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Biomedical subjects

J B Philips

Publications and source records attributed to J B Philips.

54 records · Page 3Linked to original sources
PubMed1985

Hemodynamic effects of nifedipine in normoxic and hypoxic newborn lambs.

We studied the effects of nifedipine, a calcium-channel blocker, in two acutely instrumented groups of newborn lambs during normoxic and hypoxic conditions. Nifedipine at 10 or more micrograms/kg reduced systemic, but not pulmonary artery pressure and resistance in normoxic lambs. When acute hypoxia was produced in these animals, 50 or more micrograms/kg reduced, but did not prevent, the expected rise in pulmonary pressure and resistance. When infused into already hypoxic lambs, nifedipine in doses of 50 micrograms/kg or more reduced both systemic and pulmonary pressures and resistances equally. Thus, nifedipine is a nonspecific vasodilator in newborn lambs.

Analysis of Variance↗
PubMed1984

Characteristics, mortality, and outcome of higher-birth weight infants who require intensive care.

The improved outcome of small infants who have received intensive care is well documented; however, the mortality and morbidity of infants weighing greater than or equal to 2500 gm who require intensive care have not been emphasized. During a 2-year period these infants accounted for 41% of admissions and 34% of all deaths in our nursery. The most common diagnoses were pulmonary disease (32%), asphyxia (22%), congenital anomalies (18%), infant of diabetic mother (10%), hematologic disease (9%), and infection (4%). Mortality was 11% with 50% of the deaths from lethal malformations, 26% from asphyxia, 13% from infection, and 11% from miscellaneous causes. One half of the deaths were potentially preventable. According to developmental follow-up, over 90% of the survivors were developing normally. Thus, while outcome for survivors is usually good, mortality remains excessively high. This large and understudied group of infants requires increased investigative emphasis.

Birth Weight↗
PubMed1984

Management of the depressed newborn.

The experienced obstetrician knows that depressed neonates do not always herald their coming, and that the potential liability for failure to intervene promptly is great. It is imperative that all personnel involved in the delivery and care of newborns be familiar with these principles of newborn resuscitation.

Acidosis↗
PubMed1984

Prostaglandins and related compounds in the perinatal pulmonary circulation.

It is clear that the products of arachidonate metabolism (prostaglandins, leukotrienes, thromboxanes, etc) are involved in both normal and pathophysiologic pulmonary vascular responses. However, the precise roles of these compounds in the various pulmonary vasoregulatory processes remain unclear. This paper reviews the synthetic pathways for these compounds and summarizes the current state of knowledge regarding their involvement in the perinatal pulmonary circulation. Data regarding endogenous compounds as well as the effects of exogenously administered agents are presented.

Animals↗
PubMed1984

Prostaglandins, related compounds, and the perinatal pulmonary circulation.

It is clear that prostaglandins and related compounds are important in the physiology and pathophysiology of the perinatal pulmonary circulation. This article focuses on what is known about prostaglandin-related compounds (PRC) in the pulmonary circulation of the developing and newly born mammal. Also included is a discussion of the effects of PRC on the ductus arteriosus and on the systemic circulation.

Animals↗
PubMed1984

Pharmacokinetics of cefoperazone in newborn infants.

We studied the disposition of two 100 mg/kg doses of cefoperazone given intravenously 12 hr apart in ten newborn infants. Peak levels were a mean 352 +/- SD 75 and 371 +/- 68 micrograms/ml immediately after the first and second dose, respectively, with corresponding troughs of 60 +/- 10 and 76 +/- 28 mcg/ml 12 hr later. Mean half-life was 6.5 +/- 0.9 hr and decreased with increasing gestational age and birthweight. Steady-state volume of distribution averaged 410 +/- 40 ml/kg and total clearance 0.78 +/- 0.13 ml/min X kg and neither varied with gestational age nor birthweight. No untoward physical or laboratory effects were noted. Additional studies including postnatal age effects on kinetics, efficacy, and cerebrospinal fluid penetrance are necessary prior to widespread use of this potentially valuable antibiotic in newborn infants.

Cefoperazone↗
PubMed1983

Prostaglandin D2 inhibits hypoxic pulmonary vasoconstriction in neonatal lambs.

Intrapulmonary injections of prostaglandin D2 (PGD2) reduce pulmonary arterial pressure and resistance in fetal and hypoxic neonatal lambs without affecting systemic arterial pressure. This apparently specific pulmonary effect of PGD2 could be explained by inactivation of the agent during passage through the pulmonary capillary bed. We therefore studied the effects of both pulmonary and systemic infusions of PGD2 on the acute vascular response to a 1-min episode of hypoxia in newborn lambs. Since PGD2 has been reported to be a pulmonary vasoconstrictor in normoxic lambs, we also evaluated its effects during normoxemia. Pulmonary vascular pressures were not affected by either 1- or 10-micrograms . kg-1 . min-1 infusions into the left atrium or inferior vena cava during normoxia. Infusion of 1 microgram . kg-1 . min-1 PGD2 into the inferior vena cava decreased pulmonary vascular resistance and increased systemic arterial pressure. These two parameters were unchanged with the other three infusion regimens. Mean pulmonary vascular resistance rose 83% with hypoxia and no PGD2. PGD2 prevented any change in pulmonary vascular resistance with hypoxia, while systemic arterial pressure increased (1-microgram . kg-1 . min-1 doses) or was unchanged. Thus PGD2 specifically prevents hypoxic pulmonary vasoconstriction while maintaining systemic pressures, regardless of infusion site. PGD2 may be indicated in treatment of persistent pulmonary hypertension of the newborn and other pulmonary hypertensive disorders.

Animals↗
PubMed1982

Recommended amikacin doses in newborns often produce excessive serum levels.

Emergence of a multiply drug resistant Enterobacter cloacae during a seven-week period in 1980 caused amikacin to become the aminoglycoside of choice in the initial management of suspected sepsis in a neonatal intensive care unit. Recommended doses (7.5-10 mg/kg loading; 15 mg/kg in two divided doses IV) were given to 5 infants < or = 1,000 gm and to 13 larger babies. Trough levels 11.5 hours after a dose were 16.6 +/- 11.9 microg/ml in infants < or = 1,000 gm and 6.5 +/- 4.3 microg/ml in the larger infants (P < 0.02). Peak levels one hour postinfusion exceeded 40 microg/ml in 3 of 5 < or = 1,000-gm babies and 4 of 12 > 1,000-gm infants (P = NS). Overall, 7 of 10 peak and/or trough levels in < or = 1,000-gm infants were in the range considered toxic in adults, versus 7 of 24 in larger babies (P = 0.03). These data show that surprisingly excessive blood levels of amikacin are likely in infants < or = 1,000 gm and may also occur in larger infants using currently recommended dosage schedules. These unexpected findings emphasize the need to monitor drug levels and individualize therapy in very low birthweight infants.

Amikacin↗
PubMed1980

Effect of positive end-expiratory pressure on dynamic respiratory compliance in neonates.

A simplified method of determining dynamic respiratory compliance (C dyn) in the newborn is described. Studies were performed during mechanical ventilation on 24 infants with respiratory distress syndrome (RDS) and 6 infants without RDS. Cdyn was evaluated at pressure settinghs of 20/0, 25/5 and 30/10 cm H2O. Significant decreases (p < 0.05) in Cdyn were noted with each increase in end-expiratory pressure setting. The values for Cdyn in RDS patients obtained by this method closely approximated previously published data for lung compliance in babies with RDS. This simple and reproducible method may be useful in following the course of illness in infants with RDS.

Forced Expiratory Flow Rates↗