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Biomedical subjects

A R Spitzer

Publications and source records attributed to A R Spitzer.

89 records · Page 5Linked to original sources
PubMed1986

Inductive plethysmography--a facilitated postural calibration technique for rapid and accurate tidal volume determination in low birth weight premature newborns.

Inductive plethysmography is a noninvasive method of measuring lung volumes in infants. This technique, however, has had very limited use in premature newborns because of the difficulty of calibrating the device with regard to the small tidal volumes (VT) in such infants. The present study describes a facilitated calibration of the inductive plethysmograph in low birth weight infants. The technique depends on generating significantly different compartmentalization of VT into rib cage and abdominal components by changing the infant's position from supine to upright. Linear regression analyses were performed to compare VT measurements made in 9 premature infants with the inductive plethysmograph and the pneumotachygraph; an overall Z-transformed correlation of 501 breath-to-breath comparisons yielded an r value of 0.80; the mean VT (pneumotachygraph) was 13.9 +/- 4.7 ml SD; the mean VT (inductive plethysmograph) was 14.3 +/- 5.1 ml SD. It is concluded that inductive plethysmography is an accurate method to measure VT in small premature infants. Moreover, the ease of the two-position technique for calibration of the device gives the inductive plethysmograph greater utility as a clinical and research tool for measuring lung volumes in premature infants.

Calibration↗
PubMed1985

Cerebral cortical function in infants at risk for sudden infant death syndrome.

Cerebral cortical function was prospectively examined by electroencephalography (EEG) in 3 subgroups of 257 infants at risk for sudden infant death syndrome (SIDS). Group 1 consisted of apparently healthy infants with near-miss SIDS episodes; Group 2 consisted of siblings of SIDS victims; and Group 3 consisted of neurologically suspect infants with apnea. The usual abundance and distribution of sharp EEG transients (SETs) were determined from 69 Group 1 infants. EEGs were interpreted as abnormal in the presence of ictal apnea, excessively abundant SETs, or immaturity of EEG background for conceptional age. Ninety percent of infants in Group 1 had entirely normal EEGs. There was no significant difference in the abundance or distribution of SETs between infants with normal breathing patterns and those with excessively periodic respirations. Nonictal apnea was recorded in 7% of Group 1 infants. The unexpected diagnosis of ictal apnea was confirmed in 2 Group 1 infants (1.2%), and 5 (2.9%) had excessive SETs but no recorded seizures. Only 4 infants (2.3%) had abnormally immature EEGs for conceptional age. Nonictal apnea occurred in 5 of 33 (15.2%) Group 3 infants and ictal apnea was confirmed in 2 others (6.1%). We conclude that the majority of Group 1 and 2 infants have normal cerebral cortical activity between and during apnea and that central nervous system cortical immaturity, as measured by EEG, plays no important role in the pathogenesis of SIDS. SETs are commonly recorded in these infants and must be conservatively interpreted. However, an EEG examination was critical in establishing the unexpected diagnosis of ictal apnea in a small percentage of Group 1 and 3 infants and materially influenced subsequent evaluation, management, and prognosis.

Apnea↗
PubMed1984

Awake apnea associated with gastroesophageal reflux: a specific clinical syndrome.

Fifteen infants with a specific clinical history including awake apnea were evaluated and compared with a control group of infants, using 24-hour studies of esophageal pH, nasal thermistor, impedance pneumography, and heart rate. Thirteen of the 15 children with awake apnea had clearly documented episodes of airway obstruction in associated with gastroesophageal reflux occurring at least twice during the study (mean 3.9 +/- 0.7, range 2 to 9). The control group did not show similar findings. All 15 children with awake apnea had frequent episodes of gastroesophageal reflux. Treatment with home monitoring and reflux precautions was successful in 10 of 15. Five children received therapy with urecholine hydrochloride because of continuing episodes of reflux-associated apnea. Two children subsequently required Nissen fundoplication, primarily for symptoms of severe esophagitis. Our data suggest that in children with awake apnea, the apnea is associated with gastroesophageal reflux. Medical management is usually successful, but fundoplication may be needed in refractory cases.

