Biomedical subjects

S Lemeshow

Publications and source records attributed to S Lemeshow.

At least 91 records · Page 5Linked to original sources

PubMed1983

A comparison of mortality and charges in two differently staffed intensive care units.

All patients entering the two differently staffed adult intensive care units (ICUs) of Baystate Medical Center were studied for a three-month period. In one unit, patients were cared for by medical and surgical resident teams specifically assigned to the ICU, who were supervised by private and teaching ICU attending physicians; patients admitted to the other ICU were cared for entirely by private physicians. Significantly lower hospital mortality rates were observed in the resident-staffed ICU for three categories of patients. Median charges for the two groups of ICU patients were either the same or higher for the resident-staffed ICU when controlling for levels of condition and treatment variables.

Adult↗

PubMed1983

High-volume crystalloid cardioplegia. An improved method of myocardial preservation.

Controlled metabolic studies were used to gauge the relative efficacy of three cardioplegic techniques in 41 patients undergoing multiple coronary artery bypass grafts. Normal-volume (1,946 +/- 155 ml) crystalloid cardioplegia (NVCC) (14 patients) was compared to high-volume (4,961 +/- 282 ml) crystalloid cardioplegia (HVCC) (14 patients) and to blood cardioplegia (BC) (1,672 +/- 127 ml) (13 patients). Measurements of coronary blood flow, coronary vascular resistance, coronary arteriovenous oxygen difference, myocardial oxygen consumption and extraction, and myocardial lactate and potassium extraction and release were all measured in the isolated, vented, paced, beating heart, before and for 20 minutes after a 1 hour arrest interval during which revascularization was completed. Additionally, during administration of the cardioplegic solution, infusion flow rate, myocardial oxygen consumption and extraction, and lactate and potassium release and uptake were noted. The results indicate that during cardioplegic administration, myocardial oxygen consumption is 1 ml O2/min with crystalloid infusion and 2.6 ml O2/min during BC infusion. The volume of crystalloid solution administered contributed to increased oxygen utilization during HVCC compared to NVCC, whereas BC promoted the highest oxygen utilization of the three groups. Potassium absorption was nearly three times greater during BC than during crystalloid administration. During myocardial reperfusion, oxygen extraction was maintained at prearrest levels only in the HVCC group. Following both NVCC and BC, oxygen extraction was depressed during the first 5 minutes of reperfusion, and the difference between the latter two groups and HVCC was significant (p less than 0.01). The rapid recovery in normal metabolic function seen with HVCC allows early discontinuation of cardiopulmonary bypass without myocardial metabolic depression.

Adult↗

PubMed1983

Mechanism of plasma catecholamine increases during coronary artery bypass and valve procedures.

Nineteen patients undergoing coronary revascularization (14 patients) or valve replacement (five patients) were studied to monitor the catecholamine levels following operation and for each of three consecutive postoperative days. A significant (p less than 0.01) elevation was observed in both the serum norepinephrine and epinephrine levels immediately following operation, with both responding in a similar fashion (r = 0.804, p = 0.016). While epinephrine returned to control levels within 3 days of operation, the norepinephrine levels remained above control. The elevation in catecholamines associated with cardiac operation is presumed to be secondary to (1) the stress of surgical trauma and (2) the influence of cardiopulmonary bypass, with its attendant hypothermia and hemodynamic alterations. A comparative analysis was performed of (1) the type of operation, (2) the sex of the patient, (3) the presence of postoperative arrhythmia, (4) the history of receiving propranolol, (5) the duration of cardiopulmonary bypass, (6) the duration of operation, and (7) the volume of fluid gradient absorbed during operation. None of these parameters except the sex of the patient was significantly related to the change in either norepinephrine or epinephrine associated with the operation. There was a significantly (p less than 0.05) higher epinephrine level at day 2 and 3 following operation in women than in men. None of the 19 patients had postoperative complications except for arrhythmias, which developed in nine patients and were not associated with the catecholamine responses. It is concluded that peak catecholamine stimulation does not reflect the ease of postoperative recovery. The duration of bypass and operation were also not directly related to the level of stimulation. It is apparent that there are multiple factors which combine to influence catecholamine secretion during cardiopulmonary bypass.

