LAUSR

RATIONALE Guidelines for vasopressor titration suggest a universal target-mean arterial pressure (MAP) >65 mmHg. The implications for patients with pre-morbid low/high blood pressure are unknown. OBJECTIVE To investigate the relationship between pre-morbid blood pressure and vasopressor duration for patients with shock. METHODS We performed a retrospective cohort study of adults admitted with shock to Calgary intensive care units (June, 2012-December, 2018). The primary exposure was pre-morbid blood pressure: low (systolic<100); normal (systolic 100-139 and diastolic<90); high (systolic ≥140 or diastolic ≥90). The primary outcome was vasopressor duration; secondary outcomes included ICU/hospital length of stay and ICU/hospital mortality. We examined associations of pre-morbid blood pressure with vasopressor duration and length of stay using multivariable competing risks models and mortality using multivariable mixed effects logistic regression. MEASUREMENTS AND MAIN RESULTS Of 3,542 admissions with shock, 177 (5.0%) had pre-morbid low, 2,887 (81.5%) normal, and 478 (13.5%) high blood pressure. Pre-morbid low admissions had lower MAPs (vs normal or high pre-morbid admissions) over the duration of vasopressor use (p=0.003) and were maintained nearest pre-morbid MAPs while receiving vasopressors (p<0.001). After adjustment, pre-morbid low admissions had longer vasopressor use (median: 1.35 days versus 1.04 days for normal; hazard ratio for discontinuation vs normal: 0.78 (0.73,0.85), p<0.001) and pre-morbid high admissions had shorter use (median: 0.84 days; HR 1.22 (1.12,1.33), p<0.001 ). Pre-morbid low admissions had longer adjusted length of stay and higher adjusted mortality than pre-morbid normal admissions. CONCLUSIONS Pre-morbid blood pressure was inversely associated with vasopressor duration.