Abstract
Background
Jet ventilation technique can be used to supply oxygen to prevent hypoxia for patients undergoing flexible bronchoscopy. An optimal access route for jet ventilation technique during flexible bronchoscopy has not been determined. Our aim was to compare the effectiveness and safety of subglottic jet ventilation via a new introducer (Safe Easy Endotracheal Kit-flexible, SEEKflex) versus supraglottic jet ventilation via Wei nasal jet tube in patients undergoing flexible bronchoscopy under moderate-to-deep sedation.
Methods
This was a single-center randomized controlled trial. 352 patients scheduled to undergo flexible bronchoscopy under moderate-to-deep sedation were randomly assigned to the following two groups: the subglottic jet ventilation group, and the supraglottic jet ventilation group. The primary outcome was hypoxia during flexible bronchoscopy.
Results
Subglottic jet ventilation decreased the incidence of hypoxia from 16.6% to 6.0% compared with supraglottic jet ventilation [relative risk (RR) for hypoxia, 0.364, 95% CI 0.18 to 0.72; P 0.002]. The incidence of severe hypoxia was also significantly diminished in the subglottic jet ventilation group compared with the supraglottic jet ventilation group (3% vs. 8.6%; RR 0.351, 95% CI 0.12 to 0.95; P 0.030). The subglottic jet ventilation group needed significantly less jaw thrust (4.8% vs. 12.9%; RR 0.374, 95% CI 0.17 to 0.82; P 0.010), and mask ventilation (2.4% vs. 7.4%; RR 0.327, 95% CI 0.10 to 0.99; P 0.037). No gastric insufflation occurred in the subglottic jet ventilation group, 31 instances occurred in the supraglottic jet ventilation group (P < 0.001). There was no significant difference between the two groups in terms of other adverse events including xerostomia, pharyngalgia, nasal bleeding.
Conclusions
Subglottic jet ventilation more effectively reduces the incidence of hypoxia in patients undergoing flexible bronchoscopy under moderate-to-deep sedation when compared with supraglottic jet ventilation. Subglottic jet ventilation via the SEEKflex may be a preferable approach.
Trial registration
ChiCTR2300076139.
Supplementary Information
The online version contains supplementary material available at 10.1186/s12871-025-03535-8.
Keywords: Airway management, Flexible bronchoscopy, Hypoxia, Jet ventilation, SEEKflex
Introduction
Flexible bronchoscopy (FB) has undoubtedly become an indispensable tool in the evaluation, diagnosis, and treatment of various respiratory diseases [1, 2]. It is estimated that over 500,000 bronchoscopies are performed annually in the United States [3]. American College of Chest Physicians recommendations state that some degree of sedation should be applied to all patients receiving bronchoscopy unless contraindicated to improve patient satisfaction and procedure tolerability [4]. Usually, FB is accomplished under topical anesthesia supplemented by intravenous sedation or anesthesia [5, 6]. However, bronchoscopic sedation and anesthesia have been significantly associated with hypoxia.
Hypoxia is a common occurrence during FB, with a reported incidence up to 75% [7], which is mainly due to coexisting pulmonary illness or anesthesia/sedation- induced respiratory depression or bronchoscopy itself occupying the partial tracheal area and causing airflow limitation or all of the above [5, 8, 9]. Therefore, several oxygenation/ventilation techniques have been used to supply oxygen to prevent hypoxia during FB particularly in the elderly and patients with comorbidities. One viable technique to prevent hypoxia during FB is supraglottic jet ventilation via Wei nasal jet tube (WNJ) [10–12]. Wei et al. showed that supraglottic jet ventilation via WNJ reduced the incidence of hypoxia from 86% to 9.1% during FB under deep sedation when compared to nasal cannula oxygenation [11]. Zha et al. and colleagues suggested that supraglottic jet ventilation via WNJ decreased hypoxia by 23.9% during FB under moderate to deep sedation compared to nasal cannula oxygenation [12]. Subglottic jet ventilation via a small catheter is another frequently used jet ventilation technique during FB. Hautmann et al. reported that subglottic jet ventilation via a 14 F catheter was used in interventional fiberoptic bronchoscopic procedures and 3% of patients experienced hypoxia with transcutaneous partial pressure of oxygen < 60mmHg [13]. In our previous report, subglottic jet ventilation via a new device (Safe Easy Endotracheal Kit-flexible, SEEKflex) was performed in a patient receiving bronchoscopic balloon dilation under general anesthesia, and was demonstrated feasible without significant complications, more detailed descriptions of subglottic jet ventilation via SEEKflex have been published previously [14]. However, it remains unclear which type of these jet ventilation techniques is superior for preventing hypoxia during FB.
