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Biomedical subjects

J A Kitterman

Publications and source records attributed to J A Kitterman.

17 recordsLinked to original sources
PubMed1992

Effects of acute oligohydramnios on respiratory system of fetal sheep.

Prolonged oligohydramnios, or a lack of amniotic fluid, is associated with pulmonary hypoplasia and subsequent perinatal morbidity, but it is unclear whether short-term or acute oligohydramnios has any effect on the fetal respiratory system. To investigate the acute effects of removal of amniotic fluid, we studied nine chronically catheterized fetal sheep at 122-127 days gestation. During a control period, we measured the volume of fluid in the fetal potential airways and air spaces (VL), production rate of that fluid, incidence and amplitude of fetal breathing movements, tracheal pressures, and fetal plasma concentrations of cortisol, epinephrine, and norepinephrine. We then drained the amniotic fluid for a short period of time [24-48 h, 30.0 +/- 4.0 (SE) h] and repeated the above measurements. The volume of fluid drained for the initial studies was 1,004 +/- 236 ml. Acute oligohydramnios decreased VL from 35.4 +/- 2.9 ml/kg during control to 22.0 +/- 1.6 after oligohydramnios (P less than 0.004). Acute oligohydramnios did not affect the fetal lung fluid production rate, fetal breathing movements, or any of the other measured variables. Seven repeat studies were performed in six of the fetuses after reaccumulation of the amniotic fluid at 130-138 days, and in four of these studies the lung volume also decreased, although the overall mean for the repeat studies was not significantly different (27.0 +/- 5.2 ml/kg for control vs. 25.5 +/- 5.5 ml/kg for oligohydramnios). Again, none of the other measured variables were altered by oligohydramnios in the repeat studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1979

Postnatal lung growth after repair of diaphragmatic hernia.

The lungs of two patients who died eight months and 64 months after repair of a left-sided diaphragmatic hernia on the first day of life were examined. Lung volumes were appropriate for the size of the children, and the ratio of right lung volume to left lung volume was also normal in both patients. The lungs, however, were grossly abnormal with evidence of enlargement and destruction of respiratory tissue. The left lung was affected more than the right in both subjects. In one patient the total number of alveoli in the lungs was similar to that of normal children of the same age, but this was because the right lung had more than twice as many alveoli as the left lung. It appears that alveolar multiplication is impaired after repair of diaphragmatic hernia. The number of bronchioles was reduced in the infant with very few alveoli, and there may have been too few bronchioles in the other patient.

Child, Preschool↗
PubMed1979

Tracheal fluid in fetal lambs: spontaneous decrease prior to birth.

We studied tracheal fluid (TF) production in 14 fetal lambs: 6 controls, 6 receiving atropine on 1 or more of the last 7 days before birth, and 2 with bilateral section of the cervical vagosympathetic trunk. A cannula diverted all TF into an intrauterine bag; we collected TF intermittently and measured its volume. All ewes delivered spontaneously at 128-150 days' gestation. TF production decreased before birth in all fetuses except one control. TF production decreased before birth in all fetuses except one control. TF production did not correlate with fetal arterial blood gas tensions, hematocrit, or plasma proteins. In controls only, TF production correlated with fetal arterial pH (P less than 0.02); however, the pH range was small and the correlation has questionable physiological significance. For all fetuses, TF production during the 7 days before birth correlated inversely with the plasma cortisol concentration of 48 h previously (n = 36; r = -0.603; P less than 0.001). We conclude a) TF production in fetal lambs decreases before spontaneous term or preterm labor; b) this decrease is not affected by atropine or by section of the cervical vagosympathetic trunk; and c) the decrease in TF production may be related to increased secretion of cortisol.

Animals↗
PubMed1979

Stimulation of breathing movements in fetal sheep by inhibitors of prostaglandin synthesis.

