Nils W Svenningsen

Airway and body surface sensors for triggering in neonatal ventilation

Failure of neonatal patient triggered ventilation may reflect a delay in delivery of flow relative to the inspiratory effort of the infant. Transmission of diaphragmatic contraction to the sensor site (patient delay) and further transmission to and within the sensing device (device delay) both contribute to the delay in triggering. Patient and device delays were studied for different sensing systems in 36 infants, 24 of whom were intubated. Device delay was long (<40 ms) with a conventional apnoea monitor compared with sensors placed at the airway opening (2 ms), the inspiratory (12 ms) and expiratory (3 ms) pressure transducers of the ventilator, the Graseby capsule (8 ms), strain gauges (3 ms) and oesophageal pressure (6 ms). In near normal infants, the sum of patient and device delays for the latter sensors was less than 20 ms and a minor component of the total delay. However, in severe lung disease the total delay may be more than 100ms even for airway sensors.

Changing trend in perinatal management and outcome of extremely low birthweight (ELBW) infants

Perinatal care of the extremely preterm and low birthweight (ELBW) infant is founded on basic principles of physiology and knowledge about the prevailing pathophysiological mechanisms. New therapies in clinical care are usually introduced non‐uniformly, so more often there is a gradual rather than a sudden change in the development of perinatal care, conceivably involving also an important learning process. This was confirmed in an evaluation of respiratory care for ELBW infants (n = 325) over a 9‐year period (1986–1994). Although birthweight (mean 815 g) and degree of immaturity at birth (mean 26.7 weeks of gestation) did not change over the years, our trend analysis showed that the survival rate increased from 47% to 70% (p < 0.04) and the percentage of survivors without bronchopulmonary dysplasia and/or major intracranial haemorrhages (ICH grades 3 and 4) increased from 67% to 87% (p < 0.006). We suggest that besides medical treatment per se, refinement and tuning of nursing and medical care procedures will also affect the total outcome of ELBW infants.

Measurement of Ventilation and Respiratory Mechanics during Continuous Positive Airway Pressure (CPAP) Treatment in Infants

ABSTRACT. A new method has been evaluated for measuring ventilation and lung mechanics in spontaneously breathing infants by means of a face chamber. Airway flow is measured with a pneumotachograph inserted between the face chamber and a stable pressure source. Oesophageal pressure is measured via a water‐filled oesophageal catheter. The method is suitable for use in conjunction with continuous positive airway pressure (CPAP) treatment in neonatal intensive care. A flat frequency response curve up to 15 Hz for the two measuring systems (i.e., airway flow and oesophageal pressure), and a time shift between the two respective signals of less than 2 msec are prerequisites for correct evaluation of respiratory mechanics. In preterm infants with chest distortion, the inhomogeneity of pleural pressure affects the significance of resistance and compliance values, as calculated from oesophageal pressure. Supra‐diaphragmatic pressure variations reflect the resistive and elastic load on the diaphragm exerted by the lungs and thorax. Thus, oesophageal pressure is still useful in studies of respiratory mechanics in preterm infants.

EARLY DETECTION OF PRESCHOOL HEALTH PROBLEMS—ROLE OF PERINATAL RISK FACTORS

Abstract. To evaluate a perinatal riskgrouping system, 1262 4‐year‐old children went through a comprehensive health examination. A total of 41.5% of the newborns were included in the wide criteria of risk, which were more common among boys and among children of the youngest and oldest mothers. Among the 4‐year‐old, the frequency of significant physical health problem was 15.8%, including 10.1% visual disturbances and 2% neurological disorders. In some combinations of riskgroups and later health problems there were statistically significant correlations, e.g. regarding prematurity and cerebral irritation vs. cerebral palsy, hut not sufficient to serve its purpose as a screening instrument. Even the accumulation of especially serious events in the perinatal period gave no clue to later neurological disorders. The addition of low socioeconomic status as a perinatal risk did not influence the outcome either. The reasons for the weak correlation between perinatal risk factors and later outcome of health disorders and handicaps are discussed, and it is concluded that to detect children with health problems, there seems to he no acceptable alternative to a comprehensive health surveillance as part of a general health service programme of all children, including clinical examinations and screening procedures by well trained personnel.

