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*Department of Anesthesia and Intensive Care, and
Ludwig Boltzmann Institute for Economics of Medicine in Anesthesia and Intensive Care, Vienna City Hospital-Lainz, Vienna, Austria
Address correspondence and reprint requests to Dr. W. Oczenski, Department of Anesthesia and Intensive Care, Vienna City Hospital Lainz, Wolkersbergenstr. 1, A-1130 Vienna, Austria. Address e-mail to ocw{at}ana.khl.magwien.gv.at
| Abstract |
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Implications: In this study, we showed that the hemodynamic and catecholamine stress responses after insertion of the Combitube® (Kendall-Sheridan Catheter Corp., Argyle, NY) were significantly higher compared with laryngeal mask airway or endotracheal intubation. We conclude that the increased stress response to insertion of a Combitube® may represent a serious hazard to patients with cardiovascular disease.
| Introduction |
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For emergencies and cardiopulmonary resuscitation, the esophageal-tracheal Combitube® (CT; Kendall-Sheridan Catheter Corp., Argyle, NY) has been introduced as an effective technique, providing adequate oxygenation and ventilation with a low risk/benefit ratio (14). Despite its widespread use, little is known about hemodynamic and catecholamine stress responses after insertion of the CT.
Thus, in a prospective, randomized trial, we investigated and compared the hemodynamic and catecholamine stress responses after insertion of the CT with that after endotracheal intubation (ET) and insertion of a laryngeal mask airway (LMA). We hypothesized that insertion of the CT elicits higher serum levels of epinephrine and norepinephrine and a more pronounced hemodynamic reaction than the two other methods.
| Methods |
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The laryngo-pharyngeal region was examined preoperatively and graded according to Samsoon and Young's (5) modification of the Mallampati test.
Seventy-five patients (2065 yr, ASA physical status IIII) undergoing elective urological and gynecological surgical procedures (duration 12 h) were randomly allocated to one of three groups: ET group, LMA group, and CT group. They were randomly assigned to one of four participating anesthetists thoroughly experienced in handling all three devices.
After premedication with diazepam 10 mg per os, anesthesia was induced with fentanyl 3 µg/kg and propofol 23 mg/kg IV until loss of eyelash reflex, and anesthesia was maintained with a 50- to 100-µg · kg-1 · min-1 propofol infusion, 60% nitrous oxide in oxygen, and supplements of fentanyl 50100 µg if clinically required. Hemodynamic variables were monitored invasively via a radial artery cannula.
Rocuronium 600 µg/kg was administered for ET and/or mechanical ventilation via the LMA or the CT. Intubation/airway insertion was attempted 120 s after the beginning of injection of rocuronium. Duration of intubation/airway insertion was defined as the time from the start of intubation/airway insertion until inflation of the cuffs.
Difficulty of intubation was graded IIV according to the criteria of Cormack and Lehane (6). Intubation of the trachea was attempted with endotracheal tubes, size 7.5 for women and 8.5 for men.
Women were ventilated via a LMA size 3, men via a LMA size 4. The LMA was inserted blindly according the recommended instructions (7). The cuff was inflated with 25 mL of air for size 3 and 35 mL of air for size 4 devices. All patients in the CT group were ventilated via a CT size SA 37F according to the recommended guidelines (8). The oropharyngeal balloon was inflated with 85 mL of air, and the distal balloon was inflated with 12 mL of air.
Insertion conditions of the LMA or CT were graded according to ease of insertion: excellent (no resistance to insertion), good (slight resistance to insertion), poor (moderate resistance to insertion), or impossible. If insertion was not possible, the patients were intubated endotracheally.
Systolic arterial pressure (SAP), diastolic arterial pressure (DAP), mean arterial pressure (MAP), and heart rate (HR) were recorded immediately before and 1, 2, 3, 5, 7, 10, and 15 min after intubation/airway insertion; and immediately before and 1, 3, and 5 min after extubation/airway removal.
SaO2, end-tidal CO2, PaO2, PaCO2, pH, and peak airway pressures were recorded. Arterial blood samples for determination of catecholamine levels were drawn after the induction of anesthesia, immediately before and 1, 5, and 10 min after intubation/airway insertion (before skin incision); and 1 min after extubation/airway removal. The blood samples were collected in precooled (28°C) tubes containing EDTA and reduced glutathione. The samples were immediately centrifuged at 0°C. All samples were analyzed in duplicate using liquid chromatography and electrochemical detection (Beckman, Palo Alto, CA). Interassay variation was 5.4% for epinephrine and 6.4% for norepinephrine.
The Kruskal-Wallis test was used for intergroup comparisons. Multiple Mann-Whitney U-tests were used for nonparametric data comparisons, in which the
risk was controlled by the result of the global test. The intraindividual tests for changes versus baseline were based on Wilcoxon's signed rank test within the study groups. Baseline data for every measurement variable were defined as the data immediately before intubation/airway insertion. Data were expressed as means ± SDs. P values <0.05 were considered statistically significant.
| Results |
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In the CT and ET groups (Figs. 1 and 2), significant increases in HR, SAP, DAP, and MAP (P < 0.01) were detected from 1 to 10 min compared with baseline values. After LMA insertion, no significant increase in HR occurred, whereas SAP, DAP, and MAP slightly increased at 1 min (P < 0.05).
