June 2018 – #TheAnaesthesiaBlog

Two years ago, joint guidelines from the AAGBI and British Hypertension Society were published. They were the first to advise on the measurement, diagnosis and management of raised blood pressure prior to planned surgery and were warmly welcomed by all stakeholders. Despite this clarity, peri-operative research on the consequences of pre-operative hypertension is lacking. This month, Crowther et al. report their study on the association between pre-operative hypertension and intra-operative haemodynamic instability. Though they conclude pre-operative hypertension may be more common than we think (48% vs. 30%), they were nonetheless unable to establish a link between pre-operative hypertension and the incidence of intraoperative haemodynamic instability. A key recommendation from the authors is these data support the current AAGBI hypertension guideline.

In this month’s statistically speaking, Choi and Wong explore the methods used and the conclusions deduced by Crowther et al. They discuss the difficulties of research on the consequences of pre-operative hypertension, the pitfalls of prospective observation and the clinical context of the study. They argue the study is inherently limited due to a low signal-to-noise ratio, and larger studies with more precise recruitment strategies will be required to better study the association between pre-operative hypertension and peri-operative morbidity.

Next, this retrospective observational study from Palmer et al. aims to elucidate the association between anaesthetic technique, operating room-to-incision interval and neonatal outcome in emergency caesarean section. Unsurprisingly, general anaesthesia was the quickest (6 minutes) followed by spinal anaesthesia (11 minutes), epidural top-up (13 minutes) and combined spinal-epidural (24 minutes). Alarmingly, general anaesthesia was associated with fewer 5-minute Apgar scores ≥ 7. Despite this finding, some have already highlighted several study limitations and engaged with the authors on Twitter. We look forward to seeing this discussion develop and we invite all interested parties to send us their letters.

In another observational study of 164 patients aged at least 65-years presenting for unscheduled surgery, McGuckin et al. evaluate the association between frailty and common postoperative surgical outcomes. Though the duration of hospital stay was independently associated with ASA physical status, surgical severity and two commonly used scoring systems (E-POSSUM and SORT), frailty, as measured by the Clinical Frailty Score, was not independently associated with hospital stay, morbidity, mortality or readmission.

The limitations of observational studies are well understood yet their conclusions may affect the way we care for patients. Though large pragmatic randomised controlled trials in peri-operative decision-making are seen by many as the gold standard, is this really the case? Joshi et al. set out the fundamental issues with such trials that may explain why negative results are commonand argue clinical practice may be falsely influenced through a failure to recognise these limitations. On the other hand, Yeung et al. set out the arguments for conducting large randomised trials and clarify when and how they should be performed. They argue the need for such studies has never been greater, and their limitations can be negated through more thoughtful trial design. When the results of large scale randomised trials are unwelcome or unexpected, do we simply dispute their findings due to our own biases? The debate will no-doubt continue.

There are three RCTs this month and all have important clinical consequences. The first is an investigation of the effect of spinal hyperbaric bupivacaine–fentanyl or hyperbaric bupivacaine on uterine tone and foetal heart rate (FHR) in labouring women.They find that spinal hyperbaric bupivacaine offers similar pain relief yet with a lower incidence of FHR abnormalities as compared with a hyperbaric bupivacaine-fentanyl combination. The second is a comparison of bolus phenylephrine or ephedrine for the treatment of hypotension in women with pre‐eclampsia undergoing caesarean section(you can read the recent associated consensus statement here!). They conclude 50 mcg phenylephrine and 4 mg ephedrine, administered as intravenous bolus doses, resulted in similar foetal acid‐base status and effectiveness in treating hypotension in pre‐eclamptic patients undergoing caesarean section. Finally, Mendonca et al. report their RCT comparing the ‘sniffing’ and neutral position using channelled (KingVision®) and non‐channelled (C‐MAC®) videolaryngoscopes(Figure 1). They failed to demonstrate any difference in ease of intubation between the positions for both types of videolaryngoscope and argue that videolaryngoscopy, like direct laryngoscopy, should be regarded as a dynamic process in which a change in position should be considered when difficulty is encountered.

Figure 1 Channelled, non‐channelled videolaryngoscopes and bougie used in the study. (a) KingVision with tracheal tube loaded in the channel. (b) C‐MAC with D‐Blade and (c) Frova intubating catheter (bougie).

The mode of anaesthesia for patients with hip fracture has been discussed at length for many years. In 2012, the AAGBI published their guideline for the management of proximal femoral fracturesand in 2016, following a secondary analysis of ASAP2 data, White, Moppett and Griffiths called for standardisation of anaesthetic practices. This month, we are delighted to publish this consensus statement on the principles of anaesthesia for patients with hip fracture. We encourage all who care for such patients to study these principles and for hospitals to incorporate each into local protocols. The core principle is simply to do your best for every patient. Refreshingly, particular techniques, drugs or modes of anaesthesia are not definitively prescribed.

Elsewhere this month, there is a benchtop study of changes in hardness and resilience of i‐gel^TMcuffs with temperature, a systematic review of topical benzydamine for prevention of postoperative sore throat in adults undergoing tracheal intubation, a meta-analysis of combined spinal‐epidural vs. spinal anaesthesia for caesarean sectionand an excellent discussion of the law around caring for obstetric patients with mental illness. Have you been involved with the management of an interesting case recently? Please consider writing it up for our sister journal, Anaesthesia Cases. Recent cases include acute postoperative compartment syndrome in a child receiving patient-controlled analgesia and peripheral nerve blockand Takotsubo cardiomyopathy secondary to needle phobia (this one received a lot of interest on social media!).

Finally, congratulations to our new fellow, Dr Akshay Shah, a talented NIHR Doctoral Research Fellow from Oxford. We look forward to Akshay joining the editorial team at the AAGBI Annual Congress in Dublin. The standard of applicants this year was exceptionally high, and our commiserations go to those who were unsuccessful. We have recently taken the decision to concentrate efforts on our Twitter accountinstead of our Facebook page. We do, however, have an Instagram accountwhere you can find out which paper is freely available each day and gain an insight into the day to day business of the journal. Finally, we will have a fresh new journal design from September onwards and we look forward to hearing what you think. Several articles in the new design are available now over on early view.

That’s all for now, but we hope to see you in a couple of weeks for the GAT annual scientific meeting in Glasgow!