Selection of baseline blood pressure to guide management of hypotension during spinal anaesthesia for caesarean section

IntroductionRecommendations on vasopressor management during caesarean section under spinal anaesthesia suggest maintaining systolic arterial pressure ≥90% of an accurately measured baseline value. The baseline is often taken as the first reading in the operating room. We hypothesise that this reading may not reflect an accurate baseline value.MethodsA retrospective case note review of 300 non-hypertensive women undergoing caesarean section with neuraxial anaesthesia, including spinal anaesthesia for elective delivery (n=100), and spinal (n=100) and epidural top-up anaesthesia (n=100) for emergency delivery. Systolic arterial pressure values recorded at various time points between the last antenatal visit and the first blood pressure value recorded in the operating room were compared.ResultsThere was a stepwise and significant increase in systolic arterial pressure over three time points (last antenatal clinic, morning of surgery, operating room) before elective caesarean section (all P <0.001). In women having emergency caesarean under spinal anaesthesia, a stepwise increase over four time points (last antenatal clinic, first reading in labour, final reading in labour, operating room) was observed. A similar trend was seen over these time points for women having emergency caesarean under epidural top-up, although the systolic blood pressure did not rise during labour.ConclusionsUsing the initial blood pressure reading in the operating room as the baseline value may lead to unnecessary vasopressor use and hypertension. Prospective research is required to clarify which reading represents the most accurate baseline to maintain homeostasis and reduce the hypotensive sequelae of neuraxial anaesthesia for both the mother and fetus.     

The use of artificial intelligence and robotics in regional anaesthesia

The current fourth industrial revolution is a distinct technological era characterised by the blurring of physics, computing and biology. The driver of change is data, powered by artificial intelligence. The UK National Health Service Topol Report embraced this digital revolution and emphasised the importance of artificial intelligence to the health service. Application of artificial intelligence within regional anaesthesia, however, remains limited. An example of the use of a convoluted neural network applied to visual detection of nerves on ultrasound images is described. New technologies that may impact on regional anaesthesia include robotics and artificial sensing. Robotics in anaesthesia falls into three categories. The first, used commonly, is pharmaceutical, typified by target-controlled anaesthesia using electroencephalography within a feedback loop. Other types include mechanical robots that provide precision and dexterity better than humans, and cognitive robots that act as decision support systems. It is likely that the latter technology will expand considerably over the next decades and provide an autopilot for anaesthesia. Technical robotics will focus on the development of accurate sensors for training that incorporate visual and motion metrics. These will be incorporated into augmented reality and visual reality environments that will provide training at home or the office on life-like simulators. Real-time feedback will be offered that stimulates and rewards performance. In discussing the scope, applications, limitations and barriers to adoption of these technologies, we aimed to stimulate discussion towards a framework for the optimal application of current and emerging technologies in regional anaesthesia.     

Updates in our understanding of local anaesthetic systemic toxicity: a narrative review

Despite advances in clinical practice, local anaesthetic systemic toxicity continues to occur with the therapeutic use of local anaesthesia. Patterns of presentation have evolved over recent years due in part to the increasing use of ultrasound which has been demonstrated to reduce risk. Onset of toxicity is increasingly delayed, a greater proportion of clinical reports are secondary to fascial plane blocks, and cases are increasing where non-anaesthetist providers are involved. The evolving clinical context presents a challenge for diagnosis and requires education of all physicians, nurses and allied health professionals about these changing patterns and risks. This review discusses: mechanisms; prevention; diagnosis; and treatment of local anaesthetic systemic toxicity. The local anaesthetic and dose used, site of injection and block conduct and technique are all important determinants of local anaesthetic systemic toxicity, as are various patient factors. Risk mitigation is discussed including the care of at-risk groups, such as: those at the extremes of age; patients with cardiac, hepatic and specific metabolic diseases; and those who are pregnant. Advances in the changing clinical landscape with novel applications and settings for the use of local anaesthesia are also described. Finally, we signpost future directions to potentially improve the management of local anaesthetic systemic toxicity. The utility of local anaesthetics remains unquestionable in clinical practice, and thus maximising the safe and appropriate use of these drugs should translate to improvements in patient care.     

