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J Hooper

Publications and source records attributed to J Hooper.

At least 55 records · Page 3Linked to original sources
PubMed1998

Log-jam in acid-base education and investigation: why make it so difficult?

Medical students frequently have difficulty in interpreting acid-base data particularly when pH values are used. The difficulty persists when students qualify and has implications for the safe management of patients who require investigation of acid-base status. Simplification of tuition is required together with a change of practice in the reporting of acid-base data by the laboratories. To improve understanding, we recommend that the teaching and reporting of acid-base status should be changed to use [H+] instead of pH, and a greater emphasis placed on the logical interpretation of primary measurements--that is [H+] and PCO2--with less reliance on derived variables.

Acid-Base Equilibrium↗
PubMed1998

Can C reactive protein or troponins T and I predict outcome in patients with intractable unstable angina?

OBJECTIVE: To determine whether a single blood test for the measurement of C reactive protein, or troponin I or T concentrations could be used to stratify patients with intractable unstable angina awaiting transfer for coronary angiography by correlating these values with coronary anatomy and transient myocardial ischaemia. DESIGN: Prospective study. SETTING: Tertiary cardiac unit. PATIENTS: All patients admitted to their local hospital with ischaemic chest pain, uncontrolled by medical treatment, in whom acute myocardial infarction had been excluded by serial measurement of creatine kinase and lack of Q waves on ECG. INTERVENTION: Coronary angiography and ST segment monitoring for 24 hours. MAIN OUTCOME MEASURES: Concentrations of C reactive protein, troponins T and I, coronary anatomy, presence of transient myocardial ischaemia. RESULTS: Median C reactive protein, troponin I, and troponin T concentrations were 17.1 mg/dl (4.8 to 203.9), 0.05 microgram/l (0 to 7.8), and 0.0 microgram/l (0 to 2.51), respectively. Seven patients (10%) had normal coronaries and 14, 20, and 31 had one, two, or three vessel coronary disease, respectively. Nineteen (26%) had transient myocardial ischaemia, 33 (46%) had complex lesion morphology, and six (8%) had intracoronary thrombus. Of the three markers, troponin T alone was higher in patients with multivessel disease (p < 0.05) and in those with transient myocardial ischaemia (p < 0.05), but there was no significant relation between C reactive protein, troponin T or I and lesion morphology or thrombus. CONCLUSIONS: In patients transferred to a tertiary centre with intractable chest pain, C reactive protein and troponin I are not predictive of transient myocardial ischaemia or lesion morphology, both of which are surrogate markers of outcome. Troponin T is, however, raised in patients with multivessel disease or transient myocardial ischaemia. These serum protein assays cannot be used to stratify the risk of patients with unstable angina who are awaiting transfer to the tertiary centre.

Adult↗
PubMed1997

Effects of age and ischemic times on biochemical evidence of myocardial injury after pediatric cardiac operations.

INTRODUCTION: The vulnerability of pediatric myocardium to ischemia is poorly documented in the clinical setting. METHODS: Serial measurements of serum concentrations of myoglobin, the MB isoenzyme of creatine kinase, and cardiac troponins T and I and their respective areas under the curve were obtained, with particular reference to age and ischemic time, in 80 children undergoing cardiac operations. Sixteen (the control group) did not require cardiopulmonary bypass and 64 did. RESULTS: In the control group there were increases (p < 0.01) in myoglobin and creatine kinase MB isoenzyme but no increase in cardiac troponin T or I; by contrast, the group treated with cardiopulmonary bypass had significant increases in all four markers but with differing temporal patterns. Younger age (especially < 12 months) was a highly significant explanatory variable only for the release of cardiac troponins T and I, and ischemic time was a significant explanatory variable for the release of creatine kinase MB isoenzyme, cardiac troponins T and I, but not myoglobin. In comparison with previous studies in adults, creatine kinase MB and cardiac troponin T concentrations were three times greater in children than in adults. CONCLUSIONS: This study supports the specificity of cardiac troponins T and I as markers of myocardial injury after pediatric cardiac operations and defines the importance of age and ischemic time in determining their release. In comparison with previous data in adults, our results raise the possibility that the pediatric heart may be more vulnerable to the effects of ischemia and reperfusion. Cardiac troponins will permit comparison of new myocardial protective strategies or other potentially therapeutic myocardial interventions.

Adult↗
PubMed1997

Ischaemic preconditioning reduces troponin T release in patients undergoing coronary artery bypass surgery.

OBJECTIVE: To investigate whether ischaemic preconditioning could reduce myocardial injury, as manifest by troponin T release, in patients undergoing elective coronary artery bypass surgery. DESIGN: Randomised controlled trial. SETTING: Cardiothoracic unit of a tertiary care centre. PATIENTS: Patients with three vessel coronary artery disease and stable angina admitted for first time elective coronary artery bypass surgery were invited to take part in the study; 33 patients were randomised into control or preconditioning groups. INTERVENTION: Patients in the preconditioning group were exposed to two additional three minute periods of myocardial ischaemia at the beginning of the revascularisation operation, before the ischaemic period used for the first coronary artery bypass graft distal anastomosis. MAIN OUTCOME MEASURE: Serum troponin T concentration at 72 hours after cardiopulmonary bypass. RESULTS: The troponin T assays were performed by blinded observers at a different hospital. All patients had undetectable serum troponin T (< 0.1 microgram/l) before cardiopulmonary bypass, and troponin T was raised postoperatively in all patients. At 72 hours, serum troponin T was lower (P = 0.05) in the preconditioned group (median 0.3 microgram/l) than in the control group (median 1.4 micrograms/l). CONCLUSIONS: The direct application of a preconditioning stimulus in clinical practice has been shown, for the first time, to protect patients against irreversible myocyte injury.

