Jason Jenkins

Plasma and tissue pharmacokinetics of cefazolin in patients undergoing elective and semielective abdominal aortic aneurysm open repair surgery.

ABSTRACT Surgical site infections are common, so effective antibiotic concentrations at the sites of infection, i.e., in the interstitial fluid (ISF), are required. The aim of this study was to evaluate contemporary perioperative prophylactic dosing of cefazolin by determining plasma and subcutaneous ISF concentrations in patients undergoing elective/semielective abdominal aortic aneurysm (AAA) open repair surgery. This was a prospective pharmacokinetic study in a tertiary referral hospital. Cefazolin (2 g) was administered as a 3-min slow bolus 30 min prior to incision in 12 enrolled patients undergoing elective/semielective AAA open repair surgery. Serial blood, urine, and ISF (via microdialysis) samples were collected and analyzed using a validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. Cardiac output was determined using pulse waveform contours with Vigileo. The recruited patients had a median (interquartile range) age of 70 (66 to 76) years and weight of 88 (81 to 95) kg. The median (interquartile range) terminal volume of distribution was 0.14 (0.11 to 0.15) liter/kg, total clearance was 0.05 (0.03 to 0.06) liter/h, and minimum observed unbound concentration was 5.7 (5.4 to 8.1) mg/liter. The penetration of unbound drug from plasma to ISF was 85% (78% to 106%). We found correlations present, albeit weak, between cefazolin clearance and cardiac output (r2 = 0.11) and urinary creatinine clearance (r2 = 0.12). In conclusion, we found that a single 2-g dose of cefazolin administered 30 min before incision provides plasma and ISF concentrations in excess of the likely MICs for susceptible pathogens in patients undergoing AAA open repair surgery.

Predictors of outcome after elective endovascular abdominal aortic aneurysm repair and external validation of a risk prediction model

INTRODUCTION Endovascular abdominal aortic aneurysm (AAA) repair (EVAR) has been associated with lower operative mortality and morbidity than open surgery but comparable long-term mortality and higher delayed complication and reintervention rates. Attention has therefore been directed to identifying preoperative and operative variables that influence outcomes after EVAR. Risk-prediction models, such as the EVAR Risk Assessment (ERA) model, have also been developed to help surgeons plan EVAR procedures. The aims of this study were (1) to describe outcomes of elective EVAR at the Royal Brisbane and Womens Hospital (RBWH), (2) to identify preoperative and operative variables predictive of outcomes after EVAR, and (3) to externally validate the ERA model. METHODS All elective EVAR procedures at the RBWH before July 1, 2009, were reviewed. Descriptive analyses were performed to determine the outcomes. Univariate and multivariate analyses were performed to identify preoperative and operative variables predictive of outcomes after EVAR. Binomial logistic regression analyses were used to externally validate the ERA model. RESULTS Before July 1, 2009, 197 patients (172 men), who were a mean age of 72.8 years, underwent elective EVAR at the RBWH. Operative mortality was 1.0%. Survival was 81.1% at 3 years and 63.2% at 5 years. Multivariate analysis showed predictors of survival were age (P = .0126), American Society of Anesthesiologists (ASA) score (P = .0180), and chronic obstructive pulmonary disease (P = .0348) at 3 years and age (P = .0103), ASA score (P = .0006), renal failure (P = .0048), and serum creatinine (P = .0022) at 5 years. Aortic branch vessel score was predictive of initial (30-day) type II endoleak (P = .0015). AAA tortuosity was predictive of midterm type I endoleak (P = .0251). Female sex was associated with lower rates of initial clinical success (P = .0406). The ERA model fitted RBWH data well for early death (C statistic = .906), 3-year survival (C statistic = .735), 5-year survival (C statistic = .800), and initial type I endoleak (C statistic = .850). CONCLUSIONS The outcomes of elective EVAR at the RBWH are broadly consistent with those of a nationwide Australian audit and recent randomized trials. Age and ASA score are independent predictors of midterm survival after elective EVAR. The ERA model predicts mortality-related outcomes and initial type I endoleak well for RBWH elective EVAR patients.

