Comparison of totally occlusive nasal pack, internal nasal splint, and transseptal suture technique after septoplasty in terms of immediate respiratory distress related to anesthesia and surgical complications

Transseptal Suturing Septoplasty in Elderly

Objectives: Assessing the effectiveness of transseptal suturing septoplasty in elderly individuals. Methods: The method used in this study involved the prospective separation of septoplasty candidates over 65 into 2 groups. The first group underwent nasal packing, while the transseptal suture technique was used on the second group. Postoperative pain was measured using the visual analog scale, and the effectiveness of the surgery was assessed using the Standardized Cosmesis and Health Nasal Outcomes-Obstruction scale. In addition, the patients' oxygen saturation levels were monitored using a pulse oximeter, and the results of the 2groups were compared. Results: The study included 26 patients with an average age of 66 years, ranging from 65 to 74 years. Of these patients, 13 received nasal packing, and the transseptal suture technique was used on the other 13. The results showed no statistically significant difference between the Standardized Cosmesis and Health Nasal Outcomes-Obstruction scores (P > .05). However, the oxygen saturation levels in group 1 were significantly lower, and the pain scores were significantly higher (P < .05) than those recorded for the other group. Conclusions: We concluded that transseptal suturing septoplasty is an effective, safe, and more comfortable surgical option for the elderly.

Comparison on the Effectiveness and Safety of Transseptal Suturing Versus Intranasal Splints After Septoplasty: A Systematic Review and Meta-analysis

BACKGROUND

The application of transseptal suturing as an alternative to intranasal splints in preventing postoperative complications, such as synechia, and maintaining nasal septal stability following Septoplasty, remains controversial. This meta-analysis aims to systematically compare the effectiveness and safety of transseptal suturing with intranasal splints after Septoplasty.

METHODS

A comprehensive systematic literature review based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was conducted. The review included randomized clinical trials (RCTs) identified through a database search in July 2023, comparing postoperative complications following Septoplasty with the transseptal suturing technique versus intranasal splints.

RESULTS

Eight published RCTs involving 570 participants were included in the meta-analysis. The analysis revealed no significant difference between the transseptal suturing and intranasal splint techniques following Septoplasty in postoperative complications, including postoperative hemorrhage, synechia, septal hematoma, septal perforation, local infection, crusting, and residual septal deviation.

CONCLUSIONS

Transseptal suturing can be applied following Septoplasty as an alternative to intranasal splints without increasing the rate of postoperative complications.

LEVEL OF EVIDENCE I

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

The Efficacy of Septal Quilting Sutures Versus Nasal Packing in Septoplasty

Nasal packing is the classic method adopted by many otolaryngologists to stabilize the nasal septum and decrease the occurrence of postoperative bleeding and septal hematoma after septoplasty. However, because of its associated postoperative morbidity, many surgeons started to adopt alternative methods. This study aimed to assess the outcome and benefits of septal quilting sutures in comparison to nasal packing after septoplasty. A prospective non-randomized comparative interventional study was carried out at two teaching hospitals in Mosul city from January 2020 to January 2021. A total of 60 patients who were candidates for septoplasty, were included in the study. According to the surgeon's preference; 30 patients had placement of septal quilting sutures (group A), and in the other 30 patients nasal packing was performed (group B). Patients were assessed for postoperative morbidity and early outcome in the first 24 h, 1 week and 1 month postoperatively. In the first 24 h after septoplasty, patients in group B had significantly higher levels of nasal/facial pain, headache, sleep disturbance, breathing difficulties and swallowing difficulties compared to group A (p < 0.001). Over the follow up period of 1 month, no significant differences were recorded regarding postoperative bleeding, hematoma, infection, adhesions formation and septal perforation between the two groups (p > 0.05). Septal quilting sutures technique is more favorable in the early period in terms of patient discomfort after septoplasty, better nasal block and nasal/facial pain, the absence of misery on pack removal, with minimal bleeding after surgery.

Is postoperative nasal packing after septoplasty safe? A systematic review and meta-analysis of randomized controlled studies

OBJECTIVES

To systemically review and compare post-septoplasty complications between total nasal packing and other techniques.

