اشتباهات شایع در بخش آی سی یو 3
Do not Insert, Change, or Remove A Central Line With the Patient Sitting Up
Aaron Bransky MD
Heidi Frankel MD
The insertion of central venous catheters is an extremely common procedure in the United States, accounting for more than 5 million procedures annually. There are many different complications that have been described. One of the more underrecognized and feared complications is a venous air embolism. Clinically, air embolism may present with acute chest pain, hypoxia, dyspnea, hypotension, visual changes, or convulsions.
The two most common times for air embolism to develop are upon placement or removal of a central venous catheter, including instances of intentional or inadvertent removal by the patient. Upon placement of a central venous catheter, proper care should be taken to prevent each lumen of the catheter from connecting with atmospheric air without a column of fluid within it. Furthermore, to increase central venous pressure, the catheter should be placed with the patient in a Trendelenburg position. Removal of a catheter should also be done with caution, particularly in a cachectic patient or if the catheter has been in place for a sustained time and a fibrous sheath has developed. The patient should be placed in a Trendelenburg position with his or her breath held. Upon removal of the catheter, an occlusive dressing should be placed immediately. The risk of death is related to both the volume of the air embolus and the rate at which it enters. In humans, the minimum injection rate and volume are 100 mL/sec and 300 to 500 mL, respectively.
The actual physiological mechanism that causes the hemodynamic instability from an air embolus is a right ventricular outlet obstruction caused by the slurry of churned air embolus with blood. Because gases rise, the patient should be placed in a position where the gas will exit the ventricle or prevent it from entering the ventricle. This is best accomplished by the reverse Trendelenburg position with the left side down. This places the right atrium in the least dependent position, causing air to ascend to this position. Once the patient is in this position, if the central venous catheter remains in place, an attempt can be made to aspirate the air, although this is rarely successful. Other proposed therapies include hyperbaric oxygen that addresses
the neurological disturbances that occur as a result of a patent foramen ovale (present in up to 30% of the population) or a shunt. Hyperbaric oxygen is successful if utilized early after recognition of neurological symptoms.
Orebaugh SL. Venous air embolism: clinical and experimental considerations. Crit Care Med 1992;20:1169â€“1177.
Pronovost PJ, Wu AW, Sexton JB. Acute decompensation after removing a central line: practical approaches to increasing safety in the intensive care unit. Ann Intern Med 2004;140:1025â€“1033.