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Biomedical subjects

R Baldwin

Publications and source records attributed to R Baldwin.

At least 19 recordsLinked to original sources
PubMed1992

Delayed compliance increase in infants with respiratory distress syndrome following synthetic surfactant.

Recent research has demonstrated that Exosurf (EXSF), a newly synthesized artificial surfactant, increases survival when administered endotracheally to premature infants with RDS. This study examines the effects of EXSF on static respiratory system compliance (Crs). Thirty-four patients received two doses of EXSF in this rescue protocol. Crs (mL/cmH2O/kg) did not significantly change within the first 4 hours after either dose. However, Crs values did increase significantly (paired Student's t-test, P = 0.005) when data collected after the second dose (0.36 +/- 0.13 mL/cmH2O/kg) were compared to first week follow-up data (0.51 +/- 0.21 mL/cmH2O/kg). Crs data collected between 2 and 4 weeks after treatments were again not significantly different from non-concurrent control data collected at 3-4 weeks of life. The measurement of Crs in infants receiving EXSF may have been affected by an increase in lung inflation, which could mask an increase in Crs. We speculate that improved lung inflation may occur with less barotrauma in the first week of life due to surfactant replacement treatment and may in part explain the improved Crs seen at 1 week of age. Many investigators using different surfactants, dosing schedules, and pulmonary function methodologies to evaluate lung mechanics have reported that the improvement in compliance after surfactant treatment usually follows the clinical improvement in gas exchange. Additional studies are needed to explain the mechanism of early improvement following surfactant replacement in infants with RDS.

Drug Combinations↗
PubMed1991

SPECT imaging of the benzodiazepine receptor in non-human primate brain with [123I]Ro 16-0154.

We have used SPECT (single photon emission computed tomography) imaging in non-human primates to examine the time course and pharmacological specificity of 123I-labeled Ro 16-0154 as an in vivo probe of the benzodiazepine receptor. Maximal brain uptake was reached approximately 70 min post i.v. administration of the radioligand and represented approximately 10% of the injected dose. The regional distribution of radioactive densities was consistent with the known distribution of benzodiazepine receptors in primate brain, with highest uptake localized over the occipital area. Washout of radioactivity was relatively slow with a rate of 3% per hour after the time of peak radioactivity. Injection of the benzodiazepine antagonist Ro 15-1788 (0.2-0.3 mg/kg i.v.) caused a rapid decrease of more than 90% of radioactivity from brain. In summary, [123I]Ro 16-0154 is a promising in vivo SPECT radioligand for the benzodiazepine receptor, with high brain uptake, a stable period of peak radioactivity, appropriate regional distribution, and ability to be displaced by other benzodiazepine receptor agents.

Animals↗
PubMed1988

Nocturnal asthma: snoring, small pharynx and nasal CPAP.

We studied two populations of patients who snored and had frequent nocturnal asthma attacks: ten overweight men presenting with typical obstructive sleep apnoea syndrome, and a group of five adolescents with regular snoring and an increase in negative inspiratory oesophageal pressure during stage II non-rapid eye movement (NREM) and rapid eye movement (REM) sleep. All subjects presented cranio-mandibular abnormalities at cephalometric evaluation, with a narrow space behind the base of the tongue. Both populations were treated with nasal continuous positive airway pressure (CPAP) during sleep. Snoring and partial or complete airway obstruction were eliminated, as were the nocturnal asthma attacks. Two adolescents treated with upper airway surgery after nasal CPAP showed no nocturnal asthma at short-term follow-up. Nasal CPAP had no effect on daytime asthma. One hypothesis is that a subgroup of asthmatic patients with small pharynxes may have enhanced vagal stimulation during sleep compared with other asthmatic patients. This enhancement would be related to the repetitive Müller manoeuvres noted with airway obstruction during sleep. Combined with the local effects of snoring, this extra vagal stimulation would be a precipitating factor in nocturnal asthma attacks.

Adolescent↗
PubMed1986

Alternative treatment to tracheostomy in obstructive sleep apnea syndrome: nasal continuous positive airway pressure in young children.

