Intubating Asthmatic Patients

Asthma is Greek for panting, which is a fitting translation for a patient that presents with a severe asthma exacerbation. We try to avoid intubating these patients because they are prone to compilations such as pneumothorax, mucus plugging, and increased morbidity and mortality. 

However, there are specific situations when you may consider intubating an asthmatic patient. One reason is that your patient may not be improving despite maximal medical therapy, such as BIPAP, albuterol, ipratropium, magnesium, epinephrine/terbutaline, ketamine, etc. Another reason is that your patient may now be altered, and have worsening work of breathing, and vital sign abnormalities. Remember that a “silent chest” is a poor prognostic indicator; you may not hear wheezing because they are not moving any air. 

If you choose to intubate, there are tricks to maximize your success and optimize your management of your patient on the vent. 

• Use a large ETT (8-9) because it reduces airflow resistance and can facilitate procedures later (such as bronchoscopy). 

• Ketamine is a useful induction agent because of its bronchodilatory effects. It may also be useful if you choose delayed sequence intubation. 

• High airway pressures can cause hypotension after intubation, so consider giving volume if there is a current or prior history of hypotension. 

• If hemodynamics are compromised consider giving an epinephrine drip. It is considered a systemic bronchodilator that can provide hemodynamic support as well as bronchodilation. 

• Keep a low respiratory rate when bagging or on the vent (6-8 breaths/min). Giving them time to exhale will decrease the chances of air trapping and pneumothorax. Another way to do this is to increase the I:E time (1:4 or 1:5). 

• If the vent is alarming, troubleshoot (DOPES mnemonic) but be suspicious for mucus plugs, pneumothorax, or breath stacking. If they are breath stacking, disconnect them from the vent and push on their chest to help them fully exhale.  

A quick note about auto-PEEP and breath stacking: Auto-PEEP refers to trapping gas in the lungs during respiration. This occurs when one breath can’t be fully exhaled before the next inhalation. This trapped gas causes additional positive pressure, known as “auto-PEEP” in the chest which is typically higher than the PEEP set on the ventilator. This process predisposes patients to develop a pneumothorox. 

Thanks for reading!

Ariella

CXR- Consolidation or Atelectasis?

Here is a quick guide on differentiating consolidations vs atelectasis on chest x-ray.

The reason that we can differentiate structures on x-rays is due to differences in density. For example, the lungs are air-filled and appear black whereas the ribs, vertebrae, and heart are solid and appear white. 

Consolidation: consolidation represents the replacement of alveolar air with fluid, blood, pus, or other substances. There are 3 lobes of the right lung, the upper, middle, and lower lobes. The right middle lobe sits next to the heart border. The left lung has 2 lobes, the upper and lower lobe. The left upper lobe sits next to the heart (image 1). If you have an obscured right heart border, it may indicate consolidation of the right middle lobe (image 2). Similarly, an obscured left heart border may indicate a consolidation in the left upper lobe (image 3). The lower lobes of each lung sit next to the hemidiaphragm. If you cannot make out a hemidiaphragm, it may suggest that there is something of similar density, such as a consolidation, in that lower lobe.

On a normal lateral chest x-ray, the vertebrae should get progressively darker as you get closer to the bases, known as the "more black sign". The vertebrae located near the apex of the lung have overlying muscles, making them appear white, compared to those at the bases that have overlying air, which makes them appear darker (image 4). You should also be able to make out 2 hemidiaphragm on the lateral x-ray with sharp costophrenic angles.

Atelectasis: Atelectasis refers to the collapse of a lung portion. On a normal x-ray, ⅓ of the heart is located on the right and ⅔ of the heart is located on the left side of the chest (image 5). In atelectasis, you will see the mediastinum shift towards the affected side due to volume loss, causing the heart and trachea to shift (image 6). In addition, the unaffected lobe on the ipsilateral side will be hyperlucent as a result of compensatory hyper-expansion. The rib spaces on the affected side may also be closer together when compared to the contralateral side and there may be an elevation of the ipsilateral hemidiaphragm. 

Tip: don’t be fooled by a rotated cxr. Rotation can be assessed by measuring the distance between the medial edges of the clavicles to the vertebral spinous processes. They should be equal or near equal.

Thanks for reading! 

Ariella 

References: 

https://radiopaedia.org/courses/emergency-radiology-course-online/pages/1417

https://radiopaedia.org/articles/lung-atelectasis

POTD: Can I Go Home With My PE?

Congrats, Maimo Fam! You ordered the correct CT and you subsequently found that Pulmonary Embolus (PE). ...Now what?

This POTD was requested for further discussion on risk stratifying patients that can potentially be discharged with a pulmonary embolus. Let's talk about the PESI Score!

Pulmonary Embolism Severity Index (PESI)

The PESI is designed to risk stratify patients who have been diagnosed with a PE in order to determine the severity of their disease. This can help physicians make decisions on the management of those patients who could potentially be treated as out-patient, as well as raise concern for those who are determined to be high-risk and could benefit from higher levels of care.

In the setting of a patient diagnosed with PE, the PESI can be utilized to determine mortality and long term morbidity. For those determined to be very low risk (score ≤ 65), all studies showed a 30-day mortality <2%. In the validation, low risk (Class I and II) had a 90-day mortality of 1.1%. The non-inferiority trial demonstrated Class I and II could have been treated as outpatients assuming no other issues.

Sounds great, but what's the catch? Although the PESI tool has been externally validated, there are a few pitfalls to be aware of.

In the setting of a patient with renal failure or severe comorbidities, clinical judgement should be used over the PESI, as these patients were excluded in the validation study.

The PESI score determines risk of mortality and severity of complications.

The score does not require laboratory variables.

It is meant to aid in decision making, not replace it. Clinical judgement should always take precedence.

The PESI score determines clinical severity and can influence treatment setting for management of PE. Class I and II patients may possibly be safely treated as outpatients in the right clinical setting.

Class I - Scores ≤ 65 indicate very low risk.

Class II - Scores of 66-85 indicate low risk.

Class III - Scores of 86-105 indicate intermediate risk.

Class IV - Scores of 106-125 indicate high risk.

Class V - Scores >125 indicate very high risk.

Again, studies show PE patients with PESI class I or II seem safe to manage as outpatients. But as always, cOrReLaTe ClInIcAlLy.

Some final thoughts:

Social situation should also be taken into account before considering outpatient management (including the appropriate administration of anticoagulants).

Given low mortality of low risk PE, outpatient management would save significant funds over hospitalization (cited as $4,500 per avoided admission).

The non-inferiority trial showed successful and safe outpatient management of Class I and II patients.

As with other tools and scores we use in the ED, use your gut and your clinical judgement. These tools are to help you in your decision, but you're the only one that can put all the pieces of your patient's clinical puzzle together. I have faith in all of you to do what's best for your patient.

References:

Aujesky D, Obrosky DS, Stone RA, et al. Derivation and validation of a prognostic model for pulmonary embolism. Am J Respir Crit Care Med. 2005;172:1041-1046.

https://www.mdcalc.com/pulmonary-embolism-severity-index-pesi

https://wikem.org/wiki/Pulmonary_embolism