Storyboard

Life support artificially replaces physiological functions that the body cannot maintain autonomously. Mechanical ventilation (MV) replaces the function of the diaphragm and respiratory muscles: it delivers the tidal volume (VT = 6 mL/kg of ideal weight for protective ventilation) exceeding the elastance (E_RS = 1/C_RS) and the resistance of the respiratory system (R_RS). The equation of motion of the respiratory system allows calculating the plateau pressure (P_plat, marker of alveolar overdistension) and the driving pressure (P = P_plat - PEEP, target < 15 cmHO).

Dialysis (hemodialysis or continuous hemofiltration in ICU) replaces the excretory function of the kidney. Kt/V is the standard dialysis dose rate: K = dialyzer urea clearance (mL/min), t = duration (min), V = urea volume of distribution. The Daugirdas equation corrects for urea production during the session and ultrafiltration. Kt/V 1.2 per session (3×/week) or 1.2/week for HFVVC is the minimum objective.

ECMO (extracorporeal membrane oxygenation) simultaneously replaces the heart (VA ECMO) or the lung (VV ECMO) or both. Oxygenation efficiency follows Fick's principle: VO_ECMO = Q_ECMO × (CaO_out - CvO_in) × 10. For severe ARDS with residual CO of 4 L/min, an ECMO flow of 3 L/min (75% of CO) can support 75% of the O consumption. The balance between ECMO support and residual native function determines the weaning strategy.

Total parenteral nutrition (TPN) delivers macronutrients (glucose, lipids, amino acids) and micronutrients directly to the central vein. Nitrogen balance (BN = N_intake - N_excreted) quantifies the catabolic state: BN < -5 g/day in critically ill patients indicates severe muscle protein catabolism. The goal is BN 0 (eunitrogenemia) or slightly positive (+2 to +4 g N/day in recovery), requiring 1.22 g protein/kg/day.

Ventilator weaning is the process of progressively transferring the work of breathing from the ventilator to the patient. The RSBI = FR/VT is the most robust validated predictor: RSBI < 105 rpm/L predicts success with a sensitivity of 97% and specificity of 64%. The pressure support (PSV) is gradually reduced, while the patient's work of breathing (WOB_pac) is monitored. Weaning failure (criterion: RR > 35, SpO < 90%, or agitation) requires restarting full MV.

>Model

ID:('ky', 59)

Description

ID:(0, 59)