Noninvasive Cardiac Output Monitoring Combined With Critical Care Ultrasound for Postoperative Volume Management in Cardiac Surgery Patients: A Randomized Controlled Trial.

INTRODUCTION: Postoperative hemodynamic instability and low cardiac output syndrome are common complications following cardiac surgery. Conventional volume management guided by central venous pressure and mean arterial pressure has well-documented limitations. Noninvasive cardiac output monitoring (NICOM) and critical care ultrasound (CCUS) provide complementary, real-time hemodynamic and volumetric assessments. This randomized controlled trial evaluated whether NICOM+CCUS-guided fluid management improves clinical outcomes in cardiac surgery patients with postoperative hemodynamic instability.

MATERIALS AND METHODS: In this single-center, parallel-group randomized controlled trial conducted at Tongji University East Hospital (January-December 2024), 86 adults (≥18 y) with postoperative hemodynamic instability cardiac index (CI) < 2.5 L/min/m2 plus ≥1 of: lactate >2 mmol/L or norepinephrine >0.05 μg/kg/min after cardiac surgery were randomized 1:1 (control n = 43, observation n = 43) to conventional monitoring (central venous pressure/mean arterial pressure-guided) or NICOM+CCUS-guided management. Eighty-one patients (control n = 40, observation n = 41) completed analysis.

PRIMARY OUTCOMES: extubation time category (<24 h, 24-48 h, >48 h), left ventricular ejection fraction (LVEF), and brain natriuretic peptide at intensive care unit (ICU) discharge.

SECONDARY OUTCOMES: lactate normalization time (<2 mmol/L), 24-h urine output, net fluid balance, acute heart failure incidence, intra-aortic balloon pump use, mechanical ventilation duration, and ICU length of stay. Categorical variables were analyzed using χ2/Fisher's exact tests; continuous variables were analyzed using t-test/Mann-Whitney U-test after Shapiro-Wilk normality testing. Within-group changes were assessed using paired t-test/Wilcoxon test.

SIGNIFICANCE: P < 0.05 (two-sided).

RESULTS: Baseline characteristics were balanced (P > 0.05). The observation group had higher 24-h extubation rates 92.7% versus 60.0%; odds ratio 7.96 (95% CI 2.14-29.63), P < 0.001 and greater LVEF improvement median Δ6.7% (95% CI 3.2-10.2), P < 0.001 versus control at discharge. The greater LVEF improvement in the observation group was accompanied by lower net fluid balance, earlier lactate normalization, and reduced diuretic use, suggesting that optimized volume status and improved oxygen delivery contributed to enhanced myocardial recovery. Brain natriuretic peptide reduction was more pronounced Δ-104.0 ± 68.2 versus -58.8 ± 62.1 pg/mL; P = 0.031. Secondary outcomes favored the observation group: lactate normalization 16.2 ± 8.5 versus 28.3 ± 11.4 h; mean difference (MD) -12.1 h (95% CI -16.7 to -7.5), P < 0.001, urine output 4846.7 ± 1653.4 versus 4086.5 ± 1113.8 mL; MD 760.2 mL (95% CI 148.6-1371.8), P = 0.015, net fluid balance 101.4 ± 32.3 versus 347.6 ± 64.2 mL; MD -246.2 mL (95% CI -278.5 to -214.0), P < 0.001, acute heart failure 4.8% versus 17.5%; odds ratio 0.24 (95% CI 0.05-1.17), P = 0.045, mechanical ventilation 15.1 ± 9.3 versus 27.3 ± 11.5 h; MD -12.2 h (95% CI -16.9 to -7.5), P < 0.001, and ICU stay 31.1 ± 13.3 versus 42.5 ± 13.1 h; MD -11.4 h (95% CI -17.4 to -5.4), P < 0.001.

CONCLUSIONS: NICOM+CCUS-guided fluid management significantly improved hemodynamic stability, cardiac recovery, and resource utilization compared to conventional monitoring. This noninvasive strategy reduced fluid overload and complications in high-risk cardiac surgery patients. Multicenter trials enrolling a broader range of cardiac surgical procedures with long-term follow-up are warranted.