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Biomedical subjects

W W Fox

Publications and source records attributed to W W Fox.

At least 73 records · Page 4Linked to original sources
PubMed1980

Decreased oxygenation and hyperlipemia during intravenous fat infusions in premature infants.

Eighteen appropriate-for-gestational-age premature infants with birth weights ranging from 0.77 to 1.89 kg received 1 gm/kg of body weight of fat emulsion, intravenously, over a four-hour period. Infants less than 1 week of age developed a significant decrease in PO2 levels (P < 5.0) during the fat infusion period. There were no changes in other pulmonary function parameters. Infants less than 1 week of age also developed significantly higher peak levels of plasma triglycerides than infants 2 to 3 weeks old (P < .05). A correlation between increment in triglyceride levels and postnatal age was demonstrated (r = .75), with the younger infants presenting the higher triglyceride levels. This study demonstrates that: (1) small premature infants receiving intravenous fat are more susceptible to hyperlipemia and hypoxemia during the first week of life; (2) hypoxemia associated with intravenous fat infusion does not result from changes in lung dynamics; (3) the capacity to tolerate intravenous fats is enhanced after the first week of life.

Age Factors↗
PubMed1979

Epidemic occurrence of neonatal necrotizing enterocolitis.

In case-control studies of three epidemics of neonatal necrotizing enterocolitis (NEC) in three different high-risk nurseries in three states, no particular risk factor was associated with affected infants or their mothers. Epidemic cases had higher birth weights and Apgar scores and fewer perinatal difficulties than those previously reported for sporadic cases. Seven infants fed primarily breast milk were not protected against disease. Early antibiotic therapy was associated with a significantly decreased risk of disease in one outbreak. In two hospitals, affected infants who received antibiotic therapy during the first three days of life had a significantly later disease onset. The occurrence of the disease in epidemics and the decreased risk or modification of disease with antibiotic therapy support an infectious etiology for NEC.

Ampicillin↗
PubMed1979

Improved oxygenation and lung compliance with prone positioning of neonates.

Fourteen intubated infants recovering from neonatal respiratory disease had arterial blood gases and lung mechanics measured in the supine position and in two variants of the prone position. Prone positioning resulted in significant increases in mean (+/- SEM) arterial oxygen tension (Pa(o2 70.4 +/- 2.5 to 81.1 +/- 4.4mm Hg), dynamic lung compliance (1.7 +/- 0.24 to 2.55 +/- 0.37 ml/cm H2O),and tidal volume (8.6 +/- 1.0 to 10.5 +/- 1.2 ml) when all prone values were compared to supine values. Prone positioning with the abdomen protruding freely, when compared to all supine values, was associated with significantly increased dynamic lung compliance and tidal volume. Values for prone-abdomen free were not significantly different from values for prone-abdomen restricted. This suggests that there are clinical benefits from prone positioning in neonates recovering from respiratory disease.

Acid-Base Equilibrium↗
PubMed1979

Effects of endotracheal tube leaks on functional residual capacity determination in intubated neonates.

The present study evaluates a new closed circuit helium (He) dilution technique for determination of endotracheal (ET) tube leakage and functional residual capacity (FRC) in neonates with ET tubes. By analytically relating the fall in He concentration due to mixing with that due to leakage, it is possible to predict the final equilibration concentration of He and, therefore, correct for ET tube leaks. The system (120 ml) contains an air pump, He meter, breathing bag in cyclinder, a strip chart readout, and solenoid valve. Continuous positive airway pressure (CPAP) or ventilator pressure can be applied during testing. FRC measurements were performed on 13 neonates (799--4500 g) on CPAP with ET tubes. Leak rates were significantly higher (P less than 0.001) on 3 cm H2O CPAP compared to O cm H2O CPAP. The mean measured FRC was 53.5 ml at 3 cm H2O and 46.3 ml at 0 cm H2O CPAP. If gas leakage had not been considered in FRC calculations, the error in FRC could have been as high as 39% at 3 cm H2O CPAP and 18% at 0 cm H2O CPAP.

