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PP09 Pre-hospital diagnostic accuracy for hyperventilation syndrome
  1. Caitlin Wilson,
  2. Clare Harley,
  3. Stephanie Steels
  1. University of Leeds, North West Ambulance Service


Background Hyperventilation syndrome (HVS) encompasses a wide variety of symptoms and is diagnosed by excluding organic causes for patients’ symptoms. Literature suggests that HVS should be diagnosed and treated pre-hospitally to avoid costly attendances at Accident and Emergency departments. The study aim was to determine diagnostic accuracy for HVS of paramedics and emergency medical technicians (index test) in comparison to hospital doctors (reference standard).

Methods A retrospective cross-sectional audit of routine data utilising linked pre-hospital and in-hospital patient records of adult patients (age ≥18 years) transported via emergency ambulance to two Accident and Emergency departments in the United Kingdom from January 2012 – December 2013. Agreement between pre-hospital and in-hospital HVS diagnoses was calculated using percent agreement, Cohen’s kappa and prevalence-adjusted bias-adjusted kappa. Accuracy was measured using sensitivity, specificity, predictive values and likelihood ratios with 95% confidence intervals.

Results A total of 19 386 records were included in the analysis. Percent agreement between pre-hospital clinicians and hospital doctors was 98.73%, producing kappa of κ=0.57 and adjusted kappa of PABAK=0.97. Pre-hospital clinicians had a sensitivity 0.88 (0.82, 0.92) and specificity 0.99 (0.99, 0.99) for diagnosing HVS, with PPV 0.42 (0.37, 0.47), NPV 1.00 (1.00, 1.00), LR +75.2 (65.3, 86.5) and LR- 0.12 (0.08, 0.18). Subgroup analyses for sensitivity were statistically non-significant but for positive predictive values were statistically significant (p<0.001) for the number of pre-hospital diagnoses and patient age.

Conclusions Paramedics and emergency medical technicians were able to diagnose HVS pre-hospitally with almost perfect specificity and good sensitivity. Pre-hospital diagnostic accuracy was highest for patients less than 30 years of age and if HVS was the sole diagnosis documented. Following this study, a review of the local ambulance service policy excluding adult HVS patients from referrals to Primary Care Services is anticipated.

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