Difficult direct laryngoscopy in patients with cervical spine disease

Preoperative radiological indicators for prediction of difficult laryngoscopy in patients with atlantoaxial dislocation

Background

Difficult airway remains a great challenge in patients with atlantoaxial dislocation (AAD). Preoperative evaluation and reliable prediction are required to facilitate the airway management. We aimed to screen out reliable radiological indicators for prediction of difficult laryngoscopy in patients with AAD.

Methods

A retrospective nested case-control study within a single center longitudinal AAD cohort was conducted to investigate the radiological indicators. All the patients with difficult laryngoscopy from 2010 to 2021 were enrolled as the difficult laryngoscopy group. Others in the cohort without difficult laryngoscopy were randomly selected as the non-difficult laryngoscopy group by individually matching with the same gender, same surgery year, and similar age (±5 years) at a ratio of 6:1. Radiological data on preoperative lateral X-ray images between the two groups were compared. Bivariate logistic regression model was applied to screen out the independent predictive indicators and calculate the odds ratios of indicators associated with difficult laryngoscopy. Receiver operating characteristic curve and area under the curve (AUC) were used to describe the discrimination ability of indicators.

Results

A total of 154 patients were finally analyzed in this study. Twenty-two patients with difficult laryngoscopy and matched with 132 controls. Four radiological parameters showed significant difference between the two groups. Among which, ΔC1C2D (the difference of the distance between atlas and axis in the neutral and extension position), owned the largest AUC.

Conclusions

ΔC1C2D could be a valuable radiologic predictor for difficult laryngoscopy in patients with AAD.

Identification of difficult laryngoscopy using an optimized hybrid architecture

BACKGROUND

Identification of difficult laryngoscopy is a frequent demand in cervical spondylosis clinical surgery. This work aims to develop a hybrid architecture for identifying difficult laryngoscopy based on new indexes.

METHODS

Initially, two new indexes for identifying difficult laryngoscopy are proposed, and their efficacy for predicting difficult laryngoscopy is compared to that of two conventional indexes. Second, a hybrid adaptive architecture with convolutional layers, spatial extraction, and a vision transformer is proposed for predicting difficult laryngoscopy. The proposed adaptive hybrid architecture is then optimized by determining the optimal location for extracting spatial information.

RESULTS

The test accuracy of four indexes using simple model is 0.8320. The test accuracy of optimized hybrid architecture using four indexes is 0.8482.

CONCLUSION

The newly proposed two indexes, the angle between the lower margins of the second and sixth cervical spines and the vertical direction, are validated to be effective for recognizing difficult laryngoscopy. In addition, the optimized hybrid architecture employing four indexes demonstrates improved efficacy in detecting difficult laryngoscopy.

TRIAL REGISTRATION

Ethics permission for this research was obtained from the Medical Scientific Research Ethics Committee of Peking University Third Hospital (IRB00006761-2015021) on 30 March 2015. A well-informed agreement has been received from all participants. Patients were enrolled in this research at the Chinese Clinical Trial Registry ( http://www.chictr.org.cn , identifier: ChiCTR-ROC-16008598) on 6 June 2016.

Perioperative and anesthetic management of patients with rheumatoid arthritis

Our understanding and management of rheumatoid arthritis (RA) have greatly improved, but perioperative and anesthetic management remain challenging. RA is not limited to joints; systemic evaluation is thus required when planning perioperative management. Especially, careful airway evaluation is needed; management of airway-related arthritis is challenging. A multidisciplinary approach is essential to prevent complications without exacerbating RA disease activity. Guidelines published in 2017 are available for perioperative management of anti-rheumatic medication in patients with rheumatic diseases undergoing elective total hip or total knee arthroplasty. However, the guidelines focus only on anti- rheumatic medications, and do not consider all aspects of perioperative management (including anesthesia). Here, we discuss the perioperative and anesthetic management of patients with RA.

Morphometric and ultrasonographic determinants of difficult laryngoscopy in obese patients: A prospective observational study

BACKGROUND

Obese people have a higher risk of difficult laryngoscopy due to their thick neck, large tongue, and redundant pharyngeal soft tissue. However, there is still no established predictive factor for difficult laryngoscopy in obese population.

METHODS

We conducted a prospective assessor-blind observational study to enroll adult patients with a body mass index of 30 kg·m-2 or higher undergoing laparoscopic sleeve gastrectomy at a medical center between May 2020 and August 2021. Conventional morphometric characteristics along with ultrasonographic airway parameters were evaluated before surgery. The primary outcome was difficult laryngoscopy, defined as a Cormack and Lehane's grade III or IV during direct laryngoscopy. Logistic regression analyses were performed to evaluate the association between included factors and difficult laryngoscopy. Discrimination performance of predictive factors was assessed using area under the receiver operating characteristic curve (AUC).

RESULTS

A total of 80 patients were evaluated, and 17 (21.3%) developed an event of difficult laryngoscopy. Univariate analyses identified five factors associated with difficult laryngoscopy, including age, sex, hypertension, neck circumference, and cross-sectional area of tongue base. After adjusting for these variables, neck circumference was the only independent influential factor, adjusted odds ratio: 1.227 (95% confidence interval, 1.009-1.491). Based on Youden's index, the optimal cutoff of neck circumference was 49.1 cm with AUC: 0.739 (sensitivity: 0.588, specificity: 0.889; absolute risk difference: 0.477, and number needed to treat: 3).

