Factors Facilitating the Success of Fast Endotracheal Extubation after Cardiac Surgery

Objective: To study factors influencing fast endotracheal extubation after cardiac surgery. Materials and Methods: A one-year retrospective cohort study conducted via hospital medical informatics, included patients aged over 15 years old that underwent elective valvular heart surgery by means of cardiopulmonary bypass under general anesthesia. Results: Fifty-seven patients were enrolled in the present study including nine (15.8%) as fast endotracheal extubation in the operating theatre, 18 (31.6%) within eight hours postoperatively, and 30 (52.6%) non-fast endotracheal extubation eight hours after surgery. The preoperative and intraoperative factors were a younger age (p=0.018), high % left ventricular ejection function (LVEF) (p=0.023), and low creatinine level (p=0.026), as well as post cardiopulmonary bypass dexmedetomidine (p=0.01), reversal of muscle relaxant (p=0.004), and low dose dobutamine (p=0.003), respectively. However, multiple logistic regression analyses showed only two favorable factors, which were preoperative % LVEF of 60 or more (adjusted OR 11.266, 95% CI 1.700 to 74.664, p=0.012), and the intraoperative low dose dobutamine of 3 μg/kg/minute or less (adjusted OR 6.896, 95% CI 1.463 to 32.510, p=0.015). In addition, there were no significant complications. Conclusion: The factors influencing fast endotracheal extubation were preoperative% LVEF of 60 or more and intraoperative low dose dobutamine of 3 μg/kg/minute or less. Keywords: Cardiac surgery, Fast endotracheal extubation, Valvular heart disease

Successful treatment of intravenous drug abuser with refractory vasoplegic syndrome after mitral valve repair for infective endocarditis

Vasoplegic syndrome, a possible complication of cardiopulmonary bypass, is a critical state of unregulated systemic vasodilation with decreased vascular resistance and a pathological insensitivity to conventional inotropes and vasoconstrictors. This case demonstrates the use of methylene blue and hydroxocobalamin as medications in the treatment of refractory vasoplegic syndrome in the context of cardiac surgery due to their differences in mechanism of action. A 24-year-old female with history of intravenous drug abuse and hepatitis C infection underwent mitral valve repair for infective endocarditis. Preoperative transesophageal echocardiography showed normal right ventricular function, left ventricular ejection fraction of 65%–75%, and severe mitral regurgitation with vegetation. In order to maintain a mean arterial pressure over 60 mmHg during cardiopulmonary bypass, norepinephrine, epinephrine, and vasopressin infusions were required. Given the patient’s minimal response to these medications, a 1.5 mg/kg bolus of intravenous methylene blue was also given intraoperatively; vasoplegic syndrome remained refractory in the post-cardiopulmonary bypass period. A 5 g dose of intravenous hydroxocobalamin was administered in the intensive care unit postoperatively. Postoperative liver function tests were abnormal, and post-cardiopulmonary bypass transesophageal echocardiography revealed mildly decreased right ventricular function. While in the intensive care unit, the patient was placed on venoarterial extracorporeal membrane oxygenation and underwent therapeutic plasma exchange. Vasopressors were weaned over the course of the next 24 h. The patient was able to be transferred out of the intensive care unit on postoperative day 5. Traditional vasoconstrictors activate signal transduction pathways that lead to myosin phosphorylation. Vasodilatory molecules such as nitric oxide (NO) activate the enzyme soluble guanylyl cyclase (sGC), ultimately leading to the dephosphorylation of myosin. Nitric Oxide Synthase (NOS) can potentially increase NO levels 1000-fold when activated by inflammatory cytokines. Methylene blue is a direct inhibitor of NOS. It also binds and inhibits sGC. Hydroxocobalamin is a direct inhibitor of NO, likely inhibits NOS and may also act through additional mechanisms.