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PulseCO monitoring system by Dr. Charles E. Smith, MD, FRCPC, provides accurate estimates of preload and cardiac function through pulse contour analysis. Utilizing SPV, SV, and calibration using EF, this system assists in diagnosing hypovolemia and guiding treatment decisions. Learn about calibration methods, pitfalls, and the system's applications in various clinical scenarios.
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PulseCO Monitoring System Charles E. Smith, MD, FRCPC Professor of Anesthesia MetroHealth Medical Center Case Western Reserve University Cleveland, Ohio
Estimates of Preload • Clinical: BP, HR, capillary refill, urine • Postural changes • CVP • PAC • Echo
Systolic Pressure Variation • Difference between maximal + minimal values of systolic BP during PPV • down: ~ 5 mm Hg due to venous return • SPV > 15 mm Hg, or down > 15 mm Hg: • highly predictive of hypovolemia Marik: Anaesth Intensive Care 1993;21:405. Coriat: Anesth Analg 1994;78:46
Pulse Contour Analysis • 1. Transform BP waveform into volume – time waveform • 2. Derive uncalibrated SV • SV x HR = CO • 3. Calibrate using Li indicator [LidCO], Swan Ganz, or known SV from ejection fraction (Echo) • Assumptions: • PPV induces cyclical changes in SV • Changes in SV results in cyclical fluctuation of BP or SPV Linton R: 1997, 1998, 2000
PulseCO SPV + SV • Predicts SV in response to volume after cardiac surgery + in ICU[Reuter: BJA 2002; 88:124; Michard: Chest 2002; 121:2000] • Similar estimates of preload v. echo during hemorrhage[Preisman: BJA 2002; 88: 716] • Helpful in dx of hypovolemia after blast injury [Weiss: J Clin Anesth 1999; 11:132]
Calibration Using EF • Obtain uncalibrated SV tracing from PulseCO monitor • Estimate EF from preop echo or baseline cardiac status [usual SV approx 0.7-1 ml/kg] • Enter calibration factor on monitor
Calibration Using EF Example 1: uncalibrated SV reading 140 ml/beat; 70 kg pt with normal EF; calibration factor = 0.5 Example 2: uncalibrated SV reading 100 ml/beat; 70 kg pt with DCM; calibration factor = 0.3
Pitfalls with SPV + SV • Inaccurate if • AI • IABP • Problems if • pronounced peripheral arterial vasoconstriction • damped art line • Arrhythmias