Apnea↗
PubMed1984

Infant apnea. An approach to management.

Apnea of infancy represents a problem that is commonly encountered by the practicing pediatrician; yet, few publications have outlined a practical approach to the care of such infants. In addition, the somewhat controversial aspects of infant apnea and sudden infant death syndrome (SIDS) have resulted in the belief on the part of many physicians that the care of children with apnea or "near-miss" SIDS is either very difficult or of little value. This article, which is based upon the program at The Children's Hospital of Philadelphia, describes an effective management plan for identifying children at risk, lists appropriate evaluation studies, and presents a series of protocols for treating infants with apnea. The initiation of this program has helped to demystify the care of children with apnea and has been very well received by both parents and physicians.

Apnea↗
PubMed1984

Comparison of airway responses following tracheal or esophageal acidification in the cat.

To determine a possible mechanism for the association between gastroesophageal reflux and obstructive pulmonary disease, we quantitatively compared the short latent airway response after acid infusion into the trachea or esophagus in 13 anesthetized adult cats. Total lung resistance was calculated from synchronous measurements of air flow and intrapleural pressure differences from those at end expiratory level. Tracheal infusion of as little as 0.05 ml of 0.2 N HCl evoked an average 4.65-fold increase in total lung resistance from baseline in all animals tested (p less than 0.005). Intratracheal saline had no effect. The response to intratracheal acid infusion was rapidly adapting, pH dependent, and vagally mediated. Infusion of a much larger volume of 10 ml of 0.2 N HCl into the esophagus produced an average 1.47-fold increase in total lung resistance from baseline (p less than 0.05). No change was seen with intraesophageal saline. In contrast to intratracheal acid infusion, a clearly significant increase in resistance was seen in only 8 of 13 animals tested after intraesophageal acidification. When it occurred, the response was sustained for at least 60 s after acid infusion. The magnitude of the response was not augmented by the presence of severe esophagitis. These studies strengthen the concept that reflex pathways in the trachea and esophagus may explain a causal relationship between gastroesophageal reflux and obstructive pulmonary diseases. The results support the view that microaspiration into the trachea is a much more likely mechanism for bronchospasm associated with gastroesophageal reflux than simple acid reflux into the esophagus.

Airway Resistance↗
PubMed1983

Episodic airway obstruction in premature infants.

Seventy-six premature infants with clinical apnea, bradycardia, or cyanosis were studied with polygraph recordings of heart rate, nasal thermistor detection of airflow, and impedance pneumography. Pathologic apnea was defined by cessation of breathing for greater than 20 s or less than 20 s with bradycardia (heart rate, less than 100 beats per minute). Apnea was classified as central, obstructive, or mixed. Four hundred thirty-three apnea episodes were demonstrated: 238 (55.0%) were central, 53 (12.2%) showed obstructive apnea, and 142 (32.8%) were mixed. Fifty-two infants (68.5%) demonstrated some degree of obstructive apnea, while 24 infants (31.5%) had central apnea only. Bradycardia did not occur in any patient unless preceded by apnea. In premature infants, a significant percentage of apnea was associated with airway obstruction.

Airway Obstruction↗
PubMed1982

Changes in pulmonary function during the diuretic phase of respiratory distress syndrome.

