Biomedical subjects

M J Brooks

Publications and source records attributed to M J Brooks.

13 recordsLinked to original sources

PubMed2006

Assessing the impact of renal impairment on outcome after arterial intervention: a prospective review of 1,559 patients.

AIM: To investigate the impact of pre and peri-operative renal impairment on outcome, and the need for renal replacement therapy, in a multicenter study of patients undergoing a variety of surgical and radiological arterial procedures. METHODS: A six month prospective multi-centre study of 1,559 consecutive patients undergoing arterial interventions was performed. The primary outcome measures were the development of renal impairment, 30 day mortality and the need for renal replacement therapy. CRI was defined as an admission serum Creatinine>125 micromol/l. ARI was defined as a rise in serum Creatinine of >50% above pre-operative levels, excluding patients in whom the post operative level remained <125 micromol/l. A multivariate logistic regression model was constructed to identify independent risk factors for the development of ARI and mortality. RESULTS: There was a significantly increased 30 day mortality in those patients who developed ARI (29/90 - 32%) or who had CRI (43/269 - 16%) when compared with those whose creatinine remained normal throughout (44/1200 - 4%) (p<0.0001 - Chi-square test). One thousand two hundred and ninety patients had normal pre operative renal function and 269 patients had CRI. Seven percent (90/1290) of the patients with normal pre-operative creatinine developed ARI. Operation type, emergency presentation, and chronic renal impairment were independent predictors of both acute renal impairment (p<0.01) and mortality (p<0.001). Sixteen patients (1%) required temporary haemofiltration (in 9 patients this developed in the context of multiple organ failure) with only 1 requiring long term support. Eleven of these patients died (30 day mortality 69%). CONCLUSIONS: Renal failure following arterial intervention is associated with significant mortality. Renal replacement therapy is necessary mainly in the setting of multiple organ failure on intensive care units with few patients surviving to require long term renal replacement therapy. The identification of the 'at risk' patient is most strongly associated with age, raised preoperative creatinine, emergency procedures and thoraco-abdominal aneurysm.

Acute Kidney Injury↗

PubMed2005

Comparison of Surgical Risk Score, POSSUM and p-POSSUM in higher-risk surgical patients.

BACKGROUND: Much current interest is focused on the use of the Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity (POSSUM) and the Portsmouth predictor equation (p-POSSUM) for risk-adjusted surgical audit. The Surgical Risk Score (SRS) has been shown to offer an equivalent accuracy, but was validated using a cohort that contained a high proportion of low-risk patients. The aim of this study was to compare the accuracy of mortality prediction using SRS with that of POSSUM and p-POSSUM in a cohort of higher-risk patients. METHODS: Some 949 consecutive patients undergoing inpatient surgical procedures in a district general hospital under the care of a single surgeon were analysed. RESULTS: The observed 30-day mortality rate was 8.4 per cent. Mean mortality rates predicted using SRS, POSSUM and p-POSSUM scores were 5.9, 12.6 and 7.3 per cent respectively. No significant difference was observed in the area under the receiver-operator characteristic curves for the three methods. CONCLUSION: The SRS accurately predicted mortality in higher-risk surgical patients. The accuracy of prediction equalled that of POSSUM and p-POSSUM.

Hospital Mortality↗

PubMed2001

Cardiac investigation and intervention prior to thoraco-abdominal aneurysm repair: coronary angiography in 35 patients.

OBJECTIVE: retrospective studies indicate a high risk of cardiac events in patients undergoing thoraco-abdominal aneurysm repair. We aimed to determine the prevalence of coronary disease in these patients, define the role of non-invasive cardiac testing and assess the short-term outcome of coronary re-vascularisation. DESIGN: a prospective cohort study of consecutive patients referred to a single surgeon. MATERIALS AND METHODS: forty patients recruited over 16 months (Type I, 6; II, 11; III, 8; IV, 15). Dobutamine stress echocardiography, coronary angiography and coronary re-vascularisation (PTCA or CABG) were performed according to a pragmatic protocol. Main outcome measures were the prevalence of coronary artery disease, sensitivity and specificity of clinical assessment and non-invasive cardiac testing, and adverse events associated with coronary investigation and intervention. RESULTS: seven patients (17.5%) were stratified as having high perioperative cardiac risk. The majority of patients (23, 57.5%) had no cardiac risk factor other than the operation type. Five patients (12.5%) had inducible ischaemia on non-invasive testing. Fourteen patients (40%) had haemodynamically significant coronary artery stenoses, of whom 12 (34%) underwent coronary revascularisation. Dobutamine stress echocardiography demonstrated 100% specificity and 71% sensitivity for the detection of significant coronary artery lesions. Coronary re-vascularisation by three-vessel bypass grafting was complicated by non-fatal stroke in one patient. Thirty-five patients (87.5%) proceeded to aneurysm repair. No patient who had been adequately investigated suffered a cardiac complication. CONCLUSIONS: the 40% prevalence of coronary artery disease in these patients is comparable to that of other patients undergoing arterial surgery. Non-invasive testing proved beneficial, both in screening low-risk patients and planning intervention in patients at higher risk. An aggressive approach to intervention was associated with an acceptable complication rate and favourable short-term outcome.

