Date of Award

January 2015

Document Type

Thesis

Degree Name

Medical Doctor (MD)

Department

Medicine

First Advisor

John Geibel

Subject Area(s)

Surgery

Abstract

Vasoplegic syndrome is a state of vasodilatory shock characterized by decreased systemic vascular resistance (SVR) with preserved cardiac index (CI). This syndrome has been largely studied at cardiopulmonary bypass (CPB) cessation and in the immediate postoperative period. The literature lacks a uniform definition of vasoplegia and a large retrospective study with precise hemodynamic data, complicating the understanding of this potentially deadly syndrome. The goal of this study was to create the largest retrospective database to date in the literature (n = 1,776) with precise hemodynamic information at set intervals throughout the operative and 24-hour postoperative periods in order to solidify a dichotomous and a stratified definition of vasoplegia. The dichotomous definition used in this study is mean arterial pressure (MAP) < 60 mm Hg, CI > 2.4 L/min/m2, and SVR < 800 dyn*sec*cm-5 with at least one concurrent vasopressor. The stratified definition investigates worsening MAP and SVR in parallel with increasing vasopressor requirement. With these definitions, the aims were to characterize the precise timing of and morbidities associated with vasoplegia. The prevalence of vasoplegia in this study is 18.5%. Of the vasoplegic patients, 91.1% experience vasoplegia intraoperatively, with a peak prevalence at the cessation of CPB and a steep decline postoperatively. A substantial subset of patients begins to experience vasoplegia earlier than previously described, both at CPB start and throughout the use of CPB. For all time points combined, 67.8% experience no worse than mild vasoplegia, 27.3% experience no worse than moderate vasoplegia, and 4.91% experience severe vasoplegia. Vasoplegia is strongly statistically correlated with multiple poor outcomes by multivariate logistic regression including death (odds ratio [OR] 2.17), thirty-day readmission (OR 1.61), and prolonged ventilation (OR 2.59). The OR for prolonged ventilation increases with worsening severity of vasoplegia, whereas readmission is significant only for mild vasoplegia, perhaps explained by the increased incidence of death without readmission that occurs for sicker patients. The ORs for death worsen by stratification when removing critical mediators such as prolonged ventilation and perioperative renal failure. By linear regression, prolonged ICU stay is significant only for the subgroups of moderate and severe vasoplegia, with coefficients of 1.17 and 6.30, respectively.

Comments

This thesis is restricted to Yale network users only. This thesis is permanently embargoed from public release.

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