General Anesthesia Using Laryngeal Mask Airway Ventilation With Low-Dose Neuromuscular Blockade Is Safe and Effective for Patients Undergoing Hip Arthroscopy

Purpose

To investigate safety and efficacy of a general anesthesia protocol using laryngeal mask airway (LMA) ventilation without endotracheal intubation (ETT) in the setting of a low dosage of neuromuscular blockade (NMBA) for patients undergoing hip arthroscopy.

Methods

Patients who underwent hip arthroscopy for femoroacetabular impingement syndrome at a single institution from 2014 to 2024 were retrospectively analyzed. Those who underwent hip arthroscopy for non-femoroacetabular impingement syndrome indications and those with a concomitant periacetabular osteotomy were excluded. General anesthesia was administered with propofol and sevoflurane, with LMA ventilation. A low-dose (10-50 mg) NMBA agent (rocuronium) was given before hip distraction. The primary outcome of interest was pulmonary aspiration. Secondary outcomes of interest included conversion to ETT and operating room time.

Results

This study included 1,169 cases (49.8% female) with mean age 37.8 years (± 11.0) and body mass index 24.4 (± 3.9). In total, 64.0% were American Society of Anesthesiologists (ASA) class I, 34.8% class II, and 1.2% class III. In 24 cases, patients underwent ETT without attempting LMA as a result of preoperative aspiration risk factors. Of the 1,145 cases that underwent LMA with NMBA, mean dose of rocuronium given was 20.4 mg, and no patients experienced pulmonary aspiration or anesthesia complications. Twenty-one cases (1.8%) required conversion to ETT as the result of poor LMA fit or ventilation leakage. ASA class was not associated with LMA-to-ETT conversion ( P =.77). Mean airway manipulation time was 6.0 minutes (± 6.4), mean procedure duration was 100.3 minutes (± 48.7), and mean procedure end to airway removal time- 5.0 minutes (± 5.0). No surgical complications related to hip distraction or traction force occurred.

Conclusions

Administration of general anesthesia using LMA ventilation with a low dosage of neuromuscular blockade is safe and effective for patients undergoing hip arthroscopy. The rate of conversion to endotracheal intubation was low and showed no association with ASA classification.

Level of Evidence

Level IV, retrospective therapeutic case series.

Hip arthroscopy increasingly is performed in outpatient settings in the United States. Protocols to improve patient safety and surgical efficiency are evolving. The use of a neuromuscular blocking agent (NMBA) can help facilitate the distraction of the hip joint. These agents decrease the force required for adequate distraction of the hip joint, which improves patient safety, because increased duration and applied traction force are associated with nerve palsy. ^,

Variability in anesthesia practice exists regarding airway management with the use of NMBAs (i.e., rocuronium), with many providers preferring endotracheal intubation over laryngeal mask airway (LMA) ventilation. Compared with LMA, the use of endotracheal tubes (ETTs) can result in an increased incidence of dysphonia and pharyngeal discomfort. LMA can be easier and faster to insert in some patients, ^, with lower postairway removal morbidity reported. However, the primary concern with using rocuronium without an ETT is the risk of gastric insufflation during positive pressure ventilation. This ventilation technique is often necessary when NMBAs are used, because they induce diaphragmatic paralysis. Positive pressure ventilation with an LMA may increase the chance of insufflation of the stomach, resulting in a theoretical increased risk of pulmonary aspiration. ^,^,^,^, Other risk factors for aspiration include body mass index (BMI), previous gastric/esophageal surgery, gastrointestinal obstruction, delayed gastric emptying, and glucagon-like peptide-1 receptor agonists such as semaglutide. ^,^, Because the use of LMA ventilation during hip arthroscopy may improve operating room efficiency and decrease the side effects associated with endotracheal intubation, it may be valuable to evaluate the risk of aspiration when an LMA is used in conjunction with neuromuscular blockage. ^,^,^,

The purpose of this study was to investigate the safety and efficacy of a general anesthesia protocol using LMA ventilation without endotracheal intubation in the setting of a low dosage (10-50 mg) of neuromuscular blockage for patients undergoing hip arthroscopy surgery. We hypothesized that no major adverse complications, pulmonary aspiration being the primary outcome of interest, would be observed in patients undergoing hip arthroscopy with a combined NMBA-LMA anesthetic protocol.

