Impact of bed angle and height on intubation success during simulated endotracheal intubation in the ramped position

OBJECTIVE

The ramped position is often used during endotracheal intubation to improve oxygenation, improve laryngeal views, and reduce airway complications. We sought to compare the impact of ramp angle and bed height on intubation outcomes during simulated endotracheal intubation.

METHODS

We enrolled emergency medicine residents and fourth-year medical students to perform simulated direct laryngoscopy and endotracheal intubation in random order with the mannequin in the following combinations of ramp angles and bed heights; ramp angles of 25° and 45° at bed heights including knee, mid-thigh, umbilicus, xiphoid, and nipple/intermammary fold. Our primary outcome was the reported percentage of glottic opening (POGO) score. Secondary outcomes included number of laryngoscopy attempts and intubation time.

RESULTS

We enrolled 25 participants. There was no difference in reported POGO scores at 25° between bed heights, but at 45°, the umbilicus bed height had an improved reported POGO score (20; 95% confidence interval [CI] 7-33, P < 0.01) relative to xyphoid. The nipple/inframammary fold height required longer intubation times in seconds (mean difference [MD] 95% CI) at 25°, (MD, 23.9 [4.6-37.6], P < 0.01) and more laryngoscopy attempts at 45° (MD, 0.48 [0.16-0.79], P < 0.01) relative to xyphoid. There was no difference in laryngoscopy attempts and video POGO between 25° and 45° at all bed heights, but reported POGO at the umbilicus position was better at 25° than 45° (12 [1-23], P = 0.03).

CONCLUSION

The umbilicus bed height resulted in the highest reported POGO at 45°. Nipple/inframammary fold height resulted in worse intubating conditions.

Floppy epiglottis together with extra-laryngeal mass causing an inducible laryngeal obstruction and hypoxemic event in an adult: A case report

Floppy epiglottis in an adult is rare and often pathological. Airway obstruction caused by floppy epiglottis in an adult is rarely reported. Neck mass, however, can affect the airway in many ways; however, inducible upper airway obstruction by extra-laryngeal neck mass is hardly been reported. In most of the instances of inducible laryngeal obstruction, the tumor is found in and around the laryngeal inlet. Herein, we report such an unusual incident happened to a 40-year-old gentleman, a case of oral carcinoma for 3 months and a rapidly increasing swelling (6 × 5 cm) over the right side of the neck for 8 days. He presented to us for emergency tracheostomy with the feature of acute upper airway obstruction, unable to lie down; and having difficulty in breathing, desaturation, and chocking even in propped up position. The case highlights the importance of clinical findings and difficulties faced for airway management in such patients.

Post-Exposure Anti-Ricin Treatment Protects Swine Against Lethal Systemic and Pulmonary Exposures

Ricin, a plant-derived toxin originating from the seeds of Ricinus communis (castor bean plant), is one of the most lethal toxins known. To date, there is no approved post-exposure therapy for ricin exposures. This work demonstrates for the first time the therapeutic efficacy of equine-derived anti-ricin F(ab’)₂ antibodies against lethal pulmonary and systemic ricin exposures in swine. While administration of the antitoxin at 18 h post-exposure protected more than 80% of both intratracheally and intramuscularly ricin-intoxicated swine, treatment at 24 h post-exposure protected 58% of the intramuscular-exposed swine, as opposed to 26% of the intratracheally exposed animals. Quantitation of the anti-ricin neutralizing units in the anti-toxin preparations confirmed that the disparate protection conferred to swine subjected to the two routes of exposure stems from variance between the two models. Furthermore, dose response experiments showed that approximately 3 times lesser amounts of antibody are needed for high-level protection of the intramuscularly compared to the intratracheally intoxicated swine. This study, which demonstrates the high-level post-exposure efficacy of anti-ricin antitoxin at clinically relevant time-points in a large animal model, can serve as the basis for the formulation of post-exposure countermeasures against ricin poisoning in humans.

Decreasing Unplanned Extubation in the Neonatal ICU With a Focus on Endotracheal Tube Tip Position

BACKGROUND

Unplanned extubation (UE) is an important quality metric in the neonatal ICU that is associated with hypoxia, bradycardia, and risk for airway trauma with emergent re-intubation. Initial efforts to reduce UE in our level 4 neonatal ICU included standardized securement of the endotracheal tube (ETT) and requiring multiple providers to be present for ETT adjustments and patient positioning as phase 1 interventions. After an initial decline, the UE rate plateaued; an internal retrospective review revealed that the odds of UE were 2.9 times higher in the setting of an ETT tip at or above T1 (high ETT) on chest radiograph just prior to UE. The team hypothesized that advancing ETT tips to below T1 would reduce UE risk in infants of all gestational ages.

METHODS

Over a period of 32 months, we compared pre-intervention and post-intervention UE rates in our neonatal ICU after a 2-step initiative that focused initially on ETT securement and assessment, with a subsequent addition of a single intervention to advance ETT tips below T1. To determine if the decrease in UE rate could be secondary to our intervention, data were analyzed from 3 cohorts: a control group of 40 infants with 185 chest radiographs and no UEs, 46 infants with chest radiographs prior to 58 UE events before the intervention, and 37 infants with chest radiographs prior to 48 UE events following the intervention.

RESULTS

Advancing ETT tips below T1, in addition to the use of a standard UE-prevention bundle, led to a significant decrease in the UE rate from 1.23 to 0.91 UEs per 100 ventilator days, with 14% of postintervention UEs attributed to ETT advancement.

CONCLUSIONS

High ETTs are significantly associated with UEs in the neonatal ICU. Optimizing ETT position may be an underrecognized driver in the provider's toolbox to reduce UEs. Because ETT repositioning carries risk of UE, extra caution should be taken during advancement.

The Changes of Endotracheal Tube Cuff Pressure during Manual and Intermittent Controlling in Intensive Care Units

BACKGROUND

Usually, the endotracheal tube cuff pressure is controlled by cuff pressure monitoring. However, the intermittent pilot-manometer connection and disconnection may cause a change in the adjusted pressure. This study aimed to investigate changes in the endotracheal tube cuff pressure using both manual and intermittent controls.

MATERIALS AND METHODS

A semi-experimental within-subject design was conducted. Fifty-nine intubated patients in the Mazandaran Intensive Care Units (ICUs) participated through convenience sampling in 2018. In the control condition, first, the cuff pressure was adjusted in 25 cm H2O then it was measured without manometer-pilot disconnection at 1 and 5 min intervals. In the intervention condition, cuff pressure was immediately adjusted in 25 cm H2O then it was measured with manometer-pilot disconnection in the 1st and 5th minutes. Data analysis was performed using Independent t-test, Chi-square test, and Phi coefficient.

RESULTS

The mean and Standard Deviation (SD) change of cuff pressure after 1 minute, from 25 cm H2O, in the intervention condition was 20.22 (3.53) cm H2O. The mean (SD) of this change in the control condition was 25.22 (3.39) cm H2O. This difference was significant (t 116 = 7.83, p < 0.001, d = 1.44). The mean (SD) change of cuff pressure after 5 minutes, from 25 cm H2O, in the intervention condition was 19.11 (2.98) cm H2O. The mean (SD) of this change in the control condition was 25.47 (4.53) cm H2O. This difference was significant (t 116 = 9.24, p < 0.001, d = 1.70).

CONCLUSIONS

The tracheal tube cuff pressure has been significantly reduced during manual intermittent measuring. Therefore, it is suggested that continuous cuff pressure monitoring and regulation should be used.

Single-Centre Open-Label Comparative Trial of Video-Assisted Fibreoptic-Bronchoscope-Guided Oral Versus Nasal Intubation in Anaesthetised Spontaneously Breathing Paediatric Patients

Objective

Flexible fibreoptic intubation is challenging in paediatric patients. Very few studies have compared fibreoptic intubation via oral and nasal routes in children. We hypothesised that the total time to a successful fibreoptic-guided tracheal intubation would be faster through the nasal route when compared to the oral route.

Methods

Sixty children aged 6–12 years were randomised to receive fibreoptic tracheal intubation through oral (group FOI) or nasal route (group FNI). We measured the time to glottic view and total time to successful tracheal intubation. The number of attempts needed, first attempt and overall success rate, external manoeuvres needed to obtain an adequate laryngeal view, subjective assessment of ease of intubation and complications, if any, were also recorded.

Results

The time to glottic view (76.26±.7 s vs. 46.33±16.9 s; p=0.001) and total intubation time (4.55±1.07 min vs. 3.05±0.60 min; p<0.0001) were significantly higher in the FOI group as compared to the FNI group. An overall success rate was 100% in the FNI group and 96.6% in the FOI group. The haemodynamic parameters (mean heart rate and blood pressures) changes were comparable in the two groups at all time intervals. The subjective assessment of ease of intubation was comparable in the two groups (p=0.21). Complications were minor and self-limiting.

Conclusion

Intubation guided by a nasal flexible fibreoptic bronchoscope is easier and faster when compared to oral intubation in children aged 6–12 years with normal airway, and it should be preferred for intubation in children requiring fibreoptic intubation.

