Bests & Worsts Reviews from Amazon

I do not recommend this for anyone! This did not work at all, read below for the full story. Product being returned! I had a heart attack two weeks ago which led to open heart surgery. I am home and wanted an accurate method of checking my blood oxygen levels quickly and often. With over 154000 reviews it was hard to deny that by all respects this was a good purchase. It arrived on time today (there is no beating Amazon delivery), and packaged well. After unboxing the unit I put the batteries in and tried it out. I put it on my finger and the unit turned on, but no readings came up and it didn't register any signal. I read though the directions figuring I missed something and followed all of the instructions... Nothing. The unit did not recognize any of my fingers, ever, after many tries. So, again feeling it may be me- with slightly chilled fingers or not enough blood supply, we tried the unit on all of my wife's fingers, it registered on only one when holding the unit just perfect. (my wife is healthy with warm fingers) It took just over a minute to get a reading on the one finger and it came up with 73% blood oxygen. We tried again, same amount of time to get a reading, result was 76%. Absolutely ridiculous. There are many online articles that talk about how vendors manipulate ratings on shopping sites, and by no means am I an expert in this area, but it feels like that is what is happening here. 1540000 reviews at 4.5 positive suggests a product which is the best of the best, heck-at that rate even hospitals should switch to these!! And then, read some of the 5 star reviews and so many of them have the same verbiage, almost like 'Joe' from the east side of the US and 'Sam' who lives on the west side of the US are best friends and were on the phone when they submitted their reviews. It doesn't take an investigator to see a pattern in the majority of reviews and to feel suspicious of the reviews. I apologize for the lengthy review, but this has me ticked off. Final statement - this company appears to be willing to put others at risk, and if the thing about reviews is correct steps are then taken to manipulate the system without thought of the potential harm to others. Thank you for taking the time to read this, I do appreciate it.