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Biomedical subjects

K L Peters

Publications and source records attributed to K L Peters.

29 records · Page 2Linked to original sources
PubMed1989

Nasal intermittent positive-pressure ventilation offers no advantages over nasal continuous positive airway pressure in apnea of prematurity.

A prospective, randomized, cross-over trial was performed to compare the efficacy of nasal intermittent positive-pressure ventilation with nasal continuous positive airway pressure in infants of less than 32 weeks of gestation. Continuous positive airway pressure was delivered at end-expiratory pressures of 4 cm H2O, while peak pressures of 20 cm H2O and end-expiratory pressures of 4 cm H2O were used during nasal intermittent positive-pressure ventilation at ventilatory rates of 20 breaths per minute. The frequency and extent of apnea and bradycardia during a 6-hour period in a patient receiving nasal continuous positive airway pressure were compared with a similar crossover period of nasal intermittent positive-pressure ventilation. Although the infants had slightly less frequent episodes of apnea per hour (0.6 +/- 0.7 vs 0.5 +/- 0.7) and bradycardia per hour (1.2 +/- 1.3 vs 0.9 +/- 1.0) during nasal intermittent positive-pressure ventilation, these differences were not significant. There were no significant differences in the severity of these events as assessed by the duration and fall in transcutaneous oxygen pressure during apnea and heart rate during bradycardia. There were no significant changes in blood gases throughout the study. Nasal intermittent positive-pressure ventilation appears to have no advantages over nasal continuous positive airway pressure in preventing apnea and does not alter gas exchange in infants of less than 32 weeks of gestation.

Apnea↗
PubMed1986

Physiologic effects of doxapram in idiopathic apnea of prematurity.

Twelve premature infants with significant apnea of prematurity while receiving therapeutic doses of aminophylline were given an intravenous infusion of doxapram, 2 or 2.5 mg/kg/hr. The ventilatory effects of the medication were monitored by means of face mask spirometry and airway occlusion studies. Doxapram therapy was associated with significant increases in minute ventilation, tidal volume, mean inspiratory flow, and airway pressure 100 msec after occlusion. Respiratory frequency and the relative duration of inspiration and expiration were unchanged. Paco2 decreased significantly during the infusion. The apnea attack rate, monitored by continuous recording, was significantly reduced after the first 6 hours of therapy. Six hours after starting doxapram, mean arterial blood pressure was significantly elevated, and continued to increase during the 24 hours of therapy. Doxapram is effective in treatment of apnea of prematurity refractory to aminophylline, and appears to act by increasing respiratory center output.

Aminophylline↗
PubMed1986

Limitations of self-inflating resuscitators.

In an effort to characterize the performance of self-inflating resuscitators, three examples of three models were subjected to laboratory testing: the Ohio Hope II resuscitator (Ohio Medical Products, Madison, WI), the PMR-2 resuscitator (Puritan Medical Products, Lenexa, KS), and the Laerdal resuscitator (AS Laerdal, Stavanger, Norway). The devices were connected to a test lung and compressed at frequencies of from 10 to 60 and at greater than 60 breaths per minute at 5, 10, and 15 L/min of flow. These devices were used with and without a reservoir and were compressed at less than and more than the pop-off valve pressures. The results revealed that all devices equipped with reservoirs delivered a significantly higher oxygen concentration than those without (P less than .001), and that activation of the pop-off valve significantly reduced Fio2 under all conditions (P less than .005). The pop-off valves for each device were activated throughout a wide range of pressures, the Laerdal 41 to 72 cm H2O, PMR-2 51 to 97 cm H2O, and the Ohio Hope II 38 to 106 cm H2O, well in excess of the manufacturer's specifications. Only the Laerdal with reservoir was able to deliver an Fio2 of greater than 0.9 when compressed at more than the pop-off valve pressure at rates of up to 30 breaths per minute using flows of 10 L/min, and it was the only device to produce Fio2 values of greater than 0.9 at all rates to 60 breaths per minute when compressed at less than the pop-off valve pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗
PubMed1984

An evaluation of theophylline for idiopathic apnea of infancy.