Coxiella burnetii Intratracheal Aerosol Infection Model in Mice, Guinea Pigs, and Nonhuman Primates

Coxiella burnetii, the etiological agent of Q fever, is a Gram-negative bacterium transmitted to humans by inhalation of contaminated aerosols. Acute Q fever is often self-limiting, presenting as a febrile illness that can result in atypical pneumonia. In some cases, Q fever becomes chronic, leading to endocarditis that can be life threatening. The formalin-inactivated whole-cell vaccine (WCV) confers long-term protection but has significant side effects when administered to presensitized individuals. Designing new vaccines against C. burnetii remains a challenge and requires the use of clinically relevant modes of transmission in appropriate animal models. We have developed a safe and reproducible C. burnetii aerosol challenge in three different animal models to evaluate the effects of pulmonary acquired infection. Using a MicroSprayer aerosolizer, BL/6 mice and Hartley guinea pigs were infected intratracheally with C. burnetii Nine Mile phase I (NMI) and demonstrated susceptibility as determined by measuring bacterial growth in the lungs and subsequent dissemination to the spleen. Histological analysis of lung tissue showed significant pathology associated with disease, which was more severe in guinea pigs. Infection using large-particle aerosol (LPA) delivery was further confirmed in nonhuman primates, which developed fever and pneumonia. We also demonstrate that vaccinating mice and guinea pigs with WCV prior to LPA challenge is capable of eliciting protective immunity that significantly reduces splenomegaly and the bacterial burden in spleen and lung tissues. These data suggest that these models can have appreciable value in using the LPA delivery system to study pulmonary Q fever pathogenesis as well as designing vaccine countermeasures to C. burnetii aerosol transmission.

Long-term effects of the intratracheal administration of corticosteroids for the prevention of bronchopulmonary dysplasia: A meta-analysis

BACKGROUND

Bronchopulmonary dysplasia (BPD) is one of the most common complications in premature infants. Since inflammation plays a crucial role in the pathogenesis of BPD, anti-inflammatory drugs, such as corticosteroids, have long been the focus of prevention research. In this meta-analysis, we aim to explore the long-term effects of the intratracheal administration of corticosteroids (IAC) in preventing BPD.

METHODS

EMBASE, MEDLINE, the Cochrane Library, Web of Science, CINAHL, Clinicaltrials.gov, the ISRCTN registry, and gray literature were searched to identify randomized controlled trials (RCTs) that evaluated the long-term effects of IAC for the prevention of BPD in premature infants.

RESULTS

Five RCTs (n = 1515) were eligible for further analysis. The meta-analysis revealed that the incidence of neurodevelopmental impairment (NDI) did not significantly differ between the IAC group and the control group (relative risk [RR] 0.9, 95% confidence interval [CI] 0.79 to 1.03, P = .14). There was no significant reduction in long-term mortality (RR, 1.13; 95% CI, 0.9 to 1.41; P = .3) or the incidence of rehospitalization (RR, 0.99; 95% CI, 0.89 to 1.09, P = .82). No significant differences were observed between the IAC group and the control group with regard to height, weight and head circumference at the age of 18 to 36 months of postmenstrual age (PMA) (mean difference [MD], 0.14; 95% CI, -0.26 to 0.54, P = .48).

CONCLUSIONS

Our study suggests that IAC in preterm infants does not have significant long-term benefits or adverse outcomes. However, before routine use, well-designed studies and studies involving large sample sizes are needed to confirm the pharmacokinetics and long-term effects of IAC.

Effects of intubation with a double-lumen endotracheal tube on intraocular pressure during rapid sequence induction using succinylcholine chloride in patients with or without underlying systemic hypertension

Background

Tracheal intubation is closely associated with increases in intraocular pressure (IOP); however, the effects of double-lumen tube (DLT) intubation on IOP have not been validated. Systemic hypertension (HTN) is another factor that may increase IOP. In this study, we observed differences in IOP increases between DLT and singlelumen tube (SLT) intubation, and evaluated the influence of underlying HTN during rapid sequence induction.

Methods

Sixty-eight patients were allocated into one of the following group: SLT/without HTN (n = 17), SLT/HTN (n = 17), DLT/without HTN (n = 17), and DLT/HTN (n = 17). An SLT was inserted for orthopedic or gynecological surgery, and a DLT was inserted for lung surgery after rapid sequence induction using succinylcholine. IOP was measured before anesthetic induction and until 10 min after intubation using a handheld tonometer (Tono-Pen AVIA^®).

Results

In the DLT/without HTN and DLT/HTN groups, the maximum increases in IOPs after tracheal intubation were 7.9 and 12.2 mmHg, respectively, compared to baseline. In the SLT/without HTN and SLT/HTN groups, the maximum increases were 5.0 and 4.9 mmHg, respectively, compared to baseline. In comparisons between patients with and without underlying HTN, the values of IOPs were comparable.

Conclusions

Tracheal intubation with a DLT is associated with more increases in IOPs than with an SLT in rapid sequence induction. Well-controlled underlying hypertension did not increase IOP during tracheal intubation.

Implications of the presence of yeasts in tracheobronchial secretions of critically ill intubated patients

The presence of some microorganisms in the respiratory tract is a known risk factor for the infection of air passages; however, it is not clear whether this holds true for Candida spp. Thus, our objective was to determine the frequency of yeast colonization in the tracheobronchial secretions of critically ill intubated patients and to assess the presence of these yeasts in the infra-cuff region of the endotracheal tube (ET). Patients aged 18 years or older who had been using an endotracheal tube for 48 hours were recruited. Tracheal secretions were collected; after extubation, the ETs were cut into two fragments in the infra-cuff region. One of these fragments was placed in a solution containing antibiotics and sent to the lab for culture and identification of yeasts. The remaining fragment was fixed and subjected to scanning electron microscopy (SEM). In total, 20 patients with an average age of 73.3 years (± 13.1) participated in this study. These patients remained under endotracheal intubation and invasive mechanical ventilation for an average of 6.4 (± 1.8) and 13.5 days (± 15), respectively. Of these patients, 45 % showed respiratory tract colonization by yeasts of the Candida genus, with C. albicans being the most frequently isolated species (66.7 %). Moreover, in almost 90 % of these patients, blastoconidia of the same yeast were found in the infra-cuff portion of the ET, as evidenced by SEM, strongly fixed on the ET surface. Yeasts isolated from both the infra-cuff region and the tracheobronchial secretions were susceptible to amphotericin B and fluconazole. In conclusion, our results show that the frequency of colonization by yeasts of the Candida genus in the tracheobronchial secretions of intubated patients within 48 hours is high, and that these species can also be found as a biofilm on the ET surface.

Effect of the introduction of C-MAC videolaryngoscopy on first-pass intubation success rates for emergency medicine registrars

OBJECTIVES

The present study investigated the impact of introducing C-MAC videolaryngoscopy as the standard method of visualising glottic structures on first-pass intubation success of emergency medicine (EM) registrars in a large tertiary academic hospital in New Zealand.

METHODS

In this retrospective cohort study, all patients receiving attempted orotracheal intubation in Auckland City Hospital ED 1 year prior to and 1 year after the introduction of C-MAC videolaryngoscopy were compared. The primary outcome was first-pass intubation success rates by EM registrars. Secondary outcomes were first-pass success rates by all intubators, and incidence of any complication of intubation.

RESULTS

There were 163 intubations by EM registrars from June 2015 to August 2017. There was a clinically important and statistically significant improvement in first-pass success from 59.2% (95% confidence interval [CI] 44.1-68.8%) to 85.1% (95% CI 76.0-91.2%, P < 0.001) after the introduction of C-MAC. In multivariate analysis, the independent predictors of success were: Airway Not Predicted Difficult, odds ratio (OR) 2.49 (95% CI 1.06-5.85, P = 0.037); and use of videolaryngoscope, OR 4.49 (95% CI 1.85-10.91, P = 0.001). Overall, complications of intubation improved significantly after introduction of C-MAC (28.9%, 95% CI 19.9-40.0% prior to C-MAC introduction; 16.1%, 95% CI 9.7-25.3% after; P = 0.048).

CONCLUSION

This is the first published study specifically addressing EM registrar intubation success rates in New Zealand, adding to the existing body of data suggesting that videolaryngoscopy may improve success rates for novice intubators.

Derivation and validation of a formula for paediatric tracheal tube size using bootstrap resampling procedure

BACKGROUND AND AIMS

The accuracy of age-, length- and weight-based formulae to predict optimal size of uncuffed tracheal tubes (TTs) in children varies widely. We determined the accuracy of age, length and weight in predicting the size of TT in Indian children, and derived and validated a formula using the best predictor.

METHODS

In the derivation phase, 100 children aged 1-8 years undergoing general anaesthesia and tracheal intubation with an uncuffed tube were prospectively studied. The correct size of the TT used was confirmed using the leak test. A bootstrap resampling procedure was used to estimate the accuracy of the predictors (age, weight, or length alone; length and age; length and weight; and length, weight and age). The best predictor was used to derive a formula (Paediatric Tube Size Predictor, PTSP) to calculate the size of TT. The accuracy of PTSP was tested in 150 children of the same age group in the validation phase.

RESULTS

Length (L (in meters), R 2 = 0.61) was the best single predictor of the size of TT and was used to derive the PTSP as internal diameter = 3L + 2.5. In the validation phase, the PTSP predicted the size of TT correctly in 75% of children. Re-intubation was associated with a higher incidence of respiratory morbidity than one-time tracheal intubation.

CONCLUSION

Length of the child predicts the size of an uncuffed TT better than age and weight. The PTSP formula based on length correctly predicts the size of uncuffed TT in 75% of children.

Apneic nasal oxygenation and safe apnea time during pediatric intubations by learners

BACKGROUND

Apneic nasal oxygenation (ApOx) prolongs the time to desaturation during intubation of adult patients, but there is limited prospective evidence for apneic oxygenation in pediatric patients.

AIMS

We hypothesized that ApOx during operating room intubation of pediatric patients by inexperienced learners would prolong the interval before desaturation.

METHODS

This prospective observational study compared intubation data for 196 pediatric surgical patients intubated by learners under baseline practice (no nasal cannula), to 160 patients enrolled after adoption of routine apneic nasal cannula oxygenation at 5 L/min. The primary outcome was elapsed time between anesthetic induction and pulse oximetry (SpO₂ ) falling to 95, if ever.

