Recurrent Laryngeal Nerve Palsy after Anterior Cervical Spine Surgery: The Impact of Endotracheal Tube Cuff Deflation, Reinflation, and Pressure Adjustment

Background: Vocal fold immobility (paresis or paralysis) from recurrent laryngeal nerve injury remains an important cause of morbidity after anterior cervical spine surgery. A maneuver involving endotracheal tube (ETT) cuff manipulation has been proposed to reduce its incidence. This study is a randomized, prospective, double-blind investigation to test the hypothesis that ETT cuff manipulation reduces the incidence of postoperative vocal fold immobility after anterior cervical spine surgery.

Methods: One hundred patients scheduled to undergo anterior cervical spine surgery were randomly assigned to one of two groups. After inducing general endotracheal anesthesia, patients in the intervention group had their ETT cuff pressures maintained at 20 mmHg or less. After placement of self-retaining retractors, the ETT cuff was deflated for 5 s and then reinflated. Patients in the control group had no further manipulation of their ETT once the cuff was inflated after intubation. Cuff pressures in both groups were recorded before skin incision (baseline) and after placement of self-retaining retractors (peak). Patients' vocal fold motion was evaluated by indirect laryngoscopy performed preoperatively and postoperatively. The examination was videotaped and reviewed by a blinded otolaryngologist. Postoperative vocal fold motion was graded as normal, paretic, or paralyzed.

Results: Complete data were available in 94 patients. The incidence of vocal fold paralysis was 3.2% (95% confidence interval, 0.7-9.4%). Cuff manipulation decreased ETT cuff pressure but did not reduce the incidence of vocal fold immobility (15.4% vs. 14.5%).     

On the incidence, cause, and prevention of recurrent laryngeal nerve palsies during anterior cervical spine surgery

STUDY DESIGN: A retrospective review of contemporaneously acquired clinical data supplemented by experimental cadaver dissection. OBJECTIVE: To establish the incidence and mechanism of vocal cord paralysis after anterior cervical spine surgery and to determine whether controlling for endotracheal tube (ET)-laryngeal wall interactions induced by the cervical retraction system could decrease the rate of paralysis. SUMMARY OF BACKGROUND DATA: Vocal cord paralysis is the most common otolaryngologic complication after anterior cervical spine surgery. However, the quoted frequency of this varies considerably, and the cause of the injury is not clearly defined. As a result, various, and at times contradictory, recommendations to prevent this are presented without data to support their effectiveness. METHODS: Data gathered at the time of surgery and during follow-up visits on 900 consecutive patients who underwent anterior cervical spine surgery with plating during a 12-year interval were entered into a computerized database and reviewed for complications and procedural risk factors. After the first 250 cases an intervention consisting of monitoring ET cuff pressure and release of pressure after retractor replacement or repositioning was used, which allowed the ET to recenter within the larynx. The ET-laryngeal wall relation also was studied in fresh intubated cadavers using videofluoroscopic images, before and after retractor placement. RESULTS: Thirty incidences of vocal cord paralysis consistent with recurrent laryngeal nerve (RLN) injury were identified: 27 temporary and 3 permanent. The rate of temporary paralysis decreased from 6.4% to 1.69% (P = 0.0002) after institution of the described maneuver. The findings confirmed that the retractor displaced the larynx against the shaft of the ET, allowing impingement on the vulnerable intralaryngeal segment of the RLN. CONCLUSIONS: The most common cause of vocal cord paralysis after anterior cervical spine surgery is compression of the RLN within the endolarynx. Monitoring of ET cuff pressure and release after retractor placement may prevent injury to the RLN during anterior cervical spine surgery.     

