Q: Which muscles are prone to get more affected in Critical illness polyneuropathy (CIP) and critical illness myopathy (CIM)?

Answer: The hip and shoulder muscles

Critical illness polyneuropathy (CIP) and critical illness myopathy (CIM) is a clinical diagnosis though some work up may assist to confirm it. Clinical clues are critically ill patients  who are immobilized and have progressive, generalized, symmetric muscle weakness. Setting of CIP/CIM may delay extubation time by 1-2 weeks.

Reference:

Johnson, KL (Apr–Jun 2007). "Neuromuscular complications in the intensive care unit: critical illness polyneuromyopathy.". AACN Advanced Critical Care 18 (2): 167–80; quiz 181–2.

Hermans, Greet; De Jonghe, Bernard; Bruyninckx, Frans; Berghe, Greet (2008). "Clinical review: Critical illness polyneuropathy and myopathy". Critical Care 12 (6): 238.