Abstract
Background
Nasotracheal intubation (NTI) provides a good field for surgeons in patients undergoing oromaxillofacial surgery; however, NTI is often complicated by epistaxis. The aim of this study was to compare the efficacy of 4% and 6% topical cocaine solutions in reducing epistaxis during NTI.
Methods
A total of 79 patients (16–65 years old) undergoing oromaxillofacial surgery were randomly assigned to two groups treated with either 4% cocaine (n = 39) or 6% cocaine (n = 40). Topical cocaine (1 mL) was sprayed onto the selected nasal cavity prior to NTI. All intubations were performed by an expert anesthesiologist using a GlideScope. The incidence and severity of epistaxis was examined along the nasal cavity up to the nasopharynx using a fiber optic bronchoscope. The hemodynamic responses to stimuli during the peri-NTI period were also recorded.
Results
The incidence of epistaxis was 43.59% (17/39) in the 4% cocaine group and 50% (20/40) in the 6% cocaine group (p = 0.57). The severity of epistaxis did not differ between the two groups (p = 0.46). High resistance during NTI and epistaxis were closely correlated and the major bleeding sites were located at the nasopharynx. Compared with the 4% cocaine group, treatment with 6% cocaine resulted in a higher heart rate and mean arterial pressure (both p < 0.05). There was no statistically significance difference between the two groups with respect to the hemodynamic responses to NTI.
Conclusion
The spraying of either 4% or 6% topical cocaine into the nasal cavity gives comparable effects for intubation-related epistaxis. However, 6% cocaine may increase the hemodynamic responses while being sprayed. Therefore spraying with 4% topical cocaine had advantages with respect to 6% cocaine and is recommended for use prior to NTI.
Keywords
bronchoscopescocaineepistaxisfiber optic technologyintubation, intratracheal: nasal;
1. Introduction
Nasotracheal intubation (NTI) provides a good field for surgeons in patients undergoing oromaxillofacial surgery. However, tissue damage in the selected nasal cavity and the nasopharynx may render NTI difficult. Epistaxis resulting from injury to the nasal mucosa or turbinate is the most common complication of NTI.1, 2, 3 The trauma may be associated with the entire technique of NTI, including pre-intubation assessment, nasal mucosa preparation, choice of nasotracheal tube, and the method of insertion. Many methods have been described to reduce airway trauma related to NTI, such as nasal mucosa preparation,2, 4 the choice of a polyurethane nasotracheal tube,5 thermosoftening of the nasotracheal tube,6 catheter-guided techniques,7 and use of an esophageal stethoscope as an introducer.8
Good nasal mucosa preparation for NTI should include adequate lubrication, topical local anesthetics, and vasoconstrictors. To reduce epistaxis and to minimize cardiovascular stimulation, several regimens of local anesthetics combined with vasoconstrictor have been proposed, e.g., lidocaine/phenylephrine, lidocaine/epinephrine, and cocaine.4, 9, 10 Of these, cocaine is a favored choice for a local anesthetic with a native vasoconstriction effect. Topical cocaine was routinely used for nasal preparation to reduce bleeding in previously published reports.11, 12, 13 The clinical recommendation for the concentration of topical cocaine is between 4% and 10%. The aim of this study was to compare the effect of 4% and 6% cocaine solutions on the reduction of epistaxis during NTI. The adverse cardiovascular stimulation resulting from the use of cocaine and the relationship between patient characteristics and epistaxis were also investigated.
2. Methods
The study was approved by the institutional Ethics Committee of Kaohsiung Medical University Hospital (Kaohsiung City, Taiwan) and informed consent was obtained from each patient. We enrolled 80 adult patients of ASAI-II status, aged 16–65 years, with a body mass index > 18.5 kg/m2, but <30 kg/m2, who were scheduled to undergo elective oromaxillofacial surgery under general anesthesia with NTI. Patients with a history of coagulopathy, liver cirrhosis, chronic sinusitis, hypertension, diabetes, hyperthyroidism, allergy to local anesthetics, or anticipated difficult airway access were excluded from the study.
The patients were randomly allocated into two groups as follows: 80 index cards were enclosed in 80 envelopes, of which 40 cards were marked with the code for each anesthetic solution intended for the nasal spray. Code A represented the 4% cocaine solution and code B represented the 6% cocaine solution. Each patient selected an envelope on entering the operating room and received the nasal spray indicated by the code card. In the 4% cocaine group, one patient withdrew from the study due to an unanticipated difficult intubation. In the 6% cocaine group, all patients completed the trial (Fig. 1). All patients were unaware of the concentration of cocaine spray received. All NTIs were performed by an experienced anesthesiologist using a GlideScope video laryngoscope (Verathon, Bothell, WA, USA). Another anesthesiologist who was blinded to the concentration of cocaine nasal spray that the patients had received assessed the severity of epistaxis 3 minutes after NTI.
