PURPOSE: Minimally invasive mitral valve surgery (MIMVS) is associated with similar morbidity and mortality compared to standard sternotomy-based mitral valve surgery. With MIMVS, there is a trend toward shorter hospital stay, less pain, and faster recovery to preoperative function. Some of these patients subsequently developed acute respiratory failure (ARF) requiring intubation and mechanical ventilation for > 48 hours after surgery. The study purpose is to evaluate the percentage of patient developing ARF and to identify the factors associated with this complication.
METHODS: A total of 483 patients underwent MIMVS at our institution between January 2001 and September 2009. We first reviewed all charts to evaluate the percentage of patients who developed ARF as defined above. This was followed by a detailed retrospective chart review of 15 patients randomly selected from each group (ARF vs. no ARF) to evaluate the factors resulting in this complications. The factors included age, BMI, cross clamp time, fluid balance, set tidal volume (VT) per ideal body weight (IBW), mean pulmonary artery pressures (mPAP), perfusion time and cardiac index (CI).
RESULTS: 20 of the 483 patients (4%) developed ARF. Compared to controls, the patients who developed ARF following MIMVS had higher BMI 24.9 vs. 29.2 (P< .007), were older 55.1 vs. 64.3 years (P< .05), and had more positive fluid balance during the first 24 hours -6.8 cc vs. 1934 cc (P< .01). During the immediate post-operative period, patients with ARF had higher mPAP 25.1 vs. 19.3 (P< .02), lower CI 2.3 vs. 2.7 (P< .03) and a higher VT per IBW 12.2 vs. 10.5 (P< .003). All other parameters did not reach statistical significance. 4 of the 15 patients developed ARF due to cardiogenic pulmonary edema.
CONCLUSION: Obesity, older age, higher mPAP, lower CI, higher VT ventilation and positive fluid balance during the peri-operative period may be risk factors for prolonged respiratory failure in patients undergoing robotic MIMVS.
CLINICAL IMPLICATIONS: A clinical prediction model based on the above results may help identify patients at high risk for ARF after MIMVS.
DISCLOSURE: Khawaja Rahman, No Financial Disclosure Information; No Product/Research Disclosure Information