Birth Weight↗
PubMed1979

Cardiopulmonary changes in the crying neonate.

To determine hemodynamic effects of crying, 12 newborn infants recovering from the respiratory distress syndrome (RDS) were studied. When crying, the range of inspiratory esophageal pressure was -18.8 to -32.5 cm H2O and the range of espiratory pressure was +6.2 to 34.4 cm H2O. The esophageal pressure remained positive for a mean value of 66% of the respiratory cycle. There was a mean significant increase in heart rate of 19 beats/min. The systolic and diastolic blood pressures increased significantly at the beginning of strain to 115 and 135% of the respective control values. There was a progressive decrease in systolic and diastolic pressures during the period of strain and the systolic pressures reached values significantly less than control. With the decrease in systolic and diastolic pressures, there were pronounced reductions in pulse pressures. Three infants reached pulse pressure values less than 1% of control when cries were sustained for nine cardiac cycles. There was a significant mean decrease in arterial oxygen tension (PaO2) of 16.8 mm Hg. There were no changes in arterial carbon dioxide tension (PaCO2), pH, or base excess.

Blood Pressure↗
PubMed1979

A new device for diagnosis and treatment of neonatal pneumothorax.

A new closed-system device for the diagnosis and treatment of pneumothorax was evaluated in ten New Zealand white rabbits and compared with and open-system needle. The closed-system device proved to be safe for diagnostic thoracentesis. There were no pneumothoraces as a result of the procedure with the closed-system device as confirmed by chest roentgenograms and pleural pressure measurements. In contrast, 70% of the diagnostic thoracenteses with the open-system needle were associated with pneumothorax documented by x-ray films and a significant increase in mean pleural pressure. The new apparatus was more efficacious for evacuation of pneumothoraces because complete air removal occurred in 90% of the rabbits as compared with 60% of trials with the open-system needle. If the efficacy of the new closed-system device proves to be good in human infants, the pediatrician encountering a tension pneumothorax in the newborn can use a completely assembled system that is safe for diagnosing and treating this acute life-threatening condition.

Animals↗
PubMed1978

Pulmonary physiotherapy in neonates: physiologic changes and respiratory management.

To investigate physiologic alterations in respiratory function associated with chest physiotherapy, arterial blood gases, respiratory patterns, lung mechanics, and functional residual capacity were measured in 13 neonates (weights 1.25 to 3.20 kg) during the control period, after vibration of the chest and suctioning, after hyperventilation, and two hours after suctioning. Compared to control values, mean PO2decreased significantly after suctioning to 43 mm Hg and increased significantly after hyperventilation to 78 mm Hg. There was a significant decrease in inspiratory resistance and a trend toward decrease in expiratory resistance after suctioning, with return to control levels after hyperventilation. Respiratory rate increased significantly after suctioning. Functional residual capacity, dynamic lung compliance, and tidal volume, as well as PCO2 and base excess, were not changed appreciably throughout the protocol. Because of potentially severe hypoxemia, this study suggests that suctioning and hyperventilation are not warranted on a routine basis in infants recovering from respiratory diseases.

Carbon Dioxide↗
PubMed1978

Physiologic factors affecting pulmonary artery pressure in infants with persistent pulmonary hypertension.

Indwelling pulmonary artery catheters were used for continuous monitoring of pulmonary artery pressure in ten infants with severe persistent pulmonary hypertention of the newborn. The labile nature of pulmonary artery pressure, with changes up to 50 mm Hg, was documented. Pulmonary artery pressure in the eight infants with suprasystemic pulmonary hypertension was analyzed at the time of maximum decrease in pressure (mean 36.1 mm Hg) and physiologic measurements were compared over an eight-hour period. During the study period when the infants were hyperventilated, as the Paco2 decreased from 48.9 to 28.3 mm Hg (P less than 0.02) the mean pulmonary artery pressure decreased by 36 mm Hg (P less than 0.001) to subsystemic pressure levels, and the mean AadeltaO2 decreased by 146 mm Hg (P less than 0.001). After the decrease in pulmonary artery pressure, patients were mechanically ventilated to maintain Paco2 in the range of 25 to 30 mm Hg until pulmonary hypertension gradually resolved in the six survivors.

