Abstract
BACKGROUND: Several studies have investigated postextubation complications of the positive-pressure and suctioning techniques; however, these studies yielded inconsistent results. Therefore, in this systematic review, we aimed to assess and compare the risk of complications between these techniques after extubation.
METHODS: This study was registered with the International Prospective Register of Systematic Reviews (CRD42021272068). We searched for randomized controlled trials (RCT) or observational studies that compared positive-pressure and suctioning extubation techniques in medical literature databases. Our search was conducted from the databases’ inception to July 7, 2022. The included studies were assessed for quality by using a risk of bias tool.
RESULTS: Six RCTs and 1 non-randomized controlled study were included in this systematic review (N = 1,575 subjects), wherein the positive-pressure and suctioning techniques were applied to 762 and 813 subjects, respectively. Three studies were conducted in operating rooms, and 4 studies were conducted in ICUs. Five studies were conducted among adults, and 2 studies were conducted among children or neonates. All the studies except 1 RCT showed that the positive-pressure technique tended to have a lower but not statistically different risk of complications, including desaturation, airway obstruction, pneumonia, aspiration, atelectasis, and re-intubation, than the suctioning technique. Three of the 6 RCTs were determined to have a high risk of bias and the 1 non-randomized controlled study was determined to have a serious risk of bias.
CONCLUSIONS: The positive-pressure technique tended to have a lower risk of complications than the suctioning technique. Further high-quality studies are warranted.
- Airway management
- extubation complications
- extubation technique
- positive pressure technique
- suctioning technique
- systematic review
Introduction
Generally, endotracheal extubation is a high-risk procedure.1,2 In recent years, because of the COVID-19 pandemic, attention has been focused on extubation to minimize aerosolization and droplet expulsion from patients.3 During extubation, mild-to-severe complications, including tooth damage, hypoxic encephalopathy, and death, can occur.4,5 Extubation failure is associated with a longer duration of mechanical ventilation, higher medical costs, and a higher mortality rate.6
Various extubation techniques, including a positive-pressure technique, suctioning technique, extubation in the semi-Fowler position, and extubation with sedative drugs, have been reported.7-9 The positive-pressure technique comprises application of positive pressure through the airway during cuff deflation and extubation, whereas the suctioning technique comprises the introduction of a suction catheter into an endotracheal tube and application of continuous suctioning during cuff deflation and extubation. Questionnaire surveys of ICU staff members in the United Kingdom and Argentina revealed that the suctioning technique was most frequently performed.10,11 However, some studies reported that the positive-pressure technique is superior to the suctioning technique.12,13
To the best of our knowledge, there has been no previous systematic review of studies that investigated extubation techniques. Given the inconclusive findings in the studies reported to date, this topic has remained controversial. Therefore, we conducted a systematic review of randomized controlled trials (RCT) and observational studies to assess and compare the risk of complications after extubation between the positive-pressure and suctioning techniques. The findings of this review could be meaningful to determine the optimal extubation technique for use within this high-risk medical procedure.
Methods
This study was registered with the International Prospective Register of Systematic Reviews (CRD42021272068, Centre for Reviews and Dissemination, University of York, York, UK) and is reported in accordance with PRISMA guidelines.14
Eligibility Criteria
We searched for RCTs or observational studies that (1) were published in peer-reviewed journals, (2) targeted subjects who were intubated as the study population, (3) compared positive-pressure and suctioning techniques, and (4) investigated postextubation complications as outcomes. Reviews, editorials, conference articles, comments, stand-alone abstracts, and nonhuman studies were excluded and considered to be beyond the scope of this review.
Search Strategy
The Medical Literature Analysis and Retrieval System Online (PubMed), Excerpta Medica Database (EMBASE), Cochrane Central Register of Controlled Trials, Web of Science, and Google Scholar databases were searched without language restriction from databases’ inception to July 7, 2022. The following search terms were used: (extubat* or trachea* or endotrachea* or cuff or deflat*) and (positive or pressur* or inflat* or cough) and (suction* or aspirat*). A detailed description of the search strategy for each database is provided in Appendix 1 (see the supplementary materials at http://www.rcjournal.com).
