EXTERNAL MASSAGE In patients with cardiac arrest due to chest trauma, external cardiac massage is generally of no value and is in fact likely to be harmful. Since the trauma patient suffering cardiac arrest is generally hypovolemic, external massage is usually ineffective and may actually cause significant additional injury to the heart, liver, lungs, or great vessels. In addition, forced ventilation and external cardiac compression may result in air emboli in the coronary arteries.
INTERNAL (OPEN) MASSAGE Resuscitative thoracotomy can be helpful in selected patients, i.e. those with signs of life within 5 min of arrival in the ED and penetrating wounds of the chest. However, a resuscitative thoracotomy is seldom of benefit in (1) patients with blunt trauma, (2) patients with penetrating abdominal or head injuries, and (3) patients "dead at the scene."
Open cardiac massage is usually performed through an anterolateral incision in the fifth intercostal space on the side of the injury. The pericardium is opened vertically 1 to 2 cm anterior to the phrenic nerve. The thoracic incision allows direct inspection of the heart, control of bleeding sites in the chest, and complete evacuation of any pericardial tamponade or hemopneumothorax. In addition, a left thoracotomy allows the physician to compress or clamp the descending thoracic aorta.
Since about 60 percent of the cardiac output normally goes to the tissues below the diaphragm, clamping of the descending thoracic aorta can increase coronary and carotid blood flow almost threefold. If the arterial systolic blood pressure does not rise to 90 mmHg within 5 to 10 min of aortic cross-clamping, further resuscitation will probably be of no avail. On the other hand, if the proximal aortic pressure rises above 160 to 180 mmHg in a previously normotensive individual, it can damage the brain and/or left ventricle.
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.