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Biomedical subjects

C Orchard

Publications and source records attributed to C Orchard.

14 recordsLinked to original sources
PubMed1996

Measuring the effects of casemix on outcomes.

Participation in the measurement of population health and health care outcomes has become an explicit professional duty for doctors, but comparisons are difficult to make because outcomes are conceptually complex and largely qualitative. Observational data, particularly from routine hospital statistics, are useful complements to experimental data provided that their variable quality is taken into account and adjustments are made to minimize bias and confounding and to allow for the effects of differences in casemix, which are problematic because of the nature of severity.

Confounding Factors, Epidemiologic↗
PubMed1994

Comparing healthcare outcomes.

Governments are increasingly concerned to compare the quality and effectiveness of healthcare interventions but find this a complex matter. Crude hospital statistics can be dangerously misleading and need adjusting for case mix, but identifying and weighting the patient characteristics which affect prognosis are problematical for conceptual, methodological, and practical reasons. These include the inherently uncertain nature of prognosis itself and the practical difficulties of collecting and quantifying data on the outcomes of interest for specific healthcare interventions and known risk factors such as severity.

Data Collection↗
PubMed1994

Management of clinical failure in Canadian nursing programs.

There has been growing concern raised by nurse educators regarding the potential for litigation by nursing students who are dissatisfied with educators' appraisal of these students' clinical performance. A descriptive survey using a cross-sectional design was used to assess the relationship between institutional policies and procedures related to student clinical evaluation practices. Population for this survey was diploma and basic baccalaureate nursing programs in Canada (N = 94). The response rate to this survey was 86.2% (81/94 programs). Data were analyzed using descriptive statistics. Reliability of the instrument was assessed using contingency tables comparing the data obtained with the same program's written policies and procedures (p = .50). There were five significant findings: (a) a lack of faculty evaluation standards; (b) clinical instructors evaluating students alone; (c) the same members serving on more than one level of review; (d) lack of procedures when conducting informal and formal hearings; and (e) alteration of professional judgments of nurse faculty by nonnurses.

Canada↗
PubMed1994

The nurse educator and the nursing student: a review of the issue of clinical evaluation procedures.

Research in the area of grievance and appeal mechanisms is very limited. Although writers have addressed aspects of their use, only one study (Orchard, 1991) was carried out to determine what administrative structures and procedures are used to protect both the rights of the instructors and their students in the clinical evaluation process. Further research to both replicate Orchard's study and to analyze specific aspects of nursing programs' existing evaluation and review systems is urgently needed. In the interim, nursing education administrators must rely on this seminal research and/or their personal experiences in the management of failing students. These experiences are augmented by overall institutional policies and reviewed through nursing program accreditation reviews. Although these parameters assist nursing education administrators in determining processes to use when dealing with failing students, they do not guarantee that nursing students or their clinical instructors' rights are protected. Nurse educators need to gain increased knowledge about the legal side of their instructor role (Woodside, 1981). Perhaps once they gain such knowledge, some of the fear frequently experienced by instructors when they are faced with a student threatening to grieve their clinical evaluation will decrease.

Clinical Competence↗
PubMed1992

Factors that interfere with clinical judgments of students' performance.

A review of literature pertaining to clinical evaluation revealed six factors having the potential to interfere unconsciously with the clinical evaluative decision-making process of students' performance. This article provides a synopsis of the writers' views about these factors and provides potential actions to minimize their impact on the decision-making process. Actions are discussed in relation to educational preparation of nurse educators, orientation of new faculty to a program, and faculty practices.

Attitude↗
PubMed1989

The control of calcium influx by cytoplasmic calcium in mammalian heart muscle.

The role of Ca2+ in the initiation and maintenance of contraction has been extensively studies. Many of these studies have focused on how Ca2+ influx and efflux affect cytoplasmic Ca2+ (Cai) and, therefore, contraction in cardiac muscle. However, it has recently become apparent that Cai itself may play a major role in the control of Ca2+ influx and efflux from cardiac muscle. Here we review current ideas on the mechanisms underlying Ca2+ homeostasis in cardiac muscle, with specific attention to how Cai may control Ca2+ influx, both under normal and pathological conditions.

Animals↗
PubMed1989

The effect of acidosis on excitation-contraction coupling in isolated ferret heart muscle.

The contractile response to acidosis is the final product of a number of different changes in the excitation-contraction coupling pathway: (i) Cai increases and subsequently decreases during acidosis; (ii) the action potential becomes longer; (iii) the sensitivity of the contractile proteins to Ca2+ decreases. The increase of Cai and the lengthening of the action potential may help to maintain contractile function, although this advantage may be offset if spontaneous Ca2+ release from the s.r. occurs, secondary to the increase of Cai. The recovery of force shown in figure 1 occurs at a time when the calcium transient is decreasing, and therefore represents an increasing sensitivity of the contractile proteins to Cai, probably due to a recovery of intracellular pH (6), although it is also possible that a disappearance of spontaneous Ca2+ releases from the s.r. may be contributing [2].

Acidosis↗
PubMed1985

Positive end-expiratory pressure may decrease arterial oxygen tension in the presence of a collapsed lung region.

