Innovation in anaesthesia

This month, we are delighted to publish papers on the design and evaluation of three novel devices aiming to address issues relevant to clinical practice. Firstly, Williams et al. have developed a syringe safety device to address the problem of syringe substitution errors. The device provides audio, visual and haptic feedback which supplements the visual cues provided by labelling, and can also help differentiate syringes containing vasoactive agents from other syringes. Darwood et al. have developed a simple, portable and potentially low-cost ventilator that uses a novel pressure-sensing approach and control algorithm (Fig 1). Both groups performed a series of successful benchtop experiments to test device performance, and studies evaluating clinical efficacy are now warranted. Batliner et al evaluated the performance of a novel flow-controlled syringe infusion pump at low flow rates against standard infusion syringe pumps in a laboratory study (Fig. 2). They found that the novel pump achieved a faster start-up to steady-state flow and more precise continuous drug delivery. The authors of all three studies should be commended on their efforts to develop solutions to important clinical problems. In the accompanying editorial, Peter Young discusses pathways to innovation and the issues that clinicians face when developing such devices, especially with regard to patents and intellectual property.

Figure 1 Unpacked test rig prototype: (a) motor and impeller; (b) pressure‐sensitive mechanical switch; (c) patient connection; (d) exhaust valve; (e) external pressure sensor (for experimental purposes); and (f) control board and microcontroller.

Figure 2 Functional principle of the flow‐controlled syringe infusion pump. Top: Picture of prototype flow‐controlled syringe pump. Bottom: Schematic principle of flow‐controlled syringe infusion pump. This system has a spring load mechanism (1) arranged to press against the plunger (2) of a disposable plastic syringe (3). The system is equipped with a real‐time flow rate sensor (4) and a pinch valve (5) to control the flow of the liquid by restricting the tube. The controller takes the flow rate as input to control the pinch valve.

We have recently published a series of articles related to fatigueburnout and wellbeing amongst anaesthetists. This month, Yentis et al. present the results of a survey investigating the experiences of anaesthetists related to the suicide of colleagues. The results are sobering. Of the 3638 responses received, nearly 40% had first-hand experience of a colleague’s suicide. Almost a third of respondents with experience of suicide reported more than one case. Most reported cases involved administration of commonly used anaesthetic drugs and occurred within the last 10 years. The vast majority of suicides occurred in doctors aged in their 30s and 40s. From an organisational perspective, nearly a quarter of suicide reports were deemed to be work-related. Many respondents were unaware of departmental or hospital policies on mental health, addiction or welfare. 

Potential solutions include: increasing awareness and support of mental health issues at work; developing local guidelines and pathways for managing work-related stress and substance abuse; and tighter control and accountability of access to anaesthetic drugs. In the accompanying editorial, David Scott discusses the impact of suicide on second victims. These are family members, friends and work colleagues of the victim, and there is often little or no support available to them. In addition to building supportive infrastructures, our focus should also be on the prevention of suicide. 

Aluminium release from fluid warming systems continues to generate interest. Taylor et al. found a significant uptake of aluminium into Plasma-Lyte 148 and compound sodium lactate fluids administered via an uncoated fluid warmer (Fig. 3).Lower levels were observed with blood product infusions but were still greater than the US Food and Drug Administration recommended levels. This study further validates the original findings by Perl et al. reported earlier this year. Using the example of excessive aluminium release being reported from uncoated fluid warming devices, McGuire et al. describe the processes by which the MHRA assessed the risk and implemented action to protect patients.

Figure 3 Mean aluminium concentration in three commonly used crystalloid solutions (● 0.9% saline; ♦compound sodium lactate ■Plasma‐Lyte 148) when run through an enFlow fluid warmer at 2 ml.min-1. Each datum point is the mean of two to five measurements (SD not displayed for clarity). “0 min” represents a room temperature baseline sample before attachment of the enFlow device. The US Food and Drug Administration maximal permitted aluminium level in i.v. nutrition is 25 μg.l-1 (0.9 μmol.l-1).

