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M M Brown

Publications and source records attributed to M M Brown.

At least 73 records · Page 4Linked to original sources
PubMed1999

Evidence-based medicine, utilities, and quality of life.

Evidence-based medicine provides the highest quality of information for medical practitioners. At the top of the pyramid of evidence-based medicine are the prospective, randomized clinical trials and meta-analysis. Evidence-based medicine can be incorporated with quality-of-life parameters; the latter can be quantified using utility theory. With utility theory, utility values range from 0.0 (death state) to 1.0 (perfect health state). The higher the utility value, the better a person's quality of life. Interventional treatment can change the utility level experienced by a patient. A change in utility value induced by an interventional treatment can be amalgamated with the duration of the treatment effect to provide the number of quality-adjusted life-years (QALYs) gained by a specific treatment (QALYs = [gain in utility value] x [duration of treatment effect]). Thus, this formula takes into account both the improvement in quality of life and the improvement in length of life gained by a treatment. The number of QALYs gained by a treatment can then be incorporated with medical costs (discounted for the time value of money) to arrive at a final common denominator of $/QALY (cost per QALY). The parameter $/QALY can be used to compare the cost-effectiveness of interventional treatments across diverse specialties in medicine. In essence, this methodology allows a measure of the cost-effectiveness of a treatment that incorporates the highest quality of scientific information, clinical efficacy, patient quality-of-life preferences, and realistic costs.

Aged↗
PubMed1999

Fatal cerebral reperfusion hemorrhage after carotid stenting.

BACKGROUND: The hyperperfusion syndrome is a recognized complication of carotid endarterectomy. Reports of cerebral hyperperfusion injury following internal carotid artery (ICA) angioplasty are few, and this complication has never been reported following internal carotid stenting. CASE DESCRIPTION: A 68-year-old normotensive man was referred to our hospital for assessment 5 months after experiencing a left hemispheric ischemic stroke. Angiography confirmed 95% stenosis of the left ICA. Left carotid percutaneous transluminal stenting was performed without any initial complications. Color Doppler ultrasound of the ICA immediately after stenting revealed an elevated peak systolic velocity of 2.3 m/s, in the absence of significant vessel stenosis or spasm on angiography. Seven hours after the procedure, the patient suddenly deteriorated. CT of the brain revealed extensive intracerebral hemorrhage (ICH), and he subsequently died 18 days later. There was no history of headache or seizure activity, and his blood pressure was only mildly elevated at the time of the deterioration. This is the first report of ICH after internal carotid stenting. CONCLUSIONS: ICH may occur as a hyperperfusion phenomenon after internal carotid stenting, in the presence of mild to moderate arterial hypertension, without being heralded by any of the typical symptoms of the hyperperfusion syndrome. Patients with increased velocities on color Doppler ultrasound of the ICA after angioplasty should be monitored closely for features of cerebral hyperperfusion injury. Further studies are warranted to determine whether more aggressive treatment of mild to moderate hypertension after carotid stenting would reduce the likelihood of this potentially fatal complication.

Aged↗
PubMed1999

Should we screen for familial intracranial aneurysm?

BACKGROUND AND PURPOSE: The purpose of this study was to establish whether individuals with a family history of >/=2 first-degree relatives with intracranial aneurysm should be offered screening for aneurysm. METHODS: We derived 3 theoretical models and calculated the outcomes of screening with magnetic resonance angiography (MRA) followed by digital subtraction angiography (DSA) if MRA was positive (model 1), screening with DSA alone (model 2), and not screening (model 3). Screening was repeated at intervals of 10 years, and aneurysms detected were treated surgically. We assumed a prevalence of aneurysm of 9.8% (95% CI, 8.9% to 10.6%) in the population screened, an annual rupture rate of asymptomatic aneurysm of 0.8% (95% CI, 0.4% to 1.5%), and a 75% chance of poor outcome from rupture. We assumed the sensitivity and specificity of MRA were each 90% and the risk of DSA was 0.1%. The risk of surgery was taken as 5.1%. RESULTS: Screening 1000 individuals on 3 occasions with MRA and DSA or with DSA alone followed by surgery resulted in poor outcome in 14 and 18 individuals, respectively, over 30 years. Without screening, poor outcome occurred in 15 individuals over the same period of time. CONCLUSIONS: Screening is not an effective way of reducing morbidity and mortality from ruptured intracranial aneurysm in individuals with a history of >/=2 affected first-degree relatives with ruptured intracranial aneurysm unless the expected incidence of asymptomatic aneurysm is considerably >10%.