Vocal cord palsy after anterior cervical spine surgery: a qualitative systematic review

Background contextVocal cord palsy (VCP) is a known complication of anterior cervical spine surgery. However, the true incidence and interventions to minimize this complication are not well studied.PurposeTo conduct a systematic review to identify the incidence, risk, and interventions for VCP after anterior cervical spine surgery.Study designThis is a qualitative systematic literature review.SampleProspective and retrospective trials of patients undergoing anterior cervical spine surgery that reported on postoperative VCP or recurrent laryngeal nerve palsy.Outcome measuresPrimary: incidence of VCP after anterior cervical spine surgery; secondary: risk factors and interventions for prevention of VCP after anterior cervical spine surgery.MethodsElectronic searches were conducted on Ovid Medline, EMBASE, Cochrane Central Register of Controlled Trials, and Cochrane Database of Systemic Reviews for clinical studies reporting VCP in anterior cervical spine surgery, limited to studies published between 1995 and June 2013 in English and French languages. After selection of studies independently by two review authors, data on incidence, risk, and interventions were extracted. Qualitative analysis was performed on three domains: quality of studies, strength of evidence, and impact of interventions.ResultsOur search has identified 187 abstracts, and 34 studies met our inclusion criteria. The incidence of VCP ranges from 2.3% to 24.2%. Significant heterogeneity in study design and definition of VCP were used in the published studies. There is good evidence that reoperation increases the risk of VCP. One study of moderate strength suggests that operating from the right side may increase the risk of VCP. Among the interventions studied, endotracheal tube (ETT) cuff pressure monitoring with deflation during retraction has shown to reduce the incidence from 6% to 2%, but this result was not confirmed by randomized control trials. Limited evidence exists for other interventions of intraoperative electromyographic monitoring and methylprednisolone.ConclusionsVocal cord palsy is a significant morbidity after anterior cervical surgery with incidence up to 24.2% in the immediate postoperative period, with a higher risk in reoperation of the anterior cervical spine. Moderate evidence exists for ETT cuff pressure adjustment in preventing this complication.     

Laryngeal Resistance before and after Minor Surgery: Endotracheal Tube versus Laryngeal Mask Airway™

Background: The placement of an endotracheal tube (ETT) may promote laryngeal swelling, which is an important cause of upper airway obstruction after extubation. The authors hypothesized that laryngeal swelling after ETT placement increases laryngeal resistance and tested that hypothesis by comparing postoperative laryngeal patency between patients with ETT placement and those with a Laryngeal Mask Airway(TM) (LMA(TM)).

Methods: Fourteen adult patients who underwent elective minor surgeries were randomly allocated to two groups whose airway would be managed through ETTs (the ETT group) or LMAs(TM) (the LMA(TM) group) during the surgery. While maintaining at sevoflurane 1 minimum alveolar concentration, the authors measured laryngeal resistance before and after surgery, during both spontaneous breathing and mechanical ventilation under complete paralysis. In addition, they endoscopically measured the vocal cord angle under complete paralysis.

Results: In association with marked swelling of the vocal cords, the vocal cord angle significantly decreased after surgery in the ETT group, whereas the angle did not change in the LMA group. Laryngeal resistance during mechanical ventilation significantly increased only in the ETT group. Laryngeal resistance during spontaneous breathing significantly increased after surgeries in both groups.     

Unilateral vocal cord paralysis following endotracheal intubation--a case report

A 41-year-old man of ASA physical status class I was scheduled to receive the video-assisted thoracoscopic T2 sympathectomy for hyperhidrosis palmaris. The elective surgery was performed smoothly under general anesthesia with endotracheal intubation. However, the patient complained of hoarseness in the postoperative period. A stroboscopic examination showed that the left vocal cord remained stationary in the paramedian position, signifying left vocal cord paralysis. In the case, we believed it was most likely that endotracheal intubation might be responsible for the unilateral vocal cord paralysis. The possible cause was that during placement or thereafter during positioning, the endotracheal tube was malposed or slipped upward, rendering its inflated cuff to rest against the vocal cords. Another reason was that the cuff which was over inflated made the vocal cords under constant pressure. Both conditions may cause damage to the anterior branch of the recurrent laryngeal nerve. We also discussed the general management and prophylaxis for the unilateral vocal cord paralysis.     