The effect of positive end-expiratory pressure (PEEP) on PaO2 during collapse of a single pulmonary lobe was investigated in seven dogs. Increasing PEEP to the ventilated region of lung increased the proportion of cardiac output flowing to the collapsed lobe and decreased PaO2 and pH. PaCO2 increased at the onset of lobar collapse but was not significantly altered by changes in PEEP. In impaired lungs, the benefits of PEEP may be offset by an increase in blood flow to the unventilated region and hence lead to a decrease in PaO2.

Analysis of Variance↗
PubMed1982

Effect of dantrolene on leg metabolism in porcine malignant hyperthermia.

The effect of the intravenous administration of dantrolene 3.5 mg/kg body weight on leg metabolism during porcine malignant hyperthermia (MH) was investigated in six Pietrain pigs. Arterial pH improved only slowly after dantrolene and was associated with the continuing efflux of lactate from the leg. Oxygen uptake by the leg had returned to control values 30 minutes after dantrolene. Glucose production by the leg was observed during malignant hyperthermia but this was rapidly abolished by dantrolene. It is concluded that the most useful indices for assessing the adequacy of the treatment of MH are those which reflect changes in oxidative muscle metabolism.

Animals↗
PubMed1981

Depression of hypoxic pulmonary vasoconstriction by sodium nitroprusside and nitroglycerine.

The pulmonary vasoconstrictor response to the unilateral administration of 7% oxygen was studied in 10 anaesthetized dogs in which the lungs were mechanically ventilated. The distribution of blood flow between the two lungs was measured continuously by recording the radioactivity in the mixed expired gas from each lung during the infusion i.v. of xenon-133. Infusions of nitroglycerine and sodium nitroprusside which produced the same decrease in mean aortic pressure produced similar decreases in hypoxic pulmonary vasoconstriction. The reduction in arterial PO2 during unilateral hypoxia was greater when the hypoxic vasoconstrictor response was depressed by drugs than it was during the control periods, although mixed venous PO2 was unchanged. It is concluded that both drugs may cause hypoxaemia by increasing the blood flow to alveoli with a low ventilation/perfusion ratio.

Animals↗
PubMed1981

Oxygen tension measurement using an automatic blood gas analyser.

Two different methods of assessing the reliability of the oxygen electrode of one model of an automatic blood gas analyser (BGA) have been studied. In the first, a single automatic BGA was assessed by using outdated bank blood which was pumped around a small extracorporeal circuit into which known gas mixtures were passed. Oxygen tension was varied between 2 and 16 kPa. In the second, fresh heparinized blood was tonometered with calibrated gases and submitted to the automatic BGA used in the first part of the study and also to three other identical machines. Each of the machines was between 3 and 4 years old.Eighteen different units of blood were used in the first part of the study. The correlation coefficient between the automatic BGA and the Po(2) in the extracorporeal circuit varied between 0.29 and 0.99. 31% of the total of 209 measurements made by the automatic BGA were more than 1.2 kPa from the reference value, 25% of them being between 1.2 and 4.0 kPa from the reference value. In the second part of the study, the correlation coefficient between this automatic BGA and the tonometered blood was 0.96. The correlation coefficients for the 3 other identical BGAs were 0.84, 0.97 and 0.88, indicating that the BGA used in the first part of the study was no worse than any of the others.It is suggested that although clinicians are likely to ignore readings of an automatic BGA that are more than 4.0 kPa from the true value and are likely to repeat the investigation, readings between 1.2 and 4.0 kPa from the true value may adversely affect patient management.

Autoanalysis↗
PubMed1979

Depression of hypoxic pulmonary vasoconstriction in the dog by dopamine and isoprenaline.

The effects of dopamine and isoprenaline on the pulmonary vasoconstrictor response to alveolar hypoxia were assessed by measuring the redistribution of blood flow between the lungs in response to unilateral hypoxia. Dose rates of dopamine 25 micrograms kg-1 min-1 and isoprenaline 0.25 micrograms kg-1 min-1 (which produced equal increments in thecontractile force of the heart in dogs) produced a similar degree of depression of they hypoxic vasoconstrictor response, whereas dopamine 2.5 micrograms kg-1 min-1 had little effect on the response PaO2 during unilateral hypoxia was inversely related to the blood flow through the hypoxic lung.

Animals↗
PubMed1979

Effects of heparin and protamine on left ventricular performance in the dog.

The effects of protamine on left ventricular (LV) function were measured under conditions of controlled heart rate and proximal aortic pressure in eight anaesthetized, heparinised dogs. Protamine 3 mg.kg-1 produced a 21% decrease in LV dP/dt max, a 43% decrease in cardiac output, a 47% decrease in stroke work and decreases in systolic and diastolic pressures (-16%, -19% respectively). Protamine 6 mg.kg-1 resulted in a 17% decrease in LV dP/dt max, a 26% decrease in cardiac output, a 50% decrease in LV stroke work and 25 and 30% decreases in systolic and diastolic pressures. These results show that an impairment of LV function plays an important part in the circulatory depression produced by protamine.

Animals↗