Intraoperative findings on ECAP-measurement: Normal or special case?

Objective: This study aimed to investigate the measurability and threshold level of electrically evoked compound action potentials (ECAPs) in order to provide a baseline for the development of diagnostic references to support aftercare procedures. Design: In this retrospective study, cochlear implant patients were grouped according to the electrode array type and preoperative diagnostic findings from radiological imaging. ECAP measurements were performed intraoperatively on 22 electrodes for each patient resulting in two comparisons: (1) normal vs. pathological findings based on imaging with same electrode array, (2) perimodiolar electrode vs. straight electrode array within the normal group. Study sample: The study sample consisted of 218 ears with a Nucleus^® implant. Results: In the group with normal radiological imaging, the percentage of measurable ECAPs was higher than in the pathological group. The ECAP thresholds on 21 electrodes were significantly different between the two groups. Furthermore the thresholds were significantly lower for basal electrodes mainly for the two different electrode types. Conclusion: The pathological changes in the inner ear, the type of electrode array, and the electrode position affect the ECAP threshold. Further consideration suggests that a receiver operating characteristic curve can be derived from the results.     

Characterization of 75:25 poly(l-lactide-co-epsilon-caprolactone) thin films for the endoluminal delivery of adipose-derived stem cells to abdominal aortic aneurysms

Abdominal aortic aneurysms occur in 5-7% of men over the age of 60 and their incidence is rising. Current therapies remove the affected tissue or prevent blood flow through the aneurysm, but do not repair the underlying structural changes of the vascular wall. Adipose tissue derived stem cells (ADSCs) seeded on a biodegradable thin film and delivered endoluminally to the aneurysm site could potentially repair the vessel wall, preventing growth and rupture of the aneurysm. In this study, the mechanical and degradation properties of a novel 75:25 poly(l-lactide-co-epsilon-caprolactone) (PLCL) thin film, as well as, the effects of different surface structures on stem cell adherence and resistance to shear stress was investigated. It was possible to reproducibly create films of consistent physical properties. These films degraded approximately 50% in 6 month, which would be a sufficient time to allow cells to engraft in the aortic wall. Ethylene oxide treatment significantly increased the stiffness and yield stress of the films, which exhibit >700% elongation. Treatment of the films with NaOH and HCl induced the formation of surface texture on the films; however, this texture did not affect stem cell adherence or resistance to delamination by shear stress when compared to nontreated or fibronectin-coated films. These results indicate that PLCL thin films have a sufficient degradation time and mechanical strength to serve as a scaffold in vivo for ADSCs, and that ADSCs seeded on the thin film can withstand a range of physiologic shear stresses.     

Chronic AT1-receptor blockade does not alter cerebral oxygen supply/demand ratio during cardiopulmonary bypass in hypertensive patients

Background: The angiotensin II receptor type 1 antagonist candesartan has been hypothesized to alter vasopressor requirements and brain–blood flow by changing cerebrovascular autoregulation. Therefore, we assessed the effects of a pre-anaesthetic treatment course with candesartan on cerebral arterial-jugular bulb oxygen content difference, middle cerebral artery blood velocity, and vasopressor requirements in hypertensive patients undergoing elective on-pump coronary artery bypass graft surgery.
Methods: In a randomized, double-blind, placebo-controlled study, we evaluated the effects of candesartan (8 mg po/d, given for 6–8 days before surgery) in 35 hypertensive patients. The mean arterial pressure was maintained above 60 mmHg by bolus administration of phenylephrine, if required, and dosages were recorded.
Results: Candesartan did not significantly alter oxygen content difference across the cerebral circulation, mean middle cerebral artery blood velocity during cardiopulmonary bypass, or phenylephrine requirements either before (0.0067 μg/kg/min±0.0042 vs. 0.0056 μg/kg/min±0.0049, P =0.48) or during cardiopulmonary bypass (0.0240 μg/kg/min±0.0240 vs. 0.0250 μg/kg/min±0.0190, P =0.97) compared with placebo.
Conclusion: Thus, a 6–8-day treatment course with candesartan does not alter global cerebral perfusion and oxygen supply/demand ratio during cardiopulmonary bypass, or vasopressor requirements in hypertensive patients undergoing on-pump coronary artery bypass graft surgery, and no deleterious consequences of AT1-receptor blockade were detected.     

Predictors and outcome of gastrointestinal complications in patients undergoing cardiac surgery

OBJECTIVE: To determine the incidence and independent predictors of gastrointestinal complications (GICs) following cardiac surgery. SUMMARY BACKGROUND DATA: Gastrointestinal ischemia and hemorrhage represent a rare but devastating complication following heart surgery. The profile of patients referred for cardiac surgery has changed during the last decade, questioning the validity of previously reported incidence and risk factors. METHODS: We retrospectively analyzed prospectively collected data from 4819 patients undergoing cardiac surgery between 1998 and 2004. Patients with GICs were compared with the entire patient population. Study endpoints were mortality, postoperative morbidities, and long-term survival. RESULTS: GICs occurred in 51 (1.1%) patients. Etiologies were intestinal ischemia (n = 30; 59%) and hemorrhage (n = 21; 41%). The incidence decreased during the study period (1998-2001: 1.3%, 2002-2004: 0.7%; P = 0.04). The incidence per type of procedure was as follows: coronary artery bypass grafting (CABG)/valve (2.4%), aortic surgery (1.7%), valve surgery (1.0%), and CABG (0.5%; P = 0.001). Multivariate analysis revealed age (odds ratio [OR] = 2.1), myocardial infarction (OR = 2.5), CHF (OR = 2.4), hemodynamic instability (OR = 2.8), cardiopulmonary bypass time >120 minutes (OR = 6.2), peripheral vascular disease (OR = 2.2), renal (OR = 3.2), and hepatic failure (OR = 10.8) as independent predictors of GICs. The overall hospital mortality among patients with GICs was 33%. Long-term survival was significantly decreased in patients with GICs compared with the control group. CONCLUSIONS: Gastrointestinal complications following cardiac surgery remain rare with an incidence <1% in a contemporary series. The key to a lower incidence of GICs lies in systematic application of preventive measures and new advances in intraoperative management. Identification of independent risk factors would facilitate the determination of patients who would benefit from additional perioperative monitoring. Future resources should therefore be redirected to mitigate GICs in high-risk patients.