Search PubMed⌕ Search

Biomedical subjects

C P Larson

Publications and source records attributed to C P Larson.

At least 37 records · Page 2Linked to original sources
PubMed1988

PEEP does not affect left atrial-right atrial pressure difference in neurosurgical patients.

Positive end-expiratory pressure (PEEP) has been used to prevent and treat venous air embolism in patients in the seated position undergoing neurosurgical operations. However, the safety of PEEP has recently been questioned, because of concern that PEEP might increase right atrial pressure (RAP) more than left atrial pressure, thereby predisposing patients with a probe-patent foramen ovale to paradoxical air embolism. In a prior study in dogs, the authors found that to up 10 cm H2O PEEP did not affect the interatrial pressure difference. In the present study, the authors examined the effects of 0, 5, and 10 cm H2O PEEP in 12 anesthetized neurosurgical patients positioned both supine and seated prior to operation. Measurements were made of systemic arterial pressure, RAP, mean pulmonary artery pressure (PAP), pulmonary artery wedge pressure (PAWP), and cardiac output. PAWP was higher (average 2 mmHg) than RAP in all patients. PEEP increased RAP and PAWP in patients, both seated and supine (mean 3 mmHg at 10 cm H2O), but did not affect the PAWP-RAP difference. In an additional eight patients in the seated position, the authors examined the effects of 0, 10, and 20 cm H2O PEEP during operation. PEEP again increased PAWP and RAP, but did not significantly affect the PAWP-RAP difference. The PAWP-RAP difference became negative (-1 mmHg) in one patient with 20 cm H2O PEEP. The authors conclude that levels of PEEP up to 10 cm H2O do not alter the interatrial pressure difference in seated neurosurgical patients, and, therefore, would not predispose these patients to paradoxical air embolism.

Adult↗
PubMed1986

Hemodynamic effects of positive end-expiratory pressure during continuous venous air embolism in the dog.

Positive end-expiratory pressure (PEEP) may decrease venous air embolism (VAE) by increasing venous pressure at the incision level. Because PEEP and VAE can both increase pulmonary vascular resistance, it is possible that the application of PEEP during VAE may increase right atrial pressure (RAP) relative to left atrial pressure (LAP) and thereby reverse the normal interatrial pressure gradient, allowing paradoxical air embolism in patients with a probe-patent foramen ovale. We studied atrial pressures during 0, 4, and 8 mmHg PEEP before and during continuous VAE in both supine and upright tilted dogs. Both PEEP and VAE increased pulmonary artery pressure and resistance. Prior to VAE, PEEP increased both RAP and LAP but did not affect the interatrial pressure gradient. VAE alone did not affect RAP, LAP, or the interatrial pressure gradient. Application of PEEP during VAE had similar effects as at baseline, namely an increase in RAP and LAP with no change in the interatrial pressure gradient. Although RAP exceeded LAP more frequently in the upright than in the supine dogs, the effects of PEEP and VAE on atrial pressures were similar in both groups. Our finding that PEEP and VAE did not disproportionately increase RAP compared with LAP is consistent with other studies demonstrating preservation of right ventricular function in situations of increased right ventricular afterload.

Animals↗
PubMed1986

The health status of mild to moderate intellectually handicapped adolescents.

To assist in the planning of school health services for the intellectually handicapped, a comprehensive evaluation of physical and emotional health, and social competence was completed on a group of students attending a school for educably retarded adolescents (IQ ranging form 60 to 85). This evaluation included a review of the school health records, a medical history, physical examination, and a parent-completed questionnaire assessing their child's behaviour and social competence. Abnormal physical findings included short stature (24%), impaired vision (49%) and impaired hearing (20%). In six of eight female and seven of nine male subscales of deviant behaviour, 20% or more of the students scored abnormally high (above the ninety-eighth percentile). An extreme degree of social isolation was found in 35% of the sample. Only 31% had a primary care physician, while 63% utilized episodic emergency room care. Handicapped adolescents participating in this study demonstrated a high prevalence of physical, emotional and socialization problems compounded by inadequate primary care supervision.

Adolescent↗
PubMed1980

The imported forensic expert.

A review of the experiences of one of the pioneer forensic pathologists in the United States offers an interesting insight into the possibilities of private forensic pathology in America. The author's experience includes serving as President of the National Boxing Association and the International Boxing Association, during which time he made many improvements in ring safety. His research into several areas of cases of product liability offer an insight to the wide scope of the potential of the forensic expert. This presentation reviews his activities in realms widely afield from medicine.

Animals↗
PubMed1980

Efficacy of prenatal and postpartum home visits on child health and development.

This study is a controlled evaluation of the efficacy of home visits designed to promote better child health and development for infants of working class families. Each of the 115 mother-infant pairs meeting the study criteria was assigned to one of three comparable groups: group A received home visits starting prenatally; group B received visits from six weeks post partum; and group C received no visits. Home observations were completed by an independent evaluator at 6 weeks, 6, 12, and 18 months of age. Significant differences favoring group A over groups B and C were found at each evaluation period. These included: (1) a reduced accident rate; (2) higher scores on assessments of home environment and maternal behavior; and (3) a lower prevalence of mother-infant interaction or feeding problems and of nonparticipant fathers. Aside from a reduction in the accident rate, group B did not benefit from the home visits when compared to control infants. The results support the efficacy of home visits, but only if a prenatal visit is included. These findings suggest that a unique relationship is created between the mother and home visitor and this relationship is sensitive to the timing of the initial encounter.

Child Development↗
PubMed1976

Unexpected cardiac arrest during anesthesia and surgery. An environmental study.

Medical and legal records of 41 cases of cardiac arrest that occurred during surgery were supplied by a professional liability insurance company and a review was undertaken in an attempt to identify recurring or common factors. The majority of patients in this study were healthy and required relatively routine elective surgical procedures. Only three of the patients survived the cardiac arrest and returned to normal activities. The remaining patients either died in the hospital or had a major central nervous system deficit. Hypoxia from hypoventilation and low levels of inspired oxygen appeared to be the chief cause of cardiac arrest in this study. Because of the unknown frequency of cardiac arrest during surgery, we recommend the establishment of a national registry of cardiac arrest cases that occur in surgical patients, in order to monitor incidence, causes, and outcome. Only in this way will it be possible to lessen the frequency of this disastrous event.

Anesthesia↗
PubMed1976

The effects of age on baroreceptor reflex function in man.

The relationship of age to baroreceptor reflex activity was determined in 35 healthy volunteers ranging in age from 19 to 65 years. Intra-arterial catheters were placed and blood pressure and pulse rate responses of each subject were observed during a Valsalva maneuver (31 subjects) and during the Pressor Test (33 subjects). The Valsalva maneuver consisted of a forced expiration sufficient to raise a column of mercury 40 torr for 10 seconds. This resulted in a reduction in pulse pressure (Baroreceptor stimulus) during the maneuver followed by a transient overshoot in diatolic pressure (response) following its termination. In comparison to younger subjects, older subjects had a greater reduction in pulse pressure but similar overshoot in diastolic pressure. The pressor test consisted of observing the effect of increasing systolic blood pressure (stimulus) on pulse duration (response) following the intravenous administration of phynylephrine. By relating each systolic pressure to the immediately succeeding R-R interval, a linear relationship was found. Its slope expressed in milliseconds of R-R interval change per torr increase in systolic pressure is an index of baroreflex function. Older subjects have less cardiac slowing compared to younger subjects and a hyperbolic relationship exists between age and slope (r = 0.84, p less than 0.05). These tests indicate that baroreceptor reflex function decreases with aging.

Adult↗