Background: The application of bedside ultrasound to evaluate gastric content and volume can assist in determining aspiration risk. Applying positive pressure ventilation via supraglottic airway devices (SAD) can result in a degree of gastric insufflation. This study assessed and compared the antral cross-sectional area (CSA) in patients undergoing laparoscopic gynecological surgery when managed with different SAD. Methods: One hundred American Society of Anesthesiologists I or II female patients were assessed for inclusion in this study and divided into three groups of different ventilation devices. Patients were randomly allocated into three groups to receive LMA-Supreme (Group S), I-gel (Group I) or tracheal tube (Group T). The primary outcome was the antral cross-sectional area and secondary outcomes included haemodynamic parameters and postoperative morbidity such as sore throat, hoarseness, dry throat, nausea and vomiting. Results: The antral CSA was not significantly different among three groups before induction (P = 0.451), after induction (P = 0.456) and at the end of surgery (P = 0.195). The haemodynamic variables were significantly higher in the tracheal tube group than in the LMA-Supreme and I-gel groups after insertion (P < 0.0001) and after removal (P < 0.01). Sore throat was detected in none in the I-gel group compare to two patients (6.7%) in the LMA-Supreme group and fifteen patients (50%) in the tracheal tube group. Hoareness was detected in one (3.3%) in the I-gel group compare to two patients (6.7%) in the LMA-Supreme group and eleven patients (36.7%) in the tracheal tube group. Conclusions: The SADs do not cause obvious gastric insufflation. Thus, LMA-Supreme and I-gel can be widely used as alternative to endotracheal intubation for the short laparoscopic gynecological surgery. Trial registration: This trial was registered at the Chinese Clinical Trial Registry (ChiCTR1800018212, data of registration, September 2018).
Keywords: Supraglottic airway devices; Ultrasound; Gastric insufflation; Laparoscopic
Qiuping Ye and Di Wu contributed equally to this work.
Perioperative aspiration of gastric content is a rare but serious anesthetic-related complication which may result in significant morbidity and mortality [[
Gastric ultrasound is an emerging point-of-care procedure that has been used to evaluate gastric content and volume in the assessment of perioperative aspiration risk [[
This trial was conducted at the First Affiliated Hospital of Anhui Medical University between September 2018 and March 2019. Patients were prospectively randomized into one of three-group. This trial was registered at the Chinese Clinical Trial Registry (ChiCTR1800018212) on September 5, 2018, and was approved by Institutional Ethics Committee (The First Affiliated Hospital of Anhui Medical University Ethics Committee, PJ2016-08-06, Anhui, China). This study adheres to CONSORT guidelines. Informed consent was obtained from 100 ASA physical status I and II female patients patients aged 18 years or more scheduled to undergo elective laparoscopic gynecological surgery lasting less than 3 h were recruited with ninety patients completing the protocol. We excluded those with preoperative sore throat and / or hoarseness, known risk factors for gastric aspiration, a BMI of 35 or more, Mallampati grade III or 4 and had facial and upper airway abnormalities that would make mask ventilation or tracheal intubation difficult. One patient was excluded because her surgery was canceled. The remaining 99 patients were allocated into three groups (Group S, Group I, Group T) to receive airway management with LMA Supreme, I-gel or tracheal tube respectively, following a computer-generated randomization code.
