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Biomedical subjects

U M MacFadyen

Publications and source records attributed to U M MacFadyen.

30 records · Page 2Linked to original sources
PubMed1989

Sleep phase and gastro-oesophageal reflux in infants at possible risk of SIDS.

The association between gastro-oesophageal reflux and sleep state in 24 infants with confirmed or suspected gastro-oesophageal reflux was studied by monitoring both the pH in the lower oesophagus and polygraphic tracings made during sleep at night. Gastro-oesophageal reflux during the night was confirmed in 20 infants. Three hundred and sixteen precipitous drops of more than one unit of pH were recorded during the studies, 186 during periods of wakefulness. Of 130 drops in pH during sleep, 62 (48%) began during active sleep and 62 during indeterminate sleep. Of the latter, 56 (90%) were associated with brief gross body movements. Only five of the drops in pH (4%) began during quiet sleep. Gastro-oesophageal reflux stopped during active sleep on 56 occasions (43%), in indeterminate sleep in 62 (47%), and in quiet sleep in 12 (9%). Episodes of gastro-oesophageal reflux starting or ending in quiet sleep were uncommon. The occurrence of gastro-oesophageal reflux during active sleep may partly explain why reflux during sleep is a risk factor for pulmonary disease.

Esophagus↗
PubMed1989

Respiratory control in infants at increased risk for sudden infant death syndrome.

There is much debate relating to possible abnormalities in respiratory control mechanisms in infants considered at increased risk for sudden infant death syndrome (SIDS). The P0.1 occlusion technique was used to assess the central respiratory response to hyperoxic hypercapnia during quiet sleep in 21 normal infants, 13 siblings of SIDS victims, and 17 infants with apparent life threatening events. The slope of P0.1 plotted against carbon dioxide concentration increased exponentially with age, independent of body weight in each group. Birth weight has a significant effect on slope with a lower weight predisposing to a lower slope. Siblings as a group had a significantly lower slope at any given age than normal infants, whereas the infants who had had apparent life threatening events were not significantly different from the controls. As intragroup variation in both siblings and control groups greatly exceeded the significant intergroup differences observed, the technique cannot identify individual infants as belonging to one or other group.

Age Factors↗
PubMed1988

Discordant expression of the G syndrome in monozygotic twins.

We present clinical manifestations of monozygotic male twins with different degrees of expression of the G syndrome. Monozygosity was confirmed using DNA mini-satellite "fingerprint" analysis. The findings in these twins suggest that expression of the G syndrome can be strongly influenced by the prenatal developmental environment.

Abnormalities, Multiple↗
PubMed1988

Monitoring for central apnoea in infancy--limitations of single channel recordings.

Apparent central apnoea (absent breathing movements) detected by monitoring movement of the thoracic wall was compared with simultaneous detection by abdominal wall movement. Eighteen infants provided one or more 24 hour recording of heart rate (electrocardiography), thoracic respiration (transthoracic impedance), and abdominal wall movement (pressure sensitive capsule distortion). Detection of true apnoea, recognition of artefact, and measurement of the duration of true apnoea were all improved when two channels of respiratory monitoring were used in combination. We recommend that any study purporting to observe breathing patterns by indirect recording of respiratory movement will be more reliable if more than one channel of respiratory movements is recorded simultaneously. Further, in infants no estimation of duration of central apnoea can be made on the basis of either a transthoracic impedance record alone or an abdominal wall movement sensor alone. Comparison of findings among studies using different single channel recordings are unlikely to be meaningful.

Electrocardiography↗
PubMed1986

Sleep apnoea during upper respiratory infection and metabolic alkalosis in infancy.

Three to four hour polygraphic sleep studies were carried out in 10 infants, five with upper respiratory infection and five with metabolic alkalosis secondary to vomiting during and after recovery from illness. During upper respiratory infection, the main abnormality detected was brief (greater than 3 less than 6 seconds) or prolonged (greater than 6 seconds) attacks of obstructive apnoea. Other indices of apnoea were similar to recovery data. Gross body movements were also increased. In infants with metabolic alkalosis indices of central apnoea were significantly increased when compared with recovery or case control data. Prolonged (greater than 15 seconds) attacks of central apnoea and obstructive apnoea (greater than 6 seconds) were only observed during illness. Gross body movements and periodic breathing were also increased. These findings suggest that the functional consequences of apparently 'mild' illnesses in young infants may be greater than is generally suspected and perhaps relevant to mechanism(s) of death in sudden infant death syndrome.

