Background

We investigated the utility of Tympanic Membrane Displacement (TMD) Analyser in monitoring children with acute coma

Methods

Between November 2007 and September 2009, we made serial TMD and clinical observations on children with acute coma (Blantyre coma score ≤ 2) at the paediatric high dependency unit of our hospital. We examined middle ear function using tympanometry and measured cardiac pulse (CPA) and respiratory pulse pressure amplitudes (RPA) using the TMD analyser. We applied multivariable logistic regression to examine the association between TMD measurements and, clinical features of raised ICP, and death.

Results

We recruited 75 children [median age 3.3 (Inter-quartile range (IQR) 2.0, 4.3) years].Children with clinical features of raised ICP had higher maximum CPA [median 248 (IQR 198,350) nl] and RPA [median 487 (IQR 295,836) nl] measurements in the semi-recumbent position compared to those without; [CPA median 158 (IQR 123,288) nl; P=0.02, and RPA median 292 (IQR 183,365) nl P<0.01].  A unit rise in log of initial semi-recumbent CPA and RPA, and recumbent CPA measurements, were associated with increased risk of death; Odds ratio (OR) 4.0 (95%C.I. 1.3, 12.3; P=0.01), OR 3.7(95%C.I. 1.0, 14.1; P=0.05) and OR 3.5(95%C.I. 1.3, 9.3; P=0.01) respectively. Abnormal tympanometry was associated with greater risk of death compared to normal tympanometry (OR 16.3 95% C.I. 1.7-158.5; P<0.01).

Conclusion

TMD pulse pressure measurements predict death and may be useful in detecting and monitoring raised ICP in childhood coma. Abnormal tympanometry appears to predict death and may be related to altered ICP dynamics.