Continuous minimally invasive cardiac output monitoring with the COstatus in a neonatal swine model: recalibration is necessary during vasoconstriction and vasodilation.

Background The COstatus monitor measures cardiac output via the transpulmonary ultrasound dilution method ( CO_TPUD) after injection of normal saline, and can calculate continuous cardiac output ( CCO) from the arterial pressure waveform. The relationship between arterial waveform and CO_TPUD 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 CO_TPUD 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 CO_TPUD, heart rate ( HR), and arterial pressures but not systemic vascular resistance ( SVR). Infusion of SNP decreased arterial pressures without affecting CO_TPUD, 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 CO_TPUD or SVR are not substantial. [ABSTRACT FROM AUTHOR]