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The effect of deep vs. awake extubation on respiratory complications in high-risk children undergoing adenotonsillectomy: A randomised controlled trial

von Ungern-Sternberg, Britta S.; Davies, Kylie; Hegarty, Mary; Erb, Thomas O.; Habre, Walid

European Journal of Anaesthesiology: September 2013 - Volume 30 - Issue 9 - p 529–536
doi: 10.1097/EJA.0b013e32835df608
Airway management
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CONTEXT There is ongoing debate regarding the optimal timing for tracheal extubation in children at increased risk of perioperative respiratory adverse events, particularly following adenotonsillectomy.

OBJECTIVE To assess the occurrence of perioperative respiratory adverse events in children undergoing elective adenotonsillectomy extubated under deep anaesthesia or when fully awake.

DESIGN Prospective, randomised controlled trial.

SETTING Tertiary paediatric hospital.

PATIENTS One hundred children (<16 years), with at least one risk factor for perioperative respiratory adverse events (current or recent upper respiratory tract infection in the past 2 weeks, eczema, wheezing in the past 12 months, dry nocturnal cough, wheezing on exercise, family history of asthma, eczema or hay fever as well as passive smoking).

INTERVENTION Deep or awake extubation.

MAIN OUTCOME MEASURE The occurrence of perioperative respiratory adverse events (laryngospasm, bronchospasm, persistent coughing, airway obstruction, desaturation <95%).

RESULTS There were no differences between the two groups with regard to age, medical and surgical parameters. The overall incidence of complications did not differ between the two groups; tracheal extubation in fully awake children was associated with a greater incidence of persistent coughing (60 vs. 35%, P = 0.028), whereas the incidence of airway obstruction relieved by simple airway manoeuvres in children extubated while deeply anaesthetised was greater (26 vs. 8%, P = 0.03). There was no difference in the incidence of oxygen desaturation lasting more than 10 s.

CONCLUSION There was no difference in the overall incidence of perioperative respiratory adverse events. Both extubation techniques may be used in high-risk children undergoing adenotonsillectomy provided that the child is monitored closely in the postoperative period.

TRIAL REGISTRATION Australian New Zealand Clinical Trials Registry: ACTRN12609000387224.

From the Department of Anaesthesia and Pain Management, Princess Margaret Hospital for Children (BSU-S, KD, MH), the School of Medicine and Pharmacology, University of Western Australia, Perth, Australia (BSU-S), the Division of Anaesthesia, University Children's Hospital, Basel (TOE) and the Paediatric Anaesthesia Unit, Geneva Children's Hospital, University Hospitals of Geneva, Geneva, Switzerland (WH)

Correspondence to Professor Britta S. von Ungern-Sternberg, Department of Anaesthesia, Princess Margaret Hospital for Children, Roberts Road, Subiaco, WA 6008, Australia E-mail: britta.regli-vonungern@health.wa.gov.au

Published online 21 January 2013

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Introduction

Adenotonsillectomy is the most frequently performed surgical procedure in children and is associated with a high incidence of perioperative respiratory adverse events.1–3 Although these respiratory complications may occur at all stages of anaesthesia, they are most frequently observed following tracheal extubation and in the subsequent recovery period.1 They may lead to serious sequelae, in particular an increased incidence of laryngospasm. This is further increased in children with airway reactivity, a medical condition often encountered in children scheduled for adenotonsillectomy.1 Considering that tracheal extubation is a critical event during emergence from anaesthesia, and that complications arising at extubation may dictate the immediate postoperative course, we wished to investigate whether performing tracheal extubation in deeply anaesthetised children compared with extubation in fully awake children would affect the incidence of perioperative respiratory adverse events.

