LETTER TO THE EDITOR
|Year : 2021 | Volume
| Issue : 1 | Page : 85-86
Venous air embolism during endoscopic transsphenoidal resection of pituitary tumor: Need to be cautious
Shalvi Mahajan, Sanjay Kumar, Hemant Bhagat, Rajeev Chauhan
Department of Anaesthesia and Intensive Care, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
|Date of Submission||27-Sep-2019|
|Date of Decision||03-Dec-2019|
|Date of Acceptance||22-Aug-2020|
|Date of Web Publication||25-Jun-2021|
Dr. Sanjay Kumar
Department of Anaesthesia and Intensive Care, Sector-12, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh.
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Mahajan S, Kumar S, Bhagat H, Chauhan R. Venous air embolism during endoscopic transsphenoidal resection of pituitary tumor: Need to be cautious. J Pediatr Neurosci 2021;16:85-6
Pituitary tumor constitutes 10%–15% of all neuro-oncological intracranial tumors. Endoscopic neuro-navigation-guided approach for pituitary surgery is in vogue. Here we report a case of 8-year-old female child who presented with atraumatic bilateral painless progressive vision loss. She was diagnosed with space occupying lesion in sellar-suprasellar region and endoscopic trans-nasal transsphenoidal resection of pituitary tumor was planned. Pre-anesthetic check-up was done. Preoperatively, thyroxine 50 mcgs/day and hydrocortisone 2.5mg once a day were started. Informed consent was taken. Standard general anesthesia technique was instituted. Induction of anesthesia was achieved using intravenous (i.v.) propofol 40mg; muscle relaxation was achieved using vecuronium 2.5mg. For intraoperative analgesia, morphine 3mg i.v. was administered. Airway was secured using 5.5 mm cuffed endotracheal tube. Left radial artery was cannulated for continuous blood pressure monitoring after induction of anesthesia. Maintenance of anesthesia was achieved using oxygen/sevoflurane and nitrous oxide (1.2–1.5 MAC). Intraoperative monitoring includes electrocardiogram, pulse oximetry, noninvasive and blood pressure, end-tidal concentration of carbon-dioxide (Etco2) using capnography, and inhaled anesthetic agents. Throughout intraoperative period vitals were stable. Toward the end of procedure, when surgeon was placing fat graft along with fascial graft for the final dural defect packing, Etco2 levels fell from 33 to 23 mm Hg, followed immediately by a decrease in arterial blood pressure to 71/40 mm Hg and a slight increase in heart rate without change in oxygen saturation [Figure 1]. Immediately surgeon was informed about the suspicion of venous air embolism (VAE). Simultaneously, fraction of inspired oxygen was increased to 100%, nitrous oxide was switched off and i.v. fluids were rushed. Arterial blood gas analysis (at the time of event) revealed a pH of 7.24, PaO2 of 168 mmHg, and PaCO2 of 45 mm Hg [Figure 1]. Central venous line was not inserted so air aspiration could not possible. Nearly 15min after aforesaid event, vitals including Etco2 reach pre-event status and blood gases were also within normal range. After the conclusion of surgery, it was decided to extubate patient following reversal of neuromuscular blockade. Later, patient was shifted to neurosurgical intensive care unit where rest of her course was uneventful.
|Figure 1: (Left- Monitor depicts fall in Etco2 and Right - Arterial blood gas reveal High PaCO2)|
Click here to view
None of the neurosurgical procedure is immune to the occurrence of VAE. The inherent risk factors for VAE in neurosurgery are head-up position above heart level, hypovolemia, pediatric age group (<9 years), and presence of excessive venous channels in course of the surgical pathway. In our case, head elevation (20°) required for surgical positioning, even 5cm of gradient between right atrium and surgical site is associated with VAE. Also, nonpneumatized sphenoid bone was also present. Non-pneumatized sphenoid bone contains venous channels which further predisposes to VAE. Fall in Etco2 corresponded to fat graft placement by neurosurgeon during dural defect closure so it could be possible that air has been pushed into inter-cavernous venous connections sinus during fat graft placement in the presence of inadequately sealed sub-nasal vessels. These inter-cavernous venous connections are non-collapsible venous connections within the sella and in the sphenoid. There is another possibility of some micro-emboli entering into the venous channels from the fat graft which resulted in fall in Etco2. For diagnosis of VAE, capnography is the most readily available diagnostic modality with moderate sensitivity and specificity. A sudden drop in Etco2 is an earliest indicator of VAE.
Search into literature, we found only two case reports which highlighted occurrence of VAE during pituitary surgery. First report was published in 1978 where Doppler ultrasound cardiac monitoring detected VAE in 3 out 31 consecutive transsphenoidal pituitary surgery cases where one case was symptomatic and other two cases had no change in vital signs. Arora et al. reported the occurrence of non-cardiogenic pulmonary edema following tracheal extubation, need for reintubation, postoperative mechanical ventilation, and supportive treatment following two recurrent episodes of VAE during TSS pituitary surgery.
To conclude, VAE is an unusual dreaded complication during endoscopic transsphenoidal tumor resection. Thus, diligent intraoperative monitoring to detect VAE should be done even during the late phases of pituitary surgery.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Newfield P, Albin MS, Chestnut JS, Maroon J. Air embolism during trans-sphenoidal pituitary operations. Neurosurgery1978;2:39-42.
Arora R, Chablani D, Rath GP, Prabhakar H. Pulmonary oedema following venous air embolism during transsphenoidal pituitary surgery. Acta Neurochir (Wien) 2007;149:1177-8.