The abnormal preoperative pulmonary function test in a patient with severe kyphoscoliosis includes:

Answer is A (Reduced RV and TLC): Kyphoscoliosis is a restrictive lung disease. There is decrease in residual volume and total lung capacity. FEV1 and FVC are propoionately decreased. Hence the ratio of FEV1 to FVC remains normal or is increased. The forced expiratory flow rate (FEF) is normal. Functional residual capacity (FRC) is decreased.