Unwanted Blocks & Guidelines for Giving Muscle Relaxants / Reversal Agents

Dual block (or a bi-phasic block): This occasionally follows a repeated dose of suxamethonium. A single dose causes a pure depolarizing block. This is termed a phase I block. A repeated dose causes the same drug to act differently and occasionally produce a nondepolarizing block.

Mixed block: This may follow the simultaneous injection of depolarizer and nondepolarizer. The receptors may manifest both types of blocks at the same time. It is good to be aware of dual and mixed blocks. The important point is to ventilate these patients until they start breathing spontaneously again.

Guidelines for Giving Muscle Relaxants/Reversal Agents- (Table 3.1)

• Do not give to a patient whom you cannot ventilate or intubate. When administering muscle relaxants, airway equipment should be available including a bag-mask-valve device or anesthesia circuit, oral airways, oxygen, and intubating equipment.
• Allow succinylcholine to wear off before administering a nondepolarizing muscle relaxant.
• A muscle relaxant is not an anesthetic. Make sure the patient is anesthetized. Otherwise the patient may be paralyzed but awake and aware of the surgical procedure.
• Always reverse a nondepolarizing muscle relaxant, even if you think the relaxant has worn off. Patients given a muscle relaxant will frequently have residual muscle relaxation at the end of the surgical procedure.
• Before removal of the endotracheal tube ensure the patient has adequate strength exhibited by keeping the head lifted off the bed for 5 seconds, has the ability to squeeze your hand, and has the ability to follow verbal commands
• When using non depolarizing muscle relaxants remember hypothermia, antibiotics, local anesthetics, loop diuretics, magnesium, lithium, and aminoglycosides may result in a prolonged neuromuscular blockade. May result in enhanced neuromuscular blockade in patients with myasthenia gravis.
• Always monitor the effects of muscle relaxants with a peripheral nerve stimulator, if available. Indicate the site of table to be included in the description