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roentgenograms of the month Sudden Apnea Following Attempted Central Line Placement* Keith M. Clance, M.D.; and Frederick L. Glauser; M.D.
(Chm 1991; 100:505-06)
man presented with the acute onset A of75-year-old lumbosacral pain that radiated circumferentially to his abdomen. There was no history of trauma, fevers, chills, or renal calculi. His medical history was significant for an abdominal aortic aneurysm measuring 4 x 6 cm since 1986, a right upper lobectomy in 1980 for localized squamous cell carcinoma, and chronic obstructive pulmonary disease. Blood pressures were equal in each arm. The abdomen was soft, diffusely tender, with a 10-cm pulsatile mass to the left of midline. There was no rebound tenderness or abnormal bowel sound. Stool was hemoccult negative. Distal pulses were decreased symmetrically. Findings from the remainder of the physical examination were unremarkable. Results of laboratory studies were all within normal limits. A chest roentgenogram revealed right upper lobe scarring and surgical clips, consistent with a previous upper lobectomy, as well as changes consistent with chronic obstructive pulmonary disease. A lumbosacral spine series revealed normal bone structures and a 10-cm abdominal aortic aneurysm outlined by luminal calci6cations. In preparation for an abdominal computed tomographic (CI') scan, followed by surgical repair, attempts were made to establish central venous access via the right internal jugular approach. After placing the patient in the Trendelenburg position, the vein was easily cannulated; however, resistance was met while trying to advance the guidewire. The patient became *From the Pulmonary/Critical Care Division, Medical College of Virginia/Maguire VA Medical Center, Richmond, Va.
apneic and developed electromechanical dissociation followed by asystole. He was intubated, and cardiopulmonary rescusitation was begun. An 18-gauge needle was placed into the second intercostal space in the event these cardiac disturbances were secondary to a tension pneumothorax, and an emergency chest roentgenogram was obtained (Fig 1).
FIGURE
1
CHEST I 100 I 2 I AUGUST, 1991
505
Diagnosis: '\enous air embolus
Venous air embolism is an uncommon but serious complication of central venous catheterization. Although usually associated with disruption of catheter connections, it can also occur during the insertion itself, since negative intrathoracic pressure is transmitted to the large central veins during normal inspiration.1·2 Therefore, care must be taken during insertion and removal of guidewires, and during manipulations of catheter-tubing connections, to prevent communication between the atmosphere and central veins. Clinical manifestations of venous air embolism are nonspecific and may mimic primary cardiopulmonary events. Patients usually develop respiratory distress ranging from tachypnea to apnea. Significant hypoxemia is common, and may be due to V/Q mismatching, 3 edema and atelectasis, 4 and opening of intrapulmonary arteriovenous (AV) shunts. 5 Hypotension with subsequent cardiovascular collapse is not unusual and is secondary to pulmonary vasculature and right ventricular outHow tract obstruction. 6 •7 Infrequently, a "millwheel" murmur attributed to frothing of blood and air at the pulmonary valve may be heard. 8 Chest roentgenograms may verify the presence of a venous air embolus, but should not be depended on in emergent situations. Findings include air in the main pulmonary artery or ventricles, focal upper lung zone oligemia, central pulmonary artery dilatation, and air in the systemic venous or arterial circulation. 9 In our patient (Fig 2 and 3), large amounts of air can be seen in the axillary and jugular venous systems. It is unusual to see this degree of accumulation of venous air without concomitant intracardiac or pulmonary artery air. When air emboli are suspected, the patient should be placed in the left lateral decubitus position to redistribute air to the cardiac apex above the right ventricular outHow tract, reestablishing pulmonary blood How. 10 The administration of 100 percent oxygen may increase the rate of diffusion of nitrogen from the pulmonary circulation into the alveolus, thus decreasing the time for reabsorption of the air. 11 The use of central venous and pulmonary artery catheters for aspiration of air from the right ventricular and pulmonary circulations remains controversial. 7 Prevention of air emboli is the primary goal. Before attemptins-central venous catheterization, the patient should be placed in the Trendelenburg position, and an adequate intravascular volume status should be established or maintained. During the procedure, great care should be taken to prevent exposure of the open needle and catheter hub to the atmosphere while passing the guidewire and connecting the intravenous (IV) tubing. 506
.F ICUl\E
2
FlCURE
3
REFERENCES
1 Peters JL, Armstrong R. Air embolism occurring as a complication of central venous catheterization. Ann Surg 1974; 179: 266-68
2 Kashuk JL, Penn I. Air embolism after central venous catheterization. Surg Gynecol Obstet 1984; 159:249-52 3 Hlastala M, llobertson T, Ross B. Gas exchange abnormalities produced by venous gas emboli. Respir Physiol 1979; 36:1-17 4 Ohkuda K, Nakahara K, Binder A, Staub N. Venous air emboli in sheep: reversible increase in lung microvascular permeability. J Appl Physiol 1981; 51:887-94 5 Berglund E, Josephson S, Ovenfors CO. Pulmonary air embolism: physiologic aspects. Progr Respir Res 1970; 5:259-63 6 Oppenheimer MJ, Durant TM, Lynch P. Body position in relation to venous air embolism, and the associated cardiovascular-respiratory changes. Am J Med Sci 19.53; 225:362-73 7 Munson ES, Paul WL, Perry JC, dePadua CB, Rhoton AL. Early detection of venous air embolism using a Swan-Ganz catheter. Anesthesiology 1975; 42:223-26 8 Brechner V. Bethune R. Recent advances in monitoring pulmonary air embolism. Anesth Analg 1971; 50:255-61 9 Kizer KW, Goodman PC. Radiographic manifestations of venous air embolism. Radiology 1982; 144:35-9 10 Durant TM, Oppenheimer MJ, Lynch PR, Ascanio GA, Webber D . Body position in relation to venous air embolism: a roentgenologic study. Am J Med Sci 1954; 227:509-20 11 Steffey EP, Gauger GE, Eger EI II. Cardiovascular effects of venous air embolus during air and oxygen breathing. Anesth Analg 1974; 53:599-003 Roentgenogram of the Month (Clance, Glauser)