Incidence of accidental awareness during general anaesthesia in obstetrics: a multicentre,prospective cohort study

General anaesthesia for obstetric surgery has distinct characteristics that may contribute towards a higher risk of accidental awareness during general anaesthesia. The primary aim of this study was to investigate the incidence, experience and psychological implications of unintended conscious awareness during general anaesthesia in obstetric patients. From May 2017 to August 2018, 3115 consenting patients receiving general anaesthesia for obstetric surgery in 72 hospitals in England were recruited to the study. Patients received three repetitions of standardised questioning over 30 days, with responses indicating memories during general anaesthesia that were verified using interviews and record interrogation. A total of 12 patients had certain/probable or possible awareness, an incidence of 1 in 256 (95%CI 149–500) for all obstetric surgery. The incidence was 1 in 212 (95%CI 122–417) for caesarean section surgery. Distressing experiences were reported by seven (58.3%) patients, paralysis by five (41.7%) and paralysis with pain by two (16.7%). Accidental awareness occurred during induction and emergence in nine (75%) of the patients who reported awareness. Factors associated with accidental awareness during general anaesthesia were: high BMI (25–30 kg.m^-2); low BMI (<18.5 kg.m^-2); out-of-hours surgery; and use of ketamine or thiopental for induction. Standardised psychological impact scores at 30 days were significantly higher in awareness patients (median (IQR [range]) 15 (2.7–52.0 [2–56]) than in patients without awareness 3 (1–9 [0–64]), p = 0.010. Four patients had a provisional diagnosis of post-traumatic stress disorder. We conclude that direct postoperative questioning reveals high rates of accidental awareness during general anaesthesia for obstetric surgery, which has implications for anaesthetic practice, consent and follow-up.     

Anaesthetic considerations for fertility-sparing surgery and uterine transplantation

A number of benign and malignant gynaecological conditions can cause infertility. Advancements in assisted reproductive technologies have facilitated the rapidly evolving subspecialty of fertility preservation. Regardless of clinical indication, women now have the reproductive autonomy to make fully informed decisions regarding their future fertility. In particular, there has been an increasing interest and demand among patients and healthcare professionals for fertility-sparing surgery. Gynaecologists find themselves continually adapting surgical techniques and introducing novel procedures to facilitate this rapidly emerging field and anaesthetists need to manage the consequent physiological demands intra-operatively. Not only is it important to understand the surgical procedures now undertaken, but also the intra-operative management in an ever evolving field. This article reviews the methods of fertility-sparing surgery and also describes important anaesthetic challenges including peri-operative care for women undergoing complex fertility-sparing surgeries such as uterus transplantation.     

A randomised trial of bilateral erector spinae plane block vs. no block for thoracolumbar decompressive spinal surgery

Major spinal surgery causes significant postoperative pain. We tested the efficacy and safety of bilateral erector spinae block on quality of recovery and pain after thoracolumbar decompression. We randomly allocated 60 adults to standard care or erector spinae block. Erector spinae block improved the mean (SD) quality of recovery-15 score at 24 postoperative hours, from 119 (20) to 132 (14), an increase (95%CI) of 13 (4–22), p = 0.0044. Median (IQR [range]) comprehensive complication index was 1 (0–3 [0–5]) in the control group vs. 1 (0–1 [0–4]) after block, p = 0.4. Erector spinae block reduced mean (SD) area under the curve pain during the first 24 postoperative hours: at rest, from 78 (49) to 50 (39), p = 0.018; and on sitting, from 125 (51) to 91 (50), p = 0.009. The cumulative mean (SD) oxycodone consumption to 24 h was 27 (18) mg in the control group and 19 (26) mg after block, p = 0.20. In conclusion, erector spinae block improved recovery and reduced pain for 24 h after thoracolumbar decompression surgery.     

Using psychometric ability to improve education in ultrasound-guided regional anaesthesia: a multicentre randomised controlled trial

The learning curve for novices developing regional anaesthesia skills, such as real-time ultrasound-guided needle manipulation, may be affected by innate visuospatial ability, as this influences spatial cognition and motor co-ordination. We conducted a multinational randomised controlled trial to test if novices with low visuospatial ability would perform better at an ultrasound-guided needling task with deliberate practice training than with discovery learning. Visuospatial ability was evaluated using the mental rotations test-A. We recruited 140 medical students and randomly allocated them into low-ability control (discovery learning), low-ability intervention (received deliberate practice), high-ability control, and high-ability intervention groups. Primary outcome was the time taken to complete the needling task, and there was no significant difference between groups: median (IQR [range]) low-ability control 125 s (69–237 [43–600 s]); low-ability intervention 163 s (116–276 [44–600 s]); high-ability control 130 s (80–210 [41–384 s]); and high-ability intervention 177 s (113–285 [43–547 s]), p = 0.06. No difference was found using the global rating scale: mean (95%CI) low-ability control 53% (95%CI 46–60%); low-ability intervention 61% (95%CI 53–68%); high-ability control 63% (95%CI 56–70%); and high-ability intervention 66% (95%CI 60–72%), p = 0.05. For overall procedure pass/fail, the low-ability control group pass rate of 42% (14/33) was significantly less than the other three groups: low-ability intervention 69% (25/36); high-ability control 68% (25/37); and high-ability intervention 85% (29/34) p = 0.003. Further research is required to determine the role of visuospatial ability screening in training for ultrasound-guided needle skills.