Chronic night cough and asthma severity in children with stable asthma.

The relationship between night cough and other indices of asthma severity was studied in 21 children with clinically stable asthma and persistent night cough. Overnight cough was quantified and related to symptom scores, oxygen saturation (SaO2) during sleep, evening and morning peak flow recordings and daytime tests of lung function. In the index group the median number of coughing episodes was 23 (range 1-158). Only 4 children had counts of < 10 overnight, similar to the comparison group of 12 children all of whom had counts of < 10. There was a trend towards the association of overnight cough with reduced evening peak flow (r = -0.407, P = 0.07) and reduced SaO2 (r = -0.36, P = 0.10). Abnormalities in daytime tests of lung function were observed in 13 children. There was no relationship between night cough and daytime indices of lung function abnormality although children with more severe daytime abnormalities also had significant night cough. Conversely, five children with chronic night cough had normal daytime function. Conclusion. Night-time cough in children with asthma is not simply a reflection of daytime lung function status, whereas, overnight SaO2 correlates well. Other factors need to be explored to explain the variability of night-time cough in these children.

Use of the 1 tuberculin unit (TU) Mantoux test in the assessment of tuberculous infection in children following neonatal BCG vaccination.

BACKGROUND: BCG vaccination alters the response to tuberculin testing and influences the potential validity of the Heaf test in the diagnosis of tuberculosis. This study used a purified protein derivative 1 tuberculin unit (TU) Mantoux test with a cut off of 5 mm induration as an indicator of tuberculous infection in high risk children to determine whether this would distinguish infection from previous neonatal BCG vaccination. METHODS: Children at high risk of tuberculosis on chest radiography, Heaf test, or contact history who had been screened in the contact tracing clinic and referred for further assessment were included in the study. After clinical examination, chest radiography, and Mantoux testing they were assigned to three groups (tuberculous disease, chemoprophylaxis, or no treatment) and followed up for 6-24 months in the outpatient clinic and subsequently by postal questionnaire. RESULTS: Comparison of the Heaf and Mantoux tests showed a difference in the results with 82% of cases positive by the Heaf test and 59% positive by the Mantoux test. Using the Mantoux test result in combination with clinical and radiographic findings 194 children were allocated to the three groups as follows: primary tuberculosis (5), chemoprophylaxis (101), no treatment (88). During follow up for a mean (range) time of 46 (11-102) months four additional cases received treatment for primary tuberculosis, two in the chemoprophylaxis group and two in the untreated group. CONCLUSIONS: The use of the 1 TU Mantoux test after neonatal BCG vaccination reduced the number of children receiving treatment from 129 to 93-that is, by 36%. Although the numbers are small, there was no increase in the later development of tuberculosis.

The Hering-Breuer deflationary reflex in the newborn infant.

Initial observations on healthy term infants using the forced partial expiratory flow-volume technique with an inflatable jacket suggested that this technique was stimulating the Hering-Breuer deflationary reflex, a reflex which has not been systematically studied in man. To investigate this fully, esophageal pressure, jacket pressure, flow and volume at the mouth were recorded during the forced partial expiratory flow-volume maneuver on 10 infants (mean age, 3.1 days; birth weight, 3533 g; gestation, 39.8 weeks). A total of 186 measurements were performed at different points in the respiratory cycle. In 159 (85%) recordings inspiratory effort was evident with a fall in esophageal pressure within 166 msec; in some cases this occurred before the jacket was fully inflated. This was associated with a reduction of 23.4 cm H2O in mean intrathoracic pressure, which was 2.5 times that occurring during normal tidal breathing. In the remaining 27 measurements a plateau pressure was associated with closure of the upper airway. When the squeeze was applied at low lung volumes (end-expiration) the inspiratory effort occurred significantly earlier (133 msec) and stronger (reducing peak intrathoracic pressure to 15.8 cm H2O) than when applied at end-inspiration (181 msec with a reduction in intrathoracic pressure to 25.2 cm H2O). The observed inspiratory response was highly consistent, representing the deflationary reflex as described by Hering and Breuer in 1868. The stronger and more rapid onset of inspiration at low lung volume supports the claim made by Breuer that it has a protective role on functional residual capacity (FRC) in young infants.

Dynamic lung inflation during high frequency oscillation in neonates.