Therefore, a prospective, randomized controlled trial was undertaken to compare the effectiveness and safety of subglottic jet ventilation versus supraglottic jet ventilation in patients undergoing FB to provide evidence for clinical practice. The hypothesis was that subglottic jet ventilation would result in a lower incidence of hypoxia compared with supraglottic jet ventilation.
Materials and methods
Study design
A single-center, patient-blind, prospective randomized controlled trial was conducted in The First Hospital of Putian (Fujian, China) and was approved by the Ethics Committee of The First Hospital of Putian (2022-049). The trial was registered before patient enrollment in the Chinese Clinical Trial Registry on September 26, 2023 (ChiCTR2300076139, principal investigator Yaohua YU). The clinical trial was conducted in accordance with the Declaration of Helsinki. Written informed consents were obtained from all patients. Prior to the trial initiation, all participating anesthesiologists need to attend the training on intubation techniques of SEEKflex and WNJ, and airway management techniques with subglottic jet ventilation and supraglottic jet ventilation including application, settings, adjustment and so on. The attending anesthetists with more than 5 years’ experience in anesthesia and nasotracheal intubation used both techniques during FB for at least 2 months before trial enrollment began.
Participants
Patients undergoing FB under moderate-to-deep sedation were recruited. Inclusion criteria were as follows: (1) 18 year ≤ age ≤ 65 year; (2) American Society of Anesthesiologists (ASA) Physical Status I-III; (3) body mass index (BMI) 19–29 kg.m-2; (4) sign informed consent voluntarily. Exclusion criteria were as follows: (1) pulmonary bulla or pneumothorax; (2) history of pulmonary lobectomy, degree of tracheostenosis > 50%; (3) oxygen saturation measured by pulse oximetry (SpO2) in room air < 90%; (4) preexisting asthma; (5) massive hemoptysis or coagulopathy disorders; (6) acute myocardial infarction within the last six months, uncontrolled hypertension, severe arrhythmia; (7) severe liver and renal dysfunction; (8) history of nasopharyngeal surgery, nasal malformation; (9) pregnancy.
Randomization and blinding
Eligible patients were randomly allocated in a 1:1 ratio to either the subglottic group receiving subglottic jet ventilation via SEEKflex or the supraglottic group receiving supraglottic jet ventilation via WNJ. The randomization sequence was generated with the use of SPSS 24.0 software by a person who knew little about the trial and did not participate in the allocations of patients. Random sequences were secured in sealed, opaque envelopes. After determining that the subject met the enrollment criteria, the envelope was opened and the anesthesiologist was informed of the grouping information. Anesthesiologists and bronchoscopists were not blinded to the trial intervention because of the notably different appearance of airway devices.
Interventions
All procedures were performed in the bronchoscopy suite. Patients were premedicated with nebulisation of 2% lidocaine for 15 min in the preparation room. The baseline data of patients were collected and standard monitoring including electrocardiogram, noninvasive blood pressure measured every 5 min, SpO2 were applied to all patients. Before sedation, all study subjects were administered 2 mL of 1% lidocaine to both nostrils and then preoxygenated for 3 min with 6 L.minute− 1 of 100% oxygen using a face mask. Sedation was conducted by target-controlled infusion of propofol and remifentanil with an initial effect-site concentration of 2 µg.mL− 1 and 3.0 µg.L− 1, respectively. Sedation level was evaluated using the Modified Observer Assessment of Alertness/Sedation Scale (MOAA/S). Target-controlled infusion of propofol and remifentanil could be adjusted based on the clinical signs and MOAA/S (1 ≤ MOAA/S score ≤ 3) to achieve and maintain a moderate to deep sedation throughout the procedure. When the target sedation level was achieved, the bronchoscope was inserted into one nostril and then glottic view was obtained and was sprayed with 1% lidocaine via the working channel of the bronchoscope. Subsequently, the lubricated WNJ in the supraglottic group and the reshaped and lubricated SEEKflex in the subglottic group were gently inserted into another nostril.
