Total i.v. anaesthesia with propofol and the laryngeal mask for orthopaedic surgery

Total intravenous anesthesia induced and maintained by a combination of remimazolam and remifentanil without a neuromuscular blocking agent: a prospective, observational pilot study

Background

A novel short-acting benzodiazepine, Remimazolam, has recently been approved for general anesthesia and sedation. Hence, we investigated the feasibility and safety of remimazolam during the induction and maintenance of general anesthesia without using a neuromuscular blocking agent (NMBA) in patients undergoing hysteroscopic surgery.

Methods

This prospective observational study included 38 patients undergoing hysteroscopic surgery. Remimazolam and remifentanil were the main anesthetic agents without an NMBA, and a supraglottic airway was inserted to protect the airway. The induction time, amount of each anesthetic agent used during anesthesia, intraoperative bispectral index (BIS) hemodynamic parameters, and recovery profiles were measured.

Results

General anesthesia was successfully administered to 37 patients using remimazolam and remifentanil without NMBA. The induction doses of remimazolam and remifentanil were 0.4 mg/kg (interquartile range [IQR] 0.34–0.47 mg/kg) and 1.07 μg/kg (IQR, 0.90–1.29 μg/kg), respectively. Additionally, the maintenance doses of remimazolam and remifentanil were 1.14 mg/kg/h (IQR, 0.88–1.55 mg/kg/h) and 0.06 μg/kg/min (IQR, 0.04–0.08 μg/kg/min), respectively. Intraoperative BIS values had risen temporarily > 60 in eight patients (21.6%) despite administration of 2 mg/kg/h of remimazolam; thus, they were treated with supplementary midazolam. The median recovery time was 7 min (IQR, 5–8 min) after 40 min (IQR, 40.0–57.5 min) of total mean anesthesia time. There was no correlation between the infusion dose of remimazolam and recovery profiles, such as recovery time, final BIS of anesthesia, modified observer assessment of alertness/sedation (OAA/S) scale or post-anesthesia recovery (PAR) score when arriving at the PACU, and length of stay in the PACU (all P > 0.05).

Conclusion

Remimazolam can be combined with remifentanil without an NMBA in female patients who undergo hysteroscopic surgery, during which a supraglottic airway is a feasible method to protect the airway.

Trial registration

The study protocol was registered at ClinicalTrials.gov (NCT05025410) on 27/08/2021.

Comparison between the Baska Mask® and I-Gel for Minor Surgical Procedures Under General Anaesthesia

Objective

Minor surgical procedures under general anaesthesia require a patent airway without the use of muscle relaxant. Supraglottic airway devices have been widely used for airway management. A study was undertaken to compare first-time insertion success rate, insertion time, sealing pressure and complications between the Baska^® mask and I-gel.

Methods

After approval from the institutional ethical committee, a randomised single-blinded study was conducted on 50 American Society of Anesthesiologists' physical status I and II female patients aged 18-40 years who underwent minor surgical procedures under general anaesthesia. Patients were randomly categorized into two groups of 25 each; group Baska^® mask and group I-gel, and the first-time success rate, mean insertion time and sealing pressure were measured. The results were analysed using unpaired t-test, Mann-Whitney U test, Chi-square test and ANOVA. A p value <0.05 was considered to be statistically significant.

Results

The first-time insertion success rate of the Baska^® mask was 21/24 (88%) when compared with the I-gel, which was 23/25 (92%) (p=0.585). The insertion time of the Baska^® mask was 14.9±6.2 s, whereas that of the I-gel was 14.7±4.4 s (p=0.877). The mean sealing pressure of the Baska^® mask was significantly higher when compared with the I-gel (28.9±3.5 vs. 25.9±2.5 cmH₂O) (p=0.001).

Conclusion

The Baska^® mask had a similar first-time insertion success rate and insertion time as the I-gel. The sealing pressure of the Baska^® mask was significantly greater than that of the I-gel. Both devices had complications that were comparable.

