Various anatomical measurements and non-invasive clinical tests, singly or in various combinations can be performed to predict difficult intubation. Recently introduced “Upper lip bite test” (ULBT) and “Ratio of height to Thyromental distance” (RHTMD) are claimed to have high predictability. We conducted a study to compare the Predictive Value of ULBT and RHTMD with Mouth opening (Inter-Incisor gap) (IIG), Modified Mallampatti Test (MMT), Head and neck movement (HNM) and Thyromental Distance (TMD) for Difficult Laryngoscopy.
Materials and Methods:
In this prospective, single blinded observational study, 480 adult patients of either sex, ASA grade I and II were assessed and graded for ULBT, RHTMD, TMD, MMT, IIG, and HNM according to standard methods and correlated with the Cormack and Lehane grade.
ULBT and RHTMD had highest sensitivity, specificity, positive predictive value, negative predictive value, likelihood ratio, i.e., 74.63%, 91.53%, 58.82%, 95.7%, 31.765 and 71.64%, 92.01%, 59.26%, 95.24%, 8.96 respectively, compared to TMD, MMT, IIG and HNM.
ULBT is the best predictive test for difficult laryngoscopy in apparently normal patients but RHTMD can also be used as an acceptable alternative.
Airway assessment tests; difficult laryngoscopy; ratio of height to thyromental distance; upper lip bite test
The intubation difficulty scale (IDS) has been used as a validated difficulty score to define difficult intubation (DI). The purpose of this study is to identify airway assessment factors and total airway score (TAS) for predicting DI defined by the IDS.
There were 305 ASA physical status 1-2 patients, aged 19-70 years, who underwent elective surgery with endotracheal intubation. During the pre-anesthetic visit, we evaluated patients by 7 preoperative airway assessment factors, including the following: Mallampati classification, thyromental distance, head & neck movement, body mass index (BMI), buck teeth, inter-incisor gap, and upper lip bite test (ULBT). After endotracheal intubation, patients were divided into 2 groups based on their IDS score estimated with 7 variables: normal (IDS < 5) and DI (IDS ≥ 5) groups. The incidence of TAS (> 6) and high score of each airway assessment factor was compared in two groups: odds ratio, confidence interval (CI) of 95%, with a significant P value ≤ 0.05.
The odds ratio of TAS (> 6), ULBT (class III), head & neck movement (< 90°), inter-incisor gap (< 4 cm), BMI (≥ 25 kg/m2) and Mallampati classification (≥ class III) were respectively 13.57 (95% CI = 2.99-61.54, P < 0.05), 12.48 (95% CI = 2.50-62.21, P < 0.05), 3.11 (95% CI = 0.87-11.13), 2.32 (95% CI = 0.75-7.19), 2.22 (95% CI = 0.81-6.06), and 1.22 (95% CI = 0.38-3.89).
We suggest that TAS (> 6) and ULBT (class III) are the most useful factors predicting DI.
Anesthesia; Evaluation studies; Intubation
There are numerous reports of difficult laryngoscopy and intubation in patients with acromegaly. To date, no study has assessed the application of extended Mallampati score (EMS) for predicting difficult intubation in acromegalics. The primary aim of this study was to compare EMS with modified Mallampati classification (MMP) in predicting difficult laryngoscopy in acromegalic patients. We hypothesized that since EMS has been reported to be more specific and better predictor than MMP, it may be superior to the MMP to predict difficult laryngoscopy in acromegalic patients.
Materials and Methods:
For this prospective cohort study with matched controls, acromegalic patients scheduled to undergo pituitary surgery over a period of 3 years (January 2008-December 2010) were enrolled. Preoperative airway assessment was performed by experienced anesthesiologists and involved a MMP and the EMS. Under anesthesia, laryngoscopic view was assessed using Cormack-Lehane (CL) grading. MMP and CL grades of I and II were defined “easy” and III and IV as “difficult”. EMS grade of I and II were defined “easy” and III as “difficult”. Data were used to determine the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of MMP and EMS in predicting difficult laryngoscopy.
Seventy eight patients participated in the study (39 patients in each group). Both MMP and EMS failed to detect difficult laryngoscopy in seven patients. Only one laryngoscopy was predicted to be difficult by both tests which was in fact, difficult.
We found that addition of neck extension did not improve the predictive value of MMP.
