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Table of Contents  
ORIGINAL ARTICLE
Year : 2014  |  Volume : 8  |  Issue : 3  |  Page : 291-295  

Facilitation of fiberoptic nasotracheal intubation with magnesium sulfate: A double-blind randomized study


Department of Anesthesia and PSICUD, Faculty of Medicine, Tanta University, Egypt

Date of Web Publication17-Oct-2014

Correspondence Address:
Ahmed Said Elgebaly
Department of Anaesthesia and SICUD, 43 IBN Elfard Street, Elgharbia, Tanta
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0259-1162.143111

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   Abstract 

Background: A double-blinded, prospective, and randomized study was designed to determine the efficacy and tolerability of intravenous (IV) magnesium sulfate (MgSO 4 ) to facilitate fiberoptic bronchoscopic (FOB) nasotracheal intubations.
Patients and Methods: A total of 120 patients scheduled to undergo elective awake fiberoptic nasotracheal intubation, while they were anesthetized for elective surgery were randomly allocated to one of three groups: The control Group S (n = 40) received 100 ml (50 ml 0.9% saline + 50 ml paracetamol) was infused in 10 min and direct IV 5 ml 0.9% normal saline, Group MD (n = 40): Received midazolam IV in a dose of 0.07 mg/kg in 5 ml 0.9% normal saline and 100 ml 0.9% was infused in 10 min and Group MS (n = 40): IV 45 mg/kg MgSO 4 10 min in 100 ml of 0.9% normal saline through 10 min and direct IV 5 ml 0.9% normal saline.
Results: Time required for nasotracheal intubation was significantly less in group Groups MD and MS, as compared with the control group, but not significant between the two groups. (Group MD: 9.05 + 1.95 min, Group MS 3.75 + 0.75 min and Group S 16.85 + 1.7 min). However, the number of fiberoptic intubation was significantly more in the MD and MS groups, as compared with the control group. Easy intubation (control group: 0, Group MD: 25 and Group MS: 35), moderate difficulty (control group: 5, Group MD: 12 and Group MS: 4) and difficult (control group: 35, Group MD: 3 and Group MS: 1). Procedure adverse events were significantly lower in Group MS. None of the patients in Group MS had procedure hypoxia, but it occurred in 10 patients of Group MD and 20 patients in Group S. Six patients in Group S and two in Group MD had procedure apnea whereas, none of the patients in the MS group experienced this. After medication and just before intubation heart rate and mean arterial pressure were significantly less in Groups MD and MS, as compared to the control group (Group MD: 77 + 7.7 beat/min, Group MS: 70 + 5.6 beat/min and Group S: 80 + 7.8 beat/min) (Group MD: 90 + 8.5 mmHg, Group MS: 80 + 8.1 mmHg and Group S: 105 + 10.5 mmHg). This difference however, significant between Group MD and Group MS.
Conclusion: Intravenous MgSO 4 improved awaken FOB intubation without adverse hemodynamic or respiratory effects.

Keywords: Fiberoptic, magnesium sulfate, nasotracheal intubation


How to cite this article:
Elgebaly AS, Eldabaa AA. Facilitation of fiberoptic nasotracheal intubation with magnesium sulfate: A double-blind randomized study. Anesth Essays Res 2014;8:291-5

How to cite this URL:
Elgebaly AS, Eldabaa AA. Facilitation of fiberoptic nasotracheal intubation with magnesium sulfate: A double-blind randomized study. Anesth Essays Res [serial online] 2014 [cited 2019 Aug 25];8:291-5. Available from: http://www.aeronline.org/text.asp?2014/8/3/291/143111


   Introduction Top


Although passage of a tracheal tube over a fiberoptic bronchoscope has improved the ability to manage a difficult airway, however, this technique doesn't ensure successful intubation, [1],[2] especially after topical anesthesia of the tongue and pharynx with lidocaine spray, patients cannot tolerate fiberoptic bronchoscopy with discomfort. [3] The various audits of bronchoscopic practice have reported mortality rates of 0.01-0.5% and major complication rates of 0.08-5%, respectively. [4] Most of deaths and major complications have been related to the sedative regimen used. [5],[6],[7]] This has led to an increased awareness of the need for a satisfactory sedative regimen for fiberoptic usage. [8],[9],[10]