Alkalosis↗
PubMed1986

'Near-miss' or 'near-myth' for sudden infant death syndrome? Clinical observations on 57 infants.

A clinical approach to infants who may have 'nearly missed' Sudden Infant Death Syndrome (SIDS) is suggested as appropriate whether or not the eventual conclusion is that there is no connection between these surviving infants and those who die of SIDS. A non-restrictive investigative approach has been applied to 57 infants with episodes causing similar levels of alarm and recourse to medical aid but not exclusively having documented apnoea or need for cardiopulmonary resuscitation. Similarities among patients in past history, recent minor symptoms, modes of presentation and positive investigations support the concept that they may show a common response to a variety of pathophysiologic stresses. Epidemiological similarities to SIDS cases support the suggestion that SIDS may be the end-stage inadequate response to such stresses. Future studies should address the reasons for 'inappropriate' collapse, its treatment and prevention and be alert to any resultant effect upon the incidence of SIDS or further evidence of a link between the conditions.

England↗
PubMed1985

Sleep apnoea in infancy.

Serial polygraphic sleep studies were carried out in 86 index infants (33 'symptomatic', 24 siblings of infants with the sudden infant death syndrome (SIDS), 29 'near-miss' for SIDS) and 11 healthy controls. Brief (greater than or equal to 3 less than 6 sec) or prolonged (greater than or equal to 6 sec) obstructive apnoea was observed only in index caes, and coincided with symptoms due to associated illnesses (usually respiratory). Their prevalence was comparable in 'symptomatic' and 'near-miss' groups--39% and 35% respectively. Prolonged (greater than or equal to 20 sec) central apnoea was seen only in pre-term 'near-miss' infants. Dips in transcutaneous oxygen tension greater than or equal to 15 mmHg occurred during sleep in 17% of 'symptomatic' infants and 19% of 'near-miss' cases, usually in association with obstructive or central apnoea. Diminution or disappearance of these abnormalities following clinical recovery from 'minor' illnesses suggested that they were the result of such illnesses.

Electrocardiography↗
PubMed1984

Home monitoring for central apnoea.

Between July 1978 and December 1981, 64 infants thought to be at increased risk from sudden infant death syndrome (SIDS) were monitored at home for central apnoea. Twenty four of the infants had had a 'near miss' episode at age, median (range), 6 (1 to 33) weeks, and of these infants 22 had had 335 alarms for apnoea by age 6 months. Stimulation by shaking was carried out on 38 occasions and bag and mask resuscitation on one. The remaining 40 infants were siblings of SIDS victims and of these, 35 were monitored from age 1 week (usually after discharge home). Thirty four of the SIDS siblings had had 573 alarms for apnoea by age 6 months: stimulation by shaking was carried out on 32 occasions and bag and mask resuscitation on one. The duration of home monitoring was, median (range), 34 (8 to 87) weeks for 'near miss' infants and 45 (12 to 70) weeks for SIDS siblings. All infants survived. As part of an over all support system monitors were accepted and greatly appreciated by most parents, especially those with previous experience of SIDS. Home monitoring was practicable but the commitment in time and expertise was great and objective benefits to the infant remain unproved.

Apnea↗
PubMed1983

Gastro-oesophageal reflux in near-miss sudden infant death syndrome or suspected recurrent aspiration.

We have compared barium swallow with a radionuclide gastro-oesophageal scintigraphy (milk scan) method of detecting gastro-oesophageal reflux in 26 infants. In 17 cases, presenting as near miss sudden infant death syndrome, reflux was detected in 2 by barium swallow and in 8 by scintigraphy. In the remaining 9 infants with suspected pulmonary aspiration, reflux was demonstrated by barium swallow in 2 and by scintigraphy in four. Aspiration after gastro-oesophageal reflux was demonstrated only by the radionuclide scan. The feasibility of recording physiological variables during periods of reflux was confirmed.

Female↗
PubMedDate not supplied

Observations on the limitations of two apnea/respiration monitors commonly used in the home.

The performance of two types of respiration monitor was studied with regard to detection of central apnea and individual breaths. Each monitor detected central apnea more frequently than routine intermittent nursing observation. Both false alarms, when the monitor failed to detect breathing movements (false positive for apnea), and false respiration signals, when the monitor failed to detect the absence of breathing movements (false negative for apnea) were found. The latter sometimes prevented alarms. It was found that a trial period of monitoring under the controlled conditions described permitted adjustments to be made which eliminated or minimized these sources of error. This should be considered when the monitors are issued for use in the home. It is important that persons issuing the monitors be aware of their limitations.

Apnea↗