Acromegaly; airway; extended Mallampati score; Mallampati classification
The incidence of difficulty in tracheal intubation has been reported to range from 0.5 to 18% in patients undergoing surgery. We aimed to elucidate the role of upper lip bite test (ULBT) with other prevailing tests, hyomental/thyrosternal distances (HMD/TSD), and the mandible length (ML) and their possible correlation in predicting difficulty in intubation. After institutional approval and informed consent were obtained, 300 consecutive patients aged 20–60 years of ASA physical status I and II, scheduled for elective surgical procedures requiring tracheal intubation and meeting the inclusion criteria, were enrolled in this study. Each patient was evaluated regarding ULBT, HMD, TSD and ML. Laryngoscopy was assessed by an attending anaesthesiologist blinded to the measurements. The laryngoscopic result was graded according to Cormack and Lehane’s Grading system. The negative predictive value (NPV) and positive predictive value (PPV) of ULBT were found to be 94 and 100%, respectively. These corresponding figures for TSD were 88.5 and 0%, respectively. Specificities for ULBT, HMD, ML and TSD were 100, 98.9, 98.9 and 98.1%, respectively. ULBT class and laryngoscopic grading showed the greatest agreement (kappa = 0.61, P < 0.001). An agreement between laryngoscopic grading and HMD and ML also existed (0.003 and <0.001, respectively), but was comparatively weaker. The high specificity, NPV, PPV and accuracy of ULBT as revealed in this study could be a good rationale for its application in the prediction of difficulty or easiness in intubation. ML > 9 cm and HMD > 3.5 cm were good predictors of negative difficult intubation.
Difficult intubation; difficult laryngoscopy; endotracheal intubation; predictive airway tests
The incidence of difficult laryngoscopy and intubation in obese patients is higher than in the general population. Classical predictors of difficult laryngoscopy and intubation have been shown to be unreliable. We prospectively evaluated indirect mirror laryngoscopy as a predictor of difficult laryngoscopy in obese patients.
Materials and Methods:
60 patients with a body mass index (BMI) greater than 30, scheduled to undergo general anesthesia, were enrolled. Indirect mirror laryngoscopy was performed and was graded 1-4 according to Cormack and Lehane. A view of grade 3-4 was classified as predicting difficult laryngoscopy. Additional assessments for comparison were the Samsoon and Young modification of the Mallampati airway classification, Wilson Risk Sum Score, neck circumference, and BMI. The view obtained upon direct laryngoscopy after induction of general anesthesia was classified according to Cormack and Lehane as grade 1-4.
Sixty patients met the inclusion criteria; however, 8 (13.3%) patients had an excessive gag reflex, and examination of the larynx was not possible. 15.4% of patients who underwent direct laryngoscopy had a Cormack and Lehane grade 3 or 4 view and were classified as difficult. Mirror laryngoscopy had a tendency toward statistical significance in predicting difficult laryngoscopy in these patients.
This study is consistent with previous studies, which have demonstrated that no one individual traditional test has proven to be adequate in predicting difficult airways in the obese population. However, the new application of an old test - indirect mirror laryngoscopy - could be a useful additional test to predict difficult laryngoscopy in obese patients.
Difficult airway; mirror indirect laryngoscopy; obesity; prediction
Failure to maintain a patent airway is one of the commonest causes of anesthesia-related morbidity and mortality. Many protocols, algorithms, and different combinations of tested methods for airway assessment have been developed to predict difficult laryngoscopy and intubation. The reported incidence of a difficult intubation varies from 1.5% to 13%. The objective of this study was to compare Mallampati test (MT) with lower jaw protrusion (LJP) maneuver in predicting difficult laryngoscopy and intubation.
Materials and Methods:
Seven hundred and sixty patients were included in the study. All the patients underwent MT and LJP maneuver for their airway assessment. After a standardized technique of induction of anesthesia, primary anesthetist performed laryngoscopy and graded it according to the grades described by Cormack and Lehane. Sensitivity, specificity, accuracy, and positive predictive value (PPV) and negative predictive value (NPV) were calculated for both these tests with 95% confidence interval (CI) using conventional laryngoscopy as gold standard. Area under curve was also calculated for both, MT and LJP maneuver. A P < 0.05 was taken as significant.
LJP maneuver had higher sensitivity (95.9% vs. 27.1%), NPV (98.7% vs. 82.0%), and accuracy (90.1% vs. 80.3%) when compared to MT in predicting difficult laryngoscopy and intubation. Both tests, however, had similar specificity and PPV. There was marked difference in the positive and negative likelihood ratio between LJP and MT. Similarly, the area under the curve favored LJP maneuver over MT.
The results of this study show that LJP maneuver is a better test to predict difficult laryngoscopy and tracheal intubation. We recommend the addition of this maneuver to the routine preoperative evaluation of airway.
