Hi.
It depends on your project requirements. What type of data do you need to store? How often do you need to monitor data? 
Regards,
Sara

measuring pulse rate, blood oxygen saturation, respiration rate, blood pressure
, body temperature, PRV/HRV parameters, and physical activities, and can transfer
essential health parameters to the cloud-based personal health monitoring systems

Hi.
If you’re looking to store data over time, a time-series database like influxDB can be a great option.
If you need more flexibility you can use a MySQL database.
Or, if you need user management and login options, maybe Firebase can be a better option. Depending on your project, you might also use more than one type of database.
Regards,
Sara

What about Thingspeak?

It can also be an option. 
But, in my opinion, the free plan is very limited if you want to save more than three different parameters and multiple patients.
However, it’s very easy to get started with Thingspeak. So, you can try it out and see if it actually suits your requirements.
Regards,
Sara