Common teaching practice advocates awake extubation following adenotonsillectomy; there are only a few studies that have investigated the effect of extubation techniques on the incidence of respiratory adverse events following adenotonsillectomy. Some authors have found no difference in the incidence of laryngospasm and breath holding following awake vs. deep extubation,4,5 whereas others have promoted a ‘no touch’ technique to enable tracheal extubation in the fully awake child with the aim of preventing laryngospasm.6 Authors advocating the use of deep extubation suggest that the child is less likely to strain and cough during extubation and this might consequently reduce adverse events such as bronchospasm and laryngospasm. Conversely, those promoting awake extubation argue that post-tonsillectomy patients have potentially soiled airways and that the return of airway reflexes will protect against the development of perioperative respiratory adverse events. Both techniques are currently practised and the choice is often based on the anaesthesiologist's preference or on institutional practice. From current evidence, it would appear that in healthy children, the timing of extubation during emergence from anaesthesia does not appear to alter the clinical outcome.5

We recently identified, in a large prospective cohort study in our institution, a population at a particularly high risk for perioperative respiratory adverse events.1 Moreover, on closer examination of the risk factors in our cohort, the timing of extubation appeared to affect the incidence of laryngospasm and severe coughing. We, therefore, designed a prospective randomised controlled trial in order to compare the incidence of laryngospasm, bronchospasm, severe coughing, desaturation less than 95%, airway obstruction and/or stridor following tracheal extubation in deeply anaesthetised vs. fully awake children at increased risk following adenotonsillectomy.

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Patients and methods

Ethics approval for this study (1599/EP) was provided by the institutional Ethics Committee (Princess Margaret Hospital for Children) on 20 November 2008. The study was registered with the Australian New Zealand Clinical Trials Registry (15/06/2009) prior to the inclusion of study participants: ACTRN12609000387224. Following parental written informed consent, 100 children (0 to 16 years) undergoing elective adenotonsillectomy with one or more risk factors for perioperative respiratory adverse events (cold or flu in the previous 2 weeks, wheezing on more than three occasions in the previous 12 months, wheezing on exercise, nocturnal dry cough, current or past eczema, ≥2 family members with asthma, ≥2 family members with eczema, ≥2 family members with hay fever, mother or mother and father smoking) were included in the study.1 Eligibility for inclusion in the study was determined via a modified ISAAC (International Study of Asthma and Allergies in Childhood) questionnaire administered by an anaesthesia research nurse.1 Patients with known cardiac disease, airway or thoracic malformations, need for premedication (for example midazolam, clonidine, ketamine) or a contraindication for deep extubation (such as gastro-oesophageal reflux) were excluded from participation in the study.

Demographics and patient characteristics, including the presence/absence of obstructive sleep apnoea syndrome (OSAS), were recorded for all patients. OSAS was graded according to our institutional clinical scoring parameters.7 Following inclusion into the study protocol, the children were randomly assigned to either an ‘awake’ group or ‘deep’ group by computer-generated block randomisation, which was concealed in a closed envelope until the patient was in the induction room. Children were randomised following the induction of anaesthesia and the attending anaesthesiologist and data recorder in theatre were then aware of the study arm the patient was assigned to. The post anaesthesia care unit (PACU) nurse and the parents remained blinded to the study arm throughout the perioperative period. Any respiratory adverse events were recorded by the attending anaesthesiologist or the data recorder in theatre during anaesthesia and by the PACU nurse in the recovery period.

Routine anaesthesia monitoring included ECG, noninvasive blood pressure, capnography and pulse oximetry. Induction of anaesthesia was performed as deemed appropriate by the attending anaesthesiologist using either inhalational induction with sevoflurane or intravenous induction with propofol (>3 mg kg−1). All children were intubated with a cuffed tracheal tube. Cuff pressure was routinely measured and adjusted to 15 to 20 cmH2O. Maintenance was standardised to sevoflurane in nitrous oxide, while the use of muscle relaxants, selective NSAIDs and opioid analgesia were chosen and dosed by the attending anaesthesiologist. All children received antiemetic prophylaxis with dexamethasone (0.15 mg kg−1 to a maximum of 8 mg) and ondansetron (0.15 mg kg−1 to a maximum of 8 mg). One experienced ENT surgeon, who used bipolar diathermy as his surgical technique, performed the majority of surgeries.

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Procedure for tracheal extubation

Tracheal extubation in the ‘awake’ group was undertaken when the child had demonstrated facial grimacing, adequate tidal volumes and respiratory rate, coughing with an open mouth or opening of their eyes and purposeful movements. Extubation in the ‘deep’ group was undertaken when the end-tidal sevoflurane level was greater than 1 minimum alveolar concentration and the child was deemed to be in the surgical plane of anaesthesia (central, equal pupils and regular respirations). All children were placed on 100% oxygen prior to extubation. None of the children received topical or intravenous lidocaine. All patients were transported in the lateral position to the PACU by the anaesthesiologist after ensuring that they were able to maintain adequate airway patency. The attending anaesthesiologist remained with the patient until satisfied that the patient had a patent airway and was responsive. Simple airway manoeuvres, such as chin-lift, were performed by the anaesthesiologist or the PACU nurse if airway obstruction was apparent, with or without associated desaturations. Oxygen saturation was measured continuously until the patients were discharged from the PACU. All children received oxygen on arrival to the PACU until completely awake. They were then placed in room air, unless the saturation was less than 95% when supplemental oxygen was administered.

