In patients who present for anaesthesia with a known or anticipated difficult airway, there are associated risks of hypoxaemia, brain damage and death. In these patients, the airway is often managed most safely by performing awake tracheal intubation.1 During awake intubation, it is customary to apply local anaesthesia and sedation. The aim of sedation is to obtain a calm patient who is cooperative and can obey simple commands.
Several studies have compared the efficacy and feasibility of different sedation strategies and different methods of application of local anaesthesia for awake tracheal intubation.2–7 No previous study has examined discomfort as a primary outcome measure and most studies of awake intubation have investigated nasotracheal intubation, not orotracheal intubation. None of the studies had a long-term follow-up or dealt with possible long-term discomfort and none contained a comparison with tracheal intubation performed under general anaesthesia. The present study was designed to investigate discomfort associated with orotracheal intubation performed either in the awake patient or after induction of general anaesthesia for the same type of surgery. In order to detect possible long-term effects, we chose a longer follow-up time than reported previously.
This was a questionnaire study of patients identified retrospectively in our anaesthesia database. The patients identified were those who had undergone flexible fibreoptic tracheal intubation awake and the controls were those whose trachea had been intubated conventionally for the same operative procedure. We included only patients whose trachea had been intubated orally. Patients were identified from the database at the Department of Anaesthesia, Section for Anaesthesia for Ear, Nose and Throat surgery, Centre of Head and Orthopaedics, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark in the period 1 January 2005 to 26 January 2007. The patients were at least 18 years of age.
The patients were identified using the search criterion fibre intubation. The control patients were those who had conventional orotracheal intubation under general anaesthesia for the same type of surgery, with the same time elapsed since surgery, the same age and the same American Society of Anesthesiologists (ASA) classification. The files of all the selected patients were retrieved to confirm that the patients had undergone tracheal intubation as suggested by the database. As a part of the preanaesthetic evaluation of the patient, mouth opening, Mallampati classification, ability to protrude the mandible, range of movement in the neck, thyromental distance, history of previous airway management and the overall appearance of the patient had been assessed. If the senior anaesthetist in charge, based on these factors, determined that the patient was at risk of being difficult to intubate or difficult to ventilate by mask, it was decided to perform awake fibreoptic intubation.
Patients in the awake group were sedated to level 2 (co-operative, orientated, and tranquil) or level 3 (responding to commands only) on the Ramsay scale.8 This level of sedation was obtained by titrated doses of midazolam, remifentanil or propofol, or combinations of these drugs. The patients were able to obey commands such as ‘take a deep breath’ or ‘protrude your tongue’. The patients were breathing spontaneously and received local anaesthesia with lidocaine 10% sprayed to the mouth and oropharynx and lidocaine 4% sprayed via the fibrescope against the pharynx and the larynx. Transcricoid injection of lidocaine was used in some patients.
The questionnaire consisted of 17 questions concerning various aspects of the patients' expectations before tracheal intubation (fear of intubation, fear of anaesthesia, fear of operation and, if fear was present, which was feared most), previous experience of intubation (intubation awake or anaesthetised, recall of the procedure, discomfort, dyspnoea, pain, sense of suffocation, feeling of distress) and other complaints that were perceived to be attributable to intubation (dryness in the throat, coughing, pain in the throat, hoarseness, sleeping problems and nightmares) and a copy was sent by ordinary mail to each patient. Non-responders to the primary questionnaire were sent a reminder by post. The primary outcome measure was self-reported discomfort. Secondary outcomes were other distressing symptoms, hoarseness, sleeping problems and nightmares.
The data were entered into an Access database and transferred to a Microsoft Excel spreadsheet. Proportions were reported with 95% confidence intervals (modified Wald method) and analysed and compared by Fisher's exact test. A P value of less than 0.05 was considered to be statistically significant. The sample size calculation was based on the ability to detect a difference between 30 and 10% in the proportion of patients reporting discomfort, expecting an incidence of 30% in the patients who had undergone awake intubation.2,4,6,9 A sample size of 130 would allow the detection of that difference with a statistical power of 80% at the 5% significance level. With an estimated response rate of approximately two-thirds, we decided to include 206 patients (103 in each group).
The study was conducted in agreement with the Helsinki declaration and written informed consent was obtained from all participants. The regional ethics committee, De Videnskabsetiske komiteer I Region Hovedstaden, Kongens Vænge 2, DK-3400 Hillerød, Denmark, decided that the study was in accordance with the ethical requirements and that formal approval by the committee was unnecessary because the study was purely descriptive. The study was also approved by the Danish Data Protection Agency.
We identified 206 patients, of whom 45 were excluded because they had died during the defined study period, and two were excluded because they had undergone nasal intubation. Of the remaining 159 patients, 119 returned the questionnaire giving a 75% response rate. Nine of the answers were excluded for other reasons (lack of informed consent, information from relatives that the patient suffered from dementia and could not answer the questions, insufficient answers because the patient had not seen all pages of the questionnaire, or because the patient had subsequently undergone tracheostomy). This left answers from 110 patients for analysis – 48 intubated awake and 62 intubated under general anaesthesia. The two groups were acceptably matched for type of surgery and time since operation, but there were significant differences in duration of surgery and in the distributions of sex and ASA grade (Table 1). Additional details regarding anaesthetic management are shown in Table 2.
