Welcome to a new thing on the show – a section all about Rural GP anaesthesia with a shiny new, Anaesthesia Journal club. On the first episode, I am joined by my colleague from Broome Dr Alex Harris. Here is what we discuss in written form.
International consensus statement on the management of hypotension with vasopressors during caesarean section under spinal anaesthesia Kinsella et al. Anaesthesia 2017
Hypotension following spinal or combined spinal-epidural anaesthesia at caesarean section causes both maternal and fetal/neonatal adverse effects.
Hypotension is frequent and, therefore, vasopressors should be used routinely and preferably prophylactically.
a-agonist drugs are the most appropriate agents to treat or prevent hypotension following spinal anaesthesia. Although those with a small amount of-agonist activity may have the best profile(noradrenaline, metaraminol), phenylephrine is currently recommended due to the amount of supporting data. Single-dilution techniques, and/or prefilled syringes should be considered.
Left lateral uterine displacement and intravenous(i.v.) colloid pre-loading or crystalloid loading, should be used in addition to vasopressors.
The aim should be to maintain systolic arterial pressure (SAP) at≥90% baseline obtained before spinal anaesthesia and avoid a decrease to < 80% baseline. We recommend a variable rate prophylactic infusion of phenylephrine using a syringe pump. This should be started at 25–50 mcg.min immediately after the intrathecal local anaesthetic injection, and titrated to blood pressure and pulse rate. Top-up boluses may be required.
Maternal heart rate can be used as a surrogate for cardiac output if the latter is not being monitored; both tachycardia and bradycardia should be avoided.
When using an a-agonist as the first-line vasopressor, small doses of ephedrine are suitable to manage SAP < 90% of baseline combined with alow heart rate. For bradycardia with hypotension, an anticholinergic drug (glycopyrrolate or atropine) may be required. Adrenaline(epinephrine) should be used for circulatory collapse.
The use of smart pumps and double vasopressor infusions can lead to greater cardio-vascular stability than that achieved with physician-controlled infusions. NOT AVAILABLE IN RURAL!
Women with pre-eclampsia develop less hypotension after spinal anaesthesia than healthy women. Abrupt decreases in blood pressure are undesirable because of the potential for decreased uteroplacental blood flow. A prophylactic vasopressor infusion may not be required but, if used, should be started at a lower rate than for healthy women.
Women with cardiac disease should be assessed on an individual basis; some conditions are best managed with phenylephrine (an arterial constrictor without positive inotropic effect), whereas others respond best to ephedrine (producing positive inotropic and chronotropic effect).
MBRRACE-UK. Saving Lives, Improving Mothers’ Care – Lessons learned to inform maternity care from the UK and Ireland Con dential Enquiries into Maternal Deaths and Morbidity 2013–15. Oxford: National Perinatal Epidemiology Unit, University of Oxford 2017.
The specific recommendations for Anaesthesia outcomes include:
In sudden onset severe maternal shock e.g. anaphylaxis, the presence of a pulse may be an unreliable indicator of adequate cardiac output. In the absence of a recordable blood pressure or other indicators of cardiac output, the early initiation of external cardiac compressions may be life-saving. ACTION: Health professionals
In cases of massive obstetric haemorrhage, women must be adequately resuscitated and the bleeding stopped prior to extubation following general anaesthesia. Evidence of adequate resuscitation should be sought prior to extubation.
Aortocaval compression should be suspected in any supine pregnant woman who develops severe hypotension after induction of anaesthesia, even if some lateral tilt has been applied. If there is a delay in delivery, putting the woman into the left lateral position may be the only option if other manoeuvres fail or if the woman has refractory severe hypotension.
The choice of endotracheal tube for pregnant women should start at size 7.0mm and proceed to smaller tube selections if needed (size 6.0mm and 5.0mm). It is recommended that all resuscitation carts used in maternity units should include endotracheal tubes no larger than 7.0mm and include smaller sizes such as 6.0mm and 5.0mm.
AIRWAY and INTUBATION
The effect of neuromuscular blockade on the efficiency of facemask ventilation in patients difficult to facemask ventilate : a prospective trial. Soltesz et al. Anaesthesia 2017
When I was a trainee, we were taught to “check we could bag prior to giving the relaxant.” This sort of made sense – if you couldn’t ventilate via a circuit then you were going to be in hot water if you paralysed and then could not intubate…
However, that thinking comes from a time before we have all the new LMAs, rescue devices, radiation detecting devices from https://www.med-pro.net, and mandatory CICO training with surgical options being drilled. On the flipside, we know that trying to bag a patient who is light or not paralysed is tougher than bagging a flat patient… so this trial seeks to answer that question.
