June P. Brady

Abnormal cerebral blood flow patterns in preterm infants with a large patent ductus arteriosus

To determine whether there are significant alterations in cerebral blood flow patterns in infants with a patent ductus arteriosus and whether these alterations correlate with alterations in aortic blood flow, we performed range-gated pulsed-Doppler examinations of the aorta and cerebral arteries in 20 infants. Ten infants had a PDA and ten control infants did not. We analyzed these flow patterns quantitatively by calculating the pulsatility index (peak systolic frequency minus trough diastolic frequency)/peak systolic frequency. In the ten control infants and in three infants with a small PDA, there was no significant diastolic flow in the descending aorta; flow in the cerebral arteries was antegrade throughout systole and diastole (PI = 0.75 +/- 0.03 for control infants and 0.73 +/- 0.07 for small PDA infants). In seven infants with a large PDA, there was retrograde diastolic flow in the descending aorta. This pattern was not seen after PDA closure. In the cerebral arteries of the seven infants with a large PDA, diastolic flow was retrograde in three and decreased or absent in four, and PI was significantly higher (PI = 0.96 +/- 0.06. P less than 0.001 vs controls). After PDA closure, cerebral diastolic flow was antegrade in all seven infants (PI = 0.74 +/- 0.04). We conclude that a large PDA can cause abnormal flow patterns in the descending aorta and cerebral arteries. These flow patterns may predispose these infants to CNS ischemia or intraventricular hemorrhage.

Tracheal suction in meconium aspiration

We performed a retrospective study of the morbidity and mortality rates of 125 infants, born through meconium-stained amniotic fluid, and admitted to the newborn intensive-care unit for observation. A comparison was made of maternal age, history of toxemia, type of anesthesia, duration of analgesia, presence of cord complications, abnormalities of fetal heart rate, duration of meconium staining, birth weight, gestational age, 1 and 5 minute Apgar scores, and type of resuscitation between infants who were symptomatic or asymptomatic in the unit. Forty-three developed respiratory distress (symptomatic) and eight died; 82 were asymptomatic. The only difference between the two groups was a history of immediate tracheal suction in the delivery room. Of 97 infants receiving immediate tracheal suction, 27 became symptomatic and one died--an infant with Downs syndrome and endocardial cushion defect. On the other hand, of 28 infants who did not receive immediate tracheal suction, 16 became symptomatic and seven died of massive meconium aspiration pneumonitis (P less than 0.001). We concluded that in infants born through meconium-stained amniotic fluid, immediate tracheal suction is a safe procedure that significantly lowers the morbidity and mortality rates and produces no further respiratory depression of the infant.

Chemoreceptor reflexes in the new-born infant: effects of varying degrees of hypoxia on heart rate and ventilation in a warm environment

1. We studied the effects of varying degrees of hypoxia for 3 min periods on the heart rate and respiration of thirty‐three healthy full‐term infants in a warm environment.

Controlled trial of furosemide therapy in infants with chronic lung disease

To study the effects of furosemide therapy in infants with chronic lung disease (CLD), a double-blind controlled trial was designed. Seventeen infants with evidence of CLD (oxygen requirements greater than 30% at greater than 3 weeks of age and chest radiographic findings consistent with CLD) were studied. Pulmonary function was measured immediately before, and after 48 hours and 7 days of treatment with furosemide (1 mg/kg/12 hr intravenously or 2 mg/kg/12 hr orally) or placebo. Clinical status improved in six of seven infants who received furosemide and in two of 10 infants who received placebo (P less than 0.002). In the furosemide group, ventilator and oxygen requirements decreased (P less than 0.003); minute ventilation, alveolar ventilation, and dynamic compliance increased; and venous admixture decreased (P less than 0.05). There were no significant changes in the placebo group. Our findings suggest that furosemide significantly improves lung function during therapy in infants with CLD and allows earlier weaning from ventilatory support and supplemental oxygen.

Marketing breast milk substitutes: problems and perils throughout the world

On 21 May 1981 the WHO International Code of Marketing Breast Milk Substitutes (hereafter referred to as the Code) was passed by 118 votes to 1, the US casting the sole negative vote. The Code arose out of concern that the dramatic increase in mortality, malnutrition and diarrhoea in very young infants in the developing world was associated with aggressive marketing of formula. The Code prohibited any advertising of baby formula, bottles or teats and gifts to mothers or ‘bribery’ of health workers. Despite successes, it has been weakened over the years by the seemingly inexhaustible resources of the global pharmaceutical industry. This article reviews the long and tortuous history of the Code through the Convention on the Rights of the Child, the HIV pandemic and the rare instances when substitute feeding is clearly essential. Currently, suboptimal breastfeeding is associated with over a million deaths each year and 10% of the global disease burden in children. All health workers need to recognise inappropriate advertising of formula, to report violations of the Code and to support efforts to promote breastfeeding: the most effective way of preventing child mortality throughout the world.