Adult↗
PubMed1999

Measurement of initial N-acetyl aspartate concentration by magnetic resonance spectroscopy and initial infarct volume by MRI predicts outcome in patients with middle cerebral artery territory infarction.

BACKGROUND AND PURPOSE: (1)H MR spectroscopy can be used to study biochemical changes occurring in the brain in stroke. We used it to examine the relationship between metabolite concentration (N-acetyl aspartate [NAA], lactate, cholines and creatines), size of infarct, clinical deficit, and 3-month clinical outcome in patients with middle cerebral artery (MCA) territory infarction. METHODS: Thirty-one patients with acute MCA territory infarction were recruited within 72 hours of the onset of symptoms. Single-voxel short echo time stimulated echo acquistion mode spectroscopy was used to obtain metabolite data from the infarct core. Metabolite concentrations were determined with use of variable projection time domain-fitting analysis. Infarct size was determined with T2-weighted images. Patient outcome groups at 3 months were "independent," "dependent," or "dead." RESULTS: All patients (100%; 95% CI 75% to 100%) who had an infarct >70 mL did poorly. Eighteen of 20 patients (90%; 95% CI 68% to 99%) with a core NAA concentration <7 mmol/L did poorly at 3 months, whereas 7 of 11 patients (64%; 95% CI 31% to 89%) with an initial NAA concentration >7 mmol/L did well. Combining these results showed that all patients who had an initial infarct volume >70 mL did poorly, irrespective of the NAA concentration. Of those patients with infarcts <70 mL, those who had a core NAA concentration >7 mmol/L did well (88%; 95% CI 47% to 100%), whereas those with a lower NAA concentration did poorly (80%; 95% CI 44% to 97%). There was no association between other metabolite concentrations and outcome. CONCLUSIONS: Infarct volume and NAA concentration can together predict clinical outcome in MCA infarction in humans.

Adult↗
PubMed1999

Cost-effectiveness of treatment for threshold retinopathy of prematurity.

OBJECTIVE: Retinopathy of prematurity (ROP) is a leading cause of adverse visual outcomes in premature infants. Both laser photocoagulation and cryotherapy have been demonstrated in clinical trials to be efficacious in reducing the incidence of visual loss occurring secondary to threshold ROP. Visual data recently have become available concerning the long-term clinical efficacy of both treatments, as have data concerning the utility value of visual states in general. Accordingly, we undertook an analysis to ascertain the cost-effectiveness of laser photocoagulation and cryotherapy in the treatment of threshold ROP. DESIGN: A computer simulation economic model is presented to evaluate the cost-effectiveness of cryotherapy and laser photocoagulation therapy, compared with the natural course of the disease, for treating premature infants with threshold ROP. The model applies long-term visual data from previous clinical trials, utility analysis, decision analysis, and economic principles, such as present value analysis, to account for the time value of money to arrive at a cost per quality-adjusted life-year (QALY) gained. OUTCOME MEASURES: Cost per QALY gained from laser therapy and cryotherapy. RESULTS: Laser photocoagulation therapy for threshold ROP costs $678 1998 US dollars (at a 3% discount rate to account for the time value of money) for each QALY gained from treatment. Cryotherapy for the same disease costs $1801 per QALY at a similar discount rate. CONCLUSIONS: From the point of view of cost-effectiveness, laser therapy seems to have an advantage over cryotherapy for the treatment of threshold ROP.