Two groups of prepubertal children with severe obstructive sleep apnea syndrome received continuous positive airway pressure (CPAP) treatment using a nasal mask. The five children in group A had nasal CPAP only in a hospital setting; the five children in group B received the treatment at home as well. Four of these five children, who have now been followed for as long as 10 months, have adapted well to the treatment at home. The problems encountered with nasal CPAP as a home treatment, such as poor cooperation from parents, allergic rashes, eye irritation resulting from air leaks, are discussed. Despite the problems, nasal CPAP is a valid alternative to tracheostomy in children as young as 3 years of age.

Child↗
PubMed1986

Portasystemic shunt fraction quantification with colonic iodine-123 iodoamphetamine.

Portasystemic shunting was quantified in dogs with [123I]iodoamphetamine (IMP) administered transrectally into the colon and monitored externally with a gamma camera. IMP was absorbed rapidly and unchanged from the colon. After direct injection into the portal vein, IMP was almost completely extracted by the liver on the first pass, and the washout half-life was approximately 60 min. Based on these kinetic data, computer simulation of this biologic system was carried out. Errors associated with simplified models are calculated. The simplest model with insignificant error, which assumed that the tracer behaved like microspheres, was used to quantitate portasystemic shunt fraction in animals with surgically created shunts. Results were compared with the standard of 99mTc-labeled macroaggregated albumin infused into a branch of inferior mesenteric vein. For shunt fractions ranging from 0 to 100%, an excellent correlation was seen, indicating that this approach is potentially a simple, noninvasive method of portasystemic shunt fraction quantification.

Amphetamines↗
PubMed1985

Near-miss sudden infant death syndrome in eight infants with sleep apnea-related cardiac arrhythmias.

Eight full-term infants between 3 and 8 weeks of age, who had had 24 to 48 hours of vague problems involving a congested upper airway and/or irritability, had a life-threatening respiratory episode at home, called a near-miss for sudden infant death syndrome event. Polygraphically monitored mixed apneas occurred in clusters during non-rapid eye movement (NREM) sleep with significant cardiac arrhythmias, predominantly sinus arrest. The cardiorespiratory problems continued during sleep in the following 8 to 12 weeks but did not recur after that time, and there were no long-term sequelae when the children were studied again 4 to 7 years later.

Arrhythmias, Cardiac↗
PubMed1984

Evaluation of professional nursing practices in a community hospital cancer program: the methodology.

In summary, this evaluation plan is designed to assess current oncology nursing practices in a community setting. The focus of the plan is on patient problems identified in the CHCP Cancer Nursing Guidelines and the Hospice Nursing Guidelines. Critical decisions regarding which patient problems to focus on and the implementation of the evaluation plan remain with the CHCP committees. Technical assistance is provided by a CHCP Evaluation Specialist. Finally, summary reports will be generated at regular intervals so as to maximize the impact on current program development. There are several implications for this nursing evaluation plan, both immediate and long range. In the immediate, we hope that the results will help CHCP committees and individual hospitals make informed decisions about future program development. More importantly perhaps, we are for the first time in our local community identifying services central to nursing and developing base line data on the frequency of the delivery of these services. Looking into the future, we see additional implications for these studies. Currently, our evaluation system is a paper system, and paper systems are by their very nature time consuming and somewhat awkward. It is our hope that in the future information about nursing services will be registered on a computerized information system. Then, reports about the types of nursing services and amount of time spend with cancer patients could be automatically generated on a weekly basis, if so desired. However, if we are to attain this goal, we need to systematically identify common patient problems central to oncology nursing care that can be documented and studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Hospitals, Community↗
PubMed1983

'Near-miss' for sudden infant death syndrome infants: a clinical problem.

