CARDIAC OUTPUT Monitoring ANDY CAMPBELL JOURNAL CLUB NOV 2011

Transcription

1 CARDIAC OUTPUT Monitoring ANDY CAMPBELL JOURNAL CLUB NOV 2011

2 Is keeping up the pressure enough? It is a source of regret that the measurement of flow is so much more difficult than the measurement of pressure. This has led to an undue interest in the blood pressure manometer. Most organs, however, require flow rather than pressure. Jarisch A,

3 Who are some of the Daddies of flow? George OHM s: BP = CO x SVR Hagen-Poiseuille: Adolf Eugen Fick: Frank Starling: Christian Doppler:

4 Which is best to measure flow or pressure? We talk about pressure & flow dependant organs We talk about auto-regulation of flow. We know the all important DO2 is a function of flow. DO2 = 1.34 x Hb conc. x Cardiac Output x (SaO2/100) The truth is we need both. BP = CO x SVR

5 Is there any evidence to support the use of these devices in the critical care setting? The short answer: No The closest attempt: PAC MAN Trial

6 Assessment of the clinical effectiveness of pulmonary artery catheters in management of patients in intensive care (PAC-Man): a randomised controlled trial THE CLINICAL QUESTION: Does the utilisation of the pulmonary artery catheter in critically ill ICU patients improve outcome? MAIN END POINT: Hospital Mortality. DESIGN: Prospective Single-blinded randomised controlled trial of 1041 subjects enrolled in 65 British ICUs. CONCLUSION: The authors conclude their findings indicate no clear evidence of benefit or harm in managing critically ill patients with a PAC and suggest efficacy studies that couple PAC use to explicit management protocols are necessary.

7 The Evidence:

8 Evidence Based Medicine Do the methods allow the adequate testing of the hypothesis- Yes. This is a well-designed randomised controlled trial with low risk of bias, despite reduction in sample size and early inspection of control group outcomes. Are conclusions the authors conclusions valid:- Yes They state that there is no overall evidence of benefit or harm for the PAC. What level of evidence does this study represent- 1++ What grade of recommendation can be made on this result alone- A

9 The study is not flawless. No objective inclusion criteria, 80 % of the patients in the nonpac group had some form of CO monitoring. Questions have been raised on action taken from the cardiac output data.

10 Discussion: Many clinicians feel measuring cardiac output is of benefit. As 80% of the control group had cardiac output monitoring has the ramifications for these modalities too? Can we become to fluid liberal with these monitors...a perspective on the fluids and catheters treatment trial (FACTT) (N Engl J Med 2006; 354: )

11 This topic of discussion is set to continue: Sexy Medicine VS The Old School

12 What toys are available? PAC VS Pulse contour analysis PiCCO Pulse contour analysis LiDCO Pulse contour analysis FloTrac/ Vigileo Oesophageal Doppler USCOM TTE / TOEs Gas re-breathing Transpulmonary thermodilution Thoracic bioimpedance HR / CVP / BP CRT Urine output / GCS Peripherial:Core Temperature Difference Base Deficiet, Lactate SV02

13 Pulmonary Artery Catheter PA catheter is designed to measure: intra-cardiac pressures pulmonary artery pressures Pulmonary vascular resistance cardiac output (fick or thermodilution) oxygen saturation left atrial pressure surrogate for LVEDP

14 THE ARTERIAL LINE The poor man s Swan CONTRACTILITY STROKE VOLUME DICROTIC NOTCH P [mm Hg] t [s]

15 PiCCO Pulse contour analysis with intermittent thermo-dilution measurement. via continuous pulse contour analysis Continuous pulse contour cardiac analysis (PCCO) Arterial blood pressure (AP) Heart rate (HR) Stroke volume (SV) Stroke volume variation (SVV) Systemic vascular resistance (SVR) Index of left ventricular contractility via intermittent transpulmonary thermodilution Transpulmonary cardiac output (C.O.) Intrathoracic blood volume (ITBV) Extravascular lung water (EVLW) Cardiac function index (CFI) Global end diastolic index (GEDI)

16 Mechanism:

17 LiDCO (Lithium Indicator Dilution) CO = (Lithium Dose x 60)/(Area x (1-PCV))

18 OESOPHAGEAL DOPPLER CO (cardiac output) SV (stroke volume) PV (peak velocity) HR (heart rate) FTc (corrected f low time)

19 So is this EBM? Pressure is certainly not the full story... It is similar to knowing the voltage but not the current.. The measurement of cardiac output in critical care appears to be increasingly common. Early Goal Directed Therapy is GOOD and saves lives. But currently very little information in the literature regarding the effectiveness of these monitors in these improved clinical outcomes in the CRITICAL CARE SETTING.

20 Conclusion: We need to be aware of the limitations of each of these devices when deciding to use or interpret their measurements. Single isolated values are often meaningless...think dynamically What are the clinical signs telling me? What happens when the system is challenged?

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