Oxygen saturation was recorded when the patients were calm and the pulse oximeter showed consistent readings with no movement artefact. The lowest measured oxygen saturation values were recorded 10 min before tracheal extubation and at 1, 2, 3, 5, 7, 10, 15, 20, 25 and 30 min after tracheal extubation. Episodes of laryngospasm, bronchospasm, desaturation less than 95%, airway obstruction, severe coughing or postoperative stridor, as well as all airway interventions, were recorded. We defined laryngospasm as complete airway obstruction with associated muscle rigidity of the abdominal and chest walls.1 Bronchospasm was defined as increased respiratory effort, particularly during expiration, and wheeze on auscultation. We defined airway obstruction as the presence of partial airway obstruction in combination with a snoring noise and respiratory efforts. Coughing was defined as a series of pronounced, persistent severe coughs lasting more than 10 s. The primary outcome measure for analysis was defined as an oxygen saturation less than 95% for more than 10 s. However, as oxygen saturation is recorded continuously in the recovery area in line with our institutional guidelines, we also captured shorter episodes of desaturation. Any treatment needed in response to respiratory adverse events was recorded.

All children and parents were interviewed on the ward or at home (via telephone) during the first postoperative day regarding the level of pain and the presence or absence of respiratory adverse events by an anaesthesia research nurse. Depending on the patient's age, a visual analogue score (1 to 10), Faces Pain Scale (revised) or Wong Baker Faces chart was used. Parents were asked about general breathing problems including severe snoring (defined as severe persistent snoring >10 s), breath holding (defined as apnoea >10 s), difficulty breathing (any evidence of increased work of breathing) and hoarse voice (defined as a change of the child's normal voice noticed by the parent). As this information was acquired via the telephone from the parents, potential problems were summarised as general breathing problems.

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Statistical analysis

The occurrence of one or more postoperative respiratory adverse events was the primary outcome for the analysis. The occurrence of one or more respiratory complications in the perioperative period was regarded as a complication, independent of the number or type of complications. A two-group χ2 test with a 0.05 two-sided significance level had an 80% power to detect the difference between the ‘awake’ group (proportion 0.35) and ‘deep’ group (proportion 0.1; odds ratio 0.206), when the sample size of each group was 43. To allow for protocol violations, seven additional patients were added into each group. Sample size calculations were performed using the nQuery Advisor 4.0 software (Statistical Solutions, Boston, Massachusetts, USA). Data were analysed using a two-group χ2 test. Data are displayed as number (proportion) or median (range) as appropriate. Results were analysed using SigmaStat for Windows (Version 3.11; Systat Software, San Jose, California, USA).

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Results

One hundred children were included in this study (see Fig. 1). There were no dropouts or protocol violations and complete datasets were available for all children. Demographic data and distribution of risk factors are presented in Table 1. Two-thirds of the children were the American Society of Anesthesiologists physical status 2, with the most common cause their history of OSAS. Few children had had a sleep study prior to surgery. Based on clinical OSAS parameters,7 there was a tendency to more severe OSA grade, as well as a higher incidence of upper respiratory tract infection, a history of passive smoking and wheezing on exercise in children randomised to the deep group.

Figure

Figure

Table 1

Table 1

There were similar proportions of inhalational and intravenous induction between the groups (14 vs. 36 in the ‘awake’ group and 13 vs. 37 in the ‘deep’ group, respectively). All children received intraoperative opioids (fentanyl 1 to 2 μg kg−1, morphine 0.05 to 0.1 mg kg−1 or pethidine 0.5 to 1 mg kg−1), with no difference in opioid use between the two groups. Forty-two patients in the ‘awake’ group received fentanyl and morphine, whereas eight patients received pethidine. Forty-one patients in the ‘deep’ group received fentanyl and morphine, whereas nine patients received pethidine. Average fentanyl usage in both groups was 1.4 μg kg−1. The majority of patients did not receive muscle relaxants, with no difference between the groups.