Single centre, prospective observational trial in a German hospital.
Patients were elective surgery patients with at least 3 predictors of difficult mask ventilation:
including – Neck radiation changes, male gender, Snoring/sleep apnea, Mallampati 3 or 4, Presence of beard 3, a BMI ≥ 30, age > 57, limited jaw protrusion
Induced with Remi infusion, fentanyl and propofol then attempted facemask ventilation with a Guedel in place.
They used a 2 hand technique and set the ventilator on PC on 13 cm / 3cm PEEP. They could adjust PIP to get to target tidal volume.
Considered a failed face-mask ventilation if they couldn’t get at least a 2 ml/kg Tv despite > 30 cm PIP.
They then gave Rocuronium 0.6mg/kg and set the NMT to repeat TOF and watched what happened to the tidal volumes as the roc soaked in…
Basically in the patients who were “difficult” to bag initially the tidal volumes were low to start – in the 2 – 3 ml/kg range around 200ml. In the “easy” group they achieved about double that prior to paralysis. However, after a few minutes, once the roc was effective and the TOF faded they were all getting good Tv around 600ml.
Conclusion: NMB assists face mask ventilation in predicted difficult patients. The authors then go onto say that it is still important to check for difficult or impossible mask ventilation prior to giving NMB…
My friend did a simulation study looking at this and found that trainee anaesthetists almost universally proceeded to give NMB despite what they found at test attempt!
Anyway there was a “response letter” published by Dr Priebe ; in Anaesthesia Volume 73, Issue 3 March 2018 Pages 389–390.
He argues that the authors should stick to their guns and state that if NMB is so good for facilitating face mask ventilation then why bother documenting it prior to paralysis. Quote: If muscle relaxation almost uniformly facilitates FMV, what would be such clinically-relevant “useful information”?
He also rails against the concept of using Sux in the scenario where ventilation is difficult as it will still land you in at least 10 minutes of CICO if the tube is impassable.
Thoughts: I think the documentation of difficult “UNPARALYSED FACE MASK VENTILATION” is useful – mainly for the future
When you are extubating – this information can help you decide how awake they need to be before you pull the tube?
FOr future Anaesthetists reading the notes – can be reassuring to know if it is hard or tough. MAybe the plan needs to change for future operations?
What do you do?
SUGGAMADEX – THE UPS and DOWNS
Can sugammadex save a patient in a simulated ‘cannot intubate, cannot ventilate’ situation? Bisschops et al in Anaesthesia 2010
This is a simulation study from a centre in the Netherlands. 18 teams of Anaesthetists, nurses and trainees of varying experience were put through a standardised “CICO” simulation in a mock theatre.
The patient was a 113 kg 40-year-old woman. Induced with sufentanil, propofol and 100 mg rocuronium. The team were given a standardised instruction to enter the CICO situation where they were told to continue bagging and “reverse the rocuronium as fast as possible”. The timer started as the rescue team entered the door.
The sugammadex was located in a store fridge about 50m from the theatre. It was in 200 mg ampoules only.
The outcome measured was the time to administer the dose of sugammadex, they also recorded errors in dose, delivery etc. hEre is the telling slide from the results:
The more expereinced teasm were a little faster – although the fastest team also gave a woefully low dose! They took 4 and a half minutes to give 300 mg (the recommended dose would be ~ 1800 mg for weight). Scarily there were a lot of calculation errors and simple slip-ups – eg. looking for “bridion” by the brand name on the shelf. One team almost gave another dose of Roc in the kerfuffle.
In reality, a 7 minute time to administer, followed by 2 minutes to work would be roughly the same time it takes Sux to wear off!.
The actual research team had a crack at the Sim and they took 2.17 minutes, which still would mean 4.5 minutes to achieve reversal.
if you are using Roc with a plan to use Sugammadex, you probably should precalculate the dose and write it on a checklist somewhere.
Have the stuff in the airway or anaesthesia trolley – not in the hallway. This is not the time to send a team member on a goose hunt!
This scenario needs to be drilled as a team to make it faster and avoid errors.
Recovery characteristics of patients receiving either sugammadex or neostigmine and glycopyrrolate for reversal of neuromuscular block: a randomised controlled trial Mike Paech et al from KEMH. Anaesthesia 2018
In this RCT performed at KEMH in Perth WA sugammadex and neostigmine were compared in a blinded fashion.
PAtients were elective day case women undergoing laparoscopic surgery of less than 1 hour under Roc NMB.
Unfortunately only 304 got analysed where 360 were required for power calculation due to surgical changes etc. Then a few were lost to follow up and 21 protocol violations means we cannot achieve our desired outcomes
Induced with fentanyl, propofol and onto Sevo. Roc 0.6 – 0.8mg/kg. All got paracetamol and IV dexamethasone 4mg.
