From the Guidelines
The patient's dibucaine number of 37 indicates heterozygous atypical pseudocholinesterase deficiency, which explains the prolonged paralysis after succinylcholine administration, and therefore, succinylcholine and other ester local anesthetics should be avoided in this patient. This condition is consistent with a genetic variation that affects the metabolism of certain drugs, including succinylcholine [no relevant citation]. The dibucaine number represents the percentage inhibition of enzyme activity by dibucaine, with normal values ranging from 70-80, and homozygous atypical variants having values around 20 1. The patient's intermediate value of 37 suggests heterozygosity, meaning they have one normal and one abnormal gene for pseudocholinesterase.
When considering future anesthesia needs for this patient, it is essential to use non-depolarizing neuromuscular blocking agents like rocuronium or vecuronium instead of succinylcholine. The guidelines for reversal of residual paralysis with neostigmine, as outlined in the study 1, provide a decision algorithm for pharmacological non-depolarising neuromuscular blocking drug reversal using neostigmine. However, this is not directly relevant to the patient's condition, as the primary concern is the prolonged paralysis after succinylcholine administration due to the atypical pseudocholinesterase deficiency.
Key points to consider in the management of this patient include:
- Avoiding the use of succinylcholine and other ester local anesthetics
- Documenting the patient's condition clearly in their medical record
- Informing the patient about their genetic condition and advising them to alert all future healthcare providers
- Considering the use of a medical alert bracelet or card
- Using non-depolarizing neuromuscular blocking agents for future anesthesia needs.
From the FDA Drug Label
Reduced Plasma Cholinesterase Activity Succinylcholine should be used carefully in patients with reduced plasma cholinesterase (pseudocholinesterase) activity. The likelihood of prolonged neuromuscular block following administration of succinylcholine must be considered in such patients
The dibucaine number of 37 indicates that the patient has atypical pseudocholinesterase, which is associated with reduced plasma cholinesterase activity. This means that the patient's ability to metabolize succinylcholine is impaired, leading to a higher risk of prolonged neuromuscular block.
- Key implications:
- Prolonged paralysis after succinylcholine administration is more likely
- Careful consideration should be given to the use of succinylcholine in patients with atypical pseudocholinesterase
- Alternative neuromuscular blocking agents may be considered in patients with known or suspected atypical pseudocholinesterase 2 2
From the Research
Implications of Dibucaine Number 37
- A dibucaine number of 37 is considered normal, as it is above the typical threshold for pseudocholinesterase deficiency [ 3 ].
- However, normal dibucaine numbers do not entirely rule out the possibility of prolonged paralysis after succinylcholine administration, as seen in the case study [ 3 ].
- Pseudocholinesterase deficiency can be caused by genetic or acquired factors, and a normal dibucaine number does not guarantee normal enzyme function [ 4, 5 ].
Pseudocholinesterase Deficiency and Succinylcholine
- Pseudocholinesterase deficiency can lead to prolonged apnea and paralysis after succinylcholine administration [ 4, 6 ].
- The deficiency can be inherited or acquired, and a detailed patient history is essential to identify potential risks [ 5, 7 ].
- Alternative muscle relaxants, such as rocuronium, may be considered in patients with pseudocholinesterase deficiency or those at risk of prolonged paralysis [ 6 ].