Pulmonary Artery Catheter (PAC) Accuracy and Efficacy Compared with Flow Probe and Transcutaneous Doppler (USCOM): An Ovine Cardiac Output Validation

Abstract

Background. The pulmonary artery catheter (PAC) is an accepted clinical method of measuring cardiac output (CO) despite no prior validation. The ultrasonic cardiac output monitor (USCOM) is a noninvasive alternative to PAC using Doppler ultrasound (CW). We compared PAC and USCOM CO measurements against a gold standard, the aortic flow probe (FP), in sheep at varying outputs. Methods. Ten conscious sheep, with implanted FPs, had measurements of CO by FP, USCOM, and PAC, at rest and during intervention with inotropes and vasopressors. Results. CO measurements by FP, PAC, and USCOM were 4.0 ± 1.2 L/min, 4.8 ± 1.5 L/min, and 4.0 ± 1.4 L/min, respectively, (n = 280, range 1.9 L/min to 11.7 L/min). Percentage bias and precision between FP and PAC, and FP and USCOM was −17 and 47%, and 1 and 36%, respectively. PAC under-measured Dobutamine-induced CO changes by 20% (relative 66%) compared with FP, while USCOM measures varied from FP by 3% (relative 10%). PAC reliably detected −30% but not +40% CO changes, as measured by receiver operating characteristic area under the curve (AUC), while USCOM reliably detected ±5% changes in CO (AUC > 0.70). Conclusions. PAC demonstrated poor accuracy and sensitivity as a measure of CO. USCOM provided equivalent measurements to FP across a sixfold range of outputs, reliably detecting ±5% changes.

Obituary: pulmonary artery catheter 1970 to 2013

“…An increase in SV of 10 to 15% is used to define fluid responsiveness [66]. This threshold is significantly below the ability of the PAC to detect a change in CO [22]. In addition to its inability to determine fluid responsiveness the CO itself has very little utility in guiding patient management.…”

Pressure recording analytical method and bioreactance for stroke volume index monitoring during pediatric cardiac surgery

“…Percentage error was 91.7%. Baseline SVI appeared to be similar, but PRAM SVI was systematically greater than bioreactance thereafter, with the highest gap after the fluid loading phase: 13 (12)(13)(14)(15)(16)(17)(18) mlÁm À2 vs. 23 (19)(20)(21)(22)(23)(24)(25) mlÁm À2 , respectively, P = 0.0013. A multivariable regression model showed that a significant independent inverse correlation with patients' body weight predicted the CI difference between the two methods after fluid challenge (b coefficient À0.12, P = 0.013).…”

“…None of these methods is currently validated and/or recommended during pediatric cardiac surgery. Furthermore, as evidenced by a recent research where thermodilution CO was compared with surgically implanted ultrasonic flow probes in an ovine model , the PAC showed to be unreliable for detection of CO changes <30–40%. Critchely et al .…”

“…Methods: A single-center prospective observational cohort study in children undergoing cardiac surgery with cardiopulmonary bypass (CPB) was conducted. Twenty children below 20 kg with median (interquartile range) weight of 5.3 kg (4.1-7.8) and age of 6 months (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) were enrolled. Data were collected after anesthesia induction, at the end of CPB, before fluid administration and after fluid administration.…”

New Methods of Monitoring Shock in Children

“…However, this methodology has itself been challenged and USCOM precision is comparable to other non-invasive CO measurement techniques [17]. The precision of PAC itself is increasingly being questioned [31]. USCOM has been compared to echocardiography Doppler measures, 'estimated' (USCOM) and 'measured' left ventricular outflow tract diameters were not significantly different, but USCOM consistently 'overestimated' CO, particularly in children with septic shock [29].…”