Uso da ventilação não invasiva em síndrome do desconforto respiratório agudo grave por inalação acidental de cloro: um relato de caso / Use of noninvasive ventilation in severe acute respiratory distress syndrome due to accidental chlorine inhalation: a case report

RESUMO A síndrome do desconforto respiratório agudo é caracterizada por lesão pulmonar inflamatória difusa, classificada em leve, moderada e grave. Clinicamente observam-se hipoxemia, opacidades bilaterais na imagem pulmonar e diminuição da complacência pulmonar. A sepse está entre as causas mais prevalentes (30 - 50%). Dentre as causas diretas de síndrome do desconforto respiratório agudo, a inalação de cloro é uma causa incomum, gerando, na maior parte dos casos, irritação de mucosas e vias aéreas. Apresentamos um caso de síndrome do desconforto respiratório agudo grave após inalação acidental de cloro em piscina, sendo utilizada ventilação não invasiva como tratamento com boa resposta neste caso. Classificamos como síndrome do desconforto respiratório agudo grave baseado na relação pressão parcial de oxigênio/fração inspirada de oxigênio < 100, embora a classificação de Berlin seja limitada em considerar pacientes com hipoxemia grave manejados exclusivamente com ventilação não invasiva. A taxa de falha da ventilação não invasiva nos casos de síndrome do desconforto respiratório agudo está em torno de 52%, estando associada à maior mortalidade. As possíveis complicações do uso da ventilação mecânica não invasiva com pressão positiva na síndrome do desconforto respiratório agudo seriam o atraso para a intubação orotraqueal sendo a mesma realizada em uma condição clínica pior e um alto nível de pressões de suporte, somados a esforços inspiratórios profundos, gerando elevados volumes correntes e pressões transpulmonares excessivas, que contribuem para injúria pulmonar associada à ventilação. Apesar disto, alguns estudos mostraram diminuição nas taxas de intubação orotraqueal em pacientes com síndrome do desconforto respiratório Agudo com baixos escores de gravidade, estabilidade hemodinâmica e ausência de outras disfunções orgânicas.

ABSTRACT Acute respiratory distress syndrome is characterized by diffuse inflammatory lung injury and is classified as mild, moderate, and severe. Clinically, hypoxemia, bilateral opacities in lung images, and decreased pulmonary compliance are observed. Sepsis is one of the most prevalent causes of this condition (30 - 50%). Among the direct causes of acute respiratory distress syndrome, chlorine inhalation is an uncommon cause, generating mucosal and airway irritation in most cases. We present a case of severe acute respiratory distress syndrome after accidental inhalation of chlorine in a swimming pool, with noninvasive ventilation used as a treatment with good response in this case. We classified severe acute respiratory distress syndrome based on an oxygen partial pressure/oxygen inspired fraction ratio <100, although the Berlin classification is limited in considering patients with severe hypoxemia managed exclusively with noninvasive ventilation. The failure rate of noninvasive ventilation in cases of acute respiratory distress syndrome is approximately 52% and is associated with higher mortality. The possible complications of using noninvasive positive-pressure mechanical ventilation in cases of acute respiratory distress syndrome include delays in orotracheal intubation, which is performed in cases of poor clinical condition and with high support pressure levels, and deep inspiratory efforts, generating high tidal volumes and excessive transpulmonary pressures, which contribute to ventilation-related lung injury. Despite these complications, some studies have shown a decrease in the rates of orotracheal intubation in patients with acute respiratory distress syndrome with low severity scores, hemodynamic stability, and the absence of other organ dysfunctions.

Acute accidental exposure to chlorine gas: Clinical presentation, pulmonary functions and outcomes.

Background. To study the clinical presentation, pulmonary functions and outcomes in subjects who were accidentally exposed to chlorine gas. Methods. Prospective observational study of 64 patients who sustained acute accidental exposure to chlorine gas during a leak in the chlorination system of the public bathing pool of a temple. Results. The major presenting symptoms and signs included acute dyspnoea (100%), chest discomfort (100%), cough (97%), eye irritation (88%), giddiness (72%), vomiting (46%), and heaviness in the head (44%); tachycardia (100%), tachypnoea (96%) and polyphonic wheezing (28%). All patients were managed in the emergency room with humidified oxygen inhalation and beta-2 agonist nebulisation and 52 were discharged within six hours. Twelve patients were severely affected and required hospitalisation; three of them were admitted into the intensive care unit. Three patients developed pulmonary oedema six to eight hours following admission. Pulmonary function testing (n=12) at presentation revealed obstructive defect in eight and mixed obstructive-cum-restrictive defect in four patients. The mean duration of hospital stay was 5.1±2.1 days. None of the patients died. Reactive airway dysfunction syndrome (RADS) was observed in three of the 12 hospitalised patients, who complained of manifested persistent cough that lasted for three months period following discharge. Serial pulmonary functions recovered to normal range by the end of the six months in all patients and remained so at one-year follow-up. Conclusion. Acute exposure to chlorine gas is an uncommon, but important public health hazard and can cause RADS, acute lung injury and pulmonary function abnormalities , which are reversible on prompt and appropriate management.

Acute accidental exposure to chlorine fumes--a study of 82 cases.

Eighty-two patients were hospitalized following an accidental exposure to chlorine. All patients presented with dyspnoea and cough. The other symptoms included irritation of throat (53.6%), irritation of eyes (42.3%), headache (29.2%), abdominal pain (26.8%), vomiting (24.3%) and giddiness (9.7%). All of them had bronchospasm and 5 (6%) had cyanosis at the onset. An x-ray of the chest revealed patchy infiltrates in 3 (3.85%) and hilar congestion in 2 (2.44%). Pulmonary function tests showed an obstructive pattern in 27.4%, restrictive in 3.25% and mixed in 53.2%. Pulmonary functions were normal in 16.1% of the patients. Bronchoscopy revealed tracheobronchial mucosal congestion in all cases, hemorrhagic spots in 35.7%, erosions and ulcers in 12.5%. All patients were treated with oxygen, aminophylline, hydrocortisone and antibiotics. Haematemesis (n = 1) and pulmonary oedema (n = 2) developed 12 hours after the admission. Two other patients developed pneumonia 48 hours later. All patients recovered satisfactorily. On follow-up 16 patients had no sequelae after one year. Pulmonary functions were normal in 5 patients after 3 years of follow-up.

Acute chlorine poisoning. A study of 84 cases.

Eighty four cases with acute chlorine poisoning who reported between 1/2 hour to 2 hours after exposure were studied. A majority presented with features of upper respiratory tract involvement like irritative cough (70 cases) and oropharyngeal pruritus (60 cases). Bronchospasm was present in 15 cases. None of them had any residual impairment of pulmonary function 4 weeks after exposure.