Serial single breath count is a reliable tool for monitoring respiratory functions in Guillain-Barré Syndrome.

In this study, we correlate single breath count (SBC) with arterial blood gas (ABG) parameters to derive a cutoff point for intubation and mechanical ventilation (MV) in Guillain-Barré Syndrome (GBS). Ninety-four GBS patients underwent serial SBC at 2 Hz using an audio program. ABG was done at admission, and repeated if SBC declined. The patients were intubated based on "the modified intubation criteria" as follows (a + b or c): (a) hypoxia (PaO2  < 60 mm of Hg on ventimask); (b) hypercarbia (PaCO2  > 50 mm of Hg); (c) acidosis (pH < 7.3). The primary outcome was the absolute SBC at which patients had ABG alteration needing intubation. All the patients maintained a desired ABG without respiratory distress till SBC 7. At SBC 5, need for MV could be predicted with a sensitivity of 90.6% and specificity of 95.2%. Admission SBC cut-off of 13 and relative delta SBC at 24 h cut-off of > 20% had a negative predictive value of 88.5% (95% CI 77.0%-96.0%) and 80.8% (95% CI 60.7%-93.4%) respectively for ruling out need of MV. SBC is a useful non-invasive measure for monitoring respiratory function and guiding ABG analysis. Till SBC 7, repeated ABG may be avoided in GBS.