Pre-operative Pulmonary Assessment and Risk Factors for Post-operative Pulmonary Complications in Elective Abdominal Surgery in Nigeria - Ufoaroh, Chinyelu Uchenna; Ele, Prince Udegbunam; Anyabolu, Arthur Ebelenna; Enemuo, Emeka Hyacinth; Emegoakor, Chiemelu Dickson; Okoli, Chinedu Christian; Umeh, Eric Okechukwu; Anyabolu, Ernest Ndukaife (Emerging Research in Medical Sciences Vol. 4, 2020)