Evaluation of patient state index, bispectral index, and entropy during drug induced sleep endoscopy with dexmedetomidine.

Multiple electroencephalographic (EEG) monitors and their associated EEG markers have been developed to aid in assessing the level of sedation in the operating room. While many studies have assessed the response of these markers to propofol sedation and anesthetic gases, few studies have compared these markers when using dexmedetomidine, an alpha-2 agonist. Fifty-one patients underwent drug induced sleep endoscopy with dexmedetomidine sedation. Continuous EEG was captured using SedLine (Masimo, Inc), and a playback system was used to extract the bispectral index (BIS) (Medtronic Inc), the patient state index (PSI) (Masimo, Inc), the state and response Entropy (GE Healthcare), and calculate the spectral edge frequency 95% (SEF95). Richmond Agitation-Sedation Scale (RASS) scores were assessed continually throughout the procedure and in recovery. We assessed the correlation between EEG markers and constructed ordinal logistic regression models to predict the RASS score and compare EEG markers. All three commercial EEG metrics were significantly associated with the RASS score (p < 0.001 for all metrics) whereas SEF95 alone was insufficient at characterizing dexmedetomidine sedation. PSI and Entropy achieved higher accuracy at predicing deeper levels of sedation as compared to BIS (PSI: 58.3%, Entropy: 58.3%, BIS: 44.4%). Lightening secondary to RASS score assessment is significantly captured by all three commercial EEG metrics (p < 0.001). Commercial EEG monitors can capture changes in the brain state associated with the RASS score during dexmedetomidine sedation. PSI and Entropy were highly correlated and may be better suited for assessing deeper levels of sedation.

Difficult Tracheal Intubation and Airway Outcomes after Radiation for Nasopharyngeal Carcinoma.

OBJECTIVE: The aim of the study was to characterize the incidence and management of difficult tracheal intubations (DTIs) in nasopharyngeal carcinoma (NPC) after primary radiation therapy (RT). METHODS: The study was a retrospective review of airway assessment and outcomes in post-RT NPC patients. Primary analysis was performed on patients who underwent post-RT procedures, who were split into non-DTI and DTI groups. Patients were classified as DTI if they (i) required >1 attempt to intubate, (ii) failed to be intubated, or (iii) experienced complications attributed to airway management. Secondary analysis was performed between patients who underwent post-RT procedures (procedure group) and those who did not (control group). RESULTS: One-hundred and fifty patients were included, and 71.3% underwent post-RT procedures, with no differences in characteristics between the procedure and control groups. One-hundred and fifty procedures were identified, and 28.0% were categorized as DTI. There was no difference in patient characteristics or airway assessment measures between DTI and non-DTI groups. Regression analysis revealed concurrent cervical mobility restriction, and trismus increased DTI incidence by 7.1-fold (p = 0.011). Being non-White was an independent predictor of DTI. The incidence of high-grade intraoperative laryngoscopic view was lower in the non-DTI compared to the DTI group (20.4% vs. 64.3%, p < 0.0001). Failure to intubate occurred in 2.0% of cases, and 6.0% cases had perioperative complications. Based on preoperative assessment, sensitivity of predicting DTI was 54.8% and specificity was 63.9%. CONCLUSION: NPC patients frequently undergo post-RT procedures requiring complex airway management. Rates of DTI and failed intubation are significantly higher than those in the general surgical population, and the ability to predict DTI with standard preoperative airway measures is poor. LEVEL OF EVIDENCE: 4 Laryngoscope, 134:120-126, 2024.

Safety and Utility of Transnasal Humidified Rapid-Insufflation Ventilatory Exchange (THRIVE) for Laser Laryngeal Surgery.