In both groups, patients feared the operation more than tracheal intubation or anaesthesia. In the awake group, 16.7% of patients feared tracheal intubation compared with 3.2% in the anaesthetised group (P = 0.02). In the awake group, 20.8% had recall of the procedure compared to none in the anaesthetised group (P = 0.0001). Neither the frequency of dryness nor pain in the throat differed between the groups. Seven patients (14.6%) in the awake group reported discomfort and none in the anaesthetised group (P = 0.002). There were no differences between the groups in respect of dyspnoea, pain or distress. Six patients in the awake group and one in the anaesthetised group reported a feeling of suffocation (P = 0.04). No significant difference was found with regard to post-procedure discomfort, sleeping problems or nightmares. Twenty-one percent of the patients in the awake group had recall of intubation compared with none in the anaesthetised group. Questionnaire results are shown in Tables 3–5.
We found that 15% of patients who had undergone awake tracheal intubation reported discomfort, significantly more than that in the anaesthetised group. Long-term problems were uncommon and only 21% of patients in the awake group actually recalled tracheal intubation.
The strength of this investigation is that it is a controlled study with a good match between the awake and anaesthetised patients regarding type of surgery and time since operation. A weakness is the long time between the time of surgery and completion of the questionnaire (a median of 15 months) and the poor reliability of human memory. However, this long observation period is a strength when looking for possible long-term effects. The patients were identified in a database and it would have been an advantage if all data had been recorded prospectively with questionnaires distributed shortly after the procedure. However, the fact that there is no difference in long-term effects is reassuring and supports the use of the awake approach when indicated. It is a limitation that the proportions of men and high ASA grades were larger in the awake group. The duration of surgery was also greater in that group and, taken together, these differences indicate that the awake patients had more co-morbidity. This could have biased our results. The matching was done when the questionnaires were sent out and the differences resulted from uneven response rates in the two groups. It is possible that sick patients would be less prone to report complaints related to the anaesthetic procedure. A prospective study should be conducted to avoid such confounding factors.
A review of the literature reveals varying levels of reported discomfort during awake fibreoptic intubation. The differences in these various studies could be attributed to different techniques used to score discomfort, ranging from self-reporting to indirect assessment by observation by the investigator.2,3,6,9,10 The majority of these studies deal with nasotracheal intubation. Our study showed relatively low levels of discomfort compared to earlier studies. Possible explanations for this could be improved methods, the use of the orotracheal instead of the nasotracheal route or the time span between surgery and completion of the questionnaire.
In our study, patients were most concerned with the surgical procedure itself and feared anaesthesia and intubation less. However, of those who expressed fear (n = 48), more of the awake patients than the anaesthetised patients feared the intubation (17 versus 3%, P = 0.05). This could be explained by the fact that the patients in the awake group received more detailed information regarding intubation than those in the anaesthetised group. Only 21% of patients in the awake group recalled that they had undergone awake intubation and 44% thought that intubation had occurred after induction of general anaesthesia. Kopman et al.2 reported partial recall in 9% and full recall in 5% of 267 patients who underwent awake tracheal intubation and Mongan and Culling4 found that 13% of 40 patients recalled awake orotracheal intubation. A study of 22 patients comparing sedation with different doses of remifentanil showed that 41% of patients had slight recall and 14% had clear recall.9 Rai et al.11 compared sedation with remifentanil and propofol, and found that 64% of patients in the remifentanil group had recall compared with 0% in the propofol group. Using a combination of remifentanil and propofol for conscious sedation, Cafiero et al.10 found that 85% of 20 patients had no recall, 10% had slight memories and 5% (one patient) had perfect recall.
In the present study, there were low incidences of dyspnoea, pain and distress in both groups. Patients in the awake group were more likely to have experienced a sense of suffocation (13 versus 2%; P = 0.05). The incidences of dryness of the throat (44–48%), coughing (18–29%) and pain in the throat (25–26%) were higher, but similar in both groups. Hoarseness was more common in the awake group (38 versus 18%). It is reassuring that nightmares and sleeping disorders occurred with low frequency.
Two randomised studies7,11 compared remifentanil with fentanyl/midazolam or propofol as sedatives during awake intubation and found that remifentanil provided acceptable intubating conditions and less reaction to intubation, but resulted in more recall than the alternative regimens. However, neither study could make reliable comparisons with the possible discomfort related to intubation after induction of anaesthesia or documented the frequency of long-term effects.
In conclusion, a small but significant proportion of patients reported discomfort during awake orotracheal intubation, compared to none in patients who underwent tracheal intubation after induction of general anaesthesia. There were no significant differences between groups in the occurrence of sleeping problems or nightmares. A prospective study should be conducted to confirm these findings.
The present work was supported by the Department of Anaesthesia, Centre of Head and Orthopaedics, Rigshospitalet, Copenhagen Denmark. None of the authors has any conflict of interest.
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