RESULTS

Nasal cannula oxygenation during intubation by learners delayed desaturation to SpO₂ 95 (risk ratio for this event before intubation 0.05, 95% CI 0.03-0.09; P < 0.0001).

CONCLUSIONS

Apneic oxygenation via nasal cannula during intubation of pediatric surgical patients prolongs time before desaturation, thus extending the safe interval for airway management by learners.

A prospective observational study of predictors of difficult intubation in Indian patients

Background and Aims:

During routine preoperative assessment of patients one of the commonest practices is predicting difficulty of intubation. The present study was undertaken to evaluate parameters associated with difficult intubation and to test on new set of patients. At the end, to form simple predictive rule to decreased the number of false alarms.

Material and Methods:

In initial series of 483 Indian population patients we measured age, sex, weight, height, interincisor gap, mandibular length, neck movement, neck circumference, subluxation of mandible, sternocricoid distance, and identified factors associated with difficult intubation. These were applied on next 480 patients of prospective series and simple predictive rule in form of risk sum score was developed.

Results:

After analyzing initial series data we found that weight (P = 0.033), height (P = 0.034), interincisor gap (P = 0.005), subluxation (P < 0.001), neck movement (P < 0.001), and sternocricoid distance (P = 0.020) were significantly associated with difficult intubation. These six factors were applied on next set of 480 patients to found accuracy of predicting difficult intubation of weight (51.7%), height (83.8%), interincisor gap (80.2%), subluxation (77.7%), neck movement (82.7%), and sternocricoid distance (79.2). Total score greater than 2 predicted 92.8% of difficult laryngoscopies correctly as against 33.9% would be falsely labeled as difficult.

Conclusion:

Interincisor gap and sternocricoid distance are the two most sensitive factors predicting difficult intubation in Indian patients. However, risk sum score of more than 6 may lead to better anticipation of truly difficult intubations.

A comparative randomized trial of intubation success in difficult intubation cases: the use of a Frova intubation catheter versus a Bonfils intubation fiberoscope

Introduction

A difficult airway is one of the main causes of morbidity and mortality in patients who undergo surgical interventions. Therefore, many devices and algorithms have been developed for the management of a difficult airway. However no study has been conducted comparing Frova catheter (FC) and a Bonfils fiberoscope (BF) to date.

Aim

To compare the effectiveness and success of two devices, a FC and BF, in difficult intubation cases.

Material and methods

Design: Single-centre randomized controlled trial in patients with difficult airways. The assignment order was created by unplanned number charts, and the assignment was hidden in closed covers, which were not unlocked until case permission had been provided. Setting: The trial was undertaken in a university hospital in Turkey. The primary analysis was based on 60 participants (n = 30, n = 30) with difficult intubation. The main outcomes were the success rates of placement of the tracheal tube in the trachea and the duration of the tracheal intubation process.

Results

In the BF group, successful intubation was carried out in 25 of the 30 (83.3%) patients, whereas intubation was successful in 28 of the 30 patients (93.3%) in the FC group. Patients who could not be intubated with the first device were intubated with the other device. The mean duration of intubation was 109 (85–140) s in the BF group, whereas it was 38.8 (26–60) s in the FC group.

Conclusions

Both devices were successful in difficult intubation cases. However, given the shorter duration of intubation using the FC and its lower cost as compared with that of the BF, the FC can be considered superior to the BF in difficult intubation cases.

MyD88 Is Required for Efficient Control of Coxiella burnetii Infection and Dissemination

The intracellular pathogen Coxiella (C.) burnetii causes Q fever, a usually self-limiting respiratory infection that becomes chronic and severe in some patients. Innate immune recognition of C. burnetii and its role in the decision between resolution and chronicity is not understood well. However, TLR2 is important for the response to C. burnetii in mice, and genetic polymorphisms in Myd88 have been associated with chronic Q fever in humans. Here, we have employed MyD88-deficient mice in infection models with the attenuated C. burnetii Nine Mile phase II strain (NMII). Myd88^−/− macrophages failed to restrict the growth of NMII in vitro, and to upregulate production of the cytokines TNF, IL-6, and IL-10. Following intraperitoneal infection, NMII bacterial burden was significantly higher on day 5 and 20 in organs of Myd88^−/− mice. After infection via the natural route by intratracheal injection, a higher bacterial load in the lung and increased dissemination of NMII to other organs was observed in MyD88-deficient mice. While wild-type mice essentially cleared NMII on day 27 after intratracheal infection, it was still readily detectable on day 42 in multiple organs in the absence of MyD88. Despite the elevated bacterial load, Myd88^−/− mice had less granulomatous inflammation and expressed significantly lower levels of chemoattractants, inflammatory cytokines, and of several IFNγ-induced genes relevant for control of intracellular pathogens. Together, our results show that MyD88-dependent signaling is essential for early control of C. burnetii replication and to prevent systemic spreading. The continued presence of NMII in the organs of Myd88^−/− mice constitutes a new mouse model to study determinants of chronicity and resolution in Q fever.

Emergency front of neck airway: What do trainers in the UK teach? A national survey

Background and Aims:

Front of neck airway (FONA) is the final step to deliver oxygen in the difficult airway management algorithms. The Difficult Airway Society 2015 guidelines have recommended a standardized scalpel cricothyroidotomy technique for an emergency FONA. There is a wide variability in the FONA techniques with disparate approaches and training. We conducted a national postal survey to evaluate current teaching, availability of equipment, experienced surgical help and prevalent attitudes in the face of a can’t intubate, can’t oxygenate situation.

Material and Methods:

The postal survey was addressed to airway leads across National Health Service hospitals in the United Kingdom (UK). In the anesthetic departments with no designated airway leads, the survey was addressed to the respective college tutors. A total of 259 survey questionnaires were posted.

Results:

We received 209 survey replies with an overall response rate of 81%. Although 75% of respondents preferred scalpel cricothyroidotomy, only 28% of the anesthetic departments considered in-house FONA training as mandatory for all grades of anesthetists. Scalpel-bougie-tube kits were available in 95% of the anesthetic departments, either solely or in combination with other FONA devices.

Conclusion:

The survey has demonstrated that a majority of the airway trainers in the UK would prefer scalpel cricothyroidotomy as emergency FONA. There is a significant variation and deficiency in the current levels of FONA training. Hence, it is important that emergency FONA training is standardized and imparted at a multidisciplinary level.

Risk Factors for and Prediction of Hypoxemia during Tracheal Intubation of Critically Ill Adults

RATIONALE

Hypoxemia is a common complication during tracheal intubation of critically ill adults and is a frequently used endpoint in airway management research. Identifying patients likely to experience low oxygen saturations during tracheal intubation may be useful for clinical practice and clinical trials.

OBJECTIVES

To identify risk factors for lower oxygen saturations and severe hypoxemia during tracheal intubation of critically ill adults and develop prediction models for lowest oxygen saturation and hypoxemia.

METHODS

Using data on 433 intubations from two randomized trials, we developed linear and logistic regression models to identify preprocedural risk factors for lower arterial oxygen saturations and severe hypoxemia between induction and 2 minutes after intubation. Penalized regression was used to develop prediction models for lowest oxygen saturation after induction and severe hypoxemia. A simplified six-point score was derived to predict severe hypoxemia.

RESULTS

Among the 433 intubations, 426 had complete data and were included in the model. The mean (standard deviation) lowest oxygen saturation was 88% (14%); median (interquartile range) was 93% (83-98%). Independent predictors of severe hypoxemia included hypoxemic respiratory failure as the indication for intubation (odds ratio [OR], 2.70; 95% confidence interval [CI], 1.58-4.60), lower oxygen saturation at induction (OR, 0.92 per 1% increase; 95% CI, 0.89-0.96 per 1% increase), younger age (OR, 0.97 per 1-year increase; 95% CI, 0.95-0.99 per 1-year increase), higher body mass index (OR, 1.03 per 1 kg/m2; 95% CI, 1.00-1.06 per 1 kg/m2), race (OR, 4.58 for white vs. black; 95% CI, 1.97-10.67; OR, 4.47 for other vs. black; 95% CI, 1.19-16.84), and operator with fewer than 100 prior intubations (OR, 2.83; 95% CI, 1.37-5.85). A six-point score using the identified risk factors predicted severe hypoxemia with an area under the receiver operating curve of 0.714 (95% CI, 0.653 to 0.778).

CONCLUSIONS

Lowest oxygen saturation and severe hypoxemia during tracheal intubation in the intensive care unit can be accurately predicted using routinely available preprocedure clinical data, with saturation at induction and hypoxemic respiratory failure being the strongest predictors. A simple bedside score may identify patients at risk for hypoxemia during intubation to help target preventative interventions and facilitate enrichment in clinical trials.

Postintubation Sequels: Influence of Fluticasone and Technique of Intra-Operative Muscle Relaxation

BACKGROUND

Postintubation sequels (PIS) are a cause of serious concern in the postoperative period.

AIM

The aim of this study is to find the influence of preoperative inhaled steroid and technique of muscle relaxation on PIS.

SETTINGS AND DESIGN

This prospective, exploratory pilot study was conducted on 120 adult American Society of Anesthesiologist physical status Class I and II patients undergoing general anesthesia (GA) with muscle relaxation and cuffed endotracheal tube (ETT) insertion.

PATIENTS AND METHODS

Patients were randomized into four groups as follows: intermittent muscle relaxation with preanesthetic inhalation of either distilled water puffs (Group ID) or fluticasone puffs (Group IF); continuous infusion of muscle relaxant with preanesthetic inhalation of either distilled water puffs (Group CD) or fluticasone puffs (Group CF). After induction of GA, ETT was inserted. The intra-cuff pressure was maintained constant. The trachea was extubated in the light plane in intermittent groups and in the deep plane in continuous groups.

