CHEM 1406 BSA/BMI Measurement Laboratory (revised 01/03//06) BSA, Body Surface Area

Transcription

1 CHEM 1406 BSA/BMI (revised 01/03//06) BSA, Body Surface Area See pages of dosage text for equations, calculations and adult nomogram See pages of dosage calculation text for pediatric nomogram and calculations (You do not need to memorize the equations for BSA. You do need to know haw to use the equations or nonmograms. Note units of BSA. BMI, Body Mass Index From WEB Calculator page Body Mass Index = Weight(kg) / Height(m) 2 Lab Work Your height = Your weight = Blood pressure BMI (from web calculator) = BSA (from web calculator) = Conclusion from calculations/tables is: For calculations see: CDC BMI calculator, see also, Online Clinical Calculator,

2 CHEM 1406 page 2 BMI/BSA reference: Fad Diets and Obesity -- Part I: Measuring Weight in a Clinical Setting, see: from this article Body Mass Index (BMI) Also Known as 'Quetelet's Index' BMI is one of the better methods to determine who is potentially overweight or obese (Kuczmarski, Carroll, Flegal, & Troiano, 1997). It can be performed rapidly in the clinical setting just by measuring the weight and height of the individual. It is best not to have the patient self-report his or her weight and height because this lacks accuracy. However, the definition of overweight and obesity in relation to BMI may differ slightly according to different medical organizations. BMI is defined as the weight (in kilograms) divided by the square of the height in meters (kg/m 2 ). Another method of determining BMI is to take the weight of the patient in pounds and divide this number by the square of the height in inches and to multiply this value by 704 (pounds/inches 2 x 704) (Moyad, 2003). A BMI less than 25 is considered normal by the World Health Organization, while 25 to 29.9 is overweight, and 30 or greater is defined as obese. There are three classes of obesity: Class I is a BMI of 30 to 34.9 kg per m, 2 Class II is a BMI of 35 to 39.9, and Class III is a BMI equal or greater than 40. There has been a substantial increase in the prevalence of all three of these obesity classes over the past decade. Most statistics reported in the media on the percentage of overweight and obese individuals in a population actually are derived from medical studies that use the BMI as a measurement. BMI is arguably the most widely reported current measurement of obesity in medical studies. Some organizations define a BMI of 35 or 40 or more as "morbidly obese" and these are the BMI's that are generally needed in order to qualify for more serious conventional medical therapy such as gastric bypass surgery if no other treatments have been helpful. BMI does not take into account more muscular frames at different heights, as is the case with measuring crude weight (mentioned later in the article). Thus, a patient who lifts weights or engages in resistance exercises may actually experience a slight increase in BMI due to an increase in lean body mass which weighs more than fat tissue. However, patients with BMI values equal to or greater than 30 generally have an excess of adipose tissue. In a recent article, Combination Approaches to Weight Management, see: Dr. J. W. Anderson provides the following statement in the introduction. The prevalence of overweight and obesity is increasing at an alarming rate in the United States and in most other countries. [1,2] Almost two thirds of US adults are overweight, [1] and the prevalence of extreme or morbid obesity has almost tripled

3 CHEM 1406 page 3 in the last 10 years. [3] The percentage of overweight adolescents in the United States has increased 3-fold in the past 30 years. [4] Unfortunately, many obese individuals have difficulty losing weight, and most have even greater difficulty maintaining weight loss in the long term. [5,6] However, approaches that combine low-energy diets and behavioral management have been shown in studies conducted over the past 5 years to significantly improve weight l oss and maintenance. [7] Further, Dr. Anderson provides the following table for consideration. Table 2. Guidelines for Management of Overweight or Obese Individuals* Weight/Risk Assessment BMI kg/m 2 without risk factors BMI kg/m 2 with risk factors BMI kg/m 2 BMI kg/m 2 BMI kg/m 2 Preferred Treatment Meal replacements Physician counseling LED behavioral LED behavioral LED behavioral More Intense Treatment Physician counseling Community LED behavioral LED behavioral Bariatric surgery Less Intense Treatment Self-help Meal replacements Dietetic counseling Dietetic counseling Not recommended BMI > 50 kg/m 2 Bariatric surgery Bariatric surgery LED behavioral *Modified from Anderson and Wadden. [31] Behavioral s are not included because effective s are not widely available. [10] Pharmacotherapy can be used for all groups except the top group with no risk factors. LED - low-energy diet ( kcal/day)

