Luis A Cabal

Cardiogenic shock associated with perinatal asphyxia in preterm infants

Fetal and neonatal biophysical and biochemical changes were studied in four preterm infants who developed cardiogenic shock as a result of severe perinatal asphyxia. Fetal distress was documented by the presence of severe late and variable decelerations associated with decreased fetal heart rate variability. Severity of fetal acidosis was decumented by scalp and umbilical cord blood pH. Apgar scores at 1, 5, and 10 minutes were all equal to or less than 5. Although the clinical findings shortly after birth resembled respiratory distress syndrome, it was possible to make a primary diagnosis of cardiac failure with the recognition of cardiomegaly, hepatomegaly, electrocardiographic changes of myocardial hypoxia, decreased myocardial contractility, elevated central venous pressure, and severe lactic acidosis. The treatment of heart failure, including use of inotropic agents, resulted in rapid improvement in the clinical condition, with reversal of the abnormal findings within 24 to 36 hours. Concomitant with this improvement, the increase in arterial blood pressure was paralleled by increase in peripheral (toe) temperature.

Cardiopulmonary and intracranial pressure changes related to endotracheal suctioning in preterm infants

Although endotracheal (ET) suctioning is performed frequently in sick newborn infants, its effects on cardiorespiratory variables and intracranial pressure (ICP) have not been thoroughly documented in neonates greater than 24 h who were not paralyzed while receiving mechanical ventilation. This study evaluates these changes in preterm infants who required ventilatory assistance. We measured transcutaneous PO2 and PCO2 (PtcO2 and PtcCO2, respectively), intra-arterial BP, heart rate, ICP, and cerebral perfusion pressure (CPP) before, during, and for at least 5 min after ET suctioning in 15 low birth weight infants less than 1500 g and less than or equal to 30 days of age. One infant was studied twice. A suction adaptor was used to avoid disconnecting the patient from the ventilator and to attempt to minimize hypoxemia and hypercapnia during suctioning. The patients were studied in the supine position and muscle relaxants were not used. PtcO2 decreased 12.1% while PtcCO2 increased 4.7% 1 min after suctioning; however, greater increases in mean BP (33%) and ICP (117%) were observed during suctioning. CPP also increased during the procedure. ICP returned to baseline almost immediately, whereas BP remained slightly elevated 1 min after suctioning. Our findings demonstrate that ET suctioning significantly increases BP, ICP, and CPP in preterm infants on assisted ventilation in the first month of life. These changes appear to be independent of changes observed in oxygenation and ventilation.

Effects of metaproterenol on pulmonary mechanics, oxygenation, and ventilation in infants with chronic lung disease

Changes in pulmonary resistance, dynamic compliance, tidal volume, and transcutaneous PO2 and PCO2 after nebulized administration of metaproterenol were evaluated in eight newborn infants (birth weight 650 to 1060 g, gestational age 25 to 28 weeks) with chronic lung disease receiving mechanical ventilation. The infants were monitored continuously before and for 15 minutes after nebulization of metaproterenol during 3 consecutive days at mean age 34 days. There were significant increases in compliance, tidal volume, and tcPO2, and significant decreases in pulmonary resistance and tcPCO2. These data show that bronchospasm contributes significantly to the high pulmonary resistance in preterm infants with chronic lung disease and that metaproterenol is beneficial in the therapy of infants with chronic lung disease requiring mechanical ventilation.

New endotracheal tube adaptor reducing cardiopulmonary effects of suctioning.

The continuous recordings of arterial oxygen saturation (SaO2) and beat-to-beat heart rate before, during, and after tracheobronchial suctioning were studied in eight preterm infants with severe RDS receiving mechanical ventilation. Two suctioning procedures were alternatively performed in each infant; In procedure A, disconnection of the ventilator and preoxygenation preceded suctioning; in procedure B, a special suction adaptor was used without ventilatory interruption or preoxygenation; 128 suctionings were performed with each procedure and the changes in heart rate (HR) and SaO2 during suctioning were compared. Although in both procedures, HR and SaO2 decreased during suctioning, the degree of bradycardia and arterial blood oxygen desaturation were significantly smaller in magnitude and shorter in duration during procedure B. These data indicate advantages of the suction adaptor in minimizing bradycardia and hypoxia from airway suction.

