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Biomedical subjects

M M Mitchell

Publications and source records attributed to M M Mitchell.

At least 19 recordsLinked to original sources
PubMed1990

Measurement of arterial pressure after cardiopulmonary bypass with long radial artery catheters.

Radial arterial pressure can significantly underestimate central aortic pressure in the postcardiopulmonary bypass (post-CPB) period. At the study institution, routine monitoring of perioperative arterial pressure in adult patients undergoing cardiac surgery is performed with a long radial artery catheter with the distal end positioned in the subclavian artery. In 68 patients presenting for elective cardiac surgery, both a conventional short radial artery catheter and a contralateral long radial artery catheter were placed. Analysis of radial and subclavian arterial pressures post-CPB in the first 47 patients showed average maximum differences of 7 mm Hg systolic and 4 mm Hg mean. In 15% of patients, the differences were clinically significant (greater than 20 mm Hg systolic and/or greater than 14 mm Hg mean). In 28 patients, central aortic pressure was measured post-CPB, and subclavian artery pressure was found to be an excellent estimator of central aortic pressure. There were no significant complications related to using long radial artery catheters in the 68 patients who were followed prospectively. Monitoring subclavian arterial pressure by percutaneous insertion of a long radial artery catheter provides a reliable estimation of central aortic pressure, even in patients with significant radial artery-to-central aortic pressure gradients post-CPB.

Adult↗
PubMed1990

Do changes in pulmonary capillary wedge pressure adequately reflect myocardial ischemia during anesthesia? A correlative preoperative hemodynamic, electrocardiographic, and transesophageal echocardiographic study.

Pulmonary capillary wedge pressure (PCWP) is monitored during anesthesia in an attempt to detect changes in myocardial function in patients at risk of preoperative cardiac complications. Because the sensitivity with which preoperative PCWP monitoring indicates myocardial ischemia is uncertain, we monitored PCWP, 12-lead electrocardiogram, and left ventricular wall motion abnormalities as defined by transesophageal echocardiography (TEE) in 98 anesthetized patients before coronary artery bypass grafting. Measurements were made five times in each patient, before and after induction of anesthesia. Myocardial ischemia was identified by TEE in 14 patients; in 10 of these, it was associated with concomitant ST segment depression of at least 1 mm. The onset of ischemia, as defined by TEE, was accompanied by a mean increase in PCWP of 3.5 +/- 4.8 mm Hg, as compared with a mean change of 0 +/- 2.2 mm Hg between observations not associated with the onset of ischemia (p less than 0.01). An increase in PCWP of at least 3 mm Hg, tested as an indicator of ischemia, had a sensitivity of 25% and a positive predictive value of 15%; after correction for background changes associated with anesthetic induction, the sensitivity of this indicator was 33%, and its positive predictive value was 16%. These figures were not improved by selecting cutoff points higher or lower than 3 mm Hg. In this study, the onset of myocardial ischemia was associated with a small yet significant increase in mean PCWP at group level.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗
PubMed1990

Coping strategies used by occupational therapy students during fieldwork: an exploratory study.

This exploratory study examined the coping strategies and perceptions of 24 graduate students in occupational therapy who were participating in their second Level II fieldwork experience. The instruments used were the revised Ways of Coping Checklist (WCCL) (Vitaliano, Russo, Carr, Maiuro, & Becker, 1985) and a questionnaire developed by the authors. The results showed that of the five coping scales of the WCCL, the students used the Problem-Focused and Seeks Social Support strategies more than the Blamed Self, Wishful Thinking, and Avoidance strategies. Most of the students perceived the fieldwork experience as important, controllable, and stressful, but not disruptive to their lives.

Adaptation, Psychological↗
PubMed1989

A comparison of the effects of central v peripheral bolus injections of potassium chloride on aortic root potassium concentrations in swine.

Clinically relevant doses of potassium chloride (equivalent to 2 mEq/60 kg of body weight) were administered as rapid intravenous (IV) boluses to healthy halothane-anesthetized pigs. Potassium was given either peripherally through a standard IV ear catheter or centrally through the central venous port of a pulmonary artery catheter. Multiple injections were made in each pig, and cardiac output was varied by changing end-tidal halothane concentration. The aortic root potassium concentration was measured every three to six seconds for 90 seconds following potassium administration in each pig. Monitored variables included end-tidal halothane, end-tidal carbon dioxide, pulmonary artery pressure, mean arterial blood pressure, cardiac output, electrocardiogram, and temperature. Following both peripheral and central administration of potassium chloride, aortic root potassium increased significantly. However, the time required to achieve the peak aortic root potassium concentration was significantly less after central administration. In addition, the change in aortic root potassium concentration was greater following central administration compared with peripheral. The change in aortic root potassium concentration correlated inversely with cardiac output only after central, but not peripheral injection. Despite marked transient hyperkalemia in all animals, no electrocardiographic evidence of hyperkalemia could be demonstrated. It is concluded that small bolus doses of potassium chloride (2 mEq/60 kg) can be given safely either peripherally or centrally in normal, hemodynamically stable swine.

