Difficult Ventilation Research Articles

Mitigation and Outcomes of Difficult Bag-Mask Ventilation in Critically Ill Children

AbstractDifficult bag-mask ventilation (BMV) occurs in 10% of pediatric intensive care unit (PICU) tracheal intubations (TI). The reasons clinicians identify difficult BMV in the PICU and the interventions used to mitigate that difficulty have not been well-studied. This is a prospective, observational, single-center study. A patient-specific data form was sent to PICU physicians supervising TIs from November 2019 through December 2020 to identify the presence of difficult BMV, attempted interventions used, and perceptions about intervention success. The dataset was linked and merged with the local TI quality database to assess safety outcomes. Among 305 TIs with response (87% response rate), 267 (88%) clinicians performed BMV during TI. Difficult BMV was reported in 28 of 267 patients (10%). Commonly reported reasons for difficult BMV included: facial structure (50%), high inspiratory pressure (36%), and improper mask fit (21%). Common interventions were jaw thrust (96%) and an airway adjunct (oral airway 50%, nasal airway 7%, and supraglottic airway 11%), with ventilation improvement in 44% and 73%, respectively. Most difficult BMV was identified before neuromuscular blockade (NMB) administration (96%) and 67% (18/27) resolved after NMB administration. The overall success in improving ventilation was 27/28 (96%). TI adverse outcomes (hemodynamic events, emesis, and/or hypoxemia <80%) are associated with the presence of difficult BMV (10/28, 36%) versus non-difficult BMV (20/239, 8%, p< 0.001). Difficult BMV is common in critically ill children and is associated with increased TI adverse outcomes. Airway adjunct placement and NMB use are often effective in improving ventilation.

AIRWAY MANAGEMENT GUIDELINES IN OBSTETRICS.

Anatomic and physiologic changes during pregnancy make it more difficult to establish a safe airway in pregnant women in case of the need for surgery under general anesthesia than in the non-obstetric population. The inability to ventilate and oxygenate is one of the most common causes of morbidity and mortality associated with general anesthesia for cesarean section. The aim of this paper is to present and analyze modern guidelines and algorithms for the management of difficult airway in obstetrics as an important segment of anesthesiology practice. Modern difficult airway management guidelines for pregnant women describe the procedure of difficult facemask ventilation, difficult airway management by using supraglottic devices, difficult endotracheal intubation, and emergency cricothyrotomy or tracheotomy in a situation where oxygenation and ventilation are impossible. Algorithms describe the procedures and equipment for each variant of difficult airway and decision-making strategies in situations when neither airway nor adequate oxygenation can be provided. Croatian anesthesiologists in most obstetric departments have appropriate equipment, as well as necessary experience in difficult airway management for pregnant women, and modern algorithms from the most developed countries can be adopted and accommodated to our daily practice, as well as incorporated into the training curricula of residents.

AIRWAY MANAGEMENT IN NEUROANESTHESIA.

Neurosurgical patients have specific airway management. Various conditions and diagnoses make intubation difficult and may also cause neurological damage. Spinal pathology, neurotrauma, cervical spine surgery, and pituitary gland surgery are just some examples. The aim of this review article is to present a broad spectrum of neurosurgical operations and potential complications in maintaining airway patency related to these issues. Quality perioperative preparation is a prerequisite to avoid the potentially irreversible consequences of difficult airways with a poor neurological or even fatal outcome. Patients with tumors of the pituitary region who present with Cushing's disease are prone to difficult ventilation, tracheal obstruction and difficult intubation. Awake craniotomy is also a challenge for the anesthesiologist, given that access to the airway is problematic due to the fixed frame. Unstable cervical spine occurs in cases of rheumatoid arthritis or blunt trauma, requiring precautions to be taken with spinal stabilization during intubation and induction. Pharyngeal edema and hematomas, possible complications of cervical spine surgery can endanger airway patency after extubation; postoperative patient supervision is thus required. Due to the potential threat to the patient's airway during neurosurgical procedures, quality anesthetic preoperative preparation is necessary to avoid irreversible damage and death.

