Rapid shallow breathing (frequency-tidal volume ratio) did not predict extubation outcome

Chest. 1994 Feb;105(2):540-3. doi: 10.1378/chest.105.2.540.


This was a prospective study of 52 patients that were extubated in our medical intensive care unit. Rapid shallow breathing, represented by a ratio of frequency to tidal volume (f/VT) of more than 105, was evaluated either on continuous positive airway pressure or pressure support prior to extubation as a marker of extubation outcome. Twelve out of 13 patients (92 percent) with rapid shallow breathing (f/VT ratio > 105) were successfully extubated. Out of 9 extubation failures only 1 patient had a f/VT ratio more than 105 (11 percent). A measured f/VT ratio of less than 105 had a sensitivity and specificity of 72 and 11 percent, respectively, for extubation success. Patients who had unsuccessful outcomes were ventilated for a significantly more prolonged period (9.6 +/- 6.8 d vs 4.6 +/- 3.9 d, unpaired t test, p = 0.004). We conclude that the presence of rapid shallow breathing during a weaning trial with the patient on partial ventilatory support does not necessarily preclude successful extubation.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Female
  • Forecasting
  • Humans
  • Intubation, Intratracheal*
  • Lung Diseases / physiopathology
  • Lung Diseases / therapy
  • Male
  • Middle Aged
  • Positive-Pressure Respiration / instrumentation
  • Prospective Studies
  • Respiration / physiology*
  • Respiration, Artificial / instrumentation
  • Sensitivity and Specificity
  • Survival Rate
  • Tidal Volume / physiology*
  • Treatment Failure
  • Treatment Outcome
  • Ventilator Weaning*