Search PubMed⌕ Search

Biomedical subjects

C Jewkes

Publications and source records attributed to C Jewkes.

9 recordsLinked to original sources
PubMed2001

Comparative accuracy of cardiovascular risk prediction methods in primary care patients.

OBJECTIVE: To compare the relative accuracy of cardiovascular disease risk prediction methods based on equations derived from the Framingham heart study. DESIGN: Risk factor data were collected prospectively from subjects being evaluated by their primary care physicians for prevention of cardiovascular disease. Projected cardiovascular risks were calculated for each patient with the Framingham equations, and also estimated from the risk tables and charts based on the same equations. SETTING: 12 primary care practices (46 doctors) in Birmingham. PATIENTS: 691 subjects aged 30-70 years. MAIN OUTCOME MEASURES: Sensitivity, specificity, and positive and negative predictive values of the Framingham based risk tables and charts for treatment thresholds based on projected cardiovascular disease or coronary heart disease risk. RESULTS: 59 subjects (8.5%) had projected 10 year coronary heart disease risks >/= 30%, and 291 (42.1%) had risks >/= 15%. At equivalent projected risk levels (10 year coronary heart disease >/= 30% and five year cardiovascular disease >/= 20%), the original Sheffield tables and those from New Zealand have the same sensitivities (40.0%, 95% confidence interval (CI) 26.6% to 57.8% v 41.2%, 95% CI 28.7% to 57. 3%) and specificities (98.6%, 95% CI 97.2% to 99.3% v 99.7%, 95% CI 98.8% to 100%). Modifications to the Sheffield tables improve sensitivity (91.4%, 95% CI 81.3% to 96.9%) but reduce specificity (95.8%, 95% CI 93.9% to 97.3%). The revised joint British recommendations' charts have high specificity (98.7%, 95% CI 97.5% to 99.5%) and good sensitivity (84.7%, 95% CI 71.0% to 93.0%). CONCLUSIONS: The revised joint British recommendations charts appear to have the best combination of sensitivity and specificity for use in primary care patients.

Adult↗
PubMed1999

Prospective, randomized, controlled trial to determine the effect of early enhanced enteral nutrition on clinical outcome in mechanically ventilated patients suffering head injury.

OBJECTIVE: To determine the effect of early enhanced enteral nutrition (EN) on clinical outcome of head-injured patients. DESIGN: Prospective, randomized, controlled trial. SETTING: Tertiary neurosurgical and trauma center. PATIENTS: Eighty-two patients suffering head injury and requiring mechanical ventilation. INTERVENTIONS: Patients were randomized to receive standard EN (gradually increased from 15 mL/hr up to estimated energy and nitrogen requirements) or enhanced EN (started at a feeding rate that met estimated energy and nitrogen requirements) from day 1. Good neurologic outcome (Glasgow Outcome Scale score of 4 or 5) was determined at 3 and 6 months after injury, and the incidence of infective and total complications was determined during the hospital stay up to 6 months. MEASUREMENTS AND MAIN RESULTS: Disease severity assessed by best preintubation Glasgow Coma Scale score, pupillary responses, Injury Severity Score, Acute Physiology and Chronic Health Evaluation II score, computed tomographic scan categorization, and age was similar in both groups. Intervention patients had a higher percentage of energy (p = .0008) and nitrogen (p<.0001) requirements met by EN in the first week after injury. Neurologic outcome at 6 months was similar between groups, but there was a tendency for more intervention patients to have a good neurologic outcome at 3 months than control patients (61% vs. 39%, p = .08). Fewer intervention patients had an infective complication (61% vs. 85%, p = .02) or more than one total complication (37% vs. 61%, p = .046) compared with control patients. Enhanced EN was associated with a reduction in the ratio of serum concentration of C-reactive protein to albumin up to day 6 after injury (p = .004). CONCLUSIONS: Enhanced EN appears to accelerate neurologic recovery and reduces both the incidence of major complications and postinjury inflammatory responses.

Brain Injuries↗
PubMed1995

Hemodynamic effects during induction, laryngoscopy, and intubation with eltanolone (5 beta-pregnanolone) or propofol. A study in ASA I and II patients.

STUDY OBJECTIVE: To evaluate the cardiovascular changes following induction of anesthesia, laryngoscopy, and intubation in patients receiving a bolus dose of either eltanolone or propofol. DESIGN: Randomized, controlled, blind, prospective clinical study. SETTING: General operating theaters of a university hospital. PATIENTS: 40 ASA status I and II patients scheduled for elective surgery. INTERVENTIONS: Patients were premedicated with oral temazepam 20 mg. Anesthesia was induced with either eltanolone 0.58 mg/kg or propofol 1.7 mg/kg, neuromuscular blockade was achieved with vecuronium 0.1 mg/kg, and anesthesia was maintained with enflurane 0.5% to 1.0% in nitrous oxide (67%). MEASUREMENTS AND MAIN RESULTS: Blood pressure was measured using an automatic oscillometric technique, heart rate (HR) was derived from the ECG, oxygen saturation was measured by pulse oximetry, and cardiac output (Q) was measured by a thoracic bioimpedance technique. Induction of anesthesia with either drug, eltanolone or propofol, decreased arterial systolic (SAP) and diastolic (DAP) blood pressure, Q, and stroke volume (SV). HR increased. Systemic vascular resistance (SVR) was unaltered. After laryngoscopy and intubation, SAP and DAP increased secondary to an increase in SVR. HR also increased; SV decreased in patients receiving eltanolone. Side effects (e.g., apnea occurring for more than 30 seconds, involuntary movements, limb hypertonus) occurred at a similar incidence with both treatments, but pain following injection was greater with propofol (59% vs. 9%). CONCLUSIONS: Patients receiving either eltanolone or propofol showed similar cardiovascular changes to induction of anesthesia, although there were greater increases in arterial pressure and HR in those patients receiving eltanolone.