A comparative evaluation of ProSeal laryngeal mask airway, I-gel and Supreme laryngeal mask airway in adult patients undergoing elective surgery: A randomised trial

Background and Aims

Second-generation supraglottic airway devices are widely used in current anaesthesia practice. This randomised study was undertaken to evaluate and compare laryngeal mask airway: ProSeal laryngeal mask airway (PLMA), Supreme laryngeal mask airway (SLMA) and I-gel.

Methods

Eighty-four adult patients undergoing elective surgery were randomly allocated to three groups: group P (PLMA), group I (I-gel) and group S (SLMA) of 28 patients each. Insertion times, number of insertion attempts, haemodynamic response to insertion, ease of insertion of airway device and gastric tube, oropharyngeal leak pressure (OLP) and pharyngolaryngeal morbidity were assessed. The primary outcome measure was the OLP after successful device insertion. Statistical analysis was performed using Statistical Package for the Social Sciences version 18.0 software using Chi-squared/Fisher's exact test (categorical data) and analysis of variance (continuous data) tests. P < 0.05 was considered statistically significant.

Results

The demographic profile of patients was comparable. OLP measured after insertion, 30 minutes later and at the end of surgery differed significantly between the three groups (P < 0.001). The mean OLP was 32.64 ± 4.14 cm·H₂O in group P and 29.79 ± 3.70 cm·H₂O in group S. In group I, the mean OLP after insertion was 26.71 ± 3.45 cm H₂O, which increased to 27.36 ± 3.22 cm H₂O at 30 minutes and to 27.50 ± 3.24 cm H₂O towards the end of surgery. However, these increases were not statistically significant (P = 0.641). Device insertion time was longest for group P (P = 0.001) and gastric tube insertion time was longest for group I (P = 0.001). Haemodynamic response to insertion and pharyngolaryngeal morbidity were similar with all three devices.

Conclusion

PLMA provides better sealing pressure but takes longer to insert. I-gel and SLMA have similar sealing pressures. I-gel insertion time is quicker.

Clinical Comparison of I-Gel Supraglottic Airway Device and Cuffed Endotracheal Tube for Pressure-Controlled Ventilation During Routine Surgical Procedures

Objective

Recently, there has been a trend favouring the use of supraglottic airway devices over endotracheal tubes (ETT) during short surgical procedures. In this study, we are going to assess the suitability of one such supraglottic airway device, i-gel, for pressure-controlled ventilation (PCV) during routine surgical procedures.

Methods

The airway management for 60 patients was done with either i-gel (Group I) or cuffed tracheal tube (Group E) for this prospective, randomised, double-blinded study. Insertion time, number of attempts, ease of insertion and haemodynamic monitoring were recorded before, during and after insertion of these devices. Airway leak tests, leak volume and leak fraction were measured at 15, 20 and 25 cm H₂O PCV, and pharyngolaryngeal morbidity was evaluated postoperatively.

Results

I-gel is easier to insert than a tracheal tube (p=0.0056). The increase in heart rate and MAP was higher following insertion of tracheal tube in the first few minutes (p<0.001) and subsequently became comparable between the two groups. The leak volume and leak fraction between the two groups were comparable at 15 cm H₂O PCV, but significant difference was seen at 20 and 25 H₂O PCV between the two groups (p=0.232, p<0.001, p<0.001). Thirty minutes later, the leak volume and leak fraction between groups were comparable at 15 cm H₂O PCV (p=0.495, p=0.104) but not at 20 and 25 H₂O PCV (p<0.001, p<0.001). Pharyngolaryngeal morbidity was significantly lesser in the i-gel group.

Conclusion

I-gel provides a reasonable alternative to cuffed ETT for pressure-controlled ventilation provided the pressures can be limited to 15 to 20 cm H₂O.

Removal of Laryngeal Mask Airway in Adults Under Target-Controlled, Propofol-Fentanyl Infusion Anesthesia: Awake or Deep Anesthesia?

