Which arterial blood gas result is most indicative that the intubated and mechanically ventilated patient is ready to have the ventilator rate weaned?

The patient complains of heart palpitations. The nurse understands which lab result is responsible for the patient's symptoms?

During a well-child visit for the 4-month-old child, the nurse palpates hard nodules where each rib joins the sternum. The nurse reports this finding to the provider and requests which lab studies for this patient? Select all that apply.