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dème laryngé associé au masque laryngé ProSealTM dans une infection des voies respiratoires supérieures]
From the Department of Anesthesiology, Tan Tock Seng Hospital, Singapore, Republic of Singapore.
Address correspondence to: Dr. Ki Jinn Chin, Department of Anesthesiology, Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, Singapore 308433, Republic of Singapore. E-mail: gasgenie{at}yahoo.co.uk
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Abstract |
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Clinical features: A 55-yr-old woman had fixation of a radial fracture under general anesthesia with muscle relaxation. She developed audible wheezing 30 min after PLMA insertion. Bronchoscopic examination revealed significant vocal cord edema. Adequate ventilation was possible at increased airway pressures, and the administration of dexamethasone 4 mg iv produced clinical resolution of the stridor and airway obstruction. The patient admitted to having mild symptoms of an URTI on postoperative questioning.
Conclusion: Airway hyperreactivity secondary to the URTI is the most likely etiological factor; other possibilities include trauma from insertion and chemical irritation. Although pediatric studies suggest that the LMA-ClassicTM carries less risk than endotracheal intubation in the presence of URTI, this case report demonstrates that caution is still warranted when using supraglottic airways. The PLMA permitted effective ventilation despite increased airway resistance; nevertheless its role in patients with URTI is unclear. It is possible that the bulkier cuff design of the PLMA, compared to that of the LMA-ClassicTM, may have partly contributed to the development of edema in this setting.
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Introduction |
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Case report |
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General anesthesia was induced with propofol 170 mg iv, atracurium 30 mg iv and morphine 6 mg iv. A size 4 PLMA was inserted using the gum elastic bougie (GEB)-guided technique. 3 At laryngoscopy the oropharynx, epiglottis and vocal cords appeared normal. A bougie was passed under direct vision into the esophagus, the laryngoscope was removed and the PLMA was then inserted without difficulty. There were no significant hemodynamic changes in response to laryngoscopy or PLMA insertion. The cuff was inflated with 15 mL of air, and a gastric tube was passed easily into the stomach. Oropharyngeal leak pressure was measured at 28 cm H2O.
Anesthesia was maintained with isoflurane in 65% nitrous oxide. Pressure control ventilation was used at the following settings: respiratory rate 12, inspiratory:expiratory ratio 1:2, and peak airway pressure (Paw) 15 cm H2O. This generated tidal volumes (Vt) of 450–460 mL. End-tidal carbon dioxide (ETCO2) was maintained between 32–34 mmHg, and oxygen saturation (SpO2) at 98–99%. The operation was performed with the patient in the supine position.
Thirty minutes after PLMA insertion, Vt was observed to have fallen to 280 mL at the same Paw of 15 cm H2O. Oxygen saturation remained at 98%, but ETCO2 rose from 34–48 mmHg. Chest auscultation revealed inspiratory and expiratory wheezing. There was no other evidence of an anaphylactoid reaction. The wheezing did not improve despite salbutamol 1000 µg via metered dose inhaler into the PLMA. Meanwhile, adequate ventilation was maintained by increasing respiratory rate from 12 to 14, and Paw to 22 cm H2O, which produced a Vt of 450 mL.
A fibreoptic bronchoscope was used to investigate the cause of the wheeze. Bronchoscopic examination revealed marked edema of the aryepiglottic folds and the vocal cords, with severe narrowing of the laryngeal inlet (Figure
). The PLMA was appropriately positioned. No attempt was made to insert the bronchoscope beyond the vocal cords. Dexamethasone 4 mg iv was administered, and surgery was completed without further incident. A total of 1500 mL of crystalloid was infused perioperatively.
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The patient complained of mild throat pain post-operatively, and on interrogation, admitted to having had a slight sore throat and a mildly productive cough for two to three days prior to surgery. She denied fever, rhinitis or dyspnea. Full blood count results were normal. She remained well, and was discharged home on the second postoperative day.
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Discussion |
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Alternative etiological factors include trauma during insertion, and chemical irritation from residues on the PLMA. We clean our LMAs with an enzymatic detergent (Cidezyme®, Johnson & Johnson Medical Limited, Skipton, UK); they are then rinsed and auto-claved. Residual contamination is difficult to exclude, but the localized nature of the edema and the absence of previous reports make this an unlikely cause.
Trauma after LMA-ClassicTM insertion has been implicated in two case reports of postoperative supraglottic edema and epiglottitis.6,7 In this case however, trauma is unlikely to have been the main causative factor, as optimal positioning was achieved easily in a single insertion attempt. Only gentle laryngoscopy was required to achieve GEB insertion into the esophagus under direct vision. The use of the GEB-guided tech-nique avoided the possibility of trauma from glottic insertion (reported to occur in 6% of insertions using the digital technique).8
Could the use of a PLMA rather than an LMA-ClassicTM have contributed to the edema? Oropharyngeal leak pressure at a given cuff volume is higher with the PLMA compared to the LMA-ClassicTM.9 This should result in lower mucosal pressures and less pharyngolaryngeal morbidity if cuff volume is kept to the minimum required for an effective seal. We did not monitor cuff pressure, and it is possible that cuff inflation secondary to nitrous oxide diffusion may have progressively increased mucosal pressure. However, the initial inflation volume was low and the time course relatively short, hence it is likely that cuff pressures were still within acceptable limits.
