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Year : 2017  |  Volume : 11  |  Issue : 2  |  Page : 252-254

“Anesthesia bubbles:” Demystifying the enigma!

Department of Anaesthesia and Intensive Care, Government Medical College and Hospital, Chandigarh, India

Correspondence Address:
Dheeraj Kapoor
1207, Sector 32 B, Chandigarh - 160 030
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/1658-354X.203054

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Date of Web Publication27-Mar-2017

How to cite this article:
Kapoor D, Dhal A, Singh J, Singh M. “Anesthesia bubbles:” Demystifying the enigma!. Saudi J Anaesth 2017;11:252-4

How to cite this URL:
Kapoor D, Dhal A, Singh J, Singh M. “Anesthesia bubbles:” Demystifying the enigma!. Saudi J Anaesth [serial online] 2017 [cited 2023 Mar 28];11:252-4. Available from:


“Anesthesia bubbles” is a colloquial term used often by surgeons though rarely described in literature.[1],[2],[3] It is defined as the presence of large and visible collection of gas bubbles in exposed venous channels during neck surgeries and attributes its expanded size to diffusion of dissolved nitrous oxide in blood.[1] It is presumed to be a benign entity, however, its exact etiology, clinical outcome, and ensuing management are still not clear.

We discuss a case where we observed “anesthesia bubbles” in surgically exposed jugular veins, in 37-year-old, American Society of Anesthesiologists Grade 2, male patient with diagnosis of squamous cell carcinoma of the tongue (right lateral border) and cervical lymphadenopathy, undergoing wide local excision and supraomohyoid neck dissection surgery. General anesthesia was instituted (induction: fentanyl [120 μg intravenous (IV)], propofol [120 mg IV]; muscle relaxation: vecuronium bromide [6 mg IV]; maintenance: 40:60 oxygen-nitrous oxide mixture and isoflurane [1%–2%]), and patient trachea was intubated with cuffed armored tube (8.0 internal diameter). Surgery was initiated with the patient in supine position with mild neck extension by the placement of blanket roll beneath the patient's shoulders.

During the surgical dissection of neck, surgeons noticed the train of air bubbles in the right external and internal jugular veins [Figure 1]. These bubbles were large, visible with no movement. Nitrous oxide was immediately stopped, and the patient was ventilated with 100% oxygen, headend was positioned down, and surgical field was flooded with saline and wet gauze pieces. No site of air entry was localized in exposed venous channels after performing “Valsalva” maneuver. Transthoracic echocardiography done and revealed no gross abnormality. Patient hemodynamic parameters were stable and therefore under strict monitoring, rest of surgery was allowed. Nearly 30 min after the aforesaid event, the visible bubbles disappeared spontaneously with stable hemodynamics. After completion of procedure, patient trachea was extubated, and he was kept in high dependency unit (HDU) for intensive monitoring of hemodynamic and neurological parameters. The rest of the postoperative course was unremarkable.
Figure 1: Black arrows indicating air in internal jugular vein

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There are few assumptions, which try to explain the possible cause of “anesthesia bubbles.” These bubbles maybe due to the air entrainment in the incised venous channels having subatmospheric pressure, hence creating a pressure gradient as classically seen in venous air embolism (VAE).[4] However, to create such potential pressure gradient, the surgical wound may require a sizeable height (more than 5 cm) above right atrium by making a head-up position as seen in certain neurosurgical and otolaryngological interventions.[5] In the present case, the position of the patient was supine and horizontal with deliberate mild extension of the neck to create acceptable surgical access. Apparently, the height created by this position generates a negligible pressure gradient hence reducing the likelihood of significant air entrainment. This minimal pressure gradient may also explain the static characteristics of the bubbles with negligible movement in either cephalad or caudad direction.

It has also been argued that peripheral IV lines maybe the potential source of “anesthesia bubbles.”[1] Entrainment of air is attributed due to the pressure gradient between air and venous blood by the insertion of IV cannula, allowing the ingress of air into the venous system.[5] Manifesting this entrained air in the jugular veins, air has to either float retrograde up in jugular system or tread through pulmonary and cerebral capillary beds as microscopic bubbles or directly through shunt bypassing the aforesaid capillary beds.[1] However, the above-mentioned mechanism does not decisively substantiate the appearance of such large bubbles in jugular veins in the present case and that too with no evidence of any clinically significant systemic manifestation.[1]

In head and neck surgery, there are certain factors, which cause hemodynamic variations (such as acute hypotension, cardiac arrhythmia, and ischemia), such as anesthetic drugs, stimulation of carotid baroreceptor by surgical manipulation, or associated comorbidities.[1] The occurrence of “anesthesia bubbles” seems benign but its disappearance may leads to similar hemodynamic variations and may further precipitate the development of fatal VAE and hence should be considered in differential diagnosis.[1]

Anesthesiologists should be aware of this rare clinical entity and should follow a diligent approach. Nitrous oxide should be stopped immediately to prevent its further expansion. These bubbles should be observed and mandate intensive monitoring of hemodynamics with advance sensitive monitoring devices such as transesophageal echocardiography, precordial Doppler, end-tidal nitrogen, and carbon dioxide analyzers. Surgeons maybe directed for fine-needle aspiration of grossly visible jugular air bubbles. Suspecting central VAE during the course requires immediate management, by prevention of further air entrainment, aggressive hemodynamic support, central venous catheter aspiration, and early institution of cardiopulmonary resuscitation.


We wish to thanks Dr Vaibhav Saini (Otolaryngologist), Assistant Professor of our institution, for their valuable inputs and contribution for drafting of this research paper.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Rice JH, Gonzalez RM. Large visible gas bubbles in the internal jugular vein: A common occurrence during supine radical neck surgery? J Clin Anesth 1992;4:21-4.  Back to cited text no. 1
Hickey C, Backman SB, Steinmetz O. Visible bubbles in the internal jugular vein during carotid endarterectomy. Can J Anaesth 1999;46:401.  Back to cited text no. 2
Anandaswamy TC, Thamanna PP, Rajappa GC, Chikkapillappa MA. Incidental detection of venous air embolism during modified radical neck dissection. Karnataka Anaesth J 2016;2:39.  Back to cited text no. 3
  [Full text]  
Hybels RL. Venous air embolism in head and neck surgery. Laryngoscope 1980;90(6 Pt 1):946-54.  Back to cited text no. 4
Sviri S, Woods WP, van Heerden PV. Air embolism – A case series and review. Crit Care Resusc 2004;6:271-6.  Back to cited text no. 5


  [Figure 1]


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