After emergence from anesthesia, the incidence and severity of adverse airway effects caused by the laryngeal mask airway (LMA) can vary, depending on when the device was removed; nonetheless, reports differ regarding the exact optimal timing of LMA removal. The purpose of this study was to compare the rate of adverse events between 2 groups: those whose LMA was removed under general anesthesia ("deep" group) or under target-controlled infusion (TCI) of propofol ("awake" group).Institutional Review Board approval and written informed consent were obtained; 124 patients were then randomly allocated into either the "awake" group or the "deep" group. Anesthesia was induced and maintained using TCI of propofol, as well as intravenous fentanyl. In the "deep" group, the LMA was removed after surgery while the patients were deeply anesthetized using a target effect-site propofol concentration of 2 μg/mL, whereas in the "awake" group, the device was removed while the patients followed verbal instructions. The incidence of the following adverse events was recorded: coughing, straining, bronchospasm, laryngospasm, clenching, breath holding, gross purposeful movement, airway obstruction, retching, vomiting, and oxygen desaturation. If any such event occurred, the LMA removal was considered a failure. Airway hyperreactivity was recorded and graded - based on the severity of cough, breath holding, and oxygen desaturation.The failure rate was higher in the "awake" group (15/61; 24.6%) than in the "deep" group (5/60; 8.3%). Airway hyperreactivity was mild (score, <3) in both groups.Removal of the LMA under deep anesthesia using a target-controlled, effect-site propofol concentration of 2 μg/mL may be safer and more successful than removal when patients are fully awake after surgery.

Comparison of I-gel with proseal LMA in adult patients undergoing elective surgical procedures under general anesthesia without paralysis: A prospective randomized study

Background:

We compared i-gel and ProSeal laryngeal mask airway (PLMA) regarding time taken for insertion, effective seal, fiberoptic view of larynx, ease of Ryle's tube insertion, and postoperative sore throat assessment.

Materials and Methods:

In a prospective, randomized manner, 48 adult patients of American Society of Anesthesiologists I-II of either gender between 18 and 60 years presenting for a short surgical procedure were assigned to undergo surgery under general anesthesia on spontaneous ventilation using either the i-gel or PLMA. An experienced nonblinded anesthesiologist inserted appropriate sized i-gel or PLMA in patients using standard insertion technique and assessed the intraoperative findings of the study regarding regarding time taken for respective device insertion, effective seal, fiberoptic view of larynx, ease of Ryle's tube insertion, and postoperative sore throat assessment. Postoperative assessment of sore throat was done by blinded anesthesia resident.

Results:

The time required for insertion of i-gel was lesser (21.98 ± 5.42 and 30.60 ± 8.51 s in Group I and Group P, respectively; P = 0.001). Numbers of attempts for successful insertions were comparable and in majority, device was inserted in first attempt. The mean airway leak pressures were comparable. However, there were more number of patients in Group P who had airway leak pressure >20 cm H₂O. The fiberoptic view of glottis, ease of Ryle's tube insertion, and incidence of complications were comparable.

Conclusion:

Time required for successful insertion of i-gel was less in adult patients undergoing short surgical procedure under general anesthesia on spontaneous ventilation. Patients with airway leak pressure >20 cm H₂O were more in PLMA group which indicates its better suitability for controlled ventilation.

Laryngeal mask airways have a lower risk of airway complications compared with endotracheal intubation: a systematic review

PURPOSE

The purpose of the present study was to determine whether, in patients undergoing general anesthesia, those provided with a laryngeal mask airway (LMA) have a lower risk of airway-related complications than those undergoing endotracheal intubation.

MATERIALS AND METHODS

A systematic review of randomized prospective controlled trials was done to compare the risk of airway complications with an LMA versus an endotracheal tube (ETT) in patients receiving general anesthesia. Two independent reviewers identified 29 randomized prospective controlled trials that met the predetermined inclusion and exclusion criteria. The data for each individual outcome measure were combined to analyze the relative risk ratios (RRs). The Cochrane RevMan software was used for statistical analysis.