Blood Pressure↗
PubMed1977

The effects of feeding on arterial blood gases and lung mechanics in newborn infants recovering from respiratory disease.

Fifteen infants recovering from neonatal respiratory disease had arterial blood gases and lung mechanics measured 5 minutes before bolus feeds and at 5, 10, 20, and 30 minutes after feeding to determine physiologic effects of feeding. PaO2 fell significantly from prefeeding values at 5, 10, and 20 minutes after feeds. Mean prefeeding pH and base excess values were significantly different from mean postfeeding values at 5, 10, 20, and 30 minutes, respectively. PaCO2 remained unchanged before and after feeding. Heart rate and systolic and diastolic blood pressure did not change throughout the study. Dynamic lung compliance, respiratory, rate, and tidal volume did not change significantly but there was a trend toward increase in tidal volume. Mean minute volume rose with time as a consequence of the increased tidal volume. Work of breathing remained unchanged at 10 and 20 minutes postfeed and increased slightly at 30 minutes; this was due to a small increase in both elastic and viscous work components at this time.

Carbon Dioxide↗
PubMed1977

The clinical profile of the newborn with persistent pulmonary hypertension. Observations in 19 affected neonates.

In 19 neonates with severe cyanosis, normal chest x-rays, anatomically normal hearts, and a high incidence of perinatal complications, the clinical course was characterized by variable sustained cyanosis. Cardiac catheterization data showed high systemic or suprasystemic pulmonary artery pressure with right to left intracardiac shunting via the foramen ovale and ductus arteriosus. Arterial oxygen tension at an inspired oxygen concentration above 65% was helpful in distinguishing these patients from those with congenital heart disease, and for predicting prognosis.

Blood Pressure↗
PubMed1977

Tracheal extubation of the neonate at 2 to 3 cm H2O continuous positive airway pressure.

To investigate the efficacy of extubation at higher levels of continuous positive airway pressure (CPAP), 49 newborns (0.95 to 4.0 kg) were extubated at 2 to 3 cm H2O following 1 to 47 days of CPAP therapy. Pre- and postextubation measurements of Po2, PCO2, pH, FiO2, and CPAP were made in all infants. No significant differences (P less than.05) were found between pre- and post-extubation arterial blood gas values for all patients. Comparison of pre- and post-extubation blood gas data with respect to birthweight (less than 2.0 kg vs greater than 2.0 kg) and intubation time (less than 8 days vs. greater than 8 days) also indicated no statistical differences. Mean alveolar-arterial oxygen differences and FiO2 for 41 infants showed progressive decreases following extubation. Six of the 49 infants required reintubation within 72 hours following extubation. The results of this study indicate that newborns with respiratory disease requiring CPAP may be extubated at 2 to 3 cm H2O with no significant changes in arterial blood gas values, thus preventing prolonged intubation associated with weaning to 0 cm H2O CPAP.

Birth Weight↗
PubMed1977

Pulmonary hypertension in the perinatal aspiration syndromes.

Ten patients clinically diagnosed as having perinatal aspiration syndromes were found to have pulmonary hypertension. These infants were either term or postmature babies and had the following characteristics: (1) systemic or suprasystemic levels of pulmonary artery pressure (range, 50 to 117 mm Hg); (2) a degree of pulmonary hypertension not related to the degree of aspiration evident on chest roentgenograms; (3) evidence of right-to-left shunting at the ductal or foramen ovale level; and (4) sustained severe hypoxemia despite 100% inspired oxygen concentration. The overall mortality for the group was 50%. Since these patients had marked clinical and physiologic similarities to patients previously reported as having the persistent fetal circulation syndrome (PFC), they were classified as having "PFC with aspiration." The existence of pulmonary hypertension should be suspected despite roentgenographic evidence of aspiration in any patient who also manifests the clinical characteristics of PFC because its treatment may alter the prognosis of such patients.

Birth Weight↗