STATISTICAL ANALYSIS

Qualitative parameters were compared using the Chi-square test and quantitative parameters using repeated measure ANOVA followed by Tukey's test.

RESULTS

Group CF had significantly less incidence of sore throat and hoarseness compared to groups ID and IF. The severity of sore throat was more in groups ID and IF than in groups CF and CD (P < 0.002). The severity of hoarseness was least in group CF (23.3%) and highest in group IF (90%). None of the patients had a cough in group CF. The incidence and severity of dysphagia were significantly less in group CF as compared to other groups (P < 0.005 and P < 0.008, respectively).

CONCLUSION

Continuous infusion of muscle relaxant with extubation in deep plane of anesthesia with preanesthetic inhalation of fluticasone puffs results in lesser incidence and severity of PIS.

Efficacy of dexmedetomidine versus remifentanil to blunt the hemodynamic response to laryngoscopy and orotracheal intubation: a randomized clinical trial

The study aims to compare the efficacy of dexmedetomidine (DEX) vs. remifentanil (REM) to blunt the hemodynamic response to laryngoscopy and orotracheal intubation. Enrolled in a double-blind clinical trial, 124 patients undergoing elective surgery under general anesthesia at Amirkabir Hospital (Arak, Iran), were assigned into four groups equally (31 patients in each group), DEX, REM, DEX-REM, and normal saline (NS), who received intravenous DEX (1 µg/kg), REM (1 µg/kg), their equal mixture (each 0.5 µg/kg, 1 minute before tracheal intubation), and NS, respectively. Then, blood pressure (BP), heart rate (HR), and arterial oxygen saturation (SaO₂) were measured on arrival to the operating room, 1 minute before laryngoscopy and tracheal intubation, immediately after intubation, and afterwards every 5 to 15 minutes, and finally the data were analyzed using SPSS 18.0. The groups were same regarding to age, sex and baseline hemodynamic variables including mean of BP (P = 0.157), HR (P = 0.105) and SaO₂ (P = 0.366). Tukey post-hoc test showed that there DEX, REM, and a DEX + REM groups was same regarding to MBP and HR, but these hemodynamic responses were higher in NS group than other groups at all time after laryngoscopy and intubation (P < 0.05). Moreover, repeated measure test showed a decreasing trend in MBP and HR in three intervention groups at all time after intubation (P > 0.05). A DEX/REM mixture had the lowest BP and three intervention groups had lower HR than the NS group. A mixture of the drugs used seems to lead to not only a prevented increase in HR and BP during laryngoscopy but also a decreased BP and HR. This study was registered in Iranian Registry Clinical Center with the registration No. IRCT2016092722254N1.

Acute Lung Injury in Response to Intratracheal Instillation of Lipopolysaccharide in an Animal Model of Emphysema Induced by Elastase

The response of lungs with emphysema to an acute lung injury (ALI) remains unclear. This study compared the lung response to intratracheal instillation of lipopolysaccharide (LPS) in rats with and without emphysema. Twenty-four Wistar rats were randomized to four groups: control group (C-G), ALI group (ALI-G), emphysema group (E-G), emphysema and ALI group (E-ALI-G). Euthanasia and the following analysis were performed 24 h after ALI induction: lung histology, bronchoalveolar lavage (BAL), mRNA expression of inflammatory mediators, and blood gas measures. The histological analysis showed that animals of ALI-G (0.55 ± 0.15) and E-ALI-G (0.69 ± 0.08) had a higher ALI score compared to C-G (0.12 ± 0.04) and E-G (0.16 ± 0.04) (p < 0.05). The analysis of each component of the score demonstrated that ALI-G and E-ALI-G had greater alveolar and interstitial neutrophil infiltration, as well as greater amount of alveolar proteinaceous debris. Comparing the two groups that received LPS, there was a trend of higher ALI in the E-ALI-G, specially due to a higher neutrophil infiltration in the alveolar spaces and a higher septal thickening. Total cell count (E-G = 3.09 ± 0.83; ALI-G = 4.45 ± 1.9; E-ALI-G = 5.9 ± 2.1; C-G = 0.73 ± 0.37 × 10⁵) and neutrophil count (E-G = 0.69 ± 0.35; ALI-G = 2.53 ± 1.09; E-ALI-G = 3.86 ± 1.4; C-G = 0.09 ± 0.07 × 10⁵) in the BAL were higher in the groups E-G, ALI-G, and E-ALI-G when compared to C-G (p < 0.05). The IL-6, TNF-α, and CXCL2 mRNA expressions were higher in the animals that received LPS (ALI-G and E-ALI-G) compared to the C-G and E-G (p < 0.05). No statistically significant difference was observed in the BAL cellularity and in the expression of inflammatory mediators between the ALI-G and the E-ALI-G. The severity of ALI in response to intratracheal instillation of LPS did not show difference in rats with and without intratracheal-induced emphysema.

Predictors of difficult videolaryngoscopy with GlideScope® or C-MAC® with D-blade: secondary analysis from a large comparative videolaryngoscopy trial

BACKGROUND

Tracheal intubation using acute-angle videolaryngoscopy achieves high success rates, but is not without difficulty. We aimed to determine predictors of 'difficult videolaryngoscopy'.

METHODS

We performed a secondary analysis of a data set (n=1100) gathered from a multicentre prospective randomized controlled trial of patients for whom difficult direct laryngoscopy was anticipated and who were intubated with one of two videolaryngoscopy devices (GlideScope(®) or C-MAC(®) with D-blade). 'Difficult videolaryngoscopy' was defined as 'first intubation time >60 s' or 'first attempt intubation failure'. A multivariate logistic regression model along with stepwise model selection techniques was performed to determine independent predictors of difficult videolaryngoscopy.

RESULTS

Of 1100 patients, 301 were identified as difficult videolaryngoscopies. By univariate analysis, head and neck position, provider, type of surgery, and mouth opening were associated with difficult videolaryngoscopy (P<0.05). According to the multivariate logistic regression model, characteristics associated with greater risk for difficult videolaryngoscopy were as follows: (i) head and neck position of 'supine sniffing' vs 'supine neutral' {odds ratio (OR) 1.63, 95% confidence interval (CI) [1.14, 2.31]}; (ii) undergoing otolaryngologic or cardiac surgery vs general surgery (OR 1.89, 95% CI [1.19, 3.01] and OR 6.13, 95% CI [1.85, 20.37], respectively); (iii) intubation performed by an attending anaesthestist vs a supervised resident (OR 1.83, 95% CI [1.14, 2.92]); and (iv) small mouth opening (OR 1.18, 95% CI [1.02, 1.36]).

CONCLUSION

This secondary analysis of an existing data set indicates four covariates associated with difficult acute-angle videolaryngoscopy, of which patient position and provider level are modifiable.

Mucosal injury following short-term tracheal intubation: A novel animal model and composite tracheal injury score

OBJECTIVES

Postintubation laryngotracheal injury is common. Assessment of histopathological changes currently requires animal models. We set about developing a viable, resource effective animal model to study these effects and to develop a detailed tissue injury score.

METHODS

Six pigs were anesthetized using a standard regimen. We intubated the tracheas using a standard endotracheal tube modified to include optical sensors. Animals were anesthetized for a duration of two to four hours, and their lungs were ventilated using a normoxic gas mixture. Following euthanasia, the tracheas were removed and underwent histological assessment by two independent veterinary pathologists. The histological lesions, including controls, were described and quantified, and two pathologists classified tissues according to a novel injury score.

RESULTS

Mean duration of tracheal intubation was 191 minutes (SD ± 41.6). In all except one animal, cuff pressures were maintained in the range of 25-45 cmH20. Histopathological findings in all study animals showed more extensive changes than previously described with short-term intubation. Changes were seen in all mucosal layers consistent with acute, suppurative, and ulcerative tracheitis. The range of scores of the developed composite scoring system among the animals was wider than in earlier descriptions. There was a high percentage of agreement between both pathologists.

CONCLUSIONS

We have described a novel tracheal injury score to assess pathological changes following short term intubation in a viable animal model. The scoring system distinguished between the test animals as well as controls and may be appropriate for continuing study of intubation injury.

LEVEL OF EVIDENCE

3.

Effect of intratracheal dexmedetomidine administration on recovery from general anaesthesia after gynaecological laparoscopic surgery: a randomised double-blinded study

OBJECTIVES

To examine the efficacy of intratracheal dexmedetomidine (Dex) injection for the prevention of the laryngeal response on emergence from general anaesthesia following gynaecological laparoscopic surgery.

DESIGN

Prospective, randomised, double-blinded, controlled trial.

SETTING

A general hospital, Guangdong Province, China.

PARTICIPANTS

All patients who underwent elective laparoscopic gynaecological surgery, aged 18-60 years old, 40-80 kg in weight, American Society of Anesthesiologists class I-II were eligible. Patients were excluded if they had respiratory disease, heart disorders which might represent risk factors of potential complications of Dex such as bradycardia, heart block, coronary heart disease, uncontrolled hypertension or the long-term use of sedative drugs.

INTERVENTION

Patients were randomly allocated to either receive intratracheal Dex (DT), intravenous Dex (DV) or intravenous saline (CON, n=30, respectively). In the DT and DV groups, Dex (0.5 µg/kg) was diluted and mixed in 1 or 20 mL of saline, respectively, and injected via the intratracheal or intravenous route 30 min before the completion of the surgery.

OUTCOME MEASURES

The primary outcome was the coughing extent among the three groups. Secondary outcomes included awareness time, extubation time, postoperative visual analogue scale and Steward recovery score.

