Difficult mask ventilation in obese patients: analysis of predictive factors

BACKGROUND

This study aimed to determine the accuracy of commonly used preoperative difficult airway indices as predictors of difficult mask ventilation (DMV) in obese patients (BMI >30 kg/m2).

METHODS

In 309 consecutive obese patients undergoing general surgery, the modified Mallampati test, patient's Height/Thyromental distance ratio, Inter-Incisor Distance, Protruding Mandible (PM), history of Obstructive Sleep Apnea and Neck Circumference (NC) were recorded preoperatively. DMV was defined as Grade 3 mask ventilation (MV) by the Han's scale (MV inadequate, unstable or requiring two practitioners). Data are shown as means±SD or number and proportions. Independent DMV predictors were identified by multivariate analysis. The discriminating capacity of the model (ROC curve area) and adjusted weights for the risk factors (odds ratios) were also determined.

RESULTS

BMI averaged 42.5±8.3 kg/m2. DMV was reported in 27 out of 309 patients (8.8%; 95%CI 5.6-11.9%). The multivariate analysis retained NC (OR 1.17; P<0.0001), limited PM (1.99; P=0.046) and Mallampati test (OR 2.12; P=0.009) as risk predictors for DMV. Male gender was also included in the final model (OR 1.87; P=0.06) as biologically important variable albeit the borderline statistical significance. The model yielded a good discriminating capacity (ROC curve 0.85). The four parameters were used to create an unweighted prediction score (ROC curve 0.84) with >2 associated factors as the best discriminating point for DMV.

CONCLUSION

Obese patients show increased incidence of DMV with respect to the undifferentiated surgical population. Limited PM, Mallampati test and NC are important DMV predictors.

Comparison of success rates between two video laryngoscope systems used in a prehospital clinical trial

OBJECTIVES

The primary aims of this study were to compare paramedic success rates and complications of two different video laryngoscopes in a prehospital clinical study.

METHODS

This study was a multi-agency, prospective, non-randomized, cross over clinical trial involving paramedics from four different EMS agencies. Following completion of training sessions, six Storz CMAC™ video laryngoscopes and six King Vision™ (KV) video laryngoscopes were divided between agencies and placed into service for 6 months. Paramedics were instructed to use the video laryngoscope for all patients estimated to be ≥ 18 years old who required advanced airway management per standard operating procedure. After 6 months, the devices were crossed over for the final 6 months of the study period. Data collection was completed using a telephone data collection system with a member of the research team (available 24/7). First attempt success, overall success, and success by attempt, were compared between treatment groups using exact logistic regression adjusted for call type and user experience.

RESULTS

Over a 12-month period, 107 patients (66 CMAC, 41 KV) were treated with a study device. The CMAC had a significantly higher likelihood of first attempt success (OR = 1.85; 95% CI 0.74, 4.62; p = 0.188), overall success (OR = 7.37; 95% CI 1.73, 11.1; p = 0.002), and success by attempt (OR = 3.38; 95% CI 1.67, 6.8; p = 0.007) compared to KV. Providers reverted to direct laryngoscopy in 80% (27/34) of the video laryngoscope failure cases, with the remaining patients having their airways successfully managed with a supraglottic airway in 3 cases and bag-valve mask in 4 cases. The provider-reported complications were similar and none were statistically different between treatment groups. Complication rates were not statistically different between devices.

CONCLUSION

The CMAC had a higher likelihood of successful intubation compared to the King Vision. Complication rates were not statistically different between groups. Video laryngoscope placement success rates were not higher than our historical direct laryngoscopy success rates.

The Cric-Key™ and Cric-Knife™: a combined tube-introducer and scalpel-hook open cricothyrotomy system

The author describes a cricothyrotomy system that consists of two devices that, packaged together, are labeled the Control-Cric™ system. The Cric-Key™ was invented to verify tracheal location during surgical airway procedures?without the need for visualization, aspiration of air, or reliance on clinicians? fine motor skills. The Cric-Knife™ combines a scalpel with an overlying sliding hook to facilitate a smooth transition from membrane incision to hook insertion and tracheal control. In a recent test versus a traditional open technique, this system had a higher success rate and was faster to implement.

