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Posts tagged Obstetrics.

Does a GA CS increase PPD risk? Plus LMA studies & COVID vaccine optimism

GA caesarean section & post-partum depression

This large study (Guglielminotti 2020) of 428,204 New York caesarean section records (2006-2013), including 34,356 general anaesthetics (8%), investigated the association between mode of anaesthesia and post-partum depression (PPD). Other studies have shown an association between caesarean section (emergency > elective) and PPD. (Sun 2021, Xu 2017, and others), though this is the first to look specifically at general anaesthesia as a PPD risk factor.

Guglielminotti and Li found that general anaesthesia increased the odds of severe PPD by 54% (aOR 1.54, 1.21-1.95), and suicidal ideation by a massive 91% (aOR 1.91, 1.12-3.25), though not a significant increase in anxiety or PTSD.

The researchers discuss many potential causative factors, particularly known associations between GA CS & poor pain control, and subsequent pain & PPD – while also acknowledging the obvious potential for confounders. Of note patients receiving GA were older, more often non-Caucasian, had more co-morbidities, neonatal complexity, and lower socio-economic levels – also all independently associated with PPD risk.

In order to quantify the potential confounding contribution of emergency vs elective status, the researchers employed the novel E value:

To assess the impact of emergent cesarean delivery on our results, we calculated the E value associated with the aOR for the risk of PPD and suicidality. This relatively new metric takes into consideration 2 associations: (1) that between the confounder (emergent cesarean delivery) and the outcome (PPD); and (2) the association between the confounder (emergent cesarean delivery) and the exposure (general anesthesia).

An E value of 1.7 for the unmeasured confounder emergent cesarean delivery indicates that to explain away the association between general anesthesia and depression, either: (1) emergent cesarean delivery increases the risk of depression by at least 70%; or (2) emergent cesarean delivery is at least 70% more prevalent among general anesthesia than among neuraxial anesthesia. Either association is clinically plausible.

Keep it in perspective...

We already know that general anaesthesia for CS is suboptimal: it compromises both maternal experience and safety, but it should (hopefully) only ever be a chosen mode of anaesthesia when there is a true contraindication to regional anaesthesia – even at the modestly-high 8% GA rate among this New York cohort.

Looking at it from the other end, bear in mind that the modestly-faster time-to-incision for GA over regional is also of questionable neonatal benefit.

The take-home:

Just another reason to avoid GA CS when possible – but you already knew that, right?

"...general anesthesia is a potentially modifiable risk factor for PPD. This finding provides further supporting evidence favoring neuraxial over general anesthesia in cesarean delivery whenever possible."

Supraglottic airway training and manikins

Interesting prospective simulation & equipment study by way of the University of Freiburg. Schmutz et al. investigated how effective five different second generation supraglottic airway devices (SADs) performed in two common airway manikins: the TruCorp AirSim® and the crowd favourite, Laerdal's Resusci Anne® Airway Trainer™.

While ventilation was achieved in all SAD-manikin combinations, the Resusci Anne® Airway Trainer™ was associated with better and more consistent performance for SAD position, participant subjective assessment and ease of gastric tube insertion for most of the SADs. The TruCorp AirSim® did however achieve better leak pressures across most of the SADs (LMA® Supreme™, Ambu® AuraGain™, i-gel®, KOO™-SGA & LTS-D™).

But then, what are the implications for airway simulation training? The researchers correctly note that:

The most important quality of a manikin is the ability to simulate the real-world conditions and thus to give the trainee an authentic feedback.

The bottom line for SAD manikins?

While considering how manikin choice and SAD availability match with your aims for simulation training, the bigger picture is that the primary goal of any manikin-SAD coupling is real-life fidelity – and for that reason, participant subjective assessment is king. And so in this study at least, the Resusci Anne® Airway Trainer™ wins.

Read on for head rotation with LMAs & COVID vaccine persistence...

Old, new and current trends in obstetric anaesthesia

Some interesting research on common and not-so-common obstetric anaesthesia topics: both new trends and continuing trends, as well as a cautionary medicolegal reminder.

Supraglottic airways for GA Caesarean?

Metodiev & Mushambi's editorial looks at the attitude shift among obstetric anaesthesiologists to more favourably consider the LMA or SGA for Caesarean section under GA.

They review the evidence for aspiration risk, particularly noting what we learned from NAP4 (2011) but contrast this with many studies showing safety of SGAs for GA CS (over 8,000 patients in total, with Halaseah 2010 investigating 3,000 alone!). Interesting, but before we get too excited keep in mind that the populations studied are likely very different from parturients you may typically look after.

They conclude:

"...there is insufficient evidence to recommend universal or selective replacement of tracheal tubes with SGA devices during general anaesthesia for Caesarean delivery. Aspiration remains the main concern." – Metodiev & Mushambi (2020)

Cautionary reminders of neuraxial injury

McCombe & Bogod reviewed 21 years of obstetric anaesthetic medicolegal claims, noting common themes around consent, types of nerve injury, and recognition and management failures.

Not only is neurological injury the second most common reason for obstetric anaesthetic claims (behind inadequately managed pain during Caesarean section), it carries the highest average claim cost.

The review is full of many useful observations, but Reynold's 2000 advice regarding interspace level choice for spinal access is by far the most important: always access the intrathecal space at the lowest possible level, and "...the L2/3 interspace should not be an option."

McCombe & Bogod spend some time exploring the variability of cord termination level, individual variability of the intercristal line, and the inaccuracy of anaesthetist interspace level estimation. Well worth reading the whole review.

Read on for CS vasopressor choices & heavy bupivacaine alternatives...

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