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Biomedical subjects

G Cassady

Publications and source records attributed to G Cassady.

At least 37 records · Page 2Linked to original sources
PubMed1985

Diuresis and natriuresis following acute pneumothorax in very low birthweight infants.

Seven tension pneumothoraces developed in six very low birthweight infants receiving assisted ventilation for hyaline membrane disease. Mean values for blood pressure and creatinine clearance (Ccr) tended to increase following pneumothorax decompression, although neither increase was statistically significant. Urine volume, osmolar clearance and urine sodium excretion all increased significantly in the 8 h following diagnosis and decompression of pneumothoraces. However, when expressed as a percentage of Ccr, none of these variables changed significantly. Mean sodium balance changed from positive to negative despite a significant increase in urine aldosterone excretion. It is suggested that the increases in osmolar clearance and sodium excretion were consequences of the increase in Ccr following pneumothorax decompression. Developmental immaturity in the renal tubular response to aldosterone might also have contributed to development of negative sodium balance.

Acute Disease↗
PubMed1985

Neonatal transcutaneous bilirubinometry.

The authors present data supporting the conclusion that the transcutaneous bilirubin index may be a valuable tool to help distinguish term babies with a total serum bilirubin value less than 13 mg/dl from those with higher levels and that it serves as a valuable screening device to decrease the number of unnecessary total serum bilirubin tests. Also examined are clinical guidelines and limitations of the device.

Bilirubin↗
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

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

Occupational risk for primary cytomegalovirus infection among pediatric health-care workers.

The risk of acquiring cytomegalovirus (CMV) from infected infants concerns pediatric health-care workers, particularly those who may be pregnant. We determined the prevalence of CMV antibody, and thus of past infection, in groups of medical students and house staff, nurses, and physicians, and in groups of pregnant and nonpregnant young women in the community. Although age, sex, and race influenced the results, occupation did not. We then estimated the exposure of the health-care workers by determining the prevalence of CMV infection in three groups of asymptomatic infants for whom they provided care; CMV was shed in urine or saliva of 1.6 per cent of newborns, 13 per cent of premature infants hospitalized for over a month, and 5 per cent of older infants seen in outpatient settings. When we determined the incidence of primary infection in the adult groups by retesting the seronegative members about two years later, we found that the annual attack rates in the medical students (0.6 per cent), house staff (2.7 per cent), and nurses (3.3 per cent) were not higher than in young women in the community (2.5 per cent during pregnancy and 5.5 per cent between pregnancies). We conclude that although pediatric health-care workers frequently and unknowingly care for infants shedding CMV, this occupational contact confers no greater risk than that faced by young women in the community at large.

Adult↗
PubMed1983

Systemic bacterial infections in neonatal deaths.

Bacterial were identified in 126 blood and CSF cultures obtained in 311 consecutive neonatal deaths (41%). These postmortem cultures were of diagnostic value, providing the sole means for definitive bacteriologic diagnosis in 82 (65%) of the 126 infected infants. Similarity of organisms found in specimens before and after death (identical in 25 of 26), similar identity of organisms identified by histologic Gram's stain and culture (the same in 48 of 49), and the identical nature of organisms identified from blood and CSF sites (the same in 43 of 43) support the validity of these cultures. Bacterial infection remains a serious problem in neonatal intensive care. The scope of this problem may be underestimated if postmortem cultures are not obtained.

Bacterial Infections↗
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↗
PubMed1983

Cardiac output and organ blood flow in young rabbits during intermittent positive-pressure ventilation.

Cardiac output and organ blood flow were measured by a microsphere technique in three groups of healthy young rabbits. In one group, animals were subjected to light sedation and intermittent positive-pressure ventilation. Control animals in a second group were sedated but not ventilated. In a third group, animals were conscious and breathing spontaneously. Cardiac output increased significantly (p less than 0.05) in conscious controls and in one measurement in anesthetized controls. It did not change in ventilated rabbits. Blood flow to the brain increased during study in all three groups and to the eye in both control groups. These elevations in cardiac output and cerebral blood flow were attributed to arousal. Blood flow to the kidney decreased in both anesthetized groups. The blood flow to skin, muscle, ileum and colon decreased significantly in the ventilated animals though not in the anesthetized controls. In both groups, similar reductions were found in the fractional distribution of cardiac output to these areas. It was concluded that ventilation at low pressure had no effect on cardiac output. The occurrence of redistribution of the circulation was deduced from the parallel reductions of regional blood flows and fractions of cardiac output received by some organs together with preservation of cerebral blood flow, though it was obscured in the two control groups by simultaneous increases in cardiac output. The circumstances suggested that this redistribution was due to disturbed homeostasis from arousal. Implications for the newborn were discussed.

Animals↗
PubMed1983

Colloid osmotic pressure at birth. Effect of sample site, type, and mode of delivery.

Colloid osmotic pressure was measured at birth in 102 newborns. Umbilical vein plasma colloid osmotic pressure correlated with total serum protein, birth weight, and gestational age. Mean colloid osmotic pressure of 11 infants who were small for gestational age was less than, and that of seven infants who were large for gestational age was more than, that of average-sized infants of similar gestation. For infants weighing 1,501 to 3,000 g, mean (+/- SD) colloid osmotic pressure following cesarean section (15.1 +/- 1.6 mm Hg) was lower than that following vaginal delivery (18.4 +/- 2.2 mm Hg). This may reflect the fact that use of maternal fluid therapy preceding cesarean section was greater than before vaginal delivery. The definition of normative values for neonatal plasma colloid osmotic pressure makes it possible to investigate changes in relation to disease, therapy, and subsequent outcome in sick neonates.

Birth Weight↗
PubMed1982

Radionuclide angiography in the evaluation of ductal shunts in preterm infants.

Radionuclide angiograms were compared with radiographic and physical findings and with echocardiographic left atrial to aortic ratios in 30 neonates clinically suspected of having a persistent ductus arteriosus. In three infants without clinical signs and with normal LA/Ao ratios (10%), radionuclide angiograms provided evidence of a large left-to-right shunt, which was confirmed by the finding of a large ducts arteriosus at surgery. Whereas routine physical, radiographic, and echocardiographic criteria fail to identify some neonates with large PDA's, the present study suggests that radionuclide angiography can be performed in a neonatal intensive care unit setting and may be a valuable addition to currently employed diagnostic techniques.

Angiography↗
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↗