Airway management research – what next?

This month, we are delighted to publish the first systematic bibliometric review of airway management research. This stemmed from a series of exchanges on the benefits, risks, and ethics of conducting airway research in manikins vs. patients. Ahmad et al. included 1505 studies published between 2006 and 2017, of which 1082 (71.9%) were patient studies and 322 (21.4%) were manikin studies (Figure 1). They observed an increase in the annual number of airway management studies over time. Patient studies mostly included elective ASA 1-2 patients and reported on tracheal intubation. A total of 77 primary outcomes were measured with success rate (27.4%) and procedure time (22.7%) the most common. Only seven trials used patient-centered primary outcomes and the authors highlight the need for a core outcome set. McGrenaghan and Smith agree with these sentiments and discuss how airway research may be conducted in the future.

Figure 1 Flow diagram demonstrating study subjects, study design and type of patient airway involved in experimental patient studies. Grey circles are for all studies, blue circles are for patient studies, green circles are for manikin studies and yellow circles are for all other subject types.

Supraglottic airway devices (SAD) play an important role in difficult airway management. In this retrospective registry study, Thomsen et al. describe the use of SADs in cases of difficult airway management. The Danish database is a unique repository and receives information from over 75% of Danish hospitals – their work is always of interest. From a cohort of 658,104 patients, difficult intubation occurred in 4898 (0.74%) cases. The most striking and perhaps worrying finding was that only 18.9% received a SAD in the course of their management. When SADs were used as rescue devices, they were successful two-thirds of the time. In their accompanying editorial, Ahmad and El-Boghdadly discuss possible reasons as to why SADs were so underutilised, and provide a framework for difficult airway management research (Figure 2). How does fibreoptic-guided tracheal intubation through a SAD compare between an I-gel® with the LMA® Protector™? Mendonca et al. observed no differences in mean intubation time, success rate, glottic view and ease of tracheal intubation.

Figure 2 Proposed framework for developing a difficult airway management research strategy.

The Global Capnography Project is arguably one of the most important projects in anaesthesia safety in the last decade. The results from their new study in Malawi support the development of an international project to help make global capnography provision a reality, so that like pulse oximetry, it can be included in the WHO surgical safety checklist and improve patient safety worldwide. In their accompanying editorial, Lipnick et al. call upon the global anaesthesia community (i.e. providers, researchers, national societies, manufacturers and donors) to accelerate research, education and development, manufacture, and distribution to make capnography accessible to anaesthesia providers in all practice settings.

Kwikiriza et al. report their RCT of intrathecal morphine versus ultra-sounded guided transverse abdominis plane block after caesarean section at a Ugandan regional referral hospital. Overall, the authors found both approaches were clinically effective in terms of providing adequate pain relief. The authors should be commended on this well-conducted study and for demonstrating the potential of using ultrasound in a low-resource setting. In the accompanying editorial, Bashford and Vercueil, provide suggestions on supporting and conducting such research and what role journals can play in developing and promoting authors from low‐ and middle‐income countries.

This case series on anaphylaxis to intravenous gelatin‐based solutions from Farooque et al. attracted plenty of attention during a TweetChat in December. Twelve patients were identified over a five-year period, 11 of which had severe or life-threatening reactions with three progressing to cardiac arrest. Unlike the classic presentation of anaphylaxis, which occurs within five minutes, the majority of patients developed signs/symptoms 10-70 minutes after administration. The commonest clinical features were cutaneous signs and hypotension. In view of the risk of severe allergy, along with the lack of any other clear benefits, is this the final nail in the coffin for the use of gelatins? Catch up with all the discussion on Twitter by searching for #Gelophylaxis.

The guidelines for the safe practice of total intravenous anaesthesia (TIVA) are a core document and essential reading for all anaesthetists (Figure 4). They have been extremely well received on social media with an Altmetric score of >300. Irwin and Wong argue that more work needs to be done on the practical education of TIVA and processed EEG monitoring so that more patients can benefit from this technique.

Figure 4 Key recommendations from the TIVA guidelines.

Elsewhere, Morrison et al. suggest that fibrinogen concentrate may be used as an alternative to fresh frozen plasma to treat hypofibrinogenemia and coagulopathy during thoraco-abdominal aortic aneurysm repair. Tabl et al. were unable to demonstrate non-inferiority in uterine tone induced at elective caesarean delivery by carbetocin 20 mg to that induced by carbetocin 100 mg. Wittenmeier et al. report that point of care and non-invasive haemoglobin measurement devices are still not reliable enough to replace the laboratory measurement in term and pre-term infants. Lastly, Ferguson & Dennis review the literature regarding various definitions of anaemia in pregnant women (Figure 5) and provide a framework for patient blood management in obstetrics.

Table 1 Definitions of anaemia in pregnancy in guidelines.

This blog follows an excellent Winter Scientific Meeting. Highlights from the journal session included Dr Kariem El-Boghdadly announcing the imminent arrival of Anaesthesia Reports (@Anaes_Reports), Professor Bruce Biccard’s talk on delivering pragmatic clinical trials in low resource settings, and Professor Peter Marfoher’s update in regional anaesthesia for shoulder surgery. Our journal workshop on ‘How to publish a paper’ also proved popular.