Anesthesiology 2001; 94:259–62 © 2001 American Society of Anesthesiologists, Inc. Lippincott Williams & Wilkins, Inc. Effect of Cricoid Pressure on the Success of Endotracheal Intubation with a Lightwand R. Eric Hodgson, M.B., Ch.B.(Hons.), F.C.A.(S.A.)(Crit. Care),* P. Dean Gopalan, M.B., Ch.B., F.C.A.(S.A.),* Richard C. Burrows, M.B., Ch.B., F.C.A.(S.A.)(Crit. Care),† Khangelani Zuma, M.Sc.‡ Background: The lightwand may be useful as an alternative Material and Methods for tracheal intubation during a rapid-sequence induction of anesthesia in the presence of a full stomach. This study was The study was approved by the Ethics Committee of undertaken to assess the effect of application of cricoid pres- sure on the success of lightwand intubation. the Medical Faculty of the University of Natal. Sixty adult Methods: Sixty adult female patients presenting for abdomi- patients presenting to Addington hospital for total ab- nal hysterectomy were randomly allocated to lightwand intu- dominal hysterectomy gave informed consent to partic-Downloaded from http://pubs.asahq.org/anesthesiology/article-pdf/94/2/259/402068/0000542-200102000-00015.pdf by guest on 24 September 2021 bation with and without cricoid pressure. The time to successful ipate in the study. Patients who had previously proved intubation and number of attempts were recorded. difficult to intubate or in whom a difficult intubation was Results: All 30 patients allocated to intubation without cricoid suspected were excluded from the study. Patients with pressure were intubated successfully at the first attempt within significant cardiorespiratory disease were also excluded. a median time of 28 s (95% confidence interval, 18–77 s). 4 Lightwand intubation with cricoid pressure was successful in 26 Airway evaluation included a Mallampati score and mea- of 30 patients at the first attempt, but the median time to surement of interincisor gap, thyromental, and sterno- successful intubation was significantly longer at 48.5 s (95% mental distances. -Three patients re- On arrival in the operating room, patients were ran .(0.001 ؍ confidence interval, 36–78 s; P quired two attempts for successful intubation, and one could domized to lightwand intubation with CP (CP group) or not be intubated with the lightwand while cricoid pressure was without CP (no CP group). The study was designed to being applied. Conclusions: The lightwand cannot be recommended for the allow a difference of 5-s intubation time between these first attempt at intubation where cricoid pressure is being ap- two groups to be detected at 5% level of significance plied because the time to successful intubation is significantly with power of 70%. Randomization was performed using prolonged, and the failure rate for the first attempt at lightwand sequentially numbered envelopes that contained data intubation is 13%. sheets that had been randomly allocated by an intensive care unit nurse who did not take any further part in the A RECENT review highlighted the role of the lightwand trial. in airway management.1 The lightwand has been used Intravenous access was established, and monitors, in- successfully for endotracheal intubation and may be es- cluding electrocardiogram, noninvasive blood pressure, pecially useful if laryngeal visualization is difficult and and pulse oximetry, were placed. Baseline heart rate, there is no evidence of an obstructive lesion of the blood pressure, and oxygen saturation were recorded. mouth, pharynx, or larynx.2 Patients with full stomachs Patients then breathed 100% oxygen for 3 min from a who require anesthesia may regurgitate during rapid- circle system, with the absorber out of the circuit and a sequence induction. Regurgitation and aspiration are fresh gas flow of 6 l/min. Exhaled carbon dioxide was prevented by application of external pressure to the measured using a sidestream capnograph. Anesthesia cricoid cartilage (cricoid pressure [CP] or the Sellick was induced with thiopentone 5 mg/kg and, after con- maneuver3) to occlude the esophagus. There has been firmation of easy mask ventilation, muscle relaxation was no previous study of the effect of CP on the success of provided by vecuronium 0.1 mg/kg. Isoflurane 2% was lightwand intubation. This study was undertaken in nor- added to the inspired oxygen, and mask ventilation con- mal patients undergoing elective surgery to assess the tinued until confirmation of complete paralysis by ab- potential usefulness of the lightwand for intubation of sence of response to train-of-four stimulation of the ulnar patients in whom CP is being applied. nerve at the wrist. Patients who required CP had this applied by the anesthetic nurse allocated to the operating room before the start of the intubation attempt. All nurses were ex- * Consultant Anesthesiologist, † Chief Consultant Anesthesiologist, Depart- ment of Anaesthesiology, University of Natal and Addington Hospital. ‡ Statis- perienced at providing