After arrival in the operating room, all enrolled patients were premedicated with intravenous midazolam 2 mg and standard monitoring (noninvasive assessment of blood pressure, oxygen saturation, pulse oximetry, electrocardiography) was applied. After preoxgenation, patients were induced with etomidate 0.2–0.3 mg/kg, sufentanil 0.5–0.7μg/kg and cis-atracurium 0.2–0.3 mg/kg. Upon the disappearance of the eye lash reflex, the same anesthesiologist applied jaw thrust with the head neutral position. Patients were mask ventilated for 2 min using the Fabius anesthesia machine (Drager, Germany). Controlled ventilation was set to a tidal volume of 8 mLkg
Anesthesia was maintained with propofol 4–8 mg/kg·h
Antral cross-sectional area (CSA) was the primary observed parameter. The stomach was imaged with patient in the supine position by using the low-frequency (2-5 MHz) curved array transducer of a sono ultrasound (FUJIFLIM SonoSite Inc. USA) machine. The antrum was located superficially between the left lobe of the liver anteriorly and the pancreas posteriorly in a sagittal or parasagittal scanning plane in the epigastrium. Important vascular landmarks including the inferior vena cava (IVC) and the superior mesenteric vein was marked the standard scanning plane of the antrum [[
Graph: Fig. 1 Example of a gastric ultrasonographic image. The antrum was located superficially between the left lobe of the liver anteriorly and the pancreas posteriorly in a sagittal or parasagittal scanning plane in the epigastrium. Important vascular landmarks including the inferior vena cava (IVC) and the superior mesenteric vein was marked the standard scanning plane of the antrum. Antralcross-sectional area (CSA) can be measured by using two perpendicular diameters (antero-posterior diameter and craniocaudal diameter) and the formula of the area of an ellipse
Surgical data of the patients included: patient characteristics (age, weight, height, calculate BMI, American Society of Anesthesiologists class), airway assessment (Mallampati class, thyromental distance) and operative details (time). Haemodynamic variables including systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) were recorded in the moment of before the induction (baseline T
Patients were interviewed 24 h after leaving the recovery room and were asked about the presence of a sore throat, dry throat, hoarseness, nausea and/or vomiting. Nausea symptoms were graded using a visual analogue scale (VAS) by the patient as nill, mild, moderate or severe [[
Sample size was performed using SPSS software based on our preliminary study showing an increased mean antral CSA for patients in LMA Supreme group and I-gel group (405 ± 105 and 400 ± 95, respectively) compared with patients in endotracheal tube group (340 ± 94) at the end of the surgery. To detect differences in antral CSA at the end of the surgery with an SD of 95, the sample size was calculated as 29 per group at a power of 80% and a two-tailed α-error of 5%. We enrolled 100 patients in total to countervail potential dropouts.
Statistical analysis was conducted using the SPSS 17.0 software (SPSS Inc., Chicago, USA). Studied data were expressed as mean ± SD, or in frequencies and percentages when appropriate. We compared normally distributed continuous variables among the groups using one-way ANOVA, and used a least significant difference (LSD) procedure for post hoc comparisons. Mann-Whitney U tests were applied for intergroup comparisons when a significant difference was detected between the groups. Categorical variables were compared using chi-squared test. All comparisons were two sides and a P value of less than 0.05 was required to exclude the null hypothesis.
A total of 100 patients were enrolled for this study. There was one exclusion for cancellation (Fig. 2). There were allocated as follows: 33 patients included in the I-gel group, 33 in the LMA Supreme group and 33 in the tracheal intubation group. There were no significant differences in patient characteristics among the groups (Table 1). The antral CSAs were not significantly different among three groups in the moment of before induction (P = 0.451), the moment of after induction (P = 0.456) and the moment of after the surgery (P = 0.195). There was no difference in the antral cross-sectional area among Group S, Group I and Group T (P = 0.814; Table 2).
