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Indian J Otolaryngol Head Neck Surg. 2023 Mar; 75(1): 32–38.
Published online 2022 Aug 18. doi:10.1007/s12070-022-03099-w
PMCID: PMC10050500
PMID: 37007892
Ying Wan,#1 Ying Liu,#1 Chunhua Xi,2 Xu Cui,2 and Guyan Wang
2
Author information Article notes Copyright and License information PMC Disclaimer
Abstract
To investigate the effect of two-step of jaw-thrust technique on the placement of flexible laryngeal mask with both hands. 157 patients scheduled for functional endoscopic sinus surgery were divided into two groups using a random number table method: control group (group C, n = 78) and test group (group T, n = 79). After induction of general anesthesia, the traditional method was applied to insert the flexible laryngeal airway mask in group C, and the two-step of jaw-thrust technique with both hands by the nurse was applied to help place the laryngeal mask in group T. The success rate, alignment status, oropharyngeal leak pressure (OLP) of the laryngeal mask, soft tissue injury of the oropharyngeal cavity and postoperative sore throat, and the incidence of adverse airway event were recorded in both groups. Results: The success rate of the first placement of flexible laryngeal masks in group C and group T were 73.8% and 97.5%, and the final success rates were 97.5% and 98.7%, respectively. Compared with group C, the success rate of first placement in group T was higher, and the difference was statistically significant (P < 0.01). There was no significant difference in the final success rate between the two groups (P = 0.56). The alignment score showed that the placement of group T was better than that of group C, and the difference was statistically significant (P < 0.01). The OLP of group C was 22.1 ± 2.6 cmH2O, and the OLP of group T was 25.4 ± 3.8 cmH2O. The OLP of group T was significantly higher than that of group C (P < 0.01). The incidence of mucosal injury and postoperative sore throat in group T were 2.5% and 5.0%, which were significantly lower than that of 23.0% and 16.7% in group C (both P < 0.01). There was no adverse airway event in each group. Conclusion: The two-step of jaw-thrust technique with both hands can improve the success rate of the first placement of the flexible laryngeal mask and the positioning of the laryngeal mask, increase the sealing pressure of the laryngeal mask, and reduce the incidence of oropharyngeal soft tissue injury and postoperative pharyngeal pain.
Keywords: Flexible laryngeal mask, Traditional technique, Two-step of jaw-thrust technique with both hands, Oropharyngeal leak pressure, Sore throat
Introduction
Flexible laryngeal mask (FLMA) has more advantages in general anesthesia in facial features. Its simple operation can reduce hemodynamic fluctuations during intubation, reduce adverse airway events during extubation and speed up surgery Turnover. Compared with the classic laryngeal mask, the flexible laryngeal mask has a longer catheter end and can be far away from the operation area. The tube can be bent and resistant to compression. It is not easy to move when the head and neck are turned, which is convenient for the operator to operate [1, 2]. Well-positioned FLMA can provide a suitable oropharyngeal sealing pressure, fully protect the glottis and lower airway from blood and surgical irrigation fluid contamination [3, 4]. However, the long and flexible catheter is not conducive to the transmission of force, and it is prone to rotation and misalignment during traditional single placement. Therefore, the success rate of ventilation with a flexible laryngeal mask is slightly lower than that of a classic laryngeal mask [5, 6]. The purpose of this study is to compare the effect of traditional laryngeal mask placement method and two-step of jaw-thrust technique, which is participated by itinerant nurses, on the success rate, contraposition, closed pressure of laryngeal mask, soft tissue injury of oropharyngeal cavity and postoperative pharyngeal pain in adults under general anesthesia. This study also explores to improve the conditions of laryngeal mask placement.
