3 DISCUSSION
The patient in this case had been diagnosed with asthma many years previously. To remove the endotracheal tube gently without irritating the airway following the surgery, we changed the patient’s posture under deep anesthesia. During this process, the patient severely bit the tube and we were unable to provide ventilation for several minutes. Negative pressure pulmonary edema occurred owing to severe negative intrathoracic pressure due to airway obstruction caused by the severe biting of the endotracheal tube, and a large quantity of bloody secretion was released into the intubation tube. At first, NPPE was suspected, and treatment was actively performed, including fluid restriction, diuretic administration, exhalation positive breathing, and 100% oxygen administration. Chest imaging performed after transfer to the intensive care unit showed diffuse haziness in the right lung field and persistent hemoptysis. Bronchoscopy findings showed no abnormal airway damage with the exception of bloody secretion in the bronchus or airways.
According to Mondoni et al. 5 early bronchoscopy helps detect bleeding sources. They suggested that if there is rebleeding, the bronchoscopy must be performed again to examine the damaged airway area. Hemoptysis caused by damage to the airways due to temporary negative pressure is reported to naturally cease over time.
Shankar et al. 6 reported airway bleeding and hemoptysis caused by temporary intrathoracic negative pressure resulting in airway damage from airway obstruction due to various causes. This may be misdiagnosed as pulmonary edema. The authors suggested that hemoptysis may be caused by aspiration pneumonitis, airway injury, polyps, arteriovenous malformation, and tumors.
Prost et al. 7 reported that NPPE was a rare (5%, 6/112) cause of DAH. Contou et al. 1 surveyed 149 patients in whom DAH was suggested over 36 years (1980-2015) and found that 18 cases (12%) of DAH occurred in 15 patients through NPPE. According to the study, almost 17 cases (94%) showed acute respiratory failure with no other organ failure or circulatory failure. Hemoptysis was found in 17 out of 18 cases (94%) and was the most common symptom, but in only one case was more than 200 ml per day observed. Anemia was observed in 10 cases (56%) and the average hemoglobin reduction was 1.5 g/dl. It was reported that 9 cases (50%) satisfied the DAH triad (hemoptysis, anemia, and pulmonary infiltrates). In this case, hemoptysis was the main symptom and anemia was not severe. The authors reported that 16 cases (89%) showed alveolar or interstitial opacity of both lungs, and only two cases (11%) demonstrated alveolar or interstitial opacity in the right lung. In the present case, diffuse opacity was observed in the right lung.
Schwarz et al. 8 reported pulmonary hemorrhage after NPPE in surgical patients for the first time, and Goldenberg et al.9 reported two patients with tricuspid and pulmonary insufficiency among six post-laryngospasm NPPE patients. Dolinski et al.3 reported pulmonary hemorrhage in patients with mild tricuspid regurgitation due to increased pulmonary artery pressure after NPPE. In this case, the patient had evidence of trivial MR in the transthoracic echocardiography performed before surgery, but the clinical symptom was not specific. It is thought that a more detailed examination is needed to determine whether this mild MR was the cause of unilateral DAH in this case, but such an examination was not performed in this patient. In 2016, Han et al. 10 reported negative pressure pulmonary hemorrhage that occurred after laryngospasm in the postoperative period. In 2016, Choe et al. 11reported DAH after trans-femoral cerebral angiography in patients taking clopidogrel, and there is a potential for DAH associated with neuro-intervention in patients with hemoptysis and respiratory failure. It was argued that patients who are taking anticoagulants should carefully taper off the medicine prior to surgery and then begin it again during or after surgery. In addition, the author stated that it is better to protect less damaged lungs through active lung management such as oxygen therapy, bronchodilators, endotracheal intubation, and mechanical ventilation management in the treatment of patients with DAH.
NPPE by acute upper respiratory tract obstruction has been reported in about 11% of cases. 12 Risk factors for postoperative obstruction include obesity, short neck, obstructive sleep apnea, upper respiratory surgery, hypertrophy, and difficulty in tracheal intubation. While any factor that can cause gastrointestinal obstruction can cause NPPE, the most common cause of NPPE during anesthesia is postoperative laryngospasm.
It is reported that NPPE occurs within a few minutes of airway obstruction and improves quickly after a day or two with active treatment. Steroids, diuretics, and bronchodilators are known to help, but their actions in these cases are not clear. 12
Papaianou et al. 13 reported that hemoptysis caused by NPPE, which occurs during obstruction of the upper airways, such as cases of laryngospasm, may be caused by negative-pressure tracheobronchial injury or alveolar-capillary disruption. It is also said that tension applied to the pulmonary-capillary wall may be caused by alveolar-capillary membrane rupture. The authors stated said that administration of succinylcholine (Sch) 80 mg and administration of an unconsciousness inducing agent can prevent airway obstruction caused by laryngospasm. 13 Both laryngospasm and biting were possible causes of the patient’s airway obstruction in the present case. The authors chose sugammadex for muscle relaxation reversal instead of Sch in this case, focusing more on the visible biting rather than laryngospasm as the cause of airway obstruction, and the patient quickly stopped biting and was able to undergo ventilation.