Adenosine Triphosphate↗
PubMed1997

Plasma brain natriuretic peptide concentrations in patients with chronic mitral regurgitation.

BACKGROUND AND AIMS OF THE STUDY: Patients with chronic mitral regurgitation (MR) are often referred for surgery only after irreversible left ventricular (LV) dysfunction has developed. Our aim was to determine whether plasma brain natriuretic peptide (BNP) concentrations could serve as a marker for early LV dysfunction in this condition. METHODS: Twenty-two patients with isolated chronic MR and echocardiographic evidence of at least moderate regurgitation were studied. RESULTS: Plasma BNP concentrations were significantly higher in patients than in normal volunteers (20.85 +/- 16.9 versus 3.37 +/- 0.9 pmol/l; p = 0.007). Concentrations increased with increasing severity of symptoms and were highest in those in NYHA class IV, but did not correlate with LV dimensions, fractional shortening or left atrial size. Of note, two asymptomatic patients with high BNP concentrations were referred for surgery within the 12-month follow up period due to symptom progression. CONCLUSIONS: Plasma BNP concentrations are elevated in most patients with isolated chronic MR, including those who are asymptomatic with normal LV dimensions. The significance of these findings is uncertain, but they suggest that changes in ventricular physiology occur early in the disease process and before they can be detected echocardiographically. Longitudinal studies are required to determine if patients with high BNP levels have an adverse prognosis and if this can be altered by earlier surgical intervention.

Adult↗
PubMed1996

Leg blood flow, metabolism and exercise capacity in chronic stable heart failure.

OBJECTIVES: To assess the metabolic state of skeletal muscle during exercise in patients with chronic heart failure (CHF) and relate this to exercise capacity. BACKGROUND: During exercise in CHF, there is little relation between exercise capacity and central haemodynamic function. Skeletal muscle and limb blood flow are abnormal in CHF. We investigated the relationship between leg blood flow, metabolism and exercise capacity and ventilation in 10 patients (average age 63.3 +/- 6.0 years; 3 female) with stable CHF. METHODS: Patients undertook maximal exercise testing. Peak oxygen consumption (VO2) and the slope of the relationship between ventilation and carbon dioxide production (VE/CO2 slope) were derived. During a supine cycle exercise test, cardiac output (CO) by Doppler echocardiography, femoral blood flow (FBF) by thermodilution, pulse and blood pressure were recorded, and radial arterial and femoral venous blood samples taken for catecholamine, lactate and potassium estimation every 3 min. RESULTS: The average peak VO2 was 19.7 (+/- 5.2; range 11.3-29.0) ml/kg/min. The proportion of CO to the right leg increased from 0.08 (+/- 0.03) to 0.22 (+/- 0.06) (P < 0.001) at 3 min, with no further significant change thereafter. There was a liner increase in leg VO2 reaching a plateau towards peak. At peak, femoral venous saturation was 22.79% +/- 7.20%. Venous lactate and potassium were higher than arterial (P < 0.001 for each comparison). There was no correlation between exercise performance and any of the measured metabolites either in absolute measurements, expressed as change from rest to peak exercise or as arterio-venous difference. The closest correlate of leg VO2 was leg hydrogen ion production, V[H+]. Change in femoral venous lactate from rest to peak exercise correlated with VE/VCO2 slope even when calculated from before the anaerobic threshold (r = -0.80; P = 0.025). CONCLUSIONS: In CHF, exercise capacity is not determined by individual haemodynamic events, and does not seem to be determined by the possible humoral signals we investigated. Ventilation is abnormal before anaerobic threshold, and predicts subsequent lactate rise, suggesting that skeletal muscle is the origin of excessive ventilation.

Aged↗
PubMed1996

Effects of short-term supplementation with coenzyme Q10 on myocardial protection during cardiac operations.

BACKGROUND: Coenzyme Q10 (CoQ10) is a naturally occurring vitamin-like substance that may have a beneficial role in ischemia-reperfusion injury. Coenzyme Q10 administered either as an additive to cardioplegia or as long-term preoperative oral supplementation has been reported to ameliorate myocardial injury after cardiac operations. METHODS: To determine whether short-term supplementation with large doses of CoQ10 (600 mg in divided doses 12 hours before operation) was effective in myocardial protection, 20 patients with well-preserved left ventricular function (ejection fraction greater than 0.50) undergoing elective coronary revascularization were enrolled in a prospective, double-blind, placebo-controlled randomized trial. Serial concentrations of CoQ10, myoglobin, creatine kinase MD fraction, and cardiac troponin T were measured preoperatively and 1, 6, 24, 72, and 120 hours postoperatively. Efficacy of myocardial protection was also assessed by clinical outcome and serial changes in electrocardiographic indices. RESULTS: The patient groups were similar with respect to preoperative and intraoperative characteristics. There was no significant difference in the preoperative plasma levels of CoQ10. These levels fell significantly in both groups after operation, although the magnitude of the decrease was less in the CoQ10-supplemented group (43% versus 60%). In both groups, there were significant postoperative increases in myoglobin, creatine kinase MB fraction, and cardiac troponin T. The magnitude of increases in cardiac troponin T was greater in the CoQ10-supplemented group, reaching marginal overall statistical significance (p = 0.06). CONCLUSIONS: Short-term supplementation with large doses of CoQ10 does not lead to improved myocardial protection in patients undergoing coronary revascularization with well-preserved ventricular function and relatively short ischemic times.

Coenzymes↗
PubMed1996

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.

Adult↗
PubMed1996

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.

Aged↗
PubMed1996

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.

CD-ROM↗
PubMed1996

Staff rights.

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Humans↗