In the supraglottic group, the WNJ was advanced and its tip was positioned 1 cm above the glottis under the direct vision of the bronchoscope. If the insertion of WNJ in one nostril failed thrice consecutively, the other nostril would be tried and the access route of the bronchoscope could be via the contralateral nostril or the mouth. If it failed again, the patient would be excluded. The position of WNJ was checked again under the direct vision of the bronchoscope at the end of the procedure.
In the subglottic group, the SEEKflex was advanced into the glottic opening under the direct vision of the bronchoscope (Fig. 1, Supplementary video 1 in Supporting Information). If needed, the SEEKflex handle was manoeuvred slightly toward the left or right or posterior to align SEEKflex with the glottis. If these procedures could not facilitate the SEEKflex advancement into the glottis, the anteriorly curved part of SEEKflex could be adjusted including anterior bending length and bending angle. If it failed thrice, the patient would be excluded. After the SEEKflex was placed through the glottic opening, its inner guide core was removed, and its tip was positioned 4 cm above the carina under the direct vision of the bronchoscope.
Fig. 1.
Nasotracheal placement of SEEKflex (red arrows). a SEEKflex inserted in a sharp angle into the nasal cavity. b SEEKflex tip up to pass over the glottic opening under the direct vision of the flexible bronchoscope
After the bronchoscope passed the glottis, 1% lidocaine was sprayed directly into the trachea, carina, two mainstem bronchi via the working channel of the bronchoscope. Then the WNJ via its jet catheter and the SEEKflex via the matching adapter were connected to an automated jet ventilator (TKR-300CG, Jiangxi TELI Anaethesia & Respiration Equipment Co.Itd, China) and both were secured at the level of the nostri. The following respiratory parameters were set equally in all patients: FiO2 100%, driving pressure 150 kPa, respiratory rate 18 bpm, inspiratory to expiratory ratio (I: E) 1:2. A matching breathing gas humidifier was applied for all patients. During ventilation symmetrical chest rises and falls were observed, but sometimes chest excursion in the supraglottic group could not be achieved even after adjustments.
Jet ventilation was stopped when the procedure was completed and the spontaneous breathing recovered. If the patient in the subglottic group was in the apnea after the procedure, an oral airway should be placed in the mouth to allow egress of inspired air to prevent barotrauma. Finally, SEEKflex and WNJ were removed when the patients were conscious, and they were transferred into the postanesthesia care unit to be monitored for at least 30 min.
When hypoxia occurred during the procedure, remedial interventions were conducted using the following sequence: (1) reducing or withholding medication; (2) adjusting respiratory rate to 30 bpm, increasing the driving pressure to 200 kPa; (3) jaw thrust; (4) pausing the procedure and mask ventilation; (5) tracheal intubation for mechanical ventilation.
Data collection
The primary outcome was hypoxia during the procedure, which was defined as SpO2 < 90% for >5 s [11]. Secondary outcomes included (1) subclinical respiratory depression (90% ≤ SpO2 < 95%), severe hypoxia (SpO2 < 75% at any time or SpO2 < 90% for >60 s) [11], and remedial interventions for hypoxia; (2) other sedation-related adverse events using the World Society of Intravenous Anesthesia (SIVA) adverse sedation event reporting tool [15]; (3) adverse events related to jet ventilation including xerostomia, pharyngalgia, nasal bleeding, gastric insufflation, barotrauma, carbon dioxide accumulation. Nasal bleeding was assessed by the bronchoscope. Lung ultrasonography was used to monitor for pneumothorax before induction and when patients left postanesthesia care unit. If suspected, chest computed tomography would be performed. Gastric ultrasound examination was used to assess gastric insufflation before and after jet ventilation by the measurement of the antral cross-sectional area and/or presence of air artefacts in the antrum. Arterial blood samples were drawn for blood gas analyses before the sedation and after the procedure to determine PaO2, PaCO2, and arterial pH.