Laryngeal resistance before and after minor surgery: endotracheal tube versus Laryngeal Mask Airway

BACKGROUND: The placement of an endotracheal tube (ETT) may promote laryngeal swelling, which is an important cause of upper airway obstruction after extubation. The authors hypothesized that laryngeal swelling after ETT placement increases laryngeal resistance and tested that hypothesis by comparing postoperative laryngeal patency between patients with ETT placement and those with a Laryngeal Mask Airway trade mark (LMA). METHODS: Fourteen adult patients who underwent elective minor surgeries were randomly allocated to two groups whose airway would be managed through ETTs (the ETT group) or LMAs (the LMA group) during the surgery. While maintaining at sevoflurane 1 minimum alveolar concentration, the authors measured laryngeal resistance before and after surgery, during both spontaneous breathing and mechanical ventilation under complete paralysis. In addition, they endoscopically measured the vocal cord angle under complete paralysis. RESULTS: In association with marked swelling of the vocal cords, the vocal cord angle significantly decreased after surgery in the ETT group, whereas the angle did not change in the LMA group. Laryngeal resistance during mechanical ventilation significantly increased only in the ETT group. Laryngeal resistance during spontaneous breathing significantly increased after surgeries in both groups. CONCLUSIONS: Postoperative laryngeal resistance increases at least in part because of laryngeal swelling in patients with ETT placement, whereas alteration of laryngeal neural control mechanisms has been also indicated. The use of the LMA trade mark has an advantage over ETT placement in order to avoid postoperative laryngeal swelling.     

Optimization of endotracheal tube cuff filling by continuous upper airway carbon dioxide monitoring

Inappropriate cuff filling is responsible for various complications related to the use of an endotracheal tube (ETT). In this study, we evaluated an objective, noninvasive method for continuous assessment of leak around the ETT cuff by monitoring carbon dioxide pressure (P(CO2) in the upper airway. P(CO2) levels were measured by capnography simultaneously between the ETT cuff and the vocal cords, at the oropharynx, and in the nares of the nose. Cuff filling was regulated by an electronic controller to achieve the minimal pressure needed to prevent CO2 leak. Feasibility of the method was assessed in a human simulator and in a porcine model. Clinical function was evaluated in 60 patients undergoing surgery, comparing the method to the standard anesthesiologist evaluation. Linear correlations were observed between the ETT cuff pressure and P(CO2) level in the human simulator (R2 = 0.954, P < 0.0001) and in the porcine model (R2 > 0.98, P < 0.0001). Iodine leak around the ETT cuff, in the porcine model, occurred only when P(CO2) levels were >2 mm Hg. In the surgery patients, the mean ETT cuff pressure determined clinically by the anesthesiologist was significantly higher than the optimal cuff pressure assessed by P(CO2) (25.2 +/- 3.6 versus 18.2 +/- 7.8 mm Hg, respectively; P < 0.001). According to these findings, optimal ETT cuff filling pressure can be identified by monitoring P(CO2) at the nares or the oropharynx. IMPLICATIONS: A new, objective, noninvasive method for optimizing endotracheal tube cuff filling based on monitoring carbon dioxide levels in the upper airways can be used to identify the minimal cuff pressure necessary to eliminate leak and prevent aspiration.     

Laryngeal reflex before and after placement of airway interventions: endotracheal tube and laryngeal mask airway

BACKGROUND: Previous reports indicate that detrimental laryngeal function persists over several hours after tracheal extubation even in patients who have regained full consciousness from anesthesia. The authors hypothesize that even after minor surgery, the presence of an endotracheal tube (ETT) impairs the receptors at the vocal cord and diminishes the defensive laryngeal function. The hypothesis was tested by comparing types of experimentally induced laryngeal airway reflexes before and after surgery in anesthetized patients with use of either an ETT or a Laryngeal Mask Airway. METHODS: Twenty adult patients undergoing elective minor surgeries were randomly allocated into two groups, the ETT and Laryngeal Mask Airway groups, depending on the airway management method used during surgery. While maintaining sevoflurane at 1 minimum alveolar concentration, laryngeal and respiratory responses were elicited by instillation of distilled water on the vocal cords immediately before and after surgery. Furthermore, the vocal cord angles were endoscopically measured under complete paralysis. RESULTS: Some laryngeal reflex responses of both groups, particularly the cough reflex, were significantly attenuated after minor surgery. Significant narrowing of the glottic aperture was evident in patients with ETT placement but not in patients with Laryngeal Mask Airway placement. CONCLUSIONS: With either airway intervention, laryngeal defensive reflexes are depressed immediately after surgery even without visible laryngeal swelling. The sensory impairment attributable to the presence of an ETT cannot be the solo factor responsible for the modification of the defensive airway reflexes elicited from the larynx.     

