Critical Care: Physiology and Medicine PDF
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This document provides an overview of common medications used in intensive care units (ICUs). It discusses factors affecting pharmacokinetics (PKPD) in critically ill patients and includes considerations for renal replacement therapy (RRT) and extracorporeal membrane oxygenation (ECMO). The document also notes common case studies relating to drug dosing in critical care.
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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.
