Most anaesthesia inductions are the same, a bit of the white stuff, the paralysis stuff and some fast acting opioid..... and give some metaraminol if the BP drops.
But occasionally you'll get something that's incredibly high risk!
In this lecture I talk about the cardiovascularly relevant anaesthesia inductions
1) Critical cardiac disease
2) Hypovolaemic shock
3) Pulmonary hypertesion
4) Subarachnoid bleed
5) Valve lesions
6) Tamponade and
7) HOCM
1) Critical cardiac (60yo male 70kg, ischaemic cardiomyopathy EF 15%)
Key priorities
I aim to maintain preload, normal HR, normal rhythm, contractility and high afterload for coronary perfusion.
Induction meds and actual doses
Fentanyl 300mcg, Midaz 5mg, rocuronium 100mg, metaraminol running with ephedrine at hand
Reasoning
By using minimal if any Propofol, I minimize decrease in contractility and afterload. Fentanyl is typically a very cardiovascularly stable opioid that will decrease propofol requirements and minimize tachycardia on intubation.
Practically speaking, you may also have a period of bag mask ventilation where you slowly build up the volatile concentration while waiting for fentanyl to have a peak effect. I adjust metaraminol to maintain BP during this period.
2) Hypovolaemic (21yo M 70kg, MVA, abdo bleed with 3L blood loss)
Key priorities
I aim to maintain preload and afterload in a severely hypovolaemic patient
Induction meds and actual doses
Note that in a severely hypotensive patient you may need very little of anything so I’ve given ranges of agents that I have given in my experience.
Midazolam 2-5mg, ketamine 20-50mg, 100mg suxamethonium with metaraminol running and ephedrine/adrenaline ready and fluids/blood running.
Reasoning
This induction is less about avoiding tachycardia. The patient is suffering a devastating loss of preload and afterload and will need tachycardia to maintain cardiac output. I care far more about minimizing loss of preload/afterload and using judicious metaraminol to maintain a low but adequate BP.
The term hypotensive resuscitation is used, which refers to the maintenance of a low but adequate BP to simultaneously maintain vital organ perfusion without having a BP that increases blood loss and could compromise a clot that has already formed on an injured vessel. I usually aim for a systolic of 80mmHg without evidence of end organ compromise eg ischaemic ECG changes.
3) Pulmonary Hypertension (50yo F with pulm fibrosis and severe pulmonary HTN, 50kg)
Key priorities
I aim to maintain cardiac function especially right heart function with good preload, contractility and afterload whilst keeping pulmonary vascular resistance low
Induction meds and actual doses
Fentanyl 200-300mcg, Propofol 50mg, rocuronium 100mg, with metaraminol running. I would prioritize achieving good oxygenation and ventilation with minimal ventilating pressures throughout the induction to avoid rises in pulm vascular resistance.
Reasoning
I think of this situation as all about right heart function and maintaining cardiac output against a high afterload which is the pulmonary vasculature.
i.e. Make sure the right heart is happy (adequate BP for coronary perfusion with metaraminol, fluid for preload, use small quantities of hypnotics to avoid loss of contractility, and avoid tachycardia with cardiostable opioid like fentanyl.
4) Subarachnoid Bleed (50F 80kg, grade 3 Subarachnoid haemorrhage (SAH), for early clipping)
Key priorities
To avoid a increase in transmural pressure gradient (TMPG), whilst maintain cerebral oxygen delivery.
Induction meds and actual doses
Alfentanil 1500mcg, Propofol 150-200mg, suxamethonium 100g (or rocuronium 80mg) with esmolol 40mg ready for in case of tachycardia/hypertension
Reasoning
The highest mortality event with SAH, is a rebleed (mortality 50-70%). Therefore, I prioritize avoiding a high BP above avoiding transient hypotension. To do this I give reasonable doses of all agents and use suxamethonium so I am confident the patient is well paralysed prior to intubation. AND I have an agent (esmolol or Propofol) ready in case the patient does become hypertensive.
Please post any comments or questions below.
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Good luck!
Disclaimer:
This contains general information about medical conditions and treatments. The information is not advice and should not be treated as such.
The presenter makes no representations or warranties in relation to the medical information on this video.
You must not rely on the information as an alternative to assessing and managing your patient with your treating team and consultant
This document was created using a Contractology template available at www.contractology.com.
Informed consent was gained from the patient where relevant