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To evaluate the role of the phosphatidylinositol 3 kinase (PI3K)/protein kinase B (Akt)/hypoxia-inducible factor 1α (HIF-1α) signaling pathway in the protection by dexmedetomidine against lung ischemia–reperfusion injury (IRI) in rats. Forty-eight male Sprague–Dawley rats weighing 250–350 g were randomly divided into six groups (n = 8 each group): sham group, IRI group, low-dose dexmedetomidine group (LD group), high-dose dexmedetomidine group (HD group), combined low-dose dexmedetomidine and LY294002 group (LDL group), and combined high-dose dexmedetomidine and LY294002 group (HDL group). A 30-min ischemia was induced by occluding the hilum of the left lung, followed by a 120-min reperfusion by removing occlusion of the hilum. After the left lung was removed, the wet/dry weight ratio (W/D) of the lung tissues was determined. Pathological changes of lung tissues were evaluated by light and electron microscopes and the expression of p-Akt and HIF-1α in the lung tissues was determined by western blotting. Compared with the sham group, both the W/D ratio and lung injury were significantly increased, the p-Akt expression was down-regulated and HIF-1α expression was up-regulated in the five experimental groups. Compared with the LD and LDL groups, both the W/D ratio and lung injury were decreased, but the expression of p-Akt and HIF-1α was increased in the HD and HDL groups. Administration of dexmedetomidine before ischemia can provide a protection against lung IRI by re-installing the PI3K/Akt/HIF-1α signaling pathway.

1. Arslan ZI, Alparslan V, Ozdal P, Toker K, Solak M. Face-toface tracheal intubation in adult patients: a comparison of the AirtraqTM, GlidescopeTM and FastrachTM devices. J Anesth. 2015;29:893–8. 2. Ueshima H, Asai T. Tracheal intubation in daylight and in the dark: a randomised comparison of the Airway Scope, Airtraq, and Macintosh laryngoscope in a manikin. Anaesthesia. 2010;65:684–7. To the Editor

To the Editor: In a double-blind randomized controlled clinical trial comparing dexmedetomidine and remifentanil sedation for awake fiberoptic nasotracheal intubation, Hu et al. [1] showed that both drugs were effective. Moreover, compared with remifentanil, dexmedetomidine produced better endoscopy scores, lower incidence of recall, greater patient satisfaction, and fewer hemodynamic effects. They should be applauded for their efforts to provide useful evidence regarding dexmedetomidine and remifentanil sedation for awake airway management. However, in preparing the patient for awake intubation, the optimal sedation regimen would provide comfort and sedation as well as prevention from negative recall of the procedure. Furthermore, it should ensure good airway reflex suppression under sufficient spontaneous ventilation, hemodynamic stability, and adequate intubating conditions [2]. Based on the findings of this study, we are not sure that some of above targets have been well achieved. First, coughing during awake intubation occurred in 50 % of patients in the dexmedetomidine group and 15 % of patients in the remifentanil group, respectively. It is generally believed that during awake intubation, coughing is frequently reported as one of the most distressing symptoms and described as an undesirable feature [3]. Second, 30–40 % of patients in the dexmedetomidine group and 65–70 % of patients in the remifentanil group had recall for airway procedure events. Such high incidences of recall would put patients at a risk of postoperative psychological morbidity, such as anxiety, depression, posttraumatic stress disorder, cognitive impairment, etc. A main limitation of this study design is the use of a single agent to provide sedation. Actually, none of the drugs currently in use can meet all criteria of the optimal sedation regimen for awake intubation, although many of them have some of the desirable characteristics. For example, opioids can provide analgesia and help blunt airway reflexes, but use of opioids alone fails to provide amnesia [4]. Benzodiazepines have no analgesic effect, but are useful for providing good amnesia, even if the procedure itself appears to be painful. Thus, it is generally recommended that an optimal sedation regimen for awake intubation requires the use of a combination of sedatives, analgesics, and antipsychotic agents [4]. For example, midazolam and propofol, are common agents used for sedation, often with an opioid drug such as fentanyl or remifentanil. It must be pointed out that in a review of four studies, including 443 cases of awake intubation, even if various combinations of sedatives and analgesics are utilized, 17 % of patients still have partial recall and 6 % have recall with unpleasant memories [4]. Dexmedetomidine is a highly selective a2-agonist with anxiolysis and some analgesia without respiratory depression. An answer to this letter to the editor is available at doi:10.1007/s00540-013-1561-4.

To the Editor: In a randomized crossover manikin study by Saito and colleague [1] comparing intubation performance of the Coopdech videolaryngoscope Portable VLP-100 (VLP100), AirwayScope (AWS), and Macintosh laryngoscope, all study participants were residents trained in the anesthesia department for more than 1 month, and prestudy training comprised only a demonstration of the intubation technique and verbal instructions regarding the correct use of the studied devices. An important issue ignored by the authors is that a different learning curve is required for each of the three devices. Hirabayashi [2] showed that a short demonstration of the AWS and brief practice with a manikin were the only requirements needed to perfect a tracheal intubation with this device. No study has evaluated the learning curve of the VLP-100, but videolaryngoscopes similar to the Macintosh laryngoscope, such as the V-MAC videolaryngoscope, have shown a rapid learning curve [3]. In contrast, direct laryngoscopic intubation is a complex skill that is difficult to acquire: its success rate is only 50 % in novices and a success rate of 90 % cannot be expected until 50 attempts have been made [4]. These findings suggest that less training is required to achieve proficiency with the AWS and VLP-100 than with the Macintosh laryngoscope. Thus, in the authors’ study, identical prestudy training for the three devices may have biased both intubation time and success rate into the two videolaryngoscopes, especially for difficult airway scenarios. We emphasize that for results of a comparative study to be valid, participants must be equally proficient with each studied device in order to avoid bias. The difference in laryngoscopic views among the three laryngoscopes was stated as a final end-point of performance comparison. We argue that comparing the views obtained with direct and video laryngoscopes is not an entirely appropriate comparison. The Cormack–Lehane classification was originally designed to estimate the glottic views obtained by the Macintosh laryngoscope in which obtaining a full glottic view requires aligning the oral, pharyngeal, and laryngeal axes [5]. However, videolaryngoscopes can provide a full glottic view without the need for such alignment [3]. Moreover, Saito et al.’s study did not allow the use of measures to improve the laryngoscopic view. Although such manipulations are rarely needed for videolaryngoscopy, it can frequently improve direct laryngoscopic view and should be an inherent part of direct laryngoscopy in case of a poor glottic view [5]. Neglecting this factor would surely underestimate performance of the Macintosh laryngoscope. Because the AWS incorporates a tube channel, successful intubation does not require a stylet. It would be interesting to know whether the tracheal tube with a stylet was used for intubation with the VLP-100 or Macintosh laryngoscope. Because the VLP-100 does not create a direct channel for tube passage, the tube must be maneuvered around the device and the tongue to the glottis. In this case, use of a stylet to preform a tube is very helpful for bringing An answer to this letter to the editor is available at doi:10.1007/s00540-012-1535-y.