CONCLUSION

Greater neck circumference was an independent risk factor for difficult laryngoscopy in obese patients. This finding provides a way of reducing unanticipated difficult airway in this high-risk population.

Preoperative X-ray C2C6AR is applicable for prediction of difficult laryngoscopy in patients with cervical spondylosis

BACKGROUND

Airway management is one of the most important techniques in anesthesia practice and inappropriate airway management is related with airway injury, brain hypoxia, and even death. The patients with cervical spondylosis are often confronted with difficult laryngoscopy who are more prone to appear difficult airway, so it is important to figure out valuable predictors of difficult laryngoscopy in these patients.

METHODS

We randomly enrolled 270 patients undergoing elective cervical spine surgery and analyzed the cervical mobility data in predicting difficult laryngoscopy. The preoperative X-ray radiological indicators were measured by an attending radiologist. Cormack-Lehane scales were assessed during intubation, and patients with a class III or IV view were assigned to the difficult laryngoscopy group.

RESULTS

Univariate analysis showed that the hyomental distance (HMD, the distance between the hyoid bone and the tip of the chin) and the hyomental distance ratio (HMDR, the ratio between HMD in the extension position and the one in the neutral position) might not be suitable indicators in patients with cervical spondylosis. Binary multivariate logistic regression (backward-Wald) analyses identified two independent correlative factors from the cervical mobility indicators that correlated best as a predictor of difficult laryngoscopy: modified Mallampati test (MMT) and C₂C₆AR (the ratio of the angle between a line passing through the bottom of the second cervical vertebra and a line passing through the bottom of the sixth cervical vertebra in the extension position and the one in the neutral position). The odds ratio (OR) and 95 % CI were 2.292(1.093-4.803) and 0.493 (0.306-0.793), respectively. C₂C₆AR exhibited the largest area under the curve (0.714; 95 % CI 0.633-0.794).

CONCLUSIONS

C₂C₆AR based on preoperative X-ray images may be the most accurate predictor of cervical mobility indicators for difficult laryngoscopy in patients with cervical spondylosis.

TRIAL REGISTRATION

The study was registered at the Chinese Clinical Trial Registry ( http://www.chictr.org.cn ; identifier: ChiCTR-ROC-16,008,598) on June 6, 2016.

Assessment of Airway in Patients with Acromegaly Undergoing Surgery: Predicting Successful Tracheal Intubation

Background In the field of anesthesia, acromegaly is considered a cause of difficult tracheal intubation and airway management. There is a high probability of unanticipated difficult intubation in acromegalic patients despite a lower percentage of patients being identified preoperatively as having a difficult airway. In this study, we carried out various airway assessment tests preoperatively and during induction of anesthesia to find out the predictors of easy tracheal intubation in patients with acromegaly.

Methods All patients of either sex, diagnosed as a case of acromegaly and scheduled to undergo pituitary surgery were enrolled over a period of 3 years. Various airway assessment tests were performed prior to surgery, which included modified Mallampati (MP) classification (sitting and supine), mouth opening (MO), upper lip bite test (ULBT), neck movement (NM), thyromental (TM) distance, thyrohyoid (TH) distance, sternomental (SM) distance, hyomental (HM) distance, length of upper incisors (IL), receding mandible (RM), any history of obstructive sleep apnea (OSA), mask ventilation (MV), Cormack-Lehane (CL) III and IV, and external laryngeal manipulation (ELM). Results were reported as odds ratios (95% confidence interval [CI]). The p-value < 0.05 was considered statistically significant.

Results A total of 42 patients were enrolled over a period of 3 years. The male-to-female ratio was 19:23 with a mean age of 37.95 years and mean weight of 72.7 kg. Out of 15 airway assessment parameters, only ULBT and CL grade showed significant results.

Conclusion We conclude that ULBT and CL grading are reliable predictors of easy intubation in patients with acromegaly undergoing surgery.

Radiological indicators to predict the application of assistant intubation techniques for patients undergoing cervical surgery

Background

We aimed to distinguish the preoperative radiological indicators to predict the application of assistant techniques during intubation for patients undergoing selective cervical surgery.

Methods

A total of 104 patients were enrolled in this study. According to whether intubation was successfully accomplished by simple Macintosh laryngoscopy, patients were divided into Macintosh laryngoscopy group (n = 78) and Assistant technique group (n = 26). We measured patients’ radiographical data via their preoperative X-ray and MRI images, and compared the differences between two groups. Binary logistic regression model was applied to distinguish the meaningful predictors. Receiver operating characteristic (ROC) curve and area under the curve (AUC) were used to describe the discrimination ability of indicators. The highest Youden’s index corresponded to an optimal cut-off value.

Results

Ten variables exhibited significant statistical differences between two groups (P <  0.05). Based on logistic regression model, four further showed correlation with the application of assistant techniques, namely, perpendicular distance from hard palate to tip of upper incisor (X2), atlanto-occipital gap (X9), angle between a line passing through posterior-superior point of hard palate and the lowest point of the occipital bone and a line passing through the anterior-inferior point and the posterior-inferior point of the second cervical vertebral body (Angle E), and distance from skin to hyoid bone (MRI 7). Angle E owned the largest AUC (0.929), and its optimal cut-off value was 19.9° (sensitivity = 88.5%, specificity = 91.0%). the optimal cut-off value, sensitivity and specificity of other three variables were X2 (30.1 mm, 76.9, 76.9%), MRI7 (16.3 mm, 69.2, 87.2%), and X9 (7.3 mm, 73.1, 56.4%).

