Impact of obstructive sleep apnea in transsphenoidal pituitary surgery: An analysis of inpatient data

Expert Strategies: Skull Base Reconstruction-Global Perspectives, Insights, and Algorithms through a MixedMethods Approach

OBJECTIVE

There is limited consensus on endoscopic skull base surgery (ESBS) reconstruction principles. This study aims to generate comprehensive themes regarding ESBS reconstruction by pooling the experiences of ESBS experts, with comparison to a literature review of current published evidence.

METHODS

Structured qualitative interviews of ESBS experts regarding postoperative management and reconstruction of various defect locations were conducted.

RESULTS

A total of 68 experts comprising 40 academic teams across 13 countries with an average of 18 years of ESBS experience were included. We propose 10 stepwise algorithms for common skull base reconstruction scenarios based on these expert interviews. When available, the nasoseptal flap is used for all high_flow cerebrospinal leak defects. Multilayered reconstruction is favored at all anatomical subsites with increasing number of layers for increasing defect size and complexity. Heterogeneity exists in terms of inlay technique and materials, free grafting versus various pedicled flap options for low-flow defects or in the absence of a nasal septum, nasal packing, tissue sealant, lumbar drain use, and postoperative management. Commonalities and discrepancies between experts were summarized.

CONCLUSION

Skull base reconstruction and post-ESBS management is highly complex with a wide variety of practice patterns and expert strategies. Further research of higher quality evidence is warranted to identify optimal management patterns, though the current work aims to inform surgeons on these controversial areas by drawing from numerous experiences.

Postoperative Obstructive Sleep Apnea Management Following Endoscopic Pituitary Surgery: A Systematic Review

OBJECTIVE

There is currently no consensus on the appropriate timing of noninvasive positive pressure ventilation (PPV) resumption in patients with obstructive sleep apnea (OSA) after endoscopic pituitary surgery. We performed a systematic review of the literature to better assess the safety of early PPV use in OSA patients following surgery.

METHODS

The study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Databases in English were searched using the keywords: "sleep apnea," "CPAP," "endoscopic," "skull base," "transsphenoidal" and "pituitary surgery." Case reports, editorials, reviews, meta-analyses, unpublished and abstract-only articles were all excluded.

RESULTS

Five retrospective studies were identified, comprising 267 patients with OSA who underwent endoscopic endonasal pituitary surgery. The mean age of patients in four studies (n = 198) was 56.3 years (SD = 8.6) and the most common indication for surgery was pituitary adenoma resection. The timing of PPV resumption following surgery was reported in four studies (n = 130), with 29 patients receiving PPV therapy within two weeks. The pooled rate of postoperative cerebrospinal fluid leak associated with PPV resumption was 4.0% (95% CI: 1.3-6.7%) in three studies (n = 27) and there were no reports of pneumocephalus associated with PPV use in the early postoperative period (<2 weeks).

CONCLUSIONS

Early resumption of PPV in OSA patients after endoscopic endonasal pituitary surgery appears relatively safe. However, the current literature is limited. Additional studies with more rigorous outcome reporting are warranted to assess the true safety of re-initiating PPV postoperatively in this population.

Anesthetic management during transsphenoidal pituitary surgery

PURPOSE OF REVIEW

Pituitary adenoma resections comprise a large proportion of intracranial tumor surgeries. This patient population is medically and physiologically complex and requires careful perioperative planning and management on the part of the anesthesiologist. This review will summarize anesthetic considerations for pre, intra, and postoperative management of patients undergoing transsphenoidal pituitary surgery.

RECENT FINDINGS

An endoscopic approach is favored for patients undergoing transsphenoidal pituitary surgery. Hemodynamic monitoring is important to maintain cerebral perfusion and avoid risk of bleeding; however, 'controlled' hypotension may have adverse effects. Multimodal analgesia is effective for the management of postoperative pain and may reduce the risk of postoperative complications, including respiratory depression and postoperative nausea and vomiting.

SUMMARY

Transsphenoidal pituitary surgery is a preferred approach for the surgical management of nonfunctioning pituitary macroadenomas with symptoms of mass effect and functioning adenomas that cannot be otherwise managed medically. Understanding tumor pathologies and systemic effects are essential for preoperative planning and providing safe anesthetic care during the perioperative period.

Safety of restarting continuous positive airway pressure (CPAP) therapy following endoscopic endonasal skull base surgery

Objectives

Patients with obstructive sleep apnea (OSA) are at increased risk of perioperative and postoperative morbidity. The use of continuous positive airway pressure (CPAP) in the perioperative period may be of potential benefit. However, among patients who have undergone endonasal skull base surgery, many surgeons avoid prompt re‐initiation of CPAP therapy due to the theoretical increased risk of epistaxis, excessive dryness, pneumocephalus, repair migration, intracranial introduction of bacteria, and cerebrospinal fluid (CSF) leak. The objective of this article is to review the most up‐to‐date literature regarding when it is safe to resume CPAP usage in the patient undergoing endonasal skull base surgery.

Data Sources and Methods

This review combines the most recent literature as queried through PubMed regarding the safety of CPAP resumption following endonasal skull base surgery.