RESULTS

When an ETT was used to protect the airway, a statistically significant greater incidence of hoarse voice (RR 2.59, 95% confidence interval [CI] 1.55 to 4.34), a greater incidence of laryngospasm during emergence (RR 3.16, 95% CI 1.38 to 7.21), a greater incidence of coughing (RR 7.12, 95% CI 4.28 to 11.84), and a greater incidence of sore throat (RR 1.67, 95% CI 1.33 to 2.11) was found compared with when an LMA was used to protect the airway. The differences in the risk of regurgitation (RR 0.84, 95% CI 0.27 to 2.59), vomiting (RR 1.56, 95% CI 0.74 to 3.26), nausea (RR 1.59, 95% CI 0.91 to 2.78), and the success of insertion on the first attempt (RR 1.08, 95% CI 0.99 to 1.18) were not statistically significant between the 2 groups.

CONCLUSIONS

For the patients receiving general anesthesia, the use of the LMA resulted in a statistically and clinically significant lower incidence of laryngospasm during emergence, postoperative hoarse voice, and coughing than when using an ETT. The risk of aspiration could not be determined because only 1 study reported a single case of aspiration, which was in the group using the ETT.

Comparison of the i-gel with the cuffed tracheal tube during pressure-controlled ventilation

BACKGROUND

The i-gel (Intersurgical Ltd) is a novel device that differs from other supraglottic airway devices in that it has a softer and a non-inflatable cuff. Our study was designed to assess whether the i-gel is suitable to provide pressure-controlled ventilation (PCV) during anaesthesia by measuring the gas leaks and comparing these values with that of the tracheal tube.

METHODS

Twenty-five patients, ASA I-II, were recruited to the study. Patients received a standard anaesthetic technique followed by an initial placement of the i-gel. The lungs were then ventilated at three different pressures (15, 20, 25 cm H(2)O) using PCV. The difference between the inspired and expired tidal volumes was used to calculate the leak volume. The leak fraction was defined as the leak volume divided by the inspired tidal volume. Following these observations, the i-gel was removed and replaced with the conventional tracheal tube and the recordings repeated.

RESULTS

There was no significant difference between the leak fractions of the i-gel and the tracheal tube at 15 and 20 cm H(2)O PCV. At 25 cm H(2)O, the median difference in leak fraction was 0.02 (P=0.014) and the median difference in leak volume was 26.5 ml (P=0.006). There was no evidence of gastric insufflations with any of the pressures used during PCV.

CONCLUSIONS

We suggest that the i-gel can be used as a reasonable alternative to tracheal tube during PCV with moderate airway pressures.

Anaesthesia in endoscopic sinus surgery

The aim of this study was to evaluate the methods of anaesthesia used in 1,460 patients (677 females and 783 males), aged 4 to 79 years, who were consecutively operated on with a functional endonasal endoscopic approach (FESS) or by an endoscopic endonasal approach (ESS) by one surgeon (AD) in the period from 1987-2001. The included patients presented a variety of disorders within the nose and sinuses. Many of the patients had sinonasal polypoid disease, which had gradually expanded over years and was causing pressure to neighbouring structures. Several had undergone previous multiple surgical procedures altering the original anatomy. However, the majority of the patients had been treated surgically for acute recurrent and/or chronic infections, others for sinogenic headache, benign tumours/mucoceles and smell disorders. The intention of looking into the anaesthetic procedures being used was to clarify the needs for a differentiated anaesthetic approach to different surgical tasks. It is of crucial importance for an optimal surgical result that both the patient and surgeon feel absolutely comfortable during the operation. Local anaesthesia can be used in minor surgery on selected patients and is definitely suitable even for residents in training. General anaesthesia is preferred in most cases by both patients and surgeons. The conclusion of this paper is that total intravenous anaesthesia (TIVA) in addition to oxygen-enriched air through a laryngeal mask airway (LMA) should be the anaesthetic procedure of choice, at least in our experience.

Hemodynamic and catecholamine response to tracheal intubation: direct laryngoscopy compared with fiberoptic intubation

STUDY OBJECTIVE

To compare the stress response following tracheal intubation using direct laryngoscopy to that using fiberoptic bronchoscopy technique.

DESIGN

Randomized, prospective study.

SETTING

Operating rooms in a teaching hospital.