Materials and Methods
Normal Information
A total of 157 patients, aged 18–65years old, under the American Society of Anesthesiologists (ASA) grade I–II, who were scheduled to undergo elective endoscopic sinus in our hospital from September 2019 to January 2020, were selected. The estimated operation time is within 4h. Exclusion criteria: patients with contraindications for the use of laryngeal masks; patients with mouth opening less than 2.5cm; severely obese patients with body mass index (BMI) greater than 35. Random number table method was used to divide patients into control group (C group) and experimental group (T group), 78 cases in Control (C) group and 79 cases in Test (T) group. This study was approved by the ethics committee of Beijing Tongren Hospital affiliated to Capital Medical University (Ethics Number: TRECKY2016-020), and signed an informed consent form with the patient.
Anesthesia Method
All patients were strictly prohibited from drinking water before operation. After entering the room, the vein was opened and blood pressure, heart rate, pulse oxygen saturation and end-expiratory carbon dioxide (ETCO2) were monitored. After oxygen is given and nitrogen is exhausted through mask, Atropine 0.5mg, midazolam 0.03mg/kg, cisatracurium 0.15mg/kg, sufentanil 0.2g/kg and propofol 1.5–2mg/kg were intravenously administered. After patients'consciousness disappeared and muscle relaxation was improved, the appropriate model of flexible laryngeal mask (disposable use of laryngeal mask airway catheter, Tianjin Medidis Medical Products Co., Ltd., China) was placed in the patient's oropharynx after applying Obucaine gel on the tip and back. The laryngeal mask is placed by an experienced anesthetist who has worked for more than 3years, and the model of the flexible laryngeal mask is selected according to the patient's weight: the body weight ≥ 70kg uses the No. 5 laryngeal mask, the body weight < 50kg uses the No. 3 laryngeal mask, and the rest use a No. 4 laryngeal mask. After three failed trials of laryngeal mask ventilation, it was changed to tracheal intubation. Anesthesia was maintained by intravenous injection of propofol 6–8mg/kg/h and remifentanil 0.1–0.2μg/kg/min, intermittent injection of cisatracurium 0.05mg/kg. During the operation, pure oxygen was inhaled, positive pressure ventilation was used, the tidal volume was 6–8ml/kg, the inspiratory-expiratory ratio was 1:2, and the respiration frequency was adjusted make ETCO2 keep 35–40mmHg. After the operation, the blood and secretions in the mouth were sucked fully, and the laryngeal mask was pulled out after the patient was fully awake, and the patient was sent to the anesthesia recovery room (PACU) for observation. Before leaving the PACU, the patient was scored by visual simulation method (VAS, 0–10 points), and a score greater than 3 was defined as the occurrence of throat pain.
Method and Positioning of Laryngeal Mask Placement
Group C was treated with traditional FLMA placement. The patient was placed in a backward position with his head. The anesthesiologist opened his mouth with his left hand, lifted his jaw with his thumb, and placed his right index finger between the laryngeal mask bag and the ventilation tube. The anesthesiologist place along the posterior wall of the oropharynx from the median approach until there was significant resistance in the pharynx. Group T: A nurse standing on the right shoulder side of the patient, holding the mandibular angle of the patient while holding the patient's head back with both hands, and opening the patient's mouth as far as possible with both thumbs backward and downward. At same time, the anesthesiologist fixes the top of the patient's head with his left hand, and puts the laryngeal mask body into the mouth cavity with his right hand; while holding the mandibular angle, the tour nurse lifts the mandibular angle upward, opens the pharyngeal cavity. Then, while holding the mandibular angle, the nurse lifted the mandibular angle upward to open the pharyngeal cavity. The anesthetist placed the laryngeal mask along the posterior pharyngeal wall with the index finger of his right hand. When opening the pharyngeal cavity while lifting the mandibular angle, it is necessary to keep the mouth open to prevent accidental injury to the fingers of the anesthesiologist after lifting the posterior teeth of the mandible. See Fig.1 for operation. After the two groups of laryngeal masks were inserted, the cuff pressure was inflated to 60mmHg, then the laryngeal mask and the anesthesia machine line were connected, and manual control breathing was performed to judge the position of the laryngeal mask: (1) Observe the effectiveness of ventilation: When the tidal volume is controlled at 6ml/kg, auscultate the neck for murmurs and observe the peak airway pressure. If there is no murmur and the peak airway pressure is less than 20cm H2O, continue to measure the maximum air leakage pressure. Otherwise, it is considered as the failure of laryngeal mask placement and need to be replaced. (2) oropharyngeal leak pressure (OLP): Close the valve of the anesthesia machine, and the flow rate of fresh gas is 5L/min. Observe the rise of airway pressure in the curve of the respiratory volume loop. When the peak airway pressure in the curve no longer rises or there is a leak in the mouth, the airway pressure at this time is OLP. (3) Positional scoring of fiber laryngoscope (FOB): 1 score was only seen in the larynx, 2 score was visible vocal cords and posterior epiglottis, 3 score was visible in the larynx and epiglottis overlapped on the fence of the laryngeal mask, 4 score was epiglottis prolapse, larynx was not visible. (4) Pharyngeal injury: fiber laryngoscope was placed through the oral cavity to observe whether there was mucosal injury and bleeding in the way of laryngeal mask placement.