4 CHEM 1406 page 4 Metabolic Syndrome: Dr. Scott M. Grundy (see: ) describes metabolic syndrome as presented below (2004). Metabolic syndrome is a complex disorder and an emerging clinical challenge. It is considered a "multiplex" cardiovascular risk factor, in that each component of the cluster of abnormalities is a risk factor in its own right. Introduced as Syndrome X by Reaven in 1988 [1] and also termed insulin resistance syndrome, metabolic syndrome is recognized clinically by the findings of abdominal obesity, elevated triglycerides, atherogenic dyslipidemia ie, low levels of high-density lipoprotein cholesterol (HDL-C), elevated blood pressure, high blood glucose and/or insulin resistance. Metabolic syndrome is also characterized by a prothromobotic state and a proinflammatory state. Further, Dr. Scott notes: Metabolic syndrome affects approximately 24% of the US adult population; according to the Third National Health and Nutrition Examination Survey (NHANES III) criteria, about 47 million people have metabolic syndrome, [16] including 44% of those in the >/= 50-year age group. [17] Metabolic syndrome is present in 10% of women and 15% of men with normal glucose tolerance; 42% and 64% of those with impaired fasting glucose; and 78% and 84% of those with type 2 diabetes. [18] Most patients (> 80%) with type 2 diabetes have metabolic syndrome, but the converse is not necessarily true. From:

5 CHEM 1406 page 5 The slide below indicates the risks associated with high BMI and Metabolic Syndrome. Taken from G. D. Foster, The Obesity Epidemic, Also, see: New Definition For Metabolic Syndrome Predicts Coronary Heart Disease and Type 2 Diabetes, from (July 2003) In stead of waist circumference in above table use BMI greater than 28.8 kg/m 2. For men, having four or more baseline abnormalities had a 3.7-fold increased risk for CHD and a 24-fold increased risk for diabetes. Another paper: Metabolic Syndrome and Cardiovascular Risk: Treating the Clinical Spectrum, see presents the following table of relationships among the risk factors and development of CVD.

6 CHEM 1406 page 6 Blood Pressure 1. Position the patient's arm so the anticubital fold is level with the heart. Support the patient's arm with your arm or a bedside table. 2. Center the bladder of the cuff over the brachial artery approximately 2 cm above the anticubital fold. Proper cuff size is essential to obtain an accurate reading. Be sure the index line falls between the size marks when you apply the cuff. Position the patient's arm so it is slightly flexed at the elbow. [4]

7 CHEM 1406 page 7 BLOOD PRESSURE, continued 3. Palpate the radial pulse and inflate the cuff until the pulse disappears. This is a rough estimate of the systolic pressure. [5] 4. Place the stetescope over the brachial artery. [6] 5. Inflate the cuff to 30 mmhg above the estimated systolic pressure. 6. Release the pressure slowly, no greater than 5 mmhg per second. 7. The level at which you consistently hear beats is the systolic pressure. [7] 8. Continue to lower the pressure until the sounds muffle and disappear. This is the diastolic pressure. [8] 9. Record the blood pressure as systolic over diastolic ("120/70" for example). Interpretation Higher blood pressures are normal during exertion or other stress. Systolic blood pressures below 80 may be a sign of serious illness or shock. Blood pressure should be taken in both arms on the first encounter. If there is more than 10 mmhg difference between the two arms, use the arm with the higher reading for subsequent measurements. It is frequently helpful to retake the blood pressure near the end of the visit. Earlier pressures may be higher due to the "white coat" effect. Always recheck "unexpected" blood pressures yourself. lood Pressure Classification in Adults Category Systolic Diastolic Normal <140 <90 Isolated Systolic Hypertension >140 <90 Mild Hypertension Moderate Hypertension Severe Hypertension Crisis Hypertension >210 >120 In children, pulse and blood pressure vary with the age. The following table should serve as a rough guide: Average Pulse and Blood Pressure in Normal Children Age Birth 6mo 1yr 2yr 6yr 8yr 10yr Pulse Systolic BP