Cardiac and respiratory activity in relation to gestation and sleep states in newborn infants.

Summary: In order to provide normative values of heart and respiratory rate and variability in relation to gestation and sleep states, 32 neonates who were free from cardiopulmonary disease were studied during the 1st-6 day of life. The infants were grouped as follows: group A, 9 infants with gestational ages of 27-33 wk; group B, 14 infants with gestational ages of 34-36 wk; and group C, 9 infants with gestational ages of 37-40 wk. Recordings and observations were made during a 1-hr postprandial nap. During active sleep (AS) and quiet sleep (QS), heart rate, short-term and long-term variability of the heart rate, respiratory rate, variability of the respiratory rate and apnea density were measured. Both the long- and short-term heart rate variability was less in preterm infants (group A) than the less immature or full term infants (groups B and C, P <0.01). Breath-to-breath respiratory variability was not significantly affected by gestational age, whereas percent duration of apnea was less in full term (group C) than the preterm groups of infants during quiet sleep (groups A and B, P < 0.05). There was no significant difference between baseline heart rate, short-term heart rate variability, and respiratory rate during AS and QS states at any given gestational age. Long-term variations in heart rate, breath-to-breath respiratory variability, and percent duration of apnea were significantly less in QS in comparison to AS at each gestational age group (P < 0.01).Speculation: Systematic monitoring of newborn infants by the techniques presented in this report would further define normal cardiorespiratory functions in relation to maturity and sleep states. Application of these techniques to the study of the distressed newborn should provide an early indication of morbidity and recovery from disease.

Transcutaneous Oxygen and Carbon Dioxide during the First Half Year of Life in Premature and Normal Term Infants

ABSTRACT: Repetitive polysomnograms were recorded from a total of 33 infants, 19 healthy preterm infants, and 14 term controls between 40 wk postconceptional age and 6 mo of age. These nighttime recordings lasted 2—4 h, except at 52 wk in preterm infants and at 3 mo of age in term infants when an overnight 12-h recording was performed. Minute by minute values of transcutaneous Po. (Ptco2) and transcutaneous PCO2 (PtcCO2) levels and variability during the awake state, active sleep, and quiet sleep were obtained through computer analyses of the polygraphic data. The results from preterm infants at corrected postconceptional age could not be differentiated from those of control infants. PtcO2 levels rose between 40 wk and 3 mo, and PtcCO2 levels declined. Sleep states modulated only the variability of PtcO2, not the level; in contrast, state modulation was seen in both variability and level of PtcCO2 throughout the age span studied. During sleep the number of transient declines in PtcO2 > 2.03 kPa (15 mm Hg) decreased with advancing age. Hypercapnic PtcCO2 values decreased with age as well, but their prevalence in healthy, young infants suggests the need for revaluation of criteria for hypercapnia based on transcutaneous measurements. The data demonstrate that ventilatory regulation continues to undergo changes between 1 and 3 mo, the age of highest risk for sudden infant death syndrome.

Surgical closure of patent ductus arteriosus in the premature infant with respiratory distress

During the period from February, 1971 to February, 1973, 30 premature infants underwent surgical ligation of patent ductus arteriosus. The gestational ages ranged from 25 to 36 wk (mean 30), and the birth weights ranged from 760 to 2010 g (mean 1274). The patients were divided into two groups on the basis of the indications for assisted ventilation. Group I consisted of 21 patients with severe hylanine membrane disease who required assisted ventilation during the first 2 days of life and could not be weaned off the respiratory by 10 days of age. Group II was composed of nine infants who required intermittent positive-pressure breathing after a mean age of 8 days because of repeated apneic spells secondary to uncontrollable heart failure. All infants in Group II survived the operation and left the hospital well. Fourteen of the 21 patients in Group I survived; the seven deaths were all due to underlying severe pulmonary disease (bronchopulmonary dysplasia). The value of PDA ligation in premature infants with uncontrollable heart failure is demonstrated in this study; this procedure also appears to be beneficial in neonates with severe respiratory distress syndrome.

