ObjectiveTo examine the incidence and predictors of clinician discomfort with life support plans for ICU patients.Design and settingProspective cohort in 13 medical-surgical ICUs in four countries.Patients657 mechanically ventilated adults expected to stay in ICU at least 72 h.Measurements and resultsDaily we documented the life support plan for mechanical ventilation, inotropes and dialysis, and clinician comfort with these plans. If uncomfortable, clinicians stated whether the plan was too technologically intense (the provision of too many life support modalities or the provision of any modality for too long) or not intense enough, and why. At least one clinician was uncomfortable at least once for 283 (43.1%) patients, primarily because plans were too technologically intense rather than not intense enough (93.9% vs. 6.1%). Predictors of discomfort because plans were too intense were: patient age, medical admission, APACHE II score, poor prior functional status, organ dysfunction, dialysis in ICU, plan to withhold dialysis, plan to withhold mechanical ventilation, first week in the ICU, clinician, and city.ConclusionsClinician discomfort with life support perceived as too technologically intense is common, experienced mostly by nurses, variable across centers, and is more likely for older, severely ill medical patients, those with acute renal failure, and patients lacking plans to forgo reintubation and ventilation. Acknowledging the sources of discomfort could improve communication and decision making