Vocal cord paralysis after open-heart surgery.

Vocal cord paralysis is a known entity often described as a complication of neck surgery. A less frequent site of injury to the recurrent laryngeal nerve is the chest. The left side is usually more affected than the right side in view of its long intrathoracic segment. Only few cases of right vocal cord paralysis following open-heart surgery are reported in the literature. The purpose of this article is to review the common possible mechanisms of injury to the right recurrent laryngeal nerve following open-heart surgery in order to draw the attention of the caring physician to the clinical significance of such a complication. In fact, transient hoarseness following open-heart surgery may be an ominous sign of recurrent laryngeal nerve injury. It should not be assumed to be secondary to intralaryngeal edema. Several mechanisms of injury to the recurrent laryngeal nerve have been suggested: (1) through central venous catheterization; (2) by traction on the esophagus; (3) by direct vocal cord damage or palsy from a traumatic endotracheal intubation; (4) trauma by compression of the recurrent laryngeal nerve or its anterior branch at the tracheoesophageal groove by an inappropriately sized endotracheal tube cuff; (5) by a faulty insertion of a nasogastric tube; (6) median sternotomy and/or sternal traction pulling laterally on both subclavian arteries; (7) direct manipulation and retraction of the heart during open-heart procedures; (8) hypothermic injury with ice/slush. If vocal cord paralysis was overlooked as a possible complication of open-heart surgery, the patient may suffer from dysphonia in addition to problems of paramount importance such as inefficient cough and aspiration. Although it is true that the incidence of vocal cord paralysis remains very low, yet its presence is alarming and necessitates close follow up on the patient for the possible need of surgical intervention if recovery fails.     

改良单腔气管导管引导法对Univent管放置成功率的影响

目的评价改良单腔气管导管(ETT)引导法对Univent管左主支气管放置成功率的影响。方法需左侧肺萎陷的择期胸科手术患者80例,随机均分为改良组和常规组。气管插管前,将前端呈135°弯曲的Univent管放置于ETT(ID8.5mm)内,Univent管前端弯曲方向与ETT弯曲方向一致。改良组与常规组的主要不同点在于:内含Univent管的ETT过声门后即向左旋转90°(Univent管随ETT也向左旋转90°),两者向下推进至隆突,使ETT前端开口正对左主支气管口,然后将Univent管继续插入约5cm,ETT退至22～24cm处,用纤维支气管镜(FOB)检查Univent管是否进入左主支气管,并将Univent管调至最佳位置。记录Univent管试插次数,放置到最佳位置所需时间(从暴露声门开始),以及气道黏膜有无损伤。结果改良组Univent管一次试插成功率明显高于常规组(100%vs.60%,P<0.01);放置时间改良组明显短于常规组[(4.0±1.5)minvs.(10.0±5.5)min,P<0.01];气道黏膜损伤发生率改良组明显低于常规组(6.5%vs.17.5%,P<0.05)。结论改良ETT引导法使Univent管更容易被放置到左主支气管。     

Methods of endotracheal tube placement in patients undergoing pelviscopic surgery