Airway; difficult intubation; lower jaw protrusion maneuver; Mallampati test
Prediction of difficult laryngoscopy in obese patients is challenging. In 50 morbidly obese patients, we quantified the neck soft tissue from skin to anterior aspect of trachea at the vocal cords using ultrasound. Thyromental distance <6 cm, mouth opening <4 cm, limited neck mobility, Mallampati score >2, abnormal upper teeth, neck circumference >45 cm, and sleep apnoea were considered predictors of difficult laryngoscopy. Of the nine (18%) difficult laryngoscopy cases, seven had obstructive sleep apnoea history; whereas, only 2 of the 41 easy laryngoscopy patients did (P<0.001). Difficult laryngoscopy patients had larger neck circumference [50 (3.8) vs. 43.5 (2.2) cm; P<0.001] and more pre-tracheal soft tissue [28 (2.7) mm vs. 17.5 (1.8) mm; P<0.001] [mean (SD)]. Soft tissue values completely separated difficult and easy laryngoscopies. None of the other predictors correlated with difficult laryngoscopy. Thus, an abundance of pretracheal soft tissue at the level of vocal cords is a good predictor of difficult laryngoscopy in obese patients.
Anaesthesia; Neck; Obesity; Ultrasound
This study evaluated the performance of modified Mallampati score, 3-3-2 rule and palm print in prediction of difficult intubation.
In a prospective descriptive study, data from 500 patients scheduled for elective surgery under general anesthesia were collected. An anesthesiologist evaluated the airway using mentioned tests and another anesthesiologist evaluated difficult intubation. Laryngoscopic views were determined by Cormack and Lehane score. Grades 3 and 4 were defined as difficult intubation. Sensitivity, specificity, positive predictive value, negative predictive value and Youden index were determined for all tests.
Difficult intubation was reported in 8.9% of the patients. There was a significant correlation between body mass index and difficult intubation (P : 0.004); however, other demographic characteristics didn’t have a significant correlation with difficult intubation. Among three tests, palm print was of highest specificity (96.46%) and modified Mallampati of highest sensitivity (98.40%). In a combination of the tests, the highest specificity, sensitivity and Youden index were observed when using all three tests together.
Palm print has a high specificity for prediction of difficult intubation, but the best way for prediction of difficult intubation is using all three tests together.
Difficult intubation; modified Mallampati score; palm print; 3-3-2 rule
Background: Clinical detection of structural narrowing of the upper airway may facilitate early recognition of obstructive sleep apnoea (OSA). To determine whether the craniofacial profile predicts the presence of OSA, the upper airway and craniofacial structure of 239 consecutive patients (164 Asian and 75 white subjects) referred to two sleep centres (Hong Kong and Vancouver) were prospectively examined for suspected sleep disordered breathing.
Methods: All subjects underwent a history and physical examination with measurements of anthropometric parameters and craniofacial structure including neck circumference, thyromental distance, thyromental angle, and Mallampati oropharyngeal score. OSA was defined as an apnoea-hypopnoea index (AHI) of ⩾5/hour on full overnight polysomnography.
Results: Discriminant function analysis indicated that the Mallampati score (F = 0.70), thyromental angle (F = 0.60), neck circumference (F = 0.54), body mass index (F = 0.53), and age (F = 0.53) were the best predictors of OSA. After controlling for ethnicity, body mass index and neck circumference, patients with OSA were older, had larger thyromental angles, and higher Mallampati scores than non-apnoeic subjects. These variables remained significantly different between OSA patients and controls across a range of cut-off values of AHI from 5 to 30/hour.
Conclusions: A crowded posterior oropharynx and a steep thyromental plane predict OSA across two different ethnic groups and varying degrees of obesity.
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.
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.
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.
Background and Aim:
Obstructive sleep apnea (OSA) syndrome is predisposed to the development of upper airway obstruction during sleep, and it poses considerable problem for anesthetic management. Difficult intubation (DI) is an important problem for management of anesthesia. In this clinical research, we aim to investigate the relationship between DI and prediction criteria of DI in cases with OSA.
Materials and Methods:
We studied 40 [OSA (Group O, n = 20) and non-OSA, (Group C, n = 20)] ASA I-II, adult patients scheduled tonsillectomy under general anesthesia. Same anesthetic protocol was used in two groups. Intubation difficulties were assessed by Mallampati grading, Wilson sum score, Laryngoscopic grading (Cormack and Lehane), a line joining the angle of the mouth and tragus of the ear with the horizontal, sternomental distance, and tyromental distance. Demographic properties, time-dependent hemodynamic variables, doses of reversal agent, anesthesia and operation times, and recovery parameters were recorded.
