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Respiratory rate: measurement of variability over time and accuracy at different counting periods
E A Simoes1, R Roark, S Berman
1University of Colorado, Health Sciences Center, Department of Pediatrics, Denver 80262.
Insights
Accurate respiratory rate monitoring in children under five is crucial. One-minute counts, whether continuous or in two 30-second intervals, offer better precision than 30-second counts, especially when children are asleep.
Area of Science:
- Pediatrics
- Respiratory Medicine
- Medical Instrumentation
Background:
- Accurate respiratory rate monitoring is vital for diagnosing and managing pediatric respiratory conditions.
- Variability in respiratory rate measurements can impact clinical assessment.
- Pneumography offers a potential objective method for respiratory rate assessment.
Purpose of the Study:
- To compare the accuracy and variability of respiratory rate measurements obtained by observer and pneumogram in young children.
- To evaluate the impact of counting duration (30 seconds vs. 60 seconds) and patient state (sleeping, awake, agitated) on measurement accuracy.
- To assess measurement reliability in children with different respiratory infection statuses.
Main Methods:
- Simultaneous monitoring of respiratory rates in 97 children (<5 years) using observer counts and pneumography over one hour.
- Respiratory rates were counted over 30-second and 60-second intervals.
- Analysis of the difference and variability between observer and pneumogram counts in relation to patient state and infection status.
Main Results:
- Mean differences between observer and pneumogram counts were 1.79 (60s), 1.42 (30s+30s), and 1.72 (30s doubled).
- Measurement variability was lower when children were sleeping and higher when agitated.
- Lower variability was observed in children with lower respiratory tract infections compared to upper respiratory tract infections or controls.
Conclusions:
- One-minute respiratory rate counting (continuous or split) is more accurate than 30-second counts in young children, particularly when asleep.
- Patient state significantly influences measurement variability, with sleep reducing and agitation increasing it.
- Children with lower respiratory tract infections exhibit more stable respiratory rates during monitoring.
Abstract:
The respiratory rates/minute of 97 children were monitored every 10-15 minutes over one hour, by an observer and by pneumogram, at which times two 30 second and one 60 second counts were obtained. The children were under 5 years of age with lower respiratory tract infections (n = 20), upper respiratory tract infections (n = 34), or controls without acute respiratory infection (n = 43). The difference between respiratory rate count determined simultaneously by observation and pneumogram in relation to their mean count was analysed for the 60 second counting period, 30 plus 30 second period, and the 30 second period doubled. The mean difference for the 60 second period was 1.79, for the 30 plus 30 second period 1.42, and for the 30 second period doubled 1.72. The variability between respiratory rate counts determined by observation and pneumogram was significantly lower in counts obtained when the subject was sleeping and higher when agitated compared with obtaining a count when the subject was awake and calm or feeding. The variability was also significantly lower in subjects with lower respiratory tract infections compared with those with upper respiratory tract infections and control subjects without respiratory symptoms. In the same patient, over the one hour, 50% of the 60 second counts varied by up to 14 breaths/minute and 75% by up to 21 breaths/minute. The least variability was seen in children with a lower respiratory tract infection, who tended to maintain their rapid breathing in contrast to those with an upper respiratory tract infection and controls without respiratory symptoms. About 10% of initial 30 second counts, 12% of 60 second, and 16% of initial and repeat 30 second attempts to obtain accurate counts failed. Failures occurred more frequently in children <2 months of age and those agitated. The data from this study suggest that one minute's counting either at a stretch or in two blocks of 30 second intervals is better than counting the respiratory rate for 30 seconds, when the child is either awake and calm or when asleep.