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From the Department of Anesthesia, University College Hospital, Galway, Ireland.
Dr. Brian O’Brien, Department of Intensive Care Medicine, The Alfred Hospital, Commercial Rd., Prahran 3181, Victoria, Australia. Phone: 613-92763036; Fax: 613-92763780; E-mail: drbobrien{at}hotmail.com
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Abstract |
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Methods: In a prospective randomized trial, we used a standardized technique of anesthesia and of laryngeal mask insertion in 126 consecutive day-case patients. Postoperatively, on eye opening, the masks were removed either inflated (Group A) or deflated (Group B) and examined for blood by a blinded observer. Episodes of coughing, gagging, laryngospasm, hiccups and retching, and symptoms of sore throat and hoarseness were recorded by the same observer.
Results: Demographics were similar. Bloodstaining occurred in 21% of patients in Group A (n = 63) vs 13% in Group B (n = 63; P = 0.23); the incidence of sore throat was identical (19%). Group A experienced more hoarseness (22% vs 9%; P = 0.05). Overall airway complications did not differ between groups (19% vs 11%; P = 0.21).
Conclusion: We conclude that removal of the laryngeal mask airway inflated does not reduce the incidence of sore throat, pharyngeal morbidity or airway complications.
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Introduction |
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Methods |
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= 0.05), with a power of 80%. Patients were excluded from the analysis if more than one attempt was required to insert the LMA, there was history of recent sore throat or of respiratory infection. Premedication was not given, anticholinergic agents were avoided and anesthetic management was standardized. Standard monitors of electrocardiogram, pulse oximetery, capnography and non-invasive blood pressure were applied prior to induction of anesthesia. Patients were preoxygenated for three minutes. Anesthesia was induced with propofol 2.5 mg·kg–1 and fentanyl 1.5 µg·kg–1 followed by N2O and sevoflurane in oxygen. All patients had an LMA inserted using a standardized approach (with the posterior aspect of the LMA against the hard palate and a single twisting movement) with the cuff partly inflated (10 mL in size 3, 20 mL in size 4) and lubricant on the lateral and posterior aspects. Size 3 masks were used in women and size 4 masks in men. The masks were assessed clinically by easy ventilation of the lungs without a significant leak at 15 cm H2O and by a non-obstructed capnography trace. Masks were placed by two experienced anesthesiologists unaware of patient group (this was only decided at the conclusion of the procedure by opening of sealed envelopes). No attempt was made to ventilate the patients’ lungs by face mask or to instrument the airway with suction catheters at any time during the anesthetic. Diclofenac 100 mg pr was administered with the patients’ prior consent and the wound infiltrated with local anesthetic where appropriate, to provide postoperative analgesia. Intraoperative airway complications were recorded, the intraoperative period being considered to end when the sevoflurane and nitrous oxide were turned off at the conclusion of surgery.
Group A patients (n = 63) had their LMAs removed inflated, and Group B theirs removed deflated (n = 63). LMAs were removed by the attending anesthesiologist when the patient was able to open his/her mouth to command and were inspected by a blinded observer (the recovery room nurse) for the presence of blood. All masks were presented inflated for examination. The same nurse observer then asked the patient about the symptoms of sore throat and hoarseness and recorded episodes of hiccup, retching, laryngospasm and coughing/gagging while in the recovery room. Nurses were randomly allocated to patients, as is our usual hospital practice. Continuous data were analyzed using student’s t test; frequency data were analyzed using the Chi square test with 95% confidence intervals (CI). A P value < 0.05 was considered statistically significant.
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Results |
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). Intraoperative airway complications of hiccupping, coughing or gagging were seen in 13 (10%) patients. Five (8%) patients in Group A had intraoperative airway complications (i.e., three episodes of hiccupping and two of gagging and coughing) as did eight (12%) patients in Group B (six episodes of coughing and gagging, and two of hiccups). These differences were not statistically significant (P = 0.38).
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). Thirteen (21%) patients had blood stained masks in Group B (n = 63) vs eight (13%) patients in Group A (n = 63; P = 0.23, 95% CI, 0.04–0.20). The incidence of sore throat was the same in both groups (19%). There was an increased incidence of hoarseness in Group A i.e., 14 (22%) vs six (9%), (P = 0.05, 95% CI, 0.01–0.25).
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Discussion |
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Our protocol involved the use of LMAs one size smaller than recommended by a variety of investigators, as discussed in a recent review.2 However, as those authors observed, "the size 3 mask seems to be used frequently in females and the size 4 in males. The reasons for this practice are not clear". This remains more common practice in our institution, although increasingly the larger sized LMAs are now being used. For the purposes of the study we chose to use the more familiar, smaller sized masks, however.
Whilst initially it was recommended that the LMA be deflated prior to removal, subsequent guidelines suggested that the device be removed with the cuff moderately inflated "to aid more complete removal of salivary secretions".6 It is indeed established that a greater quantity of secretions is thus removed;3 however it appears from our findings that no clinical benefit accrues form this approach. This is in keeping with the suggestion of Deakin and colleagues3 that while "the difference in the mass of secretions removed is statistically significant, we do not believe (it) is likely to be clinically significant". We have found the patient outcome to be similar and suggest that the decision whether to remove the LMA inflated or deflated is not clinically important, as airway and laryngopharyngeal morbidity are uncommon, and appear to be unaffected by the decision.
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Footnotes |
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Revision received July 10, 2002. Accepted for publication April 11, 2002.
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References |
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2 Asai T, Brimacombe J. Cuff volume and size selection with the laryngeal mask. Anaesthesia 2000; 55: 1179–84.[Medline]
3 Deakin CD, Diprose P, Majumdar R, Pulletz M. An investigation into the quantity of secretions removed by inflated and deflated laryngeal mask airways. Anaesthesia 2000; 55: 478–80.[Medline]
4 Brimacombe J, Holyoake L, Keller C, et al. Emergence characteristics and postoperative laryngopharyngeal morbidity with the laryngeal mask airway: a comparison of high versus low initial cuff volume. Anaesthesia 2000; 55: 338–43.[Medline]
5 Keller C, Sparr HJ, Brimacombe JR. Laryngeal mask lubrication. A comparative study of saline versus 2% lignocaine gel with cuff pressure control. Anaesthesia 1997; 52: 592–602.[Medline]
6 Brimacombe JR, Brain AIJ, Berry AM. The Laryngeal Mask Airway Instruction Manual. 4th ed. London: Intavent Research Ltd., 1999.
This article has been cited by other articles:
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  Y. H. Shim, C. S. Shin, C. H. Chang, and Y.-S. Shin Optimal End-Tidal Sevoflurane Concentration for the Removal of the Laryngeal Mask Airway in Anesthetized Adults Anesth. Analg., October 1, 2005; 101(4): 1034 - 1037. [Abstract] [Full Text] [PDF]
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