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F G Shellock

Publications and source records attributed to F G Shellock.

At least 127 records · Page 7Linked to original sources
PubMed1985

Muscle and femoral vein temperatures during short-term maximal exercise in heart failure.

Core temperature decreases throughout short-term maximal exercise in heart-failure patients. To investigate possible causes for this unusual response to exercise, we studied core (pulmonary arterial blood), femoral vein, muscle, and skin temperatures in eight patients with severe heart failure who performed maximal upright incremental bicycle exercise to 50 W. A normal group (n = 4) was exercised for comparison. In the heart-failure patients, core temperature was 36.95 +/- 0.37 degrees C at rest, significantly (P less than 0.05) decreased at 25 W of exercise to 36.59 +/- 0.40 degrees C, and at 50 W remained decreased to 36.57 +/- 0.40 degrees C. In comparison, we found that the resting core temperature in the normal subjects was 37.28 +/- 0.34 degrees C, was the same at 25 W (37.29 +/- 0.41 degrees C), and increased significantly (P less than 0.05) to 37.50 +/- 0.32 degrees C at 50 W of exercise. Femoral vein temperature in heart-failure patients (n = 6) was below core temperature throughout exercise to 25 and 50 W (36.22 +/- 0.62 and 36.34 +/- 0.65 degrees C, respectively). Muscle temperature (n = 7) was significantly (P less than 0.05) lower in the heart-failure patients (34.8 +/- 1.1 degrees C) at rest compared with the normal subjects (36.2 +/- 1.0 degrees C). During exercise, muscle temperature increased above core temperature in only four of the heart-failure patients and was significantly (P less than 0.05) lower (36.5 +/- 1.3 degrees C) compared with the normal subjects (38.0 +/- 0.2 degrees C).(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1985

Early central venous pressure changes in the rat during two different levels of head-down suspension.

The head-down suspension (i.e. antiorthostatic hypokinesia) rat is used to simulate the circulatory effects of weightlessness. However, little is known about the early cardiovascular adaptive response to simulated weightlessness and the effects of varying degrees of head-down suspension. Therefore, the purpose of this study was to characterize the early central venous pressure changes to two different levels of head-down suspension in the rat. Unanesthetized, unrestrained, female Sprague-Dawley rats (wt: 298 +/- 18 gms, mean +/- S.D.) with chronically implanted central venous pressure catheters were subjected to either a 45 degrees C head-down tilt angle (Group A, N = 8) or a 20 degrees head-down tilt angle (Group B, N = 8) using the tail-traction technique of head-down suspension. Central venous pressure increased significantly (p less than 0.05) in both groups of rats during head-down suspension with the absolute pressure level significantly (p less than 0.05) higher in Group A rats compared to Group B rats during the first 8 h of the study. At 24 h, the rats in Group B appeared to adapt earlier to head-down suspension because central venous pressure decreased to the previous baseline level whereas it remained increased in Group A rats. We conclude that the level of head-down suspension significantly affects the early central venous pressure response and subsequent cardiovascular adaption to simulated weightlessness in rats.

Animals↗
PubMed1984

Myocardial metabolic and hemodynamic effects of intravenous MDL-17,043, a new cardiotonic drug, in patients with chronic severe heart failure.

