Tracheal intubation with videolaryngoscopes in patients with cervical spine immobilization: a randomized trial of the Airway Scope and the GlideScope.

BACKGROUND: The GlideScope (Verathon Inc., Bothell, WA, USA) and Airway Scope (Hoya Corp., Tokyo, Japan) have both been used for difficult airway management, including in patients with cervical spine pathology. The Airway Scope's disposable blade has a tube channel to guide tracheal tube insertion through the glottis. Our hypothesis is that this tube guidance system improves the ease of tracheal intubation compared with the GlideScope, which does not have a tube guiding system. We tested this hypothesis in a randomized comparison of the two videolaryngoscopes in patients whose cervical spines were immobilized. METHODS: Seventy consenting patients were randomized to have tracheal intubation with the GlideScope (n=35) or the Airway Scope (n=35). In all patients, we applied manual in-line stabilization of the cervical spine throughout airway management. All the airway procedures were carried out by two anaesthetists experienced in the use of both videolaryngoscopes. RESULTS: The tracheal intubation time was 34.2 (sd 25.1) s with the Airway Scope compared with 71.9 (47.9) s with the GlideScope (P<0.001). Tracheal intubation was successful with the Airway Scope in 35 (100%) patients compared with 31 (88.6%) patients with the GlideScope (P=0.114). Tracheal intubation was successful within 60 s in 33 (94.3%) patients with the Airway Scope and 22 (62.9%) patients with the GlideScope (P=0.003). CONCLUSIONS: These results suggest that the Airway Scope's tube guide system enables more rapid tracheal intubation compared with the GlideScope in patients with cervical spine immobilization.

The impact of manual in-line stabilisation on ventilation and visualisation of the glottis with the LMA CTrach: a randomised crossover trial.

The LMA CTrach (CTrach) enables ventilation, glottis visualisation and tracheal intubation via a laryngeal mask conduit. The CTrach has been successfully used in patients with cervical spine pathology, but it is unclear if cervical spine immobilisation affects its ease of use. In this randomised crossover trial, the CTrach was used once with and once without manual in-line stabilisation of the cervical spine in every patient. With manual in-line stabilisation, the median [IQR] time to achieve ventilation was 22 [16-32] s, compared with 19 [13-30] s without stabilisation (p = 0.065). With manual in-line stabilisation, the time to achieving a glottic views was 42 [30-63] s compared with 39 [25-53] s without stabilisation (p = 0.019). There was no difference in the success rates of achieving ventilation and glottic views. These results suggest that manual in-line stabilisation does not affect use of the CTrach.

Ease of intubation with the GlideScope or Airway Scope by novice operators in simulated easy and difficult airways--a manikin study.

The GlideScope and Airway Scope are video laryngoscopes that have been found to be useful in difficult airway situations. With the GlideScope, there are frequently problems associated with insertion of the tracheal tube despite the ability to view the glottis. The Airway Scope's imaging system and disposable PBlade aid alignment of the PBlade with the glottis and guide insertion of the tracheal tube. We performed a randomised crossover study of 20 medical students using both videolaryngoscopes in a manikin, with simulated normal and difficult airway scenarios. We found that the students required less time for tracheal intubation with the Airway Scope and reported greater ease of intubation with the Airway Scope in both scenarios. A greater number of students chose the Airway Scope as their device of choice. Our results suggest that the Airway Scope's features may improve the ease of tracheal intubation compared with the GlideScope.

Nocistatin attenuated the nociceptin induced c-Fos expression in the mouse hippocampus.

Nocistatin and nociceptin/orphaninFQ (N/OFQ) are the two new peptides which may have roles in nociception, memory, anxiety, and other biological functions. Nocistatin acts as a functional antagonist to N/OFQ in several functions, but their neuro-anatomical sites of interaction are unknown. We investigated the effect of combined intracerebroventricular (i.c.v.) injection of nocistatin with N/OFQ, on N/OFQ induced c-Fos expression in the mouse hippocampus, using c-Fos immunohistochemistry. We found that co-injection of nocistatin with N/OFQ significantly attenuated N/OFQ induced c-Fos expression in the hippocampus.

The teaching of anaesthesia in Singapore.

This article describes the development of undergraduate and postgraduate anaesthesia teaching and training in Singapore. Anaesthesia teaching has evolved from art and apprenticeship to become systematic, scientific and evidence-based, while retaining an emphasis on hands-on practical training. Simulator training provides unique advantages, which the University Department of Anaesthesia has utilised in integrated medical student teaching.

Nitrous oxide does not improve sevoflurane induction of anesthesia in adults.

