The Hospital of the University of Pennsylvania's Medical ICU (MICU) is implementing a model of 24-hour intensivist staffing in September 2011. Funds and resources are not available to cover the entire year, only certain weeks will be covered. The investigators propose a randomized clinical trial to study the comparative effectiveness of nocturnal intensivist staffing in the HUP MICU on patient outcomes. The investigators will be collecting and analyzing patient data of all patients admitted to the MICU from September 12, 2011, to September 11, 2012.

Available evidence suggests that intensivist management of critically ill patients improves patient outcome, suggesting that greater intensivist coverage might be better still. However, the effects of 24-hour intensivist coverage in ICUs are unknown. In FY11, leadership of the Hospital of the University of Pennsylvania (HUP) decided to roll-out a program for partial night-coverage of the Medical Intensive Care Unit (MICU). In light of this natural experiment, the investigators propose to study the comparative effectiveness of nocturnal intensivist staffing in the HUP Medical Intensive Care Unit. To do so, the investigators propose a randomized clinical trial comparing the presence of a nocturnal intensivist (in-hospital call) to a traditional model of nocturnal coverage with an intensivist available by phone (home call) in the HUP MICU, with respect to patient-centered outcomes and resource utilization. The investigators will randomly assign seven consecutive days (Monday through Sunday) at a time to in-hospital or home call, in two-week blocks. The investigators will conduct primary analyses of all patients admitted during night hours and secondary analyses of various subgroups of patients admitted during night hours as well as all patients admitted during any time of day during the study period from September, 2011, to June, 2011.

A sub-study designed to measure sleep and work duration, sleepiness, and attention in Daytime Intensivists (faculty and fellows) during their medical ICU rotation will be conducted. The variables measured will be compared between periods with and without in-house nocturnal intensivist staffing. All fellows and faculty who rotate through the medical ICU during this study period, Jan 2012 to Dec 2012 will be approached for possible recruitment.

Inclusion Criteria:

• Patients, 18 years and older, who are admitted to the HUP MICU during the 12-month study period will be included in the study.

Exclusion Criteria:

• No patients who meet these inclusion criteria will be excluded from this study.
• For patients admitted more than once to the MICU during the same hospitalization, we will include only their first admission to the MICU for all analyses.
• Subjects under 18 are very rarely seen at the HUP MICU because they are generally treated at the Children's Hospital of Philadelphia.
• In the rare event that a subject under the age of 18 receives care in the MICU his or her data will be excluded from this study.

For the Intensivist Sleep and Work sub-study looking at sleep, work hours, and attention of Daytime Intensivists during their MICU rotations:

• All University of Pennsylvania faculty members and fellows from the Division of Pulmonary, Allergy and Critical Care will be eligible for inclusion in the study if they rotate through the MICU during the study period (January, 2012 through December, 2012).

Exclusion Criteria:

• There are no exclusion criteria for this sub-study.

824 patients were randomized to the intervention group, 4 of which have been excluded from analyses to due incomplete data (n=820), 785 were randomized to the control group, 7 of which have been excluded from analyses due to incomplete data (n=778).