The effects of high frequency oscillation (HFO) on dynamic lung inflation were examined in 22 neonates ventilated for respiratory disease. HFO was combined with conventional ventilation and a series of frequencies from 2-25 Hz was tested. Dynamic lung inflation was measured using a jacket plethysmograph which was converted to a measure of alveolar pressure using the compliance of the respiratory system obtained during conventional ventilation. The results showed an increase in dynamic lung inflation with frequency such that volume increased by 0.4 ml for each increase of 10 Hz. Alveolar pressure increased by 1.2 cm H2O for each increase of 10 Hz. Dynamic lung inflation also increased with increased volumes of oscillation.

The effects of mid-trimester amniocentesis on lung function in the neonatal period.

Lung function tests were carried out on 39 healthy full term babies born after pregnancies subjected to mid-trimester amniocentesis. The results were compared to 42 babies born after normal pregnancies. There were no significant differences in gestational age, birth weight, thoracic gas volume or crying vital capacity. Babies subjected to amniocentesis had a significantly lower dynamic compliance (6.96 ml/cm H2O vs. 8.60 ml/cm H2O) and tended to have higher resistance compared to controls (52.8 cm H2O/l/s vs. 37.3 cm H2O/l/s). This provides further evidence that mid-trimester amniocentesis does have an adverse effect on lung growth and development.

Measurement of tidal lung volumes in neonates during high-frequency oscillation.

High-frequency oscillation (HFO) has been used clinically to ventilate infants with respiratory distress. However, there are problems in monitoring the effects on the respiratory system and in particular in measuring the volumes delivered; this is important information in terms of safety and mechanisms of action of HFO. We have validated two sizes of respiratory jacket for measuring oscillatory volume changes of 0.25-5 ml at frequencies of 2-25 Hz, the volume delivered from a purpose-built oscillator having first been validated. Different combinations of volume and frequencies were then oscillated into each jacket, while it was being worn by a well preterm baby. Studies were performed with each jacket on five babies with weights between 0.82 and 1.86 kg. The results showed that at any given frequency there was a linear relationship between the pressure oscillations measured from a side port of the jacket and the delivered volume. Both jackets showed the same pattern of frequency response, overreading at less than 10 Hz and underreading at 10-25 Hz. When appropriately calibrated, the respiratory jacket can be used as a non-invasive method of measuring volumes delivered by HFO.

Asthma severity at night during recovery from an acute asthmatic attack.

This study was undertaken to investigate the severity of night time asthma in children in hospital recovering from an acute attack of asthma. Twenty two children aged 5-14 years were studied. Coughing 'epochs' overnight varied from one to 156 (median 39.5) and mean overnight arterial oxygen saturation (Sao2) from 82 to 98% (mean 91.3). Log values for cough showed a correlation with Sao2. An Sao2 of less than 90% was invariably associated with coughing but Sao2 above 95% did not preclude cough. Peak flow measured in the morning or evening correlated with Sao2 but not with log cough, and clinical examination scores showed no correlation with overnight measurements. Night time Sao2 correlated better with daytime tests of lung function than log cough. In general, night time indices of severity reflected daytime pulmonary function status but night cough was sometimes prominent in less severely affected cases. At the time of discharge, clinical indices of severity underestimated the degree of functional impairment at night.

Effect of controlled release salbutamol on nocturnal cough in asthma.

Sixteen asthmatic children completed a double blind placebo controlled crossover study of controlled release salbutamol (CRS) to assess its efficacy in controlling night time cough. Children with asthma were enrolled into the study on the basis of a history of persistent cough confirmed by two overnight tape recordings at home. Outcome was measured by two overnight tapes on each medication. Other treatment was unaffected. There was no significant fall in cough counts on CRS. Median scores were 14.5 and 12.0 coughing episodes per night for CRS and placebo respectively. Mean overnight oxygen saturation was identical in both treatment periods but morning peak flow showed a trend towards improvement on CRS. Treatment with CRS does not have a significant effect in control of night cough although it may improve objective measurements of lung function.

Combined conventional ventilation with high frequency oscillation in neonates.

