close attention objectives: Individual comparison of cardiac output via intermittent thermodilution and Fick technique athwart a wide range of cardiac outputs Design: Prospective clinical investigation.

close attention objectives: Individual comparison of cardiac output via intermittent thermodilution and Fick technique athwart a wide range of cardiac outputs

Design: Prospective clinical investigation.

Setting: Multidisciplinary ICUs of couple teaching hospitals in Vancouver, British Columbia.

Participants: Eighteen critically ill patients who had pulmonary and systemic arterial catheters and in whom active support was being withdrawn.

Interventions: Measurement of thermodilution cardiac output and calculation of Fick cardiac output while support was withdrawn. Active support was withdrawn in a three-step process: removal of vasopressors followed by means of decrease in fraction of inspired oxygen to 021 and finally removal of mechanical ventilation.

Measurements and results: Simultaneous Fick and thermodilution cardiac output were obtained above a wide range. Fick calculated cardiac output were obtained using the Fick equation with oxygen uptake (V[Osub2]) being measured with indirect calorimetry. V[Osub2] determinations were made using five measurements across 5 min, with the mean being used for following analysis. Thermodilution cardiac outputs were determined through the mean of five measurements, with the first being discarded. Coefficient of variation was calculated for the V[Osub2] and thermodilution cardiac output undivided hundred thirty-six simultaneous cardiac output were obtained in 18 patients with a mean APACHE (acute physiology and chronic health evaluation) II score of 255 The range of cardiac output was 139 to 1695 L/min. Linear regression analysis set up a good correlation of the data fixs with an R of 085 Bias and precision calculations raise a bias of - 017 L/win with the upper and lower limits of agreement being 296 L/win and - 330 L/min, respectively. In patients with high cardiac output (> 7 L/min), the bias was - 190 with the limits of agreement being 187 L/min and - 567 L/min. The coefficient of variation for V[Osub2] was 46% and for thermodilution cardiac output was 775%

Conclusions: There was proper consistency of each of the measurements with a subdued coefficient of variation. The bias for the whole assemblage was small, but the limits of agreement enlargeed into a clinically relevant area, resulting in a lack of agreement. In patients with high cardiac output the Fick protected to consistently produce higher cardiac output compared to thermodilution, suggesting a systematic error.

solution words: bias; cardiac output; critically ill; Fick; indirect calorimetry; precision; regression analysis; thermodilution

Abbreviations: APACHE = acute physiology and chronic health evaluation; MSOF = multisystem organ failure; V[Osub2] = oxygen consumption

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Management of hemodynamic status is a crucial part of care in the critically ill. To assist the clinician, a variety of [i]modus operandi[/i]s are available to assess cardiac function. (1-4) Pulmonary artery catheters have helped us understand hemodynamic dysfunction in many clinical situations. Although many hemodynamic variables may be generated with a pulmonary artery catheter, assessment of the cardiac output is united of the most important. (56) Intermittent thermodilution, being common of the most established orderly dispositions of cardiac output determination, utilizes a computerized calculation of melt based on changes in temperature following an injection of a appoint amount of fluid via a pulmonary artery catheter. (78)

lately pulmonary artery catheter utilization has tend hitherward under increasing scrutiny. Concerns regarding the risk/benefit ratio of this invasive monitoring technique have been raised on a number of authors, (9-11) and scientific trials are being supplicationed for its ongoing use. Hence, alternative techniques for the measurement of cardiac output throughout a wide range of cardiac output and clinical conditions may be of potential use in the critically ill.

The refinement of classifications of indirect calorimetry, through the analysis of respiratory gases, has allowed the measurement of oxygen uptake (V[Osub2]) at the bedside in the critically ill. according to applying the Fick principle, cardiac output can be obtained as V[Osub2] divided from the arteriovenous oxygen content difference. (1213)

These sum of two units methods of obtaining cardiac output have been validated independently. (14-16) Published comparisons of Fick and thermodilution have been done in make subordinates not critically ill, (17-23) have solitary correlation and not agreement, (172021) used improper agreement analysis, (24-26) or limited patient clusters with a small range of cardiac output (2227) The studies are also limited by way of having a small range of cardiac output in succession any given patient even although the entire set may be broad. The objective in this cogitation was to assess the agreement, precision, and bias of these sum of two units different methods of cardiac output determination in a critically ill population from one side of to the other a wide range of cardiac output forward individual patients.

MATERIALS AND METHODS

Patients

Simultaneous determinations of cardiac output were obtained in 18 critically ill patients admitted to the ICUs of Vancouver General Hospital and St Paul's Hospital, Vancouver, British Columbia. A part of this data station has been previously reported. (28) Patients were prospectively studied if they met the following inclusion criteria: mechanical ventilation support, systemic and pulmonary artery catheters in place, and agreement of the attending physician and families to discontinue life support. Patients were classified into septic and nonseptic clusters Sepsis was defined by air of positive culture findings and the demeanor of tachypnea (minute ventilation > 10 L/min), tachycardia (pulse > 90 beats/min), and hyperthermia or hypothermia (core temperature > 383[degrees]C or < 356[degrees]C) along with a manifestation of altered organ perfusion. Altered organ perfusion was defined as a Pa[O.sub.2]/fraction of inspired oxygen < 280 urine output < 05 mL/kg for at least 1 h or an increased serum lactate even Sepsis was supported in all patients according to autopsy evidence of a source of infection.

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