MDL-17,043, a new inotropic drug with vasodilator properties, has been shown to produce salutary hemodynamic effects in severe heart failure, but its effects on myocardial metabolism are unknown. To determine whether such hemodynamic effects are associated with adverse effects on the myocardial oxygen demand and supply relationship, we evaluated the effects of intravenous MDL-17,043 given in incremental doses to a mean maximum dose of 2.1 mg/kg, in nine patients with severe chronic heart failure. Overall cardiac pump performance was significantly improved by MDL-17,043, as reflected by an 88% increase in stroke work index (17 +/- 11 to 32 +/- 19 gm-m/m2; p less than 0.001), a 43% reduction in left ventricular filling pressure (28 +/- 4 to 16 +/- 5 mm Hg; p less than 0.0001), a 49% reduction in systemic vascular resistance (1832 +/- 490 to 937 +/- 296 dynes-sec-cm-5; p less than 0.0001) with a slight (11%) decrease in mean arterial pressure (86 +/- 17 to 76 +/- 19 mm Hg; p = 0.005) and without significant changes in heart rate (88 +/- 14 to 91 +/- 12 bpm; p = NS). These hemodynamic effects were associated with an 18% reduction in myocardial oxygen consumption (17 +/- 5 to 14 +/- 5 ml/min p = 0.01), a 17% reduction in myocardial arteriovenous oxygen difference (13.2 +/- 2.4 to 10.9 +/- 1.8 volumes %; p = 0.01), and a 120% improvement in external myocardial efficiency (stroke work index/oxygen consumption) (1.0 +/- 0.6 to 2.2 +/- 0.9; p less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1984

Temperature regulation during treadmill exercise in the rat.

The response of colonic and tail-skin temperatures to treadmill exercise was assessed in female Sprague-Dawley rats using incremental and single-stage exercise protocols to investigate the relationship between deep body temperature and work rate. O2 uptake (VO2) was measured by flow-through technique to evaluate the exercise intensity. Experiments were performed in ambient temperatures below (22-25 degrees C) and above (33-35 degrees C) the thermoneutral zone of the rat. During graded incremental exercise there was a linear relationship between colonic temperature (Tco) and VO2 in both the cooler and warmer ambient temperatures. However, Tco and tail-skin temperature (Tsk) at comparable work rates in the cooler and warmer environments were 40.22 +/- 0.59, 34.84 +/- 1.10 degrees C and 42.04 +/- 0.57, 38.39 +/- 1.54 degrees C, indicating that the rise in Tco was unrelated to the severity of exercise. During single-stage exercise the rats were able to achieve thermal equilibrium but only at low work rates and in the cool environment (22-25 degrees C). There were no significant differences in Tco at the first three levels of single-stage exercise (stage 1, 39.63 +/- 0.34 degrees C; stage 2, 39.67 +/- 0.49 degrees C; stage 3, 39.75 +/- 0.50 degrees C) despite significant differences in VO2 (stage 1, 4.3 +/- 0.7 ml X min-1 X 100 g-1; stage 2, 5.3 +/- 0.6 ml X min X 100 g-1; stage 3, 7.6 +/- 1.2 ml X min-1 X 100 g-1). This demonstrates that there was no relationship between the level of Tco maintained during exercise and the work intensity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Thermodilution cardiac output determination in hypothermic postcardiac surgery patients: room vs ice temperature injectate.

In normothermic patients, room temperature and ice temperature injectate have been shown to result in comparable thermodilution cardiac output measurements. However, room temperature injectate may give inaccurate results in hypothermic patients, particularly if the injectate volume is small, because of the lower injectate-to-blood temperature differential. We compared determinations of cardiac output using 10- and 5-ml volumes of room temperature (19-25 degrees C) injectate to those using 10-ml volumes of ice temperature (0-5 degrees C) injectate in 26 hypothermic (32.7 +/- 1.2 degrees C) postcardiac surgery patients. The cardiac outputs ranged from 1.8 to 5.3 L/min. Regression analysis demonstrated a close relationship between the cardiac outputs measured using room temperature injectate compared to those using ice temperature injectate (0.951 for the 10-ml volumes, 0.925 for the 5-ml volumes). We conclude that the room temperature injectate method is acceptable for determining thermodilution cardiac outputs in moderately hypothermic patients.

Adult↗
PubMed1982

Simplified and highly accurate core temperature measurements.

A commercially available, highly accurate (+/- 0.01 degree C) thermistor catheter is described along with the feasibility of using this device to measure pulmonary artery blood temperature (core temperature) in appropriate thermoregulation studies. Intracardiac pressure monitoring, thermodilution cardiac output, and mixed venous blood sampling may also be performed with this catheter. In addition, other clinical situations which require temperature measurement such as diagnosis of malignant hyperthermia and monitoring patients after hypothermic cardiopulmonary bypass surgery may benefit from the use of this thermistor catheter.