PATIENTS

51 ASA physical status I and II patients who were scheduled for an elective surgery with general anesthesia.

INTERVENTIONS

Patients were randomly assigned to receive either direct laryngoscopy or fiberoptic orotracheal intubation, as part of general anesthesia. A uniform protocol of anesthetic medications was used.

MEASUREMENTS

Blood pressure and heart rate were measured before induction, before endotracheal intubation, and 1, 2, 3, and 5 minutes afterwards. Catecholamine (epinephrine and norepinephrine) blood samples were drawn before the induction, and 1 and 5 minutes after intubation.

MAIN RESULTS

Duration of intubation was shorter in the direct laryngoscopy group (16.9 (16.9 +/- 7.0 sec, range 8 to 40) compared with the fiberoptic intubation group (55.0 +/- 22.5 sec, range 29 to 120), p < 0.0,001. In both groups, blood pressure and heart rate were significantly increased at 1, 2, and 3 minutes after intubation, but there was no significant difference between the two study groups. Catecholamine levels did not increase after intubation and did not correlate with the hemodynamic changes.

CONCLUSIONS

The use of either direct laryngoscopy or fiberoptic bronchoscopy produces a comparable stress response to tracheal intubation. Catecholamine levels do not correlate with the hemodynamic changes.

Gum-elastic bougie-guided insertion of the ProSeal laryngeal mask airway: a new technique

We determined the success rates, cardiovascular responses and airway morbidity for gum-elastic bougie-guided insertion of the ProSeal laryngeal mask airway. One hundred anaesthetized, non-paralyzed adults (ASA 1-2 aged 18 to 80 years) were studied. The ProSeal LMA drainage tube was primed with a well-lubricated 16 French gauge gum-elastic bougie with the curved end proximal and the straight end protruding 30 cm beyond the drainage tube tip. The straight end of the gum-elastic bougie was inserted into the oesophagus under laryngoscopic guidance, the laryngoscope removed and the ProSeal LMA inserted using the standard insertion technique and the gum-elastic bougie as a guide. The following variables were recorded: ease of insertion, oropharyngeal leak pressure, ventilatory capability, ease of gastric tube insertion, blood staining on the bougie or LMA at removal, and postoperative airway morbidity. Haemodynamic data were recorded immediately pre-insertion and every minute for five minutes after insertion. Gum-elastic bougie and ProSeal LMA insertion was successful at the first attempt in all patients within 50 seconds. There were no significant increases in heart rate or blood pressure. Oropharyngeal leak pressure was 33 (17-40) cmH2O and ventilation was possible without leak in all patients at 9.5 ml x kg(-1) tidal volume. There were no drainage tube or gastric air leaks. Gastric tube insertion was successful at the first attempt in all patients. Blood staining at removal was not detected on the gum-elastic bougie, but was detected in 3% of ProSeal LMAs. The incidence of sore throat, dysphagia and dysarthria was 21%, 9% and 1% respectively. We conclude that gum-elastic bougie-guided insertion of the ProSeal LMA has a high success rate and is associated with minimal haemodynamic change and a low incidence of trauma.

Total intravenous anesthesia for office-based laser facial resurfacing

BACKGROUND AND OBJECTIVE

Providing general anesthesia in an office-based setting can be time consuming, risky, and expensive. The purpose of this study was to describe a technique for total intravenous anesthesia (TIVA) technique that can be easily utilized by anesthesiologists in an office-based setting for laser facial resurfacing.

STUDY DESIGN/MATERIALS AND METHODS

Twenty-five American Society of Anesthesiologists (ASA) status classification I-II patients (22 females and three males) elected general anesthesia for laser facial resurfacing. All patients were premedicated with glycopyrrolate (0.2 mg IV). All anesthetics were administered by board-certified anesthesiologists, and ASA Standards for Anesthesia Monitoring were strictly followed. An induction dose of propofol (2. 0-2.5 mg/kg IV) was followed by laryngeal mask airway insertion (size 3 or 4). TIVA was maintained with a propofol infusion (50-250 mcg/kg/minute IV). Supplemental midazolam (2-4 mg IV), fentanyl (0. 05-0.20 mg IV), and oxygen (2-4 l/minute) were administered as needed. After completion of the laser procedure, TIVA was discontinued and the patients were allowed to awaken. Patients were discharged after achieving a Modified Post-Anesthetic Discharge Score of >/= 9.