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Each patient was asked to fast for at least 8 hours prior to surgery and premedication was not used. On arrival at the operating room, the patients were monitored for heart rate, lead II electrocardiography, and noninvasive blood pressure. An otolaryngologist who was blinded to the study design examined and recorded the adenoid and nasal structure of the patients with a fiber optic bronchoscope prior to anesthesia. Each patient received midazolam 0.03 mg/kg and fentanyl 1 μg/kg during the bronchoscopy. One nostril was chosen for nasal intubation after preoperative fiber optic assessment.
Prior to induction of anesthesia, 1 mL of either 4% or 6% cocaine was prepared in a 2-mL syringe. The nasal mucosa and turbinate were hit by a 4% or 6% cocaine spray with an intranasal mucosal atomization device (Wolfe Troy Medical, Salt Lake City, UT, USA) and the patients were left for 5 minutes for the cocaine spray to take effect. In both groups, the patients were placed in the supine position with their head resting neutrally and their neck flexed over a 7 cm thick pillow. Anesthesia was induced with fentanyl 1 μg/kg, thiamylal 5 mg/kg, and rocuronium 0.6 mg/kg to facilitate NTI. A bolus of propofol 1 mg/kg was administrated 1 minute prior to NTI to blunt any intubation-induced hemodynamic fluctuations. Patients were manually ventilated with 60% oxygen for 3 minutes following loss-of-eyelash reflex. A 22-gauge catheter was inserted into either radial artery for continuous blood pressure measurement following loss of consciousness.
A preformed curved e-nasotracheal tube with a high-volume, low-pressure cuff and Murphy eye tip (Unomedical Sdn. PharmaPlast, Kedah, Malaysia) was used for NTI. The tube size was selected by sex (7 mm inner diameter for men and 6.5 mm inner diameter for women) Sevoflurane at 2.5–3.5% end-tidal concentration was administered to maintain anesthesia and the end-tidal CO2 concentration was maintained at 35–40 mmHg. The location of epistaxis was evaluated by the same anesthesiologist who had used the fiber optic bronchoscope after fixation of the nasotracheal tube. Patients were extubated in the postoperative care unit after becoming fully awake.
The primary outcome was assessed by the incidence and degree of epistaxis caused by NTI. The degree of active bleeding into the oropharyngeal space was classified into five grade scores as viewed by a GlideScope: Grade 0 (none); Grade 1 (minimal, blood-tinged on oropharynx, but nasotracheal tube not infiltrated with blood); Grade 2 (mild, the tube infiltrated with blood with less than half the height immersed); Grade 3 (moderate, the tube infiltrated with blood and greater than half the height immersed); or Grade 4 (severe, part of the tube totally immersed and invisible because of infiltration by blood). The location of epistaxis was classified as: nasopharynx; nasopharynx and turbinate; nasopharynx and posterula; and posterula alone. The degree of active bleeding flowing out from the nasal cavity was classified as: none (no bleeding); mild (slight bleeding); or moderate to severe (active bleeding).
The other parameters assessed in relation to NTI included resistance during NTI (nil, slight, apparent) and nasal structure (normal, deviated septum, turbinate hypertrophy). Hemodynamic changes (heart rate and mean arterial pressure) were documented at the following time points: preparation of anesthesia (baseline); prior to topical cocaine; 5 minutes after topical cocaine; pre-intubation; and highest value after intubation (Fig. 1).
According to Gross et al,9 the incidence of epistaxis is 62%. A minimum requirement was therefore for 37 patients to be randomly assigned to each group to demonstrate a 50% difference in the incidence of epistaxis with a power of 0.8 and a type 1 error of 0.05. In this study, we recruited 40 patients in each group to allow for study error and attrition. All data are presented as mean ± standard deviation values. Statistical analysis was carried out using a two-sample t test (numerical variables) and a Chi-square test (categorical variables). Fisher’s exact test was used for non-continuous data with a non-normal distribution. The SPSS 14.0 statistical software package (SPSS Inc., Chicago, IL, USA) was used for all analyses and values with p < 0.05 were considered statistically significant.
3. Results
There was no significant difference between the two groups (Table 1). The incidence of epistaxis was 43.6% (17/39) and 50% (20/40) for the 4% and 6% cocaine groups, respectively (p = 0.57). The severity of epistaxis did not differ significantly between the two groups with respect to either the grade of bleeding from the oropharyngeal space or from the selected nostril (Table 2). The predominant bleeding site was located in the nasopharynx, at which bleeding was found in 76.47% (13/17) of patients in the 4% cocaine group and 50% (10/20) of patients in the 6% cocaine group (Table 2).
