Final answer:
The only absolute contraindication for use of a pneumatic antishock garment (MAST) is onset of sustained muscular contraction that cannot be let go for the duration of shock.
Step-by-step explanation:
The only absolute contraindication for use of a pneumatic antishock garment (MAST) is onset of sustained muscular contraction that cannot be let go for the duration of shock. This is because the contraction of chest muscles may lead to difficulty breathing during shock. Other contraindications include threshold of sensation, maximum harmless current, and onset of pain.