Graph: Fig. 2 Consort flow chart that outline patients assignment and treatment protocols. Patients were allocated into three groups (Group S, Group I, Group T) to receive airway management with LMA Supreme, I-gel or tracheal tube respectively, following a computer-generated randomization code
Baseline Characteristics
Variable Group I Group S Group T P value Age (year) 39.57 (12.03) 42.43 (11.75) 43.40 (12.07) 0.174 Weight (kg) 59.07 (6.29) 59.37(7.10) 63.13(7.93) 0.054 Height (cm) 159.20 (5.60) 159.83 (5.15) 160.93 (4.43) 0.413 BMI (kg m−2) 23.38 (2.95) 23.29 (3.05) 24.36 (2.68) 0.289 ASA physical status 0.475 I 23 (76.6%) 25 (83.3%) 21 (70%) II 7 (23.4%) 5 (16.7%) 9 (30%) Mallampati score 0.600 I 1 (3.3%) 3 (10%) 1 (3.3%) II 18 (60%) 15 (50%) 20 (66.7%) III 11 (36.7%) 12 (40%) 9 (30%) Thyromental distance (cm) 7.67 (0.83) 7.78 (0.70) 7.48 (0.55) 0.940 Duration of anesthesia (min) 127.13 (38.78) 129.47 (37.71) 130.40 (34.90) 0.921 Duration of pneumoperitoneum (min) 92.20 (39.99) 95.83 (37.95) 95.20 (32.81) 0.257
Data are expressed as number (percentage) or mean (SD). ASA, American Society of Anesthesiologists. Group I, Group I-gel; Group S, Group LMA Supreme; Group T, Group tracheal tube
Antral cross-sectional area
Group I Group S Group T P value S1 330.41 ± 105.21 348.74 ± 151.05 370.09 ± 101.39 0.451 S2 362.20 ± 106.14 391.86 ± 152.00 401.59 ± 115.95 0.456 S3 401.13 ± 108.52 410.32 ± 153.57 355.74 ± 103.70 0.195
Data are expressed as mean ± SD. S1, antral CSA was noted before induction; S2, antral CSA was noted after induction; S3, antral CSA was noted after surgery. Group I, Group I-gel; Group S, Group LMA Supreme; Group T, Group tracheal tube This data are analyzed by Repeated Measures F = 0.206, P = 0.814
The SBP, DBP and HR are summarized for each time point in Table 3. There were no significant differences in SBP, DBP and HR among the three groups in the moment of T1, T2 and T4. The SBP, DBP and HR were significantly higher in the tracheal tube group than in the LMA-S and I-gel groups after insertion(T3) (P < 0.0001). SBP and HR were significantly higher in the tracheal tube group than in the LMA-S and I-gel groups after their removal(T5) (P < 0.01). Compared with T2 and T4, the SBP, DBP and HR of the tracheal tube group were significantly increased in T3 and T5.
Haemodynamic data
Group T1 T2 T3 T4 T5 SBP Group I 124.17 ± 18.35 108.47 ± 11.12 109.23 ± 14.07c 115.13 ± 15.96 117.43 ± 14.40 c mmHg Group S 125.40 ± 12.09 114.10 ± 11.58 111.10 ± 13.28 c 116.03 ± 13.10 114.43 ± 11.20 c Group T 124.97 ± 15.97 106.77 ± 13.40 125.60 ± 16.02a, c 113.17 ± 10.95 124.37 ± 11.52b, c DBP Group I 72.10 ± 10.76 64.60 ± 8.17 62.30 ± 10.33 c 68.03 ± 10.31 67.93 ± 9.15 mmHg Group S 72.53 ± 7.66 64.90 ± 7.24 64.40 ± 9.13 c 67.30 ± 9.61 64.80 ± 7.30 Group T 69.13 ± 9.42 60.97 ± 8.64 73.83 ± 11.15a, c 64.27 ± 7.87 71.07 ± 7.57b HR Group I 77.40 ± 7.87 64.53 ± 6.45 65.70 ± 8.19 c 72.20 ± 10.23 70.63 ± 9.02b, c bpm Group S 78.07 ± 14.73 66.87 ± 8.35 66.80 ± 10.90 c 73.73 ± 10.72 74.00 ± 9.91 c Group T 79.27 ± 13.70 65.40 ± 11.20 85.57 ± 13.57a, c 71.17 ± 7.27 85.73 ± 6.96b, c
Data are expressed as mean ± SD. Compare with T
Data regarding sore throat, hoarseness, dry throat, nausea and vomiting are summarized in Table 4. There was no difference in dry throat, nausea and vomiting but sore throat and hoarseness were statistically different between groups (P < 0.0001). None of the three groups of patients had a serious postoperative complications of reflux aspiration.