Three hundred six infants were referred for evaluation of "near-miss" sudden infant death syndrome (SIDS) from 1973 to 1980. Following the hospitalization and medical evaluation, there were 156 infants (115 term and 41 preterm) for whom there was no explanation for the presenting event and who were considered near-miss infants; 88% of these infants were seen during the first 3 months of life. A repeat near-miss event was reported in 63% (term) and 83% (preterm) infants. Twelve percent of term infants and 17% of the preterm infants had ten or more repeat events. A home apnea/cardiac monitor was prescribed for 88% of the infants for an average duration of 5.6 months in term infants and 3.5 months in preterm infants. Monitoring had been discontinued in 69% of the infants by 7 months of age. One full-term infant was later a SIDS victim. The risk of a repeat near-miss event is concluded to be sufficiently great to demand immediate hospitalization, medical evaluation, home monitoring when there is no specific treatment, and close clinical follow-up. Follow-up studies are needed to determine whether there is any long-term morbidity for infants who have had near miss events.

Age Factors↗
PubMed1982

Movement and gastroesophageal reflux in awake term infants with "near miss" SIDS, unrelated to apnea.

Forty-five term infants who had a "near miss" for SIDS were studied with a continuous overnight polygraphic recording of endoesophageal pH, respiration, and ECG. Recordings were examined for occurrences of GER and for central apnea of 10 seconds or greater duration. There were 341 apneic events greater than or equal to 10 seconds recorded in 46 studies, with a mean of 7 +/- 7. In 91% of the infants, no apneas exceeded 15 seconds. Only 31 episodes of apnea greater than or equal to 10 seconds occurred during GER: in two of these episodes the apneic event was greater than or equal to 15 seconds. Twenty-four of the 31 apneas greater than or equal to 10 seconds during periods of pH less than 4 occurred in one infant. A total of 356 precipitous pH drops was recorded (mean 8.7 +/- 7.4). The pH drops occurred most frequently when the patient appeared to be awake (73%), and in 84% of events there was movement before and during the pH change. We conclude that the majority of these near miss SIDS infants had GER associated with movement during awake periods, without any temporal relationship to apnea. Although reflex apnea following GER may be seen in some term infants, this problem may be more significant for the immature infant.

Apnea↗
PubMed1979

Mixed and obstructive sleep apnea and near miss for sudden infant death syndrome: 2. Comparison of near miss and normal control infants by age.

Twenty-nine full-term near miss for sudden infant death syndrome (SIDS) and 30 normal control infants underwent 24-hour polygraphic monitoring. Several types of respiratory events during sleep (eg, central, mixed, and obstructive apnea, periodic breathing) were defined and tabulated. Analysis of these respiratory variables and comparison of groups of near miss and control infants indicated that between 3 weeks and 4 1/2 months of age only one variable was consistently different at a statistically significant level: the number of mixed and obstructive apnea greater than 3 seconds during total sleep time. This study also showed an increase in mixed and obstructive respiratory events during sleep at 6 weeks of age in control as well as in near miss infants.

Female↗
PubMed1979

Obstructive sleep apnea and near miss for SIDS: I. Report of an infant with sudden death.

An infant girl followed up from birth to death at the University Medical Center had ""congenital stridor'' and a ""near miss for SIDS'' event at 3 months of age. As part of an ongoing SIDS research project, she underwent 24-hour polygraphic monitoring at 21 weeks of age. Sudden infant death occurred within 30 hours after the polygraphic study. Polygraphic data obtained from this infant are compared with those from control infants and other infants with near miss for SIDS who were of similar ages. The number of mixed and obstructive respiratory events during sleep was abnormally high on the infant's recording. Histologic findings, involving particularly the midline structures of the brain stem, are discussed.

Apnea↗
PubMed1976

The effects of neurally active amino acids on pituitary gonadotropin secretion.

Several neurally excitant amino acids were injected into the third ventricle of anesthetized male rats, and plasma levels of luteinizing hormone (LH) and follicle stimulating hormone (FSH) were measured. LH levels increased following injections of 2.0 mum glutamate, lysine, or beta-alanine. Glycine (2.0 mum), alpha-alanine (2.0 mum), and 0.9% saline were ineffective in altering LH levels. None of the amino acids tested significantly altered FSH levels. Of the 3 amino acids which raised blood LH levels following an intraventricular injection, i.e., glutamate, beta-alanine, and lysine, only lysine caused a significant increase in LH levels following injection into the pituitary. The present study provides evidence for a possible role for certain neurally excitant amino acids in the neuronal control of LH secretion.

Alanine↗