RESULTS

Mean procedure duration was 48 +/- 21 minutes, and time to discharge after the procedure was 16 +/-6 minutes. All procedures and anesthetics were well tolerated and without complications. The only post-procedure complaint was an isolated, minor, and temporary sore throat.

CONCLUSIONS

TIVA is an excellent method for providing anesthesia for laser facial resurfacing in an office-based setting.

Variation of nitric oxide concentration during inspiration

OBJECTIVE

To evaluate the pattern of inspiratory nitric oxide concentration in a simple, constant flow delivery system during the use of two phasic-flow ventilatory modes.

DESIGN

Laboratory study in a lung model.

SETTING

University experimental laboratory.

SUBJECT

Nitric oxide (800 ppm in nitrogen) was administered continuously into the inspiratory circuit to deliver a nitric oxide concentration of 10 and 40 ppm to a test lung during volume-controlled (constant flow) and pressure-controlled (decelerating flow) ventilation, with an FIO2 of 1.0.

INTERVENTIONS

In each mode, minute ventilation of 7, 14, and 21 L/min and installation of mixing chambers (none, 1-L, 2-L, and 3.2-L turbulence boxes) were studied, respectively. Nitric oxide and nitric dioxide were monitored by chemiluminescence. Since the nitric oxide/nitrogen gas is the only nitrogen source in the system during ventilation with an FIO2 of 1.0, we evaluated the fluctuation in the inspiratory nitric oxide (NOx) concentration by measuring nitrogen with a fast-response analyzer. To test the effect of the measurement site, we measured nitric oxide concentrations using chemiluminescence at different positions in the inspiratory and expiratory limbs, with and without the mixing chambers, with a minute ventilation of 14 L/min and a nitric oxide concentration of 40 ppm.

MEASUREMENTS AND MAIN RESULTS

Nitrogen dioxide production was not influenced by the flow pattern. During a nitric oxide concentration of 10 ppm, nitrogen dioxide was always < 0.6 ppm. During a nitric oxide concentration of 40 ppm, the highest nitrogen dioxide (4.47 ppm) concentration was found at the lowest minute ventilation and the largest inspiratory circuit volume. Nitric oxide values displayed by chemiluminescence indicated stable concentrations at all settings. However, without mixing chambers, NOx concentration calculated from nitrogen measurements demonstrated marked inspiratory fluctuations and was highest with a minute ventilation of 21 L/min and higher during pressure-controlled ventilation compared with volume-controlled ventilation (nitric oxide concentration of 40 ppm, pressure-controlled ventilation: 14.5 to 130.5 ppm; volume-controlled ventilation: 21.6 to 104.7 ppm; nitric oxide concentration of 10 ppm, pressure-controlled ventilation: 3.2 to 30.9 ppm; volume-controlled ventilation: 4.5 to 27.1 ppm). NOx concentration fluctuation decreased with an increasing mixing chamber, and was negligible at all settings with the 3.2-L turbulence box. Nitric oxide concentration fluctuation influenced chemiluminescence measurements. The displayed nitric oxide values varied, depending on the sampling site, and did not accurately reflect mean inspiratory nitric oxide concentration. Incorporation of a mixing chamber eradicated this sampling site influence.

CONCLUSIONS

Continuous flow delivery of nitric oxide into the circuit of a phasic-flow ventilator results in marked inspiratory nitric oxide concentration fluctuation that is not detected by a slow-response chemiluminescence analyzer. Moreover, nitric oxide concentration fluctuation can influence the accuracy of the chemiluminescence measurements. These effects can be diminished by using additional mixing chambers to facilitate a stable gas concentration. As these mixing volumes increase the contact time of nitric oxide with oxygen, an increase of nitrogen dioxide has to be taken into account.