Significant difference was detected between groups in terms of BMI, Mallampati grading, Wilson weight scores, Laryngoscopic grading, sternomental distance, tyromental distance, doses of reversal agent, and recovery parameters.
OSA patient's DI ratio is higher than that of non-OSA patients. BMI Mallampati grading, Wilson weight scores, Laryngoscopic grading, sternomental distance, and tyromental distance evaluation might be predictors for DI in patients with OSA.
Difficult intubation; obstructive sleep apnea; predictive factors
The aim of the study was to assess and compare laryngoscopic view of Truview evo2 laryngoscope with that of Macintosh laryngoscope in patients with one or more predictors of difficult intubation (PDI). Moreover ease of intubation with Truview evo2 in terms of absolute time requirement was also aimed at. Patients for elective surgery requiring endotracheal intubation were initially assessed for three PDI parameters – modified Mallampati test, thyro-mental distance & Atlanto-occipital (AO) joint extension. Patients with cumulative PDI scores of 2 to 5 (in a scale of 0 to 8) were evaluated for Cormack & Lehane (CL) grading by Macintosh blade after standard induction. Cases with CL grade of two or more were further evaluated by Truview evo2 laryngoscope and corresponding CL grades were assigned. Intubation attempted under Truview evo2 vision and time required for each successful tracheal intubation (i.e. tracheal intubation completed within one minute) was noted. Total fifty cases were studied. The CL grades assigned by Macintosh blade correlated well with the cumulative PDI scores assigned preoperatively, confirming there predictability. Truview evo2 improved laryngeal view in 92 % cases by one or more CL grade. Intubation with Truview evo2 was possible in 88% cases within stipulated time of one minute and mean time of 28.6 seconds with SD of 11.23 was reasonably quick. No significant complication like oro- pharyngeal trauma or extreme pressor response to laryngoscopy was noticed. To conclude, Truview evo2 proved to be a better tool than conventional laryngoscope in anticipated difficult situations.
Difficult airway; Truview laryngoscope; Macintosh laryngoscope
The Truview EVO2™ laryngoscope is a recently introduced device with a unique blade that provides a magnified laryngeal view at 42° anterior reflected view. It facilitates visualization of the glottis without alignment of oral, pharyngeal, and tracheal axes. We compared the view obtained at laryngoscopy, intubating conditions and hemodynamic parameters of Truview with Macintosh blade.
Materials and Methods:
In prospective, randomized and controlled manner, 200 patients of ASA I and II of either sex (20–50 years), presenting for surgery requiring tracheal intubation, were assigned to undergo intubation using a Truview or Macintosh laryngoscope. Visualization of the vocal cord, ease of intubation, time taken for intubation, number of attempts, and hemodynamic parameters were evaluated.
Truview provided better results for the laryngeal view using Cormack and Lehane grading, particularly in patients with higher airway Mallampati grading (P < 0.05). The time taken for intubation (33.06±5.6 vs. 23.11±57 seconds) was more with Truview than with Macintosh blade (P < 0.01). The Percentage of Glottic Opening (POGO) score was significantly higher (97.26±8) in Truview as that observed with Macintosh blade (83.70±21.5). Hemodynamic parameters increased after tracheal intubation from pre-intubation value (P < 0.05) in both the groups, but they were comparable amongst the groups. No postoperative adverse events were noted.
Tracheal intubation using Truview blade provided consistently improved laryngeal view as compared to Macintosh blade without the need to align the oral, pharyngeal and tracheal axes, with equal attempts for successful intubation and similar changes in hemodynamics. However, the time taken for intubation was more with Truview.
Airway; difficult intubation; equipment; Macintosh laryngoscope; tracheal intubation; Truview EVO2 laryngoscope
Aim: To assess whether an airway assessment score based on the LEMON method is able to predict difficulty at intubation in the emergency department.
Methods: Patients requiring endotracheal intubation in the resuscitation room of a UK teaching hospital between June 2002 and September 2003 were assessed on criteria based on the LEMON method. At laryngoscopy, the Cormack and Lehane grade was recorded. An airway assessment score was devised and assessed.
Results: 156 patients were intubated during the study period. There were 114 Cormack and Lehane grade 1 intubations, 29 grade 2 intubations, 11 grade 3 intubations, and 2 grade 4 intubations. Patients with large incisors (p<0.001), a reduced inter-incisor distance (p<0.05), or a reduced thyroid to floor of mouth distance (p<0.05) were all more likely to have a poor laryngoscopic view (grade 2, 3, or 4). Patients with a high airway assessment score were more likely to have a poor laryngoscopic view compared with those patients with a low airway assessment score (p<0.05).
