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Treating Pneumothorax With Oxygen (Again)

The topic of treating pneumothorax with high inspired oxygen concentrations keeps coming up! I’ve written about this a few times in the past, and the literature I found supporting the practice was terrible. Some readers brought three more studies to my attention that support it, so I’m going to take the next three days to see if there is any hope for this practice.

Today’s paper used a rabbit model where each animal was given a complete pneumothorax by the injection of 15cc (!!) of air into one hemithorax. The authors then let the pneumothorax resolve using room air or 30%, 40%, or 50% FIO2. Each group consisted of 10 rabbits, and repeat chest xrays were obtained every 6-8 hours to follow resolution.

The statistical analysis was interesting and unusual. Because the authors were studying the time to resolved pneumothorax with higher inspired O2, they were looking for a test that would analyze an “ordered alternative.” The Jonckheere-Terpstra test was used, which I have never heard of, but I’ll assume it’s the legitimate one to use.

The figure at the top of this post shows the results. Looks promising right? There was a big improvement from room air to 30%, but lesser improvement using higher oxygen concentrations. The error bars (standard error of the mean) are remarkably tight, but this makes sense since xrays were only being taken every 6-8 hours.

The two big problems with this study are that: 1. they’re rabbits and it only takes 15cc of air to drop the entire lung, and 2. standard xray is being used to measure resolution. Trying to pick apart the exact time to resolution of a 15cc pneumothorax is very difficult, and to try to do it with a test that we know is not great at detecting small amounts of air even in big humans just doesn’t work. 

Bottom line: Fancy statistics and nice looking results don’t make up for an animal model that doesn’t necessarily correlate with humans and deriving results using an inaccurate diagnostic test. Tomorrow, I’ll look at a paper in the Journal of Pediatric Surgery to see if it fares any better.

Related posts:

Reference: Resolution of experimental pneumothorax in rabbits by graded oxygen therapy. J Trauma 45(2):333-334, 1998.

Thanks to Stephanie Taft MD at Regions Hospital for finding these fine studies for me.

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Best Of: High Inspired O2 Is Not An Effective Pneumothorax Treatment

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The use of high concentrations of inspired oxygen seems to be a time-honored technique for trying to avoid chest tube insertion for pneumothorax. But does it stand up to scrutiny, or is this just an urban legend?

This recommendation is based upon a single case report involving 8 patients in 1983! Six patients with a pneumothorax of less than 30% showed a decrease in size of 4.2% per day on average. The two patients with pneumothoraces larger than 30% did not respond. A response was only seen with oxygen administered by a partial nonrebreather mask, not by nasal cannula.

What’s the problem? First, this is a very small case report. There were no controls, so it is entirely possible that the resolution rate without treatment was the same as that seen in this report. Furthermore, this study was performed prior to the availability of chest CT. Therefore, the true size of the pneumothoraces is only a guess since volumetric calculations could not be performed. It is not possible to distinguish a 4% change in the size of a pneumothorax by regular chest xray (click here for more details).

The bottom line: If the patient needs supplemental oxygen for management of other pulmonary conditions, then administer it. It is not indicated as an independent treatment for pneumothorax, and its use for this condition should be abandoned!

Related posts:

Reference: Noninvasive treatment of pneumothorax with oxygen inhalation. Chadha TS. Respiration 44(2):147-52, 1983

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Yet Another Paper on Treating Pneumothorax With Oxygen?

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Back in February, I thought I closed the door on using high inspired oxygen to try to speed up the resolution of pneumothorax (see related post below). I’ve just run across another attempt which is equally as bad!

This article was published in the Journal of Pediatric Surgery in 2000. The authors randomly divided 27 rabbits into three groups: room air, 40% O2, and 60% O2. Each was given a complete pneumothorax and received chest xrays twice a day. The average time to resolution was measured in each group.

At first glance, it appears that the higher O2 groups resolve faster. But wait, something’s fishy here! In the room air group, the complete pneumothorax went away on its own in 5 days. This doesn’t really happen in people. And in the 60% group, it disappeared in a day and a half! Miraculous!

Oh, and incidentally, a quarter of the rabbits died before completion of the study.

Bottom line: At first glance, these results sure look promising. However, they are rabbits, and they don’t act like people, let alone children! And the resolution times are unrealistic for humans. I still do not recommend the use of high inspired oxygen in an attempt to resolve a pneumothorax. Either some kind of tube is needed for larger volumes (small caliber if air only, bigger if blood is present), or it will go away on its own if the pneumothorax is small.

Related posts:

Reference: Zierold et al. Supplemental oxygen improves resolution of injury-induced pneumothorax. J Pediatric Surg 35(6):998-1001, 2000.

General

High Inspired O2 Is Not An Effective Pneumothorax Treatment

Leave a comment

The use of high concentrations of inspired oxygen seems to be a time-honored technique for trying to avoid chest tube insertion for pneumothorax. But does it stand up to scrutiny, or is this just an urban legend?

This recommendation is based upon a single case report involving 8 patients in 1983! Six patients with a pneumothorax of less than 30% showed a decrease in size of 4.2% per day on average. The two patients with pneumothoraces larger than 30% did not respond. A response was only seen with oxygen administered by a partial nonrebreather mask, not by nasal cannula.

What’s the problem? First, this is a very small case report. There were no controls, so it is entirely possible that the resolution rate without treatment was the same as that seen in this report. Furthermore, this study was performed prior to the availability of chest CT. Therefore, the true size of the pneumothoraces is only a guess since volumetric calculations could not be performed. It is not possible to distinguish a 4% change in the size of a pneumothorax by regular chest xray (click here for more details).

The bottom line: If the patient needs supplemental oxygen for management of other pulmonary conditions, then administer it. It is not indicated as an independent treatment for pneumothorax, and its use for this condition should be abandoned!

Related posts:

Reference: Noninvasive treatment of pneumothorax with oxygen inhalation. Chadha TS. Respiration 44(2):147-52, 1983