Abstract: A plethysmograph system is provided for monitoring neonates in an intensive care setting. The system includes a base and a pivotably attached lid which together define an air-tight chamber in which an infant can be positioned. The lid is mounted to the base so that it may be rotated between a position in which it is seated upon the base to a storage position directly beneath the base. The lid includes a peripheral gasket which is made from hollow tubing. The base also includes a gasket which is engageable by the lid gasket. The base gasket is made from substantially softer material than the lid gasket. First and second sealing members are mounted to the base and lid, respectively, for providing an air-tight seal about IV tubes and the like, extending from outside the chamber to an infant within the chamber. Each sealing member includes a number of channels for receiving such tubes. Each channel includes a set of parallel, deformable walls extending completely across the channels.