Important observations made managing carotid body tumors during a 25-year experience

OBJECTIVES Our objective was to assess the short- and long-term outcome for patients after carotid body tumor (CBT) resection and discuss the potential pitfalls of the treatment. METHODS An analysis was undertaken of all patients who underwent CBT resection at Royal Brisbane and Womens Hospital and Greenslopes Private Hospital between 1982 and 2007. Primary tumor characteristics, surgical technique, and outcomes were recorded and analyzed. RESULTS A total of 49 consecutive CBT resections (2 recurrent tumors) were carried out in 39 patients (26 women [56%]) who were a mean age of 49 years (range, 17-75 years). A nontender neck mass was the presenting complaint in 85%, followed by screening in familial or contralateral tumors in 26%. Familial cases occurred in 11 patients (28%). There were no operative deaths. Complications occurred in 13 of the 49 operations (27%), predominantly temporary nerve palsies and were more likely to occur in tumors of large volume or in cases of removal of coexisting vagal tumors. Malignant disease was present in seven cases (15%). All patients have been followed-up postoperatively for a mean of 11 years (range, 2-26 years). Metachronous paragangliomas have been discovered in six patients, all with familial disease. CONCLUSIONS Early resection of carotid body tumors should be undertaken while still small to minimize the risk of neural injury, which increases with tumor size. In cases of bilateral CBT, we recommend that the smaller tumor be resected first, before the staged resection of the larger contralateral tumor. In familial or bilateral tumor cases, other synchronous and metachronous paragangliomas should be excluded. Mandatory lifelong follow-up is essential.

Mycotic Carotid Pseudoaneurysm: Staged Endovascular and Surgical Repair

Mycotic carotid pseudoaneurysms are rare and challenging to manage. Traditional surgical approaches are technically demanding and can be associated with a high morbidity and mortality. The use of endovascular stents in infected fields remains controversial, and long-term efficacy has not been fully clarified. We describe a case where a combined staged endovascular and open surgical approach was used to successfully manage a mycotic carotid pseudoaneurysm that developed following dental extraction. A covered endovascular stent was used to temporarily exclude the infected pseudoaneurysm, before proceeding to early definitive surgical management. We suggest that staged endovascular therapy followed by early surgical repair should be considered for this difficult surgical problem.

Long-term outcomes and factors influencing late survival following elective abdominal aortic aneurysm repair: a 24-year experience

Background Abdominal aortic aneurysms can be either treated by an open abdominal aortic aneurysm repair or an endovascular repair. Comparing clinical predictors of outcomes and those which influence survival rates in the long term is important in determining the choice of treatment offered and the decision-making process with patients. Aims To determine the influence of pre-existing clinical predictors and perioperative determinants on late survival of elective open abdominal aortic aneurysm repair and endovascular repair at a tertiary hospital. Methods Consecutive patients undergoing elective abdominal aortic aneurysm repair from 1990 to 2013 were included. Data were collected from a prospectively acquired database and death data were gathered from the Queensland state death registry. Pre-existing risks and perioperative factors were assessed independently. Kaplan–Meier and Cox regression modeling were performed. Results During the study period, 1340 abdominal aortic aneurysms were repaired electively, of which 982 were open abdominal aortic aneurysm repair. The average age was 72.4 years old and 81.7% were males. The cumulative percentage survival rates for open abdominal aortic aneurysms repair at 5, 10, 15 and 20 years were 79, 49, 31 and 22, respectively. The corresponding 5-, 10- and 15-year survival rates for endovascular repair were not significantly different at 75, 49 and 33%, respectively (P = 0.75). Predictors of reduced survival were advanced age, American Society of Anaesthesiology scores, chronic obstructive pulmonary disease, renal impairment, bifurcated grafts, peripheral vascular disease and congestive heart failure. Conclusions Open repair offers a good long-term treatment option for patients with an abdominal aortic aneurysm and in our experience there is no significant difference in late survival between open abdominal aortic aneurysms repair and endovascular repair. Consideration of the factors identified in this study that predict reduced long-term survival for open abdominal aortic aneurysms repair and endovascular repair should be considered when deciding repair of abdominal aortic aneurysm.

