- Email: [email protected]
The response to tube breathing in preterm infants with apnoea
108
Group
Cases Preterm controls ft-pccontrols ft-agecontrols
Pattern Breathing pause ,4s,< 15s
Breathing pause 315s
Combined pause
Uninterpretable flow
No airflow
Continuous airflow
Total number
259.2 73.7
60.6 1.6
3.3 0.0
132.0 5.4
22.1 1.0
42.5 17.7
519.7 99.4
35.1
1.3
5.8
3.7
2.5
1.5
49.9
5.7
0.0
0.0
0.0
0.0
0.0
5.7
The results show that a considerable proportion of hypoxaemic episodes occurs despite continuous airflow. This is true not only for the cases but also for the preterm controls. However, this pattern almost never occurs in the full-term controls. The pathophysiology of this pattern warrants further investigation.
The response to tube breathing in preterm infants with apnoea. C.J. Upton, A.D. Milner and G.M.
Stokes, Nottingham City Hospital, Nottingham, U.K. We have described a method of assessing respiratory control in term infants, by measuring their ventilatory response to added external dead spaces, and comparing this to an “expected” value calculated from the volume of the added tube [ 11.This study was designed to assess this response in preterm infants and to analyse the effects of post-natal and post-conceptual age and apnoea frequency. Twenty-seven preterm infants, median birth weight 1.14 kg and gestation 29 weeks, were studied on 86 occasions. Polygraphic recordings were made to assess apnoea frequency. Baseline minute ventilation was measured using a reverse plethysmograph and face mask. A switch was then turned to incorporate a tube equivalent to two anatomical dead spaces into the circuit. After one minute to adjust to this stress, minute ventilation was again measured and the percentage of “expected” values calculated. Using regression analysis, there was a marked tendency for the response to improve with increasing post-conceptual and postnatal age. Mean % expected values increased from 73% at 26 weeks up to 104% at 36 weeks gestation (P< 0.0001). Infants with frequent apnoea did not respond differently; mean % expected values were 89% in 42 studies with < 2 apnoeas per hour and 92% in 44 studies with > 2 apnoeas per hour (NS). Although the respiratory adaptation of the most immature infants is poor, this study suggests that those infants with apnoea show no gross deficit in respiratory control, compared to those without apnoea. 1
Stokes, G.M. et al. (1986): Pediatric Pulmonol., 2,89-93.
Tricuspid
regurgitation
in the newborn:
Doppler
estimation
of pulmonary
artery pressure,
J.R.
Skinner, S. Hunter and E.N. Hey, Princess Mary Maternity Hospital, Newcastle upon Tyne, U.K. Buckground: Doppler ultrasonic measurement of tricupsid regurgitation (TR) can accurately predict pulmonary artery pressure. Doppler evidence of TR is common in healthy adults and older children, even though clinical evidence of TR is absent. In the newborn, clinical TR is associated with birth asphyxia and persistent pulmonary hypertension. Aims: (1) To establish the prevalence of tricuspid regurgitation as detected by Doppler ultrasound in healthy neonates. (2) To estimate pulmonary artery pressure from tricuspid regurgitation jet velocity by applying the Bernoulli equation and correlate with age over the first 3 days of life.
Group
Cases Preterm controls ft-pccontrols ft-agecontrols
Pattern Breathing pause ,4s,< 15s
Breathing pause 315s
Combined pause
Uninterpretable flow
No airflow
Continuous airflow
Total number
259.2 73.7
60.6 1.6
3.3 0.0
132.0 5.4
22.1 1.0
42.5 17.7
519.7 99.4
35.1
1.3
5.8
3.7
2.5
1.5
49.9
5.7
0.0
0.0
0.0
0.0
0.0
5.7
The results show that a considerable proportion of hypoxaemic episodes occurs despite continuous airflow. This is true not only for the cases but also for the preterm controls. However, this pattern almost never occurs in the full-term controls. The pathophysiology of this pattern warrants further investigation.
The response to tube breathing in preterm infants with apnoea. C.J. Upton, A.D. Milner and G.M.
Stokes, Nottingham City Hospital, Nottingham, U.K. We have described a method of assessing respiratory control in term infants, by measuring their ventilatory response to added external dead spaces, and comparing this to an “expected” value calculated from the volume of the added tube [ 11.This study was designed to assess this response in preterm infants and to analyse the effects of post-natal and post-conceptual age and apnoea frequency. Twenty-seven preterm infants, median birth weight 1.14 kg and gestation 29 weeks, were studied on 86 occasions. Polygraphic recordings were made to assess apnoea frequency. Baseline minute ventilation was measured using a reverse plethysmograph and face mask. A switch was then turned to incorporate a tube equivalent to two anatomical dead spaces into the circuit. After one minute to adjust to this stress, minute ventilation was again measured and the percentage of “expected” values calculated. Using regression analysis, there was a marked tendency for the response to improve with increasing post-conceptual and postnatal age. Mean % expected values increased from 73% at 26 weeks up to 104% at 36 weeks gestation (P< 0.0001). Infants with frequent apnoea did not respond differently; mean % expected values were 89% in 42 studies with < 2 apnoeas per hour and 92% in 44 studies with > 2 apnoeas per hour (NS). Although the respiratory adaptation of the most immature infants is poor, this study suggests that those infants with apnoea show no gross deficit in respiratory control, compared to those without apnoea. 1
Stokes, G.M. et al. (1986): Pediatric Pulmonol., 2,89-93.
Tricuspid
regurgitation
in the newborn:
Doppler
estimation
of pulmonary
artery pressure,
J.R.
Skinner, S. Hunter and E.N. Hey, Princess Mary Maternity Hospital, Newcastle upon Tyne, U.K. Buckground: Doppler ultrasonic measurement of tricupsid regurgitation (TR) can accurately predict pulmonary artery pressure. Doppler evidence of TR is common in healthy adults and older children, even though clinical evidence of TR is absent. In the newborn, clinical TR is associated with birth asphyxia and persistent pulmonary hypertension. Aims: (1) To establish the prevalence of tricuspid regurgitation as detected by Doppler ultrasound in healthy neonates. (2) To estimate pulmonary artery pressure from tricuspid regurgitation jet velocity by applying the Bernoulli equation and correlate with age over the first 3 days of life.