DISCUSSION
We present a patient with ARDS due to acute lung injury related to Midwakh. Dokha is manufactured by drying tobacco leaves, mixed with herbs and spices to enhance the flavor. It is smoked through a small pipe called Midwakh, which has three parts, a mouthpiece, a stem, and a bowl (image 1). The bowl can contain approximately 0.5 grams of dry tobacco, enough to finish one session in 2 inhalations; Therefore, an individual ends up smoking Midwakh 20-25 times a day.
Smoking Midwakh is increasing in the Gulf and particularly in the UAE7, among the adolescent and school students1.It is the most commonly used ATP in UAE, next only to Cigarette on overall tobacco use8. Nicotine levels in Midwakh tobacco products were 170.76%, 218.07%, 128.57%, and 193.33% higher in comparison with cigarettes, chewing tobacco, snuff tobacco, and electronic cigarettes respectively and its tar content is the highest when compared to shisha and cigarettes2. Midwakh tobacco products contains harmful levels of cobalt, chromium, cadmium, iron, and lead. In addition to these, carcinogens and Central nervous system (CNS) depressants were found9,10 .Traditional Midwakh pipes contain no filters; hence these toxicants can quickly enter the lungs. Midwakh smokers may add herbs, spices, dried flowers, fruits, bark, and leaves of native plants (like the Damas tree leaves) to tobacco. Nevertheless, the effects on these combinations and the byproducts on combustion have never been reported.
Toxic inhalational lung injury may result in a spectrum of respiratory disorders like bronchopneumonia, pulmonary edema, interstitial lung disease, reactive airways dysfunction syndrome, obstructive airway disease, and Bronchiolitis Obliterans Organizing Pneumonia (BOOP), as the triggering agents could be single or multiple. Fatal cases following significant exposure were associated with laryngeal edema, airway obstruction, non-cardiogenic pulmonary edema/ARDS, and secondary infection in the setting of the diffuse airway and pulmonary parenchymal damage11. They also described the resolution of initial acute pneumonia to be followed by the gradual onset of airway obstruction, which has to be watched during the follow-up.
The clinical presentation and radiological findings, including CT scans, were quite similar to the E‐cigarette/Vaping‐associated Lung Injury (EVALI) outbreak in the USA. Patients with EVALI present with acute, severe respiratory distress with findings typical of a chemical-induced pneumonitis after using E-Cigarette or vaping products12. Symptoms like cough, shortness of breath, fever can rapidly worsen within 24-48 hours of initial presentation, as happened in our case13.
In addition to antibiotics, patients with EVALI were treated by systemic steroids to reduce the inflammatory response. As per the CDC, steroids showed an improvement in the clinical condition in almost 82% of patients treated14. CDC recommends follow up at 1-2 weeks (SpO2 and chest x-ray). Some patients have relapsed during corticosteroid tapering, and some have had persistent hypoxemia (SpO2 <95%) requiring home oxygen at discharge14.
ARDS has an incidence of 30–80 cases per 100,000 populations15. It is divided into three categories as per Berlin definition from 2012 according to severity of hypoxemia as mild (PaO2 /FiO2 200–300 mmHg), moderate (PaO2/FiO2 100–200 mmHg) and severe (PaO2/FiO2 < 100 mmHg) forms of ARDS.
Despite a much-improved understanding of ARDS pathophysiology, the efficacy of used therapeutic approaches is limited. In our case, poor compliance of the lungs despite the low requirement of FiO2 up to 50% was remarkable. For a set tidal volume of 5 ml/kg, his peak inspiratory pressure was reaching up and beyond 35 cm H2O. Thus we resort to ultra-protective lung ventilation with tidal volumes of 4 to 5 ml/kg as required to avoid barotrauma. Prone positioning was useful especially in the acute phase of severe ARDS, by enabling better ventilation/perfusion matching, more homogenous distribution of ventilation with reduction of Ventilator-induced lung injury and recruitment of dorsal regions16.
The use of neuromuscular blocking agents (NMBA) improves patient-ventilator synchrony and reduces oxygen consumption leading to improved survival17. However, when given alone with steroids, it can exacerbate weakness due to critical illness myopathy and polyneuropathy18.In our case, it could not be avoided as we had to balance the risk of ICU-acquired weakness with the potential benefit of neuromuscular blockers and systemic glucocorticoids in the severe lung injured patient.
Lee et al. highlighted various new outcomes that need to be studied in Pediatric Acute Respiratory Distress Syndrome (PARDS) like long term pulmonary function, risk of pulmonary hypertension, nutrition status and growth, PICU acquired weakness, neurocognitive development, functional status and Health-related quality of life (HRQOL)19. A cohort study conducted on 316 mechanically ventilated pediatric patients concluded that 23% developed new morbidities due to residual organ dysfunction, treatment complications etc20.
There have been numerous studies on long term outcomes in adult ARDS. One study with potential application to pediatrics illustrated that half of the patients had persistent functional disability 12 months after discharge21. The 6-minute walk test (6MWT) helps assess global physical function, i.e., lung and cardiac function and muscle strength. The mean distance walked in the 6MWT increased significantly over the first year when followed up at three months and 9-12 months after discharge22.
Our patient had significantly reduced spirometry parameters upon discharge from the PICU, which got almost normalized within three months post-discharge from the hospital.