Computer Simulation↗
PubMed1999

Evidence-based medicine and cost-effectiveness.

Most available medical management techniques compare the practice patterns of providers with other providers but overlook the inherent value of interventional medical therapies to patients and society. The authors present a methodology for objectively evaluating the quality and cost-effectiveness of medical interventional therapies, and comparing them to each other using the common denominator of cost per quality-adjusted life-year ($/QALY). Advantages of this methodology include the fact that it: (1) compares the cost-effectiveness of different treatment regimens, (2) incorporates patient preferences, (3) employs evidenced-based medical data, information that is most reliable and reproducible, (4) factors in the effect of treatment on the quality of life and length of life, (5) offers an evaluation of the clinical efficacy of a treatment, (6) identifies both superior and marginal treatments, (7) maximizes the effective use of scarce resources, and (8) simplifies the understanding of health care procedures for consumers, payers, and providers.

Cost-Benefit Analysis↗
PubMed1998

Patient perceptions of quality-of-life associated with bilateral visual loss.

PURPOSE: To ascertain whether patients with unilateral visual loss to a specific level are able to approximate the degree of impairment of quality-of-life experienced by patients with bilateral visual loss to the same level. METHODS: One hundred thirty-three study group patients with (1) visual loss to 20/40 or worse in at least one eye, and (2) a marked difference between the visual acuities in their two eyes, were polled using the time tradeoff method of utility value measurement. All patients were asked to assume that the visual acuity in both of their eyes was as poor as the visual acuity in their worst seeing eye. These utility values were then compared to those obtained from a control group of 173 patients with known utility values who had similar bilateral visual loss. Both the study and control groups were stratified into 4 levels of visual loss (20/40 to 20/50, 20/60 to 20/100, 20/200 to 20/400, and counting fingers to light perception). RESULTS: Mean utility values for the study group ranged from 0.47 to 0.71. Patients with unilateral visual loss, given the assumption of bilateral visual loss to the same degree, routinely demonstrated no significant difference in utility preferences as compared to patients with true bilateral visual loss to the same level. CONCLUSIONS: Patients with unilateral visual loss can very accurately estimate the degree of impairment of quality-of-life that would result if visual loss to a similar degree occurred in the remaining eye with better vision.

Activities of Daily Living↗
PubMed1998

Pneumoperitoneum as a risk factor for endobronchial intubation during laparoscopic gynecologic surgery.

UNLABELLED: Patients undergoing gynecological surgery under laparoscopic guidance usually receive general anesthesia with endotracheal intubation and mechanical ventilation. The creation of a pneumoperitoneum and the Trendelenburg position, both of which are used to improve visualization, are associated with cephalad movement of the diaphragm. This may increase the risk of endobronchial intubation. We studied the change in the distance from the tip of the endotracheal tube (ETT) to the carina with a fiberoptic bronchoscope in 30 patients aged 21-40 yr who were undergoing laparoscopic tubal ligation (n = 28) or hysterectomy (n = 2). Measurements were taken in the supine and Trendelenburg positions before and after pneumoperitoneum. The average distance from the ETT to the carina in the supine position was 2.1 +/- 0.8 cm and in the Trendelenburg position was 1.8 +/- 0.8 cm (P = not significant). After insufflation of the abdominal cavity, the mean distance decreased to 0.7 +/- 1.4 cm in the supine position (P < 0.05) and was associated with endobronchial intubation in eight patients. The addition of the Trendelenburg position to an established pneumoperitoneum resulted in minimal displacement (0.54 +/- 1.4 cm, P < 0.05) and one additional endobronchial intubation. We conclude that the insufflation of gas in the abdominal cavity, and not the change in patient position, is the main risk factor for endobronchial intubation in patients undergoing laparoscopic gynecologic surgery. IMPLICATIONS: This study demonstrated that in anesthetized women, the insufflation of gas into the abdomen during laparoscopy for gynecologic surgery is the main risk factor for migration of the endotracheal tube into a bronchus.

