The diaphragm is the primary respiratory muscle, and its dysfunction predisposes patients to respiratory failure. Diaphragm function can be assessed by ultrasound measurement - Diaphragmatic Thickening Fraction (DTF). Respiratory viral infections (including SARS-CoV-2) can cause diaphragm dysfunction. Our case series follows three patients infected with COVID-19 pneumonia. Bedside diaphragmatic ultrasound assessments measuring DTF were trended over patient's hospital course until clinical improvement (i.e., off oxygen) or worsening (i.e., intubation). Our preliminary results suggest a correlation between DTF trends and respiratory status in patients requiring 100% oxygen. Further studies are required to assess DTF and its possible correlation to respiratory failure.