CP, and the application of CP was tician, South African Medical Research Council, Institute of Biostatistics. confirmed by the anesthesiologist performing the intu- Received from the Department of Anaesthesiology, University of Natal and bation (E. H.). Different nurses were used as it was Addington Hospital, Congella, South Africa, and the South African Medical Re- search Council, Institute of Biostatistics, Durban, Kwazulu-Natal, South Africa. impossible to allocate a single nurse to this task because Submitted for publication June 5, 2000. Accepted for publication September 25, of staffing limitations. The use of different nurses is 2000. Support was provided solely from institutional and/or departmental sources. consistent with clinical conditions where the nature of 5 Address reprint requests to Dr. Hodgson: Department of Anaesthesiology, CP may vary depending on the person applying it. Faculty of Medicine, University of Natal, Private Bag 7, Congella, 4013 South Africa. Address electronic mail to: [email protected]. Individual article reprints Intubation was performed using a well-lubricated may be purchased through the Journal Web site, www.anesthesiology.org. size-7 endotracheal tube placed over a lightwand (Surch- Anesthesiology, V 94, No 2, Feb 2001 259 260 HODGSON ET AL. Lite; Aaron Medical, St Petersburg, FL). For the intuba- Table 1. Age, Weight, and Airway Characteristics tion, the distal end of the wand and covering tube were CP No CP bent at a 90° angle (“hockey stick”), and patients were Parameter (n ϭ 30) (n ϭ 30) placed in the optimum “sniff” position (neck flexed and Weight (kg) 71.4 (13.6) 70.9 (14.8) head extended). The jaw was then lifted forward with Age (yr) 43.9 (12.4) 40.2 (9.6) the left hand of the intubating anesthesiologist (E. H.), Sternomental distance (cm) 12.9 (1.6) 13.1 (1.7) and the lightwand and tube were passed down the Thyromental distance (cm) 6.8 (0.83) 7.3 (1.6) Interincisor gap (cm) 2.7 (0.69) 3.0 (0.87) midline of the tongue using the right hand. The ambient Mallampati score (median Ϯ range) 2 (1–3) 2 (1–3) lights were dimmed to assist visualization of the transil- lumination pattern. If the transillumination pattern could Values are mean (ϮSD), except the Mallampati score, which is median not be visualized, the wand and tube were removed, the (range). No significant differences between the groups could be shown. “hockey stick” configuration restored, the “sniff” posi- Downloaded from http://pubs.asahq.org/anesthesiology/article-pdf/94/2/259/402068/0000542-200102000-00015.pdf by guest on 24 September 2021 Patients were examined 24 h postoperatively and tion reassessed and optimized, and the attempt was asked about the presence of sore throat, which was repeated with the wand directed more posteriorly to graded by means of a 10-cm visual analog score. enter the proximal esophagus. The wand was then slowly withdrawn until the transillumination pattern Statistical Analysis appeared. Data was analyzed using SAS version 6.12 (SAS Insti- Each intubation attempt was timed from removal of tute, Cary, NC) and S-plus 4.5 (Mathsoft Inc., Cambridge, the face mask until detection of carbon dioxide by the MA). The t test was used to compare continuous vari- capnograph or until replacement of the face mask. The ables, and the chi-square test was used for categoric need to replace the face mask, which was performed variables. The log-rank test was used for the comparison after 3 min or if desaturation to 95% occurred, was of the Kaplan-Meier curves obtained from the total time considered to be a failed intubation attempt. A total of to successful intubation for each patient. All P values three attempts was allowed with face mask ventilation were derived from two-sided tests. A P value less than or with 100% oxygen and 2% isoflurane to a saturation of equal to 0.05 was considered to indicate statistical greater than 98% between attempts. significance. All intubations were performed by a single investigator (E. H.) with 6 months of experience in the use of the lightwand, including a number of difficult intubations. Results However, the investigator did not have previous experi- The groups were similar in terms of age, weight, Mal- ence with lightwand intubation in the presence of CP. lampati score, interincisor gap, and sternomental and This was also consistent with clinical conditions where thyromental distances (table 1). All patients could be practicing intubation with CP in patients in whom the intubated at the first attempt without desaturation in the maneuver is not clinically indicated would be unusual. no CP group (table 2). Three failed attempts at lightwand intubation was con- In the CP group, three patients required two attempts sidered a failure of the technique and was an indication for successful intubation, and intubation could not be for conventional laryngoscopic intubation using an ap- performed with the lightwand in one patient (table 2).