Preoperative fasting and the risk of pulmonary aspiration-a narrative review of historical concepts, physiological effects, and new perspectives.

In the early days of anaesthesia, the fasting period for liquids was kept short. By the mid-20th century 'nil by mouth after midnight' had become routine as the principles of the management of 'full stomach' emergencies were extended to include elective healthy patients. Back then, no distinction was made between the withholding of liquids and solids. Towards the end of the last century, recommendations of professional anaesthesiology bodies began to reduce the fasting time of clear liquids to 2 h. This reduction in fasting time was based on the understanding that gastric emptying of clear liquids is rapid, exponential, and proportional to the current filling state of the stomach. Furthermore, there was no evidence of a link between drinking clear liquids and the risk of aspiration. Indeed, most instances of aspiration are caused by failure to identify aspiration risk factors and adjust the anaesthetic technique accordingly. In contrast, long periods of liquid withdrawal cause discomfort and may also lead to serious postoperative complications. Despite this, more than two decades after the introduction of the 2 h limit, patients still fast for a median of up to 12 h before anaesthesia, mainly because of organisational issues. Therefore, some hospitals have decided to allow patients to drink clear liquids within 2 h of induction of anaesthesia. Well-designed clinical trials should investigate whether these concepts are safe in patients scheduled for anaesthesia or procedural sedation, focusing on both aspiration risk and complications of prolonged fasting.

Use of the GlideScope®-Ranger for pre-hospital intubations by anaesthesia trained emergency physicians - an observational study.

BACKGROUND: Pre-hospital endotracheal intubation is more difficult than in the operating room (OR). Therefore, enhanced airway management devices such as video laryngoscopes may be helpful to improve the success rate of pre-hospital intubation. We describe the use of the Glidescope®-Ranger (GS-R) as an alternative airway tool used at the discretion of the emergency physician (EP) in charge. METHODS: During a 3.5 year period, the GS-R was available to be used either as the primary or backup tool for pre-hospital intubation by anaesthesia trained EP with limited expertise using angulated videolaryngoscopes. RESULTS: During this period 672 patients needed pre-hospital intubation of which the GS-R was used in 56 cases. The overall GS-R success rate was 66 % (range of 34-100 % among EP). The reasons for difficulties or failure included inexperience of the EP with the GS-R, impaired view due to secretion, vomitus, blood or the inability to see the screen in very bright environment due to sunlight. CONCLUSION: Special expertise and substantial training is needed to successfully accomplish tracheal intubation with the GS-R in the pre-hospital setting. Providers inexperienced with DL as well as video-assisted intubation should not expect to be able to perform tracheal intubation easily just because a videolaryngoscope is available. Additionally, indirect laryngoscopy might be difficult or even impossible to achieve in the pre-hospital setting due to impeding circumstances such as blood, secretions or bright sun-light. Therefore, videolaryngoscopes, here the GS-R, should not be considered as the "Holy Grail" of endotracheal intubation, neither for the experts nor for inexperienced providers.

Trauma-hemorrhage and hypoxia differentially influence kupffer cell phagocytic capacity: role of hypoxia-inducible-factor-1alpha and phosphoinositide 3-kinase/Akt activation.

OBJECTIVE: We investigated whether Kupffer cell phagocytosis is differentially regulated following hypoxia (by breathing hypoxic gas) and trauma-hemorrhage. We hypothesized that the differences might result from a differential activation of hypoxia-inducible factor (HIF)-1alpha and phosphoinositide 3-kinase (PI3K)/Akt pathway under those conditions. BACKGROUND: HIF-1alpha is a biologic O2 sensor enabling adaptation to hypoxia. Studies have shown that under hypoxic conditions, HIF-1alpha enhances macrophage phagocytosis. Trauma-hemorrhage also produces a hypoxic insult with HIF-1alpha activation; however, macrophage phagocytosis is suppressed under those conditions. Thus, signaling molecules other than HIF-1alpha should be taken into consideration in the regulation of macrophage phagocytosis following cellular hypoxia or trauma-hemorrhage. METHODS: Male C3H/HeN mice were subjected to sham operation, trauma-hemorrhage (laparotomy, 90 minutes hemorrhagic shock, MAP 35 +/- 5 mm Hg followed by resuscitation) or hypoxia (5% O2 for 120 minutes). The trauma-hemorrhage and hypoxia groups received Wortmannin (PI3K inhibitor), YC-1 (HIF-1alpha inhibitor) or vehicle at the time of maximum bleedout in the trauma-hemorrhage group or at a PaO2 of 30 mm Hg during hypoxic air inhalation. Mice were killed 2 hours later and samples/cells collected. RESULTS: While the systemic and Kupffer cell hypoxic states were similar in the trauma-hemorrhage and hypoxia groups, phagocytic capacity was suppressed following trauma-hemorrhage but enhanced in the hypoxia group. Kupffer cells from both groups showed increased HIF-1alpha activation, which was prevented by Wortmannin or YC-1 treatment. The increase in Kupffer cell phagocytosis following hypoxemia was also prevented by Wortmannin or YC-1 treatment. Akt activation was suppressed in the trauma-hemorrhage group, but enhanced in the hypoxia group. Wortmannin and YC-1 treatment prevented the increase in Akt activation. CONCLUSIONS: These findings indicate that the suppression of Kupffer cell phagocytosis following trauma-hemorrhage is independent of cellular hypoxia and activation of HIF-1alpha, but it is possibly related to suppression of the Akt activation.

