Case 5: Fluid Volume Calculations
Ins and Outs

TID Maintenance = [(30 x 4.8) + 70] = 214 ml/day/3 = 71 mls

    Maintenance = Sensible Losses (2/3) + Insensible (1/3)
or
Ins and Outs Maintenance = Sensible Losses (Urine Volume over the past 8 hours) PLUS Insensible Losses [(Maintenance X 0.33)/3]

Total fluid requirement for the next 8 hours =  1/3 daily maintenance over 8 hours PLUS urine output from the last 8 hours  
Urine output over the past 8 hours = 315 mls

71/3 ml + 315 ml = 24 + 315 = 339 ml (approximately 42 ml/hour)