A satisfaction evaluation scale which ranged from 0 to 10 with a higher score indicating better satisfaction was evaluated by bronchoscopists at the end of the procedure and by the patients before discharge [16].
Sample size and statistical analysis
According to previous study and our clinical experience, approximately 15% of patients experienced hypoxia in the supraglottic group [12] vs. approximately 5% in the subglottic group [13]. Subglottic jet ventilation was assumed decrease the incidence of hypoxia from 15% to 5%. Given an α = 0.05 and a power of 80%, it was estimated that 282 patients would be required for the study. Assuming a dropout rate of 20%, a total of 352 patients would be required. The sample size was calculated by PASS software (version 15.0).
The primary outcome (the incidence of hypoxia) was analyzed using Pearson’s chi-square test, the difference between the two groups was expressed as the relative risk(RR) and 95% CI. The secondary outcomes which were categorical variables and described as numbers and percentages were analyzed using Pearson’s chi-square test or Fisher’s precision, and the differences were expressed as RR and 95% CI. Patient characteristics were evaluated between the two groups using Pearson’s chi-square test for sex, ASA, Wilcoxon rank-sum test for age, BMI, baseline SpO2, PaCO2 before sedation, and two-sample t-test for PaO2 before sedation. Procedure characteristics including procedure time, resuscitation time, anesthetic dosage, PaO2 after procedure which were continuous variables with a non-Gaussian distribution were compared using the Wilcoxon rank test. PaCO2 after procedure with Gaussian distribution was analyzed using two-sample t-test. The satisfaction of bronchoscopists and patients were also compared using Wilcoxon rank-sum test. All statistical analyses were performed using IBM SPSS Statistics version 24.0.
Results
Between October 20, 2023 and November 25, 2024, a total of 735 patients scheduled for FB were assessed, of which 383 were excluded and 352 were randomly assigned to either the subglottic group or the supraglottic group. 23 patients were excluded after randomization. Reasons for exclusion included changing the plan from FB to bronchoscope intervention therapy, failure of WNJ/SEEKflex insertion and changing to another ventilation mode, laryngospasm during procedure, incomplete information due to inability to visualize the antrum before sedation. Finally, 329 patients were included for data analysis. The numbers of patients at each study phase are presented in the trial flow chart (Fig. 2).
Fig. 2.
CONSORT trial flow chart
The baseline characteristics of patients and procedure characteristics are presented in Tables 1 and 2, respectively. As this study was a randomized clinical trial, the baseline characteristics of patients between two groups, including age, sex, BMI, ASA classification, baseline SpO2, PaO2 before sedation, PaCO2 before sedation were comparable. The two groups also did not differ in terms of procedure characteristics including procedure time, resuscitation time, anesthetic dosage, PaCO2 after procedure. This finding showed that subglottic jet ventilation did not affect the procedure time or the anesthetic dosage. The two groups were comparable in terms of the satisfaction of bronchoscopists and patients, which indicated the subglottic jet ventilation was acceptable and there was no preference between the two types of jet ventilation techniques in clinical practice.
Table 1.
The baseline characteristics of patients. Values are mean (SD), median (IQR) or number (proportion)
| Characteristic | Supraglottic group (n = 163) | Subglottic group (n = 166) |
|---|---|---|
| Age; yr | 58 (50–61) | 56 (50–61) |
| Sex (male, female) | (111, 52) | (103, 63) |
| BMI; kg/m2 | 21.8 (20.3–24.3) | 22.03 (20.7–23.4) |
| ASA(I, II, III) | (23, 112, 28) | (21, 118, 27) |
| Baseline SpO2; % | 96 (94–98) | 97 (95–99) |
| PaO2 before sedation; mmHg | 83.0 (13.3) | 82.5 (12.0) |
| PaCO2 before sedation; mmHg | 39 (37–43) | 40 (37–43) |
SD Standard deviation, IQR Interquartile range. BMI Body mass index, ASA American Society of Anesthesiologists
Table 2.