Study Selection
Two authors (KS and RI) independently conducted a comprehensive literature screening by using EndNote (Clarivate Analytics, Philadelphia, PA and London, UK) and Rayyan (Rayyan Systems Inc., Cambridge, MA). The reference lists of the included articles were also screened for additional eligible studies. In the case of discrepancies, consensus was reached through discussion with a third reviewer (MI). In cases in which it was not clear whether the study was eligible for inclusion in this review or when the study did not report sufficient data, we contacted the corresponding authors for clarification.
Data Extraction
We extracted data on the characteristics of the studies (publication year and country, study design and setting, and inclusion and exclusion criteria), participant characteristics (age, sex, and complications), interventions (positive-pressure and suctioning technique definitions), and postextubation complications (desaturation, airway obstruction, pneumonia, aspiration, atelectasis, and re-intubation).
Risk of Bias Assessment
Two of us (KS and RI) independently assessed the risk of bias in the evaluated RCTs by using the Cochrane Risk of Bias tool.15,16 The studies were rated as having a low risk of bias, some concerns with regard to bias, or a high risk of bias across the following domains: the randomization process, departures from the intended intervention, missing outcome data, outcome measurements, and selection of the reported results. The overall risk of bias was rated as high when one or more of the evaluated domains was rated as high risk and was rated as low when all domains were rated as low risk. Any disagreements were resolved through discussion. Similarly, the Cochrane Risk of Bias tool was used to assess the risk of bias of non-randomized controlled studies or observational studies.17 The overall risk of bias was rated as low risk of bias, moderate risk of bias, serious risk of bias, critical risk of bias, and no information. We used the Risk-of-Bias VISualization tool to create risk of bias plots.18
Results
Study Selection
The study selection process is summarized in Figure 1. After the screening process, 18 of the 4,267 identified studies were considered potential candidates for inclusion in the systematic review.7,10,11,19-33 Five studies were excluded because they were surveys on extubation techniques or airway management.10,11,19-21 In addition, 6 studies were excluded because they did not compare positive-pressure and suctioning techniques.22-27 A total of 7 studies, 6 RCTs7,28-32 and 1 non-randomized controlled study,33 were finally included in the systematic review.
Flow chart. RCT = randomized controlled trial.
Study Characteristics
These 7 studies included 1,575 subjects; 762 and 813 subjects were treated with the positive-pressure and suctioning techniques, respectively (Table 1). One of the studies was conducted in an operating room in Switzerland (Keller28 [N = 70, adult population]) and 2 were conducted in operating rooms in France (Guglielminotti et al29 [N = 120, pediatric population] and L’Hermite et al30 [N = 68, adult population]). The other 4 studies were conducted in ICUs in Argentina (Andreu et al31 [N = 240, adult population] and Andreu et al7 [N = 725, adult population]) and Iran (Yousefshahi et al33 [N = 252, adult population] and Farhadi et al32 [N =100, neonate population]).
Characteristics of the included studies for evaluating aspiration with a radiograph that uses contrast agents*
Interventions
With regard to the definition of the applied positive-pressure technique, the cuff was deflated and subjects were extubated immediately after manual inflation of the lungs in the studies by Keller,28 Guglielminotti et al,29 and L'Hermite et al,30 and there was no mention of a specific pressure value. In the 4 studies conducted by Yousefshahi et al,33 Andreu et al,7,31 and Farhadi et al,32 the cuff was deflated and subjects were extubated under mechanically controlled pressure (with an inspiratory pressure of 20 cm H2O and a PEEP of 15 cm H2O in the study by Yousefshahi et al,33 an inspiratory pressure of 15 cm H2O and a PEEP of 10 cm H2O in the 2 studies by Andreu et al,7,31 and a T-piece resuscitator adjusted by adjusting the PEEP valve to 5 cm H2O in the study by Farhadi et al32). With regard to the suctioning techniques, there was no difference among the studies.
