▲Figure 3 CT of chest on Day 9: No abnormal density shadow was
observed in both lungs. No obvious abnormality was observed in
mediastinum and bilateral armpit.
DISCUSSION
Hyperbaric
oxygen as a routine treatment for acute carbon monoxide poisoning can
not only convert the carboxyhemoglobin in mitochondrial cytochrome to
oxygenated hemoglobin during carbon monoxide poisoning, but also reduce
the permanent neurological and emotional effects of carbon monoxide
poisoning[4]. In addition, hyperbaric oxygen therapy is particularly
important in preventing long-term sequelae,it can reduce acute
mortality and mortality after one year[5, 6] .In addition to acute
carbon monoxide poisoning, we also found successful cases of
pneumomediastinum treated with hyperbaric oxygen[7-14].
In this case, the main symptoms
were acute carbon monoxide poisoning, drowsiness, bilateral pneumonia,
and pneumomediastinum. After 11 hours of acute carbon monoxide
poisoning, the patient was placed in 1.3 ATA chamber with compressed
air. HBOT protocol was 70 minutes at 1.3 ATA with both 20 minutes of
compression and decompression. After only one treatment, it was found
that his consciousness was recovered after the poisoning. Computed
tomography shows that pneumomediastinum and bilateral pneumonia were
also reduced. The next day, the treatment was extended to 100 minutes at
1.3 ATA with both 20 minutes of compression and decompression. And the
same HBOT for the next week.
In another case report we found
that hyperbaric oxygen therapy in a patient with pneumomediastinum due
to diving[8]. Four hours after he was injured, the patient was
placed on the chamber that pressurised to 1.3 ATA, Symptoms improved
after 60 minutes of 100% oxygen inhalation via a built in breathing
system (BIBS) mask. Also, in another report, a 13-year-old boy with a
helium-filled brain embolism and pneumomediastinum received 40 minutes
of air at 165 fsw, 100 percent oxygen for 3 hours at 60 fsw, and then
100 percent oxygen at 30 fsw. The patient’s reported symptoms completely
disappeared[7].Combined with the above case and the case in this
paper, we assume that the patient may not require such a extensive
recompression to achieve the goal of symptom relief. Maybe 10 fsw is
enough to make his symptoms go away.
In an example of a patient who
died due to a diving accident, it was clear that the patient was in
urgent need of HBO treatment due to bilateral tension pneumothorax and
pneumomediastinum caused by DCS. However, due to the shortage of
hyperbaric oxygen rooms in the local area and the shortage of personnel,
the patient could not receive timely treatment even when he was in an
important indication[15].
These examples undoubtedly show
that in the face of patients with pneumomediastinum, timely HBO
treatment is very important. After the primary treatment plan is clear,
the parameter setting of hyperbaric oxygen therapy is also a question
worth studying. Whether we can achieve the best treatment effect through
the minimum parameter setting, so as to reduce the complications caused
by hyperbaric oxygen therapy. The 1.3 ATA HBO therapy used in this case
has not been found to have recurrence or complications in the follow-up
of the patient within half a year after discharge.
The common pneumomediastinum is usually caused by mechanical
ventilation[16] or DCS, but in this case, neither of these reasons
exists. Given the presence of COVID-19 pneumonia, we considered that
COVID-19 had caused his symptoms of pneumomediastinum. It has been
speculated that the pathophysiological mechanism of its occurrence is
diffuse alveolar damage and alveolar rupture, leading to interstitial
emphysema and air tracking along the bronchoalveolar sheath to the
mediastinum[17]. It is mentioned in this article that high serum
lactate dehydrogenase may be positively correlated with the development
of pneumomediastinum in COVID-19 patients[17].
A study from China reported two
patients with COVID-19 pneumonia, patients were treated with 1.5 ATA HBO
with an oxygen concentration of more than 95% for 60 minutes per
treatment, once a day for one week. For both patients, dyspnea and
shortness of breath were immediately alleviated after the first HBO2
treatment[18]. Gorenstein et
al reported a study of 20 COVID-19 patients treated with 2 ATA of
hyperbaric oxygen therapy for 90 minutes daily and propensity matched
controls. The results show that the in-hospital mortality rate and time
to mechanical ventilation are higher in propensity matched control group
comparing to cases treated with HBOT [19]. In America, 5 COVID-19
patients received hyperbaric oxygen therapy for 90 minutes at 2.0 ATA
between 13 and 20 April 2020.The final results demonstrated that all the
patients recovered without the need for mechanical ventilation[20].
Although the parameters in these reports are different from the 1.3ATA
we used, the final results are all positive. When acute carbon monoxide
poisoning was combined with pneumomediastinum due to COVID-19, we found
that inhalation of hyperbaric oxygen had the desired therapeutic effect.
This provides a new clinical evidence to treating not only acute carbon
monoxide poisoning but also the complications of COVID-19 with HBO.
In addition, computed tomography (CT) can be an important complement to
timely diagnosis and identification of the causes of respiratory
impairment and lung complications associated with COVID-19[21].
CONCLUSION
In conclusion, this case demonstrates a clear benefit of hyperbaric
oxygen therapy in the treatment of pneumomediastinum caused by COVID-19
pneumonia and carbon monoxide poisoning.
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