Biomedical subjects
J Hooper
Publications and source records attributed to J Hooper.
Evaluation of orally administered highly variable drugs and drug formulations.
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Vulnerability of paediatric myocardium to cardiac surgery.
OBJECTIVE: Myocardial injury is an important cause of mortality and morbidity after paediatric cardiac surgery. Data obtained from studies in animals imply that juvenile myocardium is more resistant to the effects of ischaemia and reperfusion than adult myocardium but there is little confirmatory evidence in the clinical setting. DESIGN: Prospective observational study of biochemical markers of myocardial injury in a paediatric population undergoing cardiac surgery. SETTING: Tertiary referral centre for paediatric cardiac surgery. PATIENTS: Forty patients undergoing paediatric cardiac surgery of varying complexity including closure of atrial and ventricular septal defects and arterial switch for simple transposition. A control group included patients undergoing thoracotomy for closure of a patent ductus arteriosus or repair of a coarctation. INTERVENTIONS: Serial measurements of myoglobin, the MB isoenzyme of creatine kinase (CK-MB), and the highly specific markers of myocardial damage cardiac troponin T (cTnT) and I (cTnI) were made before and 1, 6, 24, and 48 to 72 hours after operation. RESULTS: There were significant increases in myoglobin and CK-MB, but not cTnT or cTnI, in the control group. There were significant increases in the four biochemical markers in all the cardiac operations but especially in the ventricular septal defect and transposition group. Increases in CK-MB and cTnT were about five times greater than those previously reported in adult patients. CONCLUSIONS: (i) Cardiac troponins are more specific markers of myocardial injury in paediatric cardiac surgery than myoglobin and CK-MB. (ii) Paediatric myocardium seems to be more vulnerable to injury during cardiac surgery than adult myocardium.
Some unusual biochemical changes in diabetes mellitus.
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Does activated neutrophil depletion on bypass by leukocyte filtration reduce myocardial damage? A preliminary report.
An important factor in the production of myocardial damage following cardiopulmonary bypass in the creation of oxygen derived free radicals. Few sources for these radicals have been identified but experimentally activated neutrophils are known to release free radical which contribute to myocyte necrosis. The aim of this pilot study was to identify whether, by depleting patients of leukocytes and particularly neutrophils on bypass, a better degree of myocardial protection could be observed using specific identifiers of myocardial damage. Ten patients undergoing urgent coronary artery bypass for unstable angina with impaired left ventricular function were leuko-depleted using a PALL medical leukocyte filter in the extra corporeal circulation together with leukocyte depletion of all transfused blood. A similar group of matched controls had only an arterial line filter without leukodepletion. All patients were operated by one surgeon using identical techniques of intermittent cross clamping and fibrillation at moderate hypothermia. Full blood count, Glutathione, Troponin T and CPK/MB were measured before, during and at identified intervals up to 72 hour after bypass. Preliminary results show little change in the total leukocyte count but the Troponin T and CPK/MB values were lower in the filtered group than in the control group and an increased level of total Glutathione in the filter group showed that there was less oxidated stress on the myocardium. Currently this filter is an expensive addition to bypass surgery but these preliminary results suggest that activated neutrophil depletion on bypass may be of benefit to patients with unstable angina, impending myocardial necrosis and low ejection fraction.
Mental disorders. Targeting the brain.
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Medical education: challenges and opportunities.
New curricula and educational methods are needed in medical education to take account of changes in the material taught, and the way in which education is delivered. We describe two approaches to these challenges--an internationally developed slide-text-based program and a multimedia clinical case-based CD-ROM project.
Hyperchloraemic acidosis during recovery from hyperglycemic diabetic emergencies.
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Tutorial software for clinical chemistry incorporating interactive multimedia clinical cases.