Outcomes
The outcomes of the included studies are shown in Table 2.
Outcomes of the included studies
Desaturation and 
/
.
The definitions of oxygen desaturation after extubation were as follows: an 
of <92% within 5 min in the study by Guglielminotti et al,29 
of ≤92% within 10 min in the study by L'Hermite et al,30 and 
of < 90% or a 4% decrease in 
relative to the pre-extubation value within 15 min in the studies by Andreu et al.7,31 In the studies by Andreu et al,7,31 
after extubation was adjusted to be the same as that before extubation, whereas in the other studies, the 
before extubation was 1.0, with no oxygen administered after extubation. Yousefshahi et al33 did not assess oxygen desaturation but rather assessed the 
/
< 150 mm Hg at several points in time.
The pediatric study by Guglielminotti et al29 and the adult studies by Andreu et al7,31 showed a lower incidence of early desaturation in the positive-pressure technique group than in the suctioning technique group (Guglielminotti et al29 45.8% vs 65.6%, Andreu et al7,31 22.5% vs 25.0% and 20.4% vs 24.6%), whereas the adult study by L’Hermite et al30 showed a higher incidence of early desaturation in the positive-pressure technique group than in the suctioning technique group (48.5% vs 42.9%). The incidence of the 
/
< 150 mm Hg was lower in the positive-pressure technique group than in the suctioning technique group closer to the time from extubation (0% vs 4.6% at 1 h after extubation and 0% vs 6.3% at 4 h after extubation), whereas the difference almost disappeared further from the time of extubation (10.5% vs 9.8% at 12 h after extubation).
Airway Obstruction.
Andreu et al7,31 showed a lower incidence of airway obstruction in the positive-pressure technique group than in the suctioning technique group (5.8% vs 13.3%31 and 4.9% vs 5.6%7), whereas L’Hermite et al30 showed the opposite result (3.0% vs .0%).
Pneumonia.
Andreu et al7,31 also showed a slightly lower incidence of pneumonia in the positive-pressure technique group than in the suctioning technique group (2.5% vs 6.7%31 and 6.0 vs 6.7%7).
Aspiration.
Aspiration was assessed by Keller28 by using radiographs with a contrast agent, and the risk of aspiration was lower in the positive-pressure technique group than in the suctioning technique group (5.0% vs 10.0%). However, this study only included 40 subjects for this outcome and, therefore, was limited in terms of statistical power.
Atelectasis.
Farhadi et al32 assessed atelectasis in neonates by using a radiograph taken 24 h after extubation and found that the risk of atelectasis was ∼50% lower in the positive-pressure technique group than in the suctioning technique group (24.0% vs 46.0%). In this study, a radiologist and a neonatologist who were not aware of the intervention allocation made diagnoses based on the evidence of a new postextubation pulmonary collapse instead of a pre-extubation chest radiograph.
Re-intubation.
Andreu et al7,31 and Farhadi et al32 showed a higher risk of re-intubation in the positive-pressure technique group than in the suctioning technique group (Andreu et al7,31 12.5% vs 14.2% and 13.1% vs 14.2%, and Farhadi et al32 6.0% vs 20.0%), whereas L’Hermite et al30 showed no difference in the incidence (.0% vs .0%).
Risk of Bias
The risk of bias assessment is presented in Figures 2 and 3. In the overall assessment of RCTs, 3 studies (Keller,28 Guglielminotti et al,29 and L’Hermite et al30) showed a high risk of bias mainly because the allocation was not concealed until just before the participants were assigned to the intervention and because the measurement of the study outcomes was not blinded. One study (Andreu et al31) showed some concerns in that the allocation sequence was not well explained. Two studies (Andreu et al7 and Farhadi et al32) had a low risk of bias. In the overall assessment of non-randomized controlled study, 1 study (Yousefshahi et al33) showed a serious risk of bias because outcome assessors were aware of the allocation of the interventions and the primary outcome was not defined.
