IPA: /æpˈnoʊəl/
KK: /æpˈnoʊəl/
Relating to or marked by a temporary cessation of breathing.
The patient was diagnosed with an apnoeal condition that required immediate attention.
Apnoeal is derived from "apnoea" (from Greek "apnoia", meaning without breath) and the suffix "-al" (meaning pertaining to). The term "apnoeal" refers to something that is related to or characterized by the absence of breath.
Think of 'without breath' ('apnoea') to remember that 'apnoeal' means pertaining to the absence of breath.