Balanced Solutions and Plasma Electrolytes (BASE)

The administration of intravenous fluids is ubiquitous in the care of the critically ill. Commonly available isotonic crystalloid solutions contain a broad spectrum electrolyte compositions including a range chloride concentrations. Recent prospective, randomized trials have shown improved patient outcomes with the use of balanced crystalloids compared to saline. There have not been large randomized studies comparing acetate buffered balanced crystalloids to non-acetate buffered balanced crystalloids in the critically ill. BASE will be a pilot study for a large, cluster-randomized, multiple-crossover trial enrolling critically ill patients from the Medical ICU at Vanderbilt University from June 2018 until January 2019. The primary endpoint will be plasma bicarbonate concentration between Intensive Care Unit admission and hospital discharge.

BASE is a pilot, cluster-randomized, multiple-crossover trial of lactated Ringer's versus Normosol-R pH 7.4 with regard to plasma bicarbonate concentration between intensive care unit admission and hospital discharge among all patients admitted to the medical intensive care unit. Between June 2018 and January 2019, all patients admitted to the medical intensive care unit at Vanderbilt University Medical Center who are 18 years or older will be enrolled. The study will occur in one-month blocks. The medical intensive care unit (MICU) will be randomized to an initial fluid group (lactated Ringer's or Normosol). The assigned fluid will be used exclusively for all patients receiving isotonic crystalloid for the duration of the month-long block (except in the presence of pre-specified contraindications). The assigned study fluid will switch at the end of each month-long block such that half of hte months are assigned to lactated Ringer's and half of the months are assigned to Normosol-R pH 7.4. It is anticipated that around 2,000 patients will be enrolled from the medical ICU during the study period. The primary outcome analysis will be an intention-to-treat comparison of the primary outcome of bicarbonate concentration (mmol/L) between enrollment and 7 days after enrollment between the lactated Ringer's and Normosol-R groups using generalized estimating equations with a random effect for study period and accounting for repeated measures.

Patients in a MICU block randomized to lactated Ringer's will receive lactated Ringer's whenever isotonic intravenous fluid administration is ordered by the treating provider.

Patients in a MICU block randomized to Normosol will receive Normosol-R pH 7.4 whenever isotonic intravenous fluid administration is ordered by the treating provider.

The primary outcome is a repeated measures variable of plasma bicarbonate concentration (mmol/L) between ICU admission and 7 days.

Plasma values for Sodium, Potassium, Chloride, Bicarbonate, Blood Urea Nitrogen, Creatinine, Calcium, and Lactate

This composite outcome will be considered present if at least one of the following occur: (1) A patient dies prior to the earlier of hospital discharge or day 30; (2) A patient receives new renal replacement therapy between enrollment and day 30, or (3) A patient has persistent renal dysfunction at the earlier of hospital discharge or day 30 (persistent renal dysfunction is defined as ≥ 200% of creatinine from baseline)

The initiation of any renal replacement therapy between enrollment and 30 days censored at hospital discharge in a patient not known to have previously received renal replacement therapy.

A patient will meet this outcome if they meet Kidney Disease Improving Global Outcomes (KDIGO) creatinine criteria for stage II acute kidney injury or higher

Intensive care unit-free days to day 28 (ICU-free days) will be defined as the number of days from the time of the patient's physical transfer out of the ICU until day 28 after enrollment. Patients who die prior to day 28 after enrollment received a value of 0 for ICU-free days. Patients who never transfer out of the ICU prior to day 28 after enrollment will receive a value of 0 for ICU-free days. Patients who transferred out of the ICU, return to the ICU, and are not subsequently transferred out of the ICU again before day 28 after enrollment will receive a value of 0 for ICU-free days. For patients who transfer out of the ICU, are readmitted to the ICU, and subsequently transfer out of the ICU again prior to day 28 after enrollment, ICU-free days will be awarded based on the time of the final transfer out of the ICU prior to day 28 after enrollment.

Vasopressor-free days to day 28 will be defined as the number of days from the time of vasopressor cessation until day 28 after enrollment. Patients who die prior to day 28 after enrollment will receive a value of 0 for vasopressor-free days. Patients who never cease to receive vasopressors prior to day 28 after enrollment receive a value of 0 for vasopressor-free days. Patients who achieve vasopressor cessation, return to receiving vasopressors, and do not again achieve vasopressor cessation before day 28 after enrollment receive a value of 0 for vasopressor-free days. For patients who achieve vasopressor cessation, return to receiving vasopressors, and subsequently achieve cessation of vasopressors again prior to day 28 after enrollment, vasopressor-free days will be awarded based on the time of the final cessation of vasopressors prior to day 28 after enrollment. Survivors who never receive vasopressors received 28 vasopressor-free days.

Renal replacement therapy-free days to day 28 (RRT- free days) will be defined as the number of days from the time of the final RRT treatment until day 28 after enrollment. Patients who die prior to day 28 after enrollment receive a value of 0 for RRT-free days. Patients who continue to receive RRT through day 28 after enrollment receive a value of 0 for RRT-free days. Patients who achieve RRT cessation, return to receiving RRT, and do not again achieve RRT cessation before day 28 after enrollment receive a value of 0 for RRT-free days. For patients who achieve RRT cessation, return to receiving RRT, and subsequently achieve cessation of RRT again prior to day 28 after enrollment, RRT-free days will be awarded based on the time of the final RRT treatment prior to day 28 after enrollment. Survivors who never receive RRT will be awarded 28 RRT-free days.

Ventilator-free days to day 28 (VFDs) will be defined as the number of days from the time of initiating unassisted breathing (breathing without support of the mechanical ventilator) until day 28 after enrollment. Patients who die prior to day 28 after enrollment will receive a value of 0 for VFDs. Patients who never achieve unassisted breathing prior to day 28 after enrollment will receive a value of 0 for VFDs. Patients who achieve unassisted breathing, returned to assisted breathing, and do not again achieve unassisted breathing before day 28 after enrollment will receive a value of 0 for VFDs. For patients who achieve unassisted breathing, return to assisted breathing, and subsequently achieve unassisted breathing again prior to day 28 after enrollment, VFDs will be awarded based on the time of the final initiation of unassisted breathing prior to day 28 after enrollment. Survivors who never experience assisted breathing will receive 28 VFDs.

Inclusion Criteria: Patients admitted to the Medical ICU during the study period (Enrolled patients who are discharged from the hospital are eligible again if they are readmitted to the Medical ICU during the study period) Exclusion Criteria: Age < 18 years old Prisoners

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