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Biomedical subjects

P M Simpson

Publications and source records attributed to P M Simpson.

51 records · Page 3Linked to original sources
PubMed1994

Bradycardia during anesthesia in infants. An epidemiologic study.

BACKGROUND: The frequency and morbidity of bradycardia during anesthesia in infants are not well documented. This study sought to determine the frequency of bradycardia during anesthesia in infants (0 to 1 yr) compared to that in older children, describe causes and morbidity, and identify factors that influence its frequency. METHODS: Computerized information abstracted from 7,979 anesthetic records of patients ages 0-4 yr undergoing noncardiac surgery were examined for the presence or absence of intraoperative bradycardia. To study bradycardia in infants, 4,645 anesthetics in patients aged 0-1 yr were considered. Those with bradycardia to heart rates less than 100 beats/min were examined for causes, morbidity, and treatment of the bradycardia. For analysis of influencing factors, the frequency of bradycardia in infants was related to age, sex, race, ASA physical status, surgical site (body cavity), complexity (major or minor) and duration, type of primary anesthetist, type of supervising anesthesiologist, and anesthetic agents. Logistic regression was used to estimate the significance (P < 0.05) and odds ratios for each. RESULTS: The frequency of bradycardia was 1.27% in the 1st yr of life, but only 0.65% in the third and 0.16% in the 4th yr, a significant difference. Causes of bradycardia in infants included disease or surgery in 35%, the dose of inhalation agent in 35%, and hypoxemia in 22%. Morbidity included hypotension in 30%, asystole or ventricular fibrillation in 10%, and death in 8%. Treatment involved epinephrine in 30% and chest compression in 25%. Associated factors included an ASA physical status of 3-5 (vs. 1 or 2) and longer (vs. shorter) surgery. Bradycardia was less than half as likely when the supervising anesthesiologist was a member of the Pediatric Anesthesia Service as with other anesthesiologists (P < 0.001). CONCLUSIONS: Bradycardia is more frequent in infants undergoing anesthesia compared to older children and is associated with substantial morbidity. It is more likely in sicker infants undergoing prolonged surgery and less likely when a pediatric anesthesiologist is present.

Age Factors↗
PubMed1993

Modulation of the QT interval: effects of graded exercise and reflex cardiovascular stimulation.

During exercise, as heart rate (HR) increases, the QT interval of the electrocardiogram shortens. The mechanism(s) involved in this QT shortening has not been clearly defined. To distinguish the influence of increased circulating catecholamines from myocardial efferent stimulation, the relationship between HR and QT interval was investigated during exercise and cardiovascular reflex stimulation in cardiac transplant patients and normal control subjects. Because of cardiac denervation, increases in HR in these patients are solely due to circulating catecholamines and thus allow isolation of their effect on the QT interval. Twenty-one cardiac transplant patients were studied and compared with 16 normal control subjects. The QT-HR relationship was determined according to an exponential model during treadmill exercise in both groups [QT = 0.12 + 0.492e(-0.008.HR) and QT = 0.12 + 0.459e(-0.007.HR) in normal subjects and transplant patients, respectively] and was statistically similar between groups, suggesting similar QT interval shortening in both groups. During cold pressor and Valsalva maneuvers, HR increased significantly in normal subjects only, whereas QT interval changed minimally in both groups. These results suggest that during exercise the QT interval is influenced predominantly by increases in circulating catecholamines rather than by neurally mediated reflex autonomic changes.

Adult↗
PubMed1993

Creation of state-level Medicare database for healthcare evaluation applications.