A comparative study of the efficacy of Pediatric Airtraq® with conventional laryngoscope in children

BACKGROUND

Management of pediatric airway may pose a challenge to anesthesiologists. Many modifications in maneuvers and equipments have been made overtime to overcome the problem. Pediatric optical laryngoscope (Airtraq®) is one of the newer equipments for managing simple and difficult pediatric airway. Here we have evaluated the comparative efficacy of pediatric Airtraq® optical laryngoscope with conventional laryngoscope in children scheduled for routine surgeries.

METHODS

After written informed consent from the parents/guardian of the children, they were allocated into two groups of 17 patients each using the pediatric Airtraq® in one and a conventional laryngoscope in the other. Airtraq® intubation patients were those in which pediatric Airtraq® was used to intubate whereas the patients who were intubated with conventional laryngoscope were labelled as conventional intubation group. The primary outcome measure was time needed for successful intubation whereas secondary outcome measures were number of attempts to intubate, POGO (percentage of glottic opening) scoring and complications like airway trauma and esophageal intubation.

RESULTS

It took significantly shorter time to intubate in Airtraq® intubation group of patients as compared to Conventional intubation group of patients (P<0.05). Similarly the POGO scoring was significantly better in Airtraq intubation compared to Conventional intubation (P <0.001). Number of attempts to intubate and complications like airway trauma and esophageal intubation using Airtraq® was less frequent compared to conventional laryngoscopy but the difference was statistically insignificant.

CONCLUSION

Pediatric Airtraq® provides better intubating conditions in children compared to conventional laryngoscope with less frequent complications.

Successful management of trachea stenosis with massive substernal goiter via thacheobronchial stent

A case of 65 year-old Chinese male patient with severe tracheal stenosis due to a massive substernal goiter, is presented. MRI and CT scan revealed that the massive substernal goiter was 9.3 × 6.1 × 4.7 cm in size, displacing the trachea and adjacent large vessels to the patient's right contributing to severe intrathoracic trachea compression up to 6 cm in length and the narrowest caliber of the trachea only 3.0 mm in diameter. To the best of our knowledge, optimal airway management for the massive substernal goiter resection was considered to be temporary tracheobronchial stent placement pre-operation.

Supraglottic airway devices versus tracheal intubation for airway management during general anaesthesia in obese patients

BACKGROUND

The number of obese patients requiring general anaesthesia is likely to increase in coming years, and obese patients pose considerable challenges to the anaesthetic team. Tracheal intubation may be more difficult and risk of aspiration of gastric contents into the lungs is increased in obese patients. Supraglottic airway devices (SADs) offer an alternative airway to traditional tracheal intubation with potential benefits, including ease of fit and less airway disturbance. Although SADs are now widely used, clinical concerns remain that their use for airway management in obese patients may increase the risk of serious complications.

OBJECTIVES

We wished to examine whether supraglottic airway devices can be used as a safe and effective alternative to tracheal intubation in securing the airway during general anaesthesia in obese patients (with a body mass index (BMI) > 30 kg/m(2)).

SEARCH METHODS

We searched for eligible trials in the following databases: Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 8, 2012), MEDLINE via Ovid (from 1985 to 9 September 2012) and EMBASE via Ovid (from 1985 to 9 September 2012). The Cochrane highly sensitive filter for randomized controlled trials was applied in MEDLINE and EMBASE. We also searched trial registers such as www.clinicaltrials.gov and the Current Controlled Clinical Trials Website (http://www.controlled-trials.com/) for ongoing trials. The start date of these searches was limited to 1985, shortly before the first SAD was introduced, in 1988. We undertook forward and backward citation tracing for key review articles and eligible articles identified through the electronic resources.

SELECTION CRITERIA

We considered all randomized controlled trials of participants aged 16 years and older with a BMI > 30 kg/m(2) undergoing general anaesthesia. We compared the use of any model of SAD with the use of tracheal tubes (TTs) of any design.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by The Cochrane Collaboration. Two review authors independently assessed trial quality and extracted data, including information on adverse events. We contacted study authors for additional information. If sufficient data were available, results were presented as pooled risk ratios (RRs) with 95% confidence intervals (CIs) based on random-effects models (inverse variance method). We employed the Chi(2) test and calculated the I(2) statistic to investigate study heterogeneity.

