tailieunhanh - Trauma Resuscitation - part 4

Khả năng thất bại nhiều cơ quan supervening tăng lên nếu hồi sức và sửa chữa sốc tuần hoàn không đầy đủ hoặc trì hoãn. Nguyên nhân của cú sốc Mặc dù có một số nguyên nhân gây sốc, | SHOCK 87 the commonest causes of late death after trauma. The likelihood of multiple organ failure supervening is increased if resuscitation and correction of circulatory shock is inadequate or delayed. Causes of shock Although there are a number of causes of shock after trauma there is usually a hypovolaemic component. This is also the most easily managed and should be identified and treated before it is attributed to other causes. Hypovolaemic shock In the trauma patient haemorrhage may be overt when its volume is often overestimated or occult and underestimated. Occult haemorrhage occurs into the cavities of the thorax abdomen and pelvis or in potential spaces for example the retroperitoneal space and muscles and tissues around long bone fractures. Intravascular volume is also lost as a result of leakage of plasma through damaged capillaries into the interstitial spaces accounting for up to 25 of the volume of tissue swelling following blunt trauma. The rate of venous return to the heart is dependent on the hydrostatic pressure gradient between the peripheral veins and right atrium of the heart Hypovolaemia tension pneumothorax or cardiac tamponade will reduce this gradient and venous return to the heart thereby decreasing cardiac output and arterial pressure. External compression on the thorax or abdomen may have a similar effect in obstructing venous return. In relatively young fit patients the compensatory mechanisms described earlier may minimize the effects on cardiac output and arterial pressure following acute haemorrhage up to l blood . approximately 20-25 total blood volume BOX BLOOD VOLUMES Adult 70 ml per kilogram ideal body weight approximately 5 l in 70 kg person Child 80 ml per kilogram ideal body weight see Box . Tolerance may be much less than this in the elderly and those with cardiovascular comorbidity. Cardiogenic shock In cardiogenic shock due to myocardial trauma and or ischaemia the compensatory sympathetic