Control of ventilation in subsequent siblings of victims of sudden infant death syndrome

To learn whether the ventilatory responses to hypoxia (17% O2) and hypercapnea (4% CO2) differ in the subsequent siblings of sudden infant death victims (SIDS), we studied seven normal control infants, nine infants who had had a prolonged apneic spell (apneic infants), and 10 subsequent siblings of SIDS (mean ages 10.4 weeks, 15 weeks, and 10 weeks, respectively). With inhalation of 17% O2, one of seven controls, two of nine apneic infants, and seven of 10 siblings of SIDS breathed periodically (controls vs siblings, P less than 0.04). Heart rate and end-tidal PCO2 did not change, but respiratory rate decreased in the siblings (45 to 31 breaths per minute, P less than 0.001). Arousal occurred during 25% of the hypoxic challenges in the controls and apneic infants but was not seen in the siblings of SIDS (control vs siblings P less than 0.08, apneic vs siblings P less than 0.05). With inhalation of 4% CO2 there was a similar increase in estimated ventilation among the three groups. Arousal occurred 33% of the time in all three groups. Our findings show that, after 5 weeks of age, siblings of SIDS have a normal response to hypercapnea but respond to mild hypoxia with periodic breathing.

Does gastric acid protect the preterm infant from bacteria in unheated human milk

Although preterm mothers milk has greater nutritional and anti-infective properties than donor milk, it may be highly contaminated with bacteria. We therefore asked three questions: what is the fate of these bacteria in the preterm infants stomach, is gastric pH important, and what factors affect gastric pH? pH, colony count and bacterial identification were performed on the milk and on serial gastric aspirates in 20 preterm infants on 25 occasions. Seventeen milk samples grew bacteria, five potentially pathogenic and 12 non-pathogenic. Twelve of 25 prefeeding gastric samples were sterile, but following the feeding all the samples grew non-pathogenic bacteria and 70% grew potential pathogens. With time pH decreased and by 2-h samples with pH less than 3.5 had no bacterial growth; Candida albicans still flourished in a low pH (mean 2.8). We concluded that a low gastric pH may be more important than the bacterial count of the milk. In a second study, 91 serial gastric pH measurements were made on 12 preterm infants. pH tended to decrease with increasing age and was significantly lower in infants fed exclusively human milk (2.7 vs. 3.6; human milk versus formula P less than 0.02) We speculate that human milk may influence gastric acid production and thus protect the preterm infant from bacteria in the milk.

1598 MUSCLE RELAXANTS-A POTENTIAL DANGER TO INFANTS AT RISK FOR INTRAVENTRICULAR HEMORHAGE

Goldberg recently reported an increased incidence of intraventricular hemorrhage(IVH) in infants receiving muscle relaxants(MR). The mechanism is unknown. We studied 11 infants (BW 850-2800gm) before and during administration of curare or pancuronium. The effects of an increase of 4cm. peak inspiratory pressure (↑PIP) and of leg raising(LR) were tested. Intracranial pressure(ICP) was measured. Cerebral blood flow (CBF) was assessed by a doppler technique and expressed as pulsatility index (PI=systolic-diastolic/systolic) (Bada). Our results (Mean±SD):During MR, PI decreased, consistent with an increase in apparent CBF. There was no significant change in ICP due to MR alone. However, there was a significantly greater increase in ICP during ↑PIP and LR. Both observations suggest a loss of autoregulation during MR.We conclude, muscle relaxants affect cerebrovascular dqnamics and may be dangerous in infants at risk for IVH, particularly when high PIP is required.

190 NO BURNS, NO GRADIENT - PULSE OXIMETRY, AN ALTERNATIVE TO TRANSCUTANEOUS PO 2

Continuous monitoring of oxygenation in sick newborns is essential. However, transcutaneous PO2 (tcPO2) measurements have limitations. The extremely immature infant cannot tolerate a heated electrode. Older infants, and infants with BPD have large and unpredictable skin-arterial gradients. We report pulse oximetry as a technique for continuous, non-invasive measurement of arterial oxygen saturation (SaO2). We studied 20 infants, gestational ages 28–40 weeks, ages 1–49 days. Fetal hemoglobin (Hb) determinations were made on all infants and ranged from 5–100%. SaO2 readings from the Nellcor Pulse Oximeter were compared to the SaO2 measured with an IL282 CO-Oximeter on simultaneously obtained arterial blood samples. The method of Cornellisen (Clin. Chem., 1983) was used to correct for the fictitiously elevated carboxyhemoglobin levels caused by the presence of fetal Hb. The figure shows the close correlation for the 121 samples (Y=24.45+0.72X, r=.89.). The correlation was equally good for the 3 infants greater than 1 month of age with BPD. We conclude that the pulse oximeter provides an accurate, non-invasive alternative to tcPO2 monitoring, and overcomes some of the limitations previously encountered.

745 IS THE CONCEPT OF A “SAFE” BACTERIAL COUNT FOR RAW HUMAN MILK ACADEMIC?

To determine the fate of bacteria in human milk, we obtained serial cultures of gastric contents in 20 well preterm infants (BW:1200±91g, GA:29±1 wk, age:27±4 days, mean±SE). Eleven infants received fresh frozen maternal milk (FMM), 7 received donor milk (DM), and 2 received formula (F). Using sterile technique, samples were obtained via a gastric tube for colony count and identification before, and at 0, 0.5, 1, 1.5, and 2 hrs after a feeding. pH was tested with Hydrion tape. Three of 11 FMM, 6 of 7 DM, and both F samples were sterile, the rest were contaminated with skin bacteria (1-290 × 103/ml). At time 0, 12 of 23 gastric samples were sterile, 4 grew skin bacteria, 7, pathogens, and 4, Candida. Bacterial growth was related to time and pH (Fig). No bacteria grew if pH was ≤3.5 but Candida growth was unaffected by pH.Our findings indicate that the ability to generate an acid pH is an important factor in the preterm infants ability to suppress bacterial growth and that the debate about a “safe” bacterial count for raw human milk for the well preterm infant may indeed be academic.