METHODOLOGY

We searched electronic databases (PubMed, Scopus, and Cochrane Library) and additional sources. The most recent search was on November 30th, 2020. Randomized controlled trials (RCTs) comparing adverse events after post-septoplasty nasal packing versus other techniques were included. The outcomes were adverse events, including respiratory distress, oxygen desaturation, pain severity, bleeding, hematoma, sleep disturbance, infection, crusting, epiphora, dysphagia, perforation, adhesion, and residual septal deviation.

RESULTS

There were 47 studies (4,087 participants) in this systematic review. Nasal packing was more likely to cause adverse events than other techniques. There were significant increases in respiratory distress, pain, sleep disturbance, crusting, epiphora, dysphagia, and adhesion. There were no statistically significant differences in oxygen desaturation, bleeding, hematoma, infection, perforation, and residual septal deviation. Subgroup analysis found that trans-septal suture was less likely to cause post-operative complications compared with total nasal packing.

CONCLUSION

Nasal packing after septoplasty was more likely to cause adverse events, including respiratory distress, pain, sleep disturbance, crusting, epiphora, dysphagia, and adhesion. Furthermore, there were no benefits of nasal packing in preventing bleeding, hematoma, and residual septal deviation when compared with other techniques. Routine nasal packing after septoplasty should be avoided. Trans-septal suture should be considered instead.

Efficacy of nasal septal splints for preventing complications after septoplasty: A meta-analysis

BACKGROUND

The efficacy of nasal septal splints, which are used as alternatives to nasal packs for preventing complications such as synechia and maintaining septal stability after septoplasty, remains controversial. The present meta-analysis assessed the efficacy and safety of nasal septal splints used after septoplasty.

METHODS

PubMed and Google Scholar databases were systematically searched until June 20, 2019. Randomized controlled trials or cohort or case-control studies comparing patients who received nasal septal splints with those who did not receive splints after septoplasty were included. Primary outcomes included postoperative pain, infection, bleeding, hematoma formation, synechia, and perforation. Random effects models were used to calculate risk differences and risk ratios with 95% confidence intervals (CIs).

RESULTS

Thirty-three eligible studies were included. The estimated rate of synechia was significantly lower in the splint group (0.037, 95% CI 0.024-0.056) than in the no splint group (0.087, 95% CI 0.055-0.135; P = 0.003), while visual analog scale scores for pain and the estimated rates of infection, bleeding, hematoma, and perforation were comparable between groups.

CONCLUSIONS

These findings suggest that the use of nasal septal splints as alternatives or in addition to nasal packing prevent synechia after septoplasty without increasing other complications, including pain, thus adding to evidence supporting the use of septal splints, particularly in cases where postoperative synechia is expected.

Evaluation of Safety and Efficacy for an Intranasal Airway Device in Nasal Surgery

Importance

Postoperative packing in nasal surgery often results in nasal obstruction and discomfort. Commercially available silicone intranasal airways (IAs) serve as dual-nasal airway tubes aimed at alleviating this process, but the safety and efficacy of these devices are unknown.

Objective

To evaluate the safety and efficacy of an intraoperatively placed IA device in rhinoplasty and nasal surgery.

Design, Setting, and Participants

In this retrospective record review, the medical records of patients undergoing nasal surgery with insertion of the IA at a single institution from 2012 to 2017 were reviewed. After review of over 200 patients, a questionnaire was developed to assess device efficacy.

Exposures

Use of the IA device. The IA is 12 cm long, anchored across the columella, extends distally along the nasal floor, and has a proximal external portion used for cleaning and maintaining patency. Placed intraoperatively, the device aims to support air flow postoperatively in the face of edema, hemorrhage, and packing.

Results

A total of 302 operations in 300 patients were analyzed, including primary and revision septorhinoplasty. A total of 24 (7.9%) patients self-removed or inadvertently dislodged the IA. Minor acute postoperative complications not unique to airway insertion included cellulitis in 4 (1.3%) participants and epistaxis in 6 (2%). Postoperatively, 1 (0.3%) patient developed dehiscence along transcolumellar incisions. A total of 59 patients (100% compliance) completed the efficacy questionnaire. The mean breathing score was between good and average (2.9 of 5), comfort scores between comfortable and average (2.9 of 5), and mean ease of irrigation score was between very easy and easy (1.96 of 5). The device was irrigated on average 3.57 times per day. A total of 43 (76%) particpiants had full patency or only partial obstruction, compared with 13 (24%) patients with total obstruction. In all patients, with or without obstruction, the effect lasted an average of 4 days.

