This study's aim was to model and simulate a wireless sensor network and to propose a two-step sensitivity analysis for a targeted application related to home cardiac monitoring. After an initial phase of research to design the appropriate network simulator implemented in Omnet++, 13 simulation parameters have been selected to test their criticality. The sensitivity analysis relies on two consecutive steps carried out in Matlab: a screening phase (Plackett-Burman design) and a global sensitivity analysis (Space-fiiling design). Two output variables are considered: the number of packets received by the sink and the reception cache hit percentage. Four critical simulation parameters have been identified: the message length, bit rate, the background noise power and the energy detection of the radio receiver. In perspective, this sensitivity analysis will be included as a component of a Quality-by-Design approach of network development. This contribution is the early stage result obtained by Y. Kolasa during his MsC and PhD thesis (begun end of 2017) [2].