Michael Bourke

The cardiac anesthesia risk evaluation score: a clinically useful predictor of mortality and morbidity after cardiac surgery.

BackgroundThe Cardiac Anesthesia Risk Evaluation (CARE) score is a simple risk classification for cardiac surgical patients. It is based on clinical judgment and three clinical variables: comorbid conditions categorized as controlled or uncontrolled, surgical complexity, and urgency of the procedure. This study compared the CARE score with the Parsonnet, Tuman, and Tu multifactorial risk indexes for prediction of mortality and morbidity after cardiac surgery. MethodsIn this prospective study, 3,548 cardiac surgical patients from one institution were risk stratified by two investigators using the CARE score and the three tested multifactorial risk indexes. All patients were also given a CARE score by their attending cardiac anesthesiologist. The first 2,000 patients served as a reference group to determine discrimination of each classification with receiver operating characteristic curves. The following 1,548 patients were used to evaluate calibration using the Pearson chi-square goodness-of-fit test. ResultsThe areas under the receiver operating characteristic curves for mortality and morbidity were 0.801 and 0.721, respectively, with the CARE score rating by the investigators; 0.786 and 0.710, respectively, with the CARE score rating by the attending anesthesiologists (n = 8); 0.808 and 0.726, respectively, with the Parsonnet index; 0.782 and 0.697, respectively, with the Tuman index; 0.770 and 0.724 with the Tu index, respectively. All risk models had acceptable calibration in predicting mortality and morbidity, except for the Parsonnet classification, which failed calibration for morbidity (P = 0.026). ConclusionsThe CARE score performs as well as multifactorial risk indexes for outcome prediction in cardiac surgery. Cardiac anesthesiologists can integrate this score in their practice and predict patient outcome with acceptable accuracy.

The patient with a pacemaker or related device

SummaryPatients with implanted pacemakers and ICDs can be safely managed for surgery and anaesthesia. Anaesthetic management of such patients should be planned first according to the patient’s underlying medical status with particular emphasis on ventricular function and electrolyte balance.The anaesthetist must understand the various modes of pacemakers and ICDs available in the patient population. These devices are safe and well shielded form most electromagnetic interference in the operating room. Some precautions are nevertheless necessary. A magnet should not be placed routinely over a programmable pacemaker or ICD in the operating room, especially in the presence of electrocautery. Rate-responsive pacemakers should have rate adaptive modes disabled before surgery whenever possible. The mechanism of rate response should be known, so that inappropriate changes in heart rate can be avoided in the perioperative period if the rate responsive mode cannot for some reason be disabled. Antitachycardia pacemakers, should have the antitachycardia function disabled preoperatively. Methods for the provision of alternate emergency pacing should be available when dealing with patients at risk of bradyarrhythmias or pacemaker failure in the operating room. The anaesthetist should have a safe, practical plan of action that suites his/her experience and capabilities.ICDs should have automatic cardioverter-defibrillator functions disabled for surgery and external modes of cardioversion/defibrillation should be available.RésuméL’anesthésie et la chirurgie des patients porteurs de pacemaker et de CDI peuvent être réalisée en toute sécurité. La gestion anesthésique de ces patients doit être planifiée en tenant compte de la condition médicale sous-jacente et en portant une attention particulière à la fonction ventriculaire et à l’équilibre électrolytique. L’anesthésiste doit connaître les différents modes de fonctionnement des pacemakers et des CDI disponibles. Ces appareils sont éprouvés et blindés efficacement contre la plupart des interférence électromagnétiques propres à la salle d’opération. En général, un aimant ne doit pas être placé au regard du pacemaker et du CDI en salle d’opération, surtout lorsqu’on utilise l’électrocautère. On devrait désactiver le mode sentinelle des pacemakers de ce type lorsque c’est possible. Son mécanisme doit être connu de façon à éviter les changements inappropriés de fréquence cardiaque à la période opératoire, si pour une raison ou une autre, on ne peut désactiver le mode sentinelle. La fonction antitachycardie des pacemakers qui opèrent selon ce mode doit être inactivée avant l’intervention. Des méthodes de rechange pour l’entraînement d’urgence doivent être disponibles lorsqu’on a la charge de patients à risque de bradyarythmies ou lors d’une panne du pacemaker en salle d’opération. L’anesthésiste doit avoir un plan d’action sûr et pratique adapté à son expérience et sa compétence.Il faut désactiver le fonction de cardioversion-défibrillation automatique des CDI avant l’intervention et avoir à portée de main ce qu’il faut pour la cardioversion/défibrillation externe.