Adult↗

PubMed2001

Immunogenic and isotype-specific responses to Russian and US cold-adapted influenza a vaccine donor strains A/Leningrad/134/17/57, A/Leningrad/134/47/57, and A/Ann Arbor/6/60 (H2N2) in mice.

The immunogenicity of the Russian cold-adapted (ca) donor stains, A/Leningrad (Len)/134/17/57 and A/Leningrad/134/47/57, and the US strain A/Ann Arbor (AA)/6/60-ca, were compared in BALB/c mice with their respective wild-type parental viruses. Each ca donor strain was less immunogenic than its wild-type parent. The vaccinating dose, when administered twice, which prevented multiplication of a standard challenge of parental wild-type virus in 50% of mice (the 50% protective dose or PD(50)), was shown for A/Len/134/17/57-ca, A/Len/134/47/57-ca, and A/AA/6/60-ca to be 10(3.77), 10(4.32), and 10(4.70), respectively. These findings were extended by measuring the number of antibody secreting cells induced in the lungs and mediastinal lymph nodes of mice infected with the same ca donors using an ELISPOT assay. When each donor strain was administered twice at a dose of 100 PD(50) over a 3-week interval, the overall immunoglobulin isotype antibody secreting cell profiles were shown to be similar. However, A/Len/134/17/57-ca and A/Len/134/47/57-ca induced significantly higher total immunoglobulin responses in the lungs than A/AA/6/60-ca (P < 0.05). A/Len/134/17/57-ca also induced a significantly greater IgA response in the lungs than A/AA/6/60-ca (P < 0.05). These results suggest that A/Len/134/17/57-ca is a superior immunogen to A/Len/134/47/57-ca which in turn is more immunogenic than A/AA/6/60-ca.

Adaptation, Physiological↗

PubMed1999

Elective repair of type IV thoraco-abdominal aortic aneurysms; experience of a subcostal (transabdominal) approach.

OBJECTIVE: preoperative pulmonary function has been shown by univariate analysis to be an independent predictor of outcome following Crawford Type IV thoraco-abdominal aortic aneurysm repair. The aim of this study was to determine if outcome had been improved by the introduction of a subcostal approach for the elective repair of these aneurysms. METHODS: 39 patients studied (19 subcostal, 20 thoracolaparotomy) all operated on between 1993 and 1998 by a single surgeon using a standard technique. No significant difference in median age (69 years) or weight (64 kg vs. 69 kg) between the two groups. RESULTS: preoperative co-morbidities, pulmonary function and predictors of respiratory failure did not vary significantly between the two groups, despite a trend towards greater respiratory, cardiac and renal disease in the subcostal group. Preoperative median pulmonary function in both groups was 80% of that predicted for age, sex and height. The subcostal approach did not significantly reduce blood loss (3500 ml vs. 4500 ml) or anaesthetic time (255 min vs. 253 min). Overall 30 day mortality was 10.2%. The rate of re-operation was significantly higher in the subcostal group (21% vs. 0%, p=0.05). No differences were observed in intensive care unit stay, total hospital stay or respiratory complications, despite earlier extubation of the subcostal group (47% vs. 10% extubated at 12 h, p=0.01). CONCLUSION: the introduction of a subcostal approach for type IV thoraco-abdominal aneurysm repair in selected "high risk" patients has been associated with an unacceptably high rate of complications requiring early re-operation. We feel that this relates to the problems inherent in the introduction of a new technique and reduced exposure in patients of inappropriate body habitus. The predicted benefit to pulmonary function is realised in shorter intubation times, but has not translated into earlier recovery or improved outcome. Operation duration and blood loss have not been significantly reduced. Based on these outcomes, we do not currently recommend the general adoption of this approach in all type IV repairs. We will continue to evaluate this approach in patients with poor pulmonary function and a suitable body habitus.

Aged↗

PubMed1997

Biphasic waveforms for ventricular defibrillation: optimization of total pulse and second phase durations.

