Figure 1From: Immediate post-operative effects of tracheotomy on respiratory function during mechanical ventilationRespiratory mechanics before and after tracheotomy. Diagram of impedance (Zrs) before (continuous arrow) and immediately after (dashed arrow) tracheotomy. The corresponding pressure–flow phase angles (φ rs) are also depicted; respiratory system reactance (Xrs) and respiratory system resistance (Rrs) represent the polar coordinates of Zrs.Back to article page