Fig. 1
The process of opening the oral cavity (a), placing the laryngeal mask into the oral cavity (b), and placing the laryngeal mask into the pharyngeal cavity (c) and the alignment effect of x fiber laryngoscope (d); Opening the oral cavity (e), placing the laryngeal mask into the oral cavity (f), and placing the laryngeal mask into the pharyngeal cavity (g)
Observation Index
General conditions such as gender, age, height, weight, type of laryngeal mask used and operation time were recorded. The baseline status, mean arterial pressure (MAP) and heart rate (HR) were recorded 1min before and 1min after laryngeal mask placement in both groups. The one-time success rate and final success rate of laryngeal mask placement, the corresponding scores of OLP and FOB after placement, the complications related to laryngeal mask such as pharyngeal injury and pharyngalgia were recorded in both groups. Airway adverse events during anesthesia and during recovery, including reflux aspiration, bronchospasm, laryngospasm, hypoxemia (oxygen saturation below 91% lasting more than 1min) were recorded.
Statistical Methods
SPSS 23.0 was used for statistical analysis. Normally distributed measurement data were expressed as mean ± and standard deviation expressed as (x ± s). Two-sample independent t-test was used for measurement data between groups, rank-sum test was used for rank data, and chi-square test was used for counting data. P < 0.05 was statistically significant.
Results
General Situation Comparison
As shown in Table Table1,1, there was no significant difference between the two groups in general conditions such as gender, age, height, weight, BMI, operation time and the proportion of different types of laryngeal mask used (P > 0.05), which was comparable.
Table 1
Comparison of general data of two groups of patients
| Group | Gender (male/female) | Age (Year) | Height (cm) | Weight (kg) | BMI (kg/m2) | Operation time (min) | Mask type (4#/5#, n) |
|---|---|---|---|---|---|---|---|
| C (n = 78) | 45/35 | 41.0 ± 13.7 | 167.6 ± 8.8 | 69.8 ± 14.0 | 24.6 ± 4.0 | 83.2 ± 28.5 | 57/21 |
| T (n = 79) | 48/32 | 39.5 ± 15.1 | 169.1 ± 8.7 | 67.7 ± 13.8 | 23.6 ± 3.3 | 78.7 ± 27.2 | 59/20 |
| t/χ2 value | 0.23 | 0.70 | 1.06 | 0.95 | 1.79 | 1.02 | 0.05 |
| P value | 0.63 | 0.49 | 0.29 | 0.35 | 0.08 | 0.31 | 0.81 |
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Operating Procedure of Two-Step of Jaw-Thrust Technique by Both Hands
As shown in Fig.1, two-step of jaw-thrust technique by both hands was used in the operation, which was divided into the following steps (Fig. (Fig.22).
Fig. 2
The basic state of the two groups and the hemodynamic changes before and after implantation of the laryngeal mask
Hemodynamic Changes
There were no significant differences in basal blood pressure, heart rate and changes of blood pressure and heart rate before and after laryngeal mask placement between the two groups (all P > 0.05, Table Table22).
