Critical Care Flashcards
What are three mechanisms of ventilator induced lung injury?
- volume
- pressure
- oxygen toxicity
What is the difference between peak and plateau airway pressure?
- peak reflects pressure in the larger airways
- plateau is obtained during an inspiratory pause, allowing pressures to equilibrate, and therefore reflects alveolar pressure
What is signaled by a large difference between peak and plateau airway pressures?
a large airway obstruction (e.g. foreign body, bronchospasm, etc.)
What is signaled by equally high peak and plateau airway pressures?
alveolar lung disease such as ARDS
What is continuous mandatory ventilation/assist control?
a mode of ventilation where RR and volume are set and every breath is fully supported
What is the primary disadvantage of pressure support ventilation?
it can result in hypoventilation
What is synchronous intermittent mandatory ventilation?
- a mode of ventilation for which RR and volume are set
- spontaneous breaths above the set rate are not fully supported
- mandatory breaths are synchronized
What are important factors and criteria to consider for extubation?
- tolerate a daily pressure support trial
- follows commands when off sedation
- FiO2 < 50, PEEP < 10
- RSBI < 100 (best predictor)
- NIF > 20
What is the best predictor of successful extubation?
an RSBI < 100
How is RSBI calculated?
as RR/TV
What is the utility of NIF in considering extubation?
< 20 is a good predictor of failure but > 20 doesn’t have much predictive value for success
What are the criteria for diagnosing ARDS?
- occurs within one week of insult
- has characteristic CXR findings
- rule out cardiogenic causes
- P/F < 300
What is considered low tidal volume ventilation?
4-6cc/kg
What are the major strategies for ventilation in ARDS patients?
- low TV ventilation (4-6cc/kg)
- permissive hypercapnia to pH 7.20
- airway pressure release ventilation
- prone positioning
- paralysis
- NO
What is APRV ventilation?
- airway pressure release ventilation
- set a P-high, P-low, T-high, and T-low for a long inhalation period and short exhalation
What are the new definitions for sepsis and septic shock?
- sepsis = SOFA of 2 or more on presentation or an increase of 2 or more after
- septic shock = pressor requirement and lactate of 2 or more despite resuscitation
What is the utility of procalcitonin?
- high sensitivity for sepsis but low specificity
- when it normalizes, it is an indicator to stop antibiotics
What is the utility of 1,3 beta-d-glucan?
if elevated, it is indicative of fungal infections
What is manna antigen a test for?
invasive Candida
How is sepsis managed?
- send blood cultures
- within 3hrs: start antibiotics and bolus at 30cc/kg of crystalloid if lactate > 4
- within 6hrs: start pressors if needed to maintain MAP and repeat a lactate
What are considered first and second line pressors for sepsis?
- levo is first
- vaso is second
How does dopamine work as a pressor?
- low dose: dopamine receptors in kidney
- medium dose: B1 receptor activation
- high dose: alpha receptor activation
How does levo act as a pressor?
a1, some B1
How does epi act as a pressor?
a1, B1, B2
How does vasopressin work as a pressor?
activation of V1 receptors
How does dobutamine work as a pressor?
B1 activation (increases cardiac output but can have vasodilatory effects)
What is the mechanism of action of milrinone?
- PDE inhibitor and increases cAMP
- has inotropic and vasodilatory effects
What acid-base disturbance do patients with PE most often have?
respiratory alkalosis due to tachypnea secondary to hypoxia
What are the indications for thrombolytics with PE?
hemodynamic instability or right heart strain on echo
What is a a trendelenburg procedure?
pulmonary embolectomy
Pulmonary wedge pressure is really a measure of what?
end diastolic LV volume
How is cardiac index calculated?
as cardiac output/BSA
What happens to systemic vascular resistance in patients with hemorrhagic shock?
it increases
What happens to CVP and PWP in patients with cardiogenic shock?
they both increase
How is oxygen delivery calculated?
cardiac output x [Hb x SaO2 x 1.34 + (PaO2 x 0.003)]
How is oxygen consumption calculated?
cardiac output x (PaO2 - PvO2)
How is the oxygenation extraction ratio calculated?
= O2 consumption / O2 delivery
= {CO x [Hb x SaO2 x 1.34 + (PaO2 x 0.003)]} / [CO x (PaO2-PvO2)
= [Hb x SaO2 x 1.34 + (PaO2 x 0.003)] / (PaO2 - PvO2)
Which anticoagulant can be removed via dialysis?
dabigatran
How is dabigatran reversed?
dialysis or praxbind
How is warfarin reversed?
vit K, FFP, or PCC
PCC can be used to reverse which anti-coagulants?
- full effect for warfarin
- partial effect for Eliquis and Xarelto
What is the respiratory quotient?
- a ratio of CO2 production/O2 consumption
- it is a helpful measure of nutrition because it identifies carbohydrate overfeeding in intubated patients, which results in higher CO2 production and difficulty weaning
How is the respiratory quotient interpreted?
- 0.7 indicates fat metabolism
- 0.8 indicates protein metabolism
- 1.0 indicates carbohydrate metabolism
- > 1 indicates overfeeding
How is nitrogen balance calculated? How is it interpreted?
= protein intake/6.25 - (urine nitrogen + 4)
- positive means the patient is in an anabolic state, negative means they’re in a state of catabolism
How many calories in a gram of…
- carbohydrate
- dextrose
- lipids
- protein
- carbohydrate: 4
- dextrose: 3.5
- lipids: 9
- protein: 4
Carbohydrates should make up __% of non-protein calories.
75%
Lipids should make up __% of non-protein calories.
25%
What is a person’s daily protein requirement?
1-2 g/kg/day
When should TPN be considered?
5-7 days without enteral nutrition
What is the differential for hemoptysis after Swan Ganz balloon inflation?
ruptured pulmonary artery
What is the treatment for tornadoes de pointes?
IV mag
What mediates acute rejection?
T-cells
How do cyclosporine and tacro work?
they are calcineurin inhibitors that block IL2
