Dear Editor

The data presented by Breen et al[1] regarding the outcomes of patients with COPD are encouraging and lend support to the respiratory physician often faced with nihilistic attitudes towards ventilating these patients in acute respiratory failure. However, despite the proposition by the authors that certain patients with likely poor outcomes might have been excluded, the ICU stays for both groups (intubated and non-intubated) are strikingly short.

This suggests that the threshold for intubation as opposed to non- invasive ventilation (NIV) may have been lower before 1994 than in current practice. Although the authors explain the reason for the high levels of PaO2 on admission to the ICU, it could be that the severity of respiratory acidosis may have reflected excess oxygen therapy rather than the severity of the underlying mechanical respiratory failure, thus being more readily reversible and requiring a shorter period of ventilatory support. Although the decision to intubate is not solely based upon blood gases, with the increasing availability of NIV, it might be that a subgroup of these patients would now be managed using controlled oxygen therapy, respiratory stimulants and NIV[2].

As a result, I suspect that the physiological state of the patient that we offer to the ICU in our current practice may be worse than in this study with commensurate outcomes (longer stays and higher mortality). Despite this, many patients still do well and studies of this type need to continue to assess predictors of unfavourable end-points.

Luke Howard MA, DPhil, MRCP.
Department of Respiratory Medicine, Norfolk & Norwich University Hospital, Colney Lane, Norwich, NR4 7UY, UK

References
(1) Breen D, Churches T, Hawker F, Torzillo PJ. Acute respiratory failure secondary to chronic obstructive pulmonary disease treated in the intensive care unit: a long term follow up study. Thorax;57:29-33.
(2) Plant PK, Owen JL, Elliott MW. Early use of non-invasive ventilation for acute exacerbations of chronic obstructive pulmonary disease on general respiratory wards: a multicentre randomised controlled trial. Lancet;355:1931-1935.