Waveform parameters may affect the efficacy of ventricular defibrillation. Certain biphasic pulse waveforms are more effective for ventricular defibrillation than monophasic waveforms, but the optimal biphasic waveform parameters have not been identified. The purpose of this study was to investigate the effects of total pulse duration and the duration of the second (negative) phase on voltage and energy defibrillation requirements using biphasic waveforms. Defibrillation efficacy was evaluated in an isolated rabbit heart model using the Langendorff technique. The biphasic waveform was a truncated exponential with the initial voltage of the second phase equal to 50% of the final voltage of the first phase. An up/down protocol was used to determine the 50% probability-of-success levels (E50) for delivered energy and initial voltage. First, using pulse waveforms with equal positive and negative phase durations, test waveforms with total durations of 4 ms (2 ms positive + 2 ms negative), 6 ms (3 + 3 ms), and 16 ms (8 + 8 ms) were compared to the control waveform of 8 ms (4 + 4 ms) in 30 experiments. Defibrillation voltage requirements with 4 ms (174 +/- 56 V) were higher (P = 0.001) compared to 8 ms (127 +/- 49 V). Defibrillation voltage requirements for the 6-ms and 16-ms waveforms were similar to the 8-ms control waveform. Delivered energies tended to be higher with the 4-ms waveform. A second series of 40 experiments were performed to compare monophasic (4 + 0 ms) and three asymmetric biphasic waveforms (4 + 2 ms, 4 + 8 ms, and 4 + 16 ms) to the symmetric control waveform (4 + 4 ms). The monophasic (2.15 +/- 1.21 J) and the 4 + 16 ms waveform (1.86 +/- 1.09 J) required higher energies (P < or = 0.05) than the control waveform (1.24 +/- 0.41 J and 0.87 +/- 0.7 J, respectively). The monophasic waveform also resulted in greater voltage requirements (223 +/- 64 V) compared to the control waveform (160 +/- 26 V) (P = 0.02). Energy and voltage requirements were similar for the 4 + 2 ms and 4 + 8 ms waveforms compared to the control. Defibrillation requirements with biphasic waveforms were affected by total and second phase duration. For waveforms with equal phase durations, total durations between 6-16 ms resulted in the lowest values for defibrillation. For waveforms with variable second (negative) phase durations, durations ranging from 50%-200% of the first phase did not affect defibrillation efficacy.

Animals↗

PubMed1996

The infectious etiology of peptic ulcer disease. Diagnosis and implications for therapy.

During the past decade, peptic ulcer disease has become recognized as multifactorial in etiology, with a major component thought to be infection of the gastric mucosa with a spiral-shaped bacterium known as Helicobacter pylori. This organism has been found to cause most cases of chronic gastritis and is clearly pathogenic in most cases of duodenal and gastric ulceration. Biologic characteristics, epidemiology, and methods of detection (invasive and noninvasive) of H. pylori are discussed from a clinical perspective. Finally, eradication of H. pylori infection is difficult because of bacterial resistance and patient noncompliance.

Helicobacter Infections↗

PubMed1995

Evaluation of the automated leucocyte count and differential from the Cell-Dyn 3500 in sickle cell disease.

Erythrocytes resistant to standard lysing reagents are known to occur in sickle cell disease. These lyse-resistant erythrocytes can cause aberrant automated leucocyte counts and differentials. The ability of the Cell-Dyn 3500 automated haematology analyser to eliminate resistant erythrocytes and accurately count and differentiate leucocytes was evaluated. Samples were obtained from paediatric patients with sickle cell disease or haemoglobin SC disease. The Cell-Dyn 3500, using impedance and optical counting with a hypotonic salt "extended lyse mode', was compared to the Cell-Dyn 3000, an optical analyser that also uses a hypotonic salt lyse, the Cell-Dyn 400, a "hard detergent lyse' impedance counter, and a reference 400-cell manual white cell differential (National committee for Clinical Laboratory Standards [NCCLS] Approved Guideline H20-A). Seventy-five samples from patients with sickle cell disease or haemoglobin SC disease were evaluated for total leucocyte count, percentage of lymphocytes, percentage of neutrophils, and nucleated red blood cells (NRBC) flags. The Cell-Dyn 3500 correlated well with Cell-Dyn 400 leucocyte counts, with a correlation coefficient of 0.95. When compared to the manual differential, the correlation coefficient for lymphocytes was 0.93 and for neutrophils 0.95. The Cell-Dyn 3500 NRBC flag had a sensitivity of 47.7% and a specificity of 80.6%. The predictive value of a positive flag was 77.7%. The Cell-Dyn 3500's extended lyse mode clearly enhances the accuracy of leucocyte counts and differentials in patients with sickle cell disease.

Anemia, Sickle Cell↗

PubMed1993

Ventricular defibrillation in canines with chronic infarction, and effects of lidocaine and procainamide.