Accidental endobronchial intubation is reported frequently during laparoscopic gynaecological surgery. We performed a prospective randomised study to compare three different methods of endotracheal tube placement in terms of susceptibility of accidental endobronchial intubation in patients undergoing laparoscopic gynaecologic surgery. The endotracheal tube was positioned by one of three methods: it was secured by palpating at the suprasternal notch while holding the pilot balloon (Group(Cuff)); by placing the 21 cm mark at the upper incisors (Group(21cm)); or by placing a guide mark, which was made on the surface of the tube 2 cm above the proximal end of the cuff at the level of the vocal cords (Group(VC)). The distance from the tip of endotracheal tube to the carina was measured with the patient in a neutral position (D(TC0)) and after the formation of pneumoperitoneum in the Trendelenburg position (D(TC1)). Eighty-eight patients were enrolled. Pneumoperitoneum and Trendelenburg position caused inward movement of the endotracheal tube toward the carina in 99%. In each group, the mean value of D(TC1) was significantly shorter than D(TC0) (Group(Cuff) 3.0 +/- 1.1 vs. 1.7 +/- 1.0, Group(21cm) 2.5 +/- 0.8 vs. 1.1 +/- 0.9, Group(VC) 3.5 +/- 0.7 vs. 2.3 +/- 0.8, D(TC0) vs. D(TC1) respectively) (all P < 0.01). Accidental endobronchial intubation occurred in 14%, with the lowest frequency in Group(VC) (2.6 %, P < 0.01) and the highest in Group(21cm), although this was not significantly (P = 0.09) different from Group(Cuff) (26.7% vs. 10.0%). The incidence of endobronchial intubation was lowest in Group(VC) but endobrochial intubation could not be avoided using any of these methods.     

Dysphagia after anterior cervical spine surgery: a systematic review of potential preventative measures

Background contextAnterior cervical spine surgery is one of the most common spinal procedures performed around the world, but dysphagia is a frequent postoperative complication. Many factors have been associated with an increased risk of swallowing difficulties, including multilevel surgery, revision surgery, and female gender.PurposeThe objective of this study was to review and define potential preventative measures that can decrease the incidence of dysphagia after anterior cervical spine surgery.Study designThis was a systematic literature review.MethodsA systematic review in the Medline database was performed. Articles related to dysphagia after anterior cervical spine surgery and potential preventative measures were included.ResultsTwenty articles met all inclusion and exclusion criteria. These articles reported several potential preventative measures to avoid postoperative dysphagia. Preoperative measures include performing tracheal exercises before the surgical procedure. Intraoperative measures can be summarized as avoiding a prolonged operative time and the use of recombinant human bone morphogenetic protein in routine anterior cervical spine surgery, using small and smoother cervical plates, using anchored spacers instead of plates, application of steroid before wound closure, performing arthroplasty instead of anterior cervical fusion for one-level disease, decreasing tracheal cuff pressure during medial retraction, using specific retractors, and changing the dissection plan.ConclusionsCurrent literature supports several preventative measures that may decrease the incidence of postoperative dysphagia. Although the evidence is limited and weak, most of these measures did not appear to increase other complications and can be easily incorporated into a surgical practice, especially in patients who are at high risk for postoperative dysphagia.     

Laryngeal Reflex before and after Placement of Airway Interventions: Endotracheal Tube and Laryngeal Mask Airway™

Background: Previous reports indicate that detrimental laryngeal function persists over several hours after tracheal extubation even in patients who have regained full consciousness from anesthesia. The authors hypothesize that even after minor surgery, the presence of an endotracheal tube (ETT) impairs the receptors at the vocal cord and diminishes the defensive laryngeal function. The hypothesis was tested by comparing types of experimentally induced laryngeal airway reflexes before and after surgery in anesthetized patients with use of either an ETT or a Laryngeal Mask Airway(TM).

Methods: Twenty adult patients undergoing elective minor surgeries were randomly allocated into two groups, the ETT and Laryngeal Mask Airway(TM) groups, depending on the airway management method used during surgery. While maintaining sevoflurane at 1 minimum alveolar concentration, laryngeal and respiratory responses were elicited by instillation of distilled water on the vocal cords immediately before and after surgery. Furthermore, the vocal cord angles were endoscopically measured under complete paralysis.

Results: Some laryngeal reflex responses of both groups, particularly the cough reflex, were significantly attenuated after minor surgery. Significant narrowing of the glottic aperture was evident in patients with ETT placement but not in patients with Laryngeal Mask Airway(TM) placement.     