Catheter-induced pulmonary artery false aneurysm and rupture: Case report and review

REAS MANY believe that information derived from the pulmonary artery catheter (PAC) is crucial for the diagnosis and quantification of cardiovascular dysfunction, there are those who think it contributes to morbidity and mortality.lJ Persons performing pulmonary artery (PA) catheterization must therefore be cognizant of iatrogenic problems related to the catheter in order to avoid preventable adverse outcomes.3 The most feared complication is perforation of the PA, which is estimated to occur in 0.06% to 0.2% of cases but which carries a mortality rate of 45% to 65%.4,5 Delayed hemorrhage resulting from rupture of catheter-induced pulmonary artery false aneurysms (PAPAs) has been described but reported to be rare.6 A Medline search of virtually all cases reported in the English literature through August 1992 indicates that the high morbidity and mortality associated with this delayed complication have not been fully appreciated. A case is reported of catheter-induced PAPA and rupture and the current knowledge of this complication is reviewed.

Using prospective clinical surveillance to identify adverse events in hospital

Background To improve patient safety, organisations must systematically measure avoidable harms. Clinical surveillance—consisting of prospective case finding and peer review—could improve identification of adverse events (AEs), preventable AEs and potential AEs. The authors sought to describe and compare findings of clinical surveillance on four clinical services in an academic hospital. Methods Clinical surveillance was performed by a nurse observer who monitored patients for prespecified clinical events and collected standard information about each event. A multidisciplinary, peer-review committee rated causation for each event. Events were subsequently classified in terms of severity and type. Results The authors monitored 1406 patients during their admission to four hospital services: Cardiac Surgery Intensive Care (n=226), Intensive Care (n=211), General Internal Medicine (n=453) and Obstetrics (n=516). The authors detected 245 AEs during 9300 patient days of observation (2.6 AEs per 100 patient days). 88 AEs (33%) were preventable. The proportion of patients experiencing at least one AE, preventable AE or potential AE was 13.7%, 6.1% and 5.3%, respectively. AE risk varied between services, ranging from 1.4% of Obstetrics to 11% of Internal Medicine and Intensive Care patients experiencing at least one preventable AE. The proportion of patients experiencing AEs resulting in permanent disability or death varied between services: ranging from 0.2% on Obstetrics to 4.9% on Cardiac Surgery Intensive Care. No services shared the most frequent AE type. Conclusions Using clinical surveillance, the authors identified a high risk of AE and significant variation in AE risks and subtypes between services. These findings suggest that institutions will need to evaluate service-specific safety problems to set priorities and design improvement strategies.

Surgical Treatment of Chronic Thromboembolic Pulmonary Hypertension

BACKGROUND There are only limited treatment options for patients with chronic thromboembolic pulmonary hypertension in Canada. OBJECTIVE To conduct a case-series study to assess the effectiveness of surgical endarterectomy of the pulmonary artery. DESIGN AND SETTING Twenty-one patients with chronic thromboembolic pulmonary hypertension were admitted for surgery between July 1995 and October 1999. Clinical, laboratory and radiological data were collected for all patients who then underwent pulmonary thromboendarterectomy. MAIN RESULTS Thirteen men and eight women between 22 and 71 years of age underwent surgery. The main presenting complaint was dyspnea on exertion. Pulmonary vascular resistance ranged from 382 to 1694 dynes s cm-5 with a mean of 765+/-372 dynes s cm-5 (normal is less than 180 dynes s cm-5) with a mean cardiac index of 2.2+/-0.9 L/min/m2. Two patients had concomitant tricuspid valve replacement and one patient had coronary bypass grafting. In three cases, the surgery involved a repeat sternotomy. After surgery, there was a significant drop in the pulmonary vascular resistance (208+/-92 dynes s cm-5, P<0.05) and a concomitant rise in the cardiac index to a mean of 3.1+/-0.6 L/min/m2 (P<0.05). There was one death in a patient who also had severe chronic obstructive pulmonary disease. Of the remaining patients, all but two showed significant clinical improvement. Spiral computed tomography postsurgery demonstrated improvement in pulmonary perfusion with either complete clearing or significant improvement in the mosaic perfusion pattern. Right ventricular function and pressure on echocardiogram improved in all but two patients. CONCLUSIONS Pulmonary thromboendarterectomy provides effective treatment for chronic thromboembolic pulmonary hypertension.

