Biomedical subjects

M Hird

Publications and source records attributed to M Hird.

22 records · Page 2Linked to original sources

PubMed1991

Inflation time in mechanical ventilation of preterm neonates.

The importance of the preterm infant's inspiratory time in determining the optimum inflation time during mechanical ventilation was investigated. The optimum inflation time was defined as that which was most commonly associated with synchronous respiration and maximum minute volume. Twelve preterm infants were studied on 14 occasions. They were ventilated at rates of 60, 75, 90, 105 and 120 breaths/min, with an inspiratory: expiratory ratio of 1:1.2. These rates were chosen as they resulted in inflation times approximating to the spontaneous inspiratory time measured during a brief period of disconnection, on continuous positive airways pressure (CPAP), and greater than that measured on CPAP. Inspiratory time during disconnection was always shorter than that measured on CPAP (P less than 0.01). Synchrony was most commonly provoked and minute volume greatest at the shortest inflation time (P less than 0.01). We conclude fast ventilator rates are most efficacious for preterm neonates. As previously shown, this rate can be estimated by examining the standard reference range of rates in relation to gestational age.

Gestational Age↗

PubMed1990

Gas trapping during high frequency positive pressure ventilation using conventional ventilators.

Inspiratory and expiratory volumes were measured in 51 preterm infants with respiratory distress syndrome (RDS), when comparing two ventilator rates, 60 and 120 breaths/min. Gas trapping was not demonstrated at rates of 60, but in 11 infants at 120 breaths/min and this was more common in the paralysed infants and those more mature than 31 weeks gestational age (P less than 0.05). The median change in functional residual capacity resulting from gas trapping was 3.8 ml/kg. We conclude rates of 120 breaths/min can be used in the majority of non-paralysed infants without gas trapping but should be avoided in paralysed infants more mature than 31 weeks.

High-Frequency Ventilation↗

PubMed1990

Listeriosis revisited: the role of the obstetrician.

The clinical course and outcome is described of three pregnancies complicated by listeriosis encountered during a 6-month period. All three ended in preterm labour characterized by the passage of meconium by the fetus. Two babies died in the early neonatal period and the third survived with neurological handicap. Although the diagnosis of listeriosis was made only after delivery, all the mothers had a pyrexial illness before delivery. A high index of suspicion is needed for the early detection and prompt treatment of this life-threatening perinatal infection. Effective advice concerning prevention of listeriosis by avoidance of high-risk foods must be given to women during pregnancy.

Adult↗

PubMed1989

Limitations of patient triggered ventilation in neonates.

The practicality of long term patient triggered ventilation using airflow changes was assessed in 22 infants with a median gestational age of 29 weeks (range 25-33 weeks). Inflation time during patient triggered ventilation was limited to 0.4 seconds or less. Initially it was associated with improvements in oxygenation in most infants. Patient triggered ventilation was maintained till final extubation in 13 of the infants without complications. Only one infant developed a pneumothorax, but in the remaining eight infants (who tended to be less mature (p less than 0.01) it had to be discontinued after only a few hours. Predictors of failure of patient triggered ventilation at one hour were both a lack of improvement in oxygenation, and a relatively slow triggering rate that was related to gestational age. We conclude that long term patient triggered ventilation is practical for preterm neonates, but only for those more mature than 28 weeks' gestational age.

Evaluation Studies as Topic↗