We have developed computer-based clinical case histories incorporating multimedia elements to aid the learning of medicine in a problem-based manner. Topics have been developed in the specialty of Clinical Biochemistry but the approach used is suitable for any branch of clinical medicine. Each topic has material aimed at medical students and also postgraduate candidates for professional examinations. A browser program is also incorporated. Emphasis is made on interaction through the case and modeling of real-life decisions in diagnosis and treatment. Advantages of the program are self-paced learning, assessment of understanding, feedback, and emphasis on deep understanding of the basic physiological and biochemical processes underlying clinical problems.
Three-point restraints as a risk factor for chest injury in the elderly.
As the number of drivers over the age of 65 years increases, new trauma patterns are emerging. The use of lap-shoulder restraints, in this population, is beginning to play an important role in new findings about their injuries. Restraint use in motor vehicle crash victims, in relation to average AIS score, ISS, and number of hospital and ICU days, was studied at a level I trauma center. The control group consisted of 100 patients between the ages of 35 and 45 years, who were involved in motor vehicle impacts (MVIs) from January 1990 through January 1992. The study group consisted of 120 patients over the age of 65 years who were involved in MVIs from January 1987 through January 1992. In the control group, restraint use was associated with a lower average AIS score--3.39 versus 7.35 for the unrestrained victims. In addition, the restrained victims spent fewer days in the ICU--0.08 versus 0.30 days for the unrestrained victims; and fewer hospital days--1.08 versus 2.0 days for the unrestrained victims. The general pattern of lower average AIS scores in restrained victims was also seen in the study group. However, in the study group, lap-shoulder belt-restrained patients had higher average AIS scores, in the chest region, than unrestrained patients--0.92 (SE 1.60) versus 0.71 (SE 1.47), respectively. These findings indicate that physicians must be aware of restraint patterns of chest injury in elderly patients. Aggressive triage criteria and vigorous pulmonary toilet, especially in patients with rib fractures, sternal fractures, and pulmonary contusions, should become integral parts of trauma resuscitation protocols in elderly patients.
Lack of cardioprotective efficacy of allopurinol in coronary artery surgery.
OBJECTIVE: To examine the cardioprotective efficacy of allopurinol in patients undergoing elective coronary artery surgery. DESIGN: Prospective randomised trial. SETTING: London teaching hospital. PATIENTS: Twenty patients with at least moderately good left ventricular function undergoing elective coronary artery surgery and requiring at least two bypass grafts. INTERVENTIONS: Patients were randomised to receive allopurinol (1200 mg in two divided doses) or to act as controls. MAIN OUTCOME MEASURE: The primary determinant of the efficacy of myocardial protection was serial measurement (preoperatively and subsequently at one, six, 24, and 72 hours after the end of cardiopulmonary bypass) of cardiac troponin T (cTnT) a highly sensitive and specific marker of myocardial damage. Additional evidence was provided by serial measurement of the MB-isoenzyme of creatine kinase (CK-MB) and myoglobin, ECG changes, and clinical outcome. RESULTS: There was no significant difference in age, ejection fraction, number of grafts, bypass times, or cross clamp times between the two groups. In both groups there was a highly significant (p < 0.01) rise in cTnT, CK-MB, and myoglobin. Peak concentrations were reached between one (CK-MB and myoglobin) and six hours (cTnT) after the end of cardiopulmonary bypass. At 72 hours cTnT concentrations were six times higher than baseline concentrations whereas CK-MB and myoglobin were approximately double baseline concentrations. There was no significant difference in cTnT, CK-MB, or myoglobin between the allopurinol and control groups at any time. There was no diagnostic ECG evidence of perioperative infarction in any patient. CONCLUSION: Unlike previous reports this study did not show that allopurinol had a cardioprotective effect in patients with good left ventricular function undergoing elective coronary artery surgery.
Immunologically active proteins in intravenous immunoglobulin.
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Characteristics of normal larynges under flexible fiberscopic and stroboscopic examination: an Australian perspective.
