Further mechanical considerations between polar and SRM mobile ergometer systems during laboratory-based high-intensity, intermittent cycling activity.

The purpose of this article is to outline mechanical issues related to the use of the Polar S710 heart monitor with Power Unit when compared with the SRM Powercrank system. There are issues outlined in this article that refer to the suitability of the Polar S710 for the quantification of performance during downhill cycling that relate to chain vibration, chain tension, and time interval sampling rates.

Palladium-catalysed cross-coupling reactions in supercritical carbon dioxide.

Heck and Suzuki reactions proceed in good yield in supercritical carbon dioxide in the presence of palladium acetate and tri-tert-butylphosphine with both free and polymer-tethered substrates.

Valve surgery in octogenarians.

OBJECTIVE: To review the outcomes of octogenarians undergoing valve operations. PATIENTS AND METHODS: One hundred and twenty-five consecutive patients aged 80 years and over received valve operations between 1990 and 1996 at the Toronto General Hospital, Toronto, Ontario. All hospital survivors were prospectively followed for a mean of 36.6 months (range 0.1 to 89.9). RESULTS: One hundred and two patients received aortic valve operations, 18 patients received mitral procedures and five patients underwent double valve operations. Significant aortic stenosis was present in 95 of 102 patients (93%) receiving isolated aortic valve surgery, and mitral regurgitation was present in 16 of 18 patients (89%) undergoing mitral valve operations. Overall in-hospital mortality was 6.4% (n=8) and the perioperative infarction rate was 1.6% (n=2). In-hospital mortality was higher for mitral valve patients at 17% (n=3) than for aortic valve patients at 4% (n=4) (P=0.06). For the group overall, the six-year actuarial survival rate was 71.6+/-6%. The actuarial freedom from valve-related death was 97.1+/-2% at three years. Concomitant coronary artery disease was not significantly associated with perioperative mortality. Survivors had significantly improved New York Heart Association functional class status. CONCLUSION: In carefully selected patients aged 80 years and over, aortic valve surgery carries a low perioperative mortality with good intermediate term survival and benefits. Octogenarians undergoing mitral valve procedures experience higher perioperative mortality. Although the number of participants was small for this study, it does appear that coexistent coronary artery disease should not be the sole reason for denial of surgery because it has less of an impact on short and intermediate term survival than other factors.

Permanent cardiac pacing after a cardiac operation: predicting the use of permanent pacemakers.

BACKGROUND: The need for permanent cardiac pacing after cardiac operations is infrequent but associated with increased morbidity and resource utilization. We identified patient risk factors for pacemaker insertion to enable development of a predictive model. METHODS: Data were collected prospectively for 10,421 consecutive patients who had cardiac operations between January 1990 and December 1995. Two hundred fifty-five patients (2.4%) were identified as having received a permanent pacemaker during the same hospitalization. Logistic regression analysis was performed to determine the independent, multivariate predictors of permanent pacing. The predictive accuracy and precision of the logistic regression model was evaluated in the 1996 database of 2,236 consecutive patients by the calculation of Brier scores. RESULTS: Eight independent predictors of permanent pacemaker requirement were identified. The factor-adjusted odds ratios (OR) with 95% confidence interval (CI) associated with each predictor are as follows: (1) valve replacement surgery (aortic: OR 5.8, CI 3.9-8.7; mitral: OR 4.9, CI 3.1-7.8; tricuspid: OR 8.0, CI 5.5-11.9; double: OR 8.9, CI 5.5-14.6; and triple: OR 7.5, CI 2.9-19.3); (2) repeat operation: OR 2.4, CI 1.8-3.3; (3) age 75 years or older: OR 3.0, CI 2.0-4.4; (4) ablative arrhythmia operation: OR 4.2, CI 1.9-9.5; (5) mitral valve annular reconstruction: OR 2.4, CI 1.4-4.2; (6) use of cold blood cardioplegia: OR 2.0, CI 1.2-3.6; (7) preoperative renal failure: OR 1.6, CI 1.0-2.6; and (8) active endocarditis: OR 1.7, CI 0.9-3.0. A model for postoperative permanent pacemaker requirement using the eight predictors was formulated and tested (Brier score = 0.017+/-0.003; Z = 0.18). CONCLUSIONS: The proposed predictive model correlated highly with actual pacemaker use, which suggests that the requirement for pacing results from either operative trauma or increased ischemic burden. Preoperative identification of patients at increased risk of conduction disturbances may allow for earlier detection and improved treatment. Patients requiring postoperative pacing had increased morbidity and length of stay.

Ruptured splenic abscess secondary to infectious mononucleosis.

A 24-year-old woman with a recent diagnosis of infectious mononucleosis presented with fever and left upper quadrant pain. Abdominal computed tomography revealed a splenic abscess that at laparotomy was found to have ruptured. This case illustrates a rare cause of splenic abscess and a rare complication of infectious mononucleosis.

Acute jejunogastric intussusception: a rare cause of abdominal pain.

We report the case of a 61-year-old man with a history of a Bilroth II procedure who presented to the emergency department after 12 hours of severe epigastric pain and one episode of coffee-ground emesis. Computed tomography and esophagogastroduodenoscopy revealed intussuscepted jejunum through a gastrojejunostomy that required emergency operative reduction. This case illustrates the rare complication of acute jejunogastric intussusception more than 20 years after a Bilroth II procedure.

