Based on chiefs description, is his trustworthiness as a narrator compromised?

Chief might come across unreliable as a narrator in that he is apt to completely lose track of reality at the slightest trigger. He normally does not dream because of the pills that plunge him into heavy slumbers. Now, however, with the opportunity to dream, his subconscious is unleashed, and while this nightmare is not so different from those of sane people, his reaction suggests that he is in another fog. Perhaps he senses that he has reached a critical point where he either must fight back to lucidity or surrender to the fate of Blastic. McMurphy will be pivotal in helping Chief Bromden choose to start recovering. Still, he doesn't really have a personal agenda so many of his comments seem objective even lacking criticism when it is warranted.