Young male athletes are known to be at risk, and the syndrome occurs rarely in patients with endotracheal intubation, but may also occur if the patient bites the endotracheal tube during waking.14 Additional causes include excessive endotracheal or laryngeal aspiration, as well as abnormal positioning of the mask. However, there are few reports of pulmonary hemorrhage accompanied by NPPE due to upper respiratory tract obstruction. 1,8
Schwartz et al. 8 reported that at the end of surgery, negative intrathoracic pressure caused by upper airway obstruction after extubation causes hypoxic respiratory failure. The authors noted that post-anesthetic laryngospasm, strangulation, hanging, foreign body airway obstruction, and OSA may be factors associated with NPPE.
Contou et al. 1 reported that the mechanisms of development of NPPE were negative pressure formation in the thoracic cavity, increased hydrostatic pressure in systemic and pulmonary capillaries, and mechanical stress in the alveolar capillaries.
According to Contou et al., 1 first, - 2 ~ - 5 cmH2O intrathoracic negative pressure (- 100 cmH2O in severe cases) increases venous return from peripheral blood vessels to the right atrium, simultaneously increasing pulmonary blood flow, increasing trans-mitral capillary pressure, and increasing pulmonary capillary and alveolar cavity pressure and stress. The hydrostatic pressure rises. These changes increase the trans-capillary pressure gradient, and the fluid exudes into the interstitial space. The author also reported that elevated central venous pressure interferes with lymphatic blood circulation.
Second, according to Contou et al., 1 the systemic pressure increases owing to the secretion of norepinephrine due to hypoxemia, hyper carbon dioxide, and anxiety, which increases the amount of pulmonary blood flow. These effects reduce right ventricular dilatation, ventricular wall movement, and cardiac output. As the vascular resistance of the whole body increases, the resistance of the left ventricular wall increases, and the left ventricle prevents the blood flow.
Lastly, the authors reported that effusion from capillaries due to physical alveolar-capillary membrane damage caused alveolar edema and bleeding.
Unilateral pulmonary edema is a very rare complication. This complication is mainly reported in cases of heart disease such as severe mitral insufficiency or congestive heart failure, and there are few reports in patients without heart disease. The syndrome can be caused by prolonged lying on the lateral side or by excessive administration of fluids in this position, and can occur after treatment in cases such as pleural effusion or pneumothorax, or after re-expansion. MacLeod syndrome, unilateral pulmonary agenesis, talc pleurodesis, trauma, epilepsy, upper airway obstruction, pulmonary venous obstruction from mediastinal fibrosis, post-lobectomy, unilateral mainstem intubation, nitrogen mustard, and heroin-related pulmonary edema, and pregnancy may all be causes of the syndrome. 15 The patient in the present case was not in the lateral position and had no specific trigger except for asthma from which he had been suffering for a long time.
As such, negative unilateral pulmonary edema and unilateral pulmonary hemorrhage may result from many causes. In patients with acute respiratory failure with hemoptysis and unilateral alveolar opacity, if clinical findings are not consistent with pneumonia, it is important to determine the presence of heart disease. Rapid initiation of active treatment is important.
In summary, DAH is mainly caused by airway obstruction after surgery in young and healthy male athletes. The patient in the present case demonstrated acute respiratory failure accompanied by hemoptysis and alveolar opacity on both sides, along with bilateral bleeding from both sides and no bronchial damage. It is known that in older individuals, there is a high possibility that there will not be enough negative pressure to destroy the pulmonary capillaries, but the patient in this case was an elderly male patient who had been diagnosed with asthma 70 years earlier, considered to be at increased risk and with damaged sensitivity to the endothelial tissue of the bronchioles.
In a 78-year-old man treated with asthma for a long time, change to the supine position at the end of general anesthesia resulted in severe hypoxic respiratory failure, increased airway pressure, and intra-tracheal tube after acute upper respiratory obstruction owing to severe endotracheal tube biting. The patient experienced a large amount of bloody secretions. Ultimately, the patient was discharged without complications owing to appropriate treatment for negative pressure pulmonary hemorrhage that occurred after endotracheal tube biting. Anesthesiologists should take care not to induce airway irritation during emergence of asthma, because DAH accompanied by NPPE was caused in this case by airway irritation in an older patient with asthma without known risk factors.