The rates of severe perioperative respiratory adverse events (laryngospasm and bronchospasm) were very low in both groups (Table 2). At emergence from anaesthesia, the children extubated awake showed significantly more severe coughing when compared with the children who were extubated deep (58 vs. 8%, P <0.001). There were no differences in the incidence of respiratory adverse events between the two groups during their stay in PACU. If the data were combined for emergence and PACU, the children extubated awake had a higher incidence of persistent coughing (60 vs. 35%, P = 0.028), whereas the children who were extubated deep had more episodes of partial airway obstruction (26 vs. 8%, P = 0.033) relieved by chin lift or jaw thrust. However, whereas there was no difference in the number of episodes of oxygen desaturation lasting more than 10 s between the groups (24% ‘deep’ group vs. 36% ‘awake’ group, P = 0.28), shorter desaturations (SpO2 <95% <10 s) tended to be more common and of longer duration in the awake group (see Fig. 2).

Table 2

Table 2

Figure

Figure

The assessment of overall pain on day 1, breathing problems within the first 24 h and hoarse voice reported during the postanaesthetic interview are reported in Table 3. The children extubated deep had a lower incidence of hoarse voice as compared with the children who were extubated awake (26 vs. 48%, P = 0.038).

Table 3

Table 3

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Discussion

The overall incidence of laryngospasm and bronchospasm following tracheal extubation in children at high risk for respiratory complications who underwent adenotonsillectomy was very low, demonstrating the general safety of both the awake and deep extubation techniques. However, children who had their trachea extubated while they were awake had a higher incidence of severe coughing at emergence and a higher rate of hoarse voice on the first postoperative day. Although there was no difference in the number of episodes of oxygen desaturation between the groups (24% ‘deep’ group vs. 36% ‘awake’ group, P = 0.28), the episodes tended to be more common and of longer duration in the awake group. In contrast, the children who were extubated while deeply anaesthetised showed an overall higher incidence of partial airway obstruction, when the assessment time of emergence of anaesthesia and PACU were combined. However, there was no evidence for an increased risk for oxygen desaturation following either technique.

One limitation of this study is that the anaesthesia technique was not completely standardised. We did not specify the doses of opioids, and the attending anaesthetist could adjust the dose of opioid as deemed clinically appropriate, for example reducing the dose in younger children and in children with moderate or severe OSAS. However, both groups received similar intraoperative opioid agents and doses. It is, therefore, unlikely that the type of agent or the dose of opioids used influenced the incidence of coughing in the awake group. Similarly, the use of muscle relaxants was at the discretion of the attending anaesthesiologist. The majority of patients did not receive muscle relaxants (with no difference between the groups) as adenotonsillectomy surgery commonly takes only 10 to 15 min in our institution, by which time muscle relaxants would not be reversible (sugammadex is not routinely used in our hospital).

In this study, we included children with known susceptibility for reactive airways,8–10 who have previously been demonstrated to be at increased risk for the occurrence of perioperative respiratory adverse events.1 We, therefore, expected to observe a higher incidence of postoperative respiratory complications in our study population.6 Moreover, it has been established that ENT surgery, in particular adenotonsillectomy, is associated with a significantly higher incidence of respiratory adverse events.2,3 The investigation of a specific tracheal extubation technique for this type of surgery in high-risk children may be beneficial in establishing evidence-based guidelines that can be used to inform clinical practice. Although the overall incidence of postoperative respiratory complications observed in this study appeared to be higher than that previously reported,1 bronchospasm and laryngospasm were rarely encountered. This may reflect the fact that anaesthesia was predominantly provided by specialist consultant anaesthesiologists, a factor that was demonstrated to be protective against respiratory adverse events in previous studies.1,2 However, this study was not powered sufficiently to detect a difference in the incidence of laryngospasm or bronchospasm independently.

