Difficult intubation and extubation in adult anaesthesia.

OBJECTIVE: To provide an update to French guidelines about "Difficult intubation and extubation in adult anaesthesia 2006". DESIGN: A consensus committee of 13 experts was convened. A formal conflict-of-interest (COI) policy was developed at the onset of the process and enforced throughout. The entire guidelines process was conducted independent of any industry funding. The authors were advised to follow the principles of the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system to guide assessment of quality of evidence. The potential drawbacks of making strong recommendations in the presence of low-quality evidence were emphasized. Few recommendations were ungraded. METHODS: The panel focused on 6 questions: 1) Why must oxygen desaturation be avoided during intubation and what preoxygenation and oxygenation techniques should be used to prevent it? 2) Should videolaryngoscopes be used instead of standard laryngoscopy with or without a long stylet to achieve a better success rate of intubation after the first attempt during anticipated difficult intubation off fiberoptic intubation? 3) Should TCI or target controlled inhalation anaesthesia (TCIA) be used instead of bolus sedation for airway control in the event of suspected or proven difficulty in a patient spontaneously breathing? 4) What mode of anaesthesia should be performed in patients with difficult intubation criteria and potentially difficult mask ventilation? 5) In surgical patients, what criteria predict difficulties encountered during postoperative tracheal extubation? 6) Should decision trees and algorithms be employed to direct decision-making for the management of difficult intubation, whether foreseen or not? (based on the information from the preceding five issues). Population, intervention, comparison, and outcomes (PICO) questions were reviewed and updated as needed, and evidence profiles were generated. The analysis of the literature and the recommendations were then conducted according to the GRADE® methodology. RESULTS: The SFAR Guideline panel provided 13 statements on difficult intubation and extubation in adult anaesthesia. After two rounds of discussion and various amendments, a strong agreement was reached for 99% of recommendations. Of these recommendations, five have a high level of evidence (Grade 1±), 8 have a low level of evidence (Grade 2±). No recommendation was provided for one question. CONCLUSIONS: Substantial agreement exists among experts regarding many strong recommendations for the best care of patients with difficult intubation and extubation in adult anaesthesia.

Estrogens are needed for the improvement in endothelium-mediated dilation induced by a chronic increase in blood flow in rat mesenteric arteries.

Resistance arteries play a key role in the control of local blood flow. They undergo outward remodeling in response to a chronic increase in blood flow as seen in collateral artery growth in ischemic disorders. We have previously shown that mesenteric artery outward remodeling depends on the endothelial estrogen receptor alpha. As outward arterial remodeling is associated with improved endothelium-dependent dilation, we hypothesized that estrogens might also play a role in flow-mediated improvement of endothelium-dependent dilation. Local increase in blood flow in first order mesenteric arteries was obtained after ligation of adjacent arteries in three-month old ovariectomized female rats treated with 17-beta-estradiol (OVX+E2) or vehicle (OVX). After 2 weeks, diameter was equivalent in high flow (HF) than in normal flow (NF) arteries with a greater wall to lumen ratio in HF vessels in OVX rats. Acetylcholine-mediated relaxation was lower in HF than in NF vessels. eNOS and caveolin-1 expression level was equivalent in HF and NF arteries. By contrast, arterial diameter was 30% greater in HF than in NF arteries and the wall to lumen ratio was not changed in OVX+E2 rats. Acetylcholine-mediated relaxation was higher in HF than in NF arteries. The expression level of eNOS was higher and that of caveolin-1 was lower in HF than in NF arteries. Acetylcholine (NO-dependent)-mediated relaxation was partly inhibited by the NO-synthesis blocker L-NAME in OVX rats whereas L-NAME blocked totally the relaxation in OVX+E2 rats. Endothelium-independent relaxation (sodium nitroprusside) was equivalent in OXV and OVX+E2 rats. Similarly, serotonin- and phenylephrine-mediated contractions were higher in HF than in NF arteries in both OVX and OVX+E2 rats in association with high ratio of phosphorylated ERK1/2 to ERK1/2. Thus, we demonstrated the essential role of endogenous E2 in flow-mediated improvement of endothelium (NO)-mediated dilatation in rat mesenteric arteries.

Role of estrogens and age in flow-mediated outward remodeling of rat mesenteric resistance arteries.