Methods

This study was approved by the institutional review board (24-42503).

Patient Selection

Patients were included if they underwent hip arthroscopy for femoroacetabular impingement syndrome (FAIS) between January 2014 and September 2024. Exclusion criteria included hip arthroscopy for non-FAIS indications and patients who underwent concomitant periacetabular osteotomy. This study was approved by the institutional review board.

Anesthesia Protocol

Patients undergoing hip arthroscopy were seen in a preoperative anesthesia clinic. Risk factors for pulmonary aspiration (i.e., obesity and obstructive sleep apnea) and other anesthetic considerations were evaluated at this time. Patients taking glucagon-like peptide 1 receptor agonists (semaglutide) were instructed to pause taking their medication 10 days before surgery. Intravenous induction of general anesthesia was performed using propofol, with time and dosage depending on anesthesiologists’ preference. An LMA was placed postinduction, before the administration of NMBAs. LMA types available were as follows: air-Q (CookGas; Mercury Medical, Clearwater, FL), i-gel (Intersurgical, Wokingham, England), LMA-Classic (Teleflex, Morrisville, NC), LMA-Supreme (Teleflex), LMA-Unique (Teleflex), and LMA-ProSeal (Teleflex). After the LMA was secured with tape, the patient was positioned into traction boots. Once positioned, a series of fluoroscopic images were taken. After completion of imaging, the anesthesia provider administered rocuronium, typically 10 to 50 mg. Rocuronium dosage was based on anesthesiologist preference: either weight based (0.5 mg/kg) or starting with an initial 20-mg dose and then redosed in 10-mg increments up to 50 mg if central compartment distraction was difficult or muscle spasm occurred. The most commonly used ventilator mode was pressure support ventilation, and transitioned to a controlled mechanical ventilation mode, most often synchronized intermittent mandatory ventilation-pressure control volume guarantee mode, if diaphragmatic paralysis occurred after rocuronium administration. At the conclusion of the procedure, sugammadex was administered in a weight-based fashion (typically 2 mg/kg; however, a practical dose of 200 mg used frequently because of vial size) if indicated for reversal of rocuronium.

Surgical Technique

All patients included in the study were indicated for hip arthroscopy of the central compartment for FAIS. Surgeries were performed in an ambulatory surgery center by 2 fellowship-trained orthopaedic sports surgeons with expertise in hip arthroscopy (A.L.Z. and S.E.W.). Patients were positioned supine on a postless table specific for hip arthroscopy (Pivot Guardian; Stryker, Kalamazoo, MI) or a hip distraction attachment with a large diameter perineal post (Hip Positioning System; Smith & Nephew, Andover, MA). After induction of general anesthesia and securing of the airway, a 17-gauge spinal needle was used to perform an air arthrogram to aid in distraction of the hip joint. After fluoroscopic confirmation of the air arthrogram, manual traction was applied across the central compartment. After fluoroscopic confirmation of hip distraction, fluoroscopy was used to gain central compartment access first through an anterolateral portal, and then a midanterior portal. Interportal or periportal capsulotomy was performed according to surgeon preference and patient selection. Diagnostic arthroscopy was performed, followed by arthroscopic labral repair, debridement, or reconstruction. Acetabuloplasty was performed when indicated. After central compartment pathology was addressed, traction was released, and peripheral compartment pathology was managed (femoroplasty). Closure of the hip capsule was performed if interportal capsulotomy was elected or on a case-by-case basis when periportal capsulotomy was used.

Patients were assessed for age, weight, BMI, history of gastric/esophageal surgery, hiatal hernia, American Society of Anesthesiologists (ASA) physical status classification, and symptomatic gastroesophageal reflux disease. The primary outcome investigated in this study was pulmonary aspiration, with secondary outcomes being conversion to endotracheal intubation and surgical times.