Animals↗
PubMed1989

Nitrous oxide does not induce myocardial ischemia in patients with ischemic heart disease and poor ventricular function.

Despite evidence from animal experiments to the contrary, nitrous oxide (N2O) reportedly does not induce myocardial ischemia when used as an adjunct to fentanyl anesthesia in patients with coronary artery disease who have well-preserved left ventricular (LV) function. However, the incidence of ischemia with N2O administration in similar patients with poor LV function may be different. The effects of N2O on segmental LV function, as determined by two-dimensional transesophageal echocardiography, changes in the ST-segment of the electrocardiogram were compared with the effects of an equal concentration of nitrogen (N2) (crossover design) in 70 patients who required elective coronary artery bypass grafting. Of these patients, 24% had left ventricular ejection fraction (LVEF) less than or equal to 40%. Myocardial ischemia was diagnosed in 14 patients during the study: four while awake, seven during induction of anesthesia and tracheal intubation, and four during the remainder of the study (one during N2O and three during 100% oxygen; one patient had two distinct periods of ischemia). No value for LVEF could be found that would distinguish between patients who did or did not have ischemia during the study. Patients treated with beta-adrenergic blocking drugs preoperatively were less likely to develop ischemia (P less than 0.05). Preoperative calcium channel blockers made no such differences. Onset of ischemia was not closely associated with hemodynamic changes. Thus, N2O does not induce clinically detectable myocardial ischemia in patients who have coronary artery disease, and poor LV function in situations in which the effects of deepening anesthetic depth and mild depression of global myocardial function are deemed desirable or harmless.

Adult↗
PubMed1988

Professional involvement in sexuality counseling for patients with spinal cord injuries.

A national survey was conducted to determine how occupational therapists and rehabilitation nurses conduct sexuality counseling in practice settings with spinal cord-injured patients. A review of the literature and results from the survey demonstrated a high priority concern for sexuality counseling in the total rehabilitation of the spinal cord-injured patient; however, many of the professionals surveyed did not conduct sexuality counseling as part of their job. This study provides data comparing the sexuality counseling approach taken by these two disciplines and identifies ways to eliminate the incongruities between recommendations made in the literature and actual clinical practice.

Adolescent↗
PubMed1987

Accurate, automated, continuously displayed pulmonary artery pressure measurement.

A computerized signal processing technique that removes low-frequency respiratory variation from pulmonary artery pressure and other central vascular pressure measurements, and produces a waveform devoid of respiratory artifact, has been developed. This technique has been integrated into a portable bedside monitor. The authors tested the technique in critically ill patients, and found that, compared to physician readings of conventional strip charts, it proved to be a very convenient and accurate method of determining pulmonary artery pressures continuously, regardless of ventilation.

Algorithms↗
PubMed1985

Professional development: clinician to academician.

Drawing on literature from other professions, this paper identifies factors that occupational therapists should consider when making the transition from clinician to academician. It describes the following four stages of a professional career: apprentice, colleague, mentor, and sponsor. Five academic stages of faculty development are also presented. In addition, the work life of a faculty member is delineated.

Career Mobility↗
PubMed1979

Intrathoracic electrical impedance measurements from an esophageal probe.

The sensing of intrathoracic electrical impedance from an esophageal probe may allow relatively noninvasive monitoring of cardiac and respiratory functions of particular interest in anesthesia and intensive care. We have obtained a partial solution of the intrathoracic current-field problem for impedance measurements made from a four-terminal linear array of electrodes located in the esophagus. It allows prediction that aortic root motion will exceed aortic distension as a major determinant of the cardiac intrathoracic esophageal impedance signal. This prediction was confirmed for a specific carefully selected and placed electrode array in anesthetized dogs. In general, motions of organs will be more important than volume changes in affecting the esophageal impedance signal. Thus, timing information (preejection period and left ventricular ejection time) is available from electrodes on an esophageal probe, but cardiac output information appears to be inaccessible for fundamental reasons.

Cardiography, Impedance↗
PubMed1979

A model for establishing occupational therapy and physical therapy services in the public schools.

One procedure for the establishment of therapists in public schools and on management and administration teams in the State Department of Public Instruction, Division for Exceptional Children is discussed. A significant aspect of the procedure is a model for a working relationship between the Division for Exceptional Children and the Occupational Therapy and Physical Therapy Divisions in the Department of Medical Allied Health Professions in a School of Medicine.

Child↗
PubMed1978

Conservation of illusion-distorted identity tasks.

Four conservation of illusion-distorted identity tasks were presented to 10 boys ranging in chronological age (CA) from 5-5 to 12, and in mental age (MA) from 3-5 to 10-2, to document individual differences among children with delayed development in acquisition of conservation skills.

Child↗