I had a ~ 30 wkr, good BP, good sat, minimal vent support, but hr ~ 100-110. Did not make any sense. Kept complaining to the docs--no response from them. Plenty other customers much sicker. They were concerned, but busy.
Our policy is < 34 weeks, low HR limit set at 100. If > 34 weeks low HR limit set at 80. We have to get an order for a term quiet baby who keeps dipping just below 80. And then the order would probably be to 75, especially if baby is pink and well-saturated.