Hello from JustAnswer.
Although a normal sat is in the mid to upper 90s, people can usually tolerate a sat down to about 90%, so sats that are 88-89% are slightly below the level that is usually tolerated without difficulty. Some people can tolerate a slightly low sat in the upper 80s, but since you are having worsening breathlessness, that would indicate that you are not tolerating it very well. So, since you are also having worsening breathlessness, the low sats are worrisome and there should be further evaluation to determine the cause.
Being overweight can contribute to lung dysfunction by limiting the ability of the chest to expand. It is also very common for chronic low sats to be due to chronic obstructive pulmonary disease, and the Ventolin may be able to help obstructive disease.. Tests of lung function, such as the lung capacity test, are the usual tests that can clarify the nature of any lung problem that is present. And it would usually be better that the evaluation be completed before elective surgery.
If I can provide any clarification, please let me know.
Yes, it is possible that any condition that affects the nerves to the respiratory muscles can impair the ability to move air in and out of the lungs and result in low sats, and this would also be assessed by the tests of lung function.
Sleep apnea will cause low sats while asleep in virtually every patient, but to affect the sat levels during the day, it is typically because of an effect of the sleep apnea on the blood pressure in the lungs and/or on heart function, and the echocardiogram is the test that would be first done to identify such changes. Since the echocardiogram showed OK, it would be appropriate to look at other causes of low sats.
You are very welcome.
Yes, it is common for tiredness to be present when the oxygen sats are low.
These symptoms would not be due to the low sats, but they could be due to the condition that is causing the low sats, but will only be known as the evaluation is done.
The key next step is the lung test, so there is no need to separately inform your doctor of the phlegm.
You are welcome.