Conclusions

Four radiological variables possessed potential ability to predict the application of assistant intubation techniques. Anaesthesiologists are recommended to apply assistant techniques more positively once encountering the mentioned cut-off values.

Low skill fibreoptic intubation using i-gel™ and air-Q™ in simulated difficult airways: A randomised study in manikin and in patients

Background:

Fibreoptic intubation via a supraglottic device (SAD) is ‘low skill fibreoptic intubation’ (LSFOI). ‘Standard’ second generation SADs (i-gelTM) have a gastric port. ‘Specialised’ second generation SADs (air-QTM) are designed to facilitate LSFOI and have wider ventilation ports. Our hypothesis was that performance of LSFOI differs between i-gelTM and air-QTM in a manikin with a simulated difficult airway.

Methods:

Our primary outcome was fibreoptic intubation success rate. Our secondary outcomes included SAD insertion and LSFOI times. A difficult airway was simulated by applying a hard cervical collar to a manikin. Anaesthetists performed LSFOI serially using both SADs in a random sequence. In the manikin study, 80 anaesthetists were recruited. To test the robustness of the conclusion from our manikin study, we repeated the study in 22 anaesthetised patients. Patients were fitted with the same cervical collar and randomly allocated to either devices. We used McNemar’s statistical test to analyse our primary outcome of successful intubations and paired nominal data. A Wilcoxon signed-ranks test was used to analyse nonparametric paired data and a Mann–Whitney U test was used for unpaired data analysis where appropriate. A p-value of <0.05 was considered statistically significant.

Results:

In the manikin study, the i-gelTM was superior to the air-QTM for successful tracheal intubation (98.8% vs 83.8%, respectively; p=0.002) and LSFOI times (34.0 s vs 36.0 s, respectively; p=0.012). In the patient study, LSFOI success rates were not significantly different between i-gelTM and air-QTM (100% vs 91.6%, respectively; p=0.545) but intubation times were shorter (52.5 s vs 60.0 s, respectively; p=0.036).

Conclusion:

In conclusion, we obtained LSFOI success rates for the i-gelTM or air-QTM of 98.8% and 83.8% respectively in a manikin; and 100% and 91.6% respectively in patients. It is in fact ‘low skill’ as many participants were successful despite no prior experience with LSFOI. The i-gelTM is superior for LSFOI compared with the air-QTM. This is despite being a ‘standard’ second generation SAD as compared to a ‘specialised’ second generation SAD (air-QTM).

Trial Registration:

The manikin and patient studies were conducted after being approved by the SingHealth Centralised Institutional Review Board (CRB reference number 2014/2039 and 2016/2069, respectively). The patient study was registered at ClinicalTrials.gov (ID: NCT02663843).

An Anesthesiologist's Perspective on the History of Basic Airway Management: The "Modern" Era, 1960 to Present

This fourth and last installment of my history of basic airway management discusses the current (i.e., "modern") era of anesthesia and resuscitation, from 1960 to the present. These years were notable for the implementation of intermittent positive pressure ventilation inside and outside the operating room. Basic airway management in cardiopulmonary resuscitation (i.e., expired air ventilation) was de-emphasized, as the "A-B-C" (airway-breathing-circulation) protocol was replaced with the "C-A-B" (circulation-airway-breathing) intervention sequence. Basic airway management in the operating room (i.e., face-mask ventilation) lost its predominant position to advanced airway management, as balanced anesthesia replaced inhalation anesthesia. The one-hand, generic face-mask ventilation technique was inherited from the progressive era. In the new context of providing intermittent positive pressure ventilation, the generic technique generated an underpowered grip with a less effective seal and an unspecified airway maneuver. The significant advancement that had been made in understanding the pathophysiology of upper airway obstruction was thus poorly translated into practice. In contrast to consistent progress in advanced airway management, progress in basic airway techniques and devices stagnated.

Predictors of 30-Day Postoperative Pulmonary Complications After Open Reduction and Internal Fixation of Vertebral Fractures

OBJECTIVE

The purpose of this study was to identify predictors of 30-day postoperative pulmonary complications after open reduction and internal fixation (ORIF) of vertebral fractures.

METHODS

We performed a retrospective study using the American College of Surgeons National Surgical Quality Improvement Program database from 2010 to 2014. Adult patients who underwent ORIF of vertebral fractures were included and divided into 2 groups based on the occurrence of 30-day postoperative pulmonary complications. Baseline patient and operative characteristics were compared between the 2 groups. Multivariate regression (MVR) analysis was performed to identify independent risk factors for pulmonary complications.

RESULTS

A total of 900 patients were included in our cohort. The overall 30-day pulmonary complication rate was 5.67%. Patients who had a pulmonary complication after vertebral ORIF were more often men and more often had diabetes, functional dependence, American Society of Anesthesiologists score classification of 3 or higher, pulmonary comorbidity, renal comorbidity, and preoperative anemia. The pulmonary complication group also had a higher incidence of 30-day mortality, prolonged hospitalization, pneumonia, cardiac complications, urinary tract infection, blood transfusion, and sepsis. The MVR analysis found that pulmonary comorbidity (odds ratio [OR], 5.3; 95% confidence interval [CI], 2.5-11.5; P < 0.001), diabetes (OR, 2.1; 95% CI, 1.0-4.2; P = 0.037), partial or dependent functional status (OR, 4.7; 95% CI, 2.2-10.2; P < 0.001), and cervical spine involvement (OR, 3.6; 95% CI, 1.7-8.0; P = 0.001) were independent predictors of pulmonary complications.