In resistance arteries, a chronic increase in blood flow induces hypertrophic outward remodeling. This flow-mediated remodeling (FMR) is absent in male rats aged 10 mo and more. As FMR depends on estrogens in 3-mo-old female rats, we hypothesized that it might be preserved in 12-mo-old female rats. Blood flow was increased in vivo in mesenteric resistance arteries after ligation of the side arteries in 3- and 12-mo-old male and female rats. After 2 wk, high-flow (HF) and normal-flow (NF) arteries were isolated for in vitro analysis. Arterial diameter and cross-sectional area increased in HF arteries compared with NF arteries in 3-mo-old male and female rats. In 12-mo-old rats, diameter increased only in female rats. Endothelial nitric oxide synthase expression and endothelium-mediated relaxation were higher in HF arteries than in NF arteries in all groups. ERK1/2 phosphorylation, NADPH oxidase subunit expression levels, and arterial contractility to KCl and to phenylephrine were greater in HF vessels than in NF vessels in 12-mo-old male rats only. Ovariectomy in 12-mo-old female rats induced a similar pattern with an increased contractility without diameter increase in HF arteries. Treatment of 12-mo-old male rats and ovariectomized female rats with hydralazine, the antioxidant tempol, or the angiotensin II type 1 receptor blocker candesartan restored HF remodeling and normalized arterial contractility in HF vessels. Thus, we found that FMR of resistance arteries remains efficient in 12-mo-old female rats compared with age-matched male rats. A balance between estrogens and vascular contractility might preserve FMR in mature female rats.

[Use of a single-use fiberscope for the training in tracheal intubation under fiberscopy on labyrinth]. / Utilisation d'un fibroscope à usage unique pour la formation sur labyrinthe à l'intubation sous fibroscope.

GOAL OF THE STUDY: To evaluate a single-use fiberscope, the Ascope-Trainer, for the training in the intubation under fiberscope. TYPE OF STUDY: Prospective randomized study approved by the local ethic committee. METHODOLOGY: After evaluation of their level of expertise, "experienced" or "novices" in intubation under fiberscope, the doctors attending the Training for Referents in Difficult Airway Management performed a test on labyrinth with a standard fiberscope (T1). After they were assigned to two groups, training with the Ascope-Trainer (group A, n=35) or with a classic fiberscope (group C, n=29), they trained during 15 minutes and performed a new test (T2). An analysis of variance was used to compare means. A goal for the training was determined according to the "experienced" doctors' mean T1. A test of Khi(2) was used for the comparison of the number of participants having reached this goal as well as the progress in both groups A and C. RESULTS: The T1 in the "experienced" group was 76 ± 31 s and the training improved significantly T2 (53 ± 17 s). Considering the novices, T2 was significantly lower than T1 in the group A (77 ± 38 s versus 135 ± 68 s) as well as in C (64 ± 28 s versus 122 ± 60 s), and the proportion of the novices having reached the goal of training was comparable in both groups. CONCLUSIONS: Because its use is similar to the standard fiberscope, the Ascope-Trainer may be interesting for this type of training.

Key role of estrogens and endothelial estrogen receptor α in blood flow-mediated remodeling of resistance arteries.

OBJECTIVE: Flow- (shear stress-)mediated outward remodeling of resistance arteries is involved in collateral growth during postischemic revascularization. As this remodeling is especially important during pregnancy, we hypothesized that estrogens may be involved. A surgical model eliciting a local increase in blood flow in 1 mesenteric resistance artery was used in 3-month-old ovariectomized female rats either treated with 17-ß-estradiol (E2) or left untreated. METHODS AND RESULTS: After 14 days, arterial diameter was greater in high-flow arteries than in normal-flow vessels. An ovariectomy suppressed high-flow remodeling, while E2 restored it. High-flow remodeling was absent in mice lacking the estrogen receptor α but not estrogen receptor ß. The kinetics of inflammatory marker expression, macrophage infiltration, oxidative stress, and metaloproteinases expression were not altered by the absence of E2 after 2 and 4 days, that is, during remodeling. Nevertheless, E2 was required for the increase in endothelial nitric oxide synthase expression and activation at day 4 when diameter expansion occurs. Finally, the impact of E2 on the endothelium appeared crucial for high-flow remodeling, as this E2 action was abrogated in mice lacking endothelial NOS, as well as in Tie2-Cre(+) ERα(f/f) mice. CONCLUSIONS: We demonstrate the essential role of E2 and endothelial estrogen receptor α in flow-mediated remodeling of resistance arteries in vivo.

[French clinical guidelines for prevention of perianaesthetic dental injuries: long text]. / Bris dentaires périanesthésiques: texte long.

