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J R Morton

Publications and source records attributed to J R Morton.

At least 37 records · Page 2Linked to original sources
PubMed1992

Multivariate prediction of in-hospital mortality associated with coronary artery bypass graft surgery. Northern New England Cardiovascular Disease Study Group.

BACKGROUND: A prospective regional study was conducted to identify factors associated with in-hospital mortality among patients undergoing isolated coronary artery bypass graft surgery (CABG). A prediction rule was developed and validated based on the data collected. METHODS AND RESULTS: Data from 3,055 patients were collected from five clinical centers between July 1, 1987, and April 15, 1989. Logistic regression analysis was used to predict the risk of in-hospital mortality. A prediction rule was developed on a training set of data and validated on an independent test set. The metric used to assess the performance of the prediction rule was the area under the relative operating characteristic (ROC) curve. Variables used to construct the regression model of in-hospital mortality included age, sex, body surface area, presence of comorbid disease, history of CABG, left ventricular end-diastolic pressure, ejection fraction score, and priority of surgery. The model significantly predicted the occurrence of in-hospital mortality. The area under the ROC curve obtained from the training set of data was 0.74 (perfect, 1.0). The prediction rule performed well when used on a test set of data (area, 0.76). The correlation between observed and expected numbers of deaths was 0.99. CONCLUSIONS: The prediction rule described in this report was developed using regional data, uses only eight variables, has good performance characteristics, and is easily available to clinicians with access to a microcomputer or programmable calculator. This validated multivariate prediction rule would be useful both to calculate the risk of mortality for an individual patient and to contrast observed and expected mortality rates for an institution or a particular clinician.

Aged↗
PubMed1991

A regional prospective study of in-hospital mortality associated with coronary artery bypass grafting. The Northern New England Cardiovascular Disease Study Group.

OBJECTIVE: A prospective regional study was conducted to determine if the observed differences in in-hospital mortality rates associated with coronary artery bypass grafting (CABG) are solely the result of differences in patient case mix. DESIGN-Regional prospective cohort study. Data including patient demographic and historical data, body surface area, cardiac catheterization results, priority of surgery, comorbidity, and status at hospital discharge were collected. This study presents data for 3055 CABG patients between July 1, 1987, and April 15, 1989. SETTING: This study includes data from all surgeons performing cardiothoracic surgery in Maine, New Hampshire, and Vermont; the data were collected from five regional medical centers. PATIENTS: Data were collected from all consecutive isolated CABG surgery patients during the study period. MAIN OUTCOME MEASURES: Crude and adjusted in-hospital mortality rates associated with CABG. MAIN RESULTS: The overall crude in-hospital mortality rate for isolated CABG was 4.3%. The rate varied among centers (range, 3.1% to 6.3%) and among surgeons (range, 1.9% to 9.2%). Predictors of in-hospital mortality included increased age, female gender, small body surface area, greater comorbidity, reoperation, poorer cardiac function as indicated by a lower ejection fraction, increased left ventricular end diastolic pressure and emergent or urgent surgery. After adjusting for the effects of potentially confounding variables, substantial and statistically significant variability was observed among medical centers (P = .021) and among surgeons (P = .025). CONCLUSION: We conclude that the observed differences in in-hospital mortality rates among institutions and among surgeons in northern New England are not solely the result of differences in case mix as described by these variables and may reflect differences in currently unknown aspects of patient care. Understanding this variation requires a detailed understanding of the processes of care.

Adult↗
PubMed1991

Impact of influenza on morbidity in children with cystic fibrosis.

Recommendations concerning annual influenza vaccination in children suffering from cystic fibrosis (CF) are not uniform. Previous studies have shown that influenza causes a small proportion of episodes of acute respiratory deterioration in CF patients. During the 1989 Australian winter, we studied the association between serologically proven influenza infection and acute respiratory morbidity in 20 children with CF. Six children were shown to have influenza infection, four with type A and two with type B. Four of five children requiring hospital admission were shown to have influenza, but only 2 of 15 did not need admission (P less than or equal to 0.025). As well, influenza was diagnosed in 6 of 12 children who suffered acute respiratory illness leading to school absenteeism (including hospitalization), but diagnosed in no children without this degree of illness (P less than or equal to 0.025). Influenza significantly increases the incidence of hospitalization and of less serious respiratory illness in children with CF, a finding which suggests that influenza vaccine efficacy studies are necessary in this group.

Adolescent↗
PubMed1991

A numerical solution to the equilibria of the two-locus two-allele selection model.

Examination of the equilibria of the standard two-locus two-allele selection model leads to the construction of a polynomial with coefficients derived from selective values in the genotypic fitness matrix. This polynomial can be partially factored algebraically and numerical techniques are available to extract the roots of the remainder. Each root provides a possible value of the disequilibrium coefficient and the gametic frequencies at equilibrium, and these can be readily checked for stability.

Alleles↗
PubMed1987

Survival following nonpenetrating traumatic rupture of cardiac chambers.

We report the cases of 3 patients who survived cardiac chamber rupture resulting from blunt external trauma. All were drivers in motor vehicle collisions. All were seen with signs of pericardial tamponade and were treated by pericardiocentesis followed by emergency thoracotomy performed in the operating room. Ruptures of the right atrium and right and left ventricles were repaired by manual suture techniques without cardiopulmonary bypass. The cases of 37 previously reported patients who survived this injury are reviewed. We believe that patients with cardiac rupture who reach the hospital alive can often be saved by prompt diagnosis and immediate surgical treatment.

Accidents, Traffic↗
PubMed1982

Activity level and employment status after coronary bypass surgery.