Conclusions: An airway assessment score based on criteria of the LEMON method is able to successfully stratify the risk of intubation difficulty in the emergency department. Patients with a poor laryngoscopic view (grades 2, 3, or 4) were more likely to have large incisors, a reduced inter-incisor distance, and a reduced thyroid to floor of mouth distance. They were also more likely to have a higher airway assessment score than those patients with a good laryngoscopic view.
In trauma patients intubated in a physician-led pre-hospital trauma service we prospectively examined the rate of misplaced tracheal tubes, the presence and nature of gross airway contamination, and the value of ‘quick look’ airway assessment to identify patients with subsequent difficult laryngoscopy.
Patients requiring pre-hospital intubation in a 16 month period were included. Intubation success rate, misplaced tracheal tube rate, Cormack and Lehane grade, and the presence and nature of gross airway contamination were recorded at laryngoscopy. Tube placement was verified with carbon dioxide detection and chest x-ray. After visual assessment physicians stated whether laryngoscopy was expected to be a straightforward or ‘difficult’. The assessment was compared to subsequent laryngoscopy grade.
400 patients had attempted intubation and 399 were successfully intubated. 42 were in cardiac arrest and intubated without drugs. There were no oesophageal or misplaced tracheal tubes. Gross airway contamination was reported in 177 of 400 patients (44%), of which ¾ was from the upper airway. Unconscious patients had higher contamination rates (57%) than conscious patients (34%) (p ≤ 0.0001). As a test of difficult intubation, the ‘quick look’ generated sensitivity 0.597 and specificity 0.763 (PPV and NPV were 0.336 and 0.904 respectively).
This study suggests that when physicians perform pre-hospital anaesthesia they have high intubation success rates and the use of ETCO2 monitoring reduces or eliminates undetected misplaced tracheal tubes. We found high rates of airway contamination; mostly blood from the upper airway. The ‘quick look’ airway assessment had some utility but is unreliable in isolation.
Tracheal intubation; Airway; Pre-hospital; Anaesthesia
A 35-year-old male with pan-anterior urethral stricture was scheduled to undergo perineal urethrostomy. He was a known case of Kindler's syndrome since infancy. He was having a history of blister formation, extensive poikiloderma and progressive cutaneous atrophy since childhood. He had a tendency of trauma-induced blisters with clear or hemorrhagic contents that healed with scarring. The fingers were sclerodermiform with dystrophic nails and inability to completely clench the fist. Airway examination revealed thyromental distance of 7 cm with limited neck extension, limited mouth opening and mallampatti class III with a fixed large tongue. He was reported as grade IV Cormack and Lehane laryngoscopic on previous anesthesia exposure. We described the anesthetic management of such case on guidelines for epidermolysis bullosa. In the operating room, an 18-G cannula was secured in the right upper limb using Coban™ Wrap. The T-piece of the cannula was than inserted into the slit and the tape was wrapped around the extremity. The ECG electrodes were placed on the limbs and fixed with Coban™. Noninvasive blood pressure cuff was applied over the wrap after wrapping the arm with Webril® cotton. Oral fiberoptic tracheal intubation was done after lubricating the laryngoscope generously with a water-based lubricant with 7-mm endotracheal tube. Surgery proceeded without any complication. After reversing the residual neuromuscular block, trachea was extubated once the patient became awake. He was kept in the postanesthesia care unit for 2 hours and then shifted to urology ward.
Difficult airway; epidermolysis bullosa; Kindler's syndrome
Unanticipated difficult tracheal intubation remains a primary concern of anaesthesiologists and upper lip bite test (ULBT) is one of the assessments used in predicting difficult intubation. In this study, we aimed to check the utility of lateral neck X-ray measurements in improving the diagnostic value of the ULBT.
In a prospective study conducted from January 2007 until December 2010, we recorded personal and demographic data of 4500 patients who entered the study and subjected them to standard lateral neck radiography. Before the induction of anaesthesia, clinical examination and ULBT results were recorded and during induction of anaesthesia laryngoscopic grading was evaluated and recorded in questionnaires. All the compiled data were analysed by SPSS 14.0 (SPSS Inc., Chicago, IL, USA) software. Diagnostic value for each test was calculated and compared.
Negative predictive values (NPVs) were high in all tests. ULBT had the highest specificity and NPV compared with the other tests. The positive predictive value for all the tests had been low, but marginally high in the ULBT.