Procedure data, anesthetic dosage, arterial blood gas analysis and satisfaction. Values are mean (SD), median (IQR)
| Supraglottic group (n = 163) | Subglottic group (n = 166) | P value | |
|---|---|---|---|
| Procedure time; min | 8 (6–10) | 7 (6–11) | 0.192 |
| Resuscitation time; min | 2 (1–4) | 3 (1–5) | 0.278 |
| Propofol dose; mg | 141 (118–172) | 138 (110–170) | 0.300 |
| Remifentanil dose; ug | 116 (93–140) | 109 (97–140) | 0.728 |
| PaO2 after procedure; mmHg | 143 (100–204) | 196 (130–270) | < 0.001 |
| PaCO2 after procedure; mmHg | 55.8 (10.8) | 53.9 (9.7) | 0.064 |
| Patient satisfaction score | 9 (9–10) | 9 (9–10) | 0.133 |
| Bronchoscopist satisfaction score | 9 (8–9) | 9 (8–9) | 0.558 |
SD Standard deviation, IQR Interquartile range
Adverse events and interventions related to hypoxia are listed in Table 3, the use of subglottic jet ventilation significantly decreased the incidence of hypoxia in patients with moderate-to-deep sedation during FB from 16.6% to 6.0% (RR 0.364, 95% CI 0.18 to 0.72; P 0.002) compared with supraglottic jet ventilation. The incidence of severe hypoxia in the subglottic group was also significantly lower compared with the supraglottic group (3% vs. 8.6%; RR 0.351, 95% CI 0.12 to 0.95; P 0.03). However, there was no statistically significant difference in terms of subclinical respiratory depression between the two groups. When accounting for the interventions for hypoxia, the subglottic group showed significantly less need for interventions included reducing/withholding the anesthesia medication (7.8% in the subglottic group vs. 19% in the supraglottic group; RR 0.412, 95% CI 0.22 to 0.75; P 0.003), adjusting jet ventilation parameters (6.0% vs. 16.6%; RR 0.364, 95% CI 0.18 to 0.72; P 0.002), jaw thrust (4.8% vs. 12.9%; RR 0.374, 95% CI 0.17 to 0.82; P 0.010), and mask ventilation (2.4% vs. 7.4%; RR 0.327, 95% CI 0.10 to 0.99; P 0.037).
Table 3.
Adverse events and interventions related to hypoxia. Values are number (proportion)
| Supraglottic group (n = 163) | Subglottic group (n = 166) | Relative Risk (95% CI) | P value | |
|---|---|---|---|---|
| Primary outcome: hypoxia | 27 (16.6) | 10 (6.0) | 0.364(0.18, 0.72) | 0.002 |
| Subclinical respiratory depression | 20 (12.3) | 17 (10.2) | 0.835(0.45, 1.53) | 0.560 |
| Severe hypoxia | 14 (8.6) | 5 (3.0) | 0.351(0.12, 0.95) | 0.030 |
| Interventions | ||||
| Reducing or withholding medication | 31 (19) | 13 (7.8) | 0.412(0.22, 0.75) | 0.003 |
| Increasing driving pressure/adjusting respiratory rate | 27 (16.6) | 10 (6) | 0.364(0.18, 0.72) | 0.002 |
| Jaw lift | 21 (12.9) | 8 (4.8) | 0.374(0.17, 0.82) | 0.010 |
| Mask ventilation | 12 (7.4) | 4 (2.4) | 0.327(0.10, 0.99) | 0.037 |
According to the adverse event reporting tool proposed by the world SIVA International Sedation Task Force, other sedation adverse events were recorded in Table 4. Minimal adverse events including nausea/vomiting, hypersalivation, recovery agitation and minor adverse events including bradycardia, tachycardia, hypotension, hypertension were similar in the two groups, these adverse events were managed successfully. No sentinel adverse events occurred in either group.
Table 4.