Results

Recent surveys of skull base surgeons demonstrate little consensus regarding the post‐operative management of OSA. Recent cadaveric studies suggest that approximately 85% of delivered CPAP pressures are transmitted to the sphenoid sinus. Further, at frequently prescribed CPAP pressure settings, common sellar reconstruction techniques maintain their integrity while preventing very little transmission of pressure into the sella. In small retrospective case series, patients with OSA who received CPAP immediately following transsphenoidal pituitary surgery had similar rates of surgical complications as OSA patients who did not receive CPAP in the immediate post‐operative period. Concerns of re‐initiating CPAP too early, such as the development of pneumocephalus, rarely develop.

Conclusions

There remains a paucity of objective data regarding when it is safe to resume CPAP following endonasal skull base surgery. Recent cadaveric studies and small retrospective case series suggest that it may be safe to resume CPAP earlier than is often practiced following endonasal skull base surgery.

There is no consensus regarding the time course of when it is safe to resume CPAP therapy following endonasal skull base surgery.

Following endonasal skull base surgery there are potentially unique risks of initiation of CPAP including epistaxis, excessive nasal crusting/drying, graft migration, pneumocephalus, CSF leak, and intracranial introduction of bacteria.

Cadaveric modeling suggests that only a fraction of the delivered CPAP pressure is actually transmitted into the sella, and even the simplest sellar repair techniques can withstand low to moderate pressures.

Small case series' do not demonstrate increased rate of post‐operative complications in patients with OSA who received CPAP immediately after surgery.

The decision to start CPAP postoperatively must be tailored to each patient based on the severity of his/her OSA, intraoperative findings, and the type of skull base repair employed.

Prediction of Readmission and Complications After Pituitary Adenoma Resection via the National Surgical Quality Improvement Program (NSQIP) Database

Introduction Pituitary adenomas are common intracranial tumors (incidence 4:100,000 people) with good surgical outcomes; however, a subset of patients show higher rates of perioperative morbidity. Our goal was to identify risk factors for postoperative complications or readmission after pituitary adenoma resection. Methods We undertook a retrospective cohort study of patients who underwent surgery for pituitary adenoma in 2006-2018 by using the National Surgical Quality Improvement Program database. The main outcome measures were patient complications and the 30-day readmission rate. Results Among the 2,292 patients (mean age 53.3±15.9 years), there were 491 complications in 188 patients (8.2%). Complications and 30-day readmission have remained stable over time rather than declined. Unplanned readmission was seen in 141 patients (6.2%). Multivariable analysis demonstrated that hypertension (OR=1.6; 95% CI= 1.1, 2.1; p=0.005) and high white blood cell count (OR=1.08; 95% CI=1.03, 1.1; p=0.0001) were independent predictors of complications. Return to the operating room (OR=5.9, 95% CI=1.7, 20.2, p=0.0005); complications (OR=4.1, 95% CI=1.6, 10.6, p=0.004); and blood urea nitrogen (OR=1.08, 95% CI=1.02, 1.2, p=0.02) were independent predictors of 30-day readmission. Conclusion Using one of the largest datasets of pituitary adenoma patients, we identified perioperative factors most critical for patient outcome. One strength of this study is adjusting for cofactors that predict outcomes, which has not been done previously. Several patient biomarkers, namely white blood cell count and blood urea nitrogen, may serve as preoperative markers that might identify patients at higher risk. Control of blood pressure and renal disease may be perioperative management strategies that can impact the outcome.

Preoperative Screening for Obstructive Sleep Apnea Prior to Endoscopic Skull Base Surgery: A Survey of the North American Skull Base Society

Background

Obstructive sleep apnea (OSA) is a commonly seen comorbidity in patients undergoing endoscopic skull base surgery and its presence may influence perioperative decision-making. Current practice patterns for preoperative screening of OSA are poorly understood.

Objective

The objective of this study was to assess how endoscopic skull base surgeons screen for OSA, and how knowledge of OSA affects perioperative decision-making.

Methods

Seven question survey distributed to members of the North American Skull Base Society.

Results

Eighty-eight responses (10% response rate) were received. 60% of respondents were from academic centers who personally performed >50 cases per year. Most respondents noted that preoperative knowledge of OSA and its severity affected postoperative care and increased their concern for complications. Half of respondents noted that preoperative knowledge of OSA and its severity affects intraoperative skull base reconstruction decision-making. 70% of respondents did not have a preoperative OSA screening protocol. Body mass index and patient history were most frequently used by those who screened. Validated screening questionnaires were rarely used. 76% of respondents agreed or somewhat agreed that a preoperative polysomnogram should ideally be performed for patients with suspected OSA; however, 50% of respondents reported that <20% of their patients with suspected OSA are advised to obtain a preoperative polysomnogram.

Conclusion

This study reveals that most endoscopic skull base surgeons agree that OSA affects postoperative patient care, but only a minority have a preoperative screening protocol in place. Additional study is needed to assess the most appropriate screening methods and protocols for OSA patients undergoing endoscopic skull base surgery.

