Bates’ Visual Guide to Physical Examination

Volume 5: 5.4 Vital Signs Video Transcript

Narrator: Now you are ready to measure the vital signs which include blood pressure, heart rate, respiratory rate and temperature. Note that recent evidence suggests that home and ambulatory blood pressure measurements are more accurate than manual measurements taken in the office. These studies propose that automated office blood pressure devices that take and average the results of five or more readings help eliminate observer error and minimize whitecoat hypertension caused by patient anxiety.

Make sure the examining room is quiet and comfortably warm, and before assessing the patient’s blood pressure take the steps to make sure the measurement will be accurate. Ask the patient to avoid drinking caffeinated beverages or smoking for 30 minutes and to rest for at least 5 minutes before the blood pressure is taken.

Check to make sure the selected arm is free of clothing. There should be no arteriovenous fistula is for dialysis, scarring from prior brachial artery cut downs or signs of lymphedema. Palpate the brachial artery to confirm that it has a viable pulse. Position the arm so that the brachial artery at the antecubital crease is at the heart level, roughly level with the fourth interspace at its junction with the sternum. The patient’s arm should be supported at the mid chest level.

To measure blood pressure accurately, you must choose a cuff of appropriate size. Cuffs that are too wide or too narrow make it false readings. Here are some guidelines to help you select the correct blood pressure cuff. The width of the inflatable bladder of the cuff should be about 40% of upper arm circumference, which is about 12-14 cm in the average adult. The length of the inflatable bladder should be about 80% of upper arm circumference, which is almost long enough to encircle the arm. All blood pressure devices, whether aneroid, electronic or hybrid should be routinely calibrated for accuracy using international protocols. To accurately measure the blood pressure, center the inflatable bladder over the brachial artery with the arm at heart level. The lower border of the cuff should be about 2.5 cm above the antecubital crease. Secure the cuff snugly and position the patient’s arms so that it is slightly flexed at the elbow.

When using an aneroid instrument, hold the dial so that it faces you directly. To determine how high to raise the cuff pressure, first estimate the systolic pressure by palpation. As you feel the radial artery with the fingers of one hand, rapidly and sleep it off until the radial pulse disappears. Read this pressure on the manometer and add 30 mmHg to it. Using this target for subsequent installations prevents discomfort from unnecessarily high cuff pressures. It also avoids the occasional error caused by an auscultatory gap, a silent interval that may be present between the systolic and the diastolic pressures. Deflate the cuff promptly and wait 15-30 seconds. Now place the bell of a stethoscope lightly over the brachial artery, taking care to make an air seal with its full rent. Because the sounds to be heard; that is, the Korotkoff sounds, are relatively low in pitch, they are generally heard better with the bell.

In play the cuff rapidly again to the level just determined and then deflate it slowly at a rate of about 2-3 mmHg per second. Note the level at which you hear the sounds of at least two consecutive beats. This is the systolic pressure. Continue to lower the pressure slowly until the sounds become muffled and then disappear. To confirm the disappearance of sounds, listen as the pressure falls another 10-20 mm. The disappearance point, usually only a few millimeters of mercury below the muffling point, provides the best estimate of true diastolic pressure in adults.

Read both the systolic and diastolic levels to the nearest 2 mmHg. Wait two or more minutes and repeat the entire sequence. Average your readings. If the first two readings differ by more than 5 mmHg, take additional readings. Avoid slow or repetitive inflations of the cuff because the resulting venous congestion can cause false readings. Blood pressure should be taken in both arms at least once. Normally there may be a difference and pressure of 5 mmHg and sometimes up to 10 mm. Subsequent readings should be taken on the arm with a higher pressure. Averaging several blood pressure measurement is best. Differences of more than 10 mmHg between the arms raised concerns of subclavian steel and aortic dissection.

In 2003, the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure recommended using the mean of two or more properly measured blood pressure readings taken on two or more office visits for diagnosis of hypertension.

For adults, the committee has defined 4 levels of systolic and diastolic hypertension: normal, pre-hypertension, Stage 1 hypertension, and Stage 2 hypertension. Note that either component may be high. When the systolic and diastolic levels fall in different categories, you should use the higher category. If you read low levels of blood pressure, you should interpret this reading and the light of past readings and the patient’s clinical state.