Other adverse events related to sedation. Values are number (proportion)
| Supraglottic group (n = 163) | Subglottic group (n = 166) | Relative Risk (95% CI) | P value | |
|---|---|---|---|---|
| Minimal risk adverse events | ||||
| Nausea/retching | 9 (5.5) | 11 (6.6) | 1.20 (0.51, 2.81) | 0.675 |
| Muscle rigidity, myoclonus | 0 | 0 | - | - |
| Hypersalivation | 14 (8.6) | 16 (9.6) | 1.122(0.56, 2.22) | 0.741 |
| Paradoxical response | 0 | 0 | - | - |
| Recovery agitation | 1 (0.6) | 0 | - | 0.993 |
| Recovery delay | 0 | 0 | - | - |
| Minor risk adverse events | ||||
| Airway obstructed | 0 | 0 | - | - |
| Allergic reaction without anaphylaxis | 0 | 0 | - | - |
| Bradycardia | 13 (8.0) | 14 (8.4) | 1.057 (0.51, 2.18) | 0.880 |
| Tachycardia | 20 (12.3) | 15 (9.0) | 0.736 (0.39, 1.38) | 0.342 |
| Hypertension | 2 (1.2) | 5 (3.0) | 2.455 (0.48, 12.47) | 0.459 |
| Hypotension | 36 (22.1) | 29 (17.5) | 0.791 (0.51, 1.22) | 0.293 |
| Seizure | 0 | 0 | - | - |
| Sentinel risk adverse events | ||||
| Cardiovascular collapse/shock | 0 | 0 | - | - |
| Cardiac arrest/absent pulse | 0 | 0 | - | - |
Adverse events and interventions related to jet ventilation were listed in Table 5. 16.3% of patients in the subglottic group and 22.7% of patients in the supraglottic group experienced xerostomia which was tolerable, there was no statistically significant difference (RR 0.717, 95% CI 0.45 to 1.12; P 0.140). Additionally, pharyngalgia (6.6% vs. 7.4%; RR 0.900, 95% CI 0.40 to 1.98; P 0.794) and nasal bleeding (8.4% vs. 14.7%; RR 0.573, 95% CI 0.30 to 1.06; P 0.074) did not differ between the two groups, which were clinically minor without any interventions for treatment. In the subglottic group, no gastric insufflation was detected by ultrasonography. In contrast, 19% of patients in the supraglottic group were detected the entry of air into the stomach, the difference between the two groups was statistically significant (P < 0.001). The lower incidence of postoperative moderate hypercapnia (PaCO2 > 60mmHg) was noted in the subglottic group (21.1%) compared with the supraglottic group (33.7%) (RR 0.625, 95% CI 0.43 to 0.90; P 0.01); no severe hypercapnia (PaCO2 > 80mmHg) was noted in either group. No barotrauma was found in any patients.
Table 5.
Adverse events related to jet ventilation. Values are number (proportion)
| Supraglottic group (n = 163) | Subglottic group (n = 166) | Relative Risk (95% CI) | P value | |
|---|---|---|---|---|
| Hoarseness | 0 | 0 | - | - |
| Pharyngalgia | 12 (7.4) | 11 (6.6) | 0.900 (0.40, 1.98) | 0.794 |
| Xerostomia | 37 (22.7) | 27 (16.3) | 0.717 (0.45, 1.12) | 0.140 |
| Nasal bleeding | 24 (14.7) | 14 (8.4) | 0.573 (0.30, 1.06) | 0.074 |
| Tracheal mucosa injury/Hemorrhage | 0 | 0 | - | - |
| Barotrauma | 0 | 0 | - | - |
| Gastric insufflation | 31 (19) | 0 | - | < 0.001 |
| Moderate hypercapnia (PaCO2 > 60mmHg) | 55 (33.7) | 35 (21.1) | 0.625 (0.43,0.90) | 0.01 |
Discussion
Our study showed that using subglottic jet ventilation significantly reduced the incidence of hypoxia during FB under moderate to deep sedation when compared with supraglottic jet ventilation. Moreover, our study further re-affirmed earlier work that subglottic jet ventilation via SEEKflex was a feasible approach to provide adequate oxygenation and ventilation during therapeutic FB under general anesthesia [14].