OBJECTIVE: Transnasal humidified rapid-insufflation ventilatory exchange (THRIVE) is gaining acceptance as a safe method for apneic ventilation and oxygenation during laryngeal procedures, but remains controversial during laser laryngeal surgery (LLS) due to the theoretical risk of airway fire. This study describes our experience with THRIVE during LLS. STUDY DESIGN: Retrospective cohort study. SETTING: Stanford University Hospital, October 15, 2015 to June 1, 2021. METHODS: Retrospective chart review of patients ≥18 years who underwent LLS involving the CO2 or KTP laser with THRIVE as the primary mode of oxygenation. RESULTS: A total of 172 cases were identified. 20.9% were obese (BMI ≥ 30). Most common operative indication was subglottic stenosis. The CO2 laser was used in 79.1% of cases. Median lowest intraoperative SpO2 was 96%. 44.7% cases were solely under THRIVE while 16.3% required a single intubation and 19.2% required multiple intubations. Mean apnea time for THRIVE only cases was 32.1 minutes and in cases requiring at least one intubation 24.0 minutes (p < .001). Mean apnea time was significantly lower for patients who were obese (p < .001) or had a diagnosis of hypertension (p = .016). Obese patients and patients with hypertension were 2.03 and 1.43 times more likely to require intraoperative intubation, respectively. There were no intraoperative complications or fires since the institution of our LLS safety protocol. CONCLUSION: By eliminating the fuel component of the fire triangle, THRIVE can be safely used for continuous delivery of high FiO2 during LLS, provided adherence to institutional THRIVE-LLS protocols.

EEG response of dexmedetomidine during drug induced sleep endoscopy.

Introduction: Dexmedetomidine is one of the anesthetics of choice for drug induced sleep endoscopy (DISE), with advantages including limited respiratory depression, analgesia, and decreased incidence of emergence delirium. However, challenges with determining sedation levels and prolonged recovery have limited its usage. An improved understanding of the effect of dexmedetomidine on the level of sedation and the corresponding electroencephalographic (EEG) changes could help overcome these barriers. Methods: Fifty-one patients received dexmedetomidine sedation with Richmond Agitation-Sedation Scale (RASS) score assessment and continuous EEG monitoring via SedLine for DISE. We constructed a pharmacokinetic model to determine continuous dexmedetomidine blood concentration. From the SedLine, we extracted the patient state index (PSI), and from the EEG we calculated the spectral edge frequency 95% (SEF95) and the correlation dimension (CD), a type of fractal dimension used to assess the complexity of a system. These metrics were subsequently compared against one another and with the dexmedetomidine concentration. Results: Our pharmacokinetic model yielded a two-compartment model with volumes of 51.8 L and 106.2 L, with clearances of 69.5 and 168.9 L/h, respectively, and a time to effect of 9 min, similar to prior studies. Based on this model, decreasing RASS score, SEF95, CD, and PSI were all significantly associated with increasing dexmedetomidine concentration (p < 0.001, p = 0.006, p < 0.001 respectively). The CD, SEF95, and PSI better captured the effects of increasing dexmedetomidine concentration as compared to the RASS score. Simulating dexmedetomidine concentration based on titration to target levels derived from CD and PSI confirmed commonly used dexmedetomidine infusion dosages. Conclusion: Dexmedetomidine use for DISE confirmed previous pharmacokinetic models seen with dexmedetomidine. Complex EEG metrics such as PSI and CD, as compared to RASS score and SEF95, better captured changes in brain state from dexmedetomidine and have potential to improve the monitoring of dexmedetomidine sedation.

The Safety and Efficacy of Transnasal Humidified Rapid-Insufflation Ventilatory Exchange for Laryngologic Surgery.

OBJECTIVES: Transnasal humidified rapid-insufflation ventilatory exchange (THRIVE) is an intraoperative ventilatory technique that allows avoidance of tracheal intubation (TI) or jet ventilation (JV) in selected laryngologic surgical cases. Unimpeded access to all parts of the glottis may improve surgical precision, decrease operative time, and potentially improve patient outcomes. The objective of this prospective, randomized, patient-blinded, 2-arm parallel pilot trial was to investigate the safety and efficacy of THRIVE use for adult patients undergoing nonlaser laryngologic surgery of short-to-intermediate duration. METHODS: Twenty adult, American society of anesthesiology class 1-3 patients with body mass index (BMI) < 35 kg/m2 were randomly assigned to either an experimental THRIVE group or active comparator conventional ventilation group (TI or supraglottic high-frequency JV [SHFJV]). Primary outcomes included intraoperative oxygenation, anesthesia awakening/extubation time, time to laryngoscopic suspension, number of intraoperative suspension adjustments, and operative time. Secondary patient outcomes including postanesthesia and functional patient recovery were investigated. RESULTS: Compared to TI/SHFJV, THRIVE use was associated with significantly lower intraoperative oxygenation (SpO2 93.0 ± 5.6% vs. 98.7 ± 1.6%), shorter time to suspension (1.8 ± 1.1 minutes vs. 4.3 ± 2.1 minutes), fewer suspension adjustments (0.4 ± 0.5 vs. 1.7 ± 0.9), and lower postoperative pain scores on recovery room admission (1.3 ± 1.9 vs. 3.7 ± 2.9) and discharge (0.9 ± 1.3 vs. 2.7 ± 1.8). The study was underpowered to detect other possible outcome differences. CONCLUSION: We confirm the safe intraoperative oxygenation profile of THRIVE for selected patients undergoing nonlaser laryngologic surgery of short-to-intermediate duration. THRIVE facilitated surgical exposure and improved early patient recovery, suggesting a potential economic benefit for outpatient laryngologic procedures. The results of this exploratory study provide a framework for designing future adequately powered THRIVE trials. TRIAL REGISTER: ClinicalTrials.gov (NCT03091179). LEVEL OF EVIDENCE: II Laryngoscope, 2020.

