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Plethysmograph and interrupter resistance measurements in prematurely born young children
M R Thomas1, G F Rafferty, R Blowes
1Department of Child Health, 4th Floor Golden Jubilee Wing, King's College Hospital, Bessemer Road, London SE5 9RS, UK.
Insights
The interrupter technique (Rint) showed poor agreement with plethysmography (Raw) for measuring airway resistance in premature infants. Rint cannot replace plethysmography in this population.
Area of Science:
- Pediatric Pulmonology
- Respiratory Physiology
- Infant Lung Function Testing
Background:
- Airway obstruction assessment in premature infants often relies on plethysmography, necessitating sedation.
- The interrupter technique offers a non-sedation alternative but lacks extensive evaluation in infants under two years.
Purpose of the Study:
- To compare interrupter technique (Rint) results with plethysmographic measurements of airway resistance (Raw).
- To evaluate the utility of Rint as a substitute for plethysmography in young, prematurely born children.
Main Methods:
- A prospective study involving 30 prematurely born children (median gestational age 25-29 weeks).
- Airway resistance measured using total body plethysmography (Raw) and the MicroRint device.
- Measurements were taken both at baseline and after salbutamol administration in sedated infants.
Main Results:
- Baseline Rint values were significantly higher than Raw values (p = 0.006).
- Poor limits of agreement were observed between Rint and Raw measurements (-1.52 to 2.74 kPa/l/s).
- After salbutamol, agreement remained poor (-0.28 to 1.44 kPa/l/s).
Conclusions:
- The interrupter technique (Rint) demonstrates insufficient agreement with plethysmography (Raw) in sedated, prematurely born infants.
- Rint measurements are not a reliable substitute for plethysmographic measurements in this specific pediatric population.
Background:
Airways obstruction in premature infants is often assessed by plethysmography, which requires sedation. The interrupter (Rint) technique does not require sedation, but has rarely been examined in children under 2 years of age.
Objective:
To compare Rint results with plethysmographic measurements of airway resistance (Raw) in prematurely born, young children.
Design:
Prospective study.
Setting:
Infant and Paediatric Lung Function Laboratories.
Patients:
Thirty children with a median gestational age of 25-29 weeks and median postnatal age of 13 months.
Interventions And Main Outcome Measures:
The infants were sedated, airway resistance was measured by total body plethysmography (Raw), and Rint measurements were made using a MicroRint device. Further Raw and Rint measurements were made after salbutamol administration if the children remained asleep.
Results:
Baseline measurements of Raw and Rint were obtained from 30 and 26 respectively of the children. Mean baseline Rint values were higher than mean baseline Raw results (3.45 v 2.84 kPa/l/s, p = 0.006). Limits of agreement for the mean difference between Rint and Raw were -1.52 to 2.74 kPa/l/s. Ten infants received salbutamol, after which the mean Rint result was 3.6 kPa/l/s and mean Raw was 3.1 kPa/l/s (limits of agreement -0.28 to 1.44 kPa/l/s).
Conclusion:
The poor agreement between Rint and Raw results suggests that Rint measurements cannot substitute for plethysmographic measurements in sedated prematurely born infants.