The sedative drugs that were commonly used are opioids and benzodiazepine. [11],[12] Magnesium (Mg) plays a fundamental role in many physiological process, for example neuronal activity, muscular contraction, and control of vasomotor tone. Mg is known to possess muscle relaxing effects, mostly by reducing, acetylcholine release, and it seems to have antinociceptive and anesthetics effects. [13],[14],[15]

We hypothesized that the administration of magnesium sulfate (MgSO 4 ) could facilitate fiberoptic nasotracheal intubations.


   Patients and methods Top


This study was carried out after obtaining approval from Institutional Ethical Committee. A written informed consent was obtained from 130 patients, ages ranged between 22 and 66 years of both sex and scheduled to undergo elective awake fiberoptic nasotracheal intubation while they were anesthetized for elective surgery from January 2013 to December 2013 patients, who declined to participate or had known abnormal laryngeal structures (e.g. tumors), infectious and toxic conditions of the neck and airway, and traumatic conditions of the neck other than cervical spine fractures or dislocations were excluded from the study.

During the preparation visit, an evaluation of the anatomy of the airway was done, according to Mallampati score classification. [16] Furthermore, the data of awake intubation were explained. Peripheral cannula was inserted. Patients were classified into three groups (40 patients in each group).

  • Group S (n = 40): Received 100 ml (50 ml 0.9% saline + 50 ml paracetamol) was infused in 10 min and direct intravenous (IV) 5 ml 0.9% normal saline
  • Group MD (n = 40) : received midazolam IV in a dose of 0.07 mg/kg [17] in 5 ml 0.9% normal saline and 100 ml 0.9% was infused in 10 min
  • Group MS (n = 40) : IV 45 mg/kg MgSO 4 10 min in 100 ml of 0.9% normal saline through 10 min and direct IV 5 ml 0.9% normal saline.


All patients received 1 mg atropine sulfate IV and Afrin nasal decongestant drops in the right nostril. Topical anesthesia was achieved by nebulizer for 10 min using 10 ml lidocaine 2%.

After preparation of patients, nastroacheal tube (8 mm) was inserted through the right nostril into the oropharynx, and then well lubricated fiberoptic bronchoscope (STARZ 5-4 mm) was passed through the tube and manipulated to identify the epiglottis and cords. The bronchoscope was advanced into the trachea to the level of the carina, then the tube threaded over it.

The degree of difficulty of intubation was classified by an experienced observer according to the following. [1]

Not difficult

If no manipulation of the tip of the scope was needed.

Moderately difficult

Moderate manipulation of the bronchoscope in all directions was necessary to locate the cords.

Difficult

It would be difficult to identify the cords extensive manipulation of the bronchoscope in all directions with change in position of the operator.

Furthermore, the intubations time was measured, which is the time from insertion of the bronchoscope to completion of intubation. All the medications were prepared by an anesthesiologist who was not involved in any other aspect of the study. All syringes were identical and had similar volumes of the test and placebo solutions. The investigator who administered the drug, the anesthesiologist who performed the procedure and the patients, were unaware of the group allocated and the drug that was received by the patient.

Monitoring

Mean arterial pressure (MAP), heart rate and oxyhemoglobin saturation (PO 2 ) through pulse oximetry were monitored.

Hypoxemic episodes were defined as SPO 2 <90% and lasting ≥10 s. Apnea was defined as the absence of spontaneous respiration for >15 s. If hypoxemia or apnea occurred, spontaneous respiration was encouraged by vocal or tactile stimuli.

If hypotension occurred (MAP decreased ≥30% of baseline, 6 mg ephedrine was administrated. If heart rate decreased to <50 beat/min, 0.6 mg atropine sulfate IV was given.

In all patients to blow the secretions away from the tip of fiberoptic bronchoscopic (FOB), oxygen was insufflated through the suction port of the instrument (2 L/min).