19 infants admitted with a diagnosis of infantile apnea who were found to have periodic breathing were given oral theophylline to determine its effect. They were studied at a mean age of 7.1 weeks (1-16.4 week). Each infant was studied during two naps, immediately before and 7 days following the institution of theophylline therapy, which averaged 2.8 h in duration during which electro-oculograms, end-tidal CO2, heart rate, impedance respirations, and transcutaneous pO2 (tcpO2) were continuously monitored. Theophylline therapy (mean dose 2.3 mg/kg q. 6 h) was associated with a significant reduction of apnea attack rates in both REM and non-REM sleep. Periodic breathing and the number of minutes per hour of sleep during which the TC pO2 was between 40-50 mm Hg in non-REM sleep also decreased. There was no significant reduction in the number of obstructive apneas, the number of bradycardias with apnea, nor the largest single fall in tcpO2. Theophylline can significantly reduce central apnea and periodicity in the age group studied, but the long-term effects of such therapy require further assessment.

Apnea↗
PubMed1984

Vitamin E and necrotizing enterocolitis.

Although vitamin E has been shown to reduce the incidence of severe sequelae from retrolental fibroplasia, there have been recent suggestions that its use may be associated with an increased incidence of necrotizing enterocolitis (NEC). A review was made of experience with vitamin E, both intramuscular and oral, and NEC over a 4 1/2-year period. Of 418 infants of birth weight less than 1,500 g admitted during this period, 28/209 infants who had received vitamin E had definite NEC (13.4%) compared with 12/209 who had not received vitamin E (5.74%, chi 2 = 7.07, P = .008). For infants of birth weight less than 1,250 g, 16/103 infants who received vitamin E developed NEC v 1/159 who had not (chi 2 = 21.1, P less than .001); the incidence of NEC was not significantly different between the two groups for infants with birth weight between 1,250 to 1,500 g. The early mortality (less than seven days) for infants with birth weight of 1,500 g or less was significantly greater for those who had not received vitamin E (43.5% v 13.8%, chi 2 = 44.9, P less than .001), most probably a reflection of the omission of this drug for the most critically ill infants in this retrospective review. The incidence of NEC was not different for infants with birth weight of 1,500 g or less who received intramuscular vitamin E compared with control infants from the same period. For those infants for whom serum tocopherol levels were available, no infant who developed NEC and who had received only oral vitamin E had a serum tocopherol levels of greater than 3.5 mg/100 mL.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1983

Factors affecting outcome in hypoxic-ischemic encephalopathy in term infants.

Forty-nine term infants were prospectively shown to have hypoxic-ischemic encephalopathy (HIE). All infants survived the neonatal period, and all but two infants (seen at 12 months) were followed up to at least 27 months of age. Factors that significantly correlated with outcome included the Sarnat encephalopathy stage and the occurrence of intractable seizures not controlled by phenobarbital sodium alone. There was no association between the one- or five-minute Apgar score, the need for early ventilation, the EEG, the occurrence of seizures, and the subsequent outcome. There was no significant difference in outcome for those infants who received dexamethasone sodium phosphate (n = 29) v those who did not receive the drug (n = 20). A review of 97 term infants with HIE from a regional perinatal program during a one-year period (1979), including 35 of the 49 infants in the present study, did show a significant increase in morbidity and mortality for transported infants.

Adolescent↗
PubMed1983

Vitamin E and retrolental fibroplasia: prevention of serious ocular sequelae.

In an attempt to determine the role of vitamin E in retrolental fibroplasia (RLF) we report our experience with 191 infants of less than 1500 g birth weight. Of these infants, 16.75% had evidence of acute RLF in hospital, 8.4% had cicatricial RLF at follow-up, and four infants (2.1%) were blind, none of whom had received supplementary vitamin E. The incidence of cicatricial RLF at follow-up was significantly lower in infants who received vitamin E early after birth (12 h) than in those who did not (3 of 105 versus 13 of 86, X2 = 9.26, P = 0.002), as was the incidence of Grade III or greater cicatrix (0 of 105 versus 7 of 86, X2 with Yates = 6.72, P = 0.01). Stepwise multiple linear regression analysis revealed three factors distinguishing infants who developed cicatricial RLF from those who did not: the lack of early vitamin E supplements (P = 0.0023), the significantly larger number of arterial PO2 values over 100 mmHg (P = 0.0056), and the presence of an intraventricular haemorrhage (P = 0.0032). The incidence and severity of necrotizing enterocolitis was similar in infants who received vitamin E and in those who did not. It is recommended that vitamin E be given within the first 12 hours of birth to all infants of less than 1500 g who require supplementary oxygen.

