Critical Care Flashcards
Review the mnemonic for RSI.
SOAPME
- S: suction
- O: oxygen
- A: airway (ETT in expected size and one smaller, stylet, syringe, laryngoscope) and alternative airways (mask and bag)
- P: position patient (end of bed, sniff position, towel roll)
- M: medications (sedative like ketamine, paralytic like rocuronium, and post-sedation like propofol) and monitors (telemetry, pulse-ox)
- E: EtCO2 sensor
- Make sure RT is present and ventilator is ready
What ABG findings are suggestive of impending respiratory failure in an asthma attack?
Hypoxemia and hypercarbia
What are the three reasons intubation worsens hypotension?
- Positive-pressure ventilation decreases RV filling
- Vagal response
- RSI meds
How does pulse oximetry work?
Pulse-ox devices shine a red light and an infrared light through a part of tissue. Oxygenated blood absorbs a lot of red light but not much IR light. Deoxygenated blood does not absorb much of either IR or red light. By comparing these you can get a sense of what part of hemoglobin is oxygenated.
It also uses Beer’s law and Lambert’s law.
Beer’s law states that absorption of light is proportional to the concentration of a substance.
Lambert’s law states that the absorption is proportional to the distance traveled through a substance. Because the distance traveled through tissue changes ever so slightly with pulsations, you can calculate the arterial component of blood.
This is calibrated on healthy volunteers breathing diluted oxygen mixtures.
What does the PI next to the plethysmography graph stand for?
Perfusion index
This is a measure of the signal strength.
___________________ is a more accurate spot to obtain SpO2 in vasoconstricted states.
The ear or forehead
Pulse oximeters are not reliable in which patients?
Those with non-pulsatile flow: ECMO and LVAD patients.
Pulse oximeters have what lag time?
5-15 seconds
How can you identify a vasodilated state on plethysmography?
A steep upslope, a tall peak, a steep downslope, a long PTT, and a high PI indicate a vasodilated state.
What is the pulse transit time?
It’s the time from R-wave peak (systole) to the next plethysmography peak, which physiologically is the time it takes blood to get from the heart to the tissues.
A long PTT indicates a vasodilated state.
What is hypoxia and hypoxemia?
- Hypoxia: insufficient oxygen delivered to tissues
- Hypoxemia: insufficient oxygen in blood
What are the five causes of hypoxemia?
- Low partial pressure of inspired oxygen (such as from going up in altitude)
- Low alveolar ventilation (drug overdoses, CNS injury, neuromuscular problems, and chest wall stiffness)
- Diffusion limitations (pulmonary edema, pulmonary fibrosis)
- V/Q mismatch (obstructive lung diseases, pulmonary emboli)
- Shunt (cardiac defects, AVMs, severe pulmonary disease where blood is not oxygenated)
Increased A-a gradient that does not normalize with supplemental O2 is _______________.
shunt
Diffusion limitations and V/Q mismatch will normalize. Decreased partial pressure of O2 and decreased ventilation will have normal A-a gradients.
Volume control mode is also called ______________.
assist control volume (AC-VG)
Pressure control mode is also called ______________.
assist control pressure (AC-PC)
If you’re setting volume (say, in volume control AC-VG mode), what are typical tidal volumes?
400-500 mL
What are rise time and inspiratory time?
Inspiratory time is the time that a breath is delivered over. Rise time is the time it takes the ventilator to achieve the peak pressure. Because of this, rise time is only on PC modes.
What is PRVC?
Pressure-regulated volume control
This is a mode in which you set a tidal volume and a maximum pressure. It tries to achieve the TV but has a pop off pressure to avoid barotrauma.
Explain the settings in SIMV-PS.
- RR: this is the rate of breaths that are fully ventilated (i.e., not PS breaths). The patient will get all of these breaths directed by your settings (PC or VG), and then they can get any additional breaths on top of this rate guided by the PS settings.
- PC/VG: you can have either mode in SIMV. This will be the settings for the RR breaths – not the PS breaths.
- PS: this is the pressure support that the patient will get for the breaths they initiate on top of their RR. It is written as the additional pressure they get on top of PEEP. So if the PIP of their RR breaths is 22 and they have a PEEP of 8, then they would need a PS of 14 in order to get the same inspiratory pressure during PS breaths.