STUDY OBJECTIVE: To compare the characteristics of sevoflurane induction with and without the addition of nitrous oxide (N(2)O) using tidal breathing inhalation induction without priming of the breathing circuit. DESIGN: Randomized, double-blind study. SETTING: Operating rooms of an ambulatory surgery suite at a university hospital. PATIENTS: 60 ASA physical status I and II adult patients undergoing elective surgery. INTERVENTIONS: Patients were randomized into two groups. During induction, Group 1 received 8% sevoflurane in N(2)O 4L/min and oxygen (O(2)) 2L/min; Group 2 received 8% sevoflurane in O(2) 6L/min. The time to cessation of finger tapping was used as the main index for induction time. Any adverse effects such as coughing, apnea, excessive oral secretions, laryngospasm, excitatory movements, and hemodynamic changes were also noted. MEASUREMENTS AND MAIN RESULTS: There were no significant differences in the induction times (Group 1: 62.0 vs. Group 2: 60.0 sec), number of breaths taken to this time (15.0 vs. 14.0), expired sevoflurane concentration at this time (3.4 vs. 3.2%), and time to Laryngeal Mask Airway insertion (160.0 vs. 195.0 sec). The frequencies of induction-related adverse events were similar in both study groups. CONCLUSION: The addition of N(2)O does not confer any clinically significant advantage in this method of sevoflurane induction in adults.

The usefulness of routine preoperative chest X-rays and ECGs: a prospective audit.

INTRODUCTION: Pre-operative Chest X-ray (CXR) and electrocardiograms (ECG) are routinely ordered locally for patients above a certain age. This study examines the usefulness of such a practice and its clinical impact. METHODS: Prospective audit of 875 consecutive anaesthetic patients over a one-month period, assessing the proportion and impact of abnormal CXR or ECG findings. RESULTS: The proportion of patients with abnormal CXR or ECG increased with worsening ASA status. There was little impact of routine pre-operative CXR and ECG on anaesthetic management. Only 11/324 CXR and 13/375 ECG affected anaesthetic technique or choice of therapeutic procedure. CONCLUSION: Targeted investigations should be performed as indicated by clinical findings rather than on the basis of arbitrary age cut-offs.

An evaluation of the laryngeal mask airway supreme' in 100 patients.

The Laryngeal Mask Airway (LMA) Supreme is a new supraglottic airway incorporating features of the LMA Proseal, LMA Fastrach and LMA Unique. We evaluated the LMA Supreme in 100 patients with normal airways having elective surgery. Our success rates of insertion and ventilation were 96% at the first attempt and 100% after two attempts. The median time to successful placement was 15 seconds (interquartile range 12 to 18 seconds). Forty-five patients breathed spontaneously and 55 patients had controlled ventilation. The incidence of blood staining on removal was 7% and 7% of patients had mild sore throat one hour postoperatively. One patient who had been placed in the left lateral position during surgery had left lingual nerve palsy postoperatively, which recovered completely after one month. Our findings suggest that in patients with normal airways, the LMA Supreme is easy to insert and provides a satisfactory airway with adequate seal pressures for ventilation.

Cricoid pressure prevents placement of the laryngeal tube and laryngeal tube-suction II.

BACKGROUND: The laryngeal tube has a potential role in patients with a difficult airway, but cricoid pressure is required if the patient is at risk of aspiration. The effect of cricoid pressure on insertion of these devices is unknown. METHODS: In a randomized cross-over study, the laryngeal tube (25 patients) or the laryngeal tube-suction II (15 patients) was inserted with cricoid pressure applied on one occasion and with sham pressure on the other occasion. Adequacy of ventilation, time to achieve adequate ventilation, and the leak pressure were assessed. RESULTS: Ventilation was adequate in all patients when sham pressure was applied. Cricoid pressure significantly reduced the rate of adequate ventilation to 6 of 25 patients for the laryngeal tube [P < 0.001; 95% confidence interval (CI) for difference: 59-93%] and to 5 of 15 patients for the laryngeal tube-suction II (P < 0.05; 95% CI for difference: 43-91%). The median time taken to achieve adequate ventilation for the laryngeal tube was 10 s [inter-quartile range (IQR): 8-15] (range 5-26) for sham pressure and 25 s (15-32) (15-33) for cricoid pressure; the median leak pressure was 30 (IQR: 30-30) (range 20-30) cm H2O for sham pressure and 15.5 (14.3-20.5) (12-22) cm H2O for cricoid pressure. CONCLUSIONS: Continuous cricoid pressure prevents correct placement of the laryngeal tube and the laryngeal tube-suction II such that placement and ventilation via these devices are ineffective. The effect of cricoid pressure on ventilation via these devices, after correct placement, remains unknown.