8 CHEM 1406 page 8 BLOOD PRESSURE, Continued Notes 1. For more information refer to A Guide to Physical Examination and History Taking, Sixth Edition by Barbara Bates, published by Lippincott in Unlike pulse, respirations are very much under voluntary control. If you tell the patient you are counting their breaths, they may change their breathing pattern. You cannot tell someone to "breathe normally," normal breathing is involuntary. 3. With an irregular pulse, the beats counted in any 15 second period may not represent the overall rate. The longer you measure, the more these variations are averaged out. 4. Do not rely on pressures obtained using a cuff that is too small or too large. This is frequently a problem with obese or muscular adults where the regular cuff is too small. The pressure recorded will most often be 10, 20, even 50 mmhg too high! Finding a large cuff may be inconvenient, but you will also "cure" a lot of high blood pressure. 5. Maximum Cuff Pressure - When the baseline blood pressure is already known or hypertension is not suspected, it is acceptable in adults to inflate the cuff to 200 mmhg and go directly to auscultating the blood pressure. Be aware that there could be an auscultory gap (a silent interval between the true systolic and diastolic pressures). 6. Bell or Diaphragm? - Even though the Korotkoff sounds are low frequency and should be heard better with the bell, it is often difficult to apply the bell properly in the anticubital fold. For this reason, it is common practice to use the diaphragm when taking blood pressure. 7. Systolic Pressure - In situations where ausculation is not possible, you can determine systolic blood pressure by palpation alone. Deflate the cuff until you feel the radial or brachial pulse return. The pressure by auscultation would be approximately 10 mmhg higher. Record the pressure indicating it was taken by palpation (60/palp). 8. Diastolic Pressure - If there is more than 10 mmhg difference between the muffling and the disappearance of the sounds, record all three numbers (120/80/45). from

9 CHEM 1406 page 9 Blood Pressure Continued See also article, Hypertension, reference: Table 1. Classification of Blood Pressure for Adults 18 Years of Age and Older [8] Category Blood Pressure Level (mm Hg) Normal Systolic < 120 and diastolic < 80 Prehypertension Systolic or diastolic Hypertension Stage 1 Systolic or diastolic Stage 2 Systolic >/= 160 or diastolic >/= 100 Note: These categories apply to patients who are not taking antihypertensive drugs and are not acutely ill. When systolic and diastolic blood pressures fall into different categories, the higher category should be selected to classify the person's blood pressure status. Table 3. Classic Features of Essential Hypertension Onset of hypertension in the fourth or fifth decade of life Family history of hypertension BP < 180/ < 110 mm Hg at diagnosis Asymptomatic History, physical examination, and routine laboratory studies are normal (no target-organ damage at time of diagnosis) BP control achieved with lifestyle changes and one or two drugs BP control is maintained once achieved

10 CHEM 1406 page 10 Blood Pressure Continued Table 2. Proper Blood Pressure Measurement Technique Patient should refrain from smoking or caffeine ingestion for 30 min before measurement Patient should be at rest, seated in a chair with back and feet supported, for at least 5 min before measurement is taken Patient should not speak while blood pressure is being measured Patient's arm should be bare, with no tight clothing constricting the upper arm Select a proper cuff size for the arm: bladder should encircle at least 80% of arm (many adults will require a large cuff) Position patient's arm so cuff is at the level of the heart Place stethoscope bell over brachial artery Inflate cuff to occlude the pulse Deflate at rate of 2-3 mm/sec Measure systolic (first sound) and diastolic (last sound) to nearest 2 mm Hg Repeat measurement after 2 min Under special circumstances, measure blood pressure with patient in standing position Terms to Know: BSA BMI Insulin Resistance Impaired Fasting Glucose (IFG) Impaired Glucose Tolerance (IGT) Metabolic Syndrome systolic pressure Diastolic pressure See Also: The Metabolic Syndrome: Time for Critical Appraisal by Kahn, Buse, Ferrannini, And Stern;