- PEEP: same as always
- FiO2: ditto
Review the flow rates of these access types:
- Triple lumen catheter (with 16 gauge x1 and 18 gauge x2)
- 18 gauge IV
- Cordis (8.5 Fr)
- 16 gauge IV
- Triple lumen catheter (with 16 gauge x1 and 18 gauge x2): ~7 L/hr
- 18 gauge IV: 6.0 L/hr
- Cordis (8.5 Fr): 7.6 L/hr
- 16 gauge IV: 13.2 L/hr
In which patients is therapeutic hypothermia least helpful?
- PEA arrests
- Brain bleeds
- Significant trauma
- Hypotensive despite pressors
- Pediatric patients
Sepsis resuscitation fluids are _______ mL/kg.
30
Review the 1-hour sepsis bundle items.
Orderset: ED Adult Sepsis
- Lactate
- Blood cultures
- Broad-spectrum antibiotics
- Fluids for hypotension or lactate > 4
- Vasopressors if hypotensive or elevated lactate after 30 mL/kg fluids
You must remeasure lactate in sepsis if it is greater than ________.
2
Review the new diagnosis fo sepsis (from the 2016 Surviving Sepsis Campaign).
A life-threatening organ dysfunction caused by a dysregulated host response to infection
Organ dysfunction can be identified as an acute change in total SOFA score ≥2 points consequent to the infection.
The baseline SOFA score can be assumed to be zero in patients not known to have preexisting organ dysfunction.
A SOFA score ≥2 reflects an overall mortality risk of approximately 10% in a general hospital population with suspected infection. Even patients presenting with modest dysfunction can deteriorate further, emphasizing the seriousness of this condition and the need for prompt and appropriate intervention, if not already being instituted.
What level of hypotension triggers the fluid indication in the sepsis bundle?
Two reliable* BPs w/ MAP < 65
- This means values that you trust and that are new for the patient. If a patient is always low then document it.
Why is the sepsis bundle important to complete?
Studies have shown that patients who complete the sepsis bundle have a significant improvement in mortality.
If you reach ___ mcg/min of norepinephrine, consider starting a second pressor (typically vasopressin).
5
If a patient is having clinically important tachyarrhythmias on norepinephrine or epinephrine, consider switching to _______________.
phenylephrine
For CMS compliance with sepsis, you only need to document _______________.
that you examined the patient, what weight you used for IV fluids, and the post-fluids exam
Also, document why you deviated from protocol in your MDM (such as why antibiotics were given after before cultures or why fluids were not per protocol)
What should you document for sepsis patients?
Go to the sepsis tab (in the bar with Study Review, Care Everywhere, etc.) and then type .sepsisexamtotal to pull the flowsheets into your MDMD.
If you don’t want to use the navigator, you can also use the .uncmcsepsisexam dot phrase in your note.
If you are struggling to ventilate a patient, then consider _______________.
paralysis
Review the mnemonic for hypoxia in intubated patients.
If your intubated patient becomes hypoxic, don’t be a DOPE:
- Dislodgement of the tube (check for a change in depth, bilateral breath sounds, capnography, and consider a CXR)
- Obstruction (suction for secretions)
- Pneumothorax (listen for bilateral breath sounds, check a CXR)
- Equipment failure (check the pulse ox, circuit tubing, and ventilator)
__________ is first-line for cardiogenic shock, septic shock, and neurogenic shock.
Norepinephrine
Epinephrine is first-line for which type of shock?
Anaphylactic
What is the dose of norepinephrine?
1-30 mcg/min
Some places do weight-based dosing.
Neosynephrine is which pressor?
Phenylephrine
Which pressor has no extravasation risk?
Phenylephrine
It can actually be given subcutaneously.
________________ can vbe given if other pressors are causing significant arrhythmias.
Phenylephrine (Neosynephrine)
What are pressor doses of dopamine?
5-10 mcg/kg/min for beta targeting
10-20 mcg/kg/min for alpha targeting
Which pressor is not titratable?
Vasopressin
It is standard to be 0.03 units/minute. UNC used to be 0.04 units/minute but recently switched.
Which receptor does vasopressin act on to increase BP?
V1
Remember the “V2 is tubules”.
The highest extravasation risk pressor is ___________.
vasopressin
You need a central line to give this.
Dopamine’s brand name is __________.
Intropin
What is the shock index?
Shock index is HR/SBP. This value in healthy people is < 0.9. If it is greater than this it can indicate shock.
What are the two types of heat stroke?
Exertional and non-exertional
Exertional heat stroke is the classic young athlete or military cadet who overexert themselves in extreme heat.
Non-exertional heat stroke is typically seen in people with comorbitidies that prevent them from escaping heat (think old demented lady in non air conditioned place or young child in a car).
How should you assess treatment of heat stroke?
