|Year : 2014 | Volume
| Issue : 3 | Page : 351-354
Perioperative management and complications in patients with obstructive sleep apnea undergoing transsphenoidal surgery: Our institutional experience
Eiman Rahimi, Ramamani Mariappan, Suresh Tharmaradinam, Pirjo Manninen, Lashmi Venkatraghavan
Department of Anesthesia, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, Ontario, Canada
|Date of Web Publication||22-Jul-2014|
Department of Anesthesia, Toronto Western Hospital, University Health Network, University of Toronto, 399 Bathurst Street, Toronto, Ontario, M5T 2S8
Source of Support: None, Conflict of Interest: None
Background and Aims: Patients with endocrine diseases such as acromegaly and Cushing's disease have a high prevalence of obstructive sleep apnea (OSA). There is controversy regarding the use of continuous positive airway pressure (CPAP) following transsphenoidal surgery. The aim of this study was to compare the perioperative management and complications, in patients with or without OSA undergoing transsphenoidal surgery.
Materials and Methods: After Research Ethics Board approval, we retrospectively reviewed the charts of all patients who underwent transsphenoidal surgery in our institution from 2006 to 2011. Information collected included patients' demographics, pathology of lesion, history of OSA, anesthetic and perioperative management and incidence of perioperative complications. Patients with sleep study proven OSA were compared with a control group, matched for age, sex and pathology of patients without OSA. Statistical analysis was performed using t-test and Chi-square test and the P < 0.05 was considered to be significant.
Results: Out of a total 469 patients undergoing transsphenoidal surgery, 105 patients were found to be at risk for OSA by a positive STOP-BANG scoring assessment. Preoperative sleep study testing was positive for OSA in 38 patients. Post-operative hypoxemia (SpO 2 < 90) occurred in 10 (26%) patients with OSA and was treated with high-flow oxygen through face mask (n = 7) and by CPAP mask (n = 3). In the OSA-negative group, 2 patients had hypoxemia and were treated with low-flow oxygen using face mask. There were no differences between the groups with respect to post-operative opioid use, destination, hospital stay or other complications.
Conclusions: Post-operative hypoxemia in patients with OSA following transsphenoidal surgery can be treated in most but not all patients with high flow oxygen using the face mask. We were able to safely use CPAP in a very small number of patients but caution is needed to prevent complications. Further prospective studies are needed to determine the safe use of CPAP in patients after transsphenoidal surgery.
Keywords: Continuous positive airway pressure, obstructive sleep apnea, transsphenoidal surgery
|How to cite this article:|
Rahimi E, Mariappan R, Tharmaradinam S, Manninen P, Venkatraghavan L. Perioperative management and complications in patients with obstructive sleep apnea undergoing transsphenoidal surgery: Our institutional experience. J Anaesthesiol Clin Pharmacol 2014;30:351-4
|How to cite this URL:|
Rahimi E, Mariappan R, Tharmaradinam S, Manninen P, Venkatraghavan L. Perioperative management and complications in patients with obstructive sleep apnea undergoing transsphenoidal surgery: Our institutional experience. J Anaesthesiol Clin Pharmacol [serial online] 2014 [cited 2018 Aug 18];30:351-4. Available from: http://www.joacp.org/text.asp?2014/30/3/351/137266
| Introduction|| |
Obstructive sleep apnea (OSA) is a common sleep related breathing disorder with prevalence between 2 and 25% in the general population.  The incidence of OSA in patients with pituitary disease has been reported to be 60-80% in patients with acromegaly and 18-32% with Cushing's disease. ,, The main surgical approach for pituitary surgery is transsphenoidal surgery. There is an increased incidence of perioperative complications among patients with OSA undergoing surgery under general anesthesia.  The American Society of Anesthesiologist practice guidelines for the perioperative management of patients with OSA recommends, the use of continuous positive airway pressure (CPAP) or non-invasive positive pressure ventilation with or without supplemental oxygen during the post-operative period in patients who were using these modalities pre-operatively, unless contraindicated by the surgical procedure.  The application of CPAP has generally been thought to be contraindicated after transsphenoidal surgery.  Complications from the use of CPAP include pneumocephalus especially in the presence of a cerebrospinal fluid (CSF) leak. , Currently, there are no relevant guidelines or consensus existing for the management of OSA in patients undergoing transsphenoidal surgery.  The aim of this study was to compare the perioperative management and complications, in patients with or without OSA undergoing transsphenoidal surgery in our institution.