To evaluate the relationship between improvement in pulmonary function and spontaneous diuresis in respiratory distress syndrome, nine premature infants requiring mechanical ventilation for RDS were studied at a mean age of 11.9 hours prior to the onset of diuresis, at onset of diuresis, at maximum urine output (mean age 44.9 hours), and at 24 hours after maximum urine output. Prior to diuresis functional residual capacity decreased from mean +/- SEM of 16.2 +/- 2 to 13.3 +/- 1.2 ml/kg, and dynamic lung compliance decreased from 2.5 +/- 0.3 to 1.8 +/- 0.3 ml/cm H2O (P less than 0.05), indicating that the respiratory disease was worsening. There was no significant change in alveolar-arterial oxygen gradient, peak inflating pressure, or rate of intermittent mandatory ventilation over this period. At the time of maximum urine output, however, FRC had increased 36% (P less than 0.05). CL had increased by 60% to 2.8 +/- 0.4 ml/cm H2O (P less than 0.025), AaDO2 had decreased from 246 +/- 27 to 184 +/- 30 torr (P less than 0.005), and PIP had decreased from 14.9 +/- 2.2 to 11.3 +/- 2.1 cm/H2O (P less than 0.05). On follow-up study 24 hours after maximum urine output, there was no further significant improvement in FRC, CL or PIP, but IMV rate and AaDO2 continued to decrease. These data show that the pulmonary function in RDS deteriorates until the onset of diuresis, after which it rapidly improves. This diuresis may represent the removal of excess lung liquid and seems necessary for improvement in RDS.

Diuresis↗
PubMedDate not supplied

Effect of high-frequency jet ventilation on preterm and rabbit tracheal mechanics.

The effect of high-frequency jet ventilation (HFJV) on both tracheal dimensions and mechanics was evaluated in preterm and term rabbit airways. Seven tracheal segments were studied at 27 days (group I) and 31 days (group II) of gestation, respectively. Tracheal dimensions and segmental pressure-volume relationships were determined before and after 60 minutes of HFJV (peak pressure 20 cm H2O; mean airway pressure 6.7 to 6.8 cm H2O at 10 Hz). Both tracheal lengths and diameters increased significantly (p less than 0.01) in each group and resulted in increased tracheal volumes: 109% in group I (p less than 0.01) and 60% in group II (p less than 0.01). The mean specific tracheal compliance decreased in group I, from 0.036 cm H2O-1 to 0.015 cm H2O-1 (p less than 0.01), and in group II from 0.029 cm H2O-1 to 0.021 cm H2O-1 (p less than 0.01). Furthermore, the collapsing transmural pressure (the pressure required for total collapse of tracheal segments) decreased significantly (p less than 0.01) in both groups. These data demonstrate significant dimensional and mechanical deformation of tracheal segments after HFJV. An increased propensity toward collapsibility is also observed following HFJV. These changes are similar to those with tracheomalacia. The influence of such deformation on tracheal gas flow during HFJV needs to be further investigated.

Animals↗
PubMedDate not supplied

Use of caffeine in infants unresponsive to theophylline in apnea of prematurity.

Eleven premature infants with severe apnea unresponsive to therapeutic theophylline levels were studied to determine if caffeine is an effective treatment in such cases. Apnea was documented and quantitated with thermistor-pneumocardiograms measuring heart rate, thoracic impedance, and nasal air flow. Infants with prolonged central or mixed apnea were then treated with caffeine and restudied. Caffeine reduced the total number of apneic episodes of greater than 10 sec duration by 80% (P less than 0.01) and prolonged episodes of apnea (greater than 20 sec) by 88% (P less than 0.05). These data suggest that caffeine may be effective in the management of apnea of prematurity, particularly the prolonged type, unresponsive to theophylline.

Apnea↗
PubMedDate not supplied

Effect of early furosemide administration in neonates with respiratory distress syndrome.

The effect of early furosemide-induced diuresis was prospectively evaluated in 39 neonates less than 24 hr of age with clinical respiratory distress syndrome (RDS) who received either four doses of furosemide (1 mg/kg) or no diuretic. Measurements of FiO2 alveolar-arterial oxygen gradient (P[A-a]O2), peak inspiratory pressure (PIP), and urine output as a fraction of intake (O/I) were averaged for every 8 hr. The furosemide group overall showed a significant decrease (P less than 0.01) in FiO2, P[A-a]O2, and PIP with an earlier (32 hr vs 52 hr) and more pronounced diuresis (35% greater O/I) when compared to the controls. This effect was accentuated in the subgroup with 1,000-1,500 g birth weight (significantly lower FiO2 and P(A-a)O2 from 16 to 48 hours), while no increase in urine output was observed for the infants weighing less than 1,000 g. A significant reduction in supplemental oxygen and need for ventilatory support at 96 hr of age was observed in the furosemide-treated, less than 1,500-g infants. The incidence of patent ductus arteriosus was not increased following furosemide therapy, and no significant difference in echocardiographic parameters was observed in 21 infants from both groups, who were followed daily during the first week of life. This study suggests that early furosemide-induced diuresis, particularly in infants weighing 1,000-1,500 g at birth, promotes improvement in pulmonary functions in RDS and leads to faster reduction in oxygen and ventilatory support.