The patient’s GCS should improve rapidly with cooling. If they don’t then think of something else.
True or false: you should correct heat stroke to normal temperature.
False, just get it to lower fever levels, like 101
How can you treat heat stroke if it fails cold rags, ice packs, misting?
Body bag full of ice
A key clinical finding of heat stroke is ________________.
AMS
What are typical beginning vent settings?
- Mode: The usual start mode is Pressure-Regulated Volume Control (PRVC), because the person you have intubated is most likely paralyzed and sedated from RSI.
- FiO2: always start at 100% and wean down because they are likely to be hypoxic from RSI.
- RR: typical settings are 10-12, though this can vary. If someone has an obstructive disorder (bad asthma or COPD), then you want to do a lower rate with a higher I:E ratio to avoid breath stacking. If a person has bad ARDS or edema then you may want to do a higher rate (such as 15-20) with a lower TV (like 6 instead of 8) to avoid volutrauma.
- Tidal volume: typically 8 ml/kg unless concerned for ARDS or obstructive disorders in which case you want to do less (like 6) to avoid volutrauma and breath stacking, respectively.
- Peep: 5 is typical
What temperature do you infuse warmed fluids at to treat hypothermia?
105° - 110° F
Describe an apnea test.
This test is used to help determine brain death. You disconnect someone from a ventilator with their sedation turned off. Keep NC or other supplemental oxygen turned on at 6 L/min. You then draw an ABG 8 minutes later. If they did not take a breath and they are hypercapnia to a PaCO2 greater than 60 mm Hg or 20 mm Hg greater than baseline it is considered positive.
Note: these are the prerequisites for the test.
- Normothermic
- Normotensive
- Euvolemic
- Eucapnic
- Absence of preceding hypoxia
What medicine is given to those who are brain dead to help preserve organs for donation?
Desmopressin
Brain death induces central diabetes insipitus (failure of the posterior pituitary to release ADH) so people with brain death commonly have excess urine output. Thus, ICU doctors attempt to maintain euvolemia with IV fluids desmopressin, and pressors to preserve organs.
What are the dosing ranges of epinephrine for vasopressor use?
0.014 - 0.5 mcg/kg/min (so doses work out to 1 - 35 mcg/min)
What doses are “phenyl sticks”?
50 or 100 mcg
What is the dosing range of gtt phenylephrine?
0.25 - 6.0 mcg/kg/min (so 20 - 360 mcg/kg/min)
What is the dosing range of gtt dopamine?
2 - 50 mcg/kg/min
The dose of gtt vasopressin is _________.
0.04 U/min
What is the dose of dobutamine?
0.5 - 40 mcg/kg/min (though greater than 20 mcg/kg/min is only recommended in salvage therapy for heart transplant)
What is the dose of milrinone?
0.125 - 0.75 mcg/kg/min
Review the DOPES mnemonic for hypoxia in ventilated patients.
Displacement: Is the tube in the right spot? Check ETCO2 and CXR
Obstruction: Suction the patient.
Pneumothorax
Equipment failure? Disconnect the ventilator and bag to see if this corrects things.
Stacked breaths: in those with obstructive disease, allow for longer exhalation
How do the rates complications of central lines vary by placement in the IJ, subclavian, and femoral veins?
Femoral vein has the highest rate of infection.
Subclavian has the lowest rate of infection.
Subclavian has the highest rate of PTX.
Review the dosing of propofol.
Initial bolus dosing: 1-1.5 mg/kg
Follow-up bolus dosing: 0.5 mg/kg
Drip dosing: 20 - 75 mcg/kg/min
Review the dosing of ketamine.
Bolus dosing: 1.5 mg/kg
Drip dosing: 1.5 mg/kg/hr
What is a disadvantage to ketamine gtt sedation?
There are not pre-made bags.
In what two settings would you use ketamine for continuous sedation?
Hypotension and asthma
What are the sedation doses of fentanyl and versed?
Bolus: 100 mcg fentanyl and 2 mg Versed
Gtt: 100 mcg/hr fentanyl and 2 mg/hr Versed
You can give what electrolyte you augment pressors?
Calcium
Smooth muscles (that mediate vasoconstriction) are calcium dependent.
Review the process of calculating a delta gap.
Calculate a delta gap in those in who have anion gap metabolic acidosis:
- Delta gap = calculated anion gap - expected anio gap + actual bicarb
If the delta gap is > 24 then they have a superimposed metabolic alkalosis. If it is less than 20 they have superimposed metabolic acidosis.