Conclusions and Relevance

The device is safe and well-tolerated for maintaining patency of the nasal airway in patients undergoing rhinoplasty and nasal reconstruction without increased risk of incisional dehiscence.

Level of Evidence

4.

Comparative study of nasal septal retainer and nasal packing in patients undergoing septoplasty

PURPOSE

Nasal packing is frequently used after septoplasty and some complications caused by nasal packing are unavoidable. A nasal septal retainer has recently been developed. We evaluated the safety and clinical efficacy of the retainer in septoplasty, and the subjective symptoms of patients with the retainer were compared with Merocel nasal packing.

METHODS

A prospective, randomized, controlled study was performed in patients who had undergone septoplasty. In total, 39 patients were randomized to receive Merocel (n = 17) or the retainer (n = 22) after septoplasty. The deviation of nasal septum and nasal mucosa was evaluated by endoscopy. The clinical efficacy and subjective symptoms were compared using the visual analog scale.

RESULTS

During the packing/retaining period, the mean scores of headache, nasal obstruction, epiphora, and facial pressure in the retainer group were significantly lower than in the Merocel group (P < 0.05); the mean scores of nasal pain, nasal itching, rhinorrhea, dysphagia, and sleep disturbance in the retainer group were lower than in the Merocel group, but the difference did not reach statistical significance. On the removal of Merocel/retainer, nasal pain was significantly lower in patients with the retainer (P < 0.05). In the retainer group, the incidence of grade 1 bleeding was 45.5%, and grade 0 bleeding was 54.5%. In the Merocel group, the incidence of grade 2 bleeding was 23.5%, grade 1 was 47.1%, and grade 0 was 29.4%.

CONCLUSIONS

The nasal septal retainer is suitable for use after septoplasty with more beneficial effects than nasal packing.

Nasal silicone splints and quilting sutures using a septum stitch device following septoplasty: a prospective comparative study

PURPOSE

Although nasal splints and trans-septal sutures are preferred for septal closure following septoplasty, quilting sutures, also known as continuous mattress sutures, are technically challenging and thus time consuming. Recently, the utility of a novel stitch device was demonstrated for quilting sutures; however, whether it contributes to the technical solution and time management of septal sutures remains unclear. This study aims to quantify the time and cost of septal closure following septoplasty by comparing nasal splints with quilting sutures using the septum stitch device.

METHODS

We prospectively examined 23 patients who underwent septoplasty and assigned them to the following two groups: group 1, underwent the quilting suture for septal closure following septoplasty; group 2 underwent the nasal silicone splint method. We recorded the total operation time and surgical time for septal closure. Furthermore, we evaluated postoperative symptoms with Visual Analogue Scale (VAS) scores and compared the complication rate.

RESULTS

We observed no significant difference in the average of total operating time (P = 0.641) and the surgical time for septal closure (P = 0.886). Among postoperative symptoms, only nasal bleeding was significantly worse in group 1 on postoperative day 1 (P = 0.023). In addition, the occurrence of postoperative complications was insignificant between both groups.

CONCLUSIONS

The septum stitch facilitated safe and easy quilting suturing without significant increase of operation time.

History of intranasal splints

OBJECTIVE

Intranasal splints have long been utilised as a post-operative adjunct in septoplasty, intended to reduce the risk of adhesions and haematoma formation, and to maintain alignment during healing.

METHODS

A Medline literature review of the history and evolution of intranasal splint materials and designs was performed. Advantages and disadvantages of various splints are discussed.

RESULTS

Intranasal splints fashioned from X-ray film were first reported in 1955. Since then, a variety of materials have been utilised, including polyethylene coffee cup lids, samarium cobalt magnets and dental utility wax. Most contemporary splints are produced from silicon rubber or polytetrafluoroethylene (Teflon). Designs have varied in thickness, flexibility, shape, absorption and the inclusion of built-in airway tubes. Future directions in splint materials and designs are discussed.

CONCLUSION

Intranasal splints have steadily evolved since 1955, with numerous novel innovations. Despite their simplicity, they play an important role in nasal surgery and will continue to evolve over time.