The primary outcome was the rate of PONV in first 6 hours post op. It was NO DIFFERENT 49 vs 51%. Late PONV, use of antiemetics were no different.
The Sugammadex group did have less diplopia and dry mouth though as a secondary endpoint.
KETAMINE DOSES AND SUCH
Predictors of Emesis and Recovery Agitation With Emergency Department Ketamine Sedation: An Individual-Patient Data Meta-Analysis of 8,282 Children Green et al, Annals of Emergency Medicine Aug 2009
This was a huge data dredge of studies looking at adverse effects of ketamine in the ED. They looked at individual patient level data in 8282 kids. Not an RCT, but a lot of power to gauge the best way to use special K.
Summary of key findings. In order to minimise nausea, vomiting and emergence agitation.
The highest risk age was around 10 – 14 years
IMI ketamine was worse than IV for pretty much everything
The optimal IMI dose was 3.0 – 3.5 mg/kg, which is less than the traditional 4 mg/kg
OPtimal IV dose to avoid side effects was probably 1.5 – 2 mg/kg. Above 2.5 mg/kg things got uglier
Overall the rates of serious bad recovery agitation were around 1- 2% which is what we should tell people
Optimal Dosing of IV Ketamine for Procedural Sedation in Children in the Emergency Department – A Randomized Controlled Trial Kannikeswaran et al, AJEM March 2016
This smaller (n=171) RCT looked at the dosing of ketamine for ED sedation. They compared 1.0, 1.5 and 2.0 mg/ kg as a starting IV bolus. The outcomes they were looking at included: the need to redose, adequacy of procedural sedation and the adverse events.
There were a lot of problems with the randomisation and protocol in this trial.
The kids who got 1 mg/kg 8/50 needed another dose and 10/50 had inadequate sedation. This was much more than the higher doses.
the rates of vomiting were ~ 10, 12.5 and 20% as the doses went up
more kids in the 1 mg/kg group experienced recall of the events.
IN summary 1.5 mg/kg seems to be the lowest starting dose to give for IV ketamine if you believe this study. Read in combination with the big trail above that seems to be consistent across both trials. 1.0 is probably not enough.
GASTRIC ULTRASOUND STUFF (WARNING: Not for Practice just yet!)
I am a bit obsessed with a few things. One is bedside US, another is PAediatric sedation… so this gastric US stuff appeals to my early-adopter mindset. I think this is interesting and that in the future may be part of our practice. Specifically, in small hospitals where GP gas docs are often forced to choose between an ED sedation and “calling in the theatre crew” to do a formal RSI for emergent problems eg. the badly fractured arm.
TO quote me: “I think the question should not be ‘how long is the kid fasted’ but rather ‘what is in their stomach'” Because that is what we really want to know when deciding about the risk of aspiration.
Basically, the idea is that you can scan the antrum of the stomach in both the supine and R lateral decubitus positions and make an assessment of the volume of fluid/solids in the stomach. It is actually really easy to do!
This is still a new concept and has been controversial. There are a number of small cases series in kids, adults and pregnant women. The best data we have thus far is this paper:
Ultrasound assessment of gastric volume in the fasted pediatric patient undergoing upper gastrointestinal endoscopy: development of a predictive model using endoscopically suctioned volume by Spencer et al, Pediatric Anaesthesia 2015
In this observational trial of 100 kids undergoing gastroscopy, they measured the cross-sectional area of the antrum the two positions and then suctioned out the stomach under direct vision to get an accurate “true” gastric content to use as a gold standard.
There was a pretty good agreement between the two, with a nice linear relationship observed
They could also use a qualitative 3 tier grading score to correlate with volume to allow faster, more user-friendly assessment at the bedside.
The inter-rater agreement between clinicians using the qualitative scoring system was excellent kappa = 0.88
Take home points:
Probably not ready for prime time
IN the future we should be able to integrate this information into our clinical decision algorithm to make paediatric anaesthesia safer
If you want to play around with this – do so in a SAFE manner. I would suggest only use the information you get from a gastric ultrasound to push you to a more conservative anaesthetic than you were originally planning to use. eg. if the plan was ED sedation, the scan shows a hamburger in the stomach – maybe opt for an RSI.
A negative scan, showing empty stomach is reassuring, but do what you would have done on clinical assessment for now
More data in the future hopefully
OK, that is it.
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I am a GP working in Broome, NW of Western Australia. I work as a hospital DMO (District Med Officer) doing Emergency, Anaesthestics, some Obstetrics and a lot of miscellaneous primary care. Also on the web as @broomedocs | + Casey Parker | Contact