Example: 7.25 / 20 / 35 / 6
Na: 135
Cl: 85
Bicarb 6
This is a metabolic acidosis (academic due to low bicarb). By Winter’s formula they have inadequate compensation. The anion gap is 44. And 44 - 12 (the calculated minus the expected) is 32. Then 32 + 6 (the calculated gap minus the expected gap plus the measured bicarb) is 38.
Altogether, the above example is a primary anion gap metabolic acidosis with a superimposed respiratory acidosis (or inadequate compensation) with a superimposed metabolic alkalosis.
If a person is severely acidotic and hypotensive, which vasopressor should you consider?
Vasopressin
The catecholaminergic pressors are less effective if a person is severely acidotic, but vasopressin is unaffected by pH status.
A 2021 trial showed that early head-to-toe CT in unexplained out-of-hospital cardiac arrest identified a cause of arrest in ____% of patients and a life-threatening effect of resuscitation in ___% of patients.
39; 16
An SpO2 of 90% corresponds to what PaO2?
about 80 mm Hg
What factor may make patients in anaphylaxis not respond to epi?
Beta blocker use
Consider early glucagon if someone on beta blockers is hypotensive refractory to epinephrine.
ARDS net recommends what tidal volume for ARDS patients?
6-8 mL/kg of IBW
For those without ARDS, you can use what tidal volume?
6-10 mL/kg of IBW
To obtain a plateau pressure, perform an ____________.
inspiratory hold
Peak plateau pressure should be less than ________.
30 cm H2O
In which patients would you accept plateau pressures greater than 30 cm H20?
Obese patients (because of the increased chest wall weight)
Plateau pressures are a surrogate for ___________.
lung compliance
What I:E ratio would you aim for in an asthmatic or COPD patient?
1:3 - 1:4
If the vent flow diagram shows that the inhalation begins below the horizontal axis that divides inhalation from exhalation, then this is a sign of what?
Breath stacking
The ideal body weight for a 5 ft 2 in female is what?
The ideal body weight for a 6 ft 2 in male is what?
50 kg
80 kg
Thus, a 6 mL/kg of IBW for a short female is 300 mL. An 8 mL/kg for a tall male is 640 mL.
How can you confirm a central line placement with an US?
Agitate saline and inject while doing a cardiac US. Positive bubbles = placed correctly.
Intubated asthmatics who are not doing well may need _______.
ECMO
What are goal PIPs for lung protective ventilation?
Less than 40 cm H2O
Importantly, patients need to be ___________________ to get a plateau pressure.
passive on the vent (if they’re fighting the vent you will get falsely elevated plateau pressures)
If you are going from BiPAP to intubation, what should you use to guide minute ventilation?
The minute ventilation of their BiPAP!
What are normal peak pressures?
25-30 cm H2O
normal plateau pressures are _________.
about 20 cm H2O
True or false: patient’s needing cardiac catheterization should not undergo therapeutic cooling 2/2 risk of coagulopathy.
False
Cooling can co-occur with cardiac cath.
The TTM2 trial showed what about targeted temperature management?
That normothermia is equivalent to targeted hypothermia.
The most common rhythm of pediatric cardiac arrest is what?
Asystole
Which vasopressin is best to use in those with pulmonary hypertension (e.g., massive PE, decompensated PAH)?
Vasopressin
Vasopressin does not increase pulmonary vascular resistance, so it supports the RV with increased preload (from increased SVR) without increasing RV afterload.
Which vasopressin takes the longest to reach peak effect and the longest to wear off?
Milrinone
It takes hours to reach peak effect and hours to wear off (whereas the other vasopressors are essentially instantaneous).
Review the things you can do to resuscitate a hemodynamically unstable person with RV failure.
- Be judicious with fluids. If their RV is failing, giving too much fluid can congest their lungs and worsen the failure.
- Decrease pulmonary vascular resistance. Pulmonary vasodilators like supplemental oxygen, inhaled NO, inhaled epoprostenol, and inhaled milrinone can help relieve high RV afterload. Also, correcting acidosis can help decrease pulmonary pressures too.
- Give vasopressors early, particularly vasopressin, to support RV preload without increasing RV afterload.
- Be careful with intubation. Only intubated if you have to and maximally resuscitate beforehand if you do.
Which pressors should be used in a hypotensive patient with gut ischemia?
Milrinone, dobutamine, or dopamine (because those impact thee mesenteric vasculature the least)
What adverse effects does therapeutic hypothermia cause?
Hyperglycemia (cold causes insulin resistance)
Diuresis
Hypocalcemia
Dysrhythmias
Flow (such as gas through a circuit) is proportional the ___ power of the radius of the conduit.