Postoperative morbidity data(%)
Complication event Group I Group S Group T P value sore throat 0 (0.0) 2 (6.7) 15 (50) 0.000 hoarseness 1 (3.3) 2 (6.7) 11 (36.7) 0.000 dry throat 25 (83.3) 25 (83.3) 24 (80) 0.927 Nausea 0.135 No nausea 21 (70) 25 (83.3) 18 (60) Mild nausea 4 (13.3) 3 (10) 7 (23.4) Moderate nausea 5 (16.7) 2 (6.7) 3 (10) Severe nausea 0 (0) 0 (0.0) 2 (6.6) vomiting 7 (23.4) 2 (6.7) 5 (16.7) 0.200
Data are number/patients with data (percentage). Group I, Group I-gel; Group S, Group LMA Supreme; Group T, Group tracheal tube
I-gel is a relatively new kind of SADs, which is made of medical grade thermoplastic elastomer and designed according to anatomical characteristics. The soft noninflatable cuff is well sealed around perilaryngeal framework, and effectively isolates laryngeal opening from oropharyngeal opening. The lack of inflatable cuff might result in lower incidence of sore throat [[
In this prospective randomized trial, we found that the antral cross-sectional areas in different points of time were similar between the LMA-S, I-gel and endotracheal tube. However, the blood pressure and heart rate of patients in the tracheal tube group increased significantly after intubation and after extubation. Postoperative sore throat and hoarseness were higher in endotracheal tube group. Other postoperative signs of poor tolerance of the devices (dry throat, nausea and vomiting) were similar between groups.
Our study provides additional information to evaluate the gastric insufflations in choosing the ventilation devices in laparoscopic gynecological surgery. The tracheal tube is the "gold standard" for avoiding gastric aspiration and reflux in general anesthesia. However, the use of supraglottic airway devices has a series of advantages, such as lower fluctuations in hemodynamics, easier insertion than tracheal tube and a significant reduction in the incidence of sore throat and hoarseness and so on. In recent years, SADs have been widely used in various clinical operations [[
Our study has several limitations. First of all, this is only the single center. Thus, a multicenter study would be better to further determine this hypothesis. Sencondly, the patient population was not overweight and of reasonable general health. Thirdly, the devices are from different operators and I-gel gastric channel is much smaller than Supreme. Lastly, we did not assess for amount of air that was passes onto the small bowel that may have caused postoperative abdominal discomfort.
This study shows that both LMA-Supreme and I-gel were effective for controlled ventilation after the creation of pneumoperitoneum in the Trendelenburg position. They have potential advantages of stable hemodynamic parameters and lower incidence of sore throat and hoarseness compared to tracheal tube, also do not cause obvious gastric insufflations. Thus LMA-Supreme and I-gel can be widely used as alternative to endotracheal intubation for the short laparoscopic gynecological surgery.
This study is supported by Key Project of Excellent Youth in Higher Education Institution of Anhui Province (gxyqZD2018028).
We thank our departmental colleagues for their help in recruiting patients for this study. All authors declare no competing interests.
QY and YL designed this study and wrote the manuscript. QY and DW performed the experiments. WF assisted with data analysis. GW revised the final manuscript. All the authors contributed to the final version of the manuscript. The authors read and approved the final manuscript.
The datasets analysed during the current study are available from the corresponding author upon reasonable request.
This study was approved by the ethics committee of the First Affiliated Hospital of Anhui Medical University on October 6, 2016(approval number: PJ2016-08-06) and written informed consents have been obtained from all patients.
Not applicable.
The authors declare that they have no competing interests.
• SAD
- supraglottic airway device
• CSA
- cross-sectional area
• PAWs
- peak airway pressures
- EtCO
2 - end-tidal CO
2
• IAP
- intra-abdominal pressure
• IVC
- inferior vena cava
• SPO2
- blood oxygen saturation leve
• VAS
- visual acuity scores
• ASA
- American Society of Anesthesiologists
• SBP
- Systolic blood pressure
• DBP
- diastolic blood pressure
• HR
- heart rate
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By Qiuping Ye; Di Wu; Weiping Fang; Gordon Tin Chun Wong and Yao Lu
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