Combined high frequency oscillation (HFO) with conventional ventilation was used on a group of 12 ventilator dependent neonates in order to investigate the frequency response of the respiratory system to HFO. Pressure oscillations were measured at the airway opening with a transducer and volume oscillations at the chest wall using a calibrated respiratory jacket. Pressure oscillations increased with increasing frequency but the oscillating volumes showed a variable pattern with maximum oscillating volumes of up to 4 ml/kg. Three babies showed no change in volume between 2-25 Hz, 3 babies showed increasing volumes up to 25 Hz and the remainder showed a maximum volume (or resonant frequency) at 15-20 Hz. Oscillating volumes were higher when the conventional ventilator was in the expiratory phase. The differences in frequency response were unrelated to severity of lung disease, birth weight, age at testing, or size of the endotracheal (ET) tube. Local factors in the ET tube and large airways may account for some of the observed differences.

Acute abdominal pain and appendicitis in north east Thailand.

In a survey of emergency admissions to hospital in rural Thailand, acute appendicitis was the commonest cause of acute abdominal pain. Estimates of the incidence of appendicitis, in two series comprising a total of 356 patients, at 3.2 and 3.7 per 10,000 population per year, were relatively high compared with reports from other warm climate countries. In comparison with 1825 cases in studies sponsored by the Organisation Mondiale de Gastroenterologie (OMGE), Thai patients with acute appendicitis were older, presented late and experienced more complications than those in 14 other countries. In Khon Kaen only 2-3% of the cases were children aged 0-9 years, compared with 9-26% in the OMGE series. In patients admitted to hospital with acute abdominal pain in Thailand, acute appendicitis was diagnosed more often than non-specific abdominal pain. The converse was true in the OMGE series. This may reflect the longer distances travelled to hospital by many patients and delays between onset of symptoms and admission to hospital. Acute appendicitis was the commonest definitive diagnosis in both series. This survey indicates that relatively high rates of acute appendicitis may occur in populations eating traditional diets. The results are consistent with the recently described hypothesis of an infective aetiology and increases in appendicitis rates may be expected in people born since the introduction of improvements in environmental sanitation. Further studies are needed to examine trends in the incidence of appendicitis in populations eating traditional diets with both high and low fibre content and to investigate the significance of changing social and environmental factors.

Validity of forced expiratory flow volume loops in neonates.

It is claimed that suddenly squeezing a newborn baby's trunk with a pressure of 3-4 kPa produces a flow volume curve that can be used to measure the function of the small airways. If the squeeze is applied during expiration rather than at the end of inspiration, however, anomalous results may be obtained. One possible explanation is that the babies are limiting expiratory flow by making inspiratory efforts in response to the applied external pressure. The response of 10 healthy term neonates to forced expiration was studied by using an oesophageal balloon. The squeeze was provided by an inflatable jacket, and measurements of oesophageal pressure and jacket pressure were recorded, as well as flow and volume changes at the mouth. Two hundred and twenty one squeezes were performed at different points in the respiratory cycle. In 188 squeezes an inspiratory effort was evident before the oesophageal pressure reached a plateau (mean time to peak pressure = 155 ms). For the remaining squeezes a plateau pressure was associated with closure or narrowing of the upper airway in most of the babies. When the squeeze was applied at low lung volumes the inspiratory effort was significantly earlier and stronger than around end inspiration. Thus a baby makes a reflex inspiratory response to chest compression that may interfere with the measurement of airway function when this technique is used.

Endotracheal resuscitation of preterm infants at birth.

The adequacy of initial ventilation in 21 preterm babies (25-36 weeks' gestation), who required endotracheal intubation and positive pressure ventilation, were studied. Pressure and flow were measured at the proximal end of the endotracheal intubation tube and expiratory volume calculated from the flow trace. The results were compared with those from a group of 26 term infants who also required resuscitation. Five of 21 preterm babies (24%) had adequate tidal ventilation with the first inflation. This rose to seven of 21 (33%) by the third inflation. This was significantly less than the results in the term infants (chi 2 = 4.38 p less than 0.05). Respiratory reflex responses to resuscitation were seen in 41% of inflations in preterm and 56% of inflations in term infants. There was a significant correlation between reflex activity and adequate ventilation in the preterm group (chi 2 = 11.83, p less than 0.001) but not in the term group (chi 2 = 0.212, p = NS). No correlation was seen between initial ventilation and outcome.

A simple method of face mask resuscitation at birth.

Twenty two infants were resuscitated at birth using a face mask connected to an oxygen supply from a conventional resuscitaire. Intermittent finger occlusion provided the positive pressure within the mask. This method was apparently at least as effective as the best bag and mask systems and was convenient to use.