Risk patterns of consecutive adverse events in airway management: a Bayesian network analysis

BackgroundMinor adverse airway events play a pivotal role in the safety of airway management. Changes in airway management strategies can reduce such events, but the broader impact on airway management remains unclear. MethodsMinor, frequently occurring adverse airway events were audited before and after implementation of changes to airway management strategies. We used two Bayesian networks to examine conditional probabilities of subsequent airway events and to compute the likelihood of certain events given that certain previous events occurred. ResultsIndependent of sex, age, and American Society of Anesthesiologists physical status, targeted changes to airway management strategies reduced the risk of a first event. Obese patients were an exception, in whom no risk reduction was achieved. Frequently occurring event sequences were identified, for example the most likely event to follow difficult bag-mask ventilation was a Cormack–Lehane grade ≥3, with a risk of 14.3% (95% credible interval [CI], 11.4–17.2%). An impact of the targeted changes was detected on the likelihood of some event sequences, for example the likelihood of no consecutive event after a tracheal tube-related event increased from 43.3% (95% CI, 39.4–47.6%) to 56.4% (95% CI, 52.0–60.5%). ConclusionsIdentification of risk patterns and typical structures of event sequences provides a clinically relevant perspective on airway incidents. It further provides a means to quantify the impact of targeted airway management changes. These targeted changes can influence some event sequences, but overall, the benefit results from the cumulative effect of improvements in multiple events. Targeted airway management changes with knowledge of risk patterns and event sequences can potentially further improve patient safety in airway management. Clinical trial registrationNCT02743767.

USE OF VIDEO LARYNGOSCOPE FOR DIFFICULT AIRWAY MANAGEMENT IN THORACIC SURGERY: A CASE STUDY

We present the clinical case of a 76-year-old male with the following medical history: Active smoker (2 packs/day),moderate obesity, moderate COPD. arterial hypertension, mellitus diabetes 2, dyslipidemia. Lacunar stroke without neurological damage, infrarenal abdominal aortic aneurysm of 40 mm, under follow-up in policlinic of Vascular Surgery, 1st degree atrioventricular block, under follow-up by Cardiology. Normal Echocardiography. PET-CT: Hypermetabolic pulmonary nodule in RUL, suggestive of cancer. FUNCTIONAL TESTS: Moderate obstructive pattern. FEV1 2.20 (72%), FEV1/FVC 58. DLCO 5.80 (64%). AIRWAY EXPLORATION: Retrognatia, Mallampati III, significant cervical stiffness, thick neck and degree of movement of head and neck < 80°. Case Management: Placement of thoracic epidural catheter (T5-T6) prior to induction for analgesic control during intraoperative and postoperativeperiod. Non-invasive blood pressure monitoring, 5-lead ECG, temperature, peripheral oxygen saturation (SpO2), Bispectral Index (BIS) and Train-of-four (TOF). In the presence of predictors of possible difficult airway and ventilation, material is prepared for management of possible difficult airway Pre-oxygenation with face mask and FiO2 1 until EtO2 85 mmHg is reached. Rapid sequence induction was performed with intravenous midazolam, fentanyl, propofol and 1,2 mg/kg of rocuronium. After reaching TOF 0, direct laryngoscopy was initially performed but a Cormark-Lehane (CL) III was observed.Indirect laryngoscopy was then performed with a McGrath video laryngoscope with a n°4 disposable blade, showing a CL I. Subsequently, an 11 Fr airway exchange catheter was introduced through the vocal cords into the trachea; then, the proximal end of the airway exchange catheter was inserted into the endobronchial lumen of the 37Fr Vivasight DL, to permet its insertion into the trachea guided by this airway exchange catheter under the vision of the McGrath videolaryngoscope. Once the VivaSight DL was inserted into the trachea, the airway exchange catheter was removed and the VivaSight DL tube was turned left 90° and was inserted successful into the left main bronchus guided by embedded camera of this special type of DLT. Anesthesia maintenance was performed with inhalated sevoflurane and continuous intravenous infusion of remifentanil and rocuronium. Epidural elastomer of levobupivacaine 0.125% at 7 ml/h. Controlled ventilation is maintained in volume control mode, with Tidal Volume (TV) at 7 ml/kg ideal weight in two-lung ventilation and 5 ml/kg ideal weight in one-lung ventilation. Alveolar Recruitment Maneouvres (ARM) after intubation and at start of one-lung ventilation (OLV) were performed. Good mechanics and adequate gas exchange throughout the procedure, with no episodes of desaturation. After completion of surgery, reversal of neuromuscular blockade was achieved with sugammadex at 2 mg/kg. After checking TOF ratio> 90% and adequate level of consciousness, optimal respiratory mechanics and a 100% SpO2, extubation was performed without incident. He was transferred to the intensive care unit for post-surgical control during the first 24 hours.

