The physician orders the following mechanical ventilation settings for a patient: Tidal volume 800 mL, FiO2 50, Respiratory rate 14 breaths/min, Mode assist/control, and PEEP 10 cm. The patient's spontaneous respiratory rate is 22 breaths/min. What arterial blood gas abnormality may occur if the patient continues to be tachypneic at these ventilator settings?