Comparison on effectiveness of trans-septal suturing versus nasal packing after septoplasty: a systematic review and meta-analysis

This systematic review applied meta-analytic procedures to evaluate the curative effect of trans-septal suturing versus nasal packing after septoplasty. Computerized search of the published literature in PubMed, EMBASE, CENTRAL, Cochrane Database of Systematic Reviews, WANFANG, CNKI databases. Randomized trials investigating trans-septal suturing versus nasal packing following septoplasty in patients with deviated nasal septum. Adhesion, septal hematoma, bleeding, septal perforation, infection, pain, headache, or residual septal deviation per randomized patients. 19 randomized controlled trials of 1845 subjects were included. Meta-analysis showed that postoperative pain, headache, and adhesion were significantly lower in trans-septal suturing group. Nasal packing and trans-septal suturing technique appear to be equivalent with regard to postoperative bleeding, hematoma, septal perforation, infection, and residual septal deviation. Trans-septal suturing technology is not only associated with less patient pain, headache, and lower occurrence rate of adhesion after septoplasty but it also relates to higher patient satisfaction and an improved quality of life. The suturing technology can be used as a substitute for traditional nasal packing of the first-line treatment. More well-designed studies are needed to confirm the effect of trans-septal suturing following septoplasty.

A new modification of Doyle splint (Hemi-split Doyle) in rhinoplasty with alar base reduction

Patients perceive the pulling of a nasal splints as the most feared and stressful part of nasal surgery. Even the incisions made for alar base surgery can partly or entirely dehisce. So, we have been using modified Doyle silicone splints. We compared the modified Doyle silicone splints with conventional Doyle silicone splint. Included in the study were 64 patients undergoing alar base surgery together with open septorhinoplasty. Group 1 (n = 32) patients received a conventional Doyle intranasal silicone splint and group 2 (n = 32) received modified splint that we call a hemi-split Doyle splint. The pain felt by the patients during the removal of the splints was recorded according to the visual analogue scale (VAS). On days two and four postoperatively, the nasal stuffiness score (NOSE) was recorded. On day four postoperatively an intranasal examination was conducted to establish if dehiscence had occurred on the alar base incision line. In group 2, the pain scores during splints removal were significantly lower than those in group 1. Whereas no dehiscence on the alar base incision line was observed after tampon removal in group 2, the incision dehisced in eight patients in group 1. The NOSE scores on postoperative days two and four showed no difference between the groups. The hemi-split Doyle splint causes less pain during removal and particularly does not lead to dehiscence of incisions made during alar base surgery in rhinoplasty patients.

Comparing nasal packing with trans-septal suturing following septoplasty: a randomized clinical trial

It has been shown that nasal packing after septoplasty is associated with several complications. Our aim was to compare post-septoplasty nasal packing and trans-septal suturing, in terms of complications and outcome of operation. This randomized clinical trial was performed on patients with deviated nasal septum who were candidates for septoplasty. Patients were visited three times after operation (on the first 48 h, first week, and third post-operative month). Participants were checked for having common complications. Rhinomanometric evaluation was performed to measure nasal air flow and airway resistance, as indicators of operation efficacy, both prior to and after surgery. A total of 72 patients were allocated into the two trial arms. Patients in nasal pack group reported higher pain scores on the first 48 h (P < 0.001) and one week after surgery (P < 0.001). Epiphora (P = 0.028), sleep disturbance (P = 0.012), and dyspnea (P < 0.001) were also more commonly observed in patients using nasal pack. Objective evaluation of bleeding demonstrated that more severe bleeding occurred in patients with trans-septal sutures (P = 0.001). No differences were found comparing the indices of rhinomanometry between the two groups. Using trans-septal sutures after septoplasty compared to nasal packing, might be associated with lower frequencies of several specific complications and a lower rate of patients' discomfort. Nevertheless, increase in the risk of bleeding and hematoma was noted in the trans-septal suture group. No differences were observed between the nasal air flow and resistance of patients in the two groups.

Is nonabsorbable nasal packing after septoplasty essential? A meta-analysis

OBJECTIVES

Septoplasty is one of the most frequently performed rhinologic surgeries. Complications include nasal bleeding, pain, headache, septal hematoma, synechia, infection, residual septal deviation, and septal perforation. In this study, we aimed to compare complication rates among patients according to packing method.