A case of unexpected intraoperative airway obstruction in a patient with an aneurysm of the ascending aorta and aortic arch.

Upper airway compression is one of the clinical manifestations of thoracic aortic aneurysm, which is associated with poor prognosis and high mortality. A 44-year-old patient with ascending aortic and arch aneurysm who was scheduled for Bentall surgery and total arch replacement under cardiopulmonary bypass suffered difficult ventilation after endotracheal intubation. The patient did not exhibit any positional dyspnoea or orthopnoea, did not show any difficulties in the supine position, and had no noteworthy medical history. However, we encountered unexpected hypoventilation after intubation. Isoprenaline infusion was effective while emergency cardiopulmonary bypass was established to deal with this crisis. Fibreoptic bronchoscopy revealed complete obstruction of the carina and confirmed the supracarinal position of the tube. Complete airway obstruction may occur even if there are no symptoms before surgery in patients with thoracic aortic aneurysm. Comprehensive preoperative assessment, a well-developed airway management plan, and responses to possible emergencies are essential to reduce unnecessary events or complications.

Potential effect of agomelatine versus dexmedetomidine during awake fiberoptic intubation; role of catacholamine

Background Awake fiber-optic intubation is one of the recommended strategies for surgical patients with suspected difficult airway, especially when simultaneous difficult ventilation is anticipated. Patients and methods In all, 90 patients of both sexes aged between 20 and 55 years, American Society of Anesthesiologist I and II stages were scheduled for elective abdominal surgeries. Patients were randomized into three equal groups. Group A: oral agomelatine at a dose of 10 mg administered with a sip of water 120 min before surgery. Group B: agomelatine+dexmedetomidine. Group C: dexmedetomidine infused at a dose of 1 μg/kg loading infusion per 10 min followed by a continuous infusion of 0.2 μg/kg/h. The following variables (mean arterial pressure, heart rate, oxygen saturation, cough score, postintubation score) and Richmond agitation sedation scale score were recorded in addition to the serum level of norepinephrine. Conclusion Agomelatine is more effective than dexmedetomidine in making better intubation state with sedation, less desaturation, and hemodynamic stability during awake fiber-optic intubation. Synergestic effect between agomelatine and dexmedetomidine was detected.

Anesthetic management in a patient with severe tracheal stenosis by monitoring oxygen reserve index

BackgroundGeneral anesthesia for tracheal stenting is challenging because of difficult ventilation and accompanying hypoxia. We report the use of oxygen reserve index (ORi™) during tracheal stenting.Case presentationCauterization of an intratracheal tumor and tracheal stenting was scheduled in a patient. ORi decreased from 0.3 to 0.2 after starting cauterization using a flexible bronchoscope through a tracheal tube with 28% oxygen, while SpO2 was maintained at 100%. ORi further decreased to 0, followed by a decrease of SpO2 < 90%, and surgery was interrupted. SpO2 was increased shortly after increasing FiO2 to 1.0, but ORi remained 0 when surgery was resumed; it was increased after completion of cauterization. Both ORi and SpO2 were maintained above 0.4 and 98%, respectively, during tracheal stenting through a rigid bronchoscope under intrapulmonary percussive ventilation.ConclusionORi was useful for predicting a decrease of SpO2 under general anesthesia for tracheal stenting.

