Future directions for obstetric major haemorrhage

Summer has arrived and we are back from an excellent 2019 Trainee Conference in Telford. Highlights included: a keynote lecture from Professor Colin Melville on the General Medical Council and training; a talk on awake breast surgery from Amit Pawa; a debate on the role of social media in the medical profession; and a conference dinner and dance under the planes at RAF Cosford.

This month, Sullivan and Ralph present the results from a single centre retrospective cohort study evaluating the use of intra-operative cell salvage in 6352 obstetric patients. Between 2008 and 2017, cell salvage was used routinely for 98% of caesarean deliveries at the authors’ institution. They found a reduction in blood transfusion rates during the study period, whilst also demonstrating that routine cell salvage seems to be safe and economical. These results contrast with the SALVO randomised controlled trial which found no evidence of benefit with cell salvage. Wong and Toledo eloquently discuss the differences between observational studies and randomised controlled trials, which is always a hot topic on Twitter. They suggest further research is necessary before completely condemning the routine use of cell salvage, which is possibly at odds with the recent Association of Anaesthetists cell salvage guidelines

Point-of-care viscoelastic haemostatic assays are becoming increasingly popular. McNamara et al. present four years of prospective data following the introduction of a ROTEM algorithm for the treatment of coagulopathy in major obstetric haemorrhage (Fig. 1). They found a reduction in the use of blood products and the number of patients with transfusion associated circulatory overload. Most women experiencing haemorrhage did not have any evidence of coagulopathy, except in cases of placental abruption. Shah and Collis therefore ask, should we abandon the use of fixed ratio blood products in obstetrics, and should hypofibrinogenaemia be treated with cryoprecipitate or fibrinogen concentrate? These questions aside, knowledge of early haemostatic competence does have the potential to influence clinical management. If early results are normal, the focus can shift towards surgical causes of bleeding and allogeneic transfusions may be avoided. This is perhaps where the true benefit of using these new assays lies in the context of obstetric practice.

Figure 1 Number of units of blood and blood products per patient.

The use of dexamethasone as an adjunct to peripheral or central neuraxial blockade is controversial. Albrecht et al. report their randomised, triple-blind study to evaluate the effect of increasing doses of perineural dexamethasone on analgesia duration in patients requiring an interscalene brachial plexus block. They observed that perineural dexamethasone, with doses ranging between 1-4 mg, prolongs the duration of analgesia in a dose-dependent manner. Heeseen et al. undertook a meta-analysis to investigate the effect of intravenous dexamethasone on postoperative analgesia when given after spinal anaesthesia. They observed a significant reduction in 24-hour morphine consumption and significantly longer time to first analgesia request in the dexamethasone group as compared with the control group. Marhofer and Hopkins argue that, although there is no evidence that dexamethasone for regional anaesthesia causes harm, there are many good reasons why the evidential bar for a clinical benefit has not been met, yet.

Medication errors in peri-operative practice are commonSivia and Pandit have developed a new mathematical model to predict drug errors, which also incorporates the effect of operator fatigue. They observed that ~10% of operations lasting ~12 hours will result in a drug error, which is unacceptably high but consistent with other studies. Risks may be mitigated by anaesthetists recognising contributory factors such as illness, fatigue and working in unfamiliar environments. There have been many calls to move beyond labelling such problems as ‘human error’ and instead focus on continuously engineering human-centred safety systems. Carlisle and Merry discuss the science of reducing failure, and the possible applications and limitations of this new model. Time will tell us whether the safety of anaesthesia will improve as a result.

Figure 2 Modelling the probability of error over the course of an operation in which there are five drugs and tree possible routes for injection for three intrinsic error rates of 0.1% (green), 1% (blue) and 10% (red). The same result obtains for a scenario of three drugs and five possible routes for injection.

Excessive ambient noise in the critical care environment is a common patient compliant and can have negative sequalae. To address this problem, we must first isolate the source of the noise. Darbyshire et al. mapped the source of noise on a critical care unit and observed most loud sounds originated from very limited areas that were very close to patients’ ears. These noises may originate from bedside equipment and monitoring alarms, and simple redesign measures may be an effective way to reduce this environmental noise burden (Fig. 3).

Figure 3 Heat map which can be interpreted as average ‘noisiness’ map for the ICU bay. ‘Hotter’ colours (reds and yellows) indicate areas where loud noises are more frequent. The area of noise marked ‘1’ is outside the side room that was preferentially used, and shows where conversations between staff about the patient in the side room commonly took place. The areas of noise marked ‘2’ correspond to the positions of the telephones.

Bertaggia question the evidence we use to inform peri-operative practice through calculating the Fragility Index of all peri-operative randomised controlled trials reporting a significant effect of an intervention on mortality. They found that, for most trials, the significance of interventions was sensitive to only a few more deaths amongst participants. They suggest trialists should consider reporting the Fragility Index with studies, which is the number of participants without events who would have to experience events to increase p to ≥ 0.05. We look forward to inevitable debate over on Twitter! The first issue of Anaesthesia Reports has now been published! Recent reports include critical illness following topical application of a skin-lightening preparationmajor haemorrhage following vascular injury during exchange of cardiac pacemaker leadspre-operative ventricular bigeminy and cardiomyopathy; and critical illness in a patient with influenza A and sick cell trait.

Elsewhere, Weatherall compare portable blood warming devices under simulated pre-hospital conditions; Ki et al. find that a new EEG monitoring system (phase lag entropy) might be a useful hypnotic depth indicator in patients receiving propofol sedationKotoda et al. compare different methods of rigid stylet removal to minimise adverse force and tracheal tube movement; and Bojesen find that hypoxaemia after surgery for colorectal cancer is perhaps much more common than we might expect.

We recently issued two press releases for important articles with implications for anaesthetists, departments and hospitals. You can read all about peri-operative transoesophageal echocardiography-related complications and the Association of Anaesthetists survey on suicide amongst anaesthetists over on early view. Both articles are free forever. Finally, we are delighted to announce that our 2019 Impact Factor has increased by 8% to 5.9, according to the yearly Journal Citation Reports just published by Clarivate. Our journal is ranked 4th out of 31 in the category “Anesthesiology” and was the only journal in the top four to increase its Impact Factor in this year’s Report.

#onwardsandupwards

Professor Andrew Klein and Dr Akshay Shah

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