A comparison of robot-assisted versus manually constructed endoscopic coronary anastomosis.

BACKGROUND: New technology has enabled surgeons to attempt totally endoscopic coronary artery bypass grafting. Our purpose was to compare three different techniques of totally endoscopic anastomosis using a porcine animal model. METHODS: Porcine hearts were excised and the right coronary artery was dissected free for use as an arterial graft. The hearts were placed in a human thoracic model and an endoscopic arterial anastomosis between the free right coronary artery and the left anterior descending coronary artery was performed using one of the following: (1) two-dimensional visualization with straight endoscopic instruments (n = 8); (2) three-dimensional head-mounted visualization with curved endoscopic instruments (n = 7); or (3) three-dimensional visualization with robotic telemanipulation (n = 8). Pathologic analysis of suture placement, vessel trauma, and patency was performed. Anastomoses were graded according to quality, ease, and patency using a seven-point Likert scale (1 = excellent, 7 = very poor). RESULTS: Endoscopic anastomotic ease and quality were significantly improved when three-dimensional visualization and curved endoscopic instruments were employed. Telemanipulation enhanced the process and provided the best operative results with regard to time required to construct the anastomosis, as well as ease and quality. CONCLUSIONS: Totally endoscopic anastomosis is feasible using currently available technology. Three-dimensional visualization and robotic telemanipulation significantly facilitate anastomosis construction and will likely benefit clinical operative outcome.

Cumulative sum failure analysis of a policy change from on-pump to off-pump coronary artery bypass grafting.

BACKGROUND: Use of the sequential probability cumulative sum (CUSUM) technique may be more sensitive than standard statistical analyses in detecting a cluster of surgical failures. We applied CUSUM methods to evaluate the learning curve after a policy change by a single surgeon from routine on-pump (cardiopulmonary bypass [CPB]) to off-pump coronary artery bypass grafting (OPCAB). METHODS: Fifty-five consecutive first-time coronary artery bypass patients (CPB group) were compared with the next 55 patients undergoing an attempt at routine OPCAB using the same coronary stabilizer. The goal in OPCAB patients was to obtain complete revascularization, albeit with a low threshold for conversion to CPB to maximize patient safety during the learning curve. Preoperative patient risk was calculated using previously validated models of the Cardiac Care Network of Ontario. The occurrence of operative mortality and nine predefined major complications (myocardial infarction, bleeding, stroke, renal failure, balloon pump use, mediastinitis, respiratory failure, life-threatening arrhythmia, and sepsis) was compared between the CPB and OPCAB groups using Wilcoxon, Fisher exact, and two-tailed t tests, as well as CUSUM methodology. An intention to treat analysis was performed. RESULTS: The CPB and OPCAB groups had similar predicted mortality and length of stays (2.2% +/- 2.5%, 8.1 +/- 2.5 days versus 2.4% +/- 3.5%, 8.1 +/- 2.4 days, respectively). The mean number of grafts per patient was 3.1 +/- 0.7 in the CPB group versus 3.0 +/- 0.7 in the OPCAB group (p = 0.45). Two of 55 (3.6%) CPB patients died, as opposed to 1 of 55 (1.8%) OPCAB patients (p = 0.99). Eight of 55 CPB patients (14.5%) incurred major complications, as opposed to 4 of 55 (7.3%) OPCAB patients (p = 0.36). Median hospital length of stay was 6.0 days in the CPB group versus 5.0 days in the OPCAB group (p = 0.28). On CUSUM analysis, the failure curve in CPB patients approached the upper 80% alert line after eight cases, whereas the curve in OPCAB patients reached below the lower 80% (reassurance) boundary 28 cases after the policy change, indicating superior results in the OPCAB group despite the learning curve. CONCLUSIONS: A policy change from coronary artery bypass on CPB to routinely attempting OPCAB can be accomplished safely despite the learning curve. CUSUM analysis was more sensitive than standard statistical methods in detecting a cluster of surgical failures and successes.

Steady flow visualization in a rigid canine aortic cast.