The pharmacokinetics of cefazolin in patients undergoing elective & semi-elective abdominal aortic aneurysm open repair surgery

BackgroundSurgical site infections are common, so effective antibiotic concentrations at the sites of infection are required. Surgery can lead to physiological changes influencing the pharmacokinetics of antibiotics. The aim of the study is to evaluate contemporary peri-operative prophylactic dosing of cefazolin by determining plasma and subcutaneous interstitial fluid concentrations in patients undergoing elective of semi-elective abdominal aortic aneurysm (AAA) open repair surgery.Methods/DesignThis is an observational pharmacokinetic study of patients undergoing AAA open repair surgery at the Royal Brisbane and Womens Hospital. All patients will be administered 2-g cefazolin by intravenous injection within 30-minutes of the procedure. Participants will have samples from blood and urine, collected at different intervals. Patients will also have a microdialysis catheter inserted into subcutaneous tissue to measure interstitial fluid penetration by cefazolin. Participants will be administered indocyanine green and sodium bromide as well as have cardiac output monitoring performed and tetrapolar bioimpedance to determine physiological changes occurring during surgery. Analysis of samples will be performed using validated liquid chromatography tandem mass-spectrometry. Pharmacokinetic analysis will be performed using non-linear mixed effects modeling to determine individual and population pharmacokinetic parameters and the effect of peri-operative physiological changes on cefazolin disposition.DiscussionThe study will describe cefazolin levels in plasma and the interstitial fluid of tissues during AAA open repair surgery. The effect of physiological changes to the patient mediated by surgery will also be determined. The results of this study will guide clinicians and pharmacists to effectively dose cefazolin in order to maximize the concentration of antibiotics in the tissues which are the most common site of surgical site infections.

The predictive accuracy of the american college of surgeons national surgical quality improvement program surgical risk calculator in patients undergoing major vascular surgery

Aim: The American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP) Surgical Risk Calculator (SRC) was developed to estimate the rates of complications for patients undergoing a variety of surgical procedures, based on the patients preoperative demographics and medical conditions. Its predictive ability has been evaluated in a number of studies for a variety of surgical fields. There has so far been no assessment of the SRC in patients undergoing vascular surgery. This study assesses whether the ACS NSQIP SRC can accurately predict risk of complications in patients undergoing major vascular surgery at a tertiary hospital. Methods: A retrospective review of prospectively collected data was performed on all patients who underwent an open abdominal aortic aneurysm (AAA) repair, an endovascular aneurysm repair (EVAR), or a femoral-popliteal bypass graft (FPBG) from July 2016 to April 2017. A total of 95 patients had their demographics entered into the ACS NSQIP SRC, and the predicted rates of complications were compared to the observed rates of complications. Results: Statistical analysis was performed with Brier scores and C-statistics. This analysis found the ACS NSQIP SRC accurately estimated the risk of complications with a Brier score of 0.044 for EVAR, 0.068 for open AAA repair, and 0.0752 for FPBG. The C-statistics for serious complications, any complications, and discharge to a nursing home or rehabilitation indicated the model was good at accurately predicting the risk of these outcomes. Conclusion: The ACS NSQIP SRC accurately predicts the rates of complications in patients undergoing vascular surgery.

Extra-Anatomic Axillo-Mesenteric Reconstruction for Chronic Mesenteric Ischemia.

We present a case of extra-anatomic axillo-mesenteric reconstruction for chronic mesenteric ischemia. Endovascular access and retrograde bypass options were prohibited by severe aortoiliac occlusive disease. Standard antegrade bypass was impossible because of the presence of a thoracoabdominal aortic aneurysm. This unusual method of mesenteric reconstruction is a robust and viable option for patients with challenging anatomy and multiple comorbidities that preclude traditional endovascular and open surgical options.

A Right Intercosto-Bronchial Artery Derived from the Thyrocervical Trunk: An Unusual Cause of Type II Endoleak Post Thoracic Aortic Stenting

The aetiology, incidence and management of type II endoleaks in standard infrarenal endovascular aortic aneurysm repair is well described. Far less data is available for thoracic stent grafting. We present a rare and interesting case of a type II endoleak post thoracic aortic stenting and highlight the aberrant anatomy that can cause this phenomenon in such cases.