With respect to the hemodynamics both prior to and after the administration of topical anesthetic, both the mean arterial pressure and heart rate after treatment with 6% topical cocaine were significantly increased (p = 0.04 and p = 0.01, respectively). Conversely, 4% topical cocaine only induced a slightly increased mean arterial pressure and heart rate (both p > 0.05; Table 3). However, comparing the baseline hemodynamics with those after the administration of cocaine, the hemodynamic responses to topical cocaine showed only transient effects on intubation and there was no significant difference between the two groups (Table 3).
4. Discussion
This study shows that 4% topical cocaine was comparable with 6% topical cocaine in reducing the incidence and severity of epistaxis during NTI with a GlideScope. The hemodynamic responses to topical cocaine administration were less in patients receiving 4% cocaine than in patients receiving 6% cocaine. The nasopharynx under the posterula was the major site of epistaxis as examined by a fiber optic scope. The overall incidence of epistaxis in this study was 47%, which was lower than the 62% with 4% cocaine and 63% with 3% lidocaine/0.25%phenylephrine reported previously.9 A possible explanation might be that our patients received 1 mL of cocaine nasal spray into the intubated nostril in our study, whereas in the study of Gross et al9 the patients received only 0.5 mL of nasal spray. Moreover, thermosoftening of the nasotracheal tube and GlideScope were routinely used in this study.
Topical vasoconstrictors have been used to reduce epistaxis. Higher concentrations of cocaine did not show much benefit in reducing epistaxis, supporting the view that topical anesthesia is not the only factor affecting bleeding. The recommended concentration of topical cocaine in clinical practice is 4–10% and the upper limit of cocaine dosage is 1.5 mg/kg. Topical vasoconstrictors might result in life-threatening adverse events such as arrhythmia, myocardial infarction, and even cardiac arrest.14, 15 Therefore the lowest body weight required to avoid toxic reaction in our study was 40 kg. We chose a nasal spray rather than a packing technique because spraying is easy to perform, ensures the uniform distribution of the drug on the nasal mucosa, and avoids the deep insertion of a swab stick into the nostril, which can cause patients to feel very uncomfortable. One patient in the 4% cocaine group had severe epistaxis, but this was rapidly stopped. None of the patients in this series had a severe adverse event related to topical cocaine administration.
The site of nasal trauma during NTI most frequently involved the nasopharynx. Obvious resistance is usually encountered at a depth of 10–12 cm in the nasal cavity. The depth of insertion was confirmed at the nasopharynx using examination by a fiber optic scope. Sim et al16 reported that difficult passage of the nasotracheal tube through the nasal cavity was the most significant risk factor for epistaxis during NTI (odds ratio 6.25). Impeded navigation was found in 72% (21/29) of patients with epistaxis and only 29.6% (21/71) of patients without epistaxis. This might explain why the nasopharynx was the most common site of epistaxis in this study. The inferior turbinate and adjacent septum were the most common sites of nasal damage revealed by anterior rhinoscopic examination.17 With respect to detection of the site of bleeding during NTI, the use of a flexible fiber optic bronchoscope can facilitate direct visualization of deeper structures than a rhinoscope. Minor bruising without any bleeding was found in some patients by examination of the oral cavity with the GlideScope. None of the patients in this series had significant nasal bleeding or nasal damage (i.e., septal or turbinate disruption) related to the passage of the nasotracheal tube.
There were several limitations in the study. First, there was no placebo control in the design because it is not ethical to use nasal pretreatment with saline as this is not therapeutic. Second, any patient with anticipated or unanticipated difficult intubation was excluded from the study. Furthermore, all patients underwent NTI after the induction of general anesthesia with intravenous anesthetics and neuromuscular blocking agents. Hence our result might not apply to patients with anticipated difficult airway access who have to undergo fiber optic intubation while awake. Finally, the status of the nasal cavity was observed subjectively with a fiber optic bronchoscope. For further study, an objective method may provide more accurate assessment after nasal decongestion. For example, acoustic rhinometry has been reported to be a convenient method to measure the cross sectional area and volume of nasal cavities.18
In conclusion, epistaxis is the main complication of NTI and may be lethal due to the airway becoming compromised. In this study, treatment with a 4% cocaine spray provided a similar effect to a 6% cocaine spray on the prevention of epistaxis, but with fewer hemodynamic compromises and less chance of toxicity. Therefore pretreatment of the nasal mucosa with a lower concentration (4%) of cocaine is recommended for the reduction of epistaxis during NTI.