Pulmonary and serum surfactant phospholipids and serum catecholamines in strangulation. An experimental study on rats

Elevations of phospholipid and catecholamine concentrations in the blood are regarded as the vital reactions in asphyxial deaths, which leave few or no morphological signs in the body. These vital reactions were tested here, under strict experimental conditions, employing rapid asphyxia. Rats anaesthetized with barbiturate were strangled with a rope 2 mm thick tightened with a force of 29.4 N (3 kp). The main surfactant components, phosphatidyl choline and phosphatidyl ethanol amine, were measured in serum and lung samples, and catecholamines in the serum. The lungs were also investigated histologically. The serum phospholipid concentration in the strangulated rats was 1.36 +/- 0.32 g/l, versus 1.04 +/- 0.17 g/l in the controls (barbiturate intoxication), P < 0.001, but no change in their content was observed in the lungs (26.21 +/- 4.04 mg/g vs. 25.15 +/- 3.64 mg/g dry weight). Histologically, focal emphysema and tiny haemorrhages were seen in the lungs of both groups with similar frequency. Mean serum noradrenaline (NA) and adrenaline (A) concentrations were significantly higher in the strangulation group (NA = 5.4 +/- 2.6 ng/ml vs. 2.8 +/- 0.1 ng/ml, P < 0.001 and A = 6.0 +/- 3.4 ng/ml vs. 3.8 +/- 3.0 ng/ml, P < 0.05). The results support the notion that phospholipid and catecholamine concentrations are increased in the blood upon suffocation and could thus be taken as indicators of hypoxia. Further investigations into postmortem phospholipid change or stability are needed. There are reports that phospholipid concentration remain quite stable for two days post mortem, whereas catecholamine concentrations tend to rise quite soon after death.