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Oximetry-detected pulsus paradoxus predicts for severity in paediatric asthma
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  • Published on:
    Oximetry-detected pulsus paradoxus predicts for severity in paediatric asthma
    • Paul Seddon, Respiratory Paediatrician Royal Alexandra Children's Hospital, Brighton
    • Other Contributors:
      • David Wertheim, Professor, Computer Science

    We read with interest the paper by Krishnan et al.1 and agree that "pulsus paradoxus" (PP) of the oximetry plethysmogram (pleth) may be useful in assessing severity of acute asthma exacerbations in children. The visual assessment they propose is one of a number of approaches which have been used, with variable success in predicting clinical outcomes2,3,4.

    Rather than pulse amplitude variation associated with respiration, figure 2 in the paper1 shows predominately baseline undulation, at a rate of about 1/5 to 1/6 of pulse rate; no time base nor simultaneous respiratory waveform is included. Can the authors thus be sure that the variation is due to respiration, and if it is, could the baseline variations in fact be associated with respiratory-related changes in peripheral blood volume? As the visual pleth display is dependent on processing by the pulse oximeter, it would be helpful to know more about the oximeter used.

    We have monitored respiration using Respiratory Inductance Plethysmography (RIP) bands simultaneously with oximetry pleth in children with acute wheezing illness using a SOMNOscreen plus recorder (SOMNOmedics GmbH, Germany) with Nonin oximeter module (Nonin Medical Inc., USA). We developed software in MATLAB (The MathWorks Inc., USA) for quantifying pleth pulse amplitude to assess pulsus paradoxus analogous variation. Consistent with Krishnan et al., we found that chil...

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    Conflict of Interest:
    None declared.