In a child with tetralogy of Fallot with fever and diarrhea, which of the following is the surest sign of a cyanotic spell?

Ans: B: Absence of murmurExplanation:(Ref: Nelson 20Ie p2212; Ghai 8/e p422)During cyanotic spell, temporary disappearance or a decrease in intensity of the systolic murmur is usual as flow across the right ventricular outflow tract diminishes.Paroxysmal hypercyanotic attacks (hypoxic, "blue," or "tet" spells) are a paicular problem during the 1st 2 years of life.The infant becomes hyperpneic and restless, cyanosis increases, gasping respirations ensue, and syncope may follow.Most frequently in morning on initially awakening or after episodes of vigorous crying.