INTRODUCTION: Dental injuries represent the most common claims against the anaesthesiologists. Dental lesions are frequent complications of orotracheal intubation and major causal factors are, firstly, preexisting poor dentition, and, secondly, difficult laryngoscopy and tracheal intubation. The aim of this work was to prioritize propositions for prevention in perianaesthetic dental injury and for care in case of dental trauma. METHOD: A GRADE consensus procedure consisting of three rounds was conducted. A purposively selected heterogeneous panel (n=15) of experts, comprising 10 practitioners in anesthesiology, one practitioner who is jurist and anaesthesiologist, two practitioners in maxillofacial surgery, and two practitioners in dentist surgery. In cases where the data did not appear conclusive, recommendations were based on the consensus opinion of the board members. The guidelines represent the best current evidence based on literature search and professional opinion. RESULTS: The entire panel completed all three rounds and 31 plus six propositions were written for adult and paediatric clinical practice in anaesthesiology, respectively. The experts highlight the interest of preoperative visit for minimizing dental injuries: the practitioner must identify risk factors for difficult intubation and ventilation, describe precisely patient's preoperative dental condition, including upper incisor most commonly involved teeth in dental trauma. Patients have to be informed by practitioner for risk dental injury and anaesthesiology staff must choose his anesthesia protocol before the induction of intubation narcosis, avoiding insufficient anaesthesia and lack of experience by the anaesthesiologist. The choice of accurate proceeding during laryngoscopy, tracheal intubation and extubation for example, can aid in the prevention of dental injury, reduce the number of claims and the cost of litigation process. DISCUSSION: These guidelines delineate an approach for the prevention of perianaesthetic dental trauma and for the immediate or urgent care in case of perianaesthetic dental injury.

Estrogen receptor actions on vascular biology and inflammation: implications in vascular pathophysiology.

Whereas hormonal therapy (HT) may increase the risk of coronary heart disease (CHD) and stroke in menopausal women, epidemiological studies (protection in premenopausal women) suggest and experimental studies (prevention of fatty streak development in animals) demonstrate a major atheroprotective action of estradiol (E2). The understanding of the deleterious and beneficial effects of estrogens is thus required at both a cellular and molecular level. Both the endothelium and the immuno-inflammatory system play a key role in the development of fatty streak deposit as well as in the rupture of the atherosclerotic plaque. Whereas E2 favors an anti-inflammatory effect in vitro (cultured cells), it rather elicits a pro-inflammatory response in vivo at the level of several subpopulations of the immuno-inflammatory system, which could contribute to plaque destabilization. E2 promotes beneficial actions on the endothelium such as nitric oxide and prostacyclin production. E2 actions are essentially mediated by two molecular targets: estrogen receptor alpha (ER-alpha) and beta (ER-beta), but the former appears to mediate most of the actions of E2 on the endothelium and on the immune system. ER-alpha modulates target gene transcription through two activation functions (AF), AF-1 and AF-2, even though signalling via ER-alpha located at the plasma membrane (responsible for membrane-initiated steroid signalling (MISS)/(extra-genomic)) can also lead to an indirect effect on gene transcription. Recently, we demonstrated that ER-alpha AF-1 is not required for the vasculoprotective actions of E2, whereas it is necessary for the effects of E2 on its reproductive targets. These results suggest that selective estrogen receptor modulators stimulating ER-alpha with minimal activation of ER-alpha AF-1 could retain beneficial vascular actions, while minimizing the sexual effects.

Cricoid cartilage and esophagus: CT scan study of the dynamic variability of their relative positions.

INTRODUCTION: Cricoid pressure occludes the esophagus (E) by compressing it between the cricoid cartilage (CC) and the body of the sixth cervical vertebra (C6). This technique is used to prevent passive regurgitation during the induction of anesthesia in patients at high risk for regurgitation. Failures of this technique had been described and a possible displacement of the E relative to the CC had been reported, but there is no study about displacement during antero-posterior movements of the head. AIM: The aim of our study was to evaluate the displacement of the CC relative to the cervical E, during flexion and extension movements of the head. MATERIALS AND METHODS: We retrospectively studied X-ray computed tomography (CT) images of 21 patients with suspected cervical trauma. Patients were in the supine position. In the first series of images, the head was positioned at maximal flexion by means of a support placed under the external occipital protuberance. In the second series of images, the head was maintained in extension by means of a support placed under the shoulders. Each position was obtained as far as possible within the limits of pain and restricted movement. In flexion and extension, we used the lowest slice from the cricoid cartilage. The variables measured were: diameters of CC (CD) and E (OD), left and right lateral displacements of E. RESULTS: A total of 13 CT were analyzed. CD and OD as well as OD/OC ratios did not vary significantly in flexion and extension. We noticed 61.5 and 92.3% (respectively in flexion and in extension) of left or right displacement: 23% of patients presented right displacement in both flexion and extension; 38.5% of patients did not present any right displacement in flexion or in extension; 61.5% of patients presented left displacement in both flexion and extension. More generally, almost 92% of patients presented displacement either in flexion or extension, or both. DISCUSSION: In our study, it can be seen that the E is clearly displaced with regard to the CC, that this displacement is favored by extension. Only 2/13 patients have an "over than 3 mm" displacement in extension whereas 5/13 in flexion. So, even if there are more displacements in extension, they are inferior to 3 mm and may not be considered as significant considering the occlusion of E. According to our results, the extension position of the head produces more displacement of the E but should preserve the containment of the cricoid pressure if we consider the thickness of the E wall.