The tip of FOB was immersed in warm saline (37°C) 1 min prior to insertion to prevent fogging.

Statistical analysis

The sample size was calculated to be N = 40 based on the following considerations: 95% confidence level, 80% power of the study. Equal size of the studied groups the estimated outcome to range between 50% and 80% between the studied groups. Statistical analysis was performed using one-way analysis of variance for normally distributed parametric data. Time required for nasotracheal intubation, procedure adverse events (case of FOB intubations, hypoxia, and apnea) were analyzed by the Kruskal-Wallis test followed by the post hoc multiple comparison tests using the Dunnett method. P < 0.05 was considered as statistically significant.


   Results Top


A total of 130 patients were randomized into the study, of which ten patients were excluded. Of these, six patients had inadequate anesthesia and were given general anesthesia. Four patients went into active vomiting leading to prolong the procedure time. Statistical analysis was performed in the remaining 120 patients, 40 in each group.

There was no statistically significant difference between the groups as regard to patient demography and hemodynamics before the procedure [Table 1] and [Table 3]. The time required for nasotracheal intubation was significantly less in the Groups MD and MS, as compared with the control Group S. (Group MD: 9.05 + 1.95 min, Group MS: 3.75 + 0.75 min and Group S: 16.85 + 1.7 min). This difference however, significant between Groups MD and MS [Table 2]. The number of fiberoptic intubation was significantly more in the MD and MS groups, as compared to the control group. Easy (control group: 0, Group MD: 25 and Group MS: 35), moderate difficulty (control group: 5, Group MD: 12 and Group MS: 4) and difficult (control group: 35, Group MD: 3 and Group MS: 1) [Table 3]. Procedure adverse events were significantly lower in Group MS as compared to Group S and Group MD. 20 patients in Group S and ten in Group MD had procedure hypoxia, six patients in Group S and two in Group MD had procedure apnea whereas, none of the patients in the MS group experienced this [Table 3]. After medication and just before intubation heart rate was significantly less in the group in Groups MD and MS, as compared to the control group (Group MD: 77 + 7.7beat/min, Group MS 70 + 5.6 beat/min and Group S 80 + 7.8 beat/min). This difference, however, significant between Group MD and Group MS. MAP was significantly less in the groups MD and MS, as compared to the control group. (Group MD: 90 + 8.5 mmHg, Group MS 80 + 8.1 mmHg and Group S 105 + 10.5 mmHg). This difference however, significant between Groups MD and MS.
Table 1: Demographic data

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Table 2: Intubation time (min)

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Table 3: Procedure adverse events

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   Discussion Top


Midazolam is a water soluble benzodiazepine with an elimination half-life of about 2 h and a rapid onset and a short duration of action in normal subjects. [17] Its primary metabolite is pharmacologically active. Elderly patients are extremely sensitive to midazolam and extreme caution is recommended with its in elderly. [3] Midazolam caused respiratory depression. With low doses the decreased tidal volume is compensated for by an increased respiratory rate, with larger doses, this compensation mechanism is lost, and hypoxemia or apnea may occur. [4],[5],[6]

A total of 1615 adverse events after use of Midazolam have been reported to the department of health and human services as a June 27, 1989. The dose of Midazolam report eddy administrated most often ranged from 1 to 10 mg. These reactions ranged from Hiccup to death. The most frequently reported adverse reaction was apnea, hypoxia or cyanosis. Fifty times reported from a total of 86 deaths occurred in the adverse drug reaction reported in US. [8]

This study shows that IV MgSO 4 45 mg/kg improved awaken FOB intubation without adverse hemodynamic or respiratory effects.

The mechanism of action of Mg appears to be multifactorial. It has analgesic, anesthetic and muscle relaxant effects. [14],[15],[16]

Magnesium is the 4 th most abundant cation in the body and the 2 nd most an abundant intracellular cation. [16],[17],[18] It acts as a natural Ca + = antagonist regulating Ca ++ access into the cell [19] it has the potential to treat and prevent pain by acting as an antagonist at N-methyl-D-aspartate receptors. [20]

The study of tramer et al. [20] showed the value of Mg as adjuvant in postoperative analgesia. Patients receiving Mg required less morphine had less discomfort and sleep better during 1 st 48 h than those receiving morphine alone. Three respiratory depressions occurred in the group receiving morphine only versus none in the group treated with morphine and Mg. Koini et al. [21] have reported similar results, with a reduced analgesic use both intra- and post-operatively.