The accuracy of surrogate decisions in intensive care scenarios.

Critically ill patients are often unable to make decisions about life-sustaining treatments and surrogate decision-makers are relied upon. However, it is unclear how accurately the surrogates' decisions reflect patients' intentions and expectations. We interviewed 36 pairs of patients and their appointed surrogate decision-makers about their decisions regarding nine treatments in each of three scenarios. The scenarios were persistent vegetative state, coma with likely neurological damage and chronic disease with dementia. The patients were interviewed 24 hours after they had undergone elective surgery under general anaesthesia. The surrogates were interviewed separately by the same interviewer. There was poor agreement between decisions made by the patients and their surrogates. The patients' and surrogates' summary scores (median (interquartile range) [range]) for treatments were 0 (0-4) [0-9] vs 8 (0-9) [0-9] for the vegetative state scenario, 3 (0-9) [0-9] vs 9 (0-9) [0-9] for the coma scenario and 3 (0-9) [0-9] vs 9 (4-9) [0-9] for the chronic disease scenario. The significantly higher surrogate scores suggest that the surrogates' decisions would have resulted in the patients having far more treatment than the patients would have wanted. In our participants, there was poor agreement between the decisions made by surrogates and patients. Further study is needed on measures such as facilitated discussions, advance directives and the difficulties that surrogates face, in order to improve the accuracy of surrogates' decisions and respect of patients' autonomy.

The LMA CTrach, a new laryngeal mask airway for endotracheal intubation under vision: evaluation in 100 patients.

BACKGROUND: The LMA CTrach is a new laryngeal mask system consisting of an LMA CTrach Airway with integrated fibreoptic channels, and a detachable LMA CTrach Viewer. This system enables viewing of the larynx and aids endotracheal intubation through a laryngeal mask airway. Method. We used and evaluated this system in 100 adult patients undergoing general anaesthesia for elective surgery. Our primary outcomes were the success rates of LMA CTrach Airway insertion and endotracheal intubation with this system. RESULTS: We were able to insert the LMA CTrach Airway in and to ventilate all 100 patients. We were successful in endotracheal intubation, either under vision or blind, in 96 patients. We were able to view the larynx in 84 patients, but the quality of the best view obtained was very variable. The median (inter quartile range) time for the complete intubation process was 166 (114-233) s. The system allowed nearly continuous ventilation and oxygenation during the process. CONCLUSIONS: The LMA CTrach system has potential advantages over the LMA Fastrach system, including the ability to align the LMA outlet with the larynx and a high first intubation attempt success rate. However, it was difficult to view the larynx with the LMA CTrach compared with direct laryngoscopy, and expectations must be moderated.

An evaluation of poor LMA CTrach views with a fibreoptic laryngoscope and the effectiveness of corrective measures.

BACKGROUND: The LMA CTrach++ system has integrated fibreoptics to enable viewing of the glottis to aid tracheal intubation via a laryngeal mask conduit. Earlier evaluations of this system had shown high success rates of insertion, ventilation and tracheal intubation, but frequent difficulty or failure to view the glottis. METHOD: We evaluated CTrach views in 100 patients. In 69 patients with partial or no views of the glottis, we evaluated the causes with the aid of an Olympus LF-DP fibreoptic laryngoscope passed through the CTrach. In those with poor views, we tested the effectiveness of simple corrective measures to improve the views and optimize CTrach placement. These included pushing the CTrach deeper in, partial withdrawal by 6 cm and reinsertion to correct epiglottic downfolding, withdrawal by 1 cm and applying forward lift to correct obstruction by the arytenoids, and complete removal to clean the fibreoptic ports followed by reinsertion when secretions were the problem. RESULTS: Downfolding of the epiglottis caused poor views in 57 patients, which was correctable in 51. Obstruction of the view by the arytenoids occurred in seven patients and by secretions in five, all of which were correctable. With the Ctrach, we were able to ventilate the lungs in all patients, view the glottis in 94 and intubate the trachea in 97 patients. CONCLUSION: Despite the ability to ventilate the lungs in all patients with the CTrach, poor initial views were very frequent, indicating suboptimal placement, although most poor views can be improved, leading to a high intubation success rate.

Evaluation of ease of intubation with the GlideScope or Macintosh laryngoscope by anaesthetists in simulated easy and difficult laryngoscopy.