The purpose of this study was to investigate the structure and function of larynges of 35 subjects with normal voices. Volunteers aged between 20 and 50 years with no history of voice disorders or laryngeal surgery, no current allergies, no formal voice training, and no hyperactive gag reflex were required to perform various vocal manoeuvres that were carried out under continuous and stroboscopic light. An assessment form was devised to record the condition and function of the larynx. The videotapes of the procedure were rated by experienced judges. The Australian Fiberscopic Profile was devised to record the relevant parameters under continuous light. Videostroboscopic ratings were carried out using the Bless protocol rating. High interjudge agreement was found across the two rating profiles.
Capillary blood glucose measurements in hospital inpatients using portable glucose meters.
BACKGROUND: The use of portable glucose meters by nursing staff to perform bedside capillary blood glucose measurements is standard practice in the management of diabetic hospital inpatients. Few studies, however, have examined the practical limitations or the cost of this technology. AIM: To investigate the performance and cost of capillary blood glucose measurements using portable glucose meters in a hospital inpatient population being managed for diabetes mellitus. METHODS: The setting was a 500 bed metropolitan University Teaching hospital, with 22 meters (Glucometer-M) in routine use by about 450 accredited nursing staff. The Glucometer-M was also compared with an operator-independent meter (Hemocue) to assess the effect of operator bias on the overall efficacy and cost of the programme. RESULTS: Retrospective analysis of Glucometer-M reagent strips and comparison of measurements (n = 72) with the Hemocue revealed a marked operator bias which diminished accuracy and increased costs. The significant proportion of low haematocrits (< 30%) in the hospital population limited the applicability of the Glucometer-M which only operates reliably over the haematocrit range 35-50%. The excess of blood glucose measurements was highlighted by both a hospital ward audit and the frequency which exceeded that of routine electrolyte assays. CONCLUSIONS: Reliable bedside estimation of capillary blood glucose levels in hospitals requires a meter which is accurate, has negligible operator bias, is largely unaffected by haematocrit, and has insignificant risk of cross-contamination. At present only the Hemocue fulfils these specifications. Irrespective of meter choice, it is necessary to develop criteria for glucose measurements and monitor adherence.
Femoral head autografts and contralateral total hip arthroplasty.
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The importance of activity and pretreatment in the prevention of suxamethonium myalgias.
We have studied the effectiveness of pretreatment with atracurium 0.05 mg kg-1 and placebo before administration of suxamethonium, in the prevention of postoperative myalgia in inpatients having surgery in which rapid postoperative mobilization was possible (vaginal hysterectomy). On the second day after operation, the patients pretreated with atracurium had significantly fewer postoperative myalgias than those receiving placebo (P < 0.025). All patients were significantly more active on the second day compared with the first day after operation (P < 0.025). Possible causal relationships are discussed.
Blood lactate and mixed venous-arterial PCO2 gradient as indices of poor peripheral perfusion following cardiopulmonary bypass surgery.
Conventional indices of tissue perfusion after surgery involving cardiopulmonary bypass (CPB) may not accurately reflect disordered cell metabolism. Venous hypercarbia leading to an increased veno-arterial difference in CO2 tensions (V-aCO2 gradient) has been shown to reflect critical reductions in systemic and pulmonary blood flow that occur during cardiorespiratory arrest and septic shock. We therefore measured plasma lactate levels and V-aCO2 gradients in 10 patients (mean age 57.2 years) following CPB and compared them with conventional indices of tissue perfusion. Plasma lactate levels, cardiac index (CI) and oxygen uptake (VO2) all increased significantly (p less than 0.05 vs baseline levels) up to 3 h following surgery. Oxygen delivery (DO2) did not change. Plasma lactate levels correlated significantly with CI (r = 0.47, p less than 0.01). V-aCO2 fell significantly with time (p less than 0.01 vs baseline). There was an inverse relationship between V-aCO2 and cardiac index and V-aCO2 and lactate (r = -0.37, p less than 0.05; r = -0.3, p less than 0.05 respectively). We conclude that blood lactate, CI and VO2 increase progressively following CPB. An increase in lactate was associated with a decrease in V-aCO2. An increase in V-aCO2 was not therefore associated with evidence of inadequate tissue perfusion as indicated by an increased blood lactate concentration.