Steady flow studies were conducted in a transparent canine aortic cast. The cast segment stretched from the aortic valve to beyond the renal arteries and included all major branches. Flow was visualized by analysis of dye streaklines. Flow rates for basal and exercising cardiovascular states were simulated. The Reynolds numbers in the ascending aorta for basal and exercising conditions were 900 and 1587 respectively. Aortic core flow was laminar in basal simulations. Disturbed flow commenced in the upper descending aorta with exercising flow rates. Separation zones existed along the inner curvature of the aortic arch and the proximal walls of the brachiocephalic, left subclavian, and coeliac arteries. Such zones may exist over a portion of the cardiac cycle. If either renal artery was occluded, then a vortex formed. This vortex is associated with high shear regions which correlate well with sites where sudanophilic lesions have been reported in cholesterol-fed nephrectomized rabbits.

Aerospace air pollution issues.

Practitioners of aerospace medicine are mindful of the environmental effects, particularly air pollution, caused by aviation and spaceflight operations. To an aerospace medicine specialist, the environment includes not only the air, water, and soil of the earth, but also the cabin milieu of aircraft and space vehicles where crews must work, sleep, and in some cases, live. Consequently, this article will address the following areas of concern: cabin air quality of aircraft, cabin air quality of space vehicles, noise, air pollution, and aerial spraying.

Telemedicine and international disaster response. Medical consultation to Armenia and Russia via a Telemedicine Spacebridge.

UNLABELLED: The Telemedicine Spacebridge, a satellite-mediated, audio-video-fax link between four United States and two Armenian and Russian medical centers, permitted remote American consultants to assist Armenian and Russian physicians in the management of medical problems following the December 1988 earthquake in Armenia and the June 1989 gas explosion near Ufa. METHODS: During 12 weeks of operations, 247 Armenian and Russian and 175 American medical professionals participated in 34 half-day clinical conferences. A total of 209 patients were discussed, requiring expertise in 20 specialty areas. RESULTS: Telemedicine consultations resulted in altered diagnoses for 54, new diagnostic studies for 70, altered diagnostic processes for 47, and modified treatment plans for 47 of 185 Armenian patients presented. Simultaneous participation of several US medical centers was judged beneficial; quality of data transmission was judged excellent. CONCLUSION: These results suggest that interactive consultation by remote specialists can provide valuable assistance to on-site physicians and favorably influence clinical decisions in the aftermath of major disasters.

Telemedicine and international disaster response: medical consultation to Armenia and Russia via a Telemedicine Spacebridge.

UNLABELLED: The Telemedicine Spacebridge, a satellite-mediated, audio-video-fax link between four United States and two Armenian and Russian medical centers, permitted remote American consultants to assist Armenian and Russian physicians in the management of medical problems following the December 1988 earthquake in Armenia and the June 1989 gas explosion near Ufa. METHODS: During 12 weeks of operations, 247 Armenian and Russian and 175 American medical professionals participated in 34 half-day clinical conferences. A total of 209 patients were discussed, requiring expertise in 20 specialty areas. RESULTS: Telemedicine consultations resulted in altered diagnoses for 54, new diagnostic studies for 70, altered diagnostic processes for 47, and modified treatment plans for 47 of 185 Armenian patients presented. Simultaneous participation of several US medical centers was judged beneficial; quality of data transmission was judged excellent. CONCLUSION: These results suggest that interactive consultation by remote specialists can provide valuable assistance to on-site physicians and favorably influence clinical decisions in the aftermath of major disasters.

Health promotion: a perspective.

Although absolute proofs are sometimes lacking, advocates of health promotion tout physical fitness, proper nutrition, abstinence from smoking, and lower blood lipid levels, among others, as essential for a longer, healthier life. USAF implemented a Coronary Artery Risk Evaluation Program (CARE) several years ago and is now considering expanding it in scope in order to provide its beneficiaries with a comprehensive health promotion program. Although noncompliance, as well as philosophical/ethical issues, appears at times to be an obstacle, physicians should not be discouraged nor deterred.