| Materials and Methods|| |
After getting the approval from institutional research ethics board, we retrospectively reviewed the charts of all patients who underwent transsphenoidal surgery in our institution from June 2006 to May 2011. The charts were retrieved from the institutional electronic patient record system. Data was collected from the patients' anesthesia, postoperative anesthesia care unit (PACU), neurocritical care unit, intensive care unit (ICU), respiratory therapist and other health care records. Where possible we retrieved the pre-operative assessment data from clinical anesthesia information system.
The outcome measures collected and analyzed include patient demographics, diagnosis, STOP-BANG score,  sleep-study history, the perioperative course including all complications and the post-operative management of OSA, when present. Postoperative desaturation was defined as an oxygen saturation (SaO 2 ) <90%, that is sustained for at least 10 min and which required treatment. We placed the data onto the data sheets with the same wordings as it was in the chart, thereby giving us freedom to categorize data.
Patients were categorized based on the underlying pathology into acromegaly, Cushing's disease, prolactinoma and others. Patients at risk for OSA were identified by a positive STOP-BANG score of >4. From this group, we identified those patients who had positive sleep study preoperatively. These patients were considered as OSA positive group. We then identified a control group (OSA negative) consisting of patients with either a negative sleep study result from the at risk group or with a negative STOP-BANG score. The control group was matched for age, sex and pathology to the OSA positive patients. The two groups were compared for the incidence of perioperative complications. Statistical analysis was done using t-test and Chi-square test as appropriate. P < 0.05 was considered as significant. All values expressed as mean ± standard deviation (SD).
| Results|| |
We identified 469 patients who had transsphenoidal surgery (male:female, 227:242) with an age range from 19-89 years and a mean (±SD) age of 51 ± 16 years. Among these, 358 patients had pituitary pathology consisting of acromegaly (53), Cushing's disease (54), prolactinomas (41), craniopharyngioma (34), non-secretory macroadenoma (170) and other pituitary lesions (6). The transsphenoidal approach was used for excision of skull base pathology in 111 patients.
With the use of the STOP-BANG scoring scale, 105 (22%) patients were identified as high risk for OSA. Of these, 53 (50%) had been tested pre-operatively for OSA and 38 (38/53, 72%) were found to be sleep test positive. The median STOP-BANG score was 4, mean ± SD of 4.1 ± 1.1. These 38 patients became the OSA positive group. A control group of 38 OSA negative patients, matched for age, sex and pathology were selected. Their median STOP-BANG score was 2, mean ± SD of 2.3 ± 1.3. The distribution of the patients according to pathology in both groups is shown in [Table 1]. Of the patients with OSA 23 (61%) were using CPAP for OSA pre-operatively.
Demographics and anesthesia management are shown in [Table 2]. Overall, OSA patients had higher body mass index and higher incidence of hypertension and diabetes. The incidence of difficult mask ventilation was higher in patients with OSA when compared to those without OSA. But, there was no difference in the incidence of difficult intubation between the two groups. Intraoperative hypertension and hypotension requiring treatment occurred more frequently in the OSA group. Patients with OSA also had lower overall intraoperative PaO 2 values and higher PaCO 2 values. During surgery, only one patient had a brief period of hypoxia (SaO 2 < 90) in OSA group due to endobronchial migration of endotracheal tube. There were no differences between the groups with regards to intraoperative opioid use.
At the end of procedure all patients were safely extubated in the operating room. Their immediate post-operative care was in the PACU for all patients except one. This patient with OSA was electively transferred to the ICU due to a history of severe aortic stenosis. There were no complications in the PACU. There were no differences in the post-operative destination from PACU between the two groups [Table 3].