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All three groups showed a significant increase in HR (P < 0.05), SAP, DAP, and MAP (P < 0.01) 1, 3, and 5 min after extubation/airway removal. No significant differences were detected among the groups.
Plasma catecholamine levels are shown in Table 2 and 3.
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| Discussion |
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Based on the literature, we anticipated that the insertion of a LMA would elicit a much smaller hemodynamic and catecholamine response than tracheal intubation (9,10). However, it was not clear that using a CT was more stressful than ET as direct laryngoscopy is avoided. Moreover, blind insertion of a CT most often results in an esophageal position, thus resembling the insertion of a LMA.
Differentiating the effects of laryngoscopy and ET, Shribman et al. (11) concluded that the major cause of the sympathoadrenal response to tracheal intubation arises from stimulation of the supraglottic region by tissue irritation induced by direct laryngoscopy. Insertion of the tube through the vocal cords and inflation of the cuff in the infraglottic region should contribute very little additional stimulation. Hassan et al. (12) reported that, by activating proprioceptors, direct laryngoscopy induces arterial hypertension, tachycardia, and increased catecholamine concentrations proportional to the intensity of the stimulus exerted against the base of the tongue. However, subsequent tracheal intubation should stimulate additional receptors in the larynx and the trachea, thus enhancing the hemodynamic and epinephrine response (13). In our study placement of the CT was always esophageal. Thus, we attribute our findings to a higher mechanical pressure on the tissues of the anterior pharyngeal region, possibly by the 85-mL cuff of the CT and the irritation of the esophagus by the insertion of the device and subsequent inflation of the smaller blocking balloon.
The unequal hemodynamic and catecholamine stress reaction between CT and ET was not a result of a difference in the time necessary for insertion of the CT versus ET. This is important to note, as Stoelting et al. (14) demonstrated that the time required for performing ET directly correlates with an increase in MAP.
Hemodynamic and catecholamine responses to insertion of the LMA were minimal, which supports the findings of Wilson et al. (10), who reported that the cardiovascular responses induced by laryngoscopy and intubation were more than twice as high as those produced by the insertion of a LMA. Our data contradict the results of Braude et al. (15) and Griffin et al. (16), who found no significant difference in pressure response after insertion of a LMA and ET.
After extubation/airway removal, the hemodynamic and plasma catecholamine concentrations reached their highest levels in all three groups. Compared with the LMA, norepinephrine concentrations were significantly higher after removal of the CT, whereas those in ET patients were not statistically different from those in either group. Our results are in accordance with the findings of Fujii et al. (17), who showed that removal of the LMA is associated with fewer cardiovascular changes than tracheal extubation in normotensive and hypertensive patients. In contrast to our data, Lowrie et al. (18) demonstrated an absence of norepinephrine response after endotracheal extubation, from which they concluded that the extubation had less effect than tracheal intubation and laryngoscopy. However, the stress reaction seen in our plasma catecholamine levels correlates well to the clinically evident arousal seen in the patients during the extubation/airway removal procedure.
Frass et al. (19) reported a significantly higher mean PaO2 during ventilation via a CT compared with an ET. This was attributed to a prolonged expiratory flow time and the occurrence of a small positive end-expiratory pressure as a result of an increase in expiratory resistance caused by the double-lumen design of the CT and integration of the vocal cords into the airway.
The increase in expiratory resistance is a function of the reduced total cross-sectional area of the CT holes, which may, on occasion, be further reduced by the collapse of surrounding pharyngeal tissue during expiration. An increase in laryngeal tone may also contribute to flow resistance; in extreme cases, overzealous inflation of the esophageal balloon may even compress the posterior tracheal wall. However, in our study there was no significant difference in PaO2 and PaCO2 among the study groups.
We found significantly higher inspiratory peak pressures in the CT group than in the other two groups. Inspiratory peak pressure is an artifact of its site of measurement at the airway opening attributable to the resistance of the double-lumen airway already reported by Frass et al. (19). Intratracheal pressures with a CT or ET were in the same range, with similar degrees of lung inflation, when measured by a catheter placed below the vocal cords (19).
The increased hypertensive response to insertion of the CT may represent a serious hazard to patients with cardiovascular or cerebrovascular disease, e.g., aortic dissection or subarachnoidal bleeding. Because stress during the induction of anesthesia is a major factor in myocardial ischemia, caution should be applied when using the CT in patients with cardiac risk, as the release of endogenous catecholamines increases myocardial oxygen demand. If insertion of the CT is considered, effective measures should be implemented to minimize the stress responses. The main indication for the CT is the unexpected difficult airway, failed tracheal intubation, and perhaps the inability to visualize the vocal cords in a patient at risk of aspiration of gastric contents, e.g., upper airway bleeding or continued vomiting.
| References |
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