METHODS

We performed a literature search using PubMed, Embase, and the Cochrane Library through August 2016. Our systematic review followed Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. Random effect models were used to calculate risk differences and risk ratio with 95% confidence intervals (CIs). Cases referred to the nonpacking group included patients treated with transseptal sutures or septal splints. Cases referred to as the packing group included patients treated with nonabsorbable packing such as Merocel or gauze.

RESULTS

Our search included 20 randomized controlled trials (RCTs) with a total of 1,321 subjects in the nonpacking group and 1,247 subjects in the packing group. There were no significant differences between packing methods regarding bleeding, hematoma, perforation, infection, and residual septal deviation. The risk differences of postoperative pain, headache, and postoperative synechia were -0.50 [95% CI: -0.93 to -0.07, P = .02], -0.42 [95% CI: -0.66 to -0.19, P = .0004], and -0.03 [95% CI: -0.06 to -0.01, P = .01], respectively.

CONCLUSIONS

Nonabsorbable nasal packing is no more effective than treatments without packing after septoplasty. Septal splints and transseptal sutures reduce postoperative pain, headache, and synechia.

LEVEL OF EVIDENCE

1B Laryngoscope, 127:1026-1031, 2017.

The comparison of the quality of life and intranasal edema between the patients with or without nasal packing after septoplasty

Septoplasty is one of the most common operations performed in otolaryngology and anterior nasal packing is done routinely to prevent postoperative bleeding, septal hematoma or nasal synechia. Currently, transseptal sutures have gained a broader application area, not only for preventing the complications such as septal hematoma and bleeding but also closing any accidental tears of septal mucosa and providing additional support for the cartilage pieces retained in septoplasty. We evaluated the quality of life of the patients in early postoperative period (in the first postoperative week), intranasal edema with endoscopic examination and the intranasal changes with acoustic rhinometry. We performed a prospective and randomized study with patients undergoing septoplasty without inferior turbinectomy. As packing material, there were two groups: in group A, gauze in a glove finger and in group B, Doyle splint were used, and in the additional group C, only transseptal suture with 4/0 vicryl among the cartilaginous septum was performed. The patients were invited to control examinations on the postoperative 2nd, 4th and 7th days to evaluate the scores from 1 to 5 on the questionnaire for the pain, nasal fullness, sneezing, epiphora, difficulty in swallowing and sleep disturbances. The patients were also administered an endoscopic nasal examination for the purpose of detecting the intranasal edema, and acoustic rhinometry was performed during the control examinations to detect the intranasal changes. Total occluding packing was found to cause much more frequent and higher scores of epiphora, sneezing, difficulty in swallowing, but mainly, the pain compared to in silicone packing with airway and transseptal suture only. Although the silicone packing with airway was found to be much more comfortable, it also led to sneezing and epiphora. The patients without nasal packing had more comfortable period especially in the early postoperative days (the first 4 days). However, 1 week after surgery, groups with and without nasal packing were found to be equalized on behalf of the objective and subjective parameters. As any complication was not observed due to not using nasal packing, it is thought that nasal packing usage following septoplasty is not a necessity.

Effects of polymer-based, silver nanoparticle-coated silicone splints on the nasal mucosa of rats

