Leaving vascular lines in place is essential for the investigation of iatrogenic injuries (165). Multiple puncture sites are evidence of repeated attempts to insert a line (Fig. 37; ref. 166). The subclavian vein approach is the most frequently used approach for central venous and Swan-Ganz catheters. The purpose of central venous lines is to measure central venous pressure, allow rapid administration of fluid, circumvent the use of inadequate peripheral veins, allow prolonged fluid and parenteral administration, and guide placement of transvenous pacemakers and Swan-Ganz catheters (167). A subcla-vian line can also be used for hemodialysis, particularly for a patient who needs urgent
Fig. 37. Postmortem radiograph—pneumothorax. Repeated subclavian punctures during introduction of central venous line.
treatment (168,169). A Swan-Ganz catheter measures pulmonary intravascular pressure, which reflects cardiac function. A chest radiograph identifies line placement (167).
12.1.1. Complications Resulting in Death
• Air embolism (see Chapter 5, Subheading 14.8.)
° Air embolism is a risk when central lines are inserted in the neck, thoracic and neurosurgical procedures are performed, or pneumothorax occurs (170-173). Lines are inserted with the patient horizontal or in a head-down tilt position (170-172,174). Estimates of the quantity of air sufficient to cause death from venous air embolism vary from 10 to 480 mL (171,175). Large volumes are tolerated, if introduced slowly into the circulation (176). Air in the right ventricle obstructs the flow of blood to the lungs, resulting in cardiac failure (173). Air can be introduced during the insertion of the line or following its disconnection (170). Air in the venous circulation can reach the systemic circulation by either interatrial/interventricular shunts or through the transpulmonary capillary bed (173,174,177).
° Postmortem external features of air embolism (173,178):
■ Cyanosis of face and neck.
■ Blood-stained fluid oozing from nose and mouth because of increased venous pressure.
■ Blisters of eyelids.
■ Protrusion of tongue.
■ Palpable subcutaneous emphysema.
■ Generalized cutaneous petechiae.
° Internal features of air embolism include:
■ Aspiration of air from right side of heart (Fig. 38).
■ Air can be present in the left ventricle.
■ Air bubbles apparent in blood vessels (e.g., coronary veins).
■ Microscopic examination of the lungs may reveal clear intravascular spaces surrounded by leukocytes and platelets (179).
• Perforation is a common cause of death (172).
° Hydrothorax (hemodialysis), hydropericardium, hydromediastinum, chylothorax, hemothorax (penetration of heart or major vein), pneumothorax (subclavian puncture; see Fig. 37; and refs. 165, 167, 168, 170, 171, and 180-184).
■ Left-sided central vein approach is associated with damage to the thoracic duct (172).
■ The vascular line can penetrate a major vein, the heart, or a pulmonary artery branch, leading to leakage of fluid and blood into the mediastinal, pleural, or pericardial cavities (Fig. 39; refs. 167, 168, 170, 171, and 183); a major neck artery may be inadvertently punctured when a line is introduced (Fig. 40).
■ Pneumothorax is the most common complication because of the proximity of the lung apex to the subclavian vein (Fig. 37; ref. 167).
° Retention of catheter fragment (167,170,180).
■ Most common cause is shearing of the tubing by the sharp beveled needle (iatro-genic or patient-caused [170,180]).
■ Can lead to myocardial perforation, pulmonary embolism. and thrombosis with infarction.
° Infection/sepsis (172,180).
° Intracardiac placement of catheter irritating heart (167).
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