The effect of deliberate hypercapnia and hypocapnia on intraoperative blood loss and quality of surgical field during functional endoscopic sinus surgery.

BACKGROUND: Anesthetic management during functional endoscopic sinus surgery is aimed at minimizing bleeding and establishing a near-perfect surgical field. We investigated whether deliberate intraoperative hypercapnia and hypocapnia may affect blood loss and quality of surgical field through a proposed modulating effect of different carbon dioxide (CO2) tension levels on nasal vasculature. METHODS: One hundred and eighty patients were randomly assigned to normocapnia (end-tidal CO2 [ETco2] 37 +/- 2 mm Hg), hypercapnia (ETco2 60 +/- 2 mm Hg), and hypocapnia (ETco2 27 +/- 2 mm Hg) groups. Anesthetic management was with propofol and remifentanil infusions, nitrous oxide, and moderate controlled hypotension. Blood loss and operating conditions were assessed by the surgeon who was blinded to group assignment. Differences among the study groups, the effect of the study group and time on ETco2 levels and hemodynamic variables, and the association of blood loss with surgical covariates were analyzed. RESULTS: There were no differences in blood loss and quality of surgical field among the study groups. Patients in the hypocapnia group demonstrated the highest, and in the hypercapnia group, the lowest, requirements for remifentanil, labetalol, and administration of the antihypertensive medications in general. The computed tomography-graded severity of sinonasal disease and duration of surgery were the only independent predictors of intraoperative blood loss. CONCLUSIONS: CO2 management during functional endoscopic sinus surgery does not influence operating conditions or blood loss.

The safety and efficacy of the use of the flexible laryngeal mask airway with positive pressure ventilation in elective ENT surgery: a 15-year retrospective single-center study.

BACKGROUND: The use of flexible laryngeal mask airway (FLMA) in elective ear, nose and throat (ENT) surgery offers significant advantages, but is frequently considered inferior to tracheal intubation (TI) for ventilation and airway protection. We investigated the safety and success rate of intraoperative FLMA use with positive pressure ventilation (PPV), and the factors responsible for FLMA failure. METHODS: A 15-year single center retrospective study. FLMA failure was defined as the need for FLMA removal and TI, either during induction (primary failure), or after turning the patient over to the surgeon (secondary failure). Strict failure criteria included the inability to achieve and/or maintain all 3 essential FLMA functions, such as ventilation (tidal volume ≥6 mL/kg), airway protection from above the cuff (airway sealing pressure [ASP] >12 cm H2O), and separation of the respiratory and gastrointestinal tracts (absent gastric insufflation during PPV). RESULTS: In 685 patients, FLMA was successfully inserted in 94%. Secondary failure rate was 1.5%, with half of failures observed intraoperatively. The inability to seat FLMA during induction or FLMA dislodgment were the most common reasons for failures. The number of FLMA insertion attempts and low ASP were associated with FLMA primary failure and the need for TI. There were no complications. CONCLUSIONS: The results suggest an acceptably low failure rate of use of FLMA with PPV in selected ENT surgical procedures. True intraoperative FLMA failure is uncommon. We advocate observing strict criteria for adequacy of FLMA placement, and close monitoring of FLMA function intraoperatively at all times.