MAIN RESULTS

We identified two eligible studies, both comparing the use of one model of SAD, the ProSeal laryngeal mask airway (PLMA) with a TT, with a total study population of 232. One study population underwent laparoscopic surgery. The included studies were generally of high quality, but there was an unavoidable high risk of bias in the main airway variables, such as change of device or laryngospasm, as the intubator could not be blinded. Many outcomes included data from one study only.A total of 5/118 (4.2%) participants randomly assigned to PLMA across both studies were changed to TT insertion because of failed or unsatisfactory placement of the device. Postoperative episodes of hypoxaemia (oxygen saturation < 92% whilst breathing air) were less common in the PLMA groups (RR 0.27, 95% CI 0.10 to 0.72). We found a significant postoperative difference in mean oxygen saturation, with saturation 2.54% higher in the PLMA group (95% CI 1.09% to 4.00%). This analysis showed high levels of heterogeneity between results (I(2) = 71%). The leak fraction was significantly higher in the PLMA group, with the largest difference seen during abdominal insufflation－a 6.4% increase in the PLMA group (95% CI 3.07% to 9.73%).No cases of pulmonary aspiration of gastric contents, mortality or serious respiratory complications were reported in either study. We are therefore unable to present effect estimates for these outcomes.In all, 2/118 participants with a PLMA suffered laryngospam or bronchospasm compared with 4/114 participants with a TT. The pooled estimate shows a non-significant reduction in laryngospasm in the PLMA group (RR 0.48, 95% CI 0.09 to 2.59).Postoperative coughing was less common in the PLMA group (RR 0.10, 95% CI 0.03 to 0.31), and there was no significant difference in the risk of sore throat or dysphonia (RR 0.25, 95% CI 0.03 to 2.13). On average, PLMA placement took 5.9 seconds longer than TT placement (95% CI 3 seconds to 8.8 seconds). There was no significant difference in the proportion of successful first placements of a device, with 33/35 (94.2%) first-time successes in the PLMA group and 32/35 (91.4%) in the TT group.

AUTHORS' CONCLUSIONS

We have inadequate information to draw conclusions about safety, and we can only comment on one design of SAD (the PLMA) in obese patients. We conclude that during routine and laparoscopic surgery, PLMAs may take a few seconds longer to insert, but this is unlikely to be a matter of clinical importance. A failure rate of 3% to 5% can be anticipated in obese patients. However, once fitted, PLMAs provide at least as good oxygenation, with the caveat that the leak fraction may increase, although in the included studies, this did not affect ventilation. We found significant improvement in oxygenation during and after surgery, indicating better pulmonary performance of the PLMA, and reduced postoperative coughing, suggesting better recovery for patients.

An overview on the use of the laryngeal mask airway amongst anaesthesia practitioners in a developing country

BACKGROUND

The aim of this study is to provide an overview on the use of the Laryngeal Mask Airway (LMA) amongst anaesthesia practitioners in Nigeria

MATERIALS AND METHODS

This is a multicentre questionnaire based study involving eight tertiary health care institutions in Nigeria. The questionnaires were administered to anaesthetists. They were standardised open- and close-ended questions which were completed in person. The questionnaire was subdivided into a set of questions which include: status of the anaesthetist; the routine use of LMA in general anaesthesia and as a device for airway management in difficult airway. Statistical analyses were done by simple percentages.

RESULTS

The numbers of respondents were seventy; 38 were junior residents, 20 were senior residents and 12 were consultants. Sixty (85.7%) respondent had personally used LMA, while 10 had never used it and they were all junior residents. Classic LMA was most commonly used (88%), followed by intubating LMA (7.5%), and proseal LMA (4.5%). Most of the respondents (67.1%) have used LMA in difficult airway management while 10% of respondents had used it in airway management during cardiopulmonary resuscitation (CPR). The reason for not using LMA routinely for general anaesthesia was due to unavailability in 15.7% of respondents, inexperience in 8.6% and habitual in 30%.