Although all the tests used had relatively acceptable predictive values, combination of tests appeared to be more predictive. Highest sensitivities were observed with ULBT, mandibulohyoid distance and thyromental distance respectively. Use of radiological parameters may not be suitable as screening tools, but may help in anticipating and preparing for a difficult scenario.
Airway assessment; difficult intubation; lateral neck radiography; predictive tests; upper lip bite test
Although the difficulty of tracheal intubation in the lateral position has not been systematically evaluated, airway loss during surgery in a laterally positioned patient may have hazardous consequences. We explored whether the intubating laryngeal mask airway (ILMA) facilitates tracheal intubation in patients with normal airway anatomy, i.e., Mallampati grade ≤ 3 and thyromental distance ≥ 5 cm, positioned in the lateral position. And we evaluated whether this technique can be used as a rescue when the airway is lost mid-case in laterally positioned patients with respect to success rate and intubation time. Anesthesia was induced with propofol, fentanyl, and vecuronium in 50 patients undergoing spine surgery for lumbar disk herniation (Lateral) and 50 undergoing other surgical procedures (Supine). Patients having disk surgery (Lateral) were positioned on their right or left sides before induction of general anesthesia, and intubation was performed in that position. Patients in control group (Supine) were anesthetized in supine position, and intubation was performed in that position. Intubation was performed blindly via an ILMA in both groups. The time required for intubation and number and types of adjusting maneuvers employed were recorded. Data were compared by Mann-Whitney U, Fisher’s exact, chi-square, or unpaired t-tests, as appropriate. Data presented as mean (SD). Demographic and airway measures were similar in the two groups, except for mouth opening which was slightly wider in patients in the lateral position: 5.1 (0.9) vs. 4.6 (0.7) cm. The time required for intubation was similar in each group (≈25 s), as was intubation success (96%). We conclude that blind intubation via an ILMA offers a frequent success rate and a clinically acceptable intubation time (< one min) even in the lateral position.
Blind intubation via the intubating laryngeal mask airway (ILMA) offers a high success rate and a clinically acceptable intubation time even in patients in the lateral position.
Equipment: intubating laryngeal mask airway; Position: lateral: Intubation (Tracheal): technique
The Truview EVO2 blade facilitates the view of vocal cords by indirect laryngoscopy and does not require the proper alignment of the oral, pharyngeal and tracheal axes as with the Macintosh blade.
In a crossover fashion, we prospectively compared the view obtained at laryngoscopy with Truview EVO2 and the Macintosh blade in 110 adult patients of either sex between the age of 18 and 60 years, who were scheduled to undergo general anesthesia with endotracheal intubation. The patients were intubated with the second laryngoscope. The preoperative airway variables, laryngoscopic view, difficulty of intubation scale (IDS) score, duration of intubation, and degree of difficulty percentage of glottic opening (POGO score) of use with each laryngoscope were compared.
The IDS score was low and comparable between the two laryngoscopes. The laryngeal view was easy; Modified Cormack Lehane (MCL) grade 2a or less in 98.14% of the cases with the Truview laryngoscope compared to 78.7% of the cases with the Macintosh laryngoscope. Nineteen patients of MCL grade 3, one patient of grade 2b, and seven patients of grade 2a view with the Macintosh laryngoscope had MCL grade 1 view with the Truview laryngoscope. The duration of intubation was comparable between Truview and Macintosh laryngoscopes (12.1±3.8 s vs. 10.9±2.1 s).
Truview laryngoscope performed comparably to Macintosh laryngoscope in patients with normal airway; however, the Truview laryngoscope may be a better option in difficult airway situations when the Macintosh blade fails to show the glottic opening.
Difficult airway; intubation difficulty scale score; laryngoscopic view; Macintosh laryngoscope; Truview EVO2
The primary objective of this study was to compare the effect of ventilation using the ProSeal™ laryngeal mask airway (PLMA) with facemask and oropharyngeal airway (FM), prior to laryngoscopy, on arterial oxygenation in morbidly obese patients undergoing bariatric surgery.
Forty morbidly obese patients were randomly recruited to either PLMA or FM. After pre-oxygenation (FiO2 1.0) in the ramp position with continuous positive airway pressure of 10 cm H2O for 5 min, anaesthesia was induced. Following loss of jaw thrust oropharyngeal airway, the FM and PLMA were inserted. On achieving paralysis, volume control ventilation with PEEP (5 cm H2O) was initiated. The difficulty in mask ventilation (DMV) in FM, number of attempts at PLMA and laryngoscopy were graded (Cormack and Lehane) in all patients. Time from onset of laryngoscopy to endotracheal tube confirmation was recorded. Hypoxia was defined as mild (SpO2 ≤95%), moderate (SpO2 ≤90%) and severe (SpO2 ≤85%).