We studied the effects of inhibitors of prostaglandin synthesis on fetal breathing movements on 17 occasions in 11 lambs (gestational age 125-141 days). We gave 12 h infusions of sodium mechlofenamate (8.6-22.2 mg.kg-1) in 13 studies and indomethacin (21.8-38.8 mg.kg-1) in four studies. Results were similar with both agents and did not correlate with drug dosage. There were no changes in fetal arterial blood pressure, pH or blood gas tensions. We assessed fetal breathing movements by measurements of tracheal pressure for a control period of 224 h prior to and 208 h during the infusion of inhibitors of prostaglandin synthesis; their administration caused a marked stimulation of fetal breathing movements judged from the following four variables: (1) incidence of fetal breathing movements increased from 38.4 to 69.2% of the time (P < 0.001); (2) average amplitude of change in tracheal pressure during fetal breathing movements increased from 4.1 to 6.0 torr (P < 0.01); (3) maximal amplitude of change in tracheal pressure during fetal breathing movements increased from 8.8 to 13.4 torr (P < 0.01); and (4) the duration of the longest continuous episode of fetal breathing movements increased from 37 to 229 min (P < 0.05). Two fetuses had electrocorticogram (ECoG) recordings. In control periods, fetal breathing movements occurred only during low voltage, high frequency ECoG activity; however, during infusions of inhibitors of prostaglandin synthesis, fetal breathing movements occurred also during high voltage, low frequency ECoG activity. We conclude that inhibitors of prostaglandin synthesis stimulate fetal breathing movement in fetal sheep. These results suggest that a component of the prostaglandin system is a factor which inhibits breathing movements during fetal life.

Animals↗
PubMed1978

Failure to detect an effect of prolactin on pulmonary surfactant and adrenal steroids in fetal sheep and rabbits.

Recent reports have indicated an association between low cord prolactin (PRL) and the occurrence of respiratory distress syndrome in premature infants, and it is reported that PRL administration increases the lecithin content of fetal rabbit lung. We administered 1 mg ovine PRL to 32 rabbit fetuses on day 24 of gestation and evaluated lung phospholipid synthesis and content on day 26. Compared with diluent-injected littermates, PRL had no effect on the rate of choline incorporation into lecithin, tissue content of phospholipid and disaturated lecithin, or plasma corticoids. However, both choline incorporation and corticoids were increased in all animals undergoing surgery compared with unoperated controls. We also infused PRL (1 mg/day, i.v.) into three fetal sheep continuously over five periods of 5-8 days. Although supraphysiologic concentrations of PRL were achieved in plasma and amniotic fluid, there was no effect of this treatment on the flux of tracheal fluid surfactant or on plasma concentrations of corticoids of dehydroepiandrosterone sulfate. Thus, in this study, we failed to detect either a stimulation of the surfactant system or an adreno-corticotropic effect by PRL as previously postulated. This suggests that the relationship between PRL and respiratory distress sundrome is an indirect association.

Adrenal Cortex Hormones↗
PubMed1977

The effect of time of cord clamping and maternal blood pressure on placental transfusion with cesarean section.

We measured the residual placental blood volume (RPBV) of 20 infants delivered at term by cesarean section of women not in labor. In all cases, the umbilical cord was clamped within 40 seconds of birth. RPBV decreased significantly with increasing age at cord clamping. In addition, RPBV for infants with cords clamped within 20 seconds of birth correlated inversely with maternal systolic blood pressure (mean RPBV = 54.8 ml. per kilogram at 105 torr and 28.4 ml. per kilogram at 148 torr). However, RPBV did not correlate with maternal blood pressure for the whole group of 20 infants or for those with cords clamped later than 20 seconds after birth. These data indicated that in infants delivered by cesarean section placental transfusion is time related during the first 40 seconds of life and that maternal blood pressure also influences the magnitude of placental transfusion during the first 20 seconds after birth. Analysis of data from this study combined with data from a previous study shows that after 40 seconds the net flow between placenta and infant reverses and that cord clamping delayed beyond this point is accompanied by a rise in RPBV back to the level found when the cord was clamped before 20 seconds.

Blood Pressure↗
PubMed1977

Radioimmunoassay of pulmonary surface-active material in the tracheal fluid of the fetal lamb.

We measured pulmonary surfactant antigen by radioimmunoassay and phospholipid by lipid phosphorus assay in fluid collected during 12-hour periods from the trachea of lambs in utero between 102 and 147 days of gestation. Both phospholipid and antigen were detectable at 114 days and were present at low concentrations until 137 days. The concentrations then increased rapidly and reached 5- to 10-fold higher concentrations before parturition. The ratio of lipid phosphorus to antigen increased approximately 5-fold as the lungs passed from canalicular to alveolar architecture and approximated the adult ratio only during the alveolar stage of development.

