Critical Care Flashcards
What is compliance?
Change in volume divided by change in pressure
What is CPP (cerebral perfusion pressure)? Normal values?
MAP - ICP
>70 mm Hg
What is the substrate for lactate?
Pyruvate
Anaerobic pathway: pyruvate –> lactate by lactate dehydrogenase
Fate of lactate
Converted into glucose in the liver (or kidney) via Cori cycle
What is base deficit?
Indirect measurement of acidosis on ABG
What is weakness of base deficit as an end point of resuscitation?
Nonspecific.
Resuscitation with normal saline causes hyperchloremic acidosis.
What is currently the best end point of resuscitation?
Lactate
Normal I:E ratio?
1:2
What is RSBI?
RR/TV
>105 means likely to fail extubation
Treatment of auto-PEEP?
Decrease RR
Decrease TV
Increase expiratory time
Causes of hypoxia?
- Decreased inspired oxygen
- V/Q mismatch
- Shunt
- Decrease in barometric pressure (increased altitude)
- Diffusion (pulmonary edema or ARDS)
- Hypoventilation (airway obstruction)
Three determinants of oxygen delivery?
- CO
- Hgb
- O2 saturation of Hgb (SaO2)
Why does giving too much blood decrease oxygen delivery?
Increases viscosity of blood
What is the best marker of ventilation?
PaCO2 (on ABG)
What 2 barriers constitute the alveolar-capillary barrier?
- Microvascular endothelium
2. Alveolar epithelium
What is the pathogenesis of the early acute phase of ARDS?
Breakdown of the alveolar-capillary barrier and accumulation of transudate fluid (protein filled) in the alveolar air sac
Diagnostic definition of ARDS?
- Timing - less than 1 week after insult
- CXR - bilateral infiltrates
- Noncardiogenic edema
- P/F ratio < 300
Mild, moderate, severe ARDS p/f?
200-300 = mild 100-200 = moderate <100 = severe
Acetazolamide MOA (carbonic anhydrase inhibitor)?
Diuretic
Removes bicarbonate in the urine
Use in metabolic alkalosis
Milrinone MOA?
PDE III inhibitor
decreases breakdown of cAMP => increases intracellular levels of cAMP and calcium
positive inotrope
decreases afterload (SVR)
no net increase in myocardial oxygen consumption