Significant rise in pO2 was observed within both groups (P=0.001), and this was significantly higher in the PLMA (P=0.0001) when compared between the groups. SpO2 ≥ 90% (P=0.018) was seen in 19/20 (95%) patients in PLMA and 13/20 (65%) in FM at confirmation of tracheal tube. A strong association was found between DMV and Cormack Lehane in the FM group and with number of attempts in the PLMA group. No adverse events were observed.
ProSeal™ laryngeal mask airway as conduit prior to laryngoscopy in morbidly obese patients seems effective in increasing oxygen reserves, and can be suggested as a routine airway management technique when managing the airway in the morbidly obese.
Bariatric; morbidly obese; oxygenation; ProSeal™
Difficult airway continued to be a major cause of anesthesia-related morbidity and mortality. Successful airway management depends on direct laryngoscopy and tracheal intubation. Difficult laryngoscopy is a resultant of incomplete structural arrangements during the process of head positioning. Through clinical history, examination of the patients along with craniofacial indices alerts the anesthetist for difficult laryngoscopy. But it does not predict all causes of difficult laryngoscopy during pre-anesthetic evaluation. The maxillo-pharyngeal angle, an upper airway anatomical balance, was proposed for better understanding the pathophysiology of difficult laryngoscopy. In our study we have assess difficult laryngoscopy by electronically measuring maxillo-pharyngeal angles on a lateral cervical radiograph. This angle is normally greater than 100°. Less than 90° angle suggests either impossible or difficult direct laryngoscopy when all known craniofacial indices were within the normal range. Cervical radiographic assessment is a simple, economical, and non-invasive predictive method for difficult laryngoscopy. It should be used routinely along with other indices as pre-anesthetic airway assessment criteria to predict the difficult laryngoscopy.
Difficulties with airway management continue to be a major cause of anesthesia-related morbidity, mortality, and litigation. Pre-operative assessment of difficult laryngoscopy by the simple and non-invasive radiological method can help to prevent them.
To assess the difficult laryngoscopy pre operatively by a simple and non invasive radiological method by electronically measuring maxillo-pharyngeal angle on a lateral cervical radiograph and it’s correlation with Cormack and Lehane grading.
Settings and Design:
This is a controlled, nonrandomized, prospective, cohort observation study.
Patients and Methods:
The 157 adult consented patients of ASA grade I to III of either sex, scheduled for elective surgery under general anesthesia with endo-tracheal intubation, were studied. The patients with identified difficult airway indices were excluded from the study. The maxillo-pharyngeal angle was electronically measured on a lateral cervical radiograph and was correlated with ease or difficulty of laryngoscopy under general anesthesia. Their degree of laryngeal exposure according to Cormack and Lehane classification grade was also noted.
Statistical Analysis used:
We performed univariate analyses to evaluate the association between the covariates and direct laryngoscopy.
In 148 patients (94.28%), the maxillo-pharyngeal angle was more than 100°, in 7 patients (4.45%) it was less than 90°, and in 2 patients (1.27%) the M-P angle was less than 85° with normal craniofacial indices. When the MP angle was less than 90°, the direct laryngoscopy was difficult which could be compared with to Cormack and Lehane classification grade III and IV.
Lateral cervical radiographic assessment should be used as pre-anesthetic airway assessment criteria to predict the difficult laryngoscopy as it is a simple, safe and non-invasive method.
Maxillo-pharyngeal angle; laryngoscopy; cervical radiograph; electronic measurement of angle; Cormack and Lehane grade
The Truview EVO2(C) laryngoscope (TL) is a recently introduced optical device designed to provide an unmagnified anterior image of the glottic opening and allow indirect laryngoscopy.
This study is designed to determine whether the TL is a better alternative to the Macintosh laryngoscope (ML) for routine endotracheal intubations in patients with usual airway characteristics.
We compared the Truview EVO2(C) and MLs in 140 elective surgical patients requiring general anaesthesia and intubation in a prospective crossover fashion. The two blades were compared in terms of Cormack and Lehane grades, time required for intubation, anaesthetists’ assessment of ease of intubation, intubation difficulty score, attempts at intubation, success rate, soft tissue damage and arterial oxygen saturation during laryngoscopy. The Student t test and Chi-square test were used to determine the statistical significance of parametric data and categorical data, respectively.
