Background

Several labs have used home-made or custom-built plethysmograph devices to identify respiratory failure in genetically modified neonatal mice (Nsegbe et al., 2004; Crone et al., 2012). However, for researchers who are novices in this field and want to investigate the cause of neonatal lethality in mice, a commercial whole-body plethysmograph (WBP, Buxco system, DSI) is a reasonable choice.

When we first set up this system to monitor respirations of P0 mice, the respiratory activities in C57BL/6 newborns were most of the time undetectable until mice reached 3 days old. Because the WBP measures the pressure changes within the animal chamber that are due to inspired air humidified and heated by an animal’s lung during breathing, increasing the detection sensitivity of this device was the only way to monitor respiration of C57BL/6 neonates before P3.

In this protocol, we share our experience in modifying this system to reliably detect rhythmic respiration in C57BL/6 neonatal pups as early as P1 and possibly P0. Once the recorded traces are obtained, several parameters calculated by the FinePointe software are useful for exploring respiratory abnormalities in mice who do not die of cyanosis due to severe respiratory failure right after birth (Lai et al., 2016).