Uterine tumor in the heart: Intravenous leiomyomatosis

INTRAVENOUS LEIOMYOMATOSIS OF THE UTERUS is a rare clinical enti ty cha rac t e r i zed by in t r avenous ex t ens ion o f a s m o o t h musc le t u m o r o r ig ina t ing in the uterus. Earliest r epo r t s o f this c o n d i t i o n da te back to the b e g i n n i n g o f this century. 1 Occasional ly these t umor s do n o t b e c o m e symptomat i c be fo r e e x t e n d i n g in to t he hear t . We p r e s e n t o n e such case and a review o f the l i te ra ture o f in t ravenous l e iomyomatos i s with cardiac ex tens ion . A discussion o f the d iagnos is a n d surgical t r e a t m e n t o f this les ion is p r e s e n t e d .

Pancuronium or vecuronium for treatment of shivering after cardiac surgery

This randomized double-blind study compared the hemodynamic and metabolic effects of pancuronium and vecuronium during treatment of shivering after cardiac surgery with hypothermic cardiopulmonary bypass. Thirty sedated and pain-free patients who shivered after cardiac surgery were treated with pancuronium (n = 15) or vecuronium (n = 15) 0.08 mg/kg. Baseline values of heart rate (HR), mean arterial pressure, arterial and venous blood gases, total body oxygen consumption indexed to body surface area (VO2-I), and pressure work index (PWI, an estimate of myocardial oxygen consumption) were measured on arrival in the intensive care unit, at onset of shivering, and repeatedly for 2 h after treatment. Continuous ST segment analysis of leads II and V5 were used for detection of myocardial ischemia. Treatment of shivering with pancuronium decreased VO2-I by 32% (P = 0.0001). This was accompanied by a 14% increase in HR (P = 0.001) and a 10% increase in PWI (P = 0.03). Vecuronium decreased VO2-I by 36% (P = 0.003) with a 4% decrease in HR (P = 0.04) and a 6% decrease in PWI (P = 0.06). Myocardial ischemia (n = 3) and ventricular arrhythmias (n = 3) occurred in five patients treated with pancuronium. Only one patient treated with vecuronium had ventricular arrhythmia (P = 0.08). Seven patients treated with pancuronium and eight treated with vecuronium were taking beta-adrenergic blockers preoperatively which was associated with lower HR (96 +/- 16 vs 109 +/- 15 bpm; P = 0.025) and lower PWI (8.8 +/- 1.2 vs 10.7 +/- 1.92 mL.min-1 x 100 g-1; P = 0.003) at onset of shivering. However, beta-adrenergic blockers did not attenuate the relative HR increase induced by pancuronium. No relationship was found between hypercapnia and tachycardia or hypertension. These results suggest that, when compared to pancuronium for treatment of postoperative shivering, vecuronium may be advantageous because it does not increase myocardial work. The disproportionate relationship between VO2-I and PWI after treatment with muscle relaxants indicates that increased VO2-I does not contribute significantly to the hemodynamic disturbances associated with shivering. These disturbances are more likely the results of increased adrenergic activity related to pain and recovery from anesthesia. Shivering and its associated hemodynamic disturbances appear to be concomitant but independent signs of awakening.