RESULTS

Compared with the CON group, the extent of coughing was significantly reduced in both the DV group and the DT group. Furthermore, the mean time to awareness (13.4 (4.3) vs 8.8 (2.9), p<0.001) and the extubation time (14.3 (4.3) vs 8.4 (3.6), p<0.001) were reduced in the DT group. Patients in the DT group also experienced better early recovery quality and less pain than those in the CON group. Furthermore, intratracheal Dex administration contributed to improved stability in haemodynamics with no significant side effects.

CONCLUSIONS

Intratracheal Dex administration may avoid untoward laryngeal responses for patients emerging from general anaesthesia after gynaecological laparoscopy.

TRIAL REGISTRATION NUMBER

ChiCTR-IOR-15007611.

Cuffed endotracheal tubes in infants less than 3 kg: A retrospective cohort study

BACKGROUND

Cuffed endotracheal tubes are being increasingly used in infants; however, current evidence in the literature mostly includes infants ≥ 3-kg weight.

AIMS

The aim of this observational study was to compare the short-term outcomes with the use of Microcuff^® cuffed vs uncuffed endotracheal tubes in neonates < 3 kg.

METHODS

We performed a retrospective cohort study in a single-centre, tertiary children's hospital neonatal intensive care unit. The study included all infants < 3 kg receiving Microcuff^® cuffed endotracheal tubes over the period January 2015 to January 2016. Controls were all infants 2000-2999 g receiving an uncuffed endotracheal tube over the period September 2015 to January 2016.

RESULTS

Twenty-three patients < 3 kg were intubated with cuffed endotracheal tubes. All were inserted in the operating room. Of 23 patients, 14 (60.9%) patients had the cuff inflated in the operating room and none subsequently in the neonatal intensive care unit. The group receiving cuffed endotracheal tubes was compared with 23 patients with uncuffed endotracheal tubes. There was no difference in weight (median 2620 g vs 2590 g, diff in median = 10, 95% CI -120, 130) or duration of intubation (median 27 vs 44 hours, diff in median = 17, 95% CI -5, 46). However, there was a significant difference in gestational age (median 37 vs 35 weeks, diff in median = -1, 95% CI -2, 0) and age at intubation (median 6 vs 0 days, diff in median = -4, 95% CI -10, -1). There were no significant differences in the rates of: change of endotracheal tube to find correct size (0/23 vs 4/23, P = .109, OR = 0.13, 95% CI 0.01, 1.41); median ventilator leak reading (0% [IQR 0%-12%] vs 0% [IQR 0%-5.5%], P = .201, diff in median = 0, 95% CI -5.5, 0); unplanned extubations (0/23 vs 2/23; atelectasis (4/23 vs 0/23; endotracheal tube blockage (0/23 vs 0/23; pneumonia (0/23 vs 0/23; or postextubation stridor (1/23 vs 2/23).

CONCLUSION

This retrospective study with a small sample size found that Microcuff^® cuffed endotracheal tubes may be safe in neonates < 3 kg. Well-designed randomized controlled trials are needed to address this issue definitively.

Respiratory-digestive tract fistula: two-center retrospective observational study

Background Aerodigestive fistulae can be defined as abnormal communications between the gastrointestinal tract and the respiratory tract. Choking after meals, coughing, feeding difficulties, tachycardia, and persistent pneumonia are the main presentations. The aim of our study was to review our experience in the management of 27 cases of acquired aerodigestive fistulae of different types, levels, and management. Methods We conducted a retrospective observational study on 27 cases of fistulae between the respiratory and digestive tracts, which were managed in 2 hospitals in Saudi Arabia in the last 5 years. The patients comprised 16 females and 11 males, with a mean age of 29 years (range 17-67 years). Results The most common aerodigestive tract fistula was tracheoesophageal in 8 patients, followed by esophagobronchial in 6, and esophagopleural in 5. Four postendoscopic fistulae were included. The least common were gastropleural and esophagopulmonary fistulae. The most common etiologies were iatrogenic and esophageal cancer, and the least common was blunt chest trauma. The main presentations were fever, chocking after or during meals, and tachycardia. We used various modalities of treatment: conservative, cervical repair, thoracoabdominal repair, hybrid insertion of a T-tube, endoscopic esophageal stenting, and endoscopic clipping of the fistulous tract. During follow-up, 6 patients died due to advanced esophageal cancer in 5 and upper airway obstruction after iatrogenic tracheobronchial fistula in one. Conclusion Acquired aerodigestive fistula is a devastating condition that should be managed early and aggressively by a multidisciplinary team.

Systematic Assessment of Strategies for Lung-targeted Delivery of MicroRNA Mimics

There is considerable interest in the use of synthetic miRNA mimics (or inhibitors) as potential therapeutic agents in pulmonary vascular disease; however, the optimal delivery method to achieve high efficiency, selective lung targeting has not been determined. Here, we sought to investigate the relative merits of different lung-targeted strategies for delivering miRNA mimics in rats. Methods: Tissue levels of a synthetic miRNA mimic, cel-miR-39-3p (0.5 nmol in 50 µL invivofectamine/PBS vehicle) were compared in male rats (n=3 rats/method) after delivery by commonly used lung-targeting strategies including intratracheal liquid instillation (IT-L), intratracheal aerosolization with (IT-A^V) or without ventilator assistance (IT-A), intranasal liquid instillation (IN-L) and intranasal aerosolization (IN-A). Intravenous (IV; via jugular vein), intraperitoneal (IP) and subcutaneous (SC) delivery served as controls. Relative levels of cel-miR-39 were quantified by RT-qPCR. Results: At 2 h post delivery, IT-L showed the highest lung mimic level, which was significantly higher than levels achieved by all other methods (from ~10- to 10,000-fold, p<0.05). Mimic levels remained detectable in the lung 24 h after delivery, but were 10- to 100-fold lower. The intrapulmonary distribution of cel-miR-39 was comparable when delivered as either a liquid or aerosol, with evidence of mimic distribution to both the left and right lung lobes and penetration to distal regions. All lung-targeted strategies showed lung-selective mimic uptake, with mimic levels 10- to 100-fold lower in heart and 100- to 10,000-fold lower in liver, kidney and spleen. In contrast, IV, SC and IP routes showed comparable or higher mimic levels in non-pulmonary tissues. Conclusions: miRNA uptake in the lungs differed markedly by up to 4 orders of magnitude, demonstrating that the choice of delivery strategy could have a significant impact on potential therapeutic outcomes in preclinical investigations of miRNA-based drug candidates.

Effectiveness of tip rotation in fibreoptic bronchoscopy under different experimental conditions: an in vitro crossover study

Background

Proper manipulation of fibreoptic bronchoscopes is essential for successful tracheal intubation or diagnostic bronchoscopy. Failure of proper navigation and rotation of the fibrescope may lead to difficulties in advancing the fibrescope and might also be responsible for (unnecessary) difficulties and delays in fibreoptic tracheal intubation, with subsequent hypoxaemia. The present study, therefore, aimed to assess the effectiveness of tip rotation in flexible bronchoscopes in different experimental conditions.

Methods

Five differently sized pairs of fibrescopes (outer diameters of 2.2, 2.4, 3.5, 4.2, and 5.2 mm) were inserted into paediatric airway manikins via an appropriately sized laryngeal mask and were turned clockwise or anticlockwise at the fibrescope body or cord to 45, 90, and 180°, with the cord held either straight or bent. The primary outcome measure was the ratio of rotation measured at the tip over the rotation performed with the fibrescope body or cord.

Results

Overall, the 'body' turn was significantly less effective when a bent cord was present (mean difference ranging from 29.8% (95% confidence interval 8.8-50.9) to 117.4% (93.6-141.2). This difference was diminished when the 'cord' turn was performed. Smaller fibrescopes, with outer diameters of 2.2 and 2.4 mm, were inferior with respect to the transmission of 'body' rotation to the tip.

Conclusions

'Cord' turning of the fibrescope appears to be more effective in rotating the tip than a turn of the fibrescope 'body' only. Straightening the fibrescope cord and combined 'body' and 'cord' turning are recommended.

Loss of Surfacten® during bolus administration with a feeding catheter

BACKGROUND

Surfactant replacement therapy is widely used for treating neonatal respiratory distress syndrome, but insufficient evidence is available on the use of Surfacten® (S-TA). This study investigated the inadvertent loss of S-TA during instillation via feeding catheters with different bore sizes.

METHODS

In this bench-based study, we measured the weight of syringes and tubes before and after surfactant treatment using a high-accuracy balance, and determined the amount of S-TA lost in tubes. We injected 120 mg of S-TA suspended in 4 or 3 mL into tubes followed with or without air boluses. Experiments were performed in triplicate. Percent weight loss of S-TA in each tube was calculated with or without air boluses.

RESULTS

Percent weight loss of S-TA was significantly higher in larger-bore tubes (P < 0.01, overall ANOVA), and was significantly lower after air bolus flushing in 3 Fr, 4 Fr, and 5 Fr tubes (P < 0.005, respectively). The 3 mL S-TA suspensions had a significantly higher percent loss than the 4 mL S-TA suspensions when using 4 Fr and 5 Fr tubes, and the 5 Fr closed system (P < 0.05, respectively).

CONCLUSIONS

Routine air bolus flushing effectively reduces S-TA loss in tubes. The 3 mL S-TA suspensions appear to be more susceptible to inadvertent S-TA loss during instillation. Therefore, caution is warranted for this procedure.

Two Different Endotracheal Tube Securing Techniques: Fixing Bandage vs. Adhesive Tape

Introduction:

Emergency physicians should secure Endotracheal tubes (ETT) properly in order to prevent unplanned extubation (UE) and its complications. Despite various available endotracheal tube holders, using bandages or tape are still the most common methods used in this regards.