Statistical Analysis

χ ² analysis was employed to evaluate associations between categorical variables, with a significance level set at P <.05.

Results

Demographic and Anesthesia Characteristics

The sample included 1,169 cases of hip arthroscopy, of which 1,014 unique patients were identified. This series of hips included 582 female (49.8%) and 587 male (50.2%) patients. The mean age of the study population was 37.8 years (± 11.0), and the mean BMI was 24.4 (± 3.9). No patients had a history of hiatal hernia or previous gastric/esophageal surgery.

ASA categories were as follows for the study population at the time of surgery: class I (normal, healthy patient) 748 (64.0%), class II (patient with mild systemic disease) 407 (34.8%), class III (patient with severe systemic disease) 14 (1.2%) ( Table 1 ). Of cases where the LMA design was recorded in the medical record (n = 948), the most common LMA types were as follows: i-gel (484, 51.1%), LMA-Unique (172, 18.1%), LMA-Supreme (132, 13.9%), LMA-ProSeal (108, 11.4%), LMA-Classic (51, 5.4%), and Air-Q (1, 0.1%).

Table 1

Preoperative Demographic Characteristics (n = 1,169)

Characteristic	Results
Sex
Female	582 (49.8)
Male	587 (50.2)
Age, yr	37.8 ± 11.0
ASA status
Class I	748 (64.0)
Class II	407 (34.8)
Class III	14 (1.2)
BMI	24.4 ± 3.9
History of gastric or esophageal surgery	0
Presence of hiatal hernia	0

NOTE. Continuous data listed as mean ± standard deviation. Nominal data listed as number (%).

ASA, American Society of Anesthesiologists; BMI, body mass index.

Every patient received a dose of rocuronium. 397 (34.0%) received a dose of 10 mg, 78 (6.7%) received 15 mg, 313 (26.8%) received 20 mg, 32 (2.7%) received 25 mg, 170 (14.5%) received 30 mg, 3 (0.3%) received 35 mg, 33 (2.8%) received 40 mg, and 70 (6.0%) received 50 mg. 54 (4.6%) received a dose less than 10 mg, and 19 (1.6%) received a dose more than 50 mg; the minimum dose was 2.0 mg, and the maximum dose was 100 mg. The mean dosage was 20.4 mg (± 13.2) ( Fig 1 ). In total, 536 (45.9%) patients received sugammadex at the conclusion of case. 61.2% received 100 or 200 mg, with a mean dose of 168.5 mg (± 52.7).

Image, AltText currently not available — Fig 1

In 24 of 1,169 cases (2.1%), an ETT was placed without an LMA attempt. In this cohort of patients, the following comorbidities were reported on their preoperative anesthesia evaluation: 10 of 24 symptomatic gastroesophageal reflux disease, 9 of 24 snoring, 4 of 24 obstructive sleep apnea, 14 of 24 obesity (BMI ≥30), 6 of 24 thyromental distance between 4.5 and 6 cm, 1 of 24 history of unilateral Bell palsy, and 3 of 24 Mallampati class III. In total 16 of 24 patients were documented as having at least 2 of these reported risk factors ( Table 2 ).

Table 2

Preoperative Anesthesia Characteristics of Patients Who Underwent Endotracheal Intubation (n = 24)

Characteristic	Results
Symptomatic GERD	10 (41.7)
History of snoring	9 (37.5)
Obstructive sleep apnea	4 (16.7)
Obesity (BMI ≥30)	14 (58.3)
Thyromental distance 4.5-6 cm	6 (25.0)
History of unilateral Bell palsy	1 (4.2)
Mallampati class III	3 (12.5)
Two or more aspiration risk factors	16 (66.7)

NOTE. Nominal data listed as number (%).

BMI, body mass index; GERD, gastroesophageal reflux disease.

Operative Times

The mean time spent manipulating the airway was 6.0 minutes (± 6.4). The procedure duration was a mean of 100.3 minutes (± 48.7), and the mean procedure end time to airway removal time was 5.0 minutes (± 5.0) ( Table 3 ).

Table 3

Operative Times