When I was a resident, every vent lecture either put me to sleep or left me dazed and bewildered. I gave a lecture of that ilk when I started working after fellowship. I had become part of the problem. I decided there must be a way to make vent management more understandable and if not interesting, at least bearable.
This lecture was up on the soon to be defunct EMCrit Lecture site. It offers a path to managing any patient on the ventilator in the ED. I have tried to simplify as much as possible while still maintaining an evidence-based approach.
This is Part II, it deals with the obstructive strategy. Last week, we spoke about the strategy for patients with lung injury.
Your goal with these patients is to let them have adequate time to breathe out.
There are only 4 things you need to remember for an obstructive patient
- Vt (Tidal Volume) = 8 ml/kg, don't mess with it
- Flow Rate = 60-80 lpm, shortens insp times (this really doesn't do much good, and super-high IFRs should not be used. Increasing IFR will also increase peak pressure)
- Resp Rate = Lung protection, start at 10 work your way down if necessary
- FiO2/PEEP = Oxygenation, should need much O2 (40%)m I recommend PEEP of 0, but certainly keep it less than 5
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First, read my Ventilator Article in the Annals of EM [Managing-Initial-Vent-ED]
Then, print out this Handout for the Dominating the Vent Series
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Professor
Nassau University Medical Center
No conflicts of interest (coi).
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Hey Scott,
Great lecture, I liked the format.
One question- do you paralyze all your intubated asthmatics? Theoretically this should decrease metabolic demand and lower CO2 production, but I haven’t found any data on this.
Thanks,
Rich Chang
Hennepin C0unty Medical Center
Rich,
Thanks.
I don’t ever paralyze, but I sedate and analgeze the heck out of the asthmatic patient to the point where there is no spontaneous breathing and they are essentially rock-like. This has all the advantages of paralysis and none of the problems.
scott
Very helpful lecture.
Thanks, Sherly!
Thanks Scott for the great lecture. I just have a question regarding deadspace. Like you stated, Va for a normal CO2 when not intubated is 60cc/kg/min and double that for intubated patients. What if the patient is not intubated but trached instead? Does it matter if I use 120cc/kg/min to include the ventilator tubing/circuit deadspace? Please advise. Also, I would love to hear your explanation for not using PEEP in COPD patients? Besides decreased venous return and increased in intrathoracic pressure, are there any other reasons?
Keep up the great work.
Tom
Keep it simple. Works well, and easy to remember.
Thanks!
thanks for listening!
One concept that I am struggling with is in treating acute copd exacerbations . They have “obstructed” lungs and are hypercapneic. So do you set the rate at 10, 18, 36 or somewhere in between and adjust based on Plateau pressures and blood gasses?
Also would you use Zeep or a Peep of 5?
Thanks
Titrate RR to normalize pH, not PaCO2 as most of these pts are chronic retainers. If Plat is high, accept low pH. ZEEP is fine, 5 is essentially not doing anything negative; would not go beyond that.
Hi Scott.
I understand the concept of not having to use PEEP for someone with obstructive respiratory distress. However, I also have read that using PEEP at approximately 80% of the estimated auto-PEEP decreases the work of breathing needed to initiate a spontaneous breath and increases patient comfort.
I was wondering what your opinion of this rationale was and whether you often adjust the PEEP above 5. Additionally, if you’re using NIV with a COPD patient, do you use the same approach?
Thanks!
Hi Scott, Great lecture, thanks for all the education. I want to share a trick I learned recently when I got a call from a community hospital that was transferring us an intubated asthmatic that they couldn’t ventilate, asking for help with the ventilator. This forced me to realize that there is one ventilator prescription that will provide safe, idiot-proof ventilation for most COPD/asthma patients… a universal vent prescription. It is Pressure Control mode with 5 cm PEEP, 30 cm Pressure Support, 60% FiO2, respiratory rate of 14/min (to generate a peak pressure of 35cm). For this to work the… Read more »
ummm, not so much. Pressure control in no way protects from the problems of hyperinflation. Hyperinflation problems come from your resp rate, not the mode of ventilation. PC leaves you with a situation in which the patient may have variable and insufficient tidal volumes. So instead of decreased venous return (pneumothorax doesn’t happen anymore with low tidal volume/low rr ventilation) you get a patient who gets no oxygen to their alveoli. If you like PEEP, knock yourself out. As I mentioned in the podcast, there has never been a documented benefit.
I was hoping to avoid the pressure-cycled vs. volume-cycled ventilation debate. I’ve gone between institutions which preferred one or the other, and the only constant is that everyone is convinced that their way is best. Vent mode is religion in the ICU. Let me flesh out my argument with a thought experiment in the style of quantum mechanics, because ultimately this comes down to physics. Imagine two identical asthmatics, Mr. AC and Mr. PC, are intubated at a small rural ED and placed on volume assist-control ventilation and pressure control ventilation, respectively. The hospital doesn’t have an ICU so they… Read more »
Great info Josh. It has been my experience that for severe asthmatics pressure control ventilation with PEEP adjusted for air-trapping works intially. However, if the condition of the patient deteriorates it generally will require a paralytic/anesthetic to prevent the patient from arrest due to severely inadequate gas exchange and/or acidosis beyond permissive > 7.10. Permissive hypercapnia is definitely a winning strategy for initial vent management. For those who have COPD and severe emphysema, once a patient has air-trapped enough due to tachypnea, they will become hypercarbic and drowsy/obtunded. It’s been my experience that these patients are easier to manage, since… Read more »
Hey,
Thanks for the great overview! I have 1 question:
Could you comment on the distinction between the flow rate and I:E ratio? If my understanding is correct (and assuming the Vt isn’t changing), the flow rate would naturally increase with decreasing I:E ratios (e.g. going to 1:4 or 1:5) because more volume would need to get into the lungs within a shorter period of time. Is that not the case?
I love these ‘back to basics’ topics (your acid-base series is another favorite). Keep up the great work!
-brent
Brent, There are two ways to decrease the I:E. Decrease the resp rate or increase the flow rate. If you locked the RR and the Vt then yes the flow would need to increase. This is fair less effective than decreasing RR.
In reference to “Dominating the Vent.” I have a patient in the ICU due to a scooter vs car accident. He has huge blebs from his emphysema, but now he has ARDS. I’m a third year medical student and am trying to understand what his ventilator settings should be according to the video. Currently, his PEEP is at 12, his RR is at 34, and his pH is around 7.3 with a high CO2 around 90. Also, he is not air trapping. Thanks.
Does those numbers for plateau pressure apply to pediatric population as well?
Dr. Weingart,
As a respiratory therapy student, I’m not comfortable with the idea of ZEEP, unless we are using it for spontaneous breathing trial or flail chest. Since we are using positive pressure ventilation and not atmospheric diaphragmatic negative pressure breathing, Isn’t the patient lacking the intrinsic PEEP to prevent atalectrauma and distal airway collapse?
Physiologic PEEP is a myth. You can start here with Tobin:
https://www.atsjournals.org/doi/full/10.1164/rccm.201201-0050ED
for additional references. You are at the perfect spot in your career to question everything you are told by instructors and see how much is a chain of myths and what is actually based on a foundation of evidence. If you change to that mindset you have an opportunity to break the cycle of bad information relayed in continuous chain from teacher to learner.
Great topic and strategies; I just cannot handle the bro-iness of your speaking. I have no disclosures.
Vent setting is difficult. This talk really helped to simplify and approach problems in the vent. Thank you Dr. Weingart!