The Health Care Quality Improvement Initiative (HCQII) of the Health Care Financing Administration (HCFA) calls for Professional Review Organizations (PROs) to undertake pattern analysis of large administrative datasets for the purposes of quality of care assessment. The limitations of such administrative databases (primarily the MEDPAR file and derivatives thereof) include impoverished information regarding clinical attributes of Medicare enrollees and the process and outcome of their healthcare. This paper describes preliminary efforts to address this problem by the creation of a database, the PRO Concatenated Database (PCD), from the pooled implicit judgment review data of four Peer Review Organizations (PROs). The data elements comprising the PCD were carefully selected to provide important information regarding quality and appropriateness of care. Preliminary inter-state comparative studies employing the PCD are discussed. A method is also described by which the analytical power of state-level databases may be enhanced by linkage to state-level Modeled MEDPAR data which are issued by HCFA and contain patient-level risk-adjusted mortality data. This approach to the acquisition of data whose clinical content is enriched may prove to be particularly useful to the PRO community during the pattern analysis phase of the HCQII. Such analyses will evolve into more detailed studies involving primary data collection followed by dissemination of the results to local healthcare providers. In this manner, the PCD may facilitate rapid feedback regarding the effectiveness of healthcare delivery to the local community.

Aged↗
PubMed1992

Extracorporeal membrane oxygenation and early-onset group B streptococcal sepsis.

Recently, extracorporeal membrane oxygenation (ECMO) has been used as rescue therapy for newborns with overwhelming early-onset group B streptococcal sepsis. To determine which clinical factors best predict mortality and to evaluate the outcome of this therapy, a retrospective examination of the clinical course and outcome of ECMO-eligible newborns with early-onset group B streptococcal sepsis was undertaken. The study period was divided into two phases based on when ECMO was initially used at Kosair Children's Hospital as therapy for septic neonates. Phase 1 (pre-ECMO) was the period from January 1, 1982, through June 15, 1986, and phase 2 (ECMO) from June 16, 1986, through December 31, 1989. Newborns with gestational age greater than or equal to 34 weeks, birth weight greater than or equal to 2000 g, and evidence of early-onset group B streptococcal sepsis were eligible for study. Only newborns who received mechanical ventilation were evaluated. Sixteen patients from phase 1 met the above criteria. Of those, 10 exhibited no sign of hypotension and all survived. Of the 6 patients with hypotension, 3 died. Forty patients were identified from phase 2. Seven patients remained normotensive and all survived. Thirty-three patients were hypotensive, of which 15 received ECMO and 13 survived. Of the 18 who did not receive ECMO, 7 died. Regarding all hypotensive newborns, those who did not receive ECMO had a trend toward lower survival (P less than .06) and were more likely to die if they were of lower birth weight, manifested a persistent acidosis (pH less than or equal to 7.25), and had an absolute neutrophil count less than 500 cells/mm3.(ABSTRACT TRUNCATED AT 250 WORDS)

Acidosis↗
PubMed1991

Effect of extracorporeal membrane oxygenation on leukocyte function in neonates.

The impact of extracorporeal membrane oxygenation (ECMO) on neonatal leukocyte content and function was examined in six patients. Patients were treated with ECMO for a mean of 134 h (range 44-246 h). Absolute neutrophil counts decreased from 14679 +/- 2291/mm3 to 7791 +/- 1672/mm3 after 2 h of ECMO. However, neutrophil phagocytosis and oxidative burst remained unchanged during the first 48 h of bypass. Monocyte counts also decreased during bypass, and at times were undetectable in 50% of patients. Monocyte HLA-DR content was decreased compared to normal cord blood prior to initiation of ECMO, and remained low throughout ECMO. However, the content increased significantly after termination of bypass. Plasma C3a levels increased transiently, paralleled by an increase in neutrophil CR3 expression. While moribund infants had some impairment of host defenses prior to ECMO, there was no further impact of ECMO per se on the parameters measured, other than transient complement activation and decreased monocyte counts.

Complement Activation↗
PubMed1991

Cholinesterase inhibition in the scopolamine model of dementia.

Scopolamine produces a satisfactory model of the attentional and secondary memory deficits seen in Alzheimer's disease (AD) that can be used to screen compounds for potential therapeutic usefulness. Physostigmine, which is known to enhance memory in AD, produced marked and widespread antagonism of the scopolamine-induced impairments, indicating the sensitivity of the model and establishing its relevance for the clinical situation. HP 029, a novel anticholinesterase, also exhibited widespread potency in the model, and in an international trial with patients with AD, it subsequently showed improvement on similar measures, demonstrating the predictive use of the scopolamine model.

