Figure 1.

Heat map depiction of the univariable risk of ICU hypoglycemia as a function of 61 measured physiologic and biochemical variables. Each tile plots the value of the variable on the x-axis against the relative risk of ICU hypoglycemia on the right y-axis. Variables on the left y-axis represent model outputs, with those in red text indicating laboratory values, those in blue text indicating hemodynamic monitoring variables, and those in green text indicating electrophysiology variables. The relative risk color bar ranges from 0.50 to 2.0. A red color saturation indicates higher relative risk of hypoglycemia; a blue color saturation indicates a lower relative risk. <RRI> = mean R-R interval, AF = probability of atrial fibrillation, AGAP = anion gap, Alb = albumin, ALP = alkaline phosphatize, ALT = alanine aminotransferase, AST = aspartate aminotransferase, BE = base excess from arterial blood gas, Bili = bilirubin, BUN = blood urea nitrogen, BUN/Cr = blood urea nitrogen/creatinine, Ca = calcium, Cl = chloride, CO₂ = carbon dioxide, COSEn = coefficient of sample entropy of R-R interval, Cr = creatinine, DBP (cuff) = diastolic blood pressure by cuff measurement, DBP = invasive diastolic blood pressure (mm Hg), DFA = detrended fluctuation analysis applied to R-R intervals, EDR = electrocardiogram-derived respiratory rate (breaths/min), Gluc = glucose, Hco₃ = bicarbonate, Hct = hematocrit, HR = heart rate measured by cardiac telemetry (beats/min), HRV = sd of heart rate by cardiac telemetry (beats/min), HRxEDR = cross-correlation coefficient of heart rate and electrocardiogram-derived respiratory rate, HRxRR = cross-correlation coefficient of heart rate measured by cardiac telemetry and respiratory rate measured by chest impedance, HRxSO2 = the cross-correlation coefficient of heart rate and oxygen saturation, K = potassium, Lact = lactate, LDd = local dynamics density of heart rate, MAP = mean arterial pressure by cuff measurement, MBP = invasive mean blood pressure (mm Hg), Mg = magnesium, Na = sodium, Neut % = neutrophil percentage (%), O₂ = oxygen saturation from arterial blood gas, O2V = the sd of oxygen saturation by pulse oximetry, pH = pH from arterial blood gas, Plt = platelet count, Po₂ = Po₂ from arterial blood gas, PO₄ = phosphorous, PT/INR = prothrombrin time/international normalized ratio, PTT = partial thromboplastin time, Pulse = heart rate measured by pulse oximetry (beats/min), Resp = respiratory rate measured by pulse oximetry, RR = respiratory rate measured by chest impedance, RRV = sd of respiratory rate by chest impedance (breaths/min), RRxSO2 = cross-correlation coefficient of respiratory rate measured by chest impedance and oxygen saturation measured by pulse oximetry, SBP (cuff) = systolic blood pressure by cuff measurement, SBP = invasive systolic blood pressure (mm Hg), SO₂ = oxygen saturation measured by pulse oximetry (%), Spo₂ = clinician-documented oxygen saturation (%), sRRI = the sd of R-R intervals, Temp = temperature (°C), TP = total protein, Trop I = troponin I