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The basic principles and indications of high frequency oscillatory ventilation are presented. The authors have used this technics in more than 400 neonates with respiratory failure. High frequency oscillatory ventilation appears as a simple, efficient and safe method of ventilation in the treatment of neonatal respiratory distress.

Neonatal mortality and morbidity were reported over a 4-yr period from 1986-1989 in premature infants weighing less than 1,500 g, 278 of whom were born in the same obstetrico-neonatal unit. Total mortality was 15%, and was higher in premature infants weighing less than 1,000 g (38%) and lower if the gestational age was greater than 27 wk. Mortality was lower in small for gestational age (SGA) infants than in appropriate for gestational age (AGA) infants (5% vs 19%, P less than 0.001), and lower in inborn babies than in outborn (12% vs 19%, P less than 0.02) but only in neonates weighing less than 1,000 g. Neonatal morbidity was mainly due to hyaline membrane disease and cerebral haemorrhage. The incidence of broncho-pulmonary dysplasia was low (4%). These results indicate that gestational age, birth weight and place of delivery play a role in mortality and morbidity in very low birth weight premature infants.

The outcome of 60 premature infants weighing less than 1,000 g at birth and consecutively born during the years 1986 to 1988 is reported. Forty-two (70%) of them were inborn. The overall mortality rate was 42%, but only 26% in the inborn group instead of 78% in the outborn group (P less than 0.001). The mortality rate was higher for the appropriate for gestational age infants (56%) than for the growth retarded infants (14%, P less than 0.01). The main neonatal problems were the following: hyaline membrane disease (63%), patent ductus arteriosus (7%), bronchopulmonary dysplasia (8%), necrotizing enterocolitis (15%), intraventricular hemorrhages (45%) and periventricular leukomalacia (12%). Twenty percent (7/35) of the surviving infants showed abnormal neurodevelopmental outcome, with only one (3%) having major handicap. No correlation was found between gestational age and neuro-developmental outcome.

In 2 very low birth weight infants, a Nelcor 100 pulse oximeter was used during surgery. These 2 babies were anesthetized during the first 3 weeks of life, one for patent ductus arteriosus ligation and the other for ventriculo-peritoneal derivation. SaO2 was maintained between 85-95% in the straight portion of hemoglobin dissociation curves, where PaO2 values are from 7 to 10 KPal. During anesthesia, FiO2 was kept between 21 and 30%. Oximeters which have a fast response time seem to be a useful tool for monitoring blood oxygenation when it is difficult to estimate normoxia but very important to avoid hypoxia or over-oxygenation.

Survival rate of 96 low-birth-weight infants less than 32 weeks post-conceptional age at birth was studied in relation with the mode of delivery. Twenty-two infants were delivered by elective cesarean section because of abnormalities during pregnancy with 3 neonatal deaths. Seventy-four infants were born after untreatable premature onset of labor with 9 intrapartum and 7 neonatal deaths. Poor prognosis was associated with gestational age (less than 29 weeks), non cephalic vaginal delivery and multiple births. In these cases, cesarean section should be discussed.

78 cesarean sections (CS) were performed before 32 weeks of gestation over a period of six years in a obstetric clinic; 91 premature infants were born; the rate of CS at this period of time represented 0,47% of total birth. 84 premature infants were transferred to the neonatal unit located in the same clinic; 3 were dead in utero and 4 just after delivery. 69 infants survived (78%) but 6 had severe sequelae (spastic diplegia, epilepsy and RLF) at one year of age and 7 had minor sequelae.

The authors describe the methodology of high frequency ventilation in the newborn infant. Ventilation by oscillator (HFO) actually represents the best method for ventilation in newborn infants; the rate of ventilation is between 15 and 25 Hz/min. They report their experience of HFO use for the treatment of hyaline membrane disease in newborns.

Thirty-three observations of late-onset neonatal hypocalcemia were reviewed retrospectively. Their etiological, clinical and biological features were consistent with a transient congenital hypoparathyroidism, associated with a materno-foetal vitamin D deficiency. 1 alpha-hydroxycholecalciferol was used for rapid correction of calcemia and proved to be satisfactorily metabolized after its oral administration.

In a retrospective study of 83 preterm newborns of 32 weeks of gestation or less, isolated periventricular leukomalacia was found in 7 cases (8.4%). Ultrasonographic diagnosis was made in all cases during the first 3 days of life and cystic lesions always occurred during the first 40 days. Five of the 7 newborns suffered from in utero asphyxia, 4 had an Apgar score below 5 at 5 min, and only 4 presented a respiratory distress syndrome. Thus the diagnosis of periventricular leukomalacia can be established early by ultrasonography. In utero asphyxia seems to be a critical determinant of ischaemic brain lesions.

Twenty-nine newborn infants with diaphragmatic hernia have been received in a neonatal intensive care unit over a seven year period. In three cases, clinical signs appeared after the first day: they all survived. Six infants died before surgery: five of them had major pulmonary hypoplasia. Surgery was performed in twenty cases: nine of these infants died. Death occurred during the first twelve post-surgical hours in six cases with major pulmonary hypoplasia. Fourteen infants were followed from 6 to 24 months; two developed post-anoxic hydrocephaly with poor neurological development in one case. A pH above 7.1 and an adequate hemodynamic status obtained before surgery are simple criteria of a good prognosis. When these criteria are not obtained, prognosis is poor as they are in favor of major pulmonary hypoplasia.