Post-operative hypoxemia (SaO 2 <90%) occurred in 12 patients, 10 in OSA and 2 non-OSA groups. Seven patients with OSA required high flow oxygen by face mask starting on the post-operative day 0 (n = 3), day 2 (n = 2) and day 3 (n = 2). However three others did not respond to high flow oxygen and required CPAP on postoperative day two (n = 1) and post-operative day 3 (n = 2). None of these patients had a CSF leak and there were no complications with the use of CPAP. In the OSA negative group, on the day one, 2 patients required treatment with supplemental oxygen by using face mask. There were no differences between the groups with regards to other post-operative complications [Table 3].
| Discussion|| |
OSA is a common occurrence in patients with endocrine disorders presenting for transsphenoidal surgery. Incidences of perioperative airway and haemodynamic complications were higher in patients with OSA. In our retrospective review, we found that the incidence of difficult mask ventilation was higher in patients with OSA when compared to those without OSA. The incidence of intraoperative hypertension and hypotension were higher in OSA positive group. This can be due to the fact that the number of patients who had hypertension and diabetes mellitus were higher in OSA group.
The increased risk for perioperative airway compromise, especially in the early postoperative period is well documented in patients with OSA.  The use of CPAP to maintain a continuous level of positive airway pressure has been shown to decrease the incidence of post-operative respiratory complications in OSA patients. Patients with acromegaly have a high incidence of OSA and central sleep apnea. , The reasons for this OSA may be related to anatomical changes such as increase growth of the mandible and maxilla and oropharyngeal soft-tissue thickening leading to hyper collapsibility of the posterior and lateral hypopharyngeal walls.  Hypertrophy of the tongue and submaxillary glands also play a role. In Cushing's disease, the development of OSA has been related to weight gain and accumulation of adipose tissue in the subcutaneous tissues of the neck, including oral pharyngeal spaces and face. , Following transsphenoidal surgery there may be worsening of the OSA due to development of edema of the nose and oral airway, as well as the placement of any nasal packing or catheter. 
After transsphenoidal surgery the use of CPAP therapy may be difficult because of the nasal packing and also, there is a potential risk of developing pneumocephalus and meningitis following the CPAP therapy. After transsphenoidal surgery a one-way valve may develop between the intracranial contents and the nasopharynx. Pneumocephalus may occur when there is a decrease in the intracranial pressure due to a CSF leak or in the presence of CSF shunts. , The use of CPAP could also insufflate air into the cranium and can cause tension pneumocephalus. , In our retrospective review, the incidence of hypoxemia was higher in patients with OSA (26%) compared to non OSA group (5%) as proven by other studies. Most patients in OSA group received high flow oxygen therapy by facemask (70%) and only a few patients required CPAP (30%). Among the patients who received CPAP, most of them used it on the 3 rd postoperative day and none of them received on the same day of surgery. This may be the reason why none of the patients in our study developed the complication such as pneumocephalus, CSF leak, or meningitis after CPAP use. In our study, there were three patients in OSA group who had CSF leak but none required CPAP therapy during the immediate post-operative period. Since our number is very small, it is very difficult to determine the safe use CPAP after transsphenoidal surgery. In order to avoid the use of CPAP, other strategies to prevent OSA related hypoxemia include elective prophylactic tracheostomy or uvulopalatopharyngoplasty prior to transsphenoidal surgery and a double-lumen nasal airway to provide CPAP.  In our study none of the patients needed tracheostomy or double lumen nasal airway for providing CPAP during the postoperative period.
Despite similar post-operative opioid requirement in both groups the incidence of hypertension was higher in OSA negative group. This may possibly be due to higher incidence of undiagnosed and untreated hypertension in OSA negative group.
Limitations of our study include the retrospective nature of the data collection. All adverse events may not have been documented. Furthermore, the sample size of patients with sleep study proven OSA and the number of patients using CPAP was small, due to the use of STOP-BANG questionnaire as a screening tool. This may have resulted in having a low incidence of OSA in patients with acromegaly and Cushing's disease in our study population compared to other series.
| Conclusions|| |
Post-operative hypoxemia is more common in patients with OSA after transsphenoidal surgery, but this can be treated in most but not all patients with high flow oxygen using the face mask. We were able to safely use CPAP in a very small number of patients but caution is needed to prevent complications especially in presence CSF leak. Further prospective studies are needed to determine the safe use of CPAP in patients after transsphenoidal surgery.
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[Table 1], [Table 2], [Table 3]
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