseline with the legs lowered. Following volume administration, passive leg raise responders also responded to volume. So, this leg maneuver predicts the patients that are going to respond.
- No single parameter is the perfect measure. You may wish to combine IVC and aortic variation, CVP and urine output. Look at a couple of findings to improve an educated guess.
- What are the take-home messages? Try to use the dynamic parameters to predict patient responsiveness. If the patient is receiving passive ventilation, it&apos;s helpful to use IVC collapsibility or stroke volume variation based on aortic VTI. If the patient is actively breathing, autotransfusion via passive leg raise can predict who will respond to volume. Use all available input to make a decision.
- The parasternal long-axis view is foreshortened, so one must exercise caution in interpreting it (first answer is C).
- But the parasternal short axis, with confirmed low LVEDA, suggests fluid responsiveness (second answer is A).
- C. Aortic velocity variability is unreliable in the presence of RV failure. The systolic excursion velocity (RV S’) could be used. In this case it’s likely to be slow, making aortic velocity variation (AoVV) unreliable. 2 clips, 1 question.
- C. Aortic velocity variability is unreliable in the presence of RV failure. The systolic excursion velocity (RV S’) could be used. In this case it’s likely to be slow, making aortic velocity variation (AoVV) unreliable. 2 clips, 1 question.