Adult↗
PubMed1998

Managing latex allergy in the cardiac surgical patient.

Latex allergy affects about 1% of the general population and between 10% and 17% of health care workers. The severity of a latex allergic reaction can range from contact dermatitis to anaphylaxis and death. Critical care personnel must be able to identify cardiac surgical patients at risk for a latex allergy and supply alternative equipment, and medication. In addition, knowledge and provision of emergency treatment of a Type I latex reaction is paramount. Critical care staff need to educate both the patient and the family about latex allergy, including latex allergy testing and community resources.

Critical Care↗
PubMed1998

Mouse strain differences in oral operant ethanol reinforcement under continuous access conditions.

The present experiment examined ethanol self-administration in C57BL/6J (C57) and DBA/2J (DBA) mice using a continuous access operant procedure. Adult male C57 and DBA mice were initially trained to perform a lever press response to obtain access to 10% w/v sucrose solution. Subsequently, the mice were placed in operant chambers on a continuous (23 hr/day) basis with access to food (FR1), 10% v/v ethanol (FR4), and water from a sipper tube. C57 mice displayed greater rates of responding on the ethanol-associated lever compared with DBA mice. Responding on the food lever was the same in both strains, but DBA mice consumed greater amounts of water. C57 mice consistently displayed both prandial and nonprandial episodes (bouts) of ethanol responding. DBA mice did not respond for ethanol in bouts. Following 50 consecutive sessions, ethanol concentration was altered every 5 days. Response patterns were determined using 0, 5, 10, 20, and 30% v/v ethanol concentrations. C57 mice displayed concentration-dependent responding on the ethanol lever showing that ethanol was functioning as an effective reinforcer in this strain. In contrast, responding on the ethanol lever by DBA mice did not change as a function of ethanol concentration. Saccharin (0.2% w/v) was subsequently added to the ethanol mixture, and responding was examined at 0, 5, 10, and 20% ethanol concentrations. Overall, ethanol lever responding was increased in both strains. As before, C57 mice showed higher levels of ethanol responding, compared with DBA mice. C57 mice also showed higher responding for saccharin alone. These results are consistent with findings that suggest orally administered ethanol is a more effective reinforcer in C57 mice than in DBA mice. Furthermore, C57 mice engage in ethanol-reinforced responding over a broader range of conditions than DBA mice.

Alcohol Drinking↗
PubMed1998

Treatable lesions demonstrated on vertebral angiography for posterior circulation ischaemic events.

Angiography after a posterior circulation ischaemic event is often not considered because of the perception that it will not alter patient management. We identified 53 patients investigated with vertebral angiography over a 5 year period. This was significantly abnormal in 32 patients (60%). Five (9%) had vertebral artery dissections, nine (17%) had unilateral vertebral artery occlusion, two had a basilar artery disease. 16 (30%) had vertebral artery stenosis. 12 stenoses were considered suitable for percutaneous transluminal angioplasty (23%). 11 patients were anticoagulated (21%). There was no significant correlation between clinical features, site of infarct or the presence of carotid stenosis that would have allowed the prediction of the findings in the posterior circulation. Our results indicate that using vertebral angiography to investigate posterior circulation ischaemia will identify a significant number of potentially treatable lesions.

Aged↗
PubMed1997

Laryngotracheal anesthesia device as jet ventilation cannula for removal of fragmented intratracheal T-tube.

For tracheotomy procedures with general anesthesia, adequate surgical exposure, oxygenation, and ventilation of the lungs can be obtained by different techniques. We present a method of jet ventilation with use of a modified laryngotracheal anesthesia (LTA) device as a jet ventilation cannula during retrieval of a tracheal T-tube that broke within the trachea during removal. To our knowledge, this report is the first to document friability and subsequent difficult removal of a tracheal T-tube after intubation longer than recommended by the manufacturer. It is also the first report of a new technique using a simple LTA device modification to provide oxygen insufflation or jet ventilation in this or similar situations.

Anesthesia, Inhalation↗