We have three articles in this month’s issue related to regional anaesthesia. Lyngeraa et al. investigated the analgesic effects of an adductor canal block using catheter-based boluses, either through a new suture-method catheter or a standard perineural catheter, compared with a single injection technique in patients undergoing total knee arthroplasty under spinal anaesthesia. They observed no difference in pain scores or opioid consumption between the study groups. However, muscle strength and ambulation on postoperative day 2 were better in the catheter-based bolus group irrespective of the type of catheter. Rao Kadam et al. demonstrated a marginal postoperative analgesic benefit of a transmuscular quadratus lumborum block compared with a surgical pre-peritoneal catheter in patients undergoing elective abdominal surgery. This marginal benefit should be balanced against the financial cost of a quadratus lumborum, which is $575 AUD more per patient. In a mechanistic study, Holmberg et al. used laser Doppler fluxmetry and capillary video microscopy to assess microcirculatory and nutritive blood flow following the addition of adrenaline to lidocaine in health volunteers undergoing infraclavicular brachial plexus blocks. The authors found that the addition of adrenaline reduces nutritive blood flow, but produces stronger and longer lasting blocks (Fig. 4).

Figure 4 Changes in nutritive blood flow: picture (a) shows functional capillary density between the first and second metacarpal on the dorsal side of the hand before infraclavicular block. Picture (b) shows functional capillary density in the same place in the same patient 30 min after infraclavicular block with adrenaline.

Gender imbalance is an important issue that requires addressing, particularly in academic medicine. Only 29% of UK professors in medicine are female, and anaesthesia has one of the lowest proportions of female professors (8%). In addition, only 25% of first authors in prominent science journals such as Nature and Science were female. A similar proportion has also been identified in anaesthetic journals (Fig. 5) .Laycock and Bailey investigated whether this also holds true for case reports submitted to Anaesthesia Cases. They hypothesised that such an imbalance may not present in more clinically-orientated publications, particularly as the proportion of female anaesthetic consultants and trainees is rising. Using an overall sample of 786 submissions over a 4.5-year period, they found that the proportion of female first authors of accepted case reports was 112/266 (42.1%). Importantly females were first authors in only 172/500 (34.4%) of rejected case reports. In view of these reassuring and positive findings, the authors make a strong call for tackling equity at all levels from medical school applications, through research funding, journals and editorial boards.

Figure 5 Proportion of female first authors in four anaesthesia journals. AC, Anaesthesia Cases; BJA, British Journal of Anaesthesia; Anesth, Anesthesiology; A&A, Anesthesia and Analgesia

Elsewhere, Charlesworth and van Zundert review the use of electronic health records and explore the possibility they may one day replace national anaesthesia databases. They highlight the ‘My Health Record’ initiative currently being implemented by the Australian government. There are clear advantages to such initiatives, such as easy access to high quality information, but this has to be balanced against concerns such as data privacy and the impact on current working practices. 

In our reviews section, Sharawi et al. conducted a systematic review to evaluate the quality of patient reported outcome measures (PROMs) to assess functional recovery following caesarean section. They used a COSMIN appraisal checklist to evaluate quality. They identified 13 PROMS but only one – the ‘Obstetric Quality of Recovery-11’, achieved the high COSMIN standards for any PROM. Kumar et al. provide insights into pharmacogenomics and ongoing pharmacogenetic research relevant to opioid drugs. They highlight the role single-nucleotide polymorphisms play in the variability we observe with the use of opioids in our daily clinical practice. Further research into such genetic factors will have an important role for personalised medicine in the future. This review is a must read. 

Over in Anaesthesia ReportsIreland et al report the use of a sacral plexus catheter for continuous local anaesthetic infiltration in a patient who sustained a unilateral sacral ala fracture following a fall from a horse. The catheter was successfully inserted under ultrasound guidance and resulted in satisfactory patient analgesia, mobilisation and chest physiotherapy. Finally, our next TweetChat will focus on a new paper from Marko Zdravković and colleagues, which is a large international survey on practices associated with rapid sequence intubation (#RapidSequence). This will take place at 1900 GMT on the 31stof October. You heard it here first!

Dr Akshay Shah and Professor Andrew Klein