The role of the craniospinal nerves in mediating the antinociceptive effect of transcranial electrostimulation in the rat.

Transcranial electrostimulation (TES) has been reported to elicit significant analgesia, but its mechanism of action has not been elucidated. In a recently introduced clinically relevant rat model of TES we have validated and characterized the TES antinociceptive effect, suggesting involvement of the sensory nerves of the rat's scalp in mediating that effect. In this study, we have further investigated the role of the craniospinal nerves by attempting to block the TES antinociceptive effect with local anesthetic injected under the TES electrodes. We also applied different transcutaneous electrical nerve stimulation modalities through the TES electrodes and compared the elicited antinociceptive effect to that of TES. The antinociceptive effect was assessed by measuring nociceptive thresholds in the tail-flick latency test in awake, unrestrained male rats. Data were analyzed by one-way analysis of variance followed by the Bonferroni t-test. The TES antinociceptive effect was significantly reduced after local anesthetic injection, and administration of 100 Hz transcutaneous electrical nerve stimulation was, over time, capable of eliciting the same degree of antinociceptive effect as TES. We conclude that sensory craniospinal nerves play a critical role in mediating the TES antinociceptive action and offer a hypothesis on the underlying mechanism(s) responsible for this action.

Variable Findings for Drug-Induced Sleep Endoscopy in Obstructive Sleep Apnea with Propofol versus Dexmedetomidine.

OBJECTIVE: To compare VOTE classification findings (velum, oropharyngeal-lateral walls, tongue base, and epiglottis) for drug-induced sleep endoscopy (DISE) among patients with obstructive sleep apnea (OSA) using 2 sedation protocols. STUDY DESIGN: Case series with chart review. SETTING: Single tertiary institution. SUBJECTS: Patients with OSA who underwent DISE. METHODS: A total of 216 patients underwent DISE between November 23, 2011, and May 1, 2015. DISE findings based on VOTE classification were compared between patients receiving the propofol- and dexmedetomidine-based sedation protocols. RESULTS: Patients with OSA (N = 216; age, 44.3 ± 11.7 years; body mass index, 27.9 ± 4.8 kg/m(2)) underwent DISE with intravenous administration of propofol (n = 52) or dexmedetomidine (n = 164). There were no statistically significant differences between the 2 groups in baseline apnea-hypopnea index, oxygen desaturation index, Mallampati score, tonsil size, Epworth Sleepiness Scale score, peripheral oxygen saturation nadir, age, sex, or body mass index. Patients in the propofol group had a significantly increased likelihood of demonstrating complete tongue base obstruction (75%, 39 of 52) versus partial or no obstruction (25%, 13 of 52) in the anterior-posterior dimension, as compared with the dexmedetomidine group (complete obstruction: 42.7%, 70 of 164; partial or no obstruction: 57.3%, 94 of 164; odds ratio: 4.0; 95% confidence interval: 2.0-8.1; P = .0001). Obstruction of other airway subsites was not significantly different. CONCLUSION: Use of propofol versus dexmedetomidine to induce sedation may have a significant effect on the pattern of upper airway obstruction observed during DISE. Randomized prospective studies are indicated to confirm these initial findings.

Chondronecrosis of the larynx following use of the laryngeal mask airway.

This case describes the development of laryngeal chondronecrosis after use of the laryngeal mask airway (LMA). A 69-year-old male with prior laryngeal irradiation underwent total knee replacement with general anesthesia via LMA. Postoperatively, he developed laryngeal chondronecrosis, bilateral vocal fold immobility, and aspiration, necessitating tracheostomy and gastrostomy placement. He improved with hyperbaric oxygen therapy, intravenous antibiotics, and endoscopic repair of a residual fistula. Vocal fold motion returned and he was decannulated. Chondronecrosis of the larynx may occur with the use of the LMA, and caution should be used in patients with a history of prior laryngeal irradiation.

Prevention of perioperative and anesthesia-related complications in facial cosmetic surgery.

Although office-based anesthesia for facial cosmetic surgery remains remarkably safe, no anesthesia or sedation performed outside the operating room should be considered minor. Proper organization, preparation, and patient selection, close collaboration with the surgeon, and expert and effective anesthesia care will increase patient safety and improve perioperative outcomes and patient satisfaction. This article presents a comprehensive overview of anesthesia in terms of facial plastic surgery procedures, beginning with a broad review of essentials and pitfalls of anesthesia, followed by details of specific anesthetic agents, their administration, mechanism of action, and complications.