THROMBOCYTOPENIA AFTER RUBELLA (REPORT OF TWO CASES).

Purpura thrombocytopenica may occur as a complication of a great number of infectious diseases [4, 12, 14, 191. In rubella this has been reported only in about 35 cases [l, 5, 6, 9, 10, 13, 14, 16, 17, 18, 191. In the new-born baby thrombocytopenia has occurred after rubella during the first months of pregnancy [2]. As i~ complication of rubella also a few cases of encephalitis have been reported [5, 171. In 1963, there was an epidemic of rubella in Halsingborg, and two cases of verified rubella complicated by serious thrombocytopenia were treated in the Childrens Hospital.

Preceding surfactant treatment does not protect against lung volutrauma at birth |[dagger]| 1518

Manual ventilation with a few large breaths at birth may cause lung injury in immature lambs. The severity of injury was related to the size of lung inflations (8-32 ml/kg), but even modest inflations before surfactant (S) caused a significant lung function impairment (Pediatr Res 1996;39:326A). We now studied if preceding S treatment would protect the lungs against this injury, and if not, for how long after S the lungs would be sensitive to deep inflations. Twelve lambs of gestational age 127 days were randomized to four different treatments: 1) Five inflations of 16 ml/kg at birth immediately followed by S, 2) S at birth immediately followed by inflations, 3) S at birth, inflations at 10 min, 4) S at birth, inflations at 60 min. Lung mechanics was repeatedly measured during 4 hours of pressure limited mechanical ventilation. Significantly higher airway pressures were generated by inflations at birth (groups 1 and 2) than when inflations were postponed(groups 3 and 4). Static compliance (see figure) and inspiratory capacity remained low throughout the study in groups 1 and 2. We conclude that deep inflations at birth caused lung function impairment whether they were preceded by S or not, but already at 10 min inflations of the same size caused no apparent harm. Ventilation of preterm infants may need to be very tender during the first few minutes of life.

Lung Trauma From Five Moderately Large Manual Inflations Immediately After Surfactant Instillation in Newborn Immature Lambs † 1678

Lung Trauma From Five Moderately Large Manual Inflations Immediately After Surfactant Instillation in Newborn Immature Lambs † 1678

Outcome of Severe Respiratory Insufficiency in Near Term Infants Who Failed on Conventional Treatment

Outcome of Severe Respiratory Insufficiency in Near Term Infants Who Failed on Conventional Treatment

Cerebral Glucose Metabolism in Term Newborn Infants with Hypoxic Ischemic Encephalopathy (HIE) - A Positron Emission Tomography Study (PET)

Cerebral Glucose Metabolism in Term Newborn Infants with Hypoxic Ischemic Encephalopathy (HIE) - A Positron Emission Tomography Study (PET)

LUNG INJURY CAUSED BY NEONATAL RESUSCITATION OF IMMATURE LAMBS - RELATION TO VOLUME OF LUNG INFLATIONS. |[dagger]| 1942

We have previously shown that manual ventilation with a few large breaths(35-40 ml/kg) at birth compromises the effect of subsequent surfactant treatment in immature lambs [Acta Anaesthesiol Scand 1995;39(suppl 105):153]. We now studied if also smaller lung inflations would damage the surfactant-deficient lung. Lambs with gestational age 126-128 days were randomized to five different treatment schedules with Curosurf (C) 200 mg/kg: 1) C mixed with lung liquid before birth, 2) C after birth, but before the first breath. and 3-5) five sustained lung inflations (8, 16 and 32 ml/kg, respectively) at birth, immediately followed by C. The lambs were then mechanically ventilated, and blood gases, lung volumes and deflation pressure-volume curves of the respiratory system were recorded regularly during 4 h. There was no significant difference in oxygenation between the groups, but the other lung function parameters indicated an increase in lung injury in relation to the volume of early lung inflations. The lambs given the smallest lung inflations (group 3), still had a 38% reduction of static compliance at 4 h as compared to lambs in group 1. We conclude that even modest inflations of surfactant-deficient lungs during resuscitation may cause significant lung injury. Figure