i am a nursing student in Malaysia. Sometimes i also fail to assess the blood pressure,especially weak patient. There are several problem we may face when taking blood pressure. It may be the quality of the stethoscope itself, the way we check the blood pressure, the condition of the patient or oneself. Some patient BP sound is hard to detect due to body weakness.So, it is better that we use the automatic BP set to check the weak patient. The patient BP from 120/80 change to 150/100 because the patient may be anxious especially you rechecked their blood pressure,he/she may be in fear that what is wrong with their blood pressure so increase in blood pressure. Another reason is, my senior told me that if we keep pumping the cuff in the same patient, it may cause their BP to increase.And, may be the patient has a history of hypertension,and the medication that they taking has loose their effect as the time passed,so BP suddenly become high,especially when patient is on Nifedipine, the Nifedipine can only last in patient body for 8hours,if exceeds that time, the BP will shoot up,the condition get worse if they miss a dose of Nifedipine.I had an experience that checking BP using automatic set was different using manual set, the patient only had stage 1 hypertension, but the automatic BP set showed the patient BP was 177/110,then i use manual BP set to recheck,it then showed 128/80. It really take times to practice in listening the BP sound using manual BP set. Practice make perfect. Perhaps my idea is helpful.