The effectiveness of preemptive sphenopalatine ganglion block on postoperative pain and functional outcomes after functional endoscopic sinus surgery.

BACKGROUND: The sphenopalatine ganglion block (SPGB) with local anesthetic is used to treat facial pain and headache of various etiologies; it has been widely used during functional endoscopic sinus surgery (FESS). The purpose of this study was to investigate whether preemptive SPGB may positively impact postoperative pain and functional outcomes after FESS. METHODS: A prospective, double-blind, randomized, placebo-controlled study was performed. A total of 60 patients (18-70 years), undergoing general anesthesia for bilateral FESS, were randomly assigned to receive SPGB with either 2 mL 0.25% bupivacaine with epinephrine 1:100,000 (BP, treatment group) or normal saline (NS, control group). SPGB was performed preemptively 10 minutes before the start of surgery. Preoperative and postoperative (day 0, day 7, and day 30) visual analog pain scale, Sino-Nasal Outcome Test (SNOT-20), computed tomography (CT) and endoscopic scores were compared between the 2 groups. RESULTS: A total of 29 patients were enrolled in BP, and 27 were enrolled in NS. Three patients withdrew from the study, and 1 was withdrawn by the investigator due to severe hypertension after induction of anesthesia. There were no differences in patient demographic characteristics between the study groups. On day 7, the mean visual analog pain scales were 1.12 ± 0.3 in NS and 0.48 ± 0.23 in BP (p = 0.053). There were no statistical differences in other outcome measures (SNOT-20, CT and endoscopic scores) between the 2 groups. CONCLUSION: A limited trend toward reduced postoperative pain after FESS was noted with bupivacaine compared to saline, but statistical significance was not achieved. Preemptive SPGB may offer sinonasal symptomatic benefits for patients undergoing FESS, but larger studies are warranted.

Rigid bronchoscope-assisted endotracheal intubation: yet another use of the gum elastic bougie.

UNLABELLED: We describe a technique by which a gum elastic bougie (GEB) is used to facilitate an anticipated difficult endotracheal intubation in a patient undergoing rigid bronchoscopy. After placing the GEB through the lumen of the rigid bronchoscope, the GEB-suction catheter assembly was used to safely withdraw the bronchoscope in a manner mimicking the withdrawal of an intubating laryngeal mask airway (LMA) over the endotracheal tube using a stabilizer rod. The rationale for management and potential advantages of this approach versus use of an airway exchange catheter (including increased stability of an intubation guide) are discussed. IMPLICATIONS: We describe a technique of using a gum elastic bougie to facilitate an endotracheal intubation in a patient undergoing rigid bronchoscopy, which can be useful in a variety of clinical situations when the rigid bronchoscope is used in patients with abnormal airway.

The antinociceptive effect of transcranial electrostimulation with combined direct and alternating current in freely moving rats.

UNLABELLED: Transcranial electrostimulation (TES) has been reported to elicit significant analgesia, allowing a substantial reduction of intraoperative opioids. Acceptance of TES into clinical practice is hampered by lack of controlled clinical trials and inconclusive animal data regarding the TES antinociceptive action. This inconclusive data may be explained, in part, by failure in rat experiments to simulate the variables used in humans when TES electrodes are positioned on the skin. In this study we validated the TES antinociceptive effect in a novel animal model of cutaneously administered TES, when the stimulating conditions mimic the ones used in clinical practice. The antinociceptive effect was assessed by measuring nociceptive thresholds in the tail-flick and hot-plate latency tests in awake, unrestrained male rats. Data were analyzed by analysis of variance and mixed-effects population modeling. The administration of TES at 2.25 mA produced an almost immediate, sustained, frequency-dependent (40-60 Hz) antinociceptive effect, reaching approximately 50% of the maximal possible value. We conclude that an antinociceptive effect of cutaneously administered TES can be demonstrated in the rat. Some characteristics of the effect suggest an important role of the sensory nerves of the rat's scalp in mediating the TES antinociceptive response. IMPLICATIONS: Transcranial electrostimulation produces a significant, frequency-dependent antinociceptive effect that may be mediated by cutaneous nerves of the scalp.