Study on Optimization of Tunnel Ventilation Flow Field in Long Tunnel Based on CFD Computer Simulation Technology

With the rapid development of tunnel construction, more and more long tunnels are being designed and built. In contrast to ordinary tunnels, long tunnels are characterized by large construction distances and difficult ventilation. In this study, gallery ventilation systems in the construction of long tunnels were studied. Combined with the CFD software FLUENT, a three-dimensional model of tunnel ventilation of a double tunnel was established, and a numerical simulation analysis of the ventilation flow field was carried out and optimized the flow field of gallery ventilation. We found that the main circulation air flow of gallery ventilation was formed by the jet fan, which was installed near the air flow-in tunnel. We also determined the main factors that affect the ventilation effect in gallery ventilation, including the wind wall formed by the high-speed airflow at the cross-aisle and found that the draft fan in front of the cross-aisle could eliminate the wind wall and improve the ventilation effect. The influence of the location and type of the draft fan on the elimination of air flow structure was studied, and the best fan layout scheme suitable for the site was determined. The ventilation scheme of the tunnel was optimized.

Difficult Ventilation in an Infant After Successful Intubation.

Manufacturing defects in the connector of the endotracheal tube are not frequently encountered in emergency and planned intubations. In cases where they are encountered, however, they may cause partial or complete airway obstruction in sick infants with limited reserves, giving rise to a life-threatening situation following the intubation. For this reason, endotracheal tubes must be checked carefully before use. To this end, a stylet can be passed through the tube to check for a defect in the tube lumen or tube connector as part of a routine check of an endotracheal tube. This report features a patient who experienced a complete airway obstruction following intubation due to a manufacturing defect in the connector of the endotracheal tube.

Anaesthetic Management in Mucopolysaccharidoses Patients: Clinical Experience in a Tertiary Hospital.

Introduction: Mucopolysaccharidoses (MPS) are a group of rare inherited metabolic diseases caused by the deficiency of enzymes required to degrade glycosaminoglycans (GAGs) in the lysosome with progressive and multiorgan involvement. Due to its progressive nature, a large number of patients need surgical intervention, which is associated with higher perioperative morbidity.Methods: We retrospectively reviewed 29 medical records regarding the peri and post-operative anaesthetic care of 10 children with mucopolysaccharidoses at a tertiary hospital in Northern Portugal between 2010 and 2021. A comprehensive review of the literature is also included.Results: Twenty-nine medical records of 10 patients with a mean age of 8.8 years old were included. At the time of the procedure, 65.5% of patients were under enzymatic replacement and all had some type of organ involvement.Each patient was subjected to 2.9 elective procedures on average, with the lowest age of two years at the first procedure. Regarding surgical specialties, 41.4% of interventions were orthopaedic. Balanced anaesthesia with inhalational induction and spontaneous breathing was performed in 48.3% of cases, with no reports of difficult bag-mask ventilation. Endotracheal intubation in the operating room was performed in nine cases. Direct laryngoscopy with a Macintosh blade was the first option in seven patients. Success was achieved only in three cases. Failed intubation was managed with a paediatric C-MAC® video laryngoscope (VLG; one case) and fiberoptic bronchoscopy (two cases). Video laryngoscopy and fibroscopy were the first choices in one case each. Post-operative complications were registered in 10 procedures (34.5%), with airway and pulmonary complications in 17.2%. All complications occurred in different patients except for post-operative nausea and vomiting, which were registered in three cases, two of them in the same patient at different orthopaedic surgical interventions.Discussion: The high percentage of direct laryngoscopy could be related to the greater number of interventions performed in a period when indirect methods were not so widely used in anaesthetic practice, and the high rate of failure highlights the importance of transitioning to indirect techniques upon the first attempt. The high percentage of patients under enzymatic treatment can explain the low number of adverse airway events. High-quality evidence regarding MPS is lacking in the literature. Prospective studies would improve the perioperative care of this particular subset of patients.Conclusion: Patients with MPS represent a huge challenge for the anaesthesiologist, mainly in view of airway management. The integration of all available data in clinical practice is essential to optimize perioperative management of mucopolysaccharidoses patients’ management and improve clinical outcomes.