Alzheimer Disease↗
PubMed1990

HLA antigens in lichen sclerosus et atrophicus.

Several reports have found conflicting data regarding the association between lichen sclerosus et atrophicus (LSA) and HLA types. Association with HLA-A31 and -B40 has been noted, whereas another report found no correlation. We are the first to specifically examine HLA types in white patients in the United States. We have found a significant association between LSA and HLA-A29 and -B44 individually and an even stronger association with the combination of A29 and B44. A review of previous LSA-HLA studies, as well as several reports of HLA typing in familial LSA, is discussed, with consideration given to possible reasons for the discrepancies among the various studies.

Adolescent↗
PubMed1989

The effects of moclobemide on cognition.

The mental ability of the elderly is frequently compromised by age-associated cognitive declines, which may be result of cholinergic deterioration. Depression is accompanied by cognitive performance impairments, and recent work suggests these may be more severe in the elderly. Antidepressants with anticholinergic side-effects, such as the tricyclics, should thus be used with caution in the elderly. A potential advantage of new antidepressants which are relatively free of anticholinergic effects, may be in a reduced liability to impair cognition, whilst maintaining at least equal antidepressant potency. The effects of moclobemide, a novel reversible monoamine oxidase inhibitor, have been studied in both young and elderly volunteers using computerized assessment of a variety of aspects of cognition. In the young the drug was studied within a scopolamine model of the cognitive effects of aging and dementia, while, in the elderly, the cognitive effects of the drug were compared to those of trazodone. In the scopolamine model, moclobemide was significantly superior to placebo and other compounds in antagonizing the cognitive impairments resulting from cholinergic blockade. In the elderly, some improvements were found with moclobemide, particularly in memory, and while an impairment to vigilance was observed, this effect was considerably less marked than with trazodone. Moclobemide would thus appear to have an advantage over antidepressant compounds such as the tricyclics of having a lower liability to impair cognitive efficiency. However, to establish this in depressed patients it will be necessary to incorporate sensitive assessments of cognitive efficiency into trials of the drug in young and elderly populations.

Benzamides↗
PubMed1986

Effects of meclofenamate and acetaminophen on abdominal pain following tubal occlusion.

To test the hypothesis that the postoperative abdominal pain of tubal occlusion is mediated by prostaglandins, the effects of meclofenamate, a potent inhibitor of cyclooxygenase, on postoperative analgesia and incidence of abdominal pain were compared with those of acetaminophen, a weak inhibitor of prostaglandin activity. One hundred patients undergoing tubal occlusion under local anesthesia were studied. The patients were randomly divided into four equal groups: control; acetaminophen, 1300 mg; meclofenamate, 100 mg; meclofenamate, 200 mg. The fallopian tubes were occluded by electrocautery in 47 patients and by application of Falope rings in 53 patients. Both acetaminophen and meclofenamate provided substantial analgesia for 4 hours after the operation (p less than 0.05). Meclofenamate reduced the incidence of abdominal pain by one half (p less than 0.02), but acetaminophen did not. These results suggest that a portion of pain relief achieved by meclofenamate may be due to suppression of myosalpingian and/or myometrial contractions, a process mediated by prostaglandins.

Acetaminophen↗
PubMed1975

Evidence of gentamicin nephrotoxicity in patients with renal allografts.

Renal damage was assessed by measuring urinary enzyme excretion in 180 patients with renal allografts. Thirty-six of these patients were studied during 53 courses of treatment with antimicrobial agents which was the only antimicrobial agent which was associated with an increase in urinary enzyme activity. There was usually also evidence of reduced renal function. Renal morphological changes similar to those produced by gentamicin in rats were observed in human allograft biopsy specimens obtained during gentamicin treatment.

Acetylglucosaminidase↗