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Critical Illness

CI: Best Method to Estimate RMR (2010)

Predictive Equation Formulas Used in Critically Ill Adults

Brandi Equation

HBE(0.96) + HR(7) + VE(48) – 702

VE = expired minute ventilation

Faisy Equation

W (8)+H (14)+VE (32)+T (94)-4,834
 

Equation uses weight (W) in kilograms (kg) and height (H) in centimeters (cm). VE is expired minute ventilation and T is body temperature in degrees centigrade.
 

Fick Equation
 

RMR=CO x Hb(SaO2-SvO2)95.18
 

Equation uses cardiac output (CO) in liters per minute (L/min), hemoglobin concentration (Hb) in mg/L, oxygen saturation of arterial blood (SaO2) and oxygen saturation of mixed venous blood (SvO2).
 

Harris-Benedict Equations (HBE)  
 

Men: RMR = 66.47 + 13.75 (W) + 5 (H) - 6.76 (A)
Women:  RMR = 655.1 + 9.56 (W) + 1.7 (H) - 4.7 (A)
 

Equation uses weight (W) in kilograms (kg), height (H) in centimeters (cm), and age (A) in years.
 

Ireton-Jones, 1992 Equations

Spontaneously breathing IJEE (s) = 629 - 11 (A) + 25 (W) - 609 (O)

Ventilator dependent IJEE (v) = 1925 - 10 (A) + 5 (W) + 281 (S) + 292 (T) + 851 (B) 
 

Equations use age (A) in years, body weight (W) in kilograms (kg), sex (S, male = 1, female = 0), diagnosis of trauma (T, present = 1, absent = 0), diagnosis of burn (B, present = 1, absent = 0), obesity >30% above initial body weight from 1,959 Metropolitan Life Insurance tables or body mass index (BMI) more than 27kg/m2 (present = 1, absent = 0).

Ireton-Jones, 1997 Equations

Spontaneously breathing IJEE (s) = 629 - 11 (A) + 25 (W) - 609 (O)

Ventilator dependent IJEE (v) = 1784 - 11 (A) + 5 (W) + 244 (S) + 239 (T) + 804 (B) 

Equations use age (A) in years, body weight (W) in kilograms (kg), sex (S, male=1, female=0), diagnosis of trauma (T, present=1, absent=0), diagnosis of burn (B, present=1, absent=0), obesity more than 30% above initial body weight from 1959 Metropolitan Life Insurance tables or BMI higher than 27kg/m2 (present=1, absent=0).

Penn State Equations (PSU)

  • PSU(1998) - Invalidated in 2009

RMR = HBE(1.1) + VE (32) + Tmax (140) - 5340
[use adjusted body weight in HBE for patients with BMI>30kg/m2]
 

  • PSU(2003a) - Invalidated in 2007 and 2009

RMR = HBE(0.85) + VE (33) + Tmax (175) - 6433
           [use actual weight in all patients]

  • PSU(2003b) - Validated in 2009 and also referred to as Penn State Equation

RMR = Mifflin(0.96) + VE (31) + Tmax (167) - 6212

  • PSU(2010) - Validated in 2010 and also referred to as Modified Penn State Equation

RMR = Mifflin(0.71) +  VE (64) + Tmax(85) - 3085
 

Mifflin-St. Jeor Equation (MSJE)

Men: RMR = (9.99 X weight) + (6.25 X height) – (4.92 X age) + 5

Women: RMR = (9.99 X weight) + (6.25 X height) – (4.92 X age) – 161
 

Equations use weight in kilograms (kg), height in centimeters (cm).

Swinamer Equation

EE = 945 (BSA) - 6.4 (age) + 108 (T) + 24.2 (breaths per minute) + 81.7 (VT) - 4,349

Equation uses body surface area (BSA) in squared meters (m2), temperature (T) in degrees Celsius, and tidal volume (VT) in liters per minute (L per minute).