Is Bilateral Internal Thoracic Artery Use Safe in the Elderly

Abstract  Background: The strategy of bilateral mammary artery grafting is often not considered for elderly patients due to perceived concerns of increased morbidity and mortality. The objective of this study is to explore the safety of bilateral mammary in elderly patients.Methods: Out of 7746 patients who underwent coronary artery bypass grafting using at least one internal thoracic artery (ITA), there were 3940 patients aged 65 years or greater, and of those, 3581 patients had a single ITA (SITA) and 359 patients had bilateral ITAs (BITAs). The primary outcome was the incidence of major adverse cardiac or cerebrovascular events (MACCEs). Secondary outcomes included re‐exploration for bleeding, blood transfusions, sternal wound infections, and intensive care unit and hospital length of stay. Results: The incidence of mortality and MACCE were similar in both groups (mortality BITA 2.6%, SITA 3.6%, p = 0.25, MACCE BITA 8.5%, SITA 6.1%, p = 0.13). Superficial and deep sternal site infections were significantly more prevalent in the BITA group than the SITA group [superficial OR 0.42, 95% CI [0.23 – 0.75] (p = 0.003) and deep OR 0.29, 95% CI [0.14 – 0.58 (p = 0.0005)]. Conclusion: Use of BITA is safe in the elderly with respect to mortality and early cardiovascular outcome. BITA use in the elderly is associated with an increased risk of sternal wound infection. Our experience in this situation suggests that there is a maximum age (approximately 74 years) beyond which the combined risk of MACCE and wound complications supersedes the benefits in terms of sternal infections. (J Card Surg 2012;27:1‐5)

The HeartSaver left ventricular assist device: an update

BACKGROUND Ventricular assist devices have been shown to be effective as bridges to transplantation and recovery for patients with end-stage heart failure. Current technology has been limited because of the need for percutaneous connections with controllers. The HeartSaver ventricular assist device (VAD) (World Heart Corporation, Ottawa, Ontario, Canada) was developed with the intention of having a completely implantable, portable VAD system. The system consists of an electrohydraulic blood pump, internal and external battery power, and a transcutaneous energy transfer and telemetry unit that allows for power transmission through the skin. Control of the device may be achieved locally or remotely through a variety of communication systems. METHODS The device has been modified with the Series II preclinical version being available for in vitro (mock loop) and in vivo (bovine model) testing. RESULTS Seventeen Series II devices have been functional on mock loops or other testing trials for an accumulated 900 days of operation. There have been eight acute experiments using a bovine model to test various components as they have become available from manufacturing. Mean pump output was 10.4 +/- 1.1 L/min in full-fill/full-eject mode. Changes in the last 24 months include (1) cannula redesign for better port alignment and integration of tissue valves; (2) battery redesign to convert to new lithium-ion cells; (3) optimized infrared information and electromagnetic inductance energy transmission through various skin thicknesses and pigmentation; and (4) improved reliability of internal and external controller hardware and software. CONCLUSIONS Modifications have been required to optimize the HeartSaver VADs performance. The final HeartSaver VAD design will be produced in the near future to allow for formal in vitro and in vivo testing before clinical implantation.

Intravenous nifedipine to treat hypertension after coronary artery revascularization surgery. A comparison with sodium nitroprusside.

We administered sodium nitroprusside (SNP) or nifedipine intravenously to patients who became hypertensive after elective coronary revascularization and compared their effects on hemodynamics and the electrocardiogram in a parallel, randomized, open-label study. Four of 21 patients treated with nifedipine required the addition of SNP to maintain mean arterial pressure less than 90 mm Hg, compared with 4 of 28 patients in the SNP group who required the addition of nifedipine. The success rates of nifedipine (81%) and SNP (86%) were not significantly different. There was no difference in the incidence of adverse ST-segment changes during drug infusion (4% versus 5%) or perioperative myocardial infarction (9.5% versus 10.7%) in the nifedipine versus SNP groups, respectively. The plasma nifedipine concentration (mean value +/- SD) at steady state for 21 patients receiving nifedipine was 119 +/- 42.5 ng/mL. The pharmacokinetic variables for nifedipine were as follows (mean values +/- SD): systemic clearance, 0.525 +/- 0.228 L.h-1.kg-1; apparent volume of distribution, 0.738 +/- 0.446 L/kg; and elimination half-life, 1.02 +/- 0.51 h. These values are similar to those reported previously in healthy volunteers. We conclude that intravenous nifedipine can be used safely to control hypertension after coronary revascularization but were unable to demonstrate an advantage of nifedipine compared with SNP in preventing postoperative ischemia or infarction in this group of patients who had good left ventricular function.