CONCLUSIONS

Early identification of risk factors for postoperative pulmonary complications is important in the evaluation of patients with vertebral fractures for surgical decision-making, preoperative optimization, and subsequent postoperative care to improve patient outcomes and minimize morbidity.

Cervical Instability in Pierre Robin Sequence: An Addition to the Algorithm

Many patients with Pierre Robin sequence (PRS) have associated birth defects, most commonly in association with abnormalities in bone or cartilage formation. Depending on severity, treatment of PRS ranges from nonoperative management with prone positioning to surgical intervention such as distraction osteogenesis. Generally, if a surgical approach is needed, these patients undergo nasal endoscopy or direct laryngoscopy with their intubation, which puts the cervical spine in a position of extreme extension. The authors present a patient with syndromic PRS secondary to Sticklers syndrome, with a cervical abnormality diagnosed with three-dimensional computed tomography and further evaluated with dynamic lateral plain x-rays to assess cervical instability. The goal of this report is to highlight the need to include cervical spine evaluation in the preoperation workup of patients with PRS, especially those with suspected abnormalities in bone or collagen formation.

Shikani Optical Stylet versus Macintosh Laryngoscope for Intubation in Patients Undergoing Surgery for Cervical Spondylosis: A Randomized Controlled Trial

Background:

Airway management is critical in patients with cervical spondylosis, a population with a high incidence of difficult airway. Intubation with Shikani Optical Stylet (SOS) has become increasingly popular in difficult airway. We compared the effects of intubation with SOS versus Macintosh laryngoscope (MLS) in patients undergoing surgery for cervical spondylosis.

Methods:

A total of 270 patients scheduled for elective surgery for cervical spondylosis of spinal cord and nerve root type from August 2012 to January 2016 were enrolled and randomly allocated to the MLS or SOS group by random numbers. Patients were evaluated for difficult airway preoperatively, and Cormack-Lehane laryngoscopy classification was determined during anesthesia induction. Difficult airway was defined as Cormack-Lehane Grades III–IV. Patients were intubated with the randomly assigned intubation device. The success rate, intubation time, required assistance, immediate complications, and postoperative complaints were recorded. Categorical variables were analyzed by Chi-square test, and continuous variables were analyzed by independent samples t-test or rank sum test.

Results:

The success rate of intubation among normal airways was 100% in both groups. In patients with difficult airway, the success rates in the MLS and SOS groups were 84.2% and 94.1%, respectively (P = 0.605). Intubation with SOS took longer compared with MLS (normal airway: 25.1 ± 5.8 s vs. 24.5 ± 5.7 s, P = 0.426; difficult airway: 38.5 ± 8.5 s vs. 36.1 ± 8.2 s, P = 0.389). Intubation with SOS required less assistance in patients with difficult airway (5.9% vs. 100%, P < 0.001). The frequency of postoperative sore throat was lower in SOS group versus MLS group in patients with normal airway (22.0% vs. 34.5%, P = 0.034).

Conclusions:

SOS is a safe and effective airway management device in patients undergoing surgery for cervical spondylosis. Compared with MLS, SOS appears clinically beneficial for intubation, especially in patients with difficult airway.

Trial Registration:

Chinese Clinical Trial Registry, ChiCTR-IOR-16007821; http://www.chictr.org.cn/showproj.aspx?proj=13203.

Comparison of success of tracheal intubation using Macintosh laryngoscope-assisted Bonfils fiberscope and Truview video laryngoscope in simulated difficult airway

Background and Aims:

Restriction of head and neck movements prevents the alignment of the oral, pharyngeal, and laryngeal axes and increases the incidence of difficult tracheal intubation in patients with cervical spine fractures. Video laryngoscopes have gained an important role in the management of difficult intubation, especially in situations with limited head and neck movements. This study compares the success of intubation using Macintosh laryngoscope assisted Bonfils^® fiberscope (ML-BF) with Truview^PCD video laryngoscope (TV) in patients with simulated restricted head and neck movements.

Material and Methods:

One hundred and fifty-two patients satisfying the inclusion criteria were randomly allocated to two groups of 76 each. Patients were made to lie supine on the table without a pillow and a soft collar was used to restrict head and neck movements. After a standardized premedication-induction sequence, tracheal intubation was done either with ML-BF or TV. Success of intubation, time taken for successful intubation, hemodynamic changes, airway trauma, and postoperative oropharyngeal morbidity were noted.

Results:

Intubation was successful in all the 76 patients in direct laryngoscopy-Bonfils fiberscope group and 75 out of 76 patients in TV group within the specified time (90 s). The median time taken for successful intubation with TV and ML-BF were 44 (range 26–80) s and 49 (range 28–83) s, respectively. Hemodynamic changes, airway trauma, and postoperative oropharyngeal morbidity were similar in both groups.