Risk of bias of the included randomized controlled trials.
Risk of bias of the included non-randomized controlled study.
Discussion
This systematic review summarizes the incidence of postextubation complications for the positive-pressure and suctioning techniques. All the included studies (except 1 RCT, by L’Hermite et al30) showed that the positive-pressure technique tended to have a lower risk of complications, including desaturation, airway obstruction, pneumonia, aspiration, atelectasis, and re-intubation, than the suctioning technique.
The following trends were observed. In the studies conducted among adults (Keller,28 Yousefshahi et al,33 L’Hermite et al,30 and Andreu et al7,31), only small differences in the incidence of complications were observed and the results varied from study to study. Conversely, in studies conducted among children or neonates (Guglielminotti et al29 and Farhadi et al32), there were fewer complications of early desaturation, atelectasis, and re-intubation in the positive-pressure technique group than in the suctioning technique group, and the difference between the 2 groups tended to be larger than that in the studies conducted among adults.
These trends suggest that the lung and airway protective effects of the positive-pressure technique in children or neonates are greater than those in adults. Some studies showed that endotracheal suctioning under oxygen administration can cause atelectasis,34 and the suctioning technique has a limited effect in reducing aspiration.12 In contrast, lung inflation owing to positive pressure was shown to improve atelectasis, and positive pressure itself as well as coughing caused by the inflation may prevent the aspiration of secretions on the cuff.12 Because vital capacity is small in children and neonates,35 these factors may have a greater impact in children and neonates than in adults. The trends observed in this review can be explained to some extent as described above. Future studies that compare the 2 extubation techniques are warranted and should focus on age-related differences.
In recent years, because of the unique risks associated with the COVID-19 pandemic, new techniques have been explored to minimize aerosolization and droplet expulsion from patients during extubation. Two techniques have been reported: the mask-over tube extubation technique (covering the patient’s face with a face mask with an airway filter after extubation)36 and the deep extubation technique (extubation under deep anesthesia).37 Although new extubation methods have been proposed, the comparison of conventional extubation methods provided in this systematic review is important both in its own right and for future comparisons between new and conventional extubation methods.
This study had some limitations. First, 428-30 of the 7 studies7,28-33 included in the systematic review had a high or serious risk of bias. Because 328-30 of these high or serious risk studies were conducted in the operating room, the results with regard to extubation in the operating room should be interpreted carefully. Second, although almost no difference was noted in the suctioning technique used among all studies, differences were noted in the positive-pressure technique between the operating room28-30 and ICU studies.7,31-33 Namely, as positive-pressure technique, manual inflation was used in the operating room studies28-30 and mechanical PEEP was used in the ICU studies.7,31-33. Because there have been no studies that compared differences between these positive-pressure techniques, it remains unknown whether they can be treated as the same techniques. Third, 7 studies included 1,575 subjects; however, more than half of the subjects were from the same institution.7,31 Therefore, the external validity of our results needs to be proved in future studies. Finally, although a previous study reported the efficacy of a specially designed endotracheal tube for the aspiration of subglottic secretions in ventilator-associated pneumonia,38 none of the studies included in the current systematic review mentioned the use of these endotracheal tubes. Thus, the results of our review may not be applicable to patients managed with such endotracheal tubes.
Conclusions
We summarized the currently available studies that compared postextubation complications in subjects managed with the positive-pressure and suctioning techniques. Further high-quality studies with a robust study design and large sample sizes are warranted.
Acknowledgments
We thank Professor Lic. Mauro Andreu for kindly sharing undisclosed information for the systematic review.
Footnotes
- Correspondence: Ryota Inokuchi MD, Department of Health Services Research, Faculty of Medicine, University of Tsukuba, 1-1-1 Tenno-dai, Tsukuba, Ibaraki, 305-8575, Japan. E-mail: inokuchi.ryota.ge{at}u.tsukuba.ac.jp
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
The authors have disclosed no conflicts of interest.
Supplementary material related to this paper is available at http://www.rcjournal.com.
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