Gas Embolism

N Engl J Med 2000; 342:2000-2002June 29, 2000

Article

To the Editor:

In their review, Muth and Shank (Feb. 17 issue)1 discussed the pathophysiology, diagnosis, and treatment of gas embolism, a potentially fatal complication of various medical and surgical procedures. Although we found the review to be valuable, we are concerned that one of the treatment recommendations runs counter to the consensus opinion. Specifically, in Table 2, the authors indicate that the proper positioning of a patient with venous gas embolism is in the “supine, flat” position. However, most authorities recommend that patients with suspected venous gas embolism be placed in a left lateral decubitus position with the head tilted downward (Trendelenburg's position).

Durant et al. demonstrated that dogs that were subjected in experiments to air emboli were more tolerant of air infusion, as indicated by measurement of hemodynamic variables, while lying on their left sides.2 Durant et al. observed that this position placed the right ventricular outflow tract in a position inferior to the right ventricular cavity, allowing the air bolus to migrate superiorly and removing the obstruction to blood flow. In addition, Trendelenburg's position prevents the gas embolism from occluding the outflow tract by placing the right ventricular cavity in a more superior position.3 These simple positional maneuvers should be performed in patients with a suspected venous gas embolism; they have been recommended by others who have written on the subject.3-5

Terrence D. Coulter, M.D.
Herbert P. Wiedemann, M.D.
Cleveland Clinic Foundation, Cleveland, OH 44195

5 References

1
Muth CM, Shank ES. Gas embolism. N Engl J Med 2000;342:476-482
Full Text | Web of Science | Medline

2
Durant TM, Long J, Oppenheimer MJ. Pulmonary (venous) air embolism. Am Heart J 1947;33:269-281
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3
Lambert MJ III. Air embolism in central venous catheterization: diagnosis, treatment, and prevention. South Med J 1982;75:1189-1191
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4
Orebaugh SL. Venous air embolism: clinical and experimental considerations. Crit Care Med 1992;20:1169-1177
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5
Coppa GF, Geuge TH, Hofstetter SR. Air embolism: a lethal but preventable complication of subclavian vein catheterization. JPEN J Parenter Enteral Nutr 1981;5:166-168
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To the Editor:

. . . Figure 2 of the article by Muth and Shank is a misleading representation of the appearance of an intraarterial gas bubble in vivo. Our work demonstrates that bubbles are distorted into a sausage shape.1 This difference in geometry in vivo means that the relations between bubble volume or surface area and ambient pressure shown for spherical bubbles in Figure 3 of the article do not apply. The altered shape of the bubble in vivo prolongs the absorption time, worsening the pathophysiologic consequences of an embolic event.2 We have also demonstrated that microvascular gas bubbles provoke local arteriolar vasoconstriction. The depiction of the vessel wall bulging out around a spherical bubble in Figure 2 thus substantially understates the surface area of endothelium in contact with the bubble. The spatial and temporal effects of microvascular gas embolism are considerably worse than described by Muth and Shank.

David M. Eckmann, Ph.D., M.D.
University of Pennsylvania, Philadelphia, PA 19104

Annette B. Branger, M.S.
Northwestern University, Evanston, IL 60208

Daniel P. Cavanagh, Ph.D.
Bucknell University, Lewisburg, PA 17837

2 References

1
Cavanagh DP, Eckmann DM. Interfacial mechanics of stationary bubbles in flows in inclined tubes. J Fluid Mech 1999;398:225-244
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2
Branger AB, Eckmann DM. Theoretical and experimental intravascular gas embolism absorption dynamics. J Appl Physiol 1999;87:1287-1295
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To the Editor:

In their excellent review of gas embolism, Muth and Shank did not refer to venous air embolism after the removal of a central venous catheter. The need to avoid air embolism during the insertion and manipulation of a central venous catheter is widely understood, but the risk associated with removal of the catheter is less widely known.1 In a recent hospital survey, Ely et al.2 found that 91 percent of 140 physicians placed patients in Trendelenburg's position when they were inserting a central venous catheter, but only 26 percent of the physicians knew that venous air embolism could occur after the removal of the catheter. Moreover, 14 percent removed catheters from patients who were placed in positions that could theoretically increase the incidence of this serious complication.

We have treated four patients with serious complications of gas embolism. Two cases occurred after the removal of a central venous catheter, and two occurred because of a delay in seeking care after the accidental removal of a central venous catheter.