Conclusion:

Both TV and ML-BF are equally effective for successful tracheal intubation in patients with simulated restricted head and neck movements. In cases of difficult laryngeal visualization with routine Macintosh laryngoscope, Bonfils can be used as an adjunct to achieve successful intubation in the same laryngoscopy attempt.

Hyomental distance in the different head positions and hyomental distance ratio in predicting difficult intubation

The hyomental distance ratio (HMDR) is the ratio between the hyomental distance (HMD) (the distance between the hyoid bone and the tip of the chin) at the extreme of head extension (HMDe) and the one in the neutral position (HMDn). The objective of the study was to examine the predictive value, sensitivity, and specificity of HMDe, HMDn, and HMDR in predicting difficult endotracheal intubation (DI). A prospective study included 262 patients that underwent elective surgical operations. The following parameters were observed as possible predictors of DI: HMDR, HMDe, HMDn, Mallampati score, and body mass index (BMI). The cut-off points for the DI predictors were HMDe <5.3 cm, HMDn ≤5.5 cm, and HMDR ≤1.2. The assessment that DI existed was made by the anesthesiologist while performing laryngoscopy by applying the Cormack-Lehane classification. DI was present in 13 patients (5%). No significant difference was observed in the frequency of DI with regard to the sex, age, and BMI of the patients. Our research indicated HMDR as the best predictor of DI with a sensitivity of 95.6% and specificity of 69.2%. HMDR can be used in the everyday work of anesthesiologists because HMDR values ≤1.2 may reliably predict DI.

Head and neck surgery in a tertiary centre: Predictors of difficult airway and anaesthetic management

Introduction:

The management of head and neck surgical patients is associated with increased morbidity and mortality, and so anticipating the difficult airway is important.

Methods:

We undertook a prospective survey on consecutive adult patients scheduled on the elective operating lists of four head and neck consultant surgeons. Data were collected over a 36 month period. Data included: patient characteristics; routine predictors of difficulty in airway management (bedside tests of the airway, a history of previous surgery or radiotherapy and the presence of airway symptoms); laryngoscopy grade; method of anaesthesia and airway management; and any airway complications arising during induction of anaesthesia and extubation.

Results:

The ‘study’ group consisted of 818 patients. The ‘direct laryngoscopy’ group contained 674 patients, that is, patients who had direct laryngoscopy and could therefore be classified as easy or difficult intubation. The prevalence of difficult intubation was 12.6%. Factors or tests that were statistically significantly associated with difficult intubation were: history of difficult airway; previous head or neck radiotherapy treatment; presence of airway symptoms; presence of moderate or severe limited neck movement; and short interdental distance. The sensitivity, specificity and positive predictive values were: history of difficult airway 16.5%, 98.6% and 63.6%; previous radiotherapy 12.9%, 96.6% and 35.5%; airway symptoms 42.9%, 69.6% and 15.9%; moderate/severe neck limitation 16.7%, 97.2% and 46.7%; Mallampati score 3 or 4, 38.8%, 83.8% and 25.8%; and interdental distance 9.4%, 98.8% and 53.3%, respectively. The Bonfils intubation fibrescope was the most commonly used indirect laryngoscopy device (63.9% of all such cases). Twenty-six patients (3.2%) had complications during their initial airway management after induction of anaesthesia. There was one case of ‘cannot intubate, cannot oxygenate’, which required an emergency tracheostomy.

Conclusion:

The prevalence of difficult intubation in head and neck surgical patients was higher than in the general population, but predictive tests for difficult intubation have poor to moderate value. In our study, rates of difficult face mask ventilation, failed intubation and complications during induction and extubation were low. However, serious morbidity, although rare, can still be encountered. Head and neck surgical patients can be managed safely in a tertiary centre where there is appropriate surgical and anaesthetic expertise in managing difficult airways.

Predictors of difficult intubation and the otolaryngology perioperative consult

Airway management is one of the most important aspects of anesthesia care. Although the incidence of difficult intubation is low, predicting a potentially difficult airway can ensure that necessary staff and equipment are available. A preoperative airway evaluation should include a history and physical examination focusing on elements that can cause problems with intubation. When indicated, flexible fiberoptic laryngoscopy can add valuable information regarding the upper aerodigestive anatomy. Specific patient and situational factors should be considered. Alternative plans should be defined before the initiation of anesthesia. Management of a complex airway should be a coordinated effort between anesthesiologists and otolaryngologists.

Neurological deterioration during intubation in cervical spine disorders

Anaesthesiologists are often involved in the management of patients with cervical spine disorders. Airway management is often implicated in the deterioration of spinal cord function. Most evidence on neurological deterioration resulting from intubation is from case reports which suggest only association, but not causation. Most anaesthesiologists and surgeons probably believe that the risk of spinal cord injury (SCI) during intubation is largely due to mechanical compression produced by movement of the cervical spine. But it is questionable that the small and brief deformations produced during intubation can produce SCI. Difficult intubation, more frequently encountered in patients with cervical spine disorders, is likely to produce greater movement of spine. Several alternative intubation techniques are shown to improve ease and success, and reduce cervical spine movement but their role in limiting SCI is not studied. The current opinion is that most neurological injuries during anaesthesia are the result of prolonged deformation, impaired perfusion of the cord, or both. To prevent further neurological injury to the spinal cord and preserve spinal cord function, minimizing movement during intubation and positioning for surgery are essential. The features that diagnose laryngoscopy induced SCI are myelopathy present on recovery, short period of unconsciousness, autonomic disturbances following laryngoscopy, cranio-cervical junction disease or gross instability below C3. It is difficult to accept or refute the claim that neurological deterioration was induced by intubation. Hence, a record of adequate care at laryngoscopy and also perioperative period are important in the event of later medico-legal proceedings.

