“Blood alone moves the wheels of history” — Benito Mussolini
We often assume what we were always taught must always be true. But what if it’s not? What if we make efforts to go beyond dogma and do things differently; understand things differently? July’s issue of Anaesthesia might just encourage readers to do that by publishing work on anaemia, laryngoscopy grading, and more.
Haemoglobin is the vehicle that helps to keep us alive, and surgery is an insult that may remove that vehicle. But do we know enough about pre-operative anaemia and iron deficiency to optimise the vehicle? In this month’s issue of Anaesthesia, Muñoz and colleagues presented a retrospective cohort study of five centres in Spain addressing precisely this question. They assessed data from more than 3000 patients undergoing a range of surgical procedures in which the underlying pathology predisposes to anaemia, has an expected risk of > 500 ml blood loss, and/or has a > 10% transfusion risk. They found that one third of patients were anaemic (Hb < 130 g.l-1), of which two-thirds had either iron deficiency or iron sequestration, and, perhaps unsurprisingly, two thirds of anaemic patients were women. Notably, 62% of anaemic patients had absolute iron deficiency, but half of non-anaemic patients were iron deficient or had low iron stores. They took this information and incorporated the recently published game-changing international consensus statement on anaemia management to suggest management for different scenarios pertaining to iron deficiency (Fig. 1).
Figure 1. Patients’ classification, according to pre-operative haemoglobin levels and iron status, and *suggested actions to be taken, as per a recent international consensus statement. Absolute iron deficiency defined by ferritin < 30 μm.l−1 or ferritin 30–100 μm.l−1, plus transferrin saturation < 20% and/or C-reactive protein > 5 mg.l−1; iron sequestration defined by ferritin > 100 μm.l−1, plus transferrin saturation < 20% and/or C-reactive protein > 5 mg.l−1; low iron stores defined by ferritin 30–100 μm.l−1, plus transferrin saturation > 20%.
This data was accompanied by a thought-provoking editorial by Butcher et al, who looked at the findings from a different perspective. Butcher et al. suggest that, as women generally have smaller circulating blood volumes than men, the same peri-operative blood loss would have a significantly larger effect on the former than the latter. Compounding this, we have long accepted that anaemia in women is defined by a lower Hb than that for men, and therefore females are more likely to require transfusion. This is a curious paradox, one which has received little consideration in the past. However, Butcher and colleagues point to Muñoz’s data as a demonstration that, if target Hb concentrations are the same between men and women, the latter are far more likely to be anaemic. It is imperative, therefore, that we readjust our age-old targets, and consider changing the arbitrary cut-offs of to 130 g.l-1, irrespective of sex. This novel thinking is likely to drive a significant amount of research in the future, and could perhaps increase the safety of patient management, no matter the gender.
O’Loughlin et al have assessed a question that many haven’t asked: what scoring system should to describe glottic visualisation at videolaryngoscopy? The authors compared the age-old Cormack and Lehane score (published in Anaesthesia just 35 years ago), the percentage of glottic opening (POGO) score, and the authors’ very own Fremantle score. As a quick reminder, the POGO score is an estimate of the percentage of the glottic inlet that is seen on laryngoscopy, and the Freemantle score is the three-component composite describing the view, the ease of intubation and the device use for intubation. The authors showed 20 videolaryngoscopic intubation videos to 74 critical care physicians, and compared accuracy with an expert panel assessment, as well as assessing intra- and inter-rater reliability. They found that the POGO and Fremantle score are superior to the Cormack and Lehane score in the outcomes assessed. However, O’Loughlin et al go one step further and suggest that, because their Freemantle score provides additional information about the ease of intubation, this should be the go-to scoring system. Of course, few anaesthetists in the UK apply this scoring system, and ultimately the reason to describe the view at laryngoscopy is for communication. The next question should be: does the Fremantle score improve communication enough to drop the tried and tested Cormak and Lehane score?
This issue of the Journal next takes us to a simple, yet novel method for determining the location of epidural needle placement using continues pressure wave-form monitoring. By attaching extension tubing attached to a pressure transducer to epidural needles, pulsatile waveforms synchronised with heart rate represent epidural placement (fig. 2). 93% of patients who had effective epidural block also had a clear epidural pressure waveform on transduction. This technique thus provides, in the authors words, a ‘simple adjunct to loss-of-resistance for identification of needle placement.’ Of course, can you imagine the challenge in routinely locating a transducer set, appropriate monitor, whilst meeting 30 minute to attendance for epidural placement limit that many departments work towards? Neither can McKendry and Muchatuta, who question the necessity for this technique in the obstetric environment, and suggest that not only should other techniques be explored, but one should always consider that problems with regional anaesthesia techniques might be addressed by ‘looking for the cause on the proximal end of the needle.’ So let’s work out how best to improve our technique!
Figure 2. An example of a typical pulsatile waveform, synchronous with the arterial pressure trace, recorded from a correctly located epidural needle. Top trace–intra-arterial pressure; middle trace (labelled CVP)–epidural space pressure; bottom trace–pulse oximeter waveform.
Novelty is abound, and Leong et al have presented a vital signs-controlled remifentanil PCA technique. By programming a PCA device to act based on feedback from vital signs, the authors demonstrated a reduction in adverse events. Scholten et al published an exciting systematic review of novel techniques to assist with needle tip identification during ultrasound-guided procedures. They summarise the data on needle guides (including lasers!), needle tip design, 3D and 4D ultrasound, magnetism, robots and more. The challenges of regional anaesthesia might be overcome by the plethora of technological advances. Feng, Liao and Huang demonstrated that internal iliac artery balloon catheters might not be as effective for placenta accreta than we once thought; Flubacher et al demonstrated what we probably know about the efficacy of ondansetron as an anti-emetic; and Brix and colleagues found that day surgery does not always mean single day care episodes.
That was our whistlestop tour of the July issue of the Journal, but much more can be found between the covers that is sure to excite, entice and enlighten all who read it!
Trainee Fellow, Anaesthesia
Post art: Kariem El-Boghdadly