Jet ventilation was first described in the late 1960s. Jet ventilation could be performed in many different ways, including subglottic or supraglottic jet ventilation [17, 18]. Supraglottic jet ventilation has been proved to be an effective approach to reduce the incidence of hypoxia in sedated patients during FB [11, 12]. Consistent with the previous study, our study showed that the incidence of hypoxia was 16.6% when supraglottic jet ventilation was used. However, the incidence of hypoxia decreased to 6.0% when subglottic jet ventilation was used. Our results demonstrated the higher effectiveness of subglottic jet ventilation to maintain oxygenation during FB. The difference in the incidence of hypoxia may partly be caused by the effect of jet cannula location on tracheal airflow. Although the distal end of WNJ was attempted to introduce toward the glottis under the view of the bronchoscope to achieve the best alignment, not all jet gases and jet stream entraining surrounding air during supraglottic jet ventilation could enter though the glottis downwards airway. This could be explained by the occupation of the bronchoscope and partial jet gas being reflected away or possibly downward toward the oesophagus and stomach. Approximately 19% of patients in the supraglottic group experienced gastric distension. Subglottic jet ventilation using the same settings which provided jet pulse below the vocal cord, may produce a larger tracheal airflow. No gastric distension occurred in patients with subglottic jet ventilation. Moderate hypercapnia was observed in 33.7% of all measurements during supraglottic jet ventilation, in 21.1% during subglottic jet ventilation. It was possible that the tidal volumes which could be administered were greater with subglottic jet ventilation than supraglottic jet ventilation.
Improved outcomes with subglottic jet ventilation were generally consistent with the report of Hautmann et al. [13], who reported that 3% of patients receiving the subglottic jet ventilation during interventional fiberoptic bronchoscopic procedures experienced hypoxia. The usefulness of subglottic jet ventilation for FB in previous study was reported mostly as case report or case series with small numbers of patients [19, 20]. Subglottic jet ventilation was also widely used for elective complex thoracic surgery and laryngeal surgery [17, 21]. Herein, our results demonstrated the effectiveness and safety of subglottic jet ventilation in maintaining oxygenation and ventilation during FB under moderate to deep sedation.
The adverse events related to jet ventilation and sedation were minor and easily manageable. Xerostomia and pharyngalgia are common complications caused by jet ventilation [22, 23]. Procedure time was found to have the greatest correlation with postoperative pharyngalgia/xerostomia [24]. Warmed and humidifed oxygen may reduce the risk [25]. As the duration of the procedure was short and humidifed oxygen was used, the incidence of pharyngalgia and xerostomia in the two groups were low. There was no significant difference between the two groups in terms of pharyngalgia and xerostomia. No barotrauma occurred in any patients. To reduce the risk of barotrauma, we maintained a relative low jet ventilation pressure of 150 kPa, limited I: E, and patients with obesity and/or obvious airway stenosis were exclusive. More importantly, it was essential to carefully observe chest wall movement to ensure the unobstructed outflow of intrathoracic air after each inspiration. No gastric insufflation was detected by ultrasonography of the antrum in patients with subglottic jet ventilation, which was far lower than that in patients with supraglottic jet ventilation. As subglottic jet ventilation could not increase gastric insufflation which increased the risk of gastric reflux and aspiration, it could potentially improve safety.
Multiple catheters which have been reported to perform subglottic jet ventilation include bronchial blockers [21], soft-suction catheter [20], Cook airway exchange catheter [26], Laserjet [27] and Hunsaker [17, 28]. SEEKflex have been used extensively at our institution for bronchoscopic procedures. Given that most of flexible bronchoscopies are short and performed on an outpatient basis, it is necessary to make manipulation simple and convenient in terms of airway management as well as satisfy utmost airway control. The SEEKflex is intended for one-time use, there is no need for cleaning or disinfection [29]. Nasotracheal placement of SEEKflex under direct visualization of flexible bronchoscope don’t required accessory tools such as laryngendoscope or even muscle relaxation, which could reduce cost-effectiveness and time-effectiveness to some extent. Moreover, one of the most important features is that the SEEKflex could function as a guide for intubation [30]. This is of particular benefit in patients with potentially difficult airway including ankylosing spondylitis, neck rigidity, and in the setting where bleeding impairs the glottis visualization and results in the difficulty of intubation. Emergent rapid sequence intubation is a great challenge for the patient with a potentially difficult airway when the patient experiences severe hypoxia or hemorrhoea and requires intubation during procedure. SEEKflex could be used to maintain tracheal access to mitigate the risk of tracheal intubation failure. From this point of view, it may be superior to other oxygenation/ventilation technologies.
