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Hospital volume and outcome following mechanical ventilation on the intensive care unit


The study was undertaken to determine the relationship between hospital volume and mortality in mechanically ventilated adult medical and surgical patients. The regionalisation of adult critical care services has been suggested by healthcare providers and health policy-makers as a means of achieving the ideal balance of providing high-quality care that is both cost-effective and accessible. Recent studies have had conflicting results.


The Birmingham and Black Country Critical Care Network database was retrospectively reviewed over a 10-year period from 1 April 1996 to 31 March 2006. The database included 50,686 patient episodes. After exclusion (incomplete data 9,700 episodes, unventilated patients 19,244 episodes, mechanical ventilation for less than 24 hours 3,814 episodes, interhospital transfers 795 episodes) the final cohort included 9,920 adult medical patients and 7,210 surgical patients. Hospitals were grouped into five volume categories to aid interpretation of the results (<100; 100–149; 150–199; 200–249; ≥250 ventilation episodes/year). The odds ratio and 95% confidence intervals for death on the ICU were calculated in relation to the hospital volume of ventilation.


For both medical and surgical patients there was no relationship between the hospital volume of ventilation and death on the ICU. The odds ratio remained insignificant even after adjustment for patient demographics, APACHE II score, length of ICU stay and urgency status. Medical patients' adjusted odds ratio was 0.735 (95% CI 0.604–0.894). Surgical patients' adjusted odds ratio was 0.771 (95% CI 0.559–1.064).


There is no relationship between hospital volume and ICU mortality in both medical and surgical patients following mechanical ventilation. The results of this study do not support the argument for regionalisation of adult critical care services in the United Kingdom.

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  • Mechanical Ventilation
  • Adjusted Odds Ratio
  • Medical Patient
  • Hospital Volume
  • Volume Category