Oops

SalineI drew up some saline from the drawer in the birth suite to flush the cannula before putting in an epidural.

When I checked again I found that the drawer was filled with a mixture of saline and lignocaine.

 

 

 

 

 

 

Lignocaine.jpg

BT_RA1.3  Discuss the pharmacology of local anaesthetic agents including:
· Mechanisms of action
· Comparative pharmacology of different agents
· Toxicity
· Use of adjuvant agents to enhance the quality or extend duration of block
· Pharmacokinetics of drugs administered in the epidural and subarachnoid space

 

 

 

 

 

If I had given the 20mls as an intravenous bolus:

T/F The best volume of distribution to estimate the peak plasma concentration would be V area.

T/F The most likely arrhythmia to occur would be Ventricular Fibrillation

T/F Seizures occur at a plasma concentration of 5µg/ml

T/F Cardiac arrhythmias occur at a plasma concentration of around 2 times that which cause seizures

T/F Lignocaine causes dose dependent negative inotropy

Bonus questions:

Why is bupivacaine more cardiotoxic than lignocaine?

Is ropivacaine less toxic than bupivacaine?

Why should you treat the seizures?

2017.1 : SAQ 12

Discuss the physiological consequences of total spinal anaesthesia caused by intrathecal administration of 20ml of  2% lignocaine at the L3/4 level. (Do not include management)

BT_RA 1.2

A great question to demonstrate understanding of the physiological consequences of neuraxial blockade. The effects can all be deduced from your knowledge of physiology and pharmacology. However there is a most excellent article in AIC(1974) in which TI Evans, a Victorian anaesthetist, administered 30-40ml of 1% lignocaine intrathecally at the lumbar level in 100 patients. He proceeded to tilt the table 10 to 15 degrees head down and administer oxygen until vocal cord paralysis and unconsciousness developed and he intubated them. There were excellent conditions for abdominal surgery. The curious can access this work online through the college library, as a bonus the same issue (2) has quite a nice article on electrical safety as well.

This will cause bradycardia TRUE/FALSE

The patient will have dilated gut TRUE/FALSE

The patient will become hyperthermic TRUE/FALSE

The patient will have dilated pupils TRUE/FALSE

The patient will be unconscious TRUE/FALSE

2017.1 : SAQ 7

Discuss the factors affecting duration of action of a local anaesthetic block to a major peripheral nerve.

BT_RA 1.3

Lot of patient interest out there in you knowing this.

Less lipid soluble drugs have a longer duration of action  TRUE/FALSE

Low protein binding causes a longer duration of action  TRUE/FALSE

Large molecules have a longer duration of action  TRUE/FALSE

Less vascular areas have a longer duration of action  TRUE/FALSE

In an elderly patient there will be a longer duration of action  TRUE/FALSE

Local Anaesthetics Part 2

A bit more on toxicity of local anaesthetics today.

BT_RA1.3  Discuss the pharmacology of local anaesthetic agents including:
· Mechanisms of action
· Comparative pharmacology of different agents
· Toxicity
· Use of adjuvant agents to enhance the quality or extend duration of block
· Pharmacokinetics of drugs administered in the epidural and subarachnoid space

Early excitatory signs of neurotoxicity are due to activation of excitatory interneurons TRUE/FALSE

High foetal plasma concentrations of local anesthetic are a result of higher α1-acid glycoprotein concentrations in the foetus TRUE/FALSE

Methaemaglobinaemia from prilocaine toxicity results in a right shift of the oxygen haemaglobin dissociation curve TRUE/FALSE

All local anesthetics exert dose-dependent negative inotropic action on cardiac muscle TRUE/FALSE

The CNS effects of local anesthetics may contribute to the generation of arrhythmias TRUE/FALSE

Local Anaesthetics

Sometimes whilst studying, I felt like I needed some Novocaine for the soul

Today, local anaesthetics….

BT_RA 1.3 Discuss the pharmacology of local anaesthetic agents including:
· Mechanisms of action
· Comparative pharmacology of different agents
· Toxicity
· Use of adjuvant agents to enhance the quality or extend duration of block
· Pharmacokinetics of drugs administered in the epidural and subarachnoid space

Duration of action of a local anaesthetic is primarily determined by the pKa of the agent  TRUE/FALSE

Increasing the dose of local anaesthetic will increase the duration of action TRUE/FALSE

Benzocaine is only suited to topical anaesthesia due to its lipophilicity TRUE/FALSE

All local anaesthetics EXCEPT ropivicaine cause vasodilation TRUE/FALSE

Adding bicarbonate to a local anaesthetic solution hastens the onset of action TRUE/FALSE