Mechanism of the salutary effects of estrogen on kupffer cell phagocytic capacity following trauma-hemorrhage: pivotal role of Akt activation.

Kupffer cells are macrophages in the liver whose major role is to clear circulating pathogens. Decreased phagocytic capacity of Kupffer cells may result in severe systemic infection. We tested the hypothesis that the depressed Kupffer cell phagocytic capacity following trauma-hemorrhage is enhanced by estrogen administration and this occurs due to maintenance of Fc receptor expression and cellular ATP content via the activation of Akt. Male C3H/HeN mice were subjected to sham operation or trauma-hemorrhage and sacrificed 2 h thereafter. Estrogen, with or without an estrogen receptor antagonist (ICI 182,780), a PI3K inhibitor (Wortmannin), or vehicle, was injected during resuscitation. Kupffer cell phagocytic capacity was tested in vivo. The expression of Fc receptors, of Akt phosphorylation, of p38 MAPK phosphorylation, of DNA binding activity of NF-kappaB and ATP content of Kupffer cells were also determined. Trauma-hemorrhage suppressed Kupffer cell phagocytosis by decreasing Fc receptor expression and Akt activation; however, it induced p38 MAPK activation and increased NF-kappaB activity. Cellular ATP levels were also decreased following trauma-hemorrhage. Administration of estrogen following trauma-hemorrhage increased phospho-Akt levels and normalized all the parameters described as well as plasma levels of TNF-alpha, IL-6, and IL-10. Coadministration of ICI 182,780 or Wortmannin abolished the beneficial effects of estrogen in improving the phagocytic capacity of Kupffer cells following trauma-hemorrhage. Thus, activation of Akt plays a crucial role in mediating the salutary effect of estrogen in restoring trauma-hemorrhage-induced suppression of Kupffer cell phagocytosis.

Estrogen suppresses cardiac IL-6 after trauma-hemorrhage via a hypoxia-inducible factor 1 alpha-mediated pathway.

Cardiac dysfunction is a major concern after trauma-hemorrhage, and increased IL-6 is one of the underlying causes for producing the dysfunction. Studies have shown that administration of 17beta-estradiol (estrogen) after trauma-hemorrhage normalized cardiac IL-6 levels and restored cardiac functions under those conditions. Because hypoxia-inducible factor (HIF) 1 alpha is expressed during hypoxia and cellular stress and up-regulates the expression of IL-6, we hypothesized that HIF-1 alpha induces the increased cardiac IL-6 after trauma-hemorrhage and that estrogen suppresses this induction. To examine this, C3H/HeN mice were subjected to trauma-hemorrhage or sham operation. Vehicle, the HIF-alpha inhibitor YC-1 [3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole, a novel activator of platelet guanylate cyclase], or estrogen was administered to trauma-hemorrhage and sham groups during resuscitation. Mice were killed at 2 h after resuscitation, and cardiac IL-6, HIF-1 alpha, and nuclear factor (NF) kappaB activities were measured. IL-6, NF-kappaB, and HIF-1 alpha levels were markedly elevated after trauma-hemorrhage; all of these parameters were normalized by estrogen as well as YC-1 administration after trauma-hemorrhage. Because elevated IL-6 levels after trauma-hemorrhage were decreased with YC-1 treatment, it indicates that IL-6 expression in cardiomyocytes is induced via HIF-1 alpha. In addition, estrogen decreased the elevated HIF-1 alpha, NF-kappaB, and IL-6 levels after trauma-hemorrhage. These results indicate that the beneficial effects of estrogen on cardiac function after trauma-hemorrhage seem to be mediated by the inhibition of HIF-1 alpha expression and activity.

Out-of-hospital airway management with the LMA CTrach--a prospective evaluation.