A cluster of sternal wound infections requiring muscle flap repair: problems in epidemiologic investigation.

A cluster of sternal wound infections (SWI) requiring muscle flap closure occurred in a California hospital in 1988. Review of SWI rates by surgical team revealed that a single team (Team A) was associated with a cluster of SWI requiring muscle flap repair (MFR). Team A's rate of SWI requiring MFR was 2.27% in 441 heart operations. A case/control study was conducted to determine if the higher rate of SWI requiring MFR could be attributed to disproportionately large numbers of patients at high risk treated by Team A. Data on major risk factors for SWI collected for case and control groups included the following: age at operation, weight, body surface area, history of obesity, diabetes mellitus, or cigarette smoking, duration of cardiopulmonary bypass, use of internal mammary artery graft, number of coronary arteries bypassed, use of prostheses, operating room staffing, and emergent nature of operation. No statistically significant differences between Team A cases requiring MFR and control cases were observed for predisposing risk factors. Surgical technique remains a principal suspected risk factor for SWI requiring MFR in this cluster.

Intussusception in the adult--a rare disease.

We present two cases of intussusception in the adult. Both cases were secondary to a benign lipoma as the lead point. These cases represent typical cases of adult intussusception, a rare disease characterized by insidious onset, vague abdominal symptoms, and elusive diagnosis. A diagnostic and therapeutic approach to adult intussusception is suggested. The need to consider this rare entity in the differential diagnosis of chronic abdominal complaints in the adult is emphasized.

Gastrostomy tube transmigration: a rare cause of small bowel obstruction.

A 77-year-old woman with an indwelling gastrostomy tube presented with a clinical picture of pneumonia and small bowel obstruction. During gastrostomy closure and performance of a feeding jejunostomy, inadvertent transmigration of the gastrostomy tube was found to be the etiology of the small intestinal obstruction. This case illustrates a rare complication of enteric feeding tubes.

Permanent internal pacemaker safety in air medical transport.

Helicopter and fixed-wing air medical transportation provides an important role in the management of critically-ill patients. As the use of cardiac pacemakers continues to grow, knowledge of their expanding capabilities and sophistication is important. The environments of our "airborne intensive care units" are subject to many sources of electromagnetic and vibrational interference. Although pacemaker shielding mechanisms have become quite elaborate, further studies are needed to define their reliability in modern aircraft. Further, the possible effects of electromagnetic and vibrational interference upon inflight reprogramming require further study.

Activity-sensing permanent internal pacemaker dysfunction during helicopter aeromedical transport.

STUDY OBJECTIVES: This study was designed to establish the frequency, magnitude, and possible etiologies of the dysfunction of activity-sensing internal pacemakers during helicopter aeromedical transport. DESIGN: Two models of Medtronic Activitrax pacemakers were attached externally to healthy adult volunteers. Each volunteer then was loaded into the helicopter and subjected to a flight sequence. Pacemaker firing rates throughout this sequence were recorded. SETTING: On separate days, Aerospatiale Dauphin and Twinstar helicopters completed a total of 23 flights. TYPE OF PARTICIPANTS: Four healthy adult volunteers, two men and two women, participated. INTERVENTIONS: These included intra- and inter-flight threshold re-programming and external magnet application. RESULTS: The average preflight pacemaker rate of 65 beats per minute increased to an average in-flight rate of 105 beats per minute, which resolved to preflight rates on shutdown. This pattern was consistently extinguished with external magnet application. CONCLUSION: The effect of rotor motion and flight vibration on the rate-response of the Activitrax pacemaker is both predictable and easily preventable. Possible guidelines for the safe transport of these patients, using pacemaker reprogramming or external magnet application, are examined.

Intracavernous carotid aneurysm--an unusual cause of isolated abducens nerve palsy.

We discuss the case of a 59-year-old woman who presented to the emergency department with complaints of diplopia for five days. Physical examination disclosed an isolated complete right abducens nerve palsy. Angiography revealed a giant aneurysm from the postcavernous portion of the right internal carotid artery. This case illustrates an unusual etiology of a unilateral abducens nerve palsy.

Taking to the skies.

The role of Helicopter EMS must be to improve patient care and/or to ensure the most rapid transport of critically ill or injured patients. It has been suggested by Rhee et al, that the aeromedical service can be justified when the speed of the helicopter transport, the skills of the medical crew, and/or the ability of the helicopter to overcome environmental obstacles is likely to contribute to improved patient outcome. If one adds the essentials of well-trained, professional personnel and equipment, the "helicopter" becomes an important part of the overall medical care system and an essential component in improving patient outcome. While reviewing the role of the HEMS, it cannot be sufficiently emphasized that such a service in no way replaces an established ground ambulance system. A proficient, well-trained and well-equipped ground EMS program remains the backbone of an efficient pre-hospital and interhospital system. HEMS cannot be viewed as an isolated component of any EMS system. Instead, it must serve to complement the existing resources of the community. These is sufficient literature to suggest that the use of air medical services in transporting patients to tertiary care facilities or trauma centers has led to an improvement in overall survival rates. At the same time, an apparent paradox in mortality rate has occurred at the receiving hospital. While more patients are saved by speedy transport to a hospital, the mortality rate in that hospital may actually increase. Some patients who may have died from their injuries at the scene, or in transit, now die upon admission.(ABSTRACT TRUNCATED AT 250 WORDS)