[Open chest cardiopulmonary resuscitation: is there an interest in France?]. / Intérêts des manoeuvres de réanimation à thorax ouvert en France ?

OBJECTIVE: To expose and clarify indications, techniques, results, complications and cost for open chest cardiopulmonary resuscitation manoeuvres (OCCRM) in traumatic or nontraumatic cardiac arrest. DATA SOURCES: References were obtained from Pubmed data bank using the following keywords: "emergency thoracotomy", "resuscitative thoracotomy". STUDY SELECTION: We focused on publications in English language, from 2000 to 2007. DATA SYNTHESIS: OCCRM are useful especially in case of traumatic cardiac arrest, penetrating trauma, but also in blunt trauma. Time between cardiac arrest and realisation of the thoracotomy seems to be the most important factor for the prognosis. CONCLUSION: According to the French "physician in ambulance" prehospital system, OCCRM might be promising in France, because this system favours the fastness of care and therefore would minimize the time factor.

[Tracheal intubation through the intubating laryngeal mask airway training on manikin: comparison of single use and reusable devices from the same manufacturer]. / Apprentissage sur mannequin de l'intubation trachéale à l'aide d'un masque laryngé pour l'intubation : comparaison des dispositifs réutilisables et à usage unique d'un même fabricant.

INTRODUCTION: Recently, the French Society for Anaesthesia and Intensive Care (SFAR) has updated algorithms for difficult airway management, in which, the place of the intubating laryngeal mask (ILMA) is well defined. Moreover, in the guidelines, the SFAR recommended that the training for the different techniques for difficult intubation should initially be achieved on manikins. However, few data are available for disposable ILMA learning process on manikins. STUDY DESIGN: To compare, on manikin, the learning curves of the disposable and reusable ILMA. MATERIALS AND METHOD: Forty operators (anaesthesiologist, nurse, resident), experienced with conventional tracheal intubation but novice to commercially available ILMAs (Sebac, Pantin, France), underwent videotape learning and manikin training. After randomisation, each participant had to perform 10 timed consecutive tracheal intubations with either reusable or disposable ILMA. The learning curve was built according to the duration of successful procedure. Failure was considered if tracheal intubation could not be achieved or if the procedure lasted more than five minutes. RESULTS: No difference was noted between the two groups in terms of learning curves, number and repartition of the failed attempts during the learning process. CONCLUSION: This study shows that both disposable and reusable ILMA share similar learning process on manikins. Further studies are needed to evaluate the efficiency of the disposable ILMA in the clinical field of difficult intubation.

Role of inflammatory cytokines in the effect of estradiol on atheroma.

1. Although hormonal therapy (HT) may increase the risk of coronary heart disease (CHD) and stroke in postmenopausal women, epidemiological studies (protection in premenopausal women) suggest and experimental studies (prevention of fatty streak development in animals) demonstrate a major atheroprotective action of estradiol (E2). The understanding of the deleterious and beneficial effects of oestrogens is thus required. 2. The immuno-inflammatory system plays a key role in the development of fatty streak deposit as well as in the rupture of the atherosclerotic plaque. Although E2 favours an anti-inflammatory effect in vitro (cultured cells), it rather elicits a pro-inflammatory response in vivo involving several subpopulations of the immuno-inflammatory system, which could contribute to plaque destabilization. The functional role of several cytokines was explored in hypercholesterolemic mice. The atheroprotective effect of E2 was fully maintained in mice deficient in interferon-g or interleukin-12, as well as IL-10. In contrast, the protective effect of estradiol was abolished and even reversed in hypercholesterolemic mice given a neutralizing anti-transforming growth factor-b (TGF-b) antibody. Endothelium is another important target for E2, since it not only potentiates endothelial nitric oxide and prostacyclin production, but also controls trafficking of the populations of the immuno-inflammatory system. 3. To conclude, the respective actions of oestrogens on the cell populations involved in the pathophysiology of atherothrombosis may be influenced, among others, by the timing of HT initiation, the status of the vessel wall and, as recently demonstrated the status of the TGF-b pathway.

