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Biomedical subjects

J S Kirkland

Publications and source records attributed to J S Kirkland.

11 recordsLinked to original sources
PubMed1995

Angioplasty with stent placement in peripheral arterial occlusive disease.

Percutaneous transluminal balloon angioplasty (PTBA) is a minimally invasive and effective adjunct treatment for patients with atherosclerotic peripheral vascular disease. This surgical technique involves placing an intraarterial balloon within an obstructing arterial lesion and forcibly dilating the balloon under fluoroscopy. The PTBA technique has become an accepted interventional therapy for iliac artery stenoses. In selected patients with stenotic lesions of the iliac artery, percutaneous transluminal angioplasty (PTA) with the use of an intravascular stent may be an alternative to traditional aortofemoral bypass surgery. The PTA procedure involves only a needle entry site in one or both groins as opposed to an incision exposing the entire abdomen. The hospital stay for the average patient undergoing PTA of the iliac artery is three days as opposed to seven days for the patient undergoing aortofemoral bypass, and the patient may return to normal activity in a much shorter period of time after a PTA procedure.

Angioplasty, Balloon↗
PubMed1986

In situ saphenous vein bypass for occlusive disease in the lower extremity.

In situ saphenous vein bypass, using the new valve incision techniques, has shown great promise in the early clinical trials to date. This procedure allows disruption of the venous valves without removal of the vein from its bed, thus allowing preservation of the vasa vasorum and maintenance of the endothelial integrity of the veins. This has allowed an overall improvement in the patency rates of the lower extremity bypasses, particularly in the bypasses to the infrapopliteal position. Also, and perhaps most important, it has permitted the use of smaller veins, with a minimum diameter of 2 mm. This greatly increases the number of patients who can benefit from such a vein bypass since reversed vein bypasses previously have required veins to have a minimum diameter of 3.5 to 4 mm. Long-term follow-up of in situ bypasses is not yet available. However, if the encouraging preliminary results of these bypasses are substantiated on long-term follow-up, in situ saphenous vein bypass may well become recognized as the procedure of choice for lower extremity bypass.

Amputation, Surgical↗
PubMed1977

Serum myocardial enzymes after +Gz acceleration.

Circulating levels of lactate dehydrogenase, glutamate-oxaloacetate, glutamate-pyruvate transaminase, and creatine phosphokinase, as well as its isoenzymes, were measured to investigate the possibility of myocardial damage during acceleration to high +Gz. Serum samples were analyzed in 12 human volunteers before, 6 h after, and 24 h after several bouts of accleration to 6, 8, 9, and 10 G. No substantial elevations of enzyme activities were observed. However, multivariate analysis of variance and multiple comparisons of the data indicated a small but statistically significant (p less than 0.01) increase in creatine phosphokinase. The results were consistent with enhanced skeletal muscle cell permeability consequent to muscular exercise.

Acceleration↗
PubMed1977

Correlates of maximal oxygen consumption during treadmill exercise.

According to the Balke treadmill protocol, 39 healthy male USAF volunteers were subjected to maximal exercise. The subjects as a group passed the anaerobic threshold by the end of exercise since average venous lactate concentrations increased from 11.2 +/- 1.6 mg% (95% confidence limits) to 93.0 +/- 8.5 mg% (95% confidence limits), and the average gas exchange ratio (R) at the end of the exercise was greater than unity (p less than 0.0005). Tests for correlations showed weak but statistically significant (p less than 0.05) relationships between change in venous lactic acid concentrations and R (r = 0.44) and maximal heart rate (r = 0.34). Maximal oxygen consumption was correlated with time of exercise (r = 0.70) and subject weight (r = 0.33). Subject age and initial plasma lactate concentrations were not significantly correlated with any other variables. Multiple linear regression yielded an equation for prediction of maximal oxygen consumption which included terms for time of exercise and subject weight. Although the multiple correlation coefficent (r = 0.75) was statistically significant (p less than 0.05), it was considered insufficient for accurate prediction of maximal oxygen consumption.

Adult↗
PubMed1976

Bradycardia induced by negative acceleration.

Four volunteers were subjected to negative acceleration in a human centrifuge for the purpose of testing a standard lap belt. Three subjects developed a sinus bradycardia. The fourth developed a sinus arrest with a junctional rhythm at -2 G. With return to +1 G, the sinus mechanism recovered with a prolonged P-R interval. Within 2 h, the P-R interval returned to normal. Negative acceleration maneuvers, well within the capabilities of high-performance aircraft, can effect marked changes in the cardiac rhythm. This phenomenon appears to be vagally induced and is remarkably well tolerated.

Acceleration↗
PubMed1976

Intracerebral oxygen and carbon dioxide tensions in the rhesus monkey.

Five rhesus monkeys (M. mulatta) were prepared by surgical placement of a stainless steel implant in the parietal area of the skull. The implant was designed to firmly hold a Teflon coated membrane of a medical mass spectrometer in an intracerebral position. Animals were consecutively exposed to varying ambient oxygen concentrations from 11% to 21%. Intracerebral PO2 and PCO2 and arterial PO2 were all stimultaneously recorded for computer analysis. Results indicate an almost linear relationship between cerebral PO2 and ambient PO2 as well as between cerebral PO2 and arterial PO2. With an ambient oxygen concentration of 21%, the cerebral Po2 and Pco2 were 13.5 +/- 3.5 mm Hg and 50.4 +/- 7.9 mm Hg, respectively. With an ambient oxygen concentration of 10.7%, these values decreased to 2.5 +/- 2.7 mm Hg and 38.0 +/- 5.6 mm Hg.

Animals↗