Objective:

This study aimed to compare adhesive tape (AT) versus fixing bandage (FB) method in terms of properly securing ETT.

Methods:

This was an observational longitudinal trial. All patients older than 15-years-old admitted to the ED who had indication for ETT insertion were eligible. Patients were randomly assigned to one of the two groups in which AT or FB was applied. All patients were observed thoroughly in the first 24 hours after intubation. Using a pre-prepared checklist, encountered UE rate and other data were recorded.

Results:

Seventy-two patients with the mean age of 55.98 18.39 years were finally evaluated of which 38 cases (52.8%) were male. In total, 12% of patients in our study experienced unplanned extubation. Less than 12% of the patients experienced complete UE; there was no statistically significant difference between the two groups (p = 0.24). Comparison of UE with age showed no significant difference (p = 0.89). Male patients experienced more UE, but this was not statistically significant (p = 0.44).

Conclusion:

It is likely that whether the AT method or FB was applied for securing the ETT in emergency departments, there was no significant difference in rates of unplanned extubation.

Neurotoxic effects of subchronic intratracheal Mn nanoparticle exposure alone and in combination with other welding fume metals in rats

Manganese (Mn) is a toxic heavy metal exposing workers in various occupational settings and causing, among others, nervous system damage. Metal fumes of welding, a typical source of Mn exposure, contain a complex mixture of metal oxides partly in nanoparticle form. As toxic effects of complex substances cannot be sufficiently understood by examining its components separately, general toxicity and functional neurotoxicity of a main pathogenic welding fume metal, Mn, was examined alone and combined with iron (Fe) and chromium (Cr), also frequently found in fumes. Oxide nanoparticles of Mn, Mn + Fe, Mn + Cr and the triple combination were applied, in aqueous suspension, to the trachea of young adult Wistar rats for 4 weeks. The decrease of body weight gain during treatment, caused by Mn, was counteracted by Fe, but not Cr. At the end of treatment, spontaneous and evoked cortical electrical activity was recorded. Mn caused a shift to higher frequencies, and lengthened evoked potential latency, which were also strongly diminished by co-application of Fe only. The interaction of the metals seen in body weight gain and cortical activity were not related to the measured blood and brain metal levels. Fe might have initiated protective, e.g. antioxidant, mechanisms with a more general effect.

Implementation of NAP4 emergency airway management recommendations in a quaternary-level pediatric hospital

Emergency airway management, particularly outside of the operating room, is associated with a high incidence of life-threatening adverse events. Based on the recommendations of the 4th National Audit Project, we aimed to develop hospital-wide systems changes to improve the safety of emergency airway management. We describe a framework for governance in the form of a hospital airway special interest group. We describe the development and implementation of the following systems changes: 1. A local intubation algorithm modified from the Difficult Airway Society's plan A-B-C-D approach, including clear pathways for airway escalation, and emphasizing the concepts of resuscitation prior to intubation, planning for failure, and avoidance of fixation error. 2. Simplified and standardized airway equipment located in identical airway carts in all critical care areas. 3. A preintubation checklist and equipment template to standardize preparation for airway management. 4. Availability of continuous waveform endtidal capnography in all critical care areas for confirmation of correct endotracheal tube placement. 5. Multidisciplinary team training to address the technical and nontechnical aspects of nonoperating room intubation. In addition, we describe methodology for ongoing monitoring of performance through a quality assurance framework. In conclusion, changes in the process of emergency airway management at a hospital level are feasible through collaboration. Their impact on patient-based outcomes requires further study.

Prediction of the mid-tracheal level using surface anatomical landmarks in adults: Clinical implication of endotracheal tube insertion depth

Endotracheal tube (ETT) should be placed at the optimal level to avoid single lung ventilation or accidental extubation. This study was performed to estimate the mid-tracheal level by using surface anatomical landmarks in adult patients.Neck computed tomography images of 329 adult patients between the ages of 16 and 79 years were reviewed. In the midline sagittal plane, the levels corresponding to the vocal cords, cricoid cartilage, suprasternal notch, manubriosternal junction, and carina were identified. The surface distances from the cricoid cartilage to the suprasternal notch (extCC-SSN) and that from the suprasternal notch to the manubriosternal junction (extSSN-MSJ) were measured. The relationship between mid-tracheal level and the surface distances was analyzed using Bland-Altman plot.The difference between the extCC-SSN and the mid-tracheal level was -6.6 (12.5) mm, and the difference between the extSSN-MSJ and the mid-tracheal level was -19.2 (6.1) mm. The difference between the extCC-SSN and the mid-tracheal level was smaller in females compared with males [-1.7 (11.7) mm vs -12.8 (10.7) mm; P < 0.001].The mid-tracheal level, which is helpful in planning the insertion depth of an ETT, can be predicted by the surface distance between the cricoid cartilage and suprasternal notch in adults, especially in females.

Screening Characteristics of Bedside Ultrasonography in Confirming Endotracheal Tube Placement; a Diagnostic Accuracy Study

INTRODUCTION

Confirmation of proper endotracheal tube placement is one of the most important and lifesaving issues of tracheal intubation. The present study was aimed to evaluate the accuracy of tracheal ultrasonography by emergency residents in this regard.

METHOD

This was a prospective, cross sectional study for evaluating the diagnostic accuracy of ultrasonography in endotracheal tube placement confirmation compared to a combination of 4 clinical confirmation methods of chest and epigastric auscultation, direct laryngoscopy, aspiration of the tube, and pulse oximetry (as reference test).

RESULTS

150 patients with the mean age of 58.52 ± 1.73 years were included (56.6% male). Sensitivity, specificity, positive predictive value, negative predictive value, and positive and negative likelihood ratio of tracheal ultrasonography in endotracheal tube confirmation were 96 (95% CI: 92-99), 88 (95% CI: 62-97), 98 (95% CI: 94-99), 78 (95% CI: 53-93), 64 (95% CI: 16-255), and 0.2 (95% CI: 0.1-0.6), respectively.

CONCLUSION

The present study showed that tracheal ultrasonography by trained emergency medicine residents had excellent sensitivity (>90%) and good specificity (80-90) for confirming endotracheal tube placement. Therefore, it seems that ultrasonography is a proper screening tool in determining endotracheal tube placement.

Effects of Lignocaine Administered Intravenously or Intratracheally on Airway and Hemodynamic Responses during Emergence and Extubation in Patients Undergoing Elective Craniotomies in Supine Position

INTRODUCTION

Sympathoadrenergic responses during emergence and extubation can lead to an increase in heart rate (HR) and blood pressure whereas increased airway responses may lead to coughing and laryngospasm. The aim of our study was to compare the effects of lignocaine administered intravenously (IV) or intratracheally on airway and hemodynamic responses during emergence and extubation in patients undergoing elective craniotomies.

METHODOLOGY

Sixty patients with physical status American Society of Anaesthesiologists Classes I and II aged 18-70 years, scheduled to undergo elective craniotomies were included. The patients were randomly divided into three groups of twenty patients; Group 1 receiving IV lignocaine and intratracheal placebo (IV group), Group 2 receiving intratracheal lignocaine and IV placebo (I/T group), and Group 3 receiving IV and intratracheal placebo (placebo group). The tolerance to the endotracheal tube was monitored, and number of episodes of cough was recorded during emergence and at the time of extubation. Hemodynamic parameters such as HR and blood pressure (systolic, diastolic, mean arterial pressure) were also recorded.

RESULTS

There was a decrease of HR in both IV and intratracheal groups in comparison with placebo group (P < 0.005). Rise in blood pressure (systolic blood pressure, diastolic blood pressure and mean arterial pressure) was comparable in both Groups 1 and 2 but was lower in comparison with placebo group (P < 0.005). Cough suppression was comparable in all the three groups. Grade III cough (15%) was documented only in placebo group.

CONCLUSION

Both IV and intratracheal lignocaine are effective in attenuation of hemodynamic response if given within 20 min from skull pin removal to extubation. There was comparable cough suppression through intratracheal route and IV routes than the placebo group.

A cohort evaluation of clinical use and performance characteristics of Ambu® AuraGain™: A prospective observational study

BACKGROUND AND AIMS

Ambu^® AuraGain™ (AG) (Ambu, Ballerup, Denmark) is a supraglottic device which has a design facilitating its use as a conduit for intubation. We designed this prospective observational study to assess the ease of AG placement in paralysed patients, determine its position and alignment to the glottis and assess its utility as a conduit for intubation.

METHODS

One hundred patients, aged 18-60 years, American Society of Anesthesiologists physical status I-II, undergoing elective surgery under general anaesthesia were included in the study. The ease and number of attempts for successful insertion, ease of gastric tube insertion, leak pressures, fibre-optic grade of view, number of attempts and time for tracheal intubation, time for AG removal and complications were recorded. The mean, standard deviation (SD), interquartile range (IQR) and range were calculated. The upper limit of confidence interval for overall failure rate was calculated using Wilson's score method.

RESULTS

AG was successfully inserted in all patients. The mean (SD) time taken for insertion was 17.32 (8.48) s. The median [IQR] leak pressures were 24 [20-28] cm of H₂O. Optimal laryngeal view for intubation was obtained in 68 patients. Eighty-eight patients could be intubated in the first attempt. Five patients could not be intubated. The overall failure rate of device was 9%.

CONCLUSION

AMBU^® AuraGain™ serves as an effective ventilating aid, but caution is suggested before using it as a conduit for endotracheal intubation.

Prediction of the midtracheal level based on external anatomical landmarks: implication of the optimal insertion depth of endotracheal tubes in pediatric patients

BACKGROUND

Optimal positioning of endotracheal tubes (ETTs) decreases the risk of accidental extubation or endobronchial intubation. This study evaluated the usefulness of external anatomical landmarks as practical references for determining an insertion depth of an ETT in pediatric patients.