Polycystic kidney disease and the flyer.

Polycystic kidney disease (PKD) is a disorder occasionally detected in aircrew members. Complications associated with PKD include hypertension, urinary tract infections and calculi, and cerebral or abdominal aneurysms with the most frequent cause of death, uremia and renal failure. The prognosis for PKD is variable in that it is a benign disorder for some patients whereas others are fraught with these complications. Many airmen with PKD can continue with cockpit duties as long as there are no potentially incapacitating symptoms. Of particular importance is good blood pressure control for those with hypertension.

Percutaneous nephrolithotomy and the flyer.

Percutaneous nephrolithotomy (PN) is a relatively new procedure that is coming in vogue for the removal of upper urinary tract stones. Although there are possible complications from the procedure--bleeding being the most common one--its advantages make it a desirable treatment modality vis-a-vis conventional surgery. This article describes the case of a pilot who underwent PN, but remained disqualified from flying status for 6 months because of an unfortunate complication.

Bleeding duodenal ulcer and the flier.

Over the years, the aeromedical disposition of aircrew members with bleeding duodenal ulcer has been a vexing problem because two essential questions cannot be categorically answered: Is the risk of rebleeding less with medical or with surgical treatment? In either case, is the risk of rebleeding low enough to permit, with reasonable prudence, the resumption of aircrew duties by the aviator? To try to answer these questions, the author has reviewed a portion of the literature and a number of medical records of patients with bleeding duodenal ulcer. With this information, the author draws his conclusions and offers recommendations for the aeromedical disposition of such aircrewmen.

Passenger safety, health, and comfort: a review.

Since the birth of aviation medicine approximately 80 yrs ago, practitioners and scientists have given their attention primarily to flight deck crew, cabin crew, and ground support personnel. However, in more recent years we have broadened our horizons to include the safety, health, and comfort of passengers flying commercial aircraft. This will be even more compelling as more passengers take to the air in larger aircraft and flying longer hours to more distant destinations. Further, we can expect to see more older passengers because people in many countries are living longer, healthier lives. The author first discusses the stresses imposed by ordinary commercial flight upon travelers such as airport tumult, barometric pressure changes, immobility, jet lag, noise/ vibration, and radiation. Medical considerations are next addressed describing inflight illness and medical care capability aboard U.S. air carriers. Passenger safety, cabin air quality, and the preventive medicine aspects of air travel are next reviewed in the context of passenger safety, health, and comfort. Recommendations are addressed to regulator agencies, airlines aircraft manufacturers, and the aerospace medicine community.

Inflight medical kits.

Great controversy surrounds the issue of United States (US) air carrier inflight medical kits. Although there are four medications mandated by the Federal Aviation Administration (FAA) that appeared to be adequate as determined by a 1988 survey, there is now a renewed call to review the medical kit contents with an eye toward making them more robust. This has been prompted by several well publicized inflight medical events and the fact that overseas airlines have a very wide array of pharmaceuticals and supplies. Consequently, the Aerospace Medical Association (AsMA) convened a Task Force of physicians across the major specialties to put forward recommendations regarding medication, medical supplies, and automatic external defibrillators (AEDs). These deliberations were based upon a survey of AsMA physician members.

Operation Homecoming: 25 years later.

Following an end to U.S. involvement in the Vietnam War in early 1973, approximately 600 Army, Navy, Air Force, and Marine personnel, the great majority aviators, were released from captivity in North and South Vietnam and Laos. Their initial medical evaluation was performed at USAF Hospital, Clark Air Base, Republic of the Philippines, between February and April 1973. The author describes the events of those memorable days.

Telemedicine: military applications.

Communications technology has enjoyed enormous growth in recent years and should be fully exploited by the medical community. Its application as part of disaster response was well demonstrated in the aftermath of the tragic earthquake in Soviet Armenia in 1988. Besides disaster response, telemedicine also has application for patient care, diagnostic imaging, and training and education. This capability would be particularly beneficial to the armed forces of many nations. If the communications equipment were portable, it could be well employed during peacetime, yet easily deployed to the battlefield. Therefore, armed forces should fully exploit telecommunications technology for the practice of military medicine.