Heart rate and blood pressure in infants of pre-eclamptic mothers during the first hour of life.

Neonatal heart rate (HR) and arterial blood pressure (BP) were recorded continuously for the 1st hour of life in term newborn infants of normotensive (control group) and pre-eclamptic (study group) primiparous mothers. Infants were matched for gestational age, birth weight, method of delivery, and Apgar scores. In infants of pre-eclamptic mothers, the HR was significantly lower for the 1st 50 min of life, and their mean arterial blood pressure (MAP) was significantly higher during the 1st 20 min of life.

Factors affecting heated transcutaneous Po2 and unheated transcutaneous Po2 in preterm infants

The authors evaluated transcutaneous Pco2 (PtcCo2) and Po2 (PtcO2) electrodes in 25 infants. Their diagnosis were severe hyaline membrane disease (HMD) (18), aspiration syndrome (3), severe hydrops, (3) persistent fetal circulation (6), and the others, congenital pneumonia, congenital plural effusion, pulmonary hemorrhage. In almost all, the cardiovascular system was compromised, i.e., PDA with congestive heart failure and shock. PtcO2 electrode was heated to 43.5°C while PtcCO2 electrode was not heated. Simultaneous arterial blood pressure (ABP), pH, arterial blood gases were obtained with the transcutaneous gas measurements. The data were analyzed first dividing all the paired arterial and transcutaneous gas tensions into those with and without cardiovascular drugs (dopamine, isoproterenol), and second, the paired values were divided into those taken (a) during severe acidosis (pH < 7.25), (b) hypotension (<2 SD) of normal, and (c) hypotension and acidosis. These data show: (1) the unheated PtcCO2 and heated PtcO2 accurately correlated with the simultaneous arterial measurements; (2) Ptcco2 reflects tissue Pco2; (3) drugs affect both Ptco2 and Ptco2; (4) elevated Ptcco2 dissociating from the simultaneous Paco2 in neonates with cardiovascular compromise results from decreased tissue perfusion. These data suggest that transcutaneous gas sensors perform dual functions; first, as gas monitors in patients without cardiovascular alterations, and second, in patients with cardiovascular compromise, Ptcco2 reflected tissue perfusion and Ptco2 monitored oxygen delivery to the tissues.

120 ELEVATED BLOOD PRESSURE IN INFANTS OF PRE-ECLAMPTIC MOTHERS

Although Woodbury et al, (Am.J. Physiol.122;472, 1938) implicated maternal toxemia as a cause of high blood pressure in neonates, there have been no further studies confirming this association. We retrospectively analyzed data from 500 high-risk pregnancies studied in 1972*. Eighteen term infants born to preeclamptic mothers (group 1) were matched for birth weight, GA, Apgar scores and hematocrit with infants born to non-preeclamptic and otherwise asymptomatic mothers (group 2). We retrived the heart rate (HR) intra-arterial blood pressure (ABP), and arterial blood gases. The data were obtained from one min. windows at a mean age of 4 mins. and at 10 min. intervals for the first 60 min. Heart rate levels were lower in group 1 than group 2 (p<.01) throughout the first 50 min. of life. Initial values for mean ABP were 49±5.0 in group 1 and 43±5.1 in group 2. Mean ABP remained higher in group 1 up to 30 min. (p<.001). No significant differences were found in PaO2 or PaCO2. These results show that term infants of preeclamptic mothers have significantly elevated ABP associated with lower HR during the immediate postnatal period, confirming the observations of Woodbury et al: The association of high blood pressure and pre-eclampsia has also been reported in older children. Transient elevation of blood pressure in the infant born to mothers with pre-eclampsia may be a precursor of later hypertension in childhood.