Fibrin tracts consistently form around catheters, sometimes within 24 hours, creating a potential for portal venous air entry after the removal of a catheter3 — even several minutes after the removal of the catheter.4 Therefore, central venous catheters should be removed while the patient is either supine or in Trendelenburg's position, and the insertion site must immediately be covered with a sterile gauze, with firm manual pressure maintained until hemostasis is achieved. The insertion site must then be covered with an air-occlusive dressing. The dressing should remain in place for 24 to 72 hours.1 It is also important to remember that urgent care is required to prevent gas embolism after the accidental removal of a central venous catheter.

Carlos Chamorro, M.D.
Miguel A. Romera, M.D.
Cándido Pardo, M.D.
Clínica Puerta de Hierro, Madrid 28035, Spain

4 References

1
Mennim P, Coyle CF, Taylor JD. Venous air embolism associated with removal of central venous catheter. BMJ 1992;305:171-172
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2
Ely EW, Hite RD, Baker AM, Johnson MM, Bowton DL, Haponik EF. Venous air embolism from central venous catheterization: a need for increased physician awareness. Crit Care Med 1999;27:2113-2117
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3
Hoshal VL Jr, Ause RG, Hoskins PA. Fibrin sleeve formation on indwelling subclavian central venous catheters. Arch Surg 1971;102:353-358
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4
Turnage WS, Harper JV. Venous air embolism occurring after removal of a central venous catheter. Anesth Analg 1991;72:559-560
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Author/Editor Response

The authors reply:

To the Editor: Chamorro and colleagues point out the need for vigilance during the removal of a central venous catheter. We included this potential mechanism in Table 1 of our article: “entry of air through disconnected intravascular catheter, inadvertent infusion of air through intravascular catheter.” This is an important mechanism of gas embolism and deserves to be emphasized.

Eckmann and colleagues correctly suggest that an intraarterial gas bubble in vivo is more sausage-shaped than spherical — a point that helps explain why a bubble induces damage through complex interactions with the blood vessel's endothelium and the surrounding tissues. Our Figure 2 was designed to summarize the complex pathophysiology in a simple diagram.

Coulter and Wiedemann believe the left lateral decubitus position with the head tilted downward is the preferred position for the treatment of venous gas embolism, citing a study that was performed more than 50 years ago.1 The results of that study suggested that dogs that received massive infusions of air were more likely to survive if they were in the left lateral decubitus position. More recent studies2,3 indicate that hemodynamic responses are not improved by the use of alternative positions instead of a flat, supine position. These studies did demonstrate that intracardiac air relocates to more nondependent regions. If a transvenous catheter is present in the right side of the heart, placing the patient in the left lateral decubitus position before attempting to withdraw the air may have merits, as we mentioned in Table 2.

For most patients with venous gas emboli, placing them in the supine position affords physicians a better opportunity to administer supportive therapy, including ventilatory support and oxygen, to establish access for catecholamine delivery, and to perform cardiopulmonary resuscitation. Thus, since there are no demonstrated hemodynamic improvements associated with the use of the left lateral decubitus or head-down position, we believe that the supine position is the best choice.

Finally, the legend for Figure 2 should have read, “Sodium and water enter the neurons, and cytotoxic edema develops,” not “Sodium and water enter the vessel . . . ,” as printed.

Claus Martin Muth, M.D.
Universitätskliniker des Saarlandes, 66424 Hamburg/Saar, Germany

Erik S. Shank, M.D.
Massachusetts General Hospital, Boston, MA 02114

3 References

1
Durant TM, Long J, Oppenheimer MJ. Pulmonary (venous) air embolism. Am Heart J 1947;33:269-281
CrossRef | Web of Science | Medline

2
Mehlhorn U, Burke EJ, Butler BD, et al. Body position does not affect the hemodynamic response to venous air embolism in dogs. Anesth Analg 1994;79:734-739
CrossRef | Web of Science | Medline

3
Geissler HJ, Allen SJ, Mehlhorn U, Davis KL, Morris WP, Butler BD. Effect of body repositioning after venous air embolism: an echocardiographic study. Anesthesiology 1997;86:710-717
CrossRef | Web of Science | Medline

Citing Articles (3)

Citing Articles

1
Doug T. Valassis, Robert E. Dodde, Brijesh Esphuniyani, J. Brian Fowlkes, Joseph L. Bull. (2011) Microbubble transport through a bifurcating vessel network with pulsatile flow. Biomedical Microdevices
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2
S.S. Hare, A. Gupta, A.T.C. Goncalves, C.A. Souza, F. Matzinger, J.M. Seely. (2011) Systemic arterial air embolism after percutaneous lung biopsy. Clinical Radiology 66:7, 589-596
CrossRef
3
Andres J. Calderon, Brijesh Eshpuniyani, J. Brian Fowlkes, Joseph L. Bull. (2010) A boundary element model of the transport of a semi-infinite bubble through a microvessel bifurcation. Physics of Fluids 22:6, 061902
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