Magnesium is considered to be a muscle relaxant like agent. Neuromuscular transmission isolated by reduction in the release of acetylcholine at motor nerve terminal. [15] A clinical study demonstrated that a rapid infusion of MgSO 4 (50 mg/kg) can re-establish relevant degree of muscle paralysis in patients who have just recovered from nondepolarizing blocking agents. [22],[23]

In patients with Tetanus MgSO infused at doses providing serum concentrations of 2-4 mmol/L allowed good control of spasm and muscle rigidity. [24]

Magnesium decreases the amount of acetylcholine released from motor nerve terminal, leading to diminished exact ability of the muscle fiber itself and reduction in the amplitude of the end plate potential. It therefore, potentiates the nondepolarizing neuromuscular blocking agents. [25],[26]

Magnesium decreases catecholamine release from the adrenal medulla and adrenergic nerve endings it obtunds the pressor response to laryngoscopy and intubation. [16]

Choi et al. [25] concluded that IV Mg SO4 reduced propofol infusion requirements. It could be related to the sedative effect of Mg. Mg has been reported to produce general anesthesia and to enhance the activity of local anesthetic agents. [27]

A narcotic state inhuman being undergoing surgical operations was achieved in a study by Peck and Meltzer who reported three patients. Undergoing hernioplasty under attempted anesthesia by MgSO 4 infusion. [18]


   Conclusion Top


Fiberoptic bronchoscopic tracheal intubation in MgSO 4 group was easier faster and without hemodynamic or respiratory adverse effects as compared with midazolam group.

Hence, we recommend IV MgSO 4 to facilitate awaken FOB tracheal intubations.

 
   References Top

1.
Johnson DM, From AM, Smith RB, From RP, Maktabi MA. Endoscopic study of mechanisms of failure of endotracheal tube advancement into the trachea during awake fiberoptic orotracheal intubation. Anesthesiology 2005;102:910-4.  Back to cited text no. 1
    
2.
Ovassapian A, Yelich SJ, Dykes MH, Brunner EE. Fiberoptic nasotracheal intubation - Incidence and causes of failure. Anesth Analg 1983;62:692-5.  Back to cited text no. 2
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3.
Kundra P, Kutralam S, Ravishankar M. Local anaesthesia for awake fibreoptic nasotracheal intubation. Acta Anaesthesiol Scand 2000;44:511-6.  Back to cited text no. 3
    
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Schwartz D, Johnson C, Roberts J. A maneuver to facilitate flexible fiberoptic intubation. Anesthesiology 1989;71:470-1.  Back to cited text no. 4
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5.
Xue FS, He N, Liao X, Xu XZ, Xu YC, Yang QY, et al. Clinical assessment of awake endotracheal intubation using the lightwand technique alone in patients with difficult airways. Chin Med J (Engl) 2009;122:408-15.  Back to cited text no. 5
    
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Rosenstock CV, Thøgersen B, Afshari A, Christensen AL, Eriksen C, Gätke MR. Awake fiberoptic or awake video laryngoscopic tracheal intubation in patients with anticipated difficult airway management: A randomized clinical trial. Anesthesiology 2012;116:1210-6.  Back to cited text no. 6
    
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Simmons ST, Schleich AR. Airway regional anesthesia for awake fiberoptic intubation. Reg Anesth Pain Med 2002;27:180-92.  Back to cited text no. 7
    