Adult↗

PubMed1982

A review of goodness of fit statistics for use in the development of logistic regression models.

Several statistics have recently been proposed for the purpose of assessing the goodness of fit of an estimated logistic regression model. These statistics are reviewed and compared to other, less formal, procedures in the context of applications in epidemiologic research. One statistic is recommended for use and its computation is illustrated using data from a recent study of mortality of intensive care unit patients.

Humans↗

PubMed1982

Predicting mortality of intensive care unit patients. The importance of coma.

Five hundred fifty-eight patients from two general medical/surgical ICUs were studied with respect to the relationship of mortality and length of stay to 18 treatment and condition variables. Two multiple logistic regression models were developed to estimate the probability of mortality. One was a model incorporating main effects only; the other allowed for the interaction of pairs of variables. For ICU mortality, the best predictive variables using the main effects model were coma, cardiopulmonary resuscitation (CPR) in the ICU, and shock. With the interactive model, the variables selected were shock plus coma, and CPR in the ICU.

Coma↗

PubMed1982

Hospital charges and long-term survival of ICU versus non-ICU patients.

Hospital charges and long-term (2 yr) survival were evaluated for 558 ICU and 124 non-ICU patients from a large community hospital. Although the ICU patients represented only 9.5% of total hospital admissions, they incurred nearly 30% of the total hospital charges and had a median hospital charge of greater than four times the non-ICU comparison group. For the ICU patients, the overall in-hospital mortality rate was 17.3% and the overall 2-yr mortality rate was 35.6%, whereas the non-ICU group rates were 3.4 and 14.8% respectively. Given a patient was discharged alive from the hospital, the proportion surviving an additional 2 yr was strikingly similar for the two groups (83.3% of ICU patients and 89.1% of non-ICU patients). Because of excess mortality for ICU patients, discharged from a community hospital was not significantly greater than for non-ICU patients, the long-term outlook for discharged patients after receiving intensive care is not as bleak as is generally assumed.

Adult↗

PubMed1982

A longitudinal study of blood pressure in a national survey of children.

Blood pressure changes over a three- to four-year period were studies in a cohort of 2,168 children examined during the US Heath Examination Survey. The sample used is a representative subset of a national probability sample. Significant positive correlations between initial and follow-up blood pressures were observed. In addition, relatively obese children tended to demonstrate higher blood pressures within age-race-sex specific subgroups.

Adolescent↗

PubMed1982

The epidemiologic assessment of male reproductive hazard from occupational exposure to TDA and DNT.

Dinitrotoluene (DNT) and toluene diamine (TDA) are intermediates in the production of toluene diisocyanate and polyurethane plastics. Some reproductive effects in rodents have been reported; and the National Institute for Occupational Safety and Health reported probable reproductive toxic effect to humans after a preliminary survey. Accordingly, 84 workers exposed to DNT/TDA (classified by intensity and recency of exposure) and 119 nonexposed workers were studied at Olin's chemical complex at Lake Charles, La. Each worker was the subject of a physician's urogenital examination, a reproductive and fertility questionnaire, an estimation of testicular volume, an assessment of serum follicle-stimulating hormone, and an analysis of semen for sperm count and morphology. No differences were found between the exposed and control groups among any of these variables. Although both TDA and DNT are readily absorbed (percutaneous, inhalation, ingestion), they did not present detectable reproductive hazard to the workers.

Adult↗

PubMed1981

The optimal potassium concentration in cardioplegic solutions.