Bilateral vocal cord paralysis after anterior cervical discoidectomy and fusion in a case of whiplash cervical spine injury: a case report

BACKGROUND

Bilateral vocal cord paralysis is a risk of anterior cervical discoidectomy and fusion. We discuss the mechanism of vocal cord paralysis and the precautions necessary to avoid this catastrophic complication. A rare case of bilateral vocal cord paralysis after anterior cervical discoidectomy and fusion (ACD/F) is reported.

CASE DESCRIPTION

The patient, a 37-year-old male, was paraplegic, had bilateral intrinsic hand muscle weakness and sphincter involvement following a whiplash cervical spinal injury. A C5-C6 ACD/F for traumatic C5-C6 disc prolapse was performed. On the third postoperative day, he developed difficulty in coughing and a husky voice. Otolaryngological evaluation revealed bilateral vocal cord paralysis. He later required a tracheostomy that partially alleviated his major symptoms.

CONCLUSION

In patients undergoing ACD/F, a mandatory preoperative evaluation of the vocal cords should be performed. An appropriate modification in surgical planning should be made if vocal cord palsy is diagnosed preoperatively to prevent bilateral vocal cord paralysis. Proper and judicious use of Cloward retractors is advocated.     

The Flex-Tip™ tracheal tube does not reduce the incidence of postoperative sore throat: a randomized controlled trial

Purpose

Sore throat after tracheal intubation is common with an incidence of 30-70%. The Parker Flex-Tip? endotracheal tube (ETT) is designed to reduce trauma during ETT placement. This randomized single-blinded trial was designed to assess whether using the Flex-Tip ETT would reduce the incidence of postoperative sore throat and/or vocal change.

Methods

A Flex-Tip or a Mallinckrodt Hi–Lo® cuffed ETT was used by random allocation in 200 patients with normal-appearing airways requiring elective orotracheal intubation. On the second postoperative day, a blinded assessor recorded the incidence and severity of postoperative sore throat and voice alteration. The primary outcome was the incidence of moderate or severe sore throat. Secondary outcomes included vocal change, time to intubation, number of attempts/failures, incidence of oropharyngeal bleeding, and subjective ease of intubation.

Results

Demographic data were similar between the two groups. Moderate or severe sore throat was observed in 12% of patients with the Flex-Tip ETT and 6% of patients with the Mallinckrodt Hi–Lo ETT (odds ratio [OR] 2.1; 95% confidence intervals [CI] 0.70 to 7.1; P = 0.14). The incidence of moderate or severe vocal change was 6% and 3%, respectively (OR 2.0; 95% CI 0.42 to 12.9; P = 0.50). Time to intubation, number of intubation attempts, incidence of oropharyngeal bleeding, and ease of intubation did not differ significantly between groups.

Conclusion

In this study involving experienced clinicians, no significant difference was observed in the incidence of postoperative sore throat or vocal change between the Flex-Tip ETT and the standard Mallinckrodt Hi-Lo cuffed ETT. This trial was registered at www.clinicaltrials.gov, NCT01095861.     

The supine-to-prone position change induces modification of endotracheal tube cuff pressure accompanied by tube displacement

Study ObjectivesTo determine whether the supine-to-prone position change displaced the endotracheal tube (ETT) and, if so, whether the displacement related to this change modified ETT cuff pressure.DesignProspective study.SettingOperating room of a university hospital.Patients132 intubated, adult, ASA physical status 1, 2, and 3 patients undergoing lumbar spine surgery.Interventions and MeasurementsAfter induction of anesthesia, each patient's trachea was intubated. The insertion depth of each ETT was 23 cm for men and 21 cm for women at the upper incisors. In the supine position and after the supine-to-prone position change with the head rotated to the right, the length from the carina to ETT tip and ETT cuff pressure were measured.Main ResultsAfter the supine-to-prone position change, 91.7% patients had ETT tube displacement. Of these, 48% of patients’ ETT moved ≥ 10 mm, whereas 86.3% of patients had changes in tube cuff pressure. There was a slight but significant correlation between ETT movement and change in cuff pressure. Depending on the position change, ETT cuff pressure decreased and the ETT tended to withdraw.ConclusionsAfter the supine-to-prone position change, patients had ETT tube displacement. Such ETT movement may be accompanied by a decrease in cuff pressure.     