METHODS

Computed tomography images of the necks of 183 pediatric patients (≤16 years of age) were reviewed. Levels corresponding to the vocal cords, cricoid cartilage, suprasternal notch, manubriosternal junction, and carina were identified on sagittal reconstructed images. The surface measurements from the cricoid cartilage to the suprasternal notch and that from the suprasternal notch to the manubriosternal junction were determined. Bland-Altman analysis was used to interpret the relationship between the midtracheal level and the surface measurements.

RESULTS

The difference between the midtracheal level and the surface distance from the cricoid cartilage to the suprasternal notch was 3.5 ± 7.0 mm, which was closer to zero than that between the midtracheal level and the surface distance from the suprasternal notch to the manubriosternal junction of 15.1 ± 6.1 mm.

CONCLUSION

The midtracheal level, helpful in planning the insertion depth of an ETT, can be predicted by measuring the surface distance from the cricoid cartilage to suprasternal notch in pediatric patients.

Performance of the PneuX System: A Bench Study Comparison With 4 Other Endotracheal Tube Cuffs

BACKGROUND

Cuff design affects microaspiration, a risk factor for pneumonia. We questioned whether the PneuX low-volume fold-free cuff design would prevent cuff leakage and maintain the same tracheal wall pressure as high-volume, low-pressure (HVLP) cuffs.

METHODS

We evaluated 4 HVLP-cuffed endotracheal tubes (ETTs), Hi-Lo (polyvinyl chloride [PVC]), Microcuff (polyurethane [PU]), SealGuard (PU + tapered), and TaperGuard (PVC + tapered), and the PneuX with its dedicated tracheal seal monitor. In Part 1, we determined tracheal wall pressure using each cuff's capacity to support water columns across recommended intracuff pressures. In Part 2, we evaluated the tracheal seal monitor function at recommended settings. In Part 3, we compared leakage volumes of all ETTs during 30 min of simulated mechanical ventilation or during 8 h if no leak occurred. Parts 1 and 3 were performed with/without lubrication and PEEP.

RESULTS

In Part 1, PneuX cuffs exerted an average tracheal wall pressure of 27.4 ± 2.4 cm H₂O at the recommended intracuff pressure of approximately 80 cm H₂O. Tracheal wall pressure did not differ among HVLP cuffs (19.6 ± 1.4 to 29.5 ± 1.4 cm H₂O). In Part 2, preinflation intracuff pressure affected the time to obtain tracheal seal monitor pressure attainment (P < .01). The tracheal seal monitor generated average calculated tracheal wall pressure of 33.4 ± 1.2 cm H₂O. In Part 3, PneuX ETT showed no leak across 8 h for all trials. Overall, leakage volume was lower with PU (P < .01) and PneuX (P < .01) than with PVC cuffs, regardless of shape, and lower with lubrication and/or PEEP (all P < .01). In each HVLP cuff, lubrication alone eliminated leak at an intracuff pressure of ≤30 cm H₂O.

CONCLUSIONS

The PneuX cuff generally exerted acceptable tracheal wall pressure, but the tracheal wall pressure monitor allowed pressures exceeding 30 cm H₂O in some trials and was the only ETT to prevent leak in all tests. For HVLP cuffs, leak was reduced by PU and PEEP and eliminated by lubrication.

Respirable controlled release polymeric colloid (RCRPC) of bosentan for the management of pulmonary hypertension: in vitro aerosolization, histological examination and in vivo pulmonary absorption

Bosentan is an endothelin receptor antagonist (ERA) prescribed for patients with pulmonary arterial hypertension (PAH). The oral delivery of bosentan possesses several drawbacks such as low bioavailability (about 50%), short duration of action, frequent administration, hepatotoxicity and systemic hypotension. The pulmonary administration would circumvent the pre-systemic metabolism thus improving the bioavailability and avoids the systemic adverse effects of oral bosentan. However, the short duration of action and the frequent administration are the major drawbacks of inhalation therapy. Thus, the aim of this work is to explore the potential of respirable controlled release polymeric colloid (RCRPC) for effective, safe and sustained pulmonary delivery of bosentan. Central composite design was adopted to study the influence of formulation and process variables on nanoparticles properties. The particle size, polydispersity index (PDI), entrapment efficiency (EE) and in vitro bosentan released were selected as dependent variables. The optimized RCRPC showed particle size of 420 nm, PDI of 0.39, EE of 60.5% and sustained release pattern where only 31.0% was released after 16 h. The in vitro nebulization of RCRPC indicated that PLGA nanoparticles could be incorporated into respirable nebulized droplets better than drug solution. Pharmacokinetics and histopathological examination were determined after intratracheal administration of the developed RCRPC to male albino rats compared to the oral bosentan suspension. Results revealed the great improvement of bioavailability (12.71 folds) and sustained vasodilation effect on the pulmonary blood vessels (more than 12 h). Bosentan-loaded RCRPC administered via the pulmonary route may therefore constitute an advance in the management of PAH.

Prehospital Endotracheal Intubation in Warm Climates: Caution is Required

BACKGROUND

Out-of-hospital endotracheal intubation is a frequent procedure for trauma care. Nevertheless, in warm climates, sunlight and heat can interfere with the flow of the usual procedure. They can affect the equipment and hinder the operator. There are few data on this issue. The presentation of this case highlights three common complications that may occur when intubating under a hot and bright sun.

CASE REPORT

A 23-year-old man had a car accident in Djibouti, at 11:00 a.m., in broad sunlight. The heat was scorching. Due to a severe head trauma, with a Glasgow Coma Scale score of 8, it was decided to perform an endotracheal intubation. The operator faced three problems: the difficulty of seeing inside the mouth in the bright sunlight, the softening of the tube under the influence of the heat, and the inefficiency of colorimetric CO2 detectors in the warm atmosphere in confirming the proper endotracheal tube placement. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Solutions are simple, but must be known and planned ahead, prior to beginning the procedure: Putting a jacket over his head while doing the laryngoscopy would solve the problem of dazzle; adjuncts like a stylet or gum elastic bougie have to be used at the outset to fix the softening problem; alternative methods to exhaled CO2 detection, such as the syringe aspiration technique, to confirm the proper tube placement, should be available.

A comparison of the Truview PCD and the GlideScope Cobalt AVL video-laryngoscopes to the Miller blade for successfully intubating manikins simulating normal and difficult pediatric airways

BACKGROUND

Video-laryngoscopes provide better glottic visualization, but tracheal intubation times are longer, compared to conventional direct laryngoscopy in adult patients with normal airways. The objective of this randomized crossover study was to compare times to successful tracheal intubation with video-laryngoscope and direct laryngoscopy in manikins simulating infants with normal and abnormal airways.

METHODS

Thirty experienced pediatric anesthesia practitioners performed tracheal intubation in three distinct manikins simulating infants with (i) a normal airway (ii), an anterior larynx, and (iii) the Pierre Robin sequence anatomy. These were performed using a standard Miller #1 blade, the GlideScope Cobalt AVL, and the Truview PCD video-laryngoscope, first in a normal neck and then an unstable cervical spine scenario (18 intubations/subject). The specific assigned order of devices and manikins for each participant was based on a three by three Latin square design to minimize carryover effects between the model and the device. Predefined times to intubation were analyzed by Cox regression model and Kaplan-Meier survival curves.

RESULTS

Intubation times were shorter and success rates were higher with the Miller blade compared to either the GlideScope or the Truview videoscope in all three manikins in both scenarios, but did not differ between the GlideScope and the Truview devices. Improved intubation times and success rates in the unstable cervical spine scenario compared to the normal neck were attributed to learning effects with sequential intubation.

CONCLUSION

Higher success rates and shorter intubation times with the Miller blade compared to either video-laryngoscope may reflect greater experience with direct laryngoscopy, need for more video-laryngoscopy training, or result from the manikin design. Individual practitioners may differ in their preference of device for intubating a child with anticipated difficult airway based on their previous experiences, self-assessment of their skills, and evaluation of the child's airway anatomy.

Learning and performance of endotracheal intubation by paramedical students: Comparison of GlideScope(®) and intubating laryngeal mask airway with direct laryngoscopy in manikins

Background and Aims:

GlideScope video laryngoscope (GVL) and intubating laryngeal mask airway (I-LMA) may be used to facilitate intubation and secure the airway in patients with normal and abnormal airways. The aim of this study was to evaluate whether (GVL) and (I-LMA) facilitate and improve the tracheal intubation success rate and could be learned and performed easily by paramedic students when compared with Macintosh direct laryngoscopy (DL).

Methods:

This study was a prospective, randomised crossover trial that included 100 paramedic students. Macintosh DL, I-LMA and GVL were tested in both normal and difficult airway scenarios. Each participant was allowed up to three intubation attempts with each device, in each scenario. The time required to perform tracheal intubation, the success rate, number of intubation attempts and of optimisation manoeuvres and the severity of dental trauma were recorded. Statistical analysis was performed using Chi-square, one-way ANOVA, or Kruskal-Wallis test as appropriate, followed by post hoc test.

Results:

GVL and I-LMA required less time to successfully perform tracheal intubation, showed a greater success rate of intubation, reduced the number of intubation attempts and optimization manoeuvres required and reduced the severity of dental trauma compared to Macintosh DL in both normal and difficult airway scenarios.

Conclusion:

GVL and I-LMA provide better airway management than Macintosh DL in both normal and difficult airway scenarios.