Warning Model of Coal Mine Ventilation Disaster Based on the Combination of K-Neighborhood-Gray Correlation Method and Its Application

The abnormalities in the mine ventilation system can reflect the risks and hidden dangers during the mine production. By combining the basic information of the mine and the ventilation monitoring data with the production status, the gas concentration and wind speed are used as the calculation indicators, and the k-nearest neighbor (KNN) is used to study the abnormal change characteristics of calculation indicators of mine ventilation system in different ventilation periods, and a ventilation hazard warning model was constructed and the model results were compared and validated. In addition, the dominant factors of the warning level were obtained by combining the grey correlation analysis (GCA). The results show that under different ventilation periods (easy ventilation period and difficult ventilation period), the correct rates of calculation and verification in easy ventilation period and difficult ventilation period are 95.65% and 97.82% respectively. It can be seen that the accuracy of the warning model is over 95%, which has good application and promotion value. Furthermore, the correlation coefficient of the wind speed in two periods is relatively high, which is indicating that the speed is the main indicator that affects the warning level. The research of this paper can provide theoretical support for realizing the intelligent management of mine risk in advance and short-term early warning.

Dynamic Obstruction due to Unfurling of Spirals in a Flexometallic Tube.

Flexometallic tubes are kink-resistant and extensively used in neurosurgeries. The manufacturers of flexometallic tubes recommend single usage. In low-income countries, due to the cost restraints, flexometallic tubes are commonly reused after ethylene oxide sterilization. With this technique, flexometallic tubes are effectively sterilized, but the physical integrity of the endotracheal tube cuffs may be compromised.1 Tube kinking2 and intraluminal blebs due to dissection3 are observed with the reused flexometallic tubes. These obstructions lead to difficulty in ventilation and inability to pass a suction catheter freely. Flexometallic tubes should be thoroughly checked for external deformity, cuff integrity, and tube patency for safe reuse.Despite thorough assessment of reused flexometallic tubes, the partial unfurling of nylon spirals with distal herniation into the tube (fig.) may still happen intraoperatively, leading to dynamic obstruction resulting in variable resistance during suction catheter negotiation (see Supplemental Digital Content 1, video S1, http://links.lww.com/ALN/C848). Along with the heavy weight of the circuit, the varied positions of head and neck result in additional rotational bending of flexometallic tubes, contributing to partial unfurling, which may not cause complete airway obstruction but can lead to difficult ventilation requiring airway change. The simple technique of passing a suction catheter through flexometallic tubes can help in identifying such partial tube obstruction. Reinforced tracheostomy tubes are also frequently reused after a thorough cleaning and visual inspection.Adhering to the manufacturer’s recommendation regarding reuse is the best way to prevent these complications. However, when clinically necessary and under the right circumstances only, flexometallic tubes should be reused after a thorough assessment.The authors are thankful to the patient who consented to publish the current article. The authors are also thankful to all anesthesia technicians who helped them ensure patient safety.The authors declare no competing interests.

Emergent Surgical Airway Skills: Time to Re-evaluate the Competencies.

IntroductionOne of the most challenging scenarios an anesthesia provider can face is treating a can't intubate can't ventilate (CICV) patient. The incidence of CICV is estimated to be around one in 10,000 cases. According to the American Society of Anesthesiology Closed Claims Study, adverse respiratory events are the most common type of injury, with difficult intubation and ventilation contributing to the majority of these cases. The objective of this non-interventional quality improvement project was to evaluate the prior training, exposure, and self-reported confidence in handling the CICV scenario among anesthesia providers at Henry Ford Hospital in Detroit, MI.MethodsAn online questionnaire was distributed via email to all residents, certified registered nurse anesthetists (CRNAs), and attending anesthesiologists in March 2021. The email contained a link to an online questionnaire via Microsoft Forms (Microsoft Corporation, Redmond, WA). Univariate group comparisons were carried out between the respondents’ role (attending, CRNA, or resident), as well as between the number of years that the respondents were in practice (< 5 years, 5-10 years, > 10 years).ResultsOut of the total 170 anesthesia providers, 119 participated in the study where 54 (45%) were attendings, 44 (37%) were residents, and 21 (18%) were CRNAs. The majority (75%) did not know the surgical airway kit location, and 87% had not performed the surgical airway procedure before. The vast majority (96.7%) recommended simulation training compared to online training or lecture series, and just over 50% recommended annual training frequency. When looking at the differences in responses based on years of experience as an anesthesia provider, the majority of those with > 10 years in practice knew how to perform the surgical airway technique while respondents with < 5 years did not know how to perform the technique, and 50% of those with five to 10 years experience knew how to perform the surgical airway procedure for a CICV scenario.ConclusionAlthough there were many significant differences observed between the various provider roles and years in practice, surprisingly, the responses revealed both a lack of experience and confidence in performing the surgical airway procedure in all provider roles. These findings highlight a need for better emergency airway teaching and training. These findings will be used to guide the design and implementation of improved surgical airway training for residents, CRNAs, and attending anesthesiologists with the goal of better preparedness for handling a CICV scenario.