The GlideScope is a new video laryngoscope developed for management of the difficult airway. We compared the GlideScope with the Macintosh laryngoscope in simulated easy and difficult laryngoscopy. Twenty anaesthetists were allowed three attempts to intubate in each of four laryngoscopy scenarios in a high fidelity simulator. In the simulated easy laryngoscopy scenarios, the anaesthetists took longer to intubate using the GlideScope than the Macintosh laryngoscope (mean (SD) 19.0 (9.7) s vs. 12.7 (5.9) s, respectively; p = 0.006). There was no difference in the number of successful intubations, ease of intubation or choice of intubating device. In the simulated difficult laryngoscopy scenarios, the anaesthetists took less time to intubate using the GlideScope (23.5 (12.7) s vs. 70.5 (101.2) s, respectively; p = 0.001). The slightly higher success rate with the GlideScope was not statistically significant (20/20 vs. 18/20, respectively; p = 0.5). However, the anaesthetists found it easier to intubate using the GlideScope (median (interquartile range [range]) 1 (1-2 [1-2]) vs. 2 (2-3 [1-3]), respectively; p < 0.0001).

Effects of isoflurane and propofol on cortical somatosensory evoked potentials during comparable depth of anaesthesia as guided by bispectral index.

BACKGROUND: The aim of this study was to determine if propofol caused less suppression of cortical somatosensory evoked potentials (SSEPs) during spine surgery compared with isoflurane during comparable depth of anaesthesia as guided by bispectral index (BIS) measurements. METHODS: This was a randomized controlled trial of propofol and isoflurane involving 60 patients undergoing elective spine surgery. BIS monitoring was used to guide a consistent and comparable depth of anaesthesia, the index was maintained at between 40 and 50 during anaesthesia. The cortical SSEP P40-N50 peak-to-peak amplitude and latency time to the P40 peak were measured before induction of anaesthesia, after induction of anaesthesia, at the start of skin incision, at the start of pedicle screw insertion and at the start of rod insertion, by a neurophysiologist blinded to drug allocation. RESULTS: Both propofol and isoflurane decreased SSEP amplitude and increased latency during the course of anaesthesia. After achieving a comparable depth of anaesthesia, the SSEP amplitude was significantly lower with isoflurane, 1.5 (1.0) vs 2.4 (1.4) muV (P=0.005). Latency was significantly longer with isoflurane, 39.5 (3.9) vs 37.3 (3.1) ms (P=0.024). Isoflurane was associated with greater variability of SSEP amplitude during the course of anaesthesia and surgery, coefficient of variation 35.4 (18.0) vs 21.2 (10.2)% (P=0.008). CONCLUSIONS: Propofol anaesthesia caused less suppression of the cortical SSEP, with better preservation of SSEP amplitude, and less variability at an equivalent depth of anaesthesia.

Rates of caesarean section and instrumental vaginal delivery in nulliparous women after low concentration epidural infusions or opioid analgesia: systematic review.

OBJECTIVE: To compare the effects of low concentration epidural infusions of bupivacaine with parenteral opioid analgesia on rates of caesarean section and instrumental vaginal delivery in nulliparous women. DATA SOURCES: Medline, Embase, the Cochrane controlled trials register, and handsearching of the International Journal of Obstetric Anesthesia. STUDY SELECTION: Randomised controlled trials comparing low concentration epidural infusions with parenteral opioids. DATA SYNTHESIS: Seven trials fulfilled the inclusion criteria for meta-analysis. Epidural analgesia does not seem to be associated with an increased risk of caesarean section (odds ratio 1.03, 95% confidence interval 0.71 to 1.48) but may be associated with an increased risk of instrumental vaginal delivery (2.11, 0.95 to 4.65). Epidural analgesia was associated with a longer second stage of labour (weighted mean difference 15.2 minutes, 2.1 to 28.2 minutes). More women randomised to receive epidural analgesia had adequate pain relief, with fewer changing to parenteral opioids than vice versa (odds ratio 0.1, 0.05 to 0.22). CONCLUSIONS: Epidural analgesia using low concentration infusions of bupivacaine is unlikely to increase the risk of caesarean section but may increase the risk of instrumental vaginal delivery. Although women receiving epidural analgesia had a longer second stage of labour, they had better pain relief.

Monitored transtracheal jet ventilation using a triple lumen central venous catheter.

Two patients with nasopharyngeal carcinoma, radiotherapy treatment and 'difficult' airways were anaesthetised for oral surgery. A triple lumen central venous catheter was inserted through the cricoid membrane and transtracheal jet ventilation with an AMS 1000 jet ventilator was performed via the distal lumen. The middle and proximal lumens were connected to an airway pressure monitor and a capnograph, enabling breath-by-breath monitoring of ventilation.