Head elevation improves laryngeal exposure with direct laryngoscopy

STUDY OBJECTIVE

The aim of this study was to examine the effect of changing head position on the laryngeal view in the same subject.

DESIGN

Prospective, randomized, crossover comparison of laryngeal views.

SETTING

Operating suite at a university-affiliated, community hospital.

PATIENTS

One hundred sixty-seven consenting adult patients scheduled to undergo elective surgery with general anesthesia.

INTERVENTIONS

After anesthesia induction and muscle relaxation and the head in extended position, the laryngeal view was graded in 3 different head height positions. A special inflatable pillow was placed under the subject's head before induction and was deflated to produce no head elevation or inflated to produce either 6.0cm (sniffing position), or 10.0cm elevation (elevated sniffing position) in random order.

MAIN RESULTS

The incidence of difficult laryngoscopy (grade ≥3) was 8.38% with no head elevation, 2.39% in the sniffing position, and 1.19% in the elevated sniffing position. Head elevation was not associated with a worse grade in any single patient.

CONCLUSIONS

Sniffing position improves glottic exposure when the laryngoscopic grade is greater than 1 in the head-flat position. The elevated sniffing position improves the view to a better grade in some patients. Because head elevation was not associated with a worse grade in any subject, the elevated sniffing position should be considered as the initial head position before direct laryngoscopy when a difficult exposure is anticipated.

Endotracheal tube intubation with the aid of a laryngeal mask airway, a fiberoptic bronchoscope, and a tube exchanger in a difficult airway patient: a case report

A 28-year-old male patient with occipito-atlanto-axial instability underwent a cervical fusion with posterior technique. Post-operatively, the endotracheal tube (ETT) was removed, and the patient was transferred to the intensive care unit. After transfer, an upper airway obstruction developed and reintubations with a laryngoscope were attempted but failed. We inserted a #4 proseal laryngeal mask airway (LMA) and passed a 5.0 mm ETT through the LMA with the aid of a fiberoptic bronchoscope. We passed a tube exchanger through the 5.0 mm ETT and exchanged it with a 7.5 mm ETT. This method may be a useful alternative for difficult tracheal intubations.

Thyromental height: a new clinical test for prediction of difficult laryngoscopy

BACKGROUND

The incidence of difficult laryngoscopy is reported in the range of 1.5% to 20%. We hypothesized that there is a close association between the occurrence of difficult laryngoscopy and the height between the anterior borders of the mentum and thyroid cartilage, while the patient lies supine with her/his mouth closed. We have termed this the "thyromental height test" (TMHT). Our aim in this study was to determine its utility in predicting difficult laryngoscopy.

METHODS

Three hundred fourteen consecutive male and female patients aged ≥ 16 years scheduled to undergo general anesthesia were invited to participate. Airway assessments were performed with the modified Mallampati test, thyromental distance and sternomental distance, and TMHT in the preoperative clinic. Afterward, Cormack and Lehane grade of laryngoscopy views was assessed during intubation. The laryngoscopist was unaware of airway assessments. As a primary end point, the validity and prediction indexes for the TMHT were calculated. Calculation of validity indexes for the 3 other methods of airway assessment was a secondary objective of this study.

RESULTS

The optimal sensitivity and specificity values were in the range of 47.46 to 51.02 mm. To facilitate clinical application, a cutoff value equal to 50 mm was chosen. TMHT was more accurate than the other tests (all P < 0.0001).

CONCLUSIONS

The TMHT appears to be a more accurate predictor of difficult laryngoscopy than the existing anatomical measurements.

Anesthetic considerations in acute spinal cord trauma

Patients with actual or potential spinal cord injury (SCI) are frequently seen at adult trauma centers, and a large number of these patients require operative intervention. All polytrauma patients should be assumed to have an SCI until proven otherwise. Pre-hospital providers should take adequate measures to immobilize the spine for all trauma patients at the site of the accident. Stabilization of the spine facilitates the treatment of other major injuries both in and outside the hospital. The presiding goal of perioperative management is to prevent iatrogenic deterioration of existing injury and limit the development of secondary injury whilst providing overall organ support, which may be adversely affected by the injury. This review article explores the anesthetic implications of the patient with acute SCI. A comprehensive literature search of Medline, Embase, Cochrane database of systematic reviews, conference proceedings and internet sites for relevant literature was performed. Reference lists of relevant published articles were also examined. Searches were carried out in October 2010 and there were no restrictions by study design or country of origin. Publication date of included studies was limited to 1990–2010.

Mechanical airway obstruction due to dislodged spinal hardware

A difficult airway caused by mechanical obstruction from dislodged spinal hardware in a patient undergoing revision surgery for a cervical chordoma is presented. Due to the logical, sequential multidisciplinary airway and patient management by the anesthesiology, neurosurgery, and otolaryngology teams working together in an environment of clear communication, a potential life-threatening crisis was averted with successful outcome for the patient.