Birth Weight↗
PubMedDate not supplied

Utility of serial EEGs in neonates during extracorporeal membrane oxygenation.

We found electroencephalographic (EEG) studies to be useful for monitoring cerebral function, for confirming seizure activity, and for limited prediction of short-term outcome in 145 neonates who required extra-corporeal membrane oxygenation (ECMO) of reversible respiratory failure. The EEG tracings were classified as normal or as mildly, moderately, or markedly abnormal; abnormal recordings were further classified as focal, diffuse, or predominantly lateralized. A significant decrease in frequency and degree of EEG abnormalities was observed in recordings obtained after ECMO compared to those obtained prior to (P = .001) or during ECMO (P = .001). There was no significant increase in marked EEG abnormalities when recordings obtained before and during ECMO were compared (P = 0.41). Of 11 infants with electrographic seizures during ECMO, 7 (64%) either died during their nursery courses or were developmentally handicapped at age 1 year which is a significantly greater adverse outcome than that observed in infants without EEG seizure activity (P less than .003). No consistently lateralized EEG abnormalities were observed during or after ECMO when compared to tracings obtained before cannulation of the right common carotid artery. There was no acute change in EEG rhythm or amplitude over the right cerebral hemisphere during right common carotid artery cannulation. Our observations support the value of serial EEG in the assessment of cerebral function in critically ill infants undergoing ECMO. They further suggest that, in this patient population, cannulation of the right common carotid artery is a safe procedure that does not result in lateralized abnormalities of cerebral electrical activity.

Brain Damage, Chronic↗
PubMedDate not supplied

When combined, early bedside head ultrasound and electroencephalography predict abnormal computerized tomography or magnetic resonance brain images obtained after extracorporeal membrane oxygenation treatment.

Definitive neuroimaging of the brain using computerized tomography (CT) or magnetic resonance imaging (MRI) in extracorporeal membrane oxygenation (ECMO)-treated infants must be delayed until after this therapy is completed. Bedside head ultrasound (HUS) and electroencephalography (EEG) studies during ECMO, if highly correlated with later definitive neuroimaging, might be used to affect the acute clinical care and early parental counseling of infants with severe cardiorespiratory failure. One hundred and sixty ECMO-treated patients had both bedside EEG and HUS studies performed during ECMO, as well as a later CT or MRI study prior to hospital discharge. There was a significant difference in CT or MRI findings among patients having normal studies on both the HUS and EEG, compared to those having an abnormality on either the HUS or the EEG, and compared to those having abnormalities on both studies. In ECMO-treated infants, the combination of a normal bedside HUS and an EEG without marked abnormalities is highly predictive of normal post-ECMO CT and MRI neuroimaging studies.

Brain↗
PubMedDate not supplied

Congenital diaphragmatic hernia: prognosis and prenatal detection.

Fifty consecutive cases of isolated congenital diaphragmatic hernia were reviewed for prenatal ultrasound and neonatal physical findings. These were compared to survival and the need for extracorporeal membrane oxygenation (ECMO). No prenatal findings predicted survival or the need for ECMO. In left-sided hernias, the presence of the liver in the chest predicted (p = 0.02) the requirement for ECMO. In a cohort of 13 prenatally diagnosed inborn cases, the ultrasound triad of polyhydramnios, mediastinal shift and intrathoracic stomach predicted the presence of liver in the chest (p < 0.03).

Extracorporeal Membrane Oxygenation↗