anbr3

I am a 32 year old male, 6'0 tall, and 225 pounds (BMI of 31). I had an at home sleep study done in 2016, to which my doctor said "your study is pretty normal so no need to investigate further". The doctor has since left the practice and I decided this week to pick up a bunch of reports from all my doctors over the years just to have for my records. The sleep study report said:

a total of 14 respiratory events were observed. 0 obstructive apnea’s, 5 central apnea’s, 0 mixed apnea’s and 9 hypos was for a normal AHI of 1.9 events/hr.

The average saturation was 75%. Patient was at or below 88% oximetry for 19% of the study time. The lowest saturation was 89%.

Highest heart rate 91bpm. Lowest was 47bpm. Average was 59bpm.

Impressions: no evidence of sleep disorder led breathing. Significant desaturations noted.

I am very confused by the saturation part of the study. How can my average saturation be 75% yet my lowest saturation be 89%? Also, why was this conveyed to me as a normal report. I am very confused about all of this.