Rheumatoid arthritis and anaesthesia

There has been a great deal of progress in our understanding and management of rheumatoid arthritis in recent years. The peri-operative management of rheumatoid arthritis patients can be challenging and anaesthetists need to be familiar with recent developments and potential risks of this multi system disease.

Examination of Submental Space as an Alternative Method of Airway Assessment (Submental Sign)

Background

Difficult airway especially failed intubation has been associated with a high incidence of mortality and morbidity. Most of mortalities occur when an anaesthesiologist encounters an unanticipated difficult airway.

Findings

In 1999, a 23 yr. old, 65 kg weight and 170 cm height female patient had been scheduled for arthroscopy. Despite totally normal airway assessment (thyromental distance, mouth opening, jaw and neck movement ...) I was astonished by encountering a grade IV Cormack - Lehane laryngoscopic view. Tracheal intubation was impossible and ventilation was very difficult.

On attempt to attain a better laryngoscopic view, while manipulating submandibular region I encountered a bulky noncompliant submental space (Submental Sign). This event made me more alert regarding this finding. Thereafter I noted for this sign throughout the past years and I found it very helpful.

These findings encouraged me to write this report, and suggest a routine examination of submental space in order to keep the safety of the patient at the heart of the care we provide.

Conclusion

Evaluation of the submental space is suggested as an alternative predictor of difficult airway and routine examination of the submental space is of value in airway assessment.

Evaluation of laryngoscopic views and related influencing factors in a pediatric population

BACKGROUND

Management of the difficult pediatric airway is a serious problem that anesthesiologists face in their practice. However, guidelines for adults may not be applied readily to pediatric populations.

AIM

This study was performed to determine the incidence of different laryngoscopic views and the associated conditions.

METHODS

The authors collected data on 511 consecutive patients who were scheduled to receive general anesthesia. Laryngeal views were graded using the Cormack and Lehane classification, and grades III and IV were defined as difficult laryngoscopic visualization. The distances from the nose to the upper lip, lower lip to menthom, ear tragus to mouth, ear lobe to mouth, the horizontal length of mandible, and thyromental distance were measured. The association of these parameters with the laryngoscopic views was analyzed.

RESULTS

The incidence of grade I to IV laryngoscopic views was 80%, 17%, 3%, and 0%, respectively. All the cases that involved difficult laryngoscopy (3%) were aged ≤3 months. The distances from the lower lip to menthom and ear tragus to mouth had a direct association with difficult cases. There were no apparent cutoff points to predict difficult laryngoscopy, for any of the distances.

CONCLUSION

The difficult cases were mostly aged <1 year. The association between difficult laryngoscopy and the distances between the lower lip border and menthom, ear tragus and corner of the mouth, and ear lobe and corner of the mouth can be summarized in an equation that may have potential use in the prediction of difficult laryngoscopy.

Motion of a cadaver model of cervical injury during endotracheal intubation with a Bullard laryngoscope or a Macintosh blade with and without in-line stabilization

BACKGROUND

Endotracheal intubation in patients with potential cervical injury is a common dilemma in trauma. Although direct laryngoscopy (DL) with manual in-line stabilization (MILS) is a standard technique there is little data on the effect of MILS on cervical motion. Likewise there is little data available regarding alternative airway techniques in this setting. This study compared intubations with and without MILS in a cadaver model of cervical instability. We also used this model to compare intubations using DL with a Macintosh blade versus a Bullard laryngoscope (BL).

METHODS

Complete C4-C5 disarticulations were surgically created in 10 fresh human cadavers. The cadavers were then intubated in a random order with either BL or DL with and without MILS. The motion at the unstable interspace was measured for subluxation, angulation, and distraction.

RESULTS

MILS did not significantly affect maximal motion of this model in any of the three measures using either DL or BL. There were no clinically significant differences in maximal median motion in any of the three measures when comparing the two blades. However, there was significantly more variance in the subluxation caused by DL than by BL.

CONCLUSIONS

We were unable to demonstrate any significant effect of MILS on the motion of an unstable cervical spine in this cadaver model. The BL appears to be a viable alternative to DL in the setting of an unstable lower cervical spine.

The difficult airway in adult critical care

INTRODUCTION

The difficult airway is a common problem in adult critical care patients. However, the challenge is not just the establishment of a safe airway, but also maintaining that safety over days, weeks, or longer.

AIMS

This review considers the management of the difficult airway in the adult critical care environment. Central themes are the recognition of the potentially difficult airway and the necessary preparation for (and management of) difficult intubation and extubation. Problems associated with tracheostomy tubes and tube displacement are also discussed.

RESULTS

All patients in critical care should initially be viewed as having a potentially difficult airway. They also have less physiological reserve than patients undergoing airway interventions in association with elective surgery. Making the critical care environment as conducive to difficult airway management as the operating room requires planning and teamwork. Extubation of the difficult airway should always be viewed as a potentially difficult reintubation. Tube displacement or obstruction should be strongly suspected in situations of new-onset difficult ventilation.

CONCLUSIONS

Critical care physicians are presented with a significant number of difficult airway problems both during the insertion and removal of the airway. Critical care physicians need to be familiar with the difficult airway algorithms and have skill with relevant airway adjuncts.

Left molar approach improves laryngeal view in patients with simulated limitation of cervical movements

BACKGROUND

Immobilized cervical spine, because of either diseases or stabilizing devices, poses considerable difficulties with endotracheal intubation due to poor laryngoscopic view. The left molar (LM) approach has been shown to be useful in difficult sporadic intubation cases. We evaluated efficacy of this approach of laryngoscopy to improve laryngeal view in patients with simulated limitation of cervical movements.

