Critical Care.pdf

Critical Care: Physiology and Medicine Common medications used in the ICU. - When they are mechanically ventilated. - They usually get PPI. - Delirium – 섬망 PKPD in the critically ill - Drug concentration in systemic circulation à may change due to changes in kidney function...

Critical Care: Physiology and Medicine Common medications used in the ICU. - When they are mechanically ventilated. - They usually get PPI. - Delirium – 섬망 PKPD in the critically ill - Drug concentration in systemic circulation à may change due to changes in kidney function or liver metabolism. à Doses can change a lot. - Can change volume of distribution. PKPD alterations in the critically ill. - Mechanically ventilated à air is pushed into the lungs à increases the pressure within the chest à changes cardiac output à aBects pressure on the heart à changes in blood flow to various organs like kidneys and liver à changes in elimination. - Renal replacement therapy à works like kidney, but not same as kidney. The drug dosing is dependent on RRT. - Ecmo à Replace cardiac output. - When they are critically ill à usually comorbidities. Absorption - PPI can change the dissolution and absorption of the drug. - Decreases perfusion à decreases absorption and aBect gastric motility. Distribution Which drugs are expected to have a lower Vd? - Hydrophilic drug à stay within central compartment. - Lipophilic cross membrane. - Drugs going to be aBected à hydrophilic drug. Protein binding. - Low albumin à aBects protein binding. à e.g. warfarin. - Highly protein binding drugs will be highly aBected. In high protein bound drugs with high renal clearance, what would happen to drug concentrations in the plasma if albumin decreased? - Concentration will be decreased. - Will not have suBicient therapeutic eBect. Metabolism - Enzymes in liver may stop functioning à decrease in blood flow à may decrease metabolism. - If albumin is low, fraction unbound drug increase à liver clears more. - Drugs that have low extraction ration à more dependent on enzymatic function. - High extraction ratio à dependent on blood flow. Elimination - Decrease in clearance. - Some people will have hyperdynamic state à usually happens in young people. à clearance increase. Renal Replacement Therapy (RRT) - Dialysis (투석) - Continuous dialysis. - You can’t use serum creatinine to calculate CrCl for drug dosing. - It’s just clearance of the machine. Extracorporeal Membrane Oxygenation (ECMO) - Substituent of lung and heart. Extracorporeal Membrane Oxygenation (ECMO) - Morphine is preferred for analgesic. - Nobody knows the net change. à need to monitor. Drug information sources. Case study - 4.5g every 8 hours. - Increase the frequency à because drugs are getting cleared. - Highly protein bound drug, vd increased, Cl increased. - 1 g IV 12h.