Animals↗
PubMed1976

Persistent pulmonary hypertension of the newborn infant.

Persistent pulmonary hypertension of the newborn infant can be difficult to distinguish from other cardiopulmonary causes of cyanosis during the newborn period. Infants with PPHN have cyanosis, tachypnea, acidemia, normal pulmonary parenchymal markings on the chest radiography, and anatomically normal hearts. We have identified and treated 11 infants and have noted several signs and symptoms not previously emphasized. These are cineangiocardiographic evidence of atrioventricular valve insufficiency in association with systolic murmurs and slow ventricular emptying, apnea, hypocalcemia, only a small rise in abdominal aortic blood oxygen tension during breathing of 100% oxygen, and no response to continuous positive airway pressure. Right-to-left shunting through the patent ductus arteriosus was documented in nine infants: in all six of those in whom simultaneous temporal and abdominal aortic blood oxygen tension measurements were made; in three by means of cardiac catheterization. Ten infants survived after variable courses and treatments which makes it difficult to ascribe improvement to any one therapy. The distinct increase in blood oxygen tension with tolazoline HCl and curare in some instances is discussed.

Cyanosis↗
PubMed1976

Pneumothorax in the respiratory distress syndrome: incidence and effect on vital signs, blood gases, and pH.

We determined the incidence of pneumothorax in 295 infants (mean birthweight, 1,917 gm) with the respiratory distress syndrome (RDS) treated according to the same protocol. Fifty-five infants (mean birthweight, 1,594 gm) developed pneumothorax (incidence, 19%); incidence varied with severity of RDS and intensity of respiratory assistance. Pneumothorax occurred in 3.5% (2 of 58) of infants who received no assisted ventilation and in 11% (14 of 124) of infants who received continuous positive airway pressure (CPAP) as the only form of assisted ventilation; the difference between these two groups is not significant. Forty-nine infants initially treated with CPAP later required mechanical ventilation with positive end-expiratory pressure (PEEP). Pneumothorax occurred in 12 of the 49 (24%) and in 21 of 64 (33%) of those infants initially treated with PEEP; the incidence of pneumothorax for both these groups was significantly higher than for those treated with no assisted ventilation or CPAP only. To assess the value of frequent measurement of vital signs, blood gas tensions, and pH in the recognition of pneumothorax, we analyzed these variables by the cumulative sum statistical technique. We noted the following significant changes associated with pneumothorax: arterial blood pressure, heart rate, and respiratory rate decreased in 77% of cases; pulse pressure narrowed in 51% of cases; Po2 decreased in 17 of 20 cases in which ventilatory settings were constant for at least three hours prior to pneumothorax. However, pH and Pco2 showed consistent changes. Frequent measurements of vital signs and Po2 aid in the early diagnosis of pneumothorax.

Blood Pressure↗
PubMed1976

Cardiorespiratory status of erythroblastotic newborn infants: III. Intravascular pressures during the first hours of life.

We measured aortic and central venous pressures beginning soon after birth in 40 prematurely born infants with moderate or severe erythroblastosis fetalis, including 13 with severe and 10 with mild hydrops fetalis. All but four were asphyxiated at birth and this affected intravascular pressures. Before resuscitation, aortic or central venous pressure or both were elevated in more than one third. All but two of the remaining infants had normal initial pressures. Following resuscitation which relieved acidosis, hypoxia, and anemia, but did not reduce blood acidosis, hypoxia, and anemia, but did not reduce blood volume, the high pressures usually fell to normal and occasionally to subnormal levels, normal pressures fell to subnormal in almost one half, and those with initial subnormal pressures remained hypotensive. In all, 40% were hypotensive after resuscitation; treatment with blood volume expanders consistently returned these pressures to normal. Only two of the 13 severely hydropic infants and none of the mildly hydropic had findings indicative of hypervolemia and myocardial failure which persisted after treatment of asphyxia.

Animals↗
PubMed1975

Continuous positive airway pressure and pulmonary and circulatory function after cardiac surgery in infants less than three months of age.