A Decision Tree Approach to Airway Management Pathways in the 2022 Difficult Airway Algorithm of the American Society of Anesthesiologists.

The American Society of Anesthesiologists’ (ASA) Task Force on Management of the Difficult Airway has developed a decision tree tool that uses inductive assessments to guide the anesthesiologist’s choice of pathway in the ASA’s Difficult Airway Algorithm. The tool prompts the anesthesiologist to consider the risk of difficulty with laryngoscopy (direct or indirect) and tracheal intubation, facemask or supraglottic ventilation, gastric contents aspiration, and rapid oxyhemoglobin desaturation. For every airway management event, the approach integrates the anesthesiologist’s unique combination of experience, expertise, patient anatomy and disease, equipment availability, and other contextual conditions into the decision process. Entry into the awake intubation pathway is encouraged when the patient is judged at risk of difficult tracheal intubation and one or more of the following: difficult ventilation, significant aspiration risk, and/or rapid oxyhemoglobin desaturation. The decision tree tool is anticipated to improve communication between anesthesiologists and others by clearly identifying those factors of concern and how decision-making is affected by those concerns.

Incidence and Predictors of Difficult Mask Ventilation in High-Risk Adult Population Scheduled for Elective Surgery: A Prospective Observational Study.

IntroductionMask ventilation is one of the key components in the management of airway during general anaesthesia, particularly when laryngoscopy is challenging. Adequate mask ventilation provides anaesthesiologists a safe time in case of unanticipated or anticipated difficult airway situations. The aim of this study was to determine the incidence of difficult bag-mask ventilation and intubation in patients having three or more predictors for difficult mask ventilation (DMV) in adult patients scheduled for elective surgery under anaesthesia.MethodsA total of 294 patients requiring endotracheal intubation for elective surgical procedure having three or more risk factors were evaluated for the presence of difficulty in bag-mask ventilation and intubation by the anaesthesiologist. Chi-square test or Fisher's exact test and a multivariable stepwise logistic regression model were performed to identify predictors of DMV. Crude and adjusted odds ratio with 95% confidence interval were reported.ResultsIn this study, the average age of the patients was 53.59±13.32 years with a 2:1 male-to-female ratio. DMV and difficult intubation (DI) were observed in 31.6% and 3% of patients, respectively. Multivariate analysis identified history of snoring, BMI (>35 kg/m2), presence of beard and Mallampati III or IV as independent predictors for DMV. Patients with multiple factors (≥3 factors) had a threefold (OR=2.57) increased risk of difficulty in mask ventilation and a nearly fivefold (OR=4.63) increased risk of difficulty with intubation.Conclusion In our study, the incidence of DMV was observed in 93 (31.6%) patients and DI was found in 9 (3%) patients. A simple DMV risk score may help to predict DMV better, potentially improving safety during difficult airway management, decreasing morbidity and mortality associated with it.

Is Airway Management More Risky in Bariatric Surgery?