If indicated, assess orthostatic hypotension, common in older adults, by measuring blood pressure and heart rate in two positions; supine, after the patient is resting from 3-10 minutes, and then within 3 minutes after the patient stands up. Orthostatic hypotension is a drop in systolic blood pressure of 20 mm or greater, or in diastolic blood pressure of 10 mm or greater within 3 minutes of standing, or a rise in heart rate of more than 20 beats per minute.

If there are weak or inaudible Korotkoff sounds, check the placement of your stethoscope and whether you have full skin contact with the bell. Also consider the possibility of venous engorgement of the patient’s arm from repeated inflations of the cuff or even the possibility of shock. To intensify Korotkoff sounds, try raising the patient’s arm before and while you inflate the cuff, then lower the arm and determine blood pressure, or inflate the cuff and ask the patient to make a fist several times and then determine the blood pressure.

For the obese arm, use a cuff 15 cm in width or consider using a five cuff wrapped around the forearm and then assessing the radial pulse. When assessing the heart rate (or HR) the radial pulse is commonly used. With the pads of index and middle fingers, compress the radial artery until you detect a maximal pulsation. If the rhythm is regular and the rate seems normal, count the rate for 30 seconds and multiply by 2. If the rate is unusually fast or slow, however, count it for 60 seconds. The range of normal is 50-90 beats per minute. To begin your assessment of rhythm, feel the radial pulse. If there are any irregularities, check the rhythm again by listening with your stethoscope at the cardiac apex. Premature beats may not be detected peripherally, and the heart rate can be seriously underestimated. Is the rhythm regular or irregular?

If irregular, try to identify a pattern by asking:

Always check an electrocardiogram if the rhythm is irregular to identify which type of rhythm is present.

Next, observe the rate, rhythm, depth and effort of breathing. Count the number of respirations in one minute either by visual inspection or by subtly listening over the patient’s trachea with your stethoscope during your examination of the head and neck or chest. Normally, adults take approximately 20 breaths per minute in a quiet, regular pattern. An occasional science normal. Check to see if the expiration is prolonged, suggesting COPD.

For oral temperatures, choose either a glass or electronic thermometer. When using a glass thermometer, shake the thermometer down to 35°C, or 96°F or below. Then insert it under the tongue. Instruct the patient to close both lips and wait 3-5 minutes. Then read the thermometer, reinsert it for 1 minute and read it again. If the temperature continues to rise, repeat the procedure until the reading remain stable. Note that hot or cold liquids or even smoking can alter the temperature reading, so in these cases it is best to delay measuring the temperature for 10-15 minutes.

Electronic thermometers are increasingly replacing glass thermometers. To use this device, carefully place the disposable cover over the probe. Insert the thermometer under the tongue and ask the patient to close both lips and then watch closely for the digital readout. An accurate temperature recording usually takes about 10 seconds. Most patients prefer oral to rectal temperatures. However, taking oral temperatures is not recommended if patients are unconscious, restless or unable to close their mouths. In these cases, rectal temperatures are advised.

For a rectal temperature, ask the patient to lie on one side with the hip flexed. Lubricate the tip of the thermometer. Insert the thermometer about 3-4 cm, or 1.5 inches into the anal canal in a direction pointing to the umbilicus. Remove it after the recommended time period and then read. As opposed to this electronic thermometer, the process with a glass thermometer is the same, although you must wait 3 minutes to read the results.

Taking the tympanic membrane temperature is increasingly common practice and is quick, safe and reliable if performed properly. Make sure the external auditory canal is free of cerumen, which lowers the temperature readings. Position the probe in the canal so that the infrared beam is aimed at the tympanic membrane, otherwise the measurement will be invalid. Weight 2-3 seconds until the digital reading appears. This method measures core body temperature, which is higher than the normal oral temperature by approximately 0.8°C or 1.4°F. Normal oral temperature in adults fluctuates considerably with the average usually clouded as 37°C or 98.6°F. It may fall as low as 35.8°C in the morning hours or rise as high as 37.3°C in the late afternoon or evening.

Rectal temperatures are higher than oral temperatures by an average of 0.4 for 0.5°C or 0.7 to 0.9°F. This difference, too, is quite variable. In contrast, axillary temperatures are lower than oral temperatures by approximately 1°, take 5-10 minutes to register and are generally considered less accurate than other measurements.