Pulmonary function test findings in patients with acute inhalation injury caused by smoke bombs

Abstract

Background: This study aimed to determine the effects of smoke bomb-induced acute inhalation injury on pulmonary function at different stages of lung injury.

Methods: We performed pulmonary function tests (PFTs) in 15 patients with acute inhalation injury from days 3 to 180 after smoke inhalation. We measured the trace element zinc in whole blood on days 4 and 17, and correlations of zinc levels with PFTs were performed.

Results: In the acute stage of lung injury (day 3), 3 of 11 patients with mild symptoms had normal pulmonary function and 8 patients with restrictive ventilatory dysfunction and reduced diffusing capacity. Some patients also had mild obstructive ventilatory dysfunction (5 patients) and a decline in small airway function (6 patients). For patients with severe symptoms, PFT results showed moderate to severe restrictive ventilatory dysfunction and reduced diffusing capacity. PaCO₂ was significantly higher (P=0.047) in patients with reduced small airway function compared with those with normal small airway function. Whole blood zinc levels in the convalescence stage (day 17) were significantly lower than those in the acute stage (day 4). Zinc in the acute stage was negatively correlated with D_LCO/V_A on days 3, 10, and 46 (r=-0.633, -0.676, and -0.675 respectively, P<0.05).

Conclusions: Smoke inhalation injury mainly causes restrictive ventilatory dysfunction and reduced diffusing capacity, and causes mild obstructive ventilatory dysfunction and small airway function decline in some patients. Zinc is negatively correlated with DLCO/VA. Zinc levels may be able to predict prognosis and indicate the degree of lung injury.

Keywords: Zinc chloride; pulmonary function test; smoke inhalation injury.

Figure 1

PFT Changes on days 3, 6, 10, and 46 after smoke inhalation of patients with mild symptoms (patients 1 to 11). PFT results showed that patients mainly had restrictive ventilatory dysfunction and reduced diffusing capacity in the acute stage of smoke inhalation. Thereafter, the PFT results of all of the patients progressively improved (P<0.05). On day 46, one patient had mild reduced diffusing capacity. Data are presented as the percentage of the predicted value (d 3: n=11, d 6: n=11, d 10: n=10, d 46: n=8).

Figure 2

PFT Changes on days 3 to 180 after smoke inhalation of patients with severe symptoms (patients A and B). On day 3, the patients had moderate to severe restrictive ventilatory dysfunction and reduced diffusing capacity. Thereafter, the PFT results progressively improved. On the 140th day of follow-up, PFT results returned to normal. Data are presented as the percentage of the predicted value.

Figure 3

Zinc levels in the acute stage (day 4) and the convalescence stage (day 17) of four critically ill patients. In 4 patients who had zinc levels measured in the acute and convalescence stages, zinc levels in the convalescence stage were significantly lower than those in the acute stag (P=0.032, n=4).

Figure 4

Scatterplot of zinc levels in the acute stage (day 4) and DLCO/VA on days 3, 6, 10, and 46. Zinc (day 4) levels were negatively correlated with D_LCO/V_A on days 3, 10, and 46, but there was no significant correlation on day 6 (d 3: n=12; d 6: n=12; d 10: n=10; d 46: n=11).