NIV in “Sympathetic Crashing Acute Pulmonary Edema”

18 Feb

While working on this topic in stumbled on the 1st podcast of EMCrit.com, the famous blog by Scott Weingard. He was talking about “Sympathetic Crashing Acute Pulmonary Edema”…SCAPE! Well, this is exactly what I have been talking about for the last few weeks and I am gonna borrow this definition from him. These crashing patients are very dyspneic, have crackles and due to the high levels of (nor)epinephrine their blood pressure is very high.

As you know from my previous posts these patients with SCAPE need high doses of nitrates, no morphine and the diuretics you can throw in the coffee of that irritating doctor or nurse who keeps telling you that an initial dose of 100 ug/min of NTG is way too much in these patients. But what about the oxygen? CPAP, BiPAP or just a non-rebreather mask (NRM)?

What do we want to see in SCAPE? A quick reduction in shortness of breathing and a reduction in intubation and mortality, without any side-effects. So is NIV op for the challenge and does it show benefit over the conventional oxygen therapy?

There is too much literature out there go over in detail, but I was very lucky to find 2 great meta-analyses  about the topic. In the first (1) the pooled RR for mortality was  0.61 (0.41-0.91 95% CI), when comparing NIV (CPAP or BiPAP) vs. “standard care”.  The pooled RR for intubation was 0.43 (0.21-0.87 95% CI).  While this sounds very convincing, only respectively 1 and 2 out of the 6 articles showed a significant reduction by itself. When comparing CPAP vs BiPAP no statistical difference was found concerning intubation and mortality.

Review NIV-APE

In the other (2), more articles were found that looked at NIV vs standard therapy, but there was a great overlap between the articles discussed in both meta-analyses. The OR (95% CI) for CPAP vs standard therapy was 0.32 (0.17, 0.59) regarding intubation and 0.33 (0.18, 0.59) regarding mortality.  For BiPAP a trend was seen in favour of BiPAP, but no significant reduction in mortality of intubation, when compared to standard therapy.  When comparing CPAP vs BiPAP almost no difference was found in the pooled data.

breathlessness NIV APE

So there seems to be a reduction in mortality and intubation while using NIV, but what about the shortness of breath. Don’t forget that these patients are in great distress and all they want in your ED is breath normal again! So off course you give them the nitrates!!! but does NIV help reducing the breathlessness compared to standard therapy? Kelly, et al (3) did a prospective study. Next to the frusemide, 5mg buccal nitrate and morphine the patients were randomized to receive 60% of oxygen via Venturi mask vs CPAP with PEEP of 7.5 cmH2O. They found a significant decrease for breathlessness after 1 and 6h in the CPAP group! Furthermore no treatment failure and side-effects were mentioned and a trend in reduction of hospital mortality was seen.

Conflicting data has been reported about mortality and early successful treatment (defined in this article as RR<23/min,SpO2>90% & pH>7.35), by Crane, et al. (4) They found a higher early treatment success rate in the BiPAP group, when compared to standard therapy and CPAP, but the CPAP had a significant lower mortality rate. This might be explained by the fact that the CPAP group was more acidotic, but otherwise it is difficult to explain.

Conclusion:

While there seems to be a lot of evidence supporting NIV in SCAPE, the debate is still there. Sure, NIV has shown to improve oxygenation, increase cardiac output and reduce work of breathing. But most articles weren’t able to find a significant decrease in mortality and intubation. On the other hand, when the data was pooled in a meta-analysis it could be estimated that early application of NIV might decrease mortality by 39% and intubation by 57% (1).

Then there is also the discussion about CPAP vs. BiPAP. Well, I am a CPAP-man and will keep on using it. If you are more of a BiPAP-man….go ahead, I won’t stop you. Initially there were some concerns about its use because of one study suggesting an increase in myocardial infarctions rate when compared to CPAP. (5) However, in this study significantly more patients with chest pain were in the BiPAP group and the one study looking specifically at MI’s didn’t find a different (6).

So we see a trend towards a reduction in intubation and mortality. That’s not bad, but for me (and for patient also I bet) the most important effect is the reduction in breathlessness! If this is without any reduction in intubation and mortality, fine by me…as long as there is no increase!  These patients are scared and need treatment…..fast. So don’t leave them drowning.

——

We almost have come to the end of discussing the ESC guideline regarding Acute Pulmonary Edema! The next post will be an overview of everything we discussed about and….We are gonna flip the guideline! See you then!

Egon Zwets!

references NIV in APE

Advertisements

2 Responses to “NIV in “Sympathetic Crashing Acute Pulmonary Edema””

  1. Karl Mattingly February 18, 2013 at 23:00 #

    Great point of view! I fully agree and I think that people need to be more open about discussing these issues.

  2. Iwan February 19, 2013 at 01:30 #

    Another great one Egon!
    About CPAP vs BiPAP, I think it’s really simple: If you have a patient with pulmonary oedema and hypoxemia, all you need is CPAP. If, on the other hand you also have hypercapnia, then use BiPAP (or intubate).

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s