Continuous minimally invasive cardiac output monitoring with the COstatus in a neonatal swine model: recalibration is necessary during vasoconstriction and vasodilation. Issue 8 (9th May 2015) - Cisternas, Alvaro F.
Summary: Background: The COstatus monitor measures cardiac output via the transpulmonary ultrasound dilution method (COTPUD ) after injection of normal saline, and can calculate continuous cardiac output (CCO) from the arterial pressure waveform. The relationship between arterial waveform and COTPUD however, might be degraded during vasoconstriction/vasodilation. Objectives: To examine if recalibration of arterial waveform‐derived CCO is required during mild vasoconstriction/vasodilation. Methods: In 10 anesthetized piglets (6.6–10.1 kg), two COstatus monitors calculated the CCO from the same femoral arterial waveform before and during infusions of phenylephrine (PE; 1 or 3 mg·kg −1 ·min −1 ) and sodium nitroprusside (SNP; 1 or 5 mg·kg −1 ·min −1 ), administered in random order. One monitor was recalibrated (CCO Recal ) after each intervention, while the other monitor was not (CCO Non‐Recal ). Recalibration was performed with COTPUD with 1 ml·kg −1 normal saline as indicator. The effects of each infusion on hemodynamic parameters were compared with baseline using paired t ‐tests. The bias, limits of agreement (LOA), and percentage error between simultaneous measurements (CCO Recal and CCO Non‐Recal ) were examined with Bland–Altman plots. Results: Infusion of PE significantly increased COTPUD, heart rate (HR), and arterial pressures but not systemic vascular resistance (SVR). Infusion of SNP decreased arterial pressures without affecting COTPUD, HR, and SVR. There was no bias between CCO Recal and CCO Non‐Recal at the baseline, but a small bias was observed during PE and SNP infusions. The LOA increased approximately 10 fold during vasoconstriction and vasodilation. The percentage error increased from ≤ 5% to 32% and 27% during PE and SNP infusions, respectively. Conclusion: Continuous cardiac output (CO) measured with the COstatus monitor requires recalibration during vasoconstriction and vasodilation, even if changes in COTPUD or SVR are not substantial. Abstract :