Total body weight

The intracellular fluid (ICF) represents the water contained within cells and is rich in electrolytes such as potassium, magnesium, phosphates, and proteins. O The ICF is approximately two-thirds of TBW regardless of gender. For a 70-kg man, this would mean that the TBW is 42 L and the ICF is approximately 28 L. For a 70-kg woman, these values would be 35 L and 24 L, respectively. Note that ICF represents approximately 40% of total body weight in men and approximately 33% of total body weight in women. 

Total body weight gain was decreased in pigs fed hydrogen sulfide at a dose level of 6.7 mg/kg/day for 105 days (Wetterau et al. 1964). No effects on body weight gain were noted at doses of 1.5 or 3.1 mg/kg/day. 

Skeletal muscle comprises the largest group of tissues in the human body and accounts for up to 40% of total body weight. This type of muscle, which is innervated by the somatic nervous system, is under voluntary control. Skeletal muscle performs many important functions in the body, including ... 

The kidneys receive a disproportionate fraction of cardiac output. Although the combined weight of the kidneys accounts for less than 1% of total body weight, these organs receive 20 to 25% of the cardiac output. This magnitude of blood flow, which is in profound excess to their metabolic needs, enables them to carry out their multiple homeostatic functions more efficiently. Assuming a resting cardiac output of 5 1/min, the renal blood flow (RBF) is approximately 1.1 1/min. 

Data are not corrected for physical decay and are listed in approximate order of decreasing radioactivity concentrations. h Tissue weights were normalized to a total body weight of 10 kg. c L.N. indicates Lymph Nodes. 

The volume of distribution of many drugs is significantly increased or decreased in patients with CKD. Changes result from altered protein or tissue binding, or pathophysiologic alterations in body composition (e.g., fractional contribution of total body water to total body weight). 

Chloroform absorption depends on the concentration in inhaled air, the duration of exposure, the blood/air partition coefficient, the solubility in various tissues, and the state of physical activity which influences the ventilation rate and cardiac output. Pulmonary absorption of chloroform is also influenced by total body weight and total fat content, with uptake and storage in adipose tissue increasing with excess body weight and obesity. 

Function begins to return as soon as nutritional support is introduced, even before any tissue gain, suggesting an immediate and direct effect on cellular function. Skeletal and respiratory muscle function deteriorates steeply after a loss of 20% of body protein stores (equivalent to 15% total body weight loss) and improves by 10-20% within the first few days of nutritional support. 

In obese patients (more than 20% above ideal total body weight), determine dosage on the basis of lean body weight. Reduce dose in elderly or debilitated patients. 

Maternal dosing (IV) - During labor and delivery, administer IV zidovudine at 2 mg/kg (total body weight) over 1 hour followed by a continuous IV infusion of 1 mg/kg/h (total body weight) until clamping of the umbilical cord. 

Obesity is not exactly a gastrointestinal disease but is a condition characterized by an unusually high percentage of body fat - normally 15-18% in males and 20-26% in young females. Definitions vary but obesity is commonly defined as having more than 30% of total body weight composed of fat. 

Poorly perfused tissues (adipose tissue, connective tissue, and bone) require hours to come into equilibrium with plasma drug concentrations (Fig. 25.1). Since the accumulation of anesthetic in body fat is relatively small soon after its IV administration, it is common clinical practice to calculate drug dosage on the basis of lean body mass rather than on total body weight. Thus, an obese patient may receive the same dose of IV anesthetic as a patient of normal body weight. 

Preterm infants have much less fat than full-term infants. Total body fat in preterm infants is about 1% of total body weight, compared with 15% in full-term neonates. Therefore, organs that generally accumulate high concentrations of lipid-soluble drugs in adults and older children may accumulate smaller amounts of these agents in less mature infants. 

Bone is a so-called composite material, i.e. it combines two properties which are rarely present in one material namely it is extremely strong and light in weight. For example bone is 4 times as strong as cement and the skeleton of a person of 66 kg only weighs about 9 kg, which is merely 14% of the total body weight. 

If the weight of an adult s skeleton is represented as g grams, his or her total body weight can be represented as... 

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