CONCLUSION

Airway management is a vital discipline in the specialty of anaesthesia. The use of LMA as an airway device in the practice of anaesthesia in our setting is inadequate. Training, re-training and continuous medical education of anaesthetists' very necessary to improve our practice.

[The application of nasopharyngeal airway in nurosurgery patients during anesthesia recovery]

OBJECTIVE

To evaluate safety and effectiveness of nasopharyngeal airway used for neurosurgery patients during the anesthesia recovery period.

METHODS

A total of 60 patients (ASAI-II), aged between 25 to 67 years old, who were scheduled to undergo elective neurosurgery operation under general anesthesia, were randomly divided into the oropharyngeal airway group (group O) and the nasopharyngeal airway group (group N), with 30 cases in each group. After respiratory recovery was satisfactory at the end of operation, endotracheal tube was extubated under deep anesthesia. Afterwards, oropharyngeal airway was intubated in group O, and nasopharyngeal airway was intubated in group N. BP and HR before induction (T0), before airway intubation (T1), at 1 min (T2) and 5 min (T3) after airway intubation were recorded. Meanwhile, one-time success rate of airway intubation, the airway retention time, the times of airway regulation due to location change and the change of respiration and circulation in each groups during airway retention period were recorded. In addition, adverse reactions during airway retention period and tolerance scores of patients in both groups were recorded.

RESULTS

BP and HR in group N at T1 and T2 increased significantly compared with T0 (P < 0.05), Compared with T1, BP and HR increased significantly at T2 in group N (P < 0.05). Compared with T1 and T2, the same index reduced significantly at T3 (P < 0.05). BP and HR in group N were significantly higher than those in group O at T2 (P < 0.05). Airway retention time in group N was significantly longer than that in group O [(137.4 +/- 18.32) min vs. (64.2 +/- 8.25) min, P < 0.053; the times of airway location regulation in group N was less than that in group O (0.34 +/- 0.21 vs. 2.80 +/- 0.54) (P < 0.05). During airway retention period the incidence of BP and HR exceeding the base value by 15% in group O was higher than that in group N (80.0% vs. 46.7%)(P < 0.01), and the incidence of SPO2 less than 95% in group O was higher than that in group N (26.7% vs. 6.7%) (P < 0.05). The incidence of nausea, upper airway obstruction and restlessness in group O was significantly higher than that in group N (P < 0.05). Moreover, airway tolerance score of patients in group N was significantly better than that in group O (P < 0.05).

CONCLUSION

Nasopharyngeal airway could better maintain unobstructed upper airway in neurosurgery patients during the anesthesia recovery period with advantages such as small circulatory effect, good tolerance and fewer complications.

Airtraq optical laryngoscope: advantages and disadvantages

Difficult or unsuccesful tracheal intubation is one of the important causes for morbidity and mortality in susceptible patients. Almost 30% of the anesthesia-related deaths are induced by the complications of difficult airway management and more than 85% of all respiratory related complications cause brain injury or death. Nowadays, due to the advances in technology, new videolaryngoscopic devices became available. Airtraq is a novel single-use laryngoscope which provides glottis display without any deviation in the normal position of the oral, pharyngeal or the tracheal axes. With the help of the display lens glottis and the surrounding structures are visualised and under direct view of its tip the tracheal tube is introduced between the vocal cords. In patients having restricted neck motion or limited mouth opening (provided that it is greater than 3 cm) Airtraq offers the advantage of a better display. Moreover the video image can be transfered to an external monitor thus an experienced specialist can provide assistance and an educational course can be conducted simultaneously. On the other hand the Airtraq videolaryngoscopic devices possess certain disadvantages including the need of experience and the time demand for the operator to learn how to use them properly, the rapid deterioration of their display in the presence of a swelling or a secretion and the fact that they are rather complicated and expensive devices. The Airtraq device has already documented benefits in the management of difficult airways, however serial utilization obviously necessitates experience.