Administration, Oral↗
PubMed1981

Hypoxic-ischemic encephalopathy in term neonates: perinatal factors and outcome.

Ninety-five infants of 37 weeks' gestation or greater with evidence of hypoxic-ischemic encephalopathy following perinatal asphyxia were prospectively identified in the neonatal period. The degree of encephalopathy was graded the staging system of Sarnat and Sarnat. Six infants died, 78 infants were sequentially followed in the Neonatal Follow-up Clinic, and in five additional infants, follow-up information was available. The mean duration of follow-up was 19.3 months. Fifty-eight (65%) of the 89 infants followed were normal or mildly handicapped, six (7%) died, and the remainder had significant handicap. There was no significant relationship between any of over 100 obstetrical antepartum or intrapartum variables and outcome. Infants with five-minute Apgar scores of 0 to 3, seizures within the first day of life, Stage II or III encephalopathy, or a suppressed electroencephalogram had a significantly greater incidence of severe handicap or death. In addition, although there were fewer females, they had a significantly greater incidence of handicap. There appeared to be an improved outcome in the last two years (1977-1978) compared to the first two years (1975-1976), suggesting that improved recognition and neonatal management may lead to a decrease in significant sequelae.

Apgar Score↗
PubMed1981

Effects of alterations of inspiratory and expiratory pressures and inspiratory/expiratory ratios on mean airway pressure, blood gases, and intracranial pressure.

Twenty neonates requiring mechanical ventilation for respiratory failure, including 13 with hyaline membrane disease, were studied to assess the effects of alterations in ventilator settings on mean airway pressure (MAP), blood gases, and intracranial pressure (ICP). The study involved random alterations in peak inspiratory pressure (PIP), positive end-expiratory pressure (PEEP), and inspiratory/expiratory ratio while MAP, PaO2, ICP, and end-tibal PCO2 were continuously monitored. The results showed a significant relationship between MAP and PaO2 that was expressed as the change in PaO2 per millimeter of mercury change in MAP (delta PaO2/delta MAP) with a mean delta PaO2/delta MAP of 4.92. The delta PaO2/delta MAP was highest for changes in PEEP (6.08), followed by PIP (5.07), and inspiratory/expiratory ratio (1.9). There was a significant relationship between alterations in PEEP and PIP vs PaCO2 and pH. Increases in PEEP and decreases in PIP resulted in an elevated PaCO2 and a lowered pH, and decreases in PEEP and increases in PIP resulted in a decreased PaCO2 and an elevated pH. There was no significant relationship between MAP and ICP, but there was a significant association between delta ICP and delta PaCO2 during alterations in PIP (r = .64, P less than .001). Increases in PEEP will lead to the greatest increase in PaO2 per change in MAP, followed by increase in PIP and inspiratory/expiratory ratio using a pressure-limited ventilator.

Airway Resistance↗
PubMedDate not supplied

Outcome of shunted posthemorrhagic hydrocephalus in premature infants.

Patient histories of 29 infants were reviewed whose birth weights were less than 2,000 gm and who had received ventricular shunts in the neonatal period for posthemorrhagic hydrocephalus. This procedure was performed at a time when routine screening of low birth weight infants for intracranial hemorrhage was not undertaken and serial lumbar puncture usually was not employed. The overall outcome was poor, with 62% of shunted infants either dying or surviving with moderate or severe handicap. Neurodevelopmental outcome was associated with the interval between the diagnosis of hydrocephalus and shunting; an adverse outcome was associated with an increased interval. Current practices for treating posthemorrhagic hydrocephalus are discussed.

Birth Weight↗