The Truview EVO2(C) blade provided a better laryngoscopic view than the Macintosh blade as suggested by improved Cormack and Lehane grades (in 48 patients), but required a longer time for intubation than the Macintosh blade (34.1 vs. 22.4 s), i.e., an improved view at the cost of longer mean intubation time. In spite of lower intubation difficulty scores, Truview EVO2(C) was considered as difficult to use on subjective assessment by the anaesthesiologist when compared with Macintosh. There was no difference observed between the two groups in attempts at intubation, success rate, soft tissue damage and arterial oxygen saturation during laryngoscopy.
We opine that although Truview provides a better laryngoscopic view than Macintosh in difficult cases, it does not have an extra benefit over Macintosh otherwise, further indicating the need for more experience with the use of a Truview laryngoscope.
Airway; difficult intubation; equipment; Macintosh laryngoscope; tracheal intubation Truview EVO2(C) laryngoscope
Head extension and excessive laryngoscope blade levering motion
(LBLM) are undesirable during airway management of trauma patients. We
hypothesized that laryngoscopy with a modified blade facilitating glottic
exposure by balloon inflation would reduce head extension and LBLM.
Patients and methods:
Seventeen elective surgery patients were enrolled. Patients lay
supine with their heads flat on a rigid board and had a rigid collar around
their necks. Laryngoscopy was performed with the modified blade and a standard
curved blade. Head extension and LBLM angles were determined upon maximal
glottic exposure and compared used paired t-tests. Laryngoscopic view
grade and oxygen saturation were also determined.
Balloon laryngoscopy resulted in less head extension and LBLM
(P <0.001). Laryngoscopic view was approximately identical with
both blades, and oxygen saturation was always above 97%.
Balloon laryngoscopy reduces head extension and LBLM under
simulated cervical spine precautions.
balloon laryngoscopy; blade; extension; head; leverage; spine
Tracheal intubation in the prone position has previously been reported only as a necessity in a very few emergency situations. It emerged at our clinic as a routine after invention of a test aimed at pinpointing a painful motion segment in patients with chronic low back pain who were candidates for lumbar fusion operation.
Material and methods.
During a 6-year period 247 consecutive patients were treated at our clinic, 91 men and 156 women, mean age 42.8 years, range 25.3–62.8. Classification of the pharyngeal structures according to Mallampati et al. was done the day before surgery, and grading of visualization of the glottis as described by Cormack and Lehane was done during intubation, with the aim of revealing factors of importance for the possibility of performing tracheal intubation in the prone position.
The large majority of patients classified preoperatively as Mallampati class 1 had Cormack and Lehane grade 1 at laryngoscopy, although some patients had grades 2, 3, and 4. Most problems with intubation in the prone position were anticipated among those classified preoperatively as Mallampati class 3, but tracheal intubation in the prone position was still possible in 21 of the 23 patients in this group. In all, tracheal intubation in the prone position was successful in 244 of the 247 patients (98.8%).
Routine tracheal intubation in the prone position can be performed effectively by experienced anaesthesiologists, but this requires continuous training and good support from the anaesthesiology staff.
Anaesthesia; endotracheal intubation; laryngoscopy; pharyngeal anatomy; prone position
Literature suggests glottic view is better with straight blades while tracheal intubation is easier with curved blades.
To compare glottic view and ease of intubation with Macintosh, Miller, McCoy blades and the Trueview® laryngoscope.
Settings and Design:
This prospective randomised study was undertaken in operation theatres of a 550 bedded tertiary referral cancer centre after approval from the Institutional Review Board.
We compared the Macintosh, Miller, McCoy blades and the Trueview® laryngoscope for glottic visualisation and ease of tracheal intubation; in 120 patients undergoing elective cancer surgery; randomly divided into four groups. After induction of anaesthesia laryngoscopy was performed and trachea intubated. We recorded: Visualisation of glottis (Cormack Lehane grade), ease of intubation, number of attempts; need to change the blade and need for external laryngeal manipulation.
Demographic data, Mallampati classification were compared using the Chi-square test. A P<0.05 was considered significant.
Grade 1 view was obtained most often (87% patients) with Trueview® laryngoscope. Intubation was easier (Grade 1) with Trueview® and McCoy blades (93% each). Seven patients needed two attempts; one patient in Miller group needed three attempts. No patient in McCoy and Trueview® Groups required external laryngeal manipulation.
We found that in patients with normal airway glottis was best visualised with Miller blade and Trueview® laryngoscope however, the trachea was more easily intubated with McCoy and Macintosh blades and Trueview® laryngoscope.
Cormack lehane grade; external laryngeal manipulation; intubation; laryngoscopy