Qualitative Assessment of the Effect of Continuous Positive Airway Pressure on the Nasal Cavity

BACKGROUND

For patients with obstructive sleep apnea (OSA), there is a lack of knowledge regarding the impact of continuous positive airway pressure (CPAP) on the nasal cavity. There is a significant need for evidence-based recommendations regarding the appropriate use of CPAP following endoscopic sinus and skull base surgery.

OBJECTIVE

The goal of this study is to translate a previously developed cadaveric model for evaluating CPAP pressures in the sinonasal cavity by showing safety in vivo and quantifying the effect of positive pressurized air flow on the nasal cavity of healthy individuals where physiologic effects are at play.

METHODS

A previously validated cadaveric model using intracranial sensor catheters has proved to be a reliable technique for measuring sinonasal pressures. These sensors were placed in the nasal cavity of 18 healthy individuals. Pressure within the nose was recorded at increasing levels of CPAP.

RESULTS

Overall, nasal cavity pressure was on average 85% of delivered CPAP. The amount of pressure delivered to the nasal cavity increased as the CPAP increased. The percentage of CPAP delivered was 77% for 5 cmH₂O and increased to 89% at 20 cmH₂O. There was a significant difference in mean intranasal pressures between all the levels of CPAP except 5 cmH₂O and 8 cmH₂O (P < .001).

CONCLUSION

On average, only 85% of the pressure delivered by CPAP is transmitted to the nasal cavity. Higher CPAP pressures delivered a greater percentage of pressurized air to the nasal cavity floor. Our results are comparable to the cadaver model, which demonstrated similar pressure delivery even in the absence of anatomic factors such as lung compliance, nasal secretions, and edema. This study demonstrates the safety of using sensors in the human nasal cavity. This technology can also be utilized to evaluate the resiliency of various repair techniques for endoscopic skull base surgery with CPAP administration.

A cadaveric model for measuring sinonasal continuous positive airway pressure-a proof-of-concept study

BACKGROUND

Obstructive sleep apnea is a common respiratory disorder that can have negative effects on health and quality of life. Positive pressure therapy (CPAP) is the primary treatment. There is a lack of consensus on the risk of postoperative CPAP after endoscopic sinus or skull base surgery. We present a proof-of-concept cadaver model for measuring sinonasal pressure delivered by CPAP.

METHODS

Three fresh cadaver heads were prepared by removing the calvaria and brain. Sphenoidotomies were made and sellar bone was removed. Pressure sensors were placed in the midnasal cavity, sphenoid sinus, and sella. CPAP was applied and the delivered pressure was recorded at increasing levels of positive pressure. Paired t tests and intraclass correlation coefficients were used to analyze results.

RESULTS

Increases in positive pressure led to increased pressure recordings for all locations. Nasal cavity pressure was, on average, 81% of delivered CPAP. Pressure was highest in the sphenoid sinus. The effect of middle turbinate medialization on intrasphenoid pressure was not statistically significant in 2 heads. Intrasellar pressure was 80% of delivered CPAP with lateralized turbinates and 84% with medialized turbinates. Pressure recordings demonstrated excellent reliability for all locations. All heads developed non-sellar-based cranial base leaks at higher pressures. Cribriform region leaks were successfully sealed with DuraSeal®.

CONCLUSION

Our proof-of-concept cadaver model represents a novel approach to measure pressures delivered to the nasal cavity and anterior skull base by CPAP. With further study, it may have broader clinical application to guide the safe postoperative use of CPAP in this population.

Evaluation of the pharyngeal airway using computational fluid dynamics in patients with acromegaly

Objectives

Perioperative airway management may be particularly challenging in patients with acromegaly undergoing trans‐sphenoidal pituitary surgery (TSS). Management for airway obstruction is required prior to pituitary surgery to minimize perioperative hypoxia. The purpose of this retrospective study was to evaluate airway obstruction by simulation of computational fluid dynamics (CFD) using computed tomography (CT) images in patients who had undergone TSS.

Methods

CT images of the nasopharyngeal airways of patients with acromegaly (n = 5) or nonfunctional pituitary adenoma (n = 6) undergoing TSS from April 2012 to January 2017 were used to construct these airways in three dimensions. Estimated airflow pressure and velocity in the retropalatal airway (RA), oropharyngeal airway (OA), and hypopharyngeal airway (HA) were simulated using CFD.

Results

Estimated pharyngeal airflow pressure in the HA, OA, and RA was significantly greater in patients with acromegaly than in those with nonfunctional pituitary adenomas whereas the estimated pharyngeal airflow velocity was significantly impaired only in the RA of patients with acromegaly. Minimum postoperative SpO₂ both within 3 hours and from 3 to 12 hours after the end of anesthesia was significantly lower in the patients with acromegaly. Additionally, estimated volume of tongue and pharyngeal airflow pressure in the HA, OA, and RA correlated with minimum postoperative SpO₂.

Conclusion

Pharyngeal airflow pressure estimated from CT images is high in patients with acromegaly, and these values correlate with postoperative minimum values for SpO₂. Preoperative evaluation of CT images by CFD can predict difficulty in airway management and perioperative hypoxia.

Level of Evidence

4.