Anesthesia↗
PubMed1994

Does the choice of antihypertensive therapy influence haemodynamic responses to induction, laryngoscopy and intubation?

We have measured haemodynamic responses to induction of anaesthesia, laryngoscopy and intubation in 103 mild-moderate hypertensive patients (83 patients (diastolic pressures < or = 110 mm Hg) currently receiving one of four monotherapies (ACE inhibitors, group A; beta adrenoceptor blocking drugs, group B; calcium channel antagonists, group C; diuretics, group D) and 24 were untreated hypertensive patients). Anaesthesia was induced with fentanyl 1.5-2.0 micrograms kg-1 and thiopentone 3-5 mg kg-1. Tracheal intubation was facilitated by vecuronium 0.1 mg kg-1 and anaesthesia maintained with enflurane and nitrous oxide in oxygen. Systolic and diastolic pressures (SAP, DAP) were measured at 1-min intervals by a non-invasive oscillometric method and cardiac output (CO) and stroke volume (SV) by thoracic bioimpedance. Induction of anaesthesia was associated with a decrease in SAP, DAP and CO in groups A-D (P < 0.05). Heart rate (HR) decreased in groups A and D (P < 0.01) and systemic vascular resistance (SVR) decreased in groups A and B (P < 0.05). SAP and HR increased in all groups after laryngoscopy and intubation (P < 0.01) as did SVR in groups A, B and D (P < 0.02). CO was unaltered. Similar changes occurred in the untreated hypertensive patients, although nine of 24 patients exhibited HR > or = 100 beat min-1 after laryngoscopy and intubation. Comparison of the changes in SAP, DAP, CO and SVR with time showed no differences in the five treatment groups; changes in HR were significantly less in group B compared with the other groups (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗
PubMed1992

Response time of pulse oximeters assessed using acute decompression.

In human volunteers, the response times of 11 pulse oximeters to a 10% step reduction in arterial oxygen saturation were measured using an acute decompression technique. When finger probes were used, nine oximeters had similar response times and two were significantly slower (P less than 0.05). The ear probe response time was similar on six oximeters assessed, and faster than the finger probes. The response times of the oximeters to an acute increase in arterial saturation were tested by suddenly changing the inspired gas from air to 100% oxygen at an ambient pressure of 380 mm Hg. For ear probes, the response times were similar for all oximeters; for finger probes, three fast-responding and three slow-responding oximeters were identified (P less than 0.05). A faster response could be elicited by placing the probes on the thumb (P less than 0.05). We conclude that if a rapid indication of changes in arterial saturation is required, pulse oximeters with ear probes should be used. If finger probes are used, they should be placed on the thumb. The oximeter used will influence the response time if finger probes are used, but it will have little effect if ear probes are used.

Adult↗
PubMed1991

Non-invasive measurement of cardiac output by thoracic electrical bioimpedance: a study of reproducibility and comparison with thermodilution.

The performance and reproducibility of the BoMED NCCOM3 thoracic electrical bioimpedance cardiograph (TEB) has been evaluated in volunteers and patients. In resting supine volunteers, we determined the coefficient of variability over short time periods (30 min) and over several days, and examined the effects of differences in electrode type and electrode placement. The mean (range) intra-subject coefficients of variation (CV) for thoracic fluid index (TFI) and stroke volume (SV) were 1.0% (0.4-1.8%) and 4.7% (2.1-8.5%), respectively over a 30-min period. The corresponding CV were 5.6% (2.3-10.9%) and 10.9% (6.1-14.8%) for measurements made at rest on four separate occasions. Use of different electrode types (RedDot and Medicotest) resulted in differences in TFI (P less than 0.01), but not in mean values for SV or cardiac output (Q); their use in individual subjects revealed differences of up to 20% in SV and Q. Alterations in electrode placement by 5 cm in the horizontal and diagonal planes produced no significant changes in TFI, SV or Q; changes in the longitudinal plane produced a graded change. Increases of 5 cm and 10 cm in thoracic length produced mean increases in TFI of 9.8% and 39.8%, respectively, and mean decreases in Q of 8.4% and 16.7% and SV of 7.5% and 15.8%. TEB measurements of Q and SV were compared with thermodilution (TD) in 16 intensive care patients. Mean (SEM) Q by TEB was 5.63 (1.10) litre min-1 compared with TD 4.38 (0.72) litre min-1 (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