Use of the video laryngoscopy for Combitube exchange in a difficult airway

Following failed intubation attempts via conventional direct laryngoscopy, an Esophageal Tracheal Combitube was successfully placed in the esophagus of a 51-year-old man with a subdural hematoma and uncleared cervical spine. The decision was made to change the Combitube for an endotracheal tube (ETT). After deflation of the large oropharyngeal cuff of the Combitube, video laryngoscopy was performed with the Direct Coupled Interface (DCI) video intubation system, and the Combitube was exchanged for an ETT with the assistance of a gum elastic bougie.     

Vocal fold immobility following burn intensive care.

OBJECTIVE: To evaluate factors associated with the development of vocal fold immobility in patients surviving burn intensive care. STUDY DESIGN AND SETTING: A retrospective review of patients referred to Department of Speech Pathology by the Burn Intensive Care Unit between June 2002 and November 2004. Patients underwent videostroboscopic examination, and associations of vocal fold immobility with factors related to patient management were examined by using logistic regression. RESULTS: Vocal fold immobility was diagnosed in 25 (48%) of the 52 patients evaluated. A significant association with a history of intubation during overseas aeromedical evacuation (odds ratio 4.5, P = 0.026) was observed. Multivariate modeling demonstrated an increased risk of 3% for each % total body surface area (TBSA) of burn. CONCLUSION: High-altitude transport of intubated patients was a significant risk factor in the development of laryngeal injury. SIGNIFICANCE: This study magnifies the role that endotracheal tube cuff pressure may play in recurrent laryngeal nerve injury.     

Elongation of the trachea during neck extension in children: implications of the safety of endotracheal tubes

During neck extension, the changes in distance between endotracheal tube (ETT) tip and carina may not be equal to the changes in distance between vocal cords and ETT tip because of tracheal elongation. These distances are directly related to extubation risk. Using a fiberoptic bronchoscope, the distance between ETT tip and carina was measured in the neutral position after full extension of the neck in 25 children (2-8 yr old) scheduled for elective surgery under general anesthesia. The tracheal length was then measured in the neutral position and after full extension. The distance between vocal cords and ETT tip was calculated as the tracheal length minus the distance between ETT tip and carina. After full extension, the tracheal length (7.97 +/- 0.85 cm) was increased by 0.95 +/- 0.43 cm, and the change in distance between vocal cords and ETT tip was -1.08 +/- 0.47 cm, whereas the change in distance between ETT tip and carina was 2.02 +/- 0.58 cm. These results suggest that neck extension actually displaces the ETT tip to the vocal cords, increasing the risk of tracheal extubation in older children, although the actual displacement of ETT tip to vocal cords is reduced by tracheal lengthening. IMPLICATIONS: The distance between endotracheal tube tip and vocal cords is directly related to the risk of exubation. Despite tracheal elongation, neck extension actually displaced the endotracheal tube tip to the vocal cords in older children.     

A new table-fixed soft tissue retractor for the anterior cervical spinal surgery

Summary Since surgeons sometimes encounter difficulty in keeping self-retaining soft tissue retractors in the proper position for anterior cervical spinal surgery, we have developed a new, simple soft tissue retractor system, which is fixed to the side rails of the operating table via retractor stands. All three joints of the retractor can be tightened simultaneously with a single handle. Each of two retractor blades can keep its position independent of the other thereby maintaining a well-exposed operative field for a long period of time. Fine adjustments of the blade position, after fixation of the retractors, is possible by sliding the head of the blade assembly along the axis of a ratchet mechanism. We have used these retractors in 43 surgical exposures, including 35 for anterior cervical fusion, 2 for posterior thoraco-lumbar decompression, and 6 for carotid endarterectomy. There have been no complications related to tissue damage.