Is a diastolic reading of 78 high or low?

Thanks for your question.
A blood pressure reading of 131/76 is pronounced "131 over 76." You may also see it written colloquially as 131/76 bp.
In a blood pressure reading of 131/76, 131 is called the systolic number and 76 is called the diastolic number. Systolic refers to the part of the cardiac cycle in which the heart contracts and pumps blood from the chambers into the arteries, and diastolic refers to the part of the cardiac cycle in which the heart relaxes and allows the chambers to fill with blood. You may also hear the systolic and diastolic numbers referred to as the top number and the bottom number.
Systolic and diastolic readings are measured in mmHg, which is a unit of pressure equal to the pressure that can support a column of mercury 1 millimeter high. Hg is the chemical symbol for mercury. For a blood pressure reading of 131/76, you would pronounce it "131 over 76 millimeters of mercury

Diastolic pressure (the lower number) measures pressure in the arteries between heart beats. Blood pressure between 120/80 and 140/90 is borderline high (prehypertension), while blood pressure above 140/90 defines high blood pressure.

That's highish, the diastolic (lower) reading being the most significant. However a single spot reading does not tell the whole story as BP does vary quite a bit throught the day. See your doctor for the next step, as exercise levels, weight, family history, and other factors all go into it.

Mayo clinic says: Most doctors consider chronically low blood pressure too low only if it causes noticeable symptoms. (Such as dizziness, especially when first standing up). Some experts define low blood pressure as readings lower than 90 mm Hg systolic or 60 mm Hg diastolic - you need to have only one number in the low range for your blood pressure to be considered lower than normal. I hope this helps!

That paper coined a new term, "isolated diastolic hypotension," which refers to a low diastolic blood pressure (less than 60 mm Hg) and a normal systolic pressure (above 100 mm Hg). Older adults who fit those conditions are at increased risk for developing new-onset heart failure, the researchers found.17 May 2015

UAB - The UAB Mix - Diastolic blood pressure: How low is too low?

https://www.uab.edu/mix/stories/diastolic-blood-pressure-how-low-is-too-low Low diastolic pressure for what reason Google Search

First age is not a factor.
60 mm Hg or less is generally considered low blood pressure
This is usually caused by congestive heart failure, and as far as increasing the pressure it would be a question for your Cardiologist.

110/95 Blood Pressure
Is 110/95 Good Blood Pressure or High Blood Pressure?

There are two parts or two separate numbers referred to as blood pressure: Systolic/Diastolic. If the blood pressure is 110/95 (110 over 95), it means that the systolic pressure is 110 and the diastolic pressure is 95.

110/95 blood pressure can also be read as 110/95 mm Hg, or 110/95 millimeters of mercury. The 110 mm Hg Systolic refers to the pressure in the arteries when the heart beats, and the 95 mm Hg Diastolic is the pressure in the arteries between heartbeats.

When determining if 110/95 is a good blood pressure, we looked at the American Heart Association's blood pressure chart.

Blood Pressure Systolic Diastolic Normal Less than 120 Less than 80 Prehypertension 120 - 139 80 - 89 High Blood Pressure
(Hypertension) Stage 1 140 - 159 90 - 99 High Blood Pressure
(Hypertension) Stage 2 160 or higher 100 or higher Hypertensive Crisis
(Emergency care needed) Higher than 180 Higher than 110
For 110/95 to be good, both numbers must fit into the "normal" category above. Otherwise, it will fall into other categories of High Blood Pressure.

Systolic reading of 110 is in the Normal range.
Diastolic reading of 95 is in High Blood Pressure (Hypertension) Stage 1 range.
Therefore, 110/95 is High Blood Pressure (Hypertension Stage 1).

Normally, the 160, 200 & 240 are the systolic (top) reading of the blood pressure. Again, that's under normal conditions. But, even so, the 200 & 240 are extremely high. The diastolic is the bottom reading. With a systolic reading of 200 or 240, the diastolic reading is usually very high too. In which case, it would indicate the person has hypertension (abnormally high blood pressure), which can be a serious situation.

The nornal blood pressure for a healthy individual is 120 to 140 over 80 or less. Age, weight, smoker or nonsmoker and other health issues, can affect this normal reading one way or the other.

As an EMT for over 25 years, I would be concerned if I had a patient with a blood pressure reading of 200/120 (200 over 120). And even more so, if their blood pressure reading was 240/120 or higher.

If you have had or are having readings on the high side as I described, I would recommend that you consult your personal doctor as soon as possible.

Your Blood Pressure may be to high for the reading. Try to adjust the cuff and restart. Are you sure it is diastolic reading and not systolic?