Table 2
Basic state and hemodynamic changes before and after laryngeal mask placement in two groups
| Group | Basic state | Before 1min | After 1min | |||
|---|---|---|---|---|---|---|
| Blood pressure (mmHg) | Heart rate (Time/min) | Blood pressure (mmHg) | Heart rate (Time/min) | Blood pressure (mmHg) | Heart rate (Time/min) | |
| C (n = 78) | 94.0 ± 8.1 | 76.2 ± 9.6 | 74.3 ± 9.4 | 67.4 ± 10.7 | 74.9 ± 8.6 | 66.6 ± 10.4 |
| T (n = 79) | 91.8 ± 11.2 | 76.6 ± 10.1 | 75.0 ± 10.0 | 68.5 ± 10.1 | 74.5 ± 9.0 | 68.4 ± 11.5 |
| t/χ2 value | 1.12 | 0.20 | 0.33 | 0.55 | 0.21 | 0.82 |
| P value | 0.26 | 0.83 | 0.74 | 0.58 | 0.83 | 0.41 |
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Success Rate, Alignment and OLP Comparison of Laryngeal Mask Placement
The first successful rate of laryngeal mask placement in group T was higher than that in group C, and the difference was statistically significant (P < 0.01); 1 case in group T and 2 cases in group C were changed to endotracheal intubation because of three times of failed laryngeal mask placement, and the rest were successfully ventilated by laryngeal mask. There was no significant difference in the final successful rate of laryngeal mask placement between the two groups (P = 0.56); no leakage or displacement of laryngeal mask occurred in both groups during operation. FOB position score showed that T group was superior to C group, and the difference was statistically significant (P < 0.01). OLP in group T was higher than that in group C, and the difference was statistically significant (P < 0.01), as shown in Table Table33.
Table 3
Comparison of success rate, alignment, airtight pressure, oropharyngeal injury and postoperative pharyngalgia between the two groups
| Group | First-time success rate (%) | Final success rate N (%) | FOB position score (1/2/3/4), n | Air leakage pressure (cmH2O) |
|---|---|---|---|---|
| C (n = 78) | 59 (73.8) | 78 (97.5) | 41/33/2/2 | 22.1 ± 2.6 |
| T (n = 79) | 78 97.5) | 79 (98.8) | 58/19/3/1 | 25.4 ± 3.8 |
| t/χ2 value | 18.33 | 0.34 | 111.1 | 4.51 |
| P value | < 0.01 | 0.56 | < 0.01 | < 0.01 |
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Comparisons of Complications Between the Two Groups
As shown in Table Table44 and Fig.3, the incidence of mucosal injury and postoperative pharyngalgia in group T was significantly lower than that in group C, and the difference was statistically significant (P < 0.01). There were 3 cases of soft palate injury, 1 case of palatal arch injury, 14 cases of posterior oropharyngeal wall abrasion, and 13 cases of postoperative pharyngalgia in group C. In group T, there were 2 cases of abrasion on the posterior wall of oropharynx and 4 cases of postoperative pharyngalgia. No airway adverse events such as reflux aspiration, bronchospasm, laryngeal spasm, and hypoxemia occurred during anesthesia and recovery phase.