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9.
Lukomsky GI, Ovchinnikov AA, Bilal A. Complications of bronchoscopy: Comparison of rigid bronchoscopy under general anesthesia and flexible fiberoptic bronchoscopy under topical anesthesia. Chest 1981;79:316-21.  Back to cited text no. 9
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Simpson FG, Arnold AG, Purvis A, Belfield PW, Muers MF, Cooke NJ. Postal survey of bronchoscopic practice by physicians in the United Kingdom. Thorax 1986;41:311-7.  Back to cited text no. 10
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Pearce SJ. Fibreoptic bronchoscopy: Is sedation necessary? Br Med J 1980;281:779-80.  Back to cited text no. 11
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Rees PJ, Hay JG, Webb JR. Premedication for fibreoptic bronchoscopy. Thorax 1983;38:624-7.  Back to cited text no. 12
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Herroeder S, Schönherr ME, De Hert SG, Hollmann MW. Magnesium-Essentials for anesthesiologists. Anesthesiology 2011;114:971-93.  Back to cited text no. 13
    
14.
Dubé L, Granry JC. The therapeutic use of magnesium in anesthesiology, intensive care and emergency medicine: A review. Can J Anaesth 2003;50:732-46.  Back to cited text no. 14
    
15.
Fawcett WJ, Haxby EJ, Male DA. Magnesium: Physiology and pharmacology. Br J Anaesth 1999;83:302-20.  Back to cited text no. 15
    
16.
Mallampati SR, Gatt SP, Gugino LD, Desai SP, Waraksa B, Freiberger D, et al. A clinical sign to predict difficult tracheal intubation: A prospective study. Can Anaesth Soc J 1985;32:429-34.  Back to cited text no. 16
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17.
Roche Product Ltd. Midazolam (Hypnovel) Data Sheet. Wlwexn Gerden City: Roche; 1989.  Back to cited text no. 17
    
18.
Peck CH, Meltzer SJ. Anaesthsia in Humman beings by I.V. Injeciton of MgSO4. J Am Med Assoc 1916;601:1131-3.  Back to cited text no. 18
    
19.
Iseri LT, French JH. Magnesium: Nature′s physiologic calcium blocker. Am Heart J 1984;108:188-93.  Back to cited text no. 19
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20.
Tramer MR, Schneider J, Marti RA, Rifat K. Role of magnesium sulfate in postoperative analgesia. Anesthesiology 1996;84:340-7.  Back to cited text no. 20
    
21.
Koinig H, Wallner T, Marhofer P, Andel H, Hörauf K, Mayer N. Magnesium sulfate reduces intra-and postoperative analgesic requirements. Anesth Analg 1998;87:206-10.  Back to cited text no. 21
    
22.
Hans GA, Bosenge B, Bonhomme VL, Brichant JF, Venneman IM, Hans PC. Intravenous magnesium re-establishes neuromuscular block after spontaneous recovery from an intubating dose of rocuronium: A randomised controlled trial. Eur J Anaesthesiol 2012;29:95-9.  Back to cited text no. 22
    
23.
Attygalle D, Rodrigo N. Magnesium as first line therapy in the management of tetanus: A prospective study of 40 patients. Anaesthesia 2002;57:811-7.  Back to cited text no. 23
    
24.
Savarenese JJ, Cadwell JE, Lien CA. Phamraoclogy of muscle relaxants and their antognists. In: Miler RD, editor. Anesthesia. 5 th ed. Philadelphia: Churchill Living Stone; 2000. p. 463.  Back to cited text no. 24
    
25.
Choi JC, Yoon KB, Um DJ, Kim C, Kim JS, Lee SG. Intravenous magnesium sulfate administration reduces propofol infusion requirements during maintenance of propofol-N2O anesthesia: Part I: Comparing propofol requirements according to hemodynamic responses: Part II: Comparing bispectral index in control and magnesium groups. Anesthesiology 2002;97:1137-41.  Back to cited text no. 25
    
26.
Maltzer SJ, Auer J. Physiological and pharmaoclogical studies on magn salts. II. Narcotizing effects of magn salts upon nerve fibers. Am J Physiol 1906;16:233-8.  Back to cited text no. 26
    
27.
Coutinho EM. Calcium, magnesium, and local anesthesia. J Gen Physiol 1966;49:845-6.  Back to cited text no. 27
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    Tables

  [Table 1], [Table 2], [Table 3]



 

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