There are few things as scary in the Emergency Department as a crashing asthmatic. The stakes go even higher when we are talking about intubating asthmatics. In this podcast we are joined by Dr. Andrew Phillips, and ED intensivist and founder of the awesome board review suite EM Coach, to talk about staving off intubating in asthmatic patients, how to safely intubate them in the Emergency Department, and most importantly, how to manage them after the tube.

Intubating Asthatics The SimKit Podcast


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There is a lot that goes in to preventing intubation in the asthmatic and management once they are tubed. So we created a helpful infographic to keep on you.

Before we talk about intubating asthmatics, we need to talk about steps to prevent this from happening in the first place. Dr. Phillips notes two important history points that help you know the direction a patient may go. They include: 1) if the patient has ever been intubated before and 2) when their symptoms started- longer is worse. In preventing intubation, there are several medications we should to use to to prevent the intubation:

  • Beta agonists and anticholinergics– we are going to use the staple of albuterol and likely ipratropium in our nebs. For get about breath actuation here, fill the neb reservoir with albuterol-ipratropium combo (say 3 blisters worth) and let it flow. Not that in these very tight patients these agents may not be getting to the lower respiratory tract.
  • Magnesium– note we are not giving this med like we typically do for repletion. We are giving 2 grams magnesium over 20 minutes. Now the hypotension that may come from this typically is usually of little concern here as these patients have high catecholamine states and are hypertensive.
  • Epinephrine– we are looking at 03.-0.5 mg SubQ or IM every 20 minutes for up to three doses. An older alternative is terbutaline 0.25 mg subQ also every 20 minutes for up to three times.
  • Steroids– while we recognize that by mechanism of action these agents may not be fast enough to stave off intubation, it is still important to give early. For agent, dealer’s choice here. Some us solumedrol 20 mg IV and some methylprednisolone 125 mg IV.

Assessing Patient Response

When assessing if you interventions are working, Dr. Phillips notes two ways to look at things:

  1. Ask the patient– Many of these patients have had experience with severe asthma exacerbations and you can simply ask them, “How are you doing? Are you tiring out?” And take that feedback seriously.
  2. The gas improves– These patients are breathing hard through narrow airways. They will often blow down their CO2 and will have a respiratory alkalosis. If the VBG starts to normalize, then the patient may be tiring out and going in the wrong direction.

These elements will help us know when we have crossed the line in the sand and need to move to intubation.

Preparing For Intubation

If our above kitchen sink is not working, we need to prepare for intubating the asthmatic. We note two additional things we consider. The first is ketamine which is used for both its bronchodilatory effects and for preoxygenation. This can facilitate a delayed sequence intubation (DSI). The second is non-invasive positive pressure ventilation (NIPPV) which Dr. Phillips recognizes may not help the pathophysiology but is a great way to preoxygenate. This is particularly helpful as we have dissociated the patient and are moving toward paralysis. After paralyzing the patient, we can see it work when the machine notes no more patient-triggered breaths and it is all machine-triggered breaths.

Dr. Phillips notes that after intubation these patients should likely remain paralyzed to optimize ventilatory settings.

The intubated asthmatic is the patient that, after spending a looong time working the patient and eventually intubating them, you carry on with the rest of the department needs and are called back to the room 15 minutes later for a code. We can prevent this by doing the following:

  1. Keep focus on the patient– We have to avoid the pull to care for the rest of the department and return to the intubated asthmatic frequently- check their hemodynamics, assess the vent settings, etc. These initial vent settings are as follows:
  2. I:E ratios– We want the patient to get the air in quickly and give them plenty of time to breath out. This involves setting an inspiratory time (Itime) to expiratory time (Etime) ratio of 1:4 to 1:6. Having as low a respiratory rate as allowed by the patients CO2 can help this.
  3. Inspiratory pressure and time– These asthmatic patients require complex vent management. Dr. Phillips notes this often requires a transition from an ED vent to an ICU vent. With this, we again want to get the breath in as quickly as safely possible. The vents will allow this in one of two ways- inspiratory time or max flow pressure. If time, we want a very short inspiratory time (ex: 0.5 seconds). If pressure, we want to allow very high max flow pressure (100 cm H20!) to get the breath in quickly.
  4. Plateau pressure– To make sure our patient is safe with the vent settings we put in, we want to assess their plateau pressure. We want this number under 30 cm H20. This is an inspiratory hold. We also want to trend the expiratory hold and make sure their intrinsic PEEP is not rising, which predisposes to breath stacking.
  5. Watch for breath staking– pay attention to their breath waveform and make sure all the air is getting out. If they are gradually pulling lower tidal volumes or the patient’s hemodynamics are worsening, consider unplugging the patient from the vent with pressure on the chest to get the air out.

We want to use the kitchen sink to stave off intubating asthmatics. To do this, we use albuterol and ipratropium nebs, magnesium 2 gms over 20 minutes, epinephrine 0.3-0.5 mg IM (or subQ) and our steroid of choice.

When we decide to intubate these patients, we want to be quick and facile. We can use ketamine to induce and NIPPV to preoxygenate so we note immediately when our paralytic kicks in to intubate.

After the intubation is when the real fun starts. We need vent settings including the following:

  • Close attention to the patient after intubation.
  • Big I:E ratios of 1:4 to 1:6 with a slow as tolerated respiratory rate.
  • We get these I:E by quick inspiration by setting a fast inspiratory time or high inspiratory pressure.
  • Plateau pressure
  • Watch for breath stacking

REFERENCES

  1. Spiteri MA, Millar AB, Pavia D, Clarke SW. Subcutaneous adrenaline versus terbutaline in the treatment of acute severe asthma. Thorax. 1988 Jan;43(1):19-23. [pubmed]
  2. Victoria MS, Battista CJ, Nangia BS. Comparison between epinephrine and terbutaline injections in the acute management of asthma. J Asthma. 1989;26(5):287-90. [pubmed]
  3. Schwartz HJ, Trautlein JJ, Goldstein AR. Acute effects of terbutaline and epinephrine on asthma. Double-blind crossover placebo study. J Allergy Clin Immunol. 1976 Oct;58(4):516-22. [pubmed]
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