4th
Increasing the ____________ does not fix hypoxia in a shunt.
Increasing the ____________ does not fix hypercarbia in dead space ventilation.
FiO2
rate
True or false: proper ventilation settings can fix V/Q mismatch.
False
In shunt, no amount of setting changes will correct hypoxia. In dead space ventilation, no amount of MV changes will correct the dead space ventilation.
True or false: hypercarbia results from decreased airway ventilation.
False
It results from decreased alveolar ventilation.
Review Sarah Crager’s bellows analogy for hypercarbia.
The ventilatory capacity of the lungs is like a bellows that blows air out. Insufficient ventilation can result from one of three failures of the bellows:
- The nozzle is too small
- The accordion of the bellows is too stiff (decreased lung compliance such as from ILD or infiltrate in the interstitial or alveolar spaces)
- The operator is too weak (neuromuscular weakness)
Review the PaO2 : FiO2 ratios of mild, moderate, and severe hypoxic respiratory failure.
Mild: 200-300
Moderate: 100-200
Severe: < 100
If the volume on a ventilator does not return to zero, this means what?
Breath stacking
Top on the flow loop is ______________.
inhalation
How does pneumothorax affect peak and plateau pressures?
Elevation of both
A PTX knocks out both the alveoli and the airways (if severe).
If the flow loop does not return to normal, this either indicates breath stacking or _____________.
leak in the circuit
Why is mechanical ventilation less efficient than natural ventilation?
- Increased resistance: the ETT is much narrower than the mouth, larynx, and trachea (Poiseuile’s law)
- Increased dead space ventilation
Why does the efficiency of mechanical ventilation decrease at higher RRs?
Each breath has a set amount of dead space. If you increase the amount of breaths per minute, you increase the amount of dead space ventilation.
Normal I:E ratio is what?
1:2
How do you set I:E ratio on vents?
Change the I time
Normal inspiration happens through ____________ inspiratory flow.
decelerating
What does PRVC accomplish?
Two things:
- It allows for decelerating inspiratory flow, which is more physiologic.
- It prevents high pressures.
In metabolic acidosis with hyperglycemia, should the sodium be corrected before calculating the gap?
No, because the Cl is also diluted
How does BiPAP change afterload and preload?
It decreases both.
PPV increases intrathoracic pressure which decreases venous return (and thus decreases preload). Decreased preload decreases the end-diastolic LV volume which is the marker of afterload (not SVR).
PIP should be _______________.
15-20 cm H2O
What are the three zones of the aorta (for REBOA)?
I: left subclavian to celiac
II: celiac to renals
III: renals to
What is shock index?
HR/SBP
Normal person at rest: 60/120 = 0.5
Normal person under stress: 120/120 = 1.0
In general, shock index greater than 1.0 predicts increased mortality.
Review the concentrations of epinephrine in cardiac arrest and anaphylaxis.
In cardiac arrest, epi is stored in 1 mg in mL syringe (0.1 mg/ml). In anaphylaxis it is concentrated 1 mg in 1 mL.
What are the diagnostic criteria for abdominal compartment syndrome?
Pressure greater than 20 mm Hg and new abdominal organ dysfunction not otherwise explainable
What imaging findings are typical of fat embolism?
Diffuse ground-glass opacities
True or false: absence of respiratory variation in a chest tube is always abnormal.
False
If the lung is expanded there will often not be respiratory variation (because the eyelets can be occluded by lung and pleura).
What is the sepsis-induced coagulopathy score?
It’s a score that uses platelet count, INR, and SOFA score to help predict which septic patients may develop DIC (and thus warrant early anticoagulation).
What is the minimum goal PaO2 for treating ARDS (in the ARDS net protocol)?
55 mm Hg
What duration of immobility (in hours) is considered a risk factor for DVT?
8 hours
True or false: base excess reflects respiratory and metabolic acidosis.
False
Base excess is purely based on metabolic derangement – not respiratory.
Positive base excess reflects what derangement?
Metabolic alkalosis
Why is base excess used in trauma?
Trauma patients are more likely to be single-problem patients (i.e., trauma is their only malady). Abnormal base excess in a trauma patient is a good indicator of trauma severity. In a MICU patient, they are more likely to have multiple metabolic derangements and base excess is less helpful.
What is important to know about K-Dur (the tablets of potassium)?
It is long acting. If you need to correct it imminently – like hypokalemic DKA – then you should give solutions. They taste bad but are much faster.