This study had some limitations. Anesthesiologists and bronchoscopists were not blinded due to the different appearance of airway devices, which might affect the power of this study. However, the major parameter hypoxia was objective in our study. In addition, neither the WNJ tube nor the SEEKflex is equipped with a pressure monitoring tube, therefore the airway pressure cannot be measured in real time during jet ventilation. SEEKflex does not contain an anchoring device such as a balloon or basket which could keep the catheter in a stable position and prevent mucosa injury. However, in our study we did not find that the SEEKflex kinked or mucosa injury occurred during jet ventilation. It was likely due to nasal intubation method of the SEEKflex, which contributed to its fixation. The SEEKflex had four rows of side holes which also decreased the pressure delivered at the distal end and minimized the SEEKflex kink during jet ventilation. The baseline SpO2 in our patient cohort was over 90%, which was in the relatively normal range, our results could not represent oxygenation or ventilatory profiles of patients with poor baseline oxygen saturation. Further clinical studies are warranted for the effectiveness and safety of subglottic jet ventilation in patients experienced poor baseline oxygen saturation. Since only the SEEKflex was used in this study, no comparison with other subglottic devices was performed; their use might lead to different ventilation outcomes.
In conclusion, our study demonstrates that subglottic jet ventilation via SEEKflex in patients receiving FB under moderate to deep sedation significantly reduced the incidence of hypoxia when compared with supraglottic jet ventilation via WNJ. Complications related to jet ventilation and sedation during the use of subglottic jet ventilation were easily managed and tolerable. Results suggested that subglottic jet ventilation via the SEEKflex may be a preferable approach for patients receiving FB.
Supplementary Information
Acknowledgements
We would like to appreciate the patients for their participation in the study.
Abbreviations
- FB
flexible bronchoscopy
- WNJ
Wei nasal jet tube
- SEEKflex
Safe Easy Endotracheal Kit-flexible
- ASA
American Society of Anaesthesiologists
- BMI
body mass index
- SpO2
oxygen saturation measured by pulse oximetry
- MOAA/S
Modified Observer Assessment of Alertness/Sedation Scale
- SIVA
World Society of Intravenous Anesthesia
- RR
relative risk
- CI
confidence interval
- SD
standard deviation
- IQR
interquartile range
Authors’ contributions
Concept/design: Yaohua Yu, Zui Zou, Chunlan Lin, Chenglong Zhu; Study conduct: Chunlan Lin, Liangqing Lin, Qinghua Wu, Huan Chen, Tingting Zou, Hai Chen; Data analysis: Chenglong Zhu, Liangqing Lin; Supervision: Yaohua Yu, Zui Zou; Drafting of the manuscript: Chunlan Lin, Chenglong Zhu; Critical revision of the manuscript for important intellectual content: all authors.
Funding
This work was supported by Fujian Provincial Natural Science Funding (2023J011729).
Data availability
The data can be available from the principal investigator on reasonable request.
Declarations
Ethics approval and consent to participate
This study was approved by the Ethics Committee of The First Hospital of Putian (2022-049). The trial was registered before patient enrollment in the Chinese Clinical Trial Registry on September 26, 2023 (ChiCTR2300076139, principal investigator Yaohua YU).Written informed consents were obtained from all patients. The clinical trial was conducted in accordance with the Declaration of Helsinki. This manuscript adheres to the CONSORT guidelines.
Competing interests
The authors declare no competing interests.
Footnotes
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Chunlan Lin and Chenglong Zhu contributed equally to this work.
Contributor Information
Zui Zou, Email: zouzui@smmu.edu.cn.
Yaohua Yu, Email: yyh.8@163.com.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Data Availability Statement
The data can be available from the principal investigator on reasonable request.