High-energy phosphates provide a sensitive index of myocardial preservation. This experiment was designed to use this index in order to assess the efficacy of various potassium concentrations in a crystalloid cardioplegic solution in protecting the myocardium during hypothermic ischemic arrest. The in vivo ischemic pig-heart model was used, measuring left ventricular levels of adenosine triphosphate (ATP) before, during, and after a two-hour arrest period and after 30 minutes of reperfusion. Thirty-eight animals were divided into seven groups of 5 to 6 animals each. Each group received a different potassium concentration in the cardioplegic solution, namely, 5, 10, 15, 20, 25, 30, and 35 mEq/L. The results were as follows: the ATP moiety was best preserved during ischemia and reperfusion in the 15 mEq/L group, while it remained significantly lower in the 5 mEq/L group. The 10, 20, 25, 30, and 35 mEq/L groups showed an intermediate range of ATP preservation. We conclude from these results that cardioplegic solutions containing 5 mEq/L of potassium seem to be inadequate for myocardial preservation during ischemic arrest; that solutions with 15 mEq/L of potassium may offer the best myocardial protection of all concentrations tested; and that solutions with potassium concentrations of 15 and 35 mEq/L are significantly better than normokalemic (5 mEq/L) cardioplegic solutions.

Adenosine Triphosphate↗

PubMed1981

Factors affecting trauma center utilization in Illinois.

The Illinois Trauma System has served as a prototype for many of the advanced emergency medical services systems developed during the past decade. The Illinois Trauma Study uses a cross-sectional research design to assess the trauma patient utilization patterns at hospitals in Illinois. Data were collected from 33 Trauma Centers and 43 nonsystem hospitals for the time interval July 1973-June 1974. Results indicated that 45.5 per cent of patients admitted with specified trauma conditions were hospitalized at Trauma Centers. When adjustment is made for differences in the size of hospitals, a 50 per cent excess in patient capture is found at Trauma Centers. This excess utilization found in Trauma Centers for this sample of trauma victims was not found among all patients admitted to these hospitals. Factors found to be associated with high Trauma Center use are race (high use among nonwhites), injury severity, evening admission to hospital and vehicular injury. Also, approximately two thirds of trauma patients that were admitted to intensive care units or transferred from other hospitals were hospitalized at Trauma Centers.

Adolescent↗

PubMed1981

The metabolic consequences of blood and crystalloid cardioplegia.

Twenty-seven patients undergoing elective coronary revascularization were evaluated by the following metabolic studies: coronary blood flow and vascular resistance, myocardial oxygen consumption and extraction, and lactate and potassium extraction, uptake and release. Patients were divided into two groups, 14 having crystalloid potassium (25 mEq/l) and 13 blood potassium (25 mEq/l) cardioplegic arrest. The groups were comparable in terms of preoperative demographic characteristics and the duration of cardioplegic arrest, which averaged 63.8 minutes in the crystalloid group and 65.6 minutes in the blood group. There were obvious differences in the effects of the two cardioplegic solutions during administration. Crystalloid cardioplegia had a significantly higher infusion rate and, accordingly, a lower vascular resistance, whereas blood cardioplegia provided increased oxygen use during administration. The amount of lactate released during cardioplegic infusion was greater in the crystalloid than in the blood group, while the amount of potassium absorbed by the heart was greater with blood. During reperfusion, coronary blood flow, vascular resistance and myocardial oxygen consumption were not significantly different in the two groups. The myocardial oxygen extraction, as manifested by a narrowed arteriovenous oxygen difference, was decreased compared with control in both groups during early reperfusion, and the extraction curves for both groups returned to control values by 20 minutes. Myocardial lactate release occurred in both groups during early reperfusion and there was no significant distinction between the two groups. Potassium release occurred during reperfusion in both groups, but significantly more potassium was released in the blood group than in the crystalloid group. We conclude that both methods of myocardial preservation provide adequate protection for 1 hour of ischemic arrest and nearly equal depression in oxygen use. Crystalloid cardioplegia allows greater lactate production during the arrest interval, whereas blood allows a greater potassium absorption by the heart during arrest but releases more potassium during reperfusion.

Adult↗

PubMed1978

A computer program for stepwise logistic regression using maximum likelihood estimation.

A computer program has been written which performs a stepwise selection of variables for logistic regression using maximum likelihood estimation. The selection procedure is based on likelihood ratio tests for the coefficients. These tests are used in a forward selection and a backward elimination at each step. The use of the program is illustrated by several examples.

Computers↗

PubMed1974