Strong protection against ricin challenge induced by a novel modified ricin A-chain protein in mouse model

Ricin toxin (RT) is an extremely potent toxin derived from the castor bean plant. As a possible bioterrorist weapon, it was categorized as a level B agent in international society. With the growing awareness and concerns of the “white powder incident” in recent years, it is indispensable to develop an effective countermeasure against RT intoxication. In this study we used site-directed mutagenesis and polymerase chain reaction (PCR) techniques to modify the gene of ricin A-chain (RTA). As a result, we have generated a mutated and truncated ricin A-chain (mtRTA) vaccine antigen by E.coli strain. The cytotoxicity assay was used to evaluate the safety of the as-prepared mtRTA antigen, and the results showed that there was no residual toxicity observed when compared to the recombinant RTA (rRTA) or native RT. Furthermore, BALB/c mice were subcutaneously (s.c.) vaccinated with mtRTA 3 times at an interval of 2 weeks, and then the survivals were evaluated after intraperitoneal (i.p.) or intratracheal challenge of RT. The vaccinated mice developed a strong protective immune response that was wholly protective against 40 × LD₅₀ of RT i.p. injection or 20 × LD₅₀ of RT intratracheal spraying. The mtRTA antigen has great potential to be a vaccine candidate for future application in humans.

Comparison of Airway Management Methods in Entrapped Patients: A Manikin Study

INTRODUCTION

Endotracheal intubation remains one of the most challenging skills in prehospital care. There is a minimal amount of data on the optimal technique to use when managing the airway of an entrapped patient. We hypothesized that use of a blindly placed device would result in both the shortest time to airway management and highest success rate.

METHODS

A difficult airway manikin was placed in a cervical collar and secured upside down in an overturned vehicle. Experienced paramedics and prehospital registered nurses used four different methods to secure the airway: direct laryngoscopy, digital intubation, King LT-D, and CMAC video laryngoscopy. Each participant was given three opportunities to secure the airway using each technique in random order. A study investigator timed each attempt and confirmed successful placement, which was determined upon inflation of the manikin's lungs. Intubation success rates were analyzed using a general estimating equations model to account for repeated measures and a linear mixed effects model for average time.

RESULTS

Twenty-two prehospital providers participated in the study. The one-pass success rate for the King LT-D was significantly higher than direct laryngoscopy (OR 0.048, CI 0.006-0.351, p < 0.01) and digital intubation (OR 0.040, CI 0.005-0.297, p < 0.01). However, there was no statistical difference between the one-pass success rate of the King LT-D and CMAC video laryngoscopy (OR 0.302, 95% CI 0.026-3.44, p = 0.33). The one-pass median placement time of the King LT-D (22 seconds, IQR 17-26) was significantly lower (p < 0.001) than direct laryngoscopy (60 seconds, IQR 42-75), digital intubation (38 seconds, IQR 26-74), and the CMAC (51 seconds, IQR 43-76).

CONCLUSIONS

In this study, while the King LT-D offered the quickest airway placement, success rates were not significantly greater than intubation using the CMAC video laryngoscope. Intubation using direct laryngoscopy and digital intubation were less successful and took more time. Use of a blindly placed device or a video laryngoscope may provide the best avenues for airway management of entrapped patients.

Anaesthetic management of acute airway obstruction

The acutely obstructed airway is a medical emergency that can potentially result in serious morbidity and mortality. Apart from the latest advancements in anaesthetic techniques, equipment and drugs, publications relevant to our topic, including the United Kingdom's 4th National Audit Project on major airway complications in 2011 and the updated American Society of Anesthesiologists' difficult airway algorithm of 2013, have recently been published. The former contained many reports of adverse events associated with the management of acute airway obstruction. By analysing the data and concepts from these two publications, this review article provides an update on management techniques for the acutely obstructed airway. We discuss the principles and factors relevant to the decision-making process in formulating a logical management plan.

The practice of intensive care nurses using the closed suctioning system: An observational study

Background:

Endotracheal suctioning (ETS) is an essential procedure performed for mechanically ventilated patients. ETS can be either performed by open or closed suctioning system (CSS). There may be some concern on how closed-system ETS is practiced by intensive care nurses. This study was designed to investigate closed-system ETS practices of critical care nurses and to compare their practice with standard recommendations.

Materials and Methods:

A prospective observational study was conducted during August and December 2012 to establish how critical care nurses (N = 40) perform different steps in a typical ETS practice and to compare it with the current best practice recommendations through a 23-item structured checklist. The results were categorized into three sections: Pre-suctioning, suctioning, and post-suctioning practices.

Results:

Pre-suctioning, suctioning, and post-suctioning practices mean scores were 7.5, 11.75, and 8.5, respectively, out of 16, 16, and 12, respectively. The total suctioning practice score was 27.75 out of 44. Most discrepancies were observed in the patients’ assessment and preparation, infection control practices, and use of an appropriate catheter. Spearman correlation coefficient indicated a significant statistical positive correlation between suctioning education period and suctioning practice score (P < 0.0001) and between working experience and suctioning practice score (P = 0.02).

Conclusions:

The findings revealed that critical care nurses do not fully adhere to the best practice recommendation in CSS. We recommend that standard guidelines on ETS practice be included in the current education of critical care nurses.

Laryngoscope Illuminance in a Tertiary Care Medical Center: Industry Standards and Implications for Quality Laryngoscopy

OBJECTIVE

To test the hypothesis that a substantial proportion of laryngoscopes exhibit substandard illuminance by comparing laryngoscope illuminance in a tertiary-level medical center to established standards and identifying features associated with poor illuminance.

STUDY DESIGN

Cross-sectional observational study.

SETTING

Academic tertiary care medical center (level 1 trauma center, specialty cardiac hospital, and general hospital).

SUBJECTS AND METHODS

Laryngoscopes from main, cardiac, and outpatient operating rooms; emergency department; and code carts were tested using a standard technique. Illuminance (lux) was chosen as the outcome measure. Benchmarks were derived from the International Standards Organization and medical literature. Light types included incandescent bulb, light-emitting diode, and xenon. Personnel were surveyed regarding maintenance practices.

RESULTS

Across all hospitals, 691 laryngoscopes were tested. Mean (SD) illuminance was 810 (700) lux for incandescent bulb-on-blade designs (n = 237), 1860 (1220) lux for incandescent bulb in-handle designs (n = 79), 4730 (3210) lux for LED (n = 354), and 28,800 (34,500) lux for xenon (n = 21). Seven percent of units failed to turn on (n = 45). Using an established threshold of 867 lux, 28% of devices (47% of incandescent, 12% of LED, and 10% of xenon) were substandard. All laryngoscopes were cleaned according to standard protocols following use; no preventive maintenance was reported.

CONCLUSION

Twenty-eight percent of laryngoscopes in a tertiary care hospital exhibit substandard illuminance; these results corroborate the findings of our inaugural study on this subject. Consequently, our hospital is instituting changes to reduce the likelihood of substandard performance by laryngoscopes in circulation.

Development of a guideline for the management of the unanticipated difficult airway in pediatric practice

BACKGROUND

Most airway problems in children are identified in advance; however, unanticipated difficulties can arise and may result in serious complications. Training for these sporadic events can be difficult. We identified the need for a structured guideline to improve clinical decision making in the acute situation and also to provide a guide for teaching.

OBJECTIVE

Guidelines for airway management in adults are widely used; however, none have been previously devised for national use in children. We aimed to develop guidelines for the management of the unanticipated difficult pediatric airway for use by anesthetists working in the nonspecialist pediatric setting.

METHOD

We reviewed available guidelines used in individual hospitals. We also reviewed research into airway management in children and graded papers for the level of evidence according to agreed criteria. A Delphi panel comprising 27 independent consultant anesthetists considered the steps of the acute airway management guidelines to reach consensus on the best interventions to use and the order in which to use them. If following the literature review and Delphi feedback, there was insufficient evidence or lack of consensus, regarding inclusion of a particular point; this was reviewed by a Second Specialist Group comprising 10 pediatric anesthetists.

RESULTS

Using the Delphi group's deliberations and feedback from the Second Specialist Group, we developed three guidelines for the acute airway management of children aged 1-8 years.

CONCLUSIONS

This paper provides the background, available evidence base, and justification for each step in the resultant guidelines and gives a rationale for their use.

Supraglottic airway devices

Supraglottic airway devices (SADs) are used to keep the upper airway open to provide unobstructed ventilation. Early (first-generation) SADs rapidly replaced endotracheal intubation and face masks in > 40% of general anesthesia cases due to their versatility and ease of use. Second-generation devices have further improved efficacy and utility by incorporating design changes. Individual second-generation SADs have allowed more dependable positive-pressure ventilation, are made of disposable materials, have integrated bite blocks, are better able to act as conduits for tracheal tube placement, and have reduced risk of pulmonary aspiration of gastric contents. SADs now provide successful rescue ventilation in > 90% of patients in whom mask ventilation or tracheal intubation is found to be impossible. However, some concerns with these devices remain, including failing to adequately ventilate, causing airway damage, and increasing the likelihood of pulmonary aspiration of gastric contents. Careful patient selection and excellent technical skills are necessary for successful use of these devices.

The pathogenesis of bleomycin-induced lung injury in animals and its applicability to human idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a devastating disease of unknown etiology, for which there is no curative pharmacological therapy. Bleomycin, an anti-neoplastic agent that causes lung fibrosis in human patients has been used extensively in rodent models to mimic IPF. In this review, we compare the pathogenesis and histological features of human IPF and bleomycin-induced pulmonary fibrosis (BPF) induced in rodents by intratracheal delivery. We discuss the current understanding of IPF and BPF disease development, from the contribution of alveolar epithelial cells and inflammation to the role of fibroblasts and cytokines, and draw conclusions about what we have learned from the intratracheal bleomycin model of lung fibrosis.