Pharmacokinetics of Cefazolin in Patients With Obesity Undergoing Surgery Requiring Cardiopulmonary Bypass.

OBJECTIVE: The authors' objective was to determine the adequacy of an institutional standard dosing practice for infection prophylaxis in open cardiac surgery in patients heavier than 120 kg undergoing cardiopulmonary bypass. DESIGN: A prospective, single-center, open-label study was used to determine if cefazolin serum concentrations were maintained above the minimum inhibitory concentration (MIC) throughout surgery. A pharmacokinetic model describing cefazolin disposition was developed for perioperative patients with morbid obesity, based on these values. Probability of target attainment was evaluated across the clinically relevant MIC spectrum. SETTING: Maine Medical Center is an academic hospital in Portland, Maine, affiliated with Tufts University School of Medicine. PARTICIPANTS: Twenty patients scheduled for cardiac surgery requiring cardiopulmonary bypass who weighed at least 120 kg. INTERVENTIONS: All patients received 2 g of cefazolin intravenously (IV) within 1 hour before incision, an additional 1 g injected into the cardiopulmonary bypass circuit at the initiation of bypass, and 2 g administered IV every 3 hours after the initial IV dose. MEASUREMENTS AND MAIN RESULTS: Cefazolin serum concentrations were collected after incision, after initiation of bypass, each hour of bypass, at the end of bypass, and at sternal closure. For patients weighing >120 kg undergoing cardiac surgery, the studied dosing regimen met or exceeded targeted cefazolin concentrations for all study patients. The authors conducted probability of target attainment analyses using both 65% and 100% of time with unbound drug concentrations across clinically relevant MICs. CONCLUSION: The authors found that their current dosing strategy achieved a probability of target attainment >90% throughout surgery for both total and unbound cefazolin concentrations, independent of cardiopulmonary bypass times.

Repair of Spontaneous Left Atrial Dissection Resulting in Severe Paravalvular Native Mitral Valve Regurgitation.

A 54-year-old male with history of end-stage renal disease secondary to hypertension on hemodialysis with moderate aortic valve insufficiency presented with progressive exertional dyspnea and lower extremity edema over several weeks. Relevant history included hospitalization for Staphylococcus epidermidis bacteremia secondary to dialysis catheter line infection 6 months prior. (Level of Difficulty: Advanced.).

Paravertebral analgesia in transapical transcatheter aortic valve replacement.

INTRODUCTION: Transapical transcatheter aortic valve replacement is an option for patients who are not candidates for traditional aortic valve surgery but have severe aortic stenosis and unfavorable ileo-femoral anatomy. Epidural analgesia in these cases has been associated with improved morbidity and mortality. The following manuscript presents the findings of an initial clinical experience employing paravertebral analgesia for patients undergoing transapical transcatheter aortic valve replacement. METHODS: A retrospective review was performed of 61 transapical transcatheter aortic valve replacement cases over a two-year period from November 2012 through July 2014. Paravertebral analgesia was provided as left sided single injections covering 1-3 dermatome levels using 0.2% ropivicaine with supplemental clonidine to 48 patients. The following outcome metrics were collected: 1) peri-operative opiate administration, 2) rate of extubation in the operating room, 3) new atrial fibrillation, 4) duration of intensive care stay, 5) 30-day mortality. RESULTS: The mean opiate administration was less in patients with paravertebral analgesia (128.65mcg vs. 163.46mcg fentanyl, p value 0.05) and these patients were more frequently extubated in the operating room (83.3% vs. 46.2%, p-value 0.0107). Incidence of atrial fibrillation was less in patients who received paravertebral analgesia (18.8% vs. 75.0%, p-value 0.0048). There was a non-significant trend towards decreased intensive care stay in patients who received paravertebral analgesia (58.3 hrs vs 75.8 hrs, p value 0.35). There was no difference in 30-day mortality. No complications resulted from paravertebral analgesia. CONCLUSIONS: This is the first reported case series of paravertebral blockade in transapical transcatheter aortic valve replacement  patients. The findings suggest that paravertebral single shot blocks are both safe and practical for use in this patient population. A formal prospective investigation of paravertebral analgesia in these patients is warranted.