Airway problems may be experienced more often during anesthesia management in bariatric surgery. In this prospective study, we aimed to compare the incidence of difficult ventilation and intubation between bariatric surgery and other surgeries. This was a case-control study. Medical records of 156 patients over the age of 18 who were scheduled for bariatric (n=68) and nonbariatric surgery (n=88) under general anesthesia were evaluated. The percentage of ASA III, diabetes mellitus, and obstructive sleep apnea syndrome (75%, 33.8%, and 16.2%, respectively) was significantly higher in bariatric surgery patients compared to nonbariatric patients (14.8%, 10.2%, and 3.4%, respectively). No significant difference was found in mean thyromental distance and history of difficult intubation, restriction of cervical extension, beard presence, tooth loss, mallampati, Cormack-Lehane score, intubation score, difficult ventilation, difficult intubation and intubation device used. An increase in neck circumference (>50 cm) rather than body mass index was a more significant indicator in predicting difficult intubation and difficult ventilation. The incidences of difficult ventilation and difficult intubation were similar in bariatric and nonbariatric surgeries in circumstances where the necessary equipment and experienced anesthesiologists are available.

Retrograde Intubation for Airway Management of Firearm Injury in the Maxillofacial Region

Endotracheal intubation is one of the most important anaesthetic skills. Trauma to the maxillofacial region is challenging in terms of airway management. Airway management in such patients is difficult and decides the survival of the patient. Endotracheal intubation in patients with difficult ventilation and difficult intubation always remains a challenge, especially in the absence of a flexible fibreoptic bronchoscope. The retrograde catheter technique is an acceptable option for airway management in cases where oral intubation is not possible because of difficult airway or is not recommended because of fear of dislodgement of fractured segments of facial bones. The author here reports a case of a 30-year-old male with firearm injury in maxillofacial region posted for emergency surgery with anticipated difficult airway. Emergency retrograde intubation was done for the management of airway with successful outcome.

Predictive Values of LEMON and LEON Scores in Elective Oral and Maxillofacial Surgery- Correlation with Intubation Difficulty Scale

Introduction: Airway management can be a major concern, due to the possibility of encountering difficult ventilation and intubation. The Modified Intubation Difficulty Scale (MIDS) is a quantitative scale that can objectively compare nasotracheal intubation. LEMON method which consists of following assessments; Look-Evaluate-Mallampati-Obstruction-Neck mobility and modified LEMON scores (LEON) are popular scoring systems described for airway management due to their easy usability. We aimed to evaluate usability of the LEMON and LEON scores in patients who underwent oral and maxillofacial surgery by studying correlation between each score and the MIDS. Materials and Methods: The records of 72 patients were reviewed retrospectively. At the pre-anesthetic evaluation; airway assessments were recorded according to LEMON, LEON scores; MIDS were recorded after intubation. Patients were allocated into two groups: Non-difficult (NonD; MIDS ≤5) and Difficult (D; MIDS &gt;5). Correlations between scores were analyzed using Spearman’s rank correlation. Receiver operating characteristic (ROC) curve plots were used to determine possible cut-off values; specificity, sensitivity, negative-predictive values for LEON and LEMON scores. In all analyses, p&lt;0.05 were considered statistically significant. Results: LEMON and LEON scores were correlated with the MIDS. Analysis of ROC curve plots revealed 2 cut-off values (≥4 and ≥5) for LEMON; 1 cut-off value (≥4) for LEON score. Among the scores, LEMON (≥4), LEON had the highest sensitivity and negative-predictive values (both 100%); LEON showed higher specificity than the LEMON (≥4) (96.7% vs 91.8%). LEMON (≥5) had the highest specificity (98.4%) but the lowest sensitivity (90.4%), negative-predictive value (90.9%) among the group. Conclusion: LEON scores ≥4 can be effectively used with 100% sensitivity, 96.7% specificity and, 100% negative-predictive-value for predicting difficult airway and intubation in elective maxillofacial surgeries. Keywords: Oral and maxillofacial surgery, airway assessment, LEON Score, LEMON Score, Modified Intubation Difficulty Scale

Difficult Ventilation in a patient after Endotracheal Intubation: an Unusual Manufacturing Defect in E.T.T. Connecter

Summary: Airway resistance depends upon the diameter of endotracheal tube (E.T.T) and other respiratory organs. Actually resistance to flow through a tube increases up to sixteen times if diameter is reduced to half of the original size. Disposable E.T.T which are currently used in anaesthesia practice are made up of P.V.C with a connecter which is fitted on proximal end of endotracheal tube and proximal end of connector I attached with breathing circuit. Usually the internal diameter of connector should be equal to internal diameter of endotracheal tube.