On completion of the fluid challenge, ICU physicians were then called to review the patient immediately. A change of 10% or more in PP1-2, PP2-3, SV1-2, or SV2-3 was taken as a positive response to fluid challenge and triggered successive 500-mL crystalloid boluses until the PP or SV change was less than 10% or until the hypotension resolved (6). The results of these fluid boluses were again promptly recorded in the flowsheet. A 10% threshold was maintained regardless of cardiac rhythm to simplify the protocol and ease implementation, although this would likely lead to decreased specificity for volume response in patients with atrial fibrillation (22). Negative responses to fluid challenge or fluid boluses triggered a consideration for vasopressor use. The protocol could be repeated for persistent or recurrent shock. Data collection K.C.S., S.C.L., and S.M.T. retrospectively extracted data from medical records. Because all PBFM steps were recorded in the ICU computer, adherence could be accurately determined. Diagnosis was taken as the main diagnosis recorded in the ICU admission notes. The predominant cause of shock was derived from documented clinical judgment at the point of ICU admission. Glasgow Coma Scale scores were taken as the worst score before any sedation or intubation. Antibiotic therapy was considered discordant if blood or urine cultures were resistant to all of the empiric choices.