[Interest of entropy monitoring during low-grade cerebral aneurysm embolisation]. / Intérêt du monitorage de la profondeur d'anesthésie par entropie pour l'embolisation d'anévrismes intracrâniens de bas grade.

OBJECTIVE: Evaluate the use of entropy monitoring on anaesthetic drugs consumption, haemodynamic stability, and recovery time in patients undergoing embolisation of cerebral artery aneurysm (asymptomatic or low Hunt and Hess grades). METHODS: Two groups, G1 without entropy monitoring (Datex-Ohmeda S/5), G2 with entropy monitoring (16 patients in each group). Each group had similar anaesthetic protocol (propofol target control infusion and continuous intravenous infusion remifentanil). For G2, the state entropy (SE) values were kept between 35 and 45. We studied anaesthetic drug consumption, arterial pressure parameters, extubation delay and feasibility. Statistical analysis used Mann and Whitney test, Fisher test. Significativity was p<0.05. RESULTS: No intraoperative incident. Propofol consumption was lower in G2 (7.49+/-2.28 mg/kg per hour versus 9.46+/-2.50mg/kg per hour; p<0.05). A tendency to reduction was observed for remifentanil consumption (6.65+/-2.04 microg/kg per hour versus 7.94+/-2.92 microg/kg per hour; p=0.056), and extubation delay (14.1+/-8.6 min versus 26.5+/-22.0 min; p=0.056), in G2. The entropy monitoring had no repercussion on haemodynamic stability, but the arterial pressure values were significantly higher in G2 (73.60+/-8.49 mmHg versus 67.10+/-5.58 mmHg). Entropy captor does not disrupt embolisation procedure. Coils liberation alter temporarily RE and SE values.

[Anesthesia for video-assisted surgery of the thoracic and lumbar spine: a survey of 44 patients]. / Anesthésie pour chirurgie vidéoassistée du rachis thoracolombaire.

INTRODUCTION: The development of video-assisted surgery of the dorsolumbar spine has led to the need for adaptations for appropriate anesthetic management. Data concerning anesthesia for such surgery is very sparse in the literature. AIM OF THE STUDY: The aim of this retrospective study of 44 patients was to learn more about anesthesia practices used for patients undergoing this type of surgery. PATIENTS AND METHOD: The files of 44 patients were studied retrospectively. Epidemiologic data and the perioperative phase were analysed. RESULTS: The preoperative phase was not specific with preoperative assessment adapted to each patient. Similarly, monitoring practices during the surgical procedure were not specific. The choice of the anesthetic agents depended on the patient's clinical status. For tracheal intubation, care was taken to enable lung exclusion, even if not often used. Thoracic drainage at the end of the surgery was required in the event of imperfect hemostasis and in selected patients was replaced by pneumothorax exsufflation during closure. The postoperative period was uneventful and did not require admission to intensive care; non-specific analgesia was used. DISCUSSION: Adaptations of anesthetic practices are required each time a new surgical technique is developed. Excepting lung exclusion, anesthesia for video-assisted dorsolumbar spine surgery is not specific.

[Evaluation of a training method for transtracheal punction for emergency oxygenation]. / Ponction de la membrane intercricothyroïdienne pour l'oxygénation en urgence: évaluation d'une formation.

INTRODUCTION: Transtracheal oxygenation is a lifesaving technique in a cannot-ventilate, cannot-intubate situation, in setting percutaneous transtracheal catheter. OBJECTIVE: To assess training for cricoid membrane puncture performed with a Ravussin needle. METHOD: Ten residents in anaesthesiology nearing completion of their training participated in the study. Following a didactic session and a video demonstration, participants performed percutaneous transtracheal punctures on fresh cadavers. Success rate and time to perform the puncture were measured. Results are expressed as mean+/-SD. RESULTS: By the third attempt, all procedures were successful. Mean performance time at the first attempt was 31.2+/-21.8 s, progressively decreasing with the following attempts to reach a plateau by the third attempt (20.6+/-19.3s). Performance time varies with the cadaver's morphology and the ability to recognize anatomic landmarks. However, whatever the difficulty, performance time is 40 s or less by the third attempt. CONCLUSION: Percutaneous transtracheal catheter setting is a life saving technique with which every anaesthesiologist should be familiar. Viewing a pedagogic videotape and training on cadavers provides a rapid and effective training method for cricoid membrane puncture. Four attempts seem necessary to obtain an optimal success rate.