Pharmacology in ICU (Shih) Flashcards
Venous shunts
open and close depending on need
- organs
- muscles
- skin
- fat
hypovolemic shock
- Body compensates shuts down peripheral circulation
- venous shunt closes
- main arteries and vessels are closed
- inc blood pressure
- Selective organ perfusion
- sacrifices
- skeletal muscles
- intestines
- keep central perfusion
- brain
- heart
- lung
Distributive shock
Body loses ability to select what is important
- venous shunt opens everywhere
- hypoperfusion => hyperdynamic stage of sepsis
- volume of distribution is HUGE: pressure crashes
- Infection / sepsis
- Anaphylactic shock
- heat stroke
- pancreatitis
- inflammation
- cancer
Volume of distribution in ICU
- Hypovolemic shock: reduction in Vd (volume of distribution)
- Distributive shock: increase in Vd
Stab wounds you….
Concentrate your blood
Sepsis you ……
Dilate too much
volume of distribution, percent blood volume per body weight
20%
change in volume of distribution wil change…
Cmax (max concentration of drug)
Volume of distribution
- Hemoabd
- Post burn
- Aspiration pneumonia
- Abdominal exploritory
- Anesthetized patient, lar par
- CKD (UTI)
- Septic abdomen
- Collapse (post CPR)
- Hemoabdomen: lower
- Post burn: can be higher or lower
- loss of skin = loss of water = usually lower
- in sepsis = higher
- Aspiration pneumonia: high (sepsis)
- Abdominal exploritory: low (lose volume to evaporation)
- Anesthetized patient, lar par: High isofluorene simulates sepsis (vasodilator)
- CKD (UTI): low, dehydrated, cant concentrate urine
- Septic abdomen: high
- Collapse (post CPR): high, reperfusion injury because CPR doesn’t circulate as well as the heart
* serous inflammatory response syndrome
patient dose of drug
[(Standard dose) X Vd] / (normal Vd of patient)
Solubility of Rx in ICU
- Hypovolemic shock: …
- Distributive shock: …
- Lipossoluble Rx: …
- Hydrossoluble Rx: …
- Hypovolemic shock: reduction Vd
- Distribution shock: increase Vd
- Lipossoluble Rx: no change Cmax
- Hydrossoluble Rx: drop in Cmax
- Liposoluble drugs go to…..
- Hydrosoluble drugs go …
- Whole body
- Where blood goes
Low Vd =
concentratin of blood
Septic shock (change in Vd)
- Trying to perfuse the whole body
- huge Vd
- hydrosoluble drug
- Liposoluble: no change in Cmax
- Hydrosoluble: Drop of Cmax
- Septic shock = …..in Vd
- Hemorrhagic shock =…in Vd
- Septic shock = drop in Vd
- Hemorrhagic shock = inc in Vd
Liposoluble antibiotics
- Chloranfenicol
- TMS
Hydrosoluble antibiotics
- Beta Lactams
- Aminoglycosides
Amikacin
hydrosoluble:
am I going to inc cmax in this patient is it going to be too high?
*enrofloxacin has less side effects
Protein binding in ICU
affected
Loss
Redistribution
Lack of production
Conditions prone to low protein
- Hemoab:
- Burn:
- Post CPR inflamed dog:
- Septic abdomen:
- Aspiration pneumonia:
- Abdom explore:
- Anesthesia:
- CKD (UTI):
- Hemoab: low
- Burn: low
- Post CPR inflamed dog: low
- Septic abdomen: low
- Aspiration pneumonia: low
- Abdominal explore: low
- Anesthesia: normal
- CKD (UTI): low
Protein and the BBB
Drug bound to protein does not cross the BBB
When do we worry about low protein and drugs?
Drugs that have a low therapeutic index
- aminoglycosides
Low protein in blood allows:
Higher % free drug in plasma
Higher chance of side effects
More effected the blood
Drugs that require protein binding to work
Propofol
Digoxin
Dz states prone to low clearance
- Hemoabdomen:
- Burn:
- Septic abdomen:
- CKD (UTI)
- Anesthesia
- Abdominal explore:
- Aspiration pneumonia:
1. Hemoabdomen: yes
- Burn: yes
- Septic abdomen: yes
- CKD (UTI): yes
- Anesthesia: yes
- Abdominal explore (GDV): yes
- Aspiration pneumonia: yes
If a patient is prone to low clearance….
Reduce dose
or
Increase interval