Laryngeal mask airway insertion in adults: comparison between fully deflated and partially inflated technique

PURPOSE

The laryngeal mask airway (LMA) is a supraglottic airway device designed to seal around the laryngeal inlet. A controlled study was designed to compare the effectiveness and complications in inserting the LMA when the cuff is fully deflated and partially inflated.

MATERIALS AND METHODS

American Society of Anesthesiologists physical status I or II 172 female patients scheduled for gynecologic procedures were included in this study. Patients were randomly allocated into one of the two groups; fully deflated (n=86) and partially inflated group (n=86). A size #4 LMA was inserted. The number of attempts, time taken for successful insertion, grade of leak, grade of fiberoptic view, and complications were evaluated.

RESULTS

All 172 patients completed the study protocol. The number of attempts, time taken for successful insertion, and grade of leak were not significantly different between the two groups. The grade of fiberoptic view and complications were lower in the fully deflated group.

CONCLUSION

The fully deflated method is more accurate and safe because of better fiberoptic view and lesser complications than the partially inflated group.

[Use of i-gel supraglottic airway for emergency airway management by novice personnel in comparison with laryngeal mask airway and tracheal intubation in manikin models]

BACKGROUND

Tracheal intubation (TI) is a difficult skill to acquire and its proficiency deteriorates over time if not regularly practiced. However, inexperienced personnel may be required to perform airway management in emergency situations. We compared a novel supraglottic device, i-gel, with laryngeal mask airway classic (cLMA) and TI devices in regard to total success count, time required for placement, and difficulties encountered by novice personnel using a manikin model.

METHODS

Following a brief training, 24 residents were asked to insert each of i-gel, cLMA, and TI in a randomize fasion using a manikin. Success counts for placement and time required to chest rise were recorded. After completing the tests, the participants scored the difficulty of each device using a visual ana-log scale (0-100 mm, very easy to very difficult).

RESULTS

The total success count with i-gel (46 times) was significantly higher than those of both cLMA (32 times) and TI (38 times), and the time to chest rise with i-gel (14 +/- 6 seconds) was significantly shorter than with cLMA (38 +/- 26 seconds). The difficulty score for i-gel (12 [0-51] mm) was significantly lower than those for both cLMA (51 [0-94] mm) and TI (25 [0-73] mm).

CONCLUSIONS

An i-gel may be useful for emergency airway management by inexperienced personnel. Further studies in a clinical setting are necessary to confirm these findings.

Indirect videolaryngoscopy with C-MAC D-Blade and GlideScope: a randomized, controlled comparison in patients with suspected difficult airways

BACKGROUND

Recently, indirect videolaryngoscopes have become increasingly important devices in difficult airway management. The aim of the present study was to investigate laryngoscopic view and intubation success using the new C-MAC® D-Blade in comparison to the established GlideScope® videolaryngoscope and conventional direct laryngoscopy in a randomized controlled trial.

METHODS

Ninety-six adult patients with expected difficult airways undergoing elective ear, nose and throat surgery (ENT) requiring general anesthesia were investigated. Repeated laryngoscopy was performed using a conventional direct Macintosh laryngoscope (DL), C-MAC D-Blade (DB) and GlideScope (GS) in a randomized sequence before patients were intubated with the last device used.

RESULTS

Both videolaryngoscopes showed significantly better C/L (Cormack-Lehane) classes than DL. Insufficient laryngoscopic view, defined as C/L ≥ III, was experienced in 18 patients (19.2%) with DL, in two patients with GS (2.1%) and in none with DB (0%). Time to best achievable laryngoscopic view did not differ between devices. Intubation time was significantly longer with both videolaryngoscopes (Median [Range] DB: 18 [8-33] s, and GS: 19 [9-34] s) than with DL (11 [5-26] s). However, intubation success was 100% for both DB and GS, whereas four patients could not be intubated using conventional direct laryngoscopy.

CONCLUSION

Compared to direct Macintosh laryngoscopy, both C-MAC® D-Blade and GlideScope® comparably resulted in an improved view of the glottic opening with successful tracheal intubation in all patients.