A system is provided for monitoring a patient on an air support system. The system comprises a capacitive sensor system (1011) having a capacitive sensor positioned at the underside of an air filled mattress, and a respiration signal processing module (1013) that receives the output of the capacitive sensor system and is configured to monitor patient respiration. Respiration is monitored by: periodically sampling the capacitive sensor system output to obtain measurements of incremental body displacement analysing a plurality of the samples to determine one or more values for parameters of patient respiratory rate and determining when one or more of the parameter values indicate abnormal respiration. A corresponding method and computer program are also provided.
