A 50-year-old male patient presents with acute respiratory distress due to acute exacerbation of chronic obstructive pulmonary disease (COPD). The patient is alert and oriented but experiencing labored breathing with an SpO2 of 85% on room air. Non-Invasive Ventilation (NIV) is initiated. Which of the following clinical signs indicates that NIV is effective for this patient?
Improved SpO2 to greater than 90%
Use of accessory muscles
Development of bradycardia
Absent breath sounds