Questionnaires were sent to 1,100 postoperative coronary patients to evaluate their symptoms, activity level and employment status. Ninety percent considered themselves improved and more active since surgery. Many of the patients were approaching retirement age at the time of surgery, and 20 percent of the group entered retirement postoperatively. Disregarding those who were unemployed or disabled from noncardiac illness before surgery, 82 percent of the patients either retired or returned to work after coronary surgery. From an economic standpoint, the disabled patients who have been able to return to work by virtue of the operation will generate for the economy 34 percent more than the total cost of surgery for all the patients.

Coronary Artery Bypass↗
PubMed1980

Lung growth and airway function after lobectomy in infancy for congenital lobar emphysema.

To characterize the outcome of lobectomy in infancy and the low expiratory flows which persist after lobectomy for congenital lobar emphysema, 15 subjects with this history were studied at age 8-30 yr. Total lung capacity was normal in all, but higher values (P < 0.05) were observed in nine subjects with upper lobectomy than in five subjects with right middle lobectomy. Ratio of residual volume to total lung capacity was correlated (P < 0.05) with the amount of lung missing as estimated from normal relative weights of the respective lobes. Xe(133) radiospirometry in eight subjects showed that the operated and unoperated sides had nearly equal volumes at total lung capacity, but that the operated side was larger than the unoperated side at residual volume. Perfusion was equally distributed between the two sides. Similar findings were detected radiographically in four other subjects. Forced expiratory volume in 1 s and maximal midexpiratory flow rate averaged 72 and 45% of predicted, respectively. Low values of specific airway conductance and normal density dependence of maximal flows in 12 subjects suggested that obstruction was not limited to peripheral airways. Pathologic observations at the time of surgery and morphometry of the resected lobes were not correlated with any test of pulmonary function. These data show that lung volume can be completely recovered after lobectomy for congenital lobar emphysema in infancy. The volume increase occurs on the operated side, and probably represents tissue growth rather than simple distension. The response to resection is influenced by the particular lobe resected and may be associated with decreased lung recoil near residual volume. Low expiratory flows in these subjects could be explained by several mechanisms, among which a disproportion between airway and parenchymal growth in infancy (dysanaptic growth) is most compatible with our data.

Adolescent↗
PubMed1980

Corticosteroids and malnutrition. Aspergillus lung abscess in an asthmatic child.

An adolescent developed invasive pulmonary aspergillosis in the limited form of a lung abscess. She had a weak immunologic response to the infection. Her depressed immunity was the result of prolonged corticosteroid therapy, compounded by malnutrition. In spite of this and other complications of corticosteroids, she made a full recovery from the fungal infection following treatment with amphotericin B and surgical excision of the lung abscess.

Adolescent↗
PubMed1978

Transcatheter thromboembolectomy of acute renal artery occlusion.

Direct surgery of the renal artery has been performed for the relief of acute thrombotic or embolic occlusion of the renal artery to restore adequate renal perfusion and prevent irreversible renal failure. Occasionally, severe medical disease may increase surgical risk to a prohibitive level. An angiographic technique has been devised to provide an alternative approach and has been successfully used on five occluded renal arteries in four patients, with measurable benefit.

Acute Disease↗
PubMed1977

Experiments with beta-chain variants of the hemoglobin of Mus musculus.

Starch gel electrophoretic and ultracentrifuge methods failed to demonstrate any differences between the hemoglobins of mice of the Shanghai and HBBP/Cag strains and crosses among these strains. The apparent identity of these hemoglobins is thought to stem from the contribution of Asian mice to the British mouse fancy from which the laboratory strains have Hbb-p in part descend. Maleate buffer of pH 7 or above can be used to prevent the formation of disulfide-bridged dimers of mouse hemoblobins. However, the minor electrophoretic bands of Hbb-p and Hbb-d react with approximately twice as much maleate as the major bands of each of these hemoglobins, although the minor bands like the major contain only one free cysteine group per beta chain. This can be explained by the alkylation of the epsilon-amino of lysine residue beta76, but some evidence for the alkylation of histidine in the minor band of Hbb-p is also presented.

Animals↗
PubMed1976

Effect of methylprednisolone on myocardial preservation during coronary artery surgery.

It has been proposed that a single preoperative dose of a corticosteroid may protect the myocardium from ischemic injury during open heart surgery. To test this hypothesis, a prospective, randomized, double blind study was carried out in ninety-five patients undergoing coronary bypass surgery using intermittent ischemic arrest with systemic and local hypothermia. Half the patients received 2 gm (approximately 30 mg/kg) of methylprednisolone 2 hours prior to the initiation of cardiopulmonary bypass and the other half received a placebo. Postoperative electrocardiograms and blood levels of serum creatine phosphokinase (CPK), lactic dehydrogenase (LDH), and serum glutamic oxalacetic transaminase (SGOT) were compared in the two groups. No apparent difference was noted in the number of patients with significantly elevated levels of CPK, LDH, or SGOT or in the number with positive isoenzyme patterns of CPK and LDH. Moreover, there was no significant difference in the mean values of CPK, LDH, or SGOT between the two groups. The number of patients with electrocardiographic evidence of myocardial injury (10 per cent) was the same in both groups and no difference was noted in (1) the ease with which patients could be weaned from cardiopulmonary bypass, (2) postoperative arrhythmias, (3) postoperative bleeding, (4) postoperative respiratory insufficiency, and (5) length of hospital stay. It is concluded that a single preoperative dose of 2 gm of methylprednisolone offers no demonstrable protection to the myocardium from the effects of ischemia during coronary artery bypass surgery.

Adult↗