Table 4
Complications of two groups of patients
| Group | Soft palate injury (n) | Palatal arch injury (n) | Oropharyngeal wall abrasion (n) | Postoperative pharyngalgia (n) |
|---|---|---|---|---|
| C | 3 | 1 | 14 | 13 |
| T | 0 | 0 | 2 | 4 |
| χ2 value | 14.6 | 5.47 | ||
| P value | < 0.01 | 0.02 | ||
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Fig. 3
Complications comparison between two groups
Discussion
The traditional method of bendable laryngeal mask placement is that the anesthesiologist carries the mandible with his left hand and pushes the index finger through the median approach with his right hand while keeping the patient's head back [7, 8].However, the operation success rate is lower than other types of laryngeal masks, mainly because a single person cannot fix the head, it is difficult to keep the patient's head back; lack of laryngoscope support, it is difficult to ensure satisfactory mouth opening; soft catheters have no support force, and cannot overcome resistance. In recent years, there have been many improved methods for the placement of bendable laryngeal masks, such as the 90-degree rotation method and the addition of laryngeal mask guides [9, 10]. However, the operation is complicated, the stimulation is great, and the clinical is not popular. In addition, repeated insertion of the laryngeal mask and the violent operation can cause soft tissue damage in the oropharynx, increasing the incidence of postoperative sore throat [11]. In this study, it was found that the two-step of jaw-thrust technique by both hands had little stimulation and had no significant effect on hemodynamics. The success rate of the first intubation with a flexible laryngeal mask can be improved by two-handed approach, which is consistent with previous reports of mandibular support assisted by anesthetic nurses [12]. When the anesthesiologist placed the laryngeal mask on the head side of the patient with a backward position, the right hand operated downward and forcefully toward the foot side in the oral cavity, and it was difficult to maintain the head in the backward position. The three-dimensional finite element model reconstructed by NMR found that the minimum cross-sectional area of the upper airway was larger in the head-back supine position than in the supine position, whether in normal or difficult airways [13]. Clinical studies have also found that hyperextension of the head can elevate the hyoid bone and laryngeal inlet, increase the anterior and posterior diameters of the pharyngeal space, and flexion of the head can lead to a decrease in the anterior and posterior diameters of the pharyngeal cavity, even partial airway obstruction [14, 15] Therefore, the maximum volume of the pharyngeal cavity can be ensured during the placement of the laryngeal mask with the fixed head in the backward position, which is conducive to the smooth placement of the laryngeal mask [16, 17]. Itinerant nurses use their thumbs to open the oral cavity forcefully, which is helpful for the anesthetist to smoothly place the mask body along the midline, and it is not easy for the laryngeal mask to rotate and discount. Supporting the mandibular angle and lifting the mandible at the same time is beneficial to fully open the pharyngeal cavity and increase the space within the pharyngeal cavity, so that the tongue surface of the laryngeal mask can be smoothly laid on the mucosa of the pharyngeal cavity and placed down smoothly along the posterior pharyngeal wall [18, 19]. Putting it close to the posterior wall of the pharynx on one hand can avoid the occurrence of air leakage caused by wrinkles on the tongue surface of the laryngeal mask. On the other hand, it can ensure that the tip of the mask is located at the entrance of the esophagus, rather than the tip of the mask rising upward to block the entrance of the glottis. The observation results showed that the laryngeal mask was better positioned and the sealing pressure was higher. During nasal endoscopic surgery, blood, fluids, secretions, etc. will flow into the pharynx. The higher the airtight pressure is, the higher the safety is.
It is worth noting that the incidence of pharyngeal cavity injury and pharyngalgia in group T was significantly lower than that in group C in this study. We found that soft palate injury in group C resulted in nasopharyngeal hemorrhage and palatal arch injury, which were associated with greater resistance, repeated placement and violent manipulation [20–22]. One patient with palatal arch injury presented with persistent severe pharyngalgia after surgery, requiring additional antibiotics and aerosol therapy. The T group all had slight posterior pharyngeal wall abrasion, which may be related to the high success rate of the first insertion and no obvious resistance to catheterization. Therefore, improving the method of laryngeal mask placement can increase the success rate of laryngeal mask placement for the first time to avoid severe soft tissue injury and postoperative sore throat.
In summary, two-step of jaw-thrust technique by both hands can increase the success rate of the first placement of the flexible laryngeal mask, improve the positioning of the laryngeal mask and increase the sealing pressure of the laryngeal mask, and reduce the incidence of oropharyngeal soft tissue injury and postoperative sore throat. Its operation is simple and easy, and it is worthy of widespread promotion in clinic.
Footnotes
Publisher's Note
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Ying Wan and Ying Liu contribute equal to this article as co-first author.
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