Infection is a serious complication after nasal packing that otolaryngologists seek to avoid. The aim of this study is to investigate the use of silver (Ag) nanoparticle, which serves as antimicrobial agents, with nasal tampons. The study design is an experimental animal model and the setting is tertiary referral center. Twenty-four rats were randomized into the following four groups: (1) control group (n = 6); (2) silicone nasal splint (SNS) group (n  =  6); (3) polypropylene-grafted polyethylene glycol (PP-g-PEG) amphiphilic graft copolymer-coated SNS group (n  =  6); and (4) Ag nanoparticle-embedded PP-g-PEG (Ag-PP-g-PEG) amphiphilic graft copolymer-coated SNS group (n  =  6). These tampons were applied to rats for 48 h, after which they were removed in a sterile manner, and the rats were sacrificed. The nasal septa of the rats were excised, and assessments of tissue changes in the nasal mucosa were compared among the groups. The removed tampons were microbiologically examined, and quantitative analyses were made. When the groups were compared microbiologically, there were no significant differences in bacterial colonization rates of coagulase-negative Staphylococcus spp. among the three groups (p = 0.519), but there was a statistically significant difference among bacterial colonization rates of Heamophilus parainfluenzae and Corynebacterium spp. (p = 0.018, p = 0.004). We found that H. parainfluenzae grew less robustly in the Ag-PP-g-PEG than the PP-g-PEG group (p = 0.017). However, we found no significant difference between the Ag-PP-g-PEG and SNS groups, or between the SNS and PP-g-PEG groups. The growth of Corynebacterium spp. did not differ significantly between the Ag-PP-g-PEG and SNS groups (p = 1.000). When Group 4 was compared with Group 2, the former showed less inflammation. Compared with other tampons, Ag-PP-g-PEG amphiphilic graft copolymer-coated silicone nasal tampons caused less microbiological colonization and inflammation. Therefore, the use of these tampons may prevent secondary infections and reduce the risk of developing complications by minimizing tissue damage.

Optimal time for intranasal splint removal after septoplasty: a prospective clinical study

To investigate the effect of intranasal splint removal time on patient comfort and possible complications after septoplasty. One hundred and nine patients who had septoplasty operations were included in this study. The patients were divided into three groups. In the 1st group (n = 36), splints were removed on the 3rd day after septoplasty; in the 2nd group (n = 36), splints were removed on the 5th day; and in the 3rd group (n = 37), splints were removed on the 7th day. Pain and nasal fullness were evaluated with visual analog scale. Synechia, perforation, hematoma, infection and hemorrhage were recorded after the removal of the splints (postoperative 1, 8 and 24 weeks). For the 1st, 2nd, and 3rd groups, respectively, pain score was 1.96, 2.67, and 2.67; and nasal fullness score was 6.23, 6.04, and 5.48. Nasal synechia was detected in two patients in the 1st group and in one patient in the 2nd group. Early hemorrhage was detected in two patients in the 1st group and one patient in the 3rd group. Infection, septal perforation and hematoma were detected in three patients in the 1st group. There was no difference in hemorrhage, hematoma, synechia and perforation rates between the three groups. There are various opinions in the literature about the ideal removal time of intranasal tampons after septoplasty, but there is no consensus on this topic. Our study shows that removal time of intranasal splints has no effect on patient comfort or possible complications.

Oral mask ventilation is more effective than face mask ventilation after nasal surgery

OBJECTIVE

To evaluate and compare the face mask (FM) and oral mask (OM) ventilation techniques during anesthesia emergence regarding tidal volume, leak volume, and difficult mask ventilation (DMV) incidence.

DESIGN

Prospective, randomized, crossover study.

SETTING

Operating room, training and research hospital.

SUBJECTS

American Society of Anesthesiologists physical status I and II adult patients scheduled for nasal surgery.

INTERVENTIONS

Patients in group FM-OM received FM ventilation first, followed by OM ventilation, and patients in group OM-FM received OM ventilation first, followed by FM ventilation, with spontaneous ventilation after deep extubation. The FM ventilation was applied with the 1-handed EC-clamp technique. The OM was placed only over the mouth, and the 1-handed EC-clamp technique was used again. A child's size FM was used for the OM ventilation technique, the mask was rotated, and the inferior part of the mask was placed toward the nose.

MEASUREMENTS

The leak volume (MVleak), mean airway pressure (Pmean), and expired tidal volume (TVe) were assessed with each mask technique for 3 consecutive breaths. A mask ventilation grade ≥3 was considered DMV.

MAIN RESULTS

DMV occurred more frequently during FM ventilation (75% with FM vs 8% with OM). In the FM-first sequence, the mean TVe was 249±61mL with the FM and 455±35mL with the OM (P=.0001), whereas in the OM-first sequence, it was 276±81mL with the FM and 409±37mL with the OM (P=.0001). Regardless of the order used, the OM technique significantly decreased the MVleak and increased the TVe when compared to the FM technique.

CONCLUSION

During anesthesia emergence after nasal surgery the OM may offer an effective ventilation method as it decreases the incidence of DMV and the gas leak around the mask and provides higher tidal volume delivery compared with FM ventilation.