Continuous positive airway pressure (CPAP) was used to support the ventilation of infants less than 3 months of age who had undergone thoractomy for cardiovascular surgery. The functional residual capacity, which was approximately 30 per cent of predicted at zero CPAP, increased 35 per cent in cyanotic and 33 per cent in acyanotic infants with the application of 5 mm Hg pressure. Increasing airway pressure from zero to 5 mm Hg increased PaO2 4 per cent in cyanotic and 13 per cent in acyanotic infants. There was no change in heart rate, respiratory rate, mean arterial pressure, pH or PaC02 under similar circumstances, but central venous pressure increased 1.5 mm Hg in cyanotic and 0.8 mm Hg in acyanotic infants.

Blood Circulation↗
PubMed1975

Ontogeny of tracheal fluid, pulmonary surfactant, and plasma corticoids in the fetal lamb.

We examined fetal plasma corticoids and flow rate, electrolyte composition, and surfactant content of tracheal fluid in chronic experiments with eight fetal lambs. From 120 to 148 days of gestation the rate of fluid production was 4.5 ml/kg per h, and there was no change in mean fluid sodium (147.8 meq/1), chloride (153.1 meq/1), calcium (2.2 mg/100 ml), and pH (6.23). Tracheal fluid potassium increased from 4.3 meq/1 at 120-130 days to 8.9 meq/1 at term, while plasma sodium, chloride, calcium, pH, and potassium were constant at 146.1 meq/1, 110.0 meq/1, 12.1 mg/100 ml, 7.39, and 4.0 meq/1, respectively. Plasma corticoids were less than 1.5 mug/100 ml total (0.3 mug/100 ml free) until 130 days, when they increased rapidly to 10.5 total (3.2 free) at 148 days. Surfactant was first detected in tracheal fluid between 124 and 133 days and its secretion increased rapidly after 135 days to a value of 125 mug/kg per h at 148 days. A sudden increase in fetal plasma corticoids does not seem to be the stimulus for appearance of surfactant in the lamb, although these hormones may induce the rapid accumulation of surfactant prior to delivery.

Adrenal Cortex↗
PubMed1975

Congenital heart disease in low birth weight infants.

In this study of low birth weight infants (less than 2500 g), we compared the birth weight distribution of patients with patent ductus arteriosus associated with prematurity with that of patients having congenital heart disease other than patent ductus arteriosus. Among 1436 low birth weight infants 37 infants had congenital heart disease other than patent ductus arteriosus and 198 had isolated ductus arteriosus. Infants with congenital heart disease had a mean birth weight of 2018 grams (standard deviation = 370 g) which was significantly greater than that of infants with patent ductus arteriosus. Four of the 37 infants with congenital heart disease other than ductus arteriosus were among 1150 low birth weight infants born in this institution, an incidence of 3.5/1000 live low birth weight infants. Seventy-eight of the 198 infants with patent ductus arteriosus were among 1150 low birth weight infants born in this institution, an incidence of 70/1000 live low birth weight infants. Twenty-one of the 37 infants with congenital heart disease were of appropriate weight for gestational age and 16 were small for gestational age.

Aorta↗
PubMed1975

Surfactant in the lung and tracheal fluid of the fetal lamb and acceleration of its appearance by dexamethasone.

We measured tracheal fluid production rate and pulmonary surfactant flux in 12 sets of twin fetal lambs of 102 to 135 days' gestation. In nine of these sets we also measured surfactant flux and the concentration of saturated lecithin in the lungs before and during dexamethasone infusion into one of the twins. The average tracheal fluid flow rate was 3.25 ml/kg/hr (SD 1.6) and, relative to body weight, did not change between 103 and 135 days' gestation or during the infusion of dexamethasone. In untreated fetuses, surfactant was detected between 108 and 130 days and its flux gradually increased but remained less than 150mug/kg/hr at 135 days' gestation; the amount of disaturated lecithin in the lung relative to body weight increased 13-fold from 108 to 134 days. From these data we calculated that the minimal rate of synthesis of disaturated lecithin was increased about 4-fold by dexamethasone from 108 to 120 days; this enhancement fell to about 1.8-fold by 135 days. The rate of secretion of disaturated lecithin, as estimated by surfactant flux in tracheal fluid, was increased by dexamethasone throughout the interval of the study.

Animals↗