Children with a history suggestive of OSAS or confirmed OSAS are known to have an increased incidence of respiratory adverse events following adenotonsillectomy, in particular airway obstruction and oxygen desaturation.11–13 Although a large number of children in this study had a clinical history suggestive of OSAS, there was no difference between the two groups. However, the children in the ‘deep’ group demonstrated a tendency towards more severe grades of OSAS. Therefore, it is unlikely that the difference in results obtained in this study was affected by the presence of OSA. Nevertheless, the potential effect of intraoperative doses of opioids on the measured outcome cannot be dismissed, particularly as it has been demonstrated that reducing the dose of intraoperative morphine may decrease the incidence of respiratory adverse events.14

Episodes of severe coughing are often reported following tracheal extubation in a fully awake child.1 When it occurs, coughing may affect surgical haemostasis and potentially increase postoperative bleeding. The timing of tracheal extubation is a matter of controversy among paediatric anaesthesiologists. Whereas supporters of deep tracheal extubation may argue for greater efficiency and quicker room turnover using this technique, those in favour of awake extubation stress the importance of the perioperative set-up, including PACU facilities, in their decision-making process. It has to be pointed out that in our study, the patients in the ‘deep’ group were extubated during the surgical stage of anaesthesia after ensuring adequate spontaneous ventilation. However, the attending anaesthesiologist stayed with the patient until adequate airway control was established. Additionally, our PACU is staffed with experienced nurses who manage patients on a one-to-one basis at all times, in accordance with our institutional guidelines. This allowed for good postoperative supervision of the patient and the immediate use of simple airway manoeuvres in cases of airway obstruction. However, if deep extubation is practised in a setting with lower acuity postoperative care, then the higher incidence of partial airway obstruction we observed might be associated with an increased risk of oxygen desaturation.

In this study, the children who were extubated awake showed a strong tendency towards more episodes and longer durations of oxygen desaturation, although this was not significant. This finding is in line with the results of two previous studies in healthy children that reported lower oxygen saturation values immediately after extubation when compared with children extubated deep.4,5 This is supported by evidence demonstrating that the degree of wakefulness does not necessarily correlate with the occurrence of oxygen desaturation.15

The incidence of hoarseness was higher in the children who were extubated awake. Our results are in accordance with previous studies suggesting that higher rates of postoperative hoarseness in children extubated awake can be attributed to the greater incidence of persistent coughing in the perioperative period.16 Accordingly, and in line with current literature, we found no differences in postoperative stridor or postoperative pain5 between the two groups. This would suggest that surgery-related pain was not a factor in the causation of hoarseness and did not bias our results.

Awake extubation after adenotonsillectomy is still taught as the standard technique in many institutions. There is no doubt that awake extubation remains the technique of choice for the child with a difficult airway or in children at increased risk of aspiration of gastric contents. However, in healthy children, or children with a high risk of postoperative respiratory adverse events, our study demonstrates that deep extubation is comparable with awake extubation with regard to the incidence of such events in a tertiary paediatric centre.4,5

This study only assessed the impact of deep vs. awake removal of cuffed tracheal tubes. Laryngeal mask airways that are used increasingly for adenotonsillectomy in the paediatric population may have a different risk profile with regard to the timing of the removal of the airway device due to their less invasive nature. Furthermore, the use of different maintenance agents (other than sevoflurane as evaluated in this study) may also change the recovery profile.

In summary, our findings demonstrate that tracheal extubation after adenotonsillectomy is not associated with a high incidence of laryngospasm or bronchospasm, both complications that may be potentially life-threatening. Our study did show that children who had their trachea extubated awake experienced severe persistent coughing leading to a higher rate of hoarseness in the postoperative period. Conversely, children who had their trachea extubated while they were still deeply anaesthetised had a higher incidence of partial airway obstruction, as defined by the patient requiring a simple manoeuvre such as a chin lift or jaw thrust. Reassuringly, these episodes of airway obstruction were managed by means of standard airway manoeuvres and were not associated with desaturation.

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Conclusion

In conclusion, our results demonstrate that there was no overall superior extubation technique in high-risk children undergoing adenotonsillectomy. Awareness of the potential for serious respiratory problems in the postoperative period, as well as processes to recognise and prevent these complications, may be as important as the extubation technique in the management of these patients.

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Acknowledgements

Assistance with the study: the authors thank all the children and their families who participated in this study.

Financial support and sponsorship: this study was funded by the Princess Margaret Hospital Foundation, Woolworths Australia and the Department of Anaesthesia and Pain Management, Princess Margaret Hospital for Children.

Conflicts of interest: none declared.

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References

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