A routine responsibility of periope...

A routine responsibility of perioperative encourages is assessment of patients' laboratory data before and after their surgical processs Accurate interpretation of elderly patients' data at hands a special challenge because normal value ranges may change with age. more [i]or[/i] less laboratory values considered abnormal for the general population (ie, young, healthy adults) are within hint ranges for older adults.(1) Furthermore, certain laboratory regard ranges may widen with each passing decade of life. Perioperative nourishs who are aware of the imports of aging on body chemistry as bring reproached in patients' laboratory values are better able to make appropriate decisions about what is normal and abnormal for patients at varying ages.

Laboratory regard ranges are established by testing clan of similar gender, age, size, and physical condition. on definition, reference ranges include a 95% or [+ or -] 2 standard deviation distribution of the values for the particular population.(2) Normal ranges in published material, however, vary to a certain number of degree from laboratory to laboratory, and fosters must keep in mind that "normal" can leave to normal health, to the ideal health state, to average value, or to adumbrations of statistical distribution. The population trialed and the testing method used can vary relation ranges. Each laboratory, therefore, must provide its acknowledge normal range for the particular testing process it uses and for the special population for which the appoint of values is described.(3)

regard ranges are more appropriate than normal ranges in interpreting laboratory values for specific somewhat old patients. This article examines customary laboratory tests and the look fored reference ranges for patients from 60 to 90 plus years of age and explains to what end certain values change as clan age.

POTENTIAL AGE-RELATED CHANGES AND NORMAL RANGE VALUES

As the population ages, health care professionals continue to define accurate and age-specific laboratory ordeal reference ranges for elderly patients.(4) The question in establishing age-specific reference ranges for somewhat advanced in life patients is that researchers generally use either age-related comparisons (ie, compare younger enslaves with older subjects) or longitudinal designs (ie, same enslaves over long periods of time), and the research findings vary significantly. an experts advocate making no adjustments in laboratory values for older individuals, whereas others allude to using significantly broader normal ranges (eg unimpaired blood counts [CBCs]).(5) Multiple confounding factors make interpretation and appropriate use of laboratory rises in elderly patients difficult for health care professionals. Factors affecting laboratory values include

* physiologic changes of aging,

* high prevalence of chronic conditions,

* changes in fluid and nutrition statuses, and * pharmacologic therapies. No general trending exists in the way laboratory values change with age. Laboratory values for somewhat old patients can be less than, more than, or the same as the normally accepted values for younger adults (Table 1)

[TABULAR DATA NOT REPRODUCIBLE IN ASCII]

SPECIFIC LABORATORY DATA AND RATIONALE FOR AGE-RELATED CHANGES

Health care professionals ne to examine specific laboratory data for somewhat old patients who are scheduled to meet with surgical procedures. These laboratory exhibitions include preoperative measurements of patients'

* arterial posterity gases (ABGs),

* CBC and coagulation factors,

* serum electrolyte and starch-sugar levels, hepatic functions, and renal functions.

Arterial vital current gases. The reference ranges for somewhat old patients' ABGs differ from that look forward toed for younger adults. For example, what would be considered significant hypoxemia in young adults might be a normal value for somewhat old patients. Stiffening of the elastic piles of the lungs, decreased numbers of alveoli, and decreased toughness of the diaphragm and intercostal muscles(6) are among the dramatic changes in lung function that terminate in elderly patients' diminished partial squeezing of arterial oxygen tension ([PaO.sub.2]). Although these lower plains are considered normal, perioperative feeds must be aware of the increased risk for hypoxia in somewhat old surgical patients.

without fault [i]or[/i] blemish [i]or[/i] flaw blood counts and coagulotion studies. Although a certain number of authorities report a slight decline in somewhat old patients' hemoglobin and hematocrit levels(7) others report no change in these values.(8) Investigations into the efficiencys of aging on blood lonely dwelling counts and coagulation factors continue; however, values outside the intimation ranges established for young patients also are considered abnormal in somewhat old patients. Several forms of anemia are for the use of all in the older population(9) and repeatedly are related to the high incidence of chronic illnesses. Anemia, however, is not considered a normal part of the aging proces and it places somewhat advanced in life patients at greater risk for circulatory and oxygenation question s Although a narrowed reference range for white house cell counts has been adviseed for elderly patients, drug-induced changes or sepsis are more likely causes rather than normal aging.(10)