Pages: 1 2

Functional disorders and their morphological manifestations in mechanical asphyxia

As a rule, mechanical asphyxia occurs acutely. All its course from beginning to death fits in 6-8 minutes (the time for which killed the cerebral cortex). Despite the short duration of the period lifetime course of asphyxia in the body occur acute physiological processes proceeding in stages, which are reflected in the clinic and pathological manifestations that are discovered during the examination of the corpse.
In some cases the process of asphyxia starts with a reflex breath (20 to 30 C). If the mechanical obstruction to breathing not eliminated, then comes anoxia, during which it is possible to allocate 4 phases, passing one another without any interval.
Phase inspiratory apnea is characterized by the extension and strengthening of breath due to irritation of the respiratory centre accumulating in the blood carbon dioxide. In this phase, increased blood pressure, increases and increased activity of the heart. You may experience erratic movements of the limbs. The duration of this phase -40 to 60 C, after which it is replaced by phase expiratory dyspnea. Excessive levels of carbon dioxide causes severe stimulation of the respiratory and vasomotor centers. In this phase exhale prevails over the breath. Inspiratory and expiratory dyspnea should be considered as an adaptive response of the body to acute hypoxia. These reactions occur reflex due to strong irritation of chemoreceptors in the brain stem and aortic carotid zone changed (mainly due to hypercapnia - high content of carbon dioxide in the blood and other tissues) of blood gas composition. Experience short-lived convulsive movement of certain muscle groups. This may be involuntary selection of feces, urine, semen. Increased blood pressure, heart rate slows down. Visible mucous become cyanotic, sensitivity and reflexes are absent. In the late first and early second phase, i.e. through 40-60 seconds after the start of asphyxia, lost consciousness. Following this, the third phase - the relative peace or short-term breathing stops (about 1 minute), due pererastayut stray nerves and a decrease in excitability of the respiratory center because of the excessive accumulation in blood carbon dioxide. Arterial pressure decreases.
Short stops breathing is replaced by the last, fourth phase of the terminal breaths, manifested in the form of individual, irregular breathing movements within minutes 1-3-5
In this phase, there is a strong extinction of all reflexes, dilated pupils, muscle relaxation, a sharp drop in blood pressure. Develop severe seizures. After this comes persistent respiratory failure due to paralysis of the respiratory center. It should be noted that abnormal heart rhythm can be observed for some time (3-10 minutes).
This is a typical lifetime for acute mechanical asphyxia. In patients suffering from ischemic heart disease, death may occur already in the phase of breathlessness due to reflex cardiac arrest.
Listed sharp pathophysiological changes are reflected in the pathological manifestations detected when an external and internal examination of the corpse. These morphological phenomena are studied fairly fully and in detail for several decades ago. It was believed that they are specific to mechanical asphyxia, and why were named "common signs of asphyxia". Further research found that these features, which are based on sharp circulatory disorder, may not be considered as specific for mechanical asphyxia, because they characterize the death of the primary respiratory arrest, and in different combinations meet with the other types quickly coming death, not only asphyxia. However, they are of great diagnostic value and in combination with specific characteristics that are specific to each particular type of asphyxia, are the basis for forensic medical diagnosis asphyxia and its specific type.