Body Temperature↗
PubMed1980

Sustained beneficial effects of oral pentaerythritol tetranitrate on ventricular function in chronic congestive heart failure.

The hemodynamic effects of a single oral dose of 80 mg of pentaerythritol tetranitrate (PETN) were determined in 16 patients with chronic congestive heart failure over a 5-hour period. PETN produced significant (p < 0.05) decreases in pulmonary capillary wedge pressure (27 to 18 mmHg), right atrial pressure (15 to 9 mmHg), mean systemic arterial pressure (89 to 80 mmHg) and systemic vascular resistance (1812 to 1466 dynes . sec . cm-5). There were significant increases (p < 0.01) in cardiac index (2.0 to 2.3 l/m2/min) stroke volume index (24 to 38 ml/m2) and stroke work index (25 to 31 gm-m/m2). The peak reduction in pulmonary capillary wedge pressure occured two hours after PETN administration and the hemodynamic effects were still apparent at fivae hours following drug ingestion. In nine patients in whom left and right ventricular ejection fractions were determined by radionuclide ventriculography before and after administration of PETN, no significant changes were found in left ventricular ejection fraction (0.22 to 0.24, p. = NS) although a modest increase was noted in right ventricular ejection fraction (0.29 to 0.34 p < 0.05). The data indicates that orally-administered pentaerythritol tetranitrate may produce beneficial effects on preload and afterload in congestive cardiac failure, the duration of which may be five hours or longer.

Administration, Oral↗
PubMed1980

Sustained benefits or oral pentaerythritol tetranitrate on ventricular function in chronic congestive heart failure.

The hemodynamic effects of a single oral dose of 80 mg of pentaerythritol tetranitrate (PETN) were determined over a 5-hr period in 16 patients with chronic congestive heart failure. PETN decreased (p < 0.05) pulmonary capillary wedge pressure (27 to 18 mm Hb), right atrial pressure (15 to 9 mm Hg), mean systemic arterial pressure (89 to 80 mm Hg), and systemic vascular resistance (1,812 to 1,466 dynes x sec x cm-5). There were increases (p < 0.01) in cardiac index (2.0 to 2.3 l/m2/min), stroke volume index (24 to 28 ml/m2), and stroke work index (25 to 31 gm-m/m2). Peak reduction in pulmonary capillary wedge pressure occurred 2 hr after PETN and hemodynamic effects were still apparent at 5 hr. In nine patients in whom left and right ventricular ejection fractions were determined by radionuclide ventriculography before and after PETN, no changes were found in left ventricular ejection fraction (0.20 to 0.22, p = NS) although there was a modest increase in right ventricular ejection fraction (0.29 to 0.34, p < 0.05). The data indicate that oral PTEN may induce beneficial effects on preload and afterload in congestive cardiac failure that may last 5 or more hours.

Administration, Oral↗
PubMedDate not supplied

Policies, guidelines, and recommendations for MR imaging safety and patient management. SMRI Safety Committee.

The following are policies, guidelines, and recommendations from the Safety Committee of the Society for Magnetic Resonance Imaging (SMRI) concerning various issues related to magnetic resonance (MR) imaging safety and patient management. These policies, guidelines, and recommendations were developed to provide standardized and consistent information for use by health practitioners involved in clinical MR imaging.

Humans↗
PubMedDate not supplied

Extrusion of eye socket magnetic implant after MR imaging: potential hazard to patient with eye prosthesis.

Metallic implants or prostheses can be potentially hazardous during magnetic resonance (MR) imaging because of movement or dislodgment of the foreign object. Magnetic eye implants have been reported to exhibit strong movement when placed in water and exposed to a field of 1.5 T. The authors report a case of orbital implant extrusion possibly caused by the movement of a magnetic orbital implant during MR imaging at 0.5 T.

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