Cambodian airlift.

To reduce the presence of U.S. military personnel in Cambodia, the Air Force, in September, 1974, completed negotiations with a civilian contractor to continue the emergency airlift of supplies and ammunition to that country. As the Khmer Rouge threat increased on the Cambodian capital, Phnom Penh, the airlift was expanded and the supply sorties increased. Because fatigue was a potential medical problem for the crews--they were required to fly excessive hours with little time off between 13 Jan. and 13 March, 1975--a flight surgeon was assigned to the company. The flight surgeon monitored the men by subjective evaluation, several physiological and hematological measurements, and anonymous questionnaires. Although none of the factors correlated with subjective fatigue or performance decrement, recommendations for aircrewmen flying emergency airlift operations in the future were made based upon this unique experience.

Negative transfer: a threat to flying safety.

Negative transfer is defined in the context of this paper as the transfer from one cockpit to another--of different design or configuration--of habits or responses which were appropriate in the former but are inappropriate in the latter, thereby posing a threat to flying safety. This danger has been demonstrated not only experimentally but also in a number of aircraft accident investigation reports. As new aircraft become available to the commercial, military, and private sectors and pilots consequently must transition from older to newer models, the phenomenon of negative transfer becomes increasingly significant. To illustrate the concept of negative transfer and aviation, the author compares the cockpits of two USAF aircraft and how their differences could adversely affect pilot performance. Recommendations are then made on ways organizational flight surgeons can minimize the negative transfer threat to aviation.

The prolapsed mitral valve syndrome and the flyer.

For the past 15 years there has been an increasing interest in the prolapsed mitral (PMV) syndrome as evidenced by its increasing attention in the literature. Although the syndrome in many of its aspects is still ill-defined, enough is known about it and its possible sequelae--arrhythmias, endocarditis, and sudden death--to signal some concern to flight surgeons. This paper briefly reviews the prolapsed mitral valve syndrome and defines the aeromedical problem which it presents. The author, furthermore, points out that there is a need for prospective studies so that the prognosis of PMV will be better understood. Only in that way will flight surgeons be able to determine more intelligently appropriate aeromedical disposition.

Sickle cell trait and the aviator.

Sickle cell trait (SCT) for years has been a controversial disorder within the aerospace medicine community. Some authorities consider SCT to be an entirely benign condition without particular significance, at least to moderate altitudes. Others are in disagreement and consider it a serious enough threat that flying duties should be precluded for all individuals with this disorder. These issues are addressed by reviewing SCT, its relationship to altitude, and its risk to aviation. The author concludes that flying organizations must establish their own policy on flying status for individuals with SCT based upon mission peculiarities and the assessment of risk inherent in that mission.

Smoke/fumes in the cockpit.

During the period 1970-80, there were reported in USAF 89 incidents of smoke/fumes in the cockpit during flight. The origin of the fumes in most cases was organic petroleum derivatives, which caused a multitude of symptoms including CNS dysfunction and mucous membrane irritation. Flight surgeons should be well-read in aerospace toxicology because of the threat to flying safety posed by the many fluids and substances necessary for the operation of today's modern aircraft.

Sudden incapacitation: USAF experience, 1970-80.

During the period 1970-80, there were reported 146 cases of in-flight sudden incapacitation in the USAF. Of these, 62 involved pilots, 14 were navigators, and 70 were student pilots. The etiologies of sudden incapacitation included illness without loss of consciousness, loss of consciousness, spatial disorientation, and improper M-1 maneuver. Each of these categories is analyzed with emphasis upon prevention, for example, not flying with symptomatic preexisting disease, continued emphasis upon spatial disorientation training, and correct performance of the M-1 maneuver. Based upon the data, conclusions and recommendations are suggested to minimize the risk of episodes of in-flight sudden incapacitation.