Volume status and volume responsiveness in postoperative cardiac surgical patients: An observational, multicentre cohort study

Abstract

Background The best strategy to identify patients in whom fluid loading increases cardiac output (CO) following cardiac surgery remains debated. This study examined the utility of a calculated mean systemic filling pressure analogue (Pmsa) and derived variables to explain the response to a fluid bolus. Methods The Pmsa was calculated using retrospective, observational cohort data in the early postoperative period between admission to the intensive care unit and extubation within 6 hours. The venous return pressure gradient (VRdP) was calculated as Pmsa − central venous pressure. Concurrent changes induced by a fluid bolus in the ratio of the VRdP over Pmsa, the volume efficiency (Evol), were studied to assess fluid responsiveness. Changes between Pmsa and derived variables and CO were analysed by Wilcoxon rank‐sum test, hierarchial clustering and multiple linear regression. Results Data were analysed for 235 patients who received 489 fluid boluses. The Pmsa increased with consecutive fluid boluses (median difference [range] 1.3 [0.5‐2.4] mm Hg, P = .03) with a corresponding increase in VRdP (median difference 0.4 [0.2‐0.6] mm Hg, P = .04). Hierarchical cluster analysis only identified Evol and the change in CO within one cluster. The multiple linear regression between Pmsa and its derived variables and the change in CO (overall r2 = .48, P < .001) demonstrated the best partial regression between the continuous change in CO and the concurrent Evol (r = .55, P < .001). Conclusion The mean systemic filling Pmsa enabled a comprehensive interpretation of fluid responsiveness with volume efficiency useful to explain the change in CO as a continuous phenomenon.

Letter by Veen et al Regarding Article, “Incidence and Clinical Significance of Worsening Tricuspid Regurgitation Following Surgical or Transcatheter Aortic Valve Replacement: Analysis From the PARTNER IIA Trial”

“…Contrary to aortic valve regurgitation, tricuspid valve regurgitation is highly dependent on volume status and difficult to quantify. 2 Temporary change in volumetric status after cardiac surgery is common, 3,4 which may be accompanied by temporary increase in tricuspid valve regurgitation. Therefore, some patients with an increase in tricuspid valve regurgitation in the first 30 days may show a decrease in tricuspid valve regurgitation in the next 30 days, whereas other may show a persistent increase in tricuspid valve regurgitation.…”

Protracted fibrinolysis resistance following cardiac surgery with cardiopulmonary bypass: A prospective observational study of clinical associations and patient outcomes

“…The ICU length of stay (ICU LOS; defined as the time in hours between ICU admission to the time of the medical decision to discharge from ICU 19 ) was used to reflect the trajectory of ICU-level postoperative support following confirmation of a composite correlation with surgical and post-operative mortality risks, organ dysfunction and duration of respiratory support 20 (Figure S1). In addition to the continuous ICU LOS variable, a dichotomized ICU LOS above the 75th percentile (97.5 h, based on 470 admissions to Liverpool ICU included in previous observational studies [21][22][23] ) was used to describe patients with an extended stay. Sensitivity analyses using different cut-offs for ICU LOS were performed (see Table S1).…”