AIM OF THE STUDY: Airway management in an out-of-hospital setting is a critical and demanding skill. Previous studies evaluated the intubating laryngeal mask airway (ILMA) as a valuable tool in this area. The LMA CTrach Laryngeal Mask Airway (CTrach) may increase intubation success. Therefore, we evaluated the CTrach as the primary tool for airway management in the out-of-hospital setting in adult patients. METHODS: From October 2006 until September 2007 EAN and SGR included all patients who needed advanced airway management during out-of-hospital emergency medicine service. Ventilation and intubation has been performed via the CTrach as the primary choice. Before intubation, visualization of the vocal cords was optimized under continuous ventilation via the CTrach. The time needed, manoeuvres to optimize vision, grades of vision and success rates have been documented. RESULTS: 16 patients have been included. Ventilation and intubation via the CTrach was possible in all patients. Ventilation was mostly established in less than 15s and was established in 15 of 16 (94%) patients at the first attempt. Intubation was successful in 15 of 16 (94%) patients on the first attempt. Visualization of the laryngeal structures was achieved in 69% of patients, while intubation without sight was performed in 31%, respectively. CONCLUSION: In this study, ventilation and intubation via the CTrach was successful and could be rapidly established in all patients. Our data suggest that the use of the CTrach may be suitable for the out-of-hospital setting as it provides ventilation and facilitates intubation with a very high success rate.

The role of oxygen termination of nanocrystalline diamond on immobilisation of BMP-2 and subsequent bone formation.

Medical implants are increasingly often inserted into bone of frail patients, who are advanced in years. Due to age, severe trauma or pathology-related bone changes, osseous healing at the implant site is frequently limited. We were able to demonstrate that coating of endosseous implants with nanocrystalline diamond (NCD) allows stable functionalization by means of physisorption with BMP-2. Strong physisorption was shown to be directly related to the unique properties of NCD, and BMP-2 in its active form interacted strongly when NCD was oxygen-terminated. The binding of the protein was monitored under physiological conditions by single molecule force spectroscopy, and the respective adsorption energies were further substantiated by force-field-calculations. Implant surfaces refined in such a manner yielded enhanced osseointegration in vivo, when inserted into sheep calvaria. Our results further suggest that this technical advancement can be readily applied in clinical therapies with regard to bone healing, since primary human mesenchymal stromal cells strongly activated the expression of osteogenic markers when being cultivated on NCD physisorbed with physiological amounts of BMP-2.

Self-reported changes in attitude and behavior after attending a simulation-aided airway management course.

STUDY OBJECTIVE: To evaluate the influence of a simulator-aided course for airway management on participants' daily clinical airway management practice. DESIGN: Survey instrument. SETTING: University hospital. PARTICIPANTS: 88 participants who attended a simulator-aided course for airway management. INTERVENTION: Six mo after 4 consecutive courses with identical structure and content, participants were mailed a standardized questionnaire to answer. MEASUREMENTS AND MAIN RESULTS: Of 88 participants queried, 48 completed the questionnaire. Ninety-two percent had experienced a difficult airway situation in the 6 mo after the course. Fourteen (29%) evaluated predictors for a difficult airway more carefully. Fourteen (29%) established structural changes within their departments. Ten (21%) participants acquired new technical airway devices. The mean estimated impact on the participants' rating for lectures, skill stations, and scenarios on a scale from 1 (very helpful) to 6 (not at all helpful) was 2.8 for lectures, 1.6 for skill stations, and 1.4 for scenarios. CONCLUSIONS: Attendance at a simulator-aided airway management course has a significant impact on self-reported accuracy and confidence in evaluation of airways, use of alternative airway devices, and changes in the practitioner's clinical practice toward difficult airway situations.

Trauma-haemorrhage-induced alterations in thymic prolactin receptor expression: implications in immune dysfunction.

Male gender and age appear to be causative factors in development of immunodepression and septic complications following trauma-haemorrhage. Studies have demonstrated that administration of the sex hormone prolactin following trauma-haemorrhage in male mice prevents immunodepression. Since the thymus is the primary location of the T-cell-lymphopoiesis, we investigated the effect of trauma-haemorrhage to thymic prolactin-receptor (PRLr)-expression in male and proestrus female mice in three different age groups (young, adult, aged) by flow cytometry and PCR. C3H/HeN mice were subjected to laparotomy (i.e., soft-tissue trauma) and hemorrhagic shock (35+/-5mmHg for 90min, then resuscitated) or sham operation. Twenty-four hours later thymocytes were isolated. Trauma-haemorrhage upregulated PRLr expression in young and mature mice of both genders, however, the increase was attenuated in females. In contrast, in aged mice PRLr expression was elevated in both genders, independent of trauma-haemorrhage and was not further increased under such conditions. These findings suggest that the gender dimorphism in the immune response to trauma-haemorrhage may in part be related to differences in thymic PRLr expression under such conditions.