Prior studies in dogs with normal hearts have demonstrated that lidocaine increases but procainamide does not change the energy required for successful defibrillation. Because many postinfarct patients receiving implantable cardioverter defibrillator devices require adjunctive antiarrhythmic therapy, we have studied the effects of lidocaine and procainamide on the relationship between delivered voltage and defibrillation success in mongrel dogs 21 +/- 3 days following ligation of the left anterior descending and first diagonal coronary arteries. Internal defibrillation testing using a patch-patch electrode configuration was performed before and during the administration of saline controls (n = 10), lidocaine (n = 10) and procainamide (n = 10). The mean infarct size as determined by staining with tetrazolium was 13.4% +/- 8.3% of right and left ventricles, and did not differ significantly between groups. The 50% effective defibrillation (ED50) voltage increased with infusions of saline (16% +/- 15%), lidocaine (40% +/- 22%), and procainamide (13% +/- 15%) and the ED50 energy increased 41% +/- 44%, 104% +/- 62%, and 35% +/- 36%, respectively. However, the increase in ED50 voltages and energies were significantly greater in animals receiving lidocaine compared to those receiving either saline control or procainamide (P < 0.01). There were trends toward change of hemodynamic parameters in all animals following baseline defibrillation testing; stroke volume declined 21% +/- 16%; and mean pulmonary artery and aortic pressure increased by 22% +/- 25% and 11% +/- 15%, respectively. In conclusion, unlike our previous studies in dogs with normal hearts, in this model hemodynamic deterioration occurred with repeated fibrillation and defibrillation, and defibrillation voltage requirements increased in the control series. Taking into consideration the increase in defibrillation voltage requirements over the duration of the experiments, lidocaine increases and procainamide does not change ED50; thus, their effects are similar in normal and infarcted canine hearts.

Animals↗

PubMed1983

Extracellular recording in rat area postrema in vitro and the effects of cholinergic drugs, serotonin and angiotensin II.

Spontaneous extracellular action potentials were recorded from rat area postrema explants in vitro for up to 6 h at 35 degrees C. Their geometric mean frequency was 4.4 +/- 1.7-11 Hz (n = 120) and they were most often recorded caudal to the obex. The frequency of spontaneously discharging units could be increased three-fold by raising the KCl concentration from 5 to 15 X 10(-3) M but a claimed non-specific excitant of neurones, L-glutamic acid at 10(-7)-10(-3) M was without effect. Carbamylcholine at 10(-9)-10(-7) M increased the frequency of spontaneous units (12/13 trials) as did 10(-7) M neostigmine sulphate (14/14 trials). The effects of carbamylcholine and neostigmine were additive and were blocked by atropine sulphate at 10(-6) M (18/18 trials). Atropine also stopped the discharge of spontaneous units while D-tubocurarine did not affect unit discharge frequency. It is suggested that units responding to cholinergic drugs have an afferent input from the dorsal vagus. A number of putative transmitters, serotonin (10(-9)-10(-7) M), angiotensin II (0.5 X 10(-10)-0.5 X 10(-9) M) and dopamine (10(-9)-10(-5) M) which on indirect grounds are thought to affect area postrema neurones, were without effect on unit discharge frequency.

Afferent Pathways↗

PubMedDate not supplied

Assessment and nursing management of homebound clients with urinary incontinence.

Home care nurses are in a unique position to identify urinary incontinence and to assist patients and their families to manage urinary incontinence in the home care setting. Investigators of this study surveyed home care nurses regarding their assessment and management of elderly homebound clients with urinary incontinence. Recommendations were made to home care nurses for how to improve their care of geriatric patients with urinary incontinence.

Aged↗

PubMedDate not supplied

Urinary incontinence: assessment, treatment, and reimbursement.

Urinary incontinence is a significant problem for elderly people. Home care nurses are in a unique position to identify urinary incontinence and manage it in the home setting. Nurses can help to decrease incontinence by assessing for problems, making nursing diagnoses, and implementing appropriate treatment plans. Well-planned and documented continence care is a reimbursable nursing service for home care agencies.

Aged↗

PubMedDate not supplied

The refeeding syndrome: an approach to understanding its complications and preventing its occurrence.

The refeeding syndrome (RS) is a complication of nutritional support that potentially causes considerable morbidity and mortality. Compensatory metabolic alterations secondary to chronic starvation predispose malnourished patients to RS. Providing nutritional support initiates an intracellular shift of potassium, magnesium, and phosphate that results in many adverse effects. The literature addressing RS focuses on only one electrolyte abnormality, hypophosphatemia; however, often all three electrolyte levels are perturbed. Thus RS should be characterized as a syndrome of generalized fluid and electrolyte imbalance. Recommended electrolyte supplementation and laboratory monitoring can help prevent the disorder in susceptible patients.

Humans↗