METHODS

Thirty patients of American Society of Anesthesiologists grade I/II, who were scheduled to undergo routine surgical procedures under general anaesthesia and endotracheal intubation, were studied. A two-piece semi-rigid cervical collar was used to immobilize the cervical spine. Under standardized anaesthesia and neuromuscular blocking agent, conventional laryngoscopy using a curved Macintosh blade was performed and glottic view was recorded with and without optimal external laryngeal manipulation (OELM). Subsequently, in the same subjects the laryngoscope blade was withdrawn and re-inserted through the LM approach and glottic view was recorded with and without OELM followed by tracheal intubation.

RESULTS

With the conventional approach, laryngeal view was recorded as grade II in five patients, grade III in 24 patients, and grade IV in one patient. However, with the LM approach, laryngeal view was grade I in 25 patients, grade II in five patients, and grade III or IV in none (P<0.001). Tracheal intubation with the LM approach required the use of a flexible stylet to guide the tube tip into the larynx.

CONCLUSIONS

The laryngeal view is improved by the LM approach in patients with simulated limited cervical movements with a high success rate of tracheal intubation, but requires orientation for negotiation of the tube through the narrow oropharyngeal space available.

Predictors of difficult intubation in patients with cervical spine limitations

BACKGROUND

Cervical spine function is of paramount importance to the management of the airway. What has not been reported in the literature is a systematic analysis of airway management in patients with cervical spine limitation (CSL) compared with their normal counterparts or a predictive model of difficult intubation (DI) in patients with CSL.

METHODS

We reviewed the electronic charts of 14,053 patients and identified those with CSL based on the preoperative airway evaluation. We then compared various airway parameters in patients with CSL to those without CSL and further assessed risk factors for DI in patients with CSL. We develop a predictive model on the basis of multivariate analysis of such risk factors.

RESULTS

Of the cohort studied, 1145 or 8.1% of patients were documented as having some form of CSL, with an average age of 60. In the <60 population, CSL was associated with a statistically significant increase in difficult and impossible mask ventilation, difficult laryngoscopy, and DI. In the population > or =60 years old, CSL was associated with a statistically significant increase in difficult laryngoscopy and DI. There were no significant differences in mask ventilation between normal and CSL patients in the population > or =60. Multivariate modeling revealed age > or =48, Mallampati 3 or 4, and thyromental distance <6 cm as independent preoperative risk factors of DI in patients with CSL. A predictive model is developed on the basis of these findings.

CONCLUSIONS

Limitations of cervical spine mobility are relatively common and increase the incidence of difficulty throughout the spectrum of airway management. DI should be anticipated in CSL patients who are > or =48 years old, have a Mallampati class 3 or 4, and a thyromental distance of <6 cm.

Poor visualization during direct laryngoscopy and high upper lip bite test score are predictors of difficult intubation with the GlideScope videolaryngoscope

BACKGROUND

The GlideScope videolaryngoscope allows equal or superior glottic visualization compared with direct laryngoscopy, but predictive features for difficult GlideScope intubation have not been identified. We undertook this prospective study to identify patient characteristics associated with difficult GlideScope intubation.

METHODS

Demographic and morphometric factors were recorded preoperatively for 400 patients undergoing anesthesia with endotracheal intubation. After induction, direct laryngoscopy was performed in all patients to assess the Cormack and Lehane grade of glottic visualization followed by GlideScope intubation. The number of attempts and time needed for intubation were recorded. Univariate and multivariate analyses were performed to identify the characteristics associated with difficult GlideScope intubation.

RESULTS

Intubation required 1, 2, and 3 attempts in 342, 48, and 9 participants, respectively, with one failure. Mean time for intubation was 21 +/- 14 s. After univariate analysis, the following characteristics were significantly correlated (P < 0.05) with longer time to intubate and/or multiple attempts: older age, male sex, history of snoring, high Mallampati class, small mouth opening, short sternothyroid and manubriomental distances, large neck circumference, high upper lip bite test score, and high Cormack and Lehane grade during direct laryngoscopy. However, after introducing these variables in nominal logistic and proportional hazard multiple regression models, only high Cormack and Lehane grade during direct laryngoscopy, high upper lip bite test score, and short sternothyroid distance were significantly associated with multiple attempts or lengthier intubations.

CONCLUSION

Despite a high success rate, intubation with the GlideScope is likely to be more challenging in patients with high Cormack and Lehane grade during direct laryngoscopy, high upper lip bite test score, or short sternothyroid distance.

Considerations for airway management for cervical spine surgery in adults

Surgery on the cervical spine runs the gamut from minor interventions done in a minimally invasive fashion on a short-stay or ambulatory basis, to major surgical undertakings of a high-risk, high-threat nature done to stabilize a degraded skeletal structure to preserve and protect neural elements. Planning for optimum airway management and anesthesia care is facilitated by an appreciation of the disease processes that affect the cervical spine and their biomechanical implications and an understanding of the imaging and operative techniques used to evaluate and treat these conditions. This article provides background information and evidence to allow the anesthesia practitioner to develop a conceptual framework within which to develop strategies for care when a patient is presented for surgery on the cervical spine.