Effects of tonicities of saline solutions on pulmonary injury in drowning

We studied the degree of pulmonary and hemodynamic compromise induced by six saline solutions of varying tonicities (0%, 0.225%, 0.45%, 0.9%, 2%, and 3%) instilled down the trachea. We also attempted to resuscitate the dogs after a simulated wet drowning in each of the solutions, with and without chlorine. A control study with similar degree of anoxia but no fluid in the lungs was also performed. For the pulmonary variables of alveolar-arterial oxygen pressure difference, intrapulmonary shunt fraction, and PaO2/fraction of inspired oxygen, the 0.225% NaCl solution was significantly (p less than .001) less injurious to the lungs, especially compared with sterile water. The 0.225% and 0.45% NaCl solutions were the least disruptive to pulmonary function; the pulmonary injury they produced was similar to injury in the control dogs. Chlorine in the solution at one to two parts per million did not influence the data. The 0.9% (isotonic, normal saline), 2%, and 3% NaCl drowning solutions showed little difference from one another in terms of pulmonary injury. They were significantly (p less than .05) better than sterile water and significantly (p less than .05) worse than the 0.225% and 0.45% NaCl solutions. Sterile water, whether chlorinated or not, was the most injurious to the lungs. The hemodynamic effects of the drowning solutions were explainable solely by the effects of anoxia.