Other factors apart from cuff pressure may influence the interaction of the PLMA with pharyngolaryngeal mucosa. Compared to the LMA-ClassicTM, the PLMA has both a deeper bowl and an additional dorsal cuff to push the ventral cuff more firmly into the periglottic tissues. We speculate that this design results in increased contact with glottic structures, especially the aryepiglottic folds. Brimacombe et al. reported a 0.4% incidence of mechanical vocal cord closure with the PLMA, and they also suggested that the PLMA’s larger distal cuff might result in more glottic compression than the LMA-ClassicTM at equivalent cuff volume.10 It is uncertain if a smaller mask size would have made a difference. The size used in this patient was appropriate by both weight-based and sex-based selection criteria, and a recent study demonstrated similar outcomes with either method.11
Parenteral dexamethasone 0.1 to 0.15 mg·kg–1 has been recommended in acute inflammatory airway obstruction.12 We could not find published data on the time to clinical onset of action following iv dexamethasone; this is likely to depend on the etiology and the severity of the inflammatory process. In this case, early treatment and the localized nature of the edema probably accounted for the rapid resolution with a lower dose. Combination therapy with nebulized epinephrine may also be useful; this produced rapid clinical resolution of stridor caused by intubation in hereditary angioedema, 13 as well as LMA-related trauma.6
Whether or not to administer a general anesthetic to a patient with symptoms of URTI is a classic dilemma. An editorial published in 1990 concluded that there was little evidence to show that anesthesia in adult patients with URTI leads to respiratory complications,14 and there have been few additions to the literature since. Nevertheless, it has clearly been shown in the pediatric population that URTI carries a higher risk of respiratory complications,4 and most anesthesiologists would exercise similar caution in adults. If a general anesthetic is required despite the presence of URTI, the evidence (again from pediatric patients) is that the use of the LMA significantly reduces risk compared to intubation.1,2 The role of the PLMA in this setting remains unclear. It should be noted though, that in this case it permitted effective ventilation without gastric distension or air leak, despite increased airway resistance.
In summary, this is the first reported case of laryngeal edema associated with PLMA insertion in an adult. It was readily treated with dexamethasone once the diagnosis had been made. The presence of URTI was undoubtedly an etiological factor; reminding us that general anesthesia in these patients should be embarked upon with caution, even when an LMA is used. The diagnostic utility of the fibreoptic bronchoscope is highlighted, and we recommend its use whenever difficulty is encountered during LMA ventilation. The PLMA is a highly effective supraglottic airway device, but further investigation is required to determine if it carries a greater risk of respiratory complications than the LMA-ClassicTM in this setting.
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Footnotes |
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Accepted for publication September 27, 2005. Revision accepted October 18, 2005.
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References |
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2 Parnis SJ, Barker DS, Van Der Walt JH. Clinical predictors of anaesthetic complications in children with respiratory tract infections. Paediatr Anaesth 2001; 11: 29–40.[Medline]
3 Howath A, Brimacombe J, Keller C, Kihara S. Gum elastic bougie-guided placement of the ProSeal LMATM laryngeal mask (Letter). Can J Anesth 2002; 49: 528–9.
4 Bordet F, Allaouchiche B, Lansiaux S, et al. Risk factors for airway complications during general anaesthesia in paediatric patients. Paediatr Anaesth 2002; 12: 762–9.[Medline]
5 Nandwani N, Raphael JH, Langton JA. Effect of an upper respiratory tract infection on upper airway reactivity. Br J Anaesth 1997; 78: 352–5.
6 Kaylie DM, Wax MK. Unilateral supraglottic edema after the use of a laryngeal mask airway. Otolaryngol Head Neck Surg 2002; 126: 583–4.[Medline]
7 McKinney B, Grigg R. Epiglottitis after anaesthesia with a laryngeal mask. Anaesth Intensive Care 1995; 23: 618–9.[Medline]
8 O’Connor CJ Jr, Stix MS, Valade DR. Glottic insertion of the ProSealTM LMA occurs in 6% of cases: a review of 627 patients. Can J Anesth 2005; 52: 199–204.
9 Keller C, Brimacombe J. Mucosal pressure and oro-pharyngeal leak pressure with the ProSeal vs laryngeal mask airway in anaesthetized paralysed patients. Br J Anaesth 2000; 85: 262–6.
10 Brimacombe J, Richardson C, Keller C, Donald S. Mechanical closure of the vocal cords with the laryngeal mask airway ProSealTM. Br J Anaesth 2002; 88: 296–7.
11 Kihara S, Brimacombe JR, Yaguchi Y, Taguchi N, Watanabe S. A comparison of sex- and weight-based ProSealTM laryngeal mask size selection criteria. Anesthesiology 2004; 101: 340–3.[Medline]
12 Hawkins DB, Crockett DM, Shum TK. Corticosteroids in airway management. Otolaryngol Head Neck Surg 1983; 91: 593–6.[Medline]
13 Hynam P. An interesting case of postoperative stridor (Letter). Anaesthesia 2003; 58: 1124.[Medline]
14 Fennelly ME, Hall GM. Anaesthesia and upper respiratory tract infections – a non-existent hazard? (Editorial). Br J Anaesth 1990; 64: 535–6.
This article has been cited by other articles:
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  M. S. Stix, C. J. O'Connor Jr, and D. R. Valade The ProSeal LMA does not cause laryngeal edema. Can J Anesth, September 1, 2006; 53(9): 961 - 963. [Full Text] [PDF]
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