Electrolyte disorders in the elderly

Aspectos gerais da avaliação pré-operatória do paciente idoso cirúrgico

As intervenções cirúrgicas em pacientes idosos têm se tornado cada vez mais frequentes, uma vez que esta população vem apresentando crescimento em número significativo nas últimas décadas e consequentemente expondo-se por mais tempo às morbidades de resolução cirúrgica. Apesar de um número importante de idosos apresentarem envelhecimento saudável e tolerarem o ato cirúrgico sem muitas intercorrências, sabe-se também que a morbi-motalidade que envolve a operação é mais frequente no indivíduo idoso e requer muito mais cuidado naquele com comorbidades. O presente trabalho se propõe a rever alguns aspectos que merecem ser mais cuidadosamente observados, porque envolvem modificações morfológicas e funcionais do organismo senescente, que guardam relação com o aumento da morbidade e da mortalidade em todo o período peri-operatório. A avaliação pré-operatória, portanto, deve pautar-se em exame criterioso de toda história clínica do paciente com vistas a estabelecer medidas de prevenção de eventos mórbidos, evitar iatrogenias, estabelecer critérios que alertem para um maior risco e desenvolver enfoque multidisciplinar.

Aging affects choroidal proteins involved in CSF production in Sprague-Dawley rats

Aging is currently associated with progressive declines of cerebral functions. From these, a decreased resistance to dehydration suggested alteration in choroidal control of brain homeostasis and reduced cerebrospinal fluid (CSF) production in old subjects. In the present study, choroid plexuses of 20-month old Sprague-Dawley rats were compared with those of 3- and 10-month old rats. Using ultrastructure analysis and immunodetection of ezrin, a protein associating cytoskeleton to membranes, we showed that progressive loss of microvilli and strong decrease in apical ezrin are evident in 20-month old rats. Using immunolabeling and confocal microscopy, we found reduction in expression of two choroidal proteins, carbonic anhydrase II and aquaporin 1, involved in CSF secretion. In addition, we confirmed previous studies indicating that choroidal Na,K-ATPase decreased with age. In situ hybridization analyses showed that mRNA levels for Na,K-ATPase and aquaporin 1 were significantly lowered in choroid plexus of old rats. These findings are consistent with a reduced secretory activity in choroid plexus and suggest that massive disorders could affect choroidal CSF production in aged rats.

Dehydration and death during febrile episodes in the nursing home

OBJECTIVE

To determine the incidence of early hypernatremic dehydration among residents of a nursing home care unit (NHCU) presenting with significant febrile episodes (FE).

DESIGN

Prospective cohort analytic study. FE were defined as temperature (T) > 100 degrees F oral (o) or 101 degrees F rectal (r) for > or = 24 hours.

SETTING

NHCU in a Veterans Administration hospital.

PATIENTS

A total of 130 residents of the NHCU were monitored for FE during a 4-month study period.

MAIN OUTCOME MEASURES

Blood urea nitrogen (BUN)/creatinine (Cr) (abnormal > or = 25) and serum sodium (Na)(abnormal > or = 146 mmol/L) were drawn within 24-48 hours of the onset of all FE; documentation of impaired oral intake (OI) by staff; necessity of transfer to acute medical wards and mortality were recorded.

RESULTS

There were 48 FE among 42 residents (39 M, 3 F; mean age 75 +/- 11.3). Maximum recorded T during the FE ranged from 100.1 degrees F-102.2 degrees F o and 101.2 degrees F-105.3 degrees F r. Laboratory values were available for 40/48 FE. Twenty-three percent (9/40) had elevated BUN/Cr ratios, 25% (10/40) had elevated serum Na, and 12.5% (5/40) had both. In patients noted to have impaired OI (n = 11) as documented by staff, increased serum Na or BUN/Cr ratio was observed in 82% (9/11). A random control group of 37 nonacutely ill, nonfebrile NHCU residents (33 M, 4 F; mean age 75 +/- 10.1) having routine annual laboratory tests revealed only 1 resident (age 95) with an elevated Na of 146 and BUN/Cr ratio of 26 and 1 resident with an increased BUN/Cr ratio of 28. None of the controls had any staff documentation of impaired OI. Of the 5 deaths in the febrile group with laboratory data (total deaths = 6; 14%), 100% had either elevated serum Na and/or elevated BUN/Cr ratios, and 80% (4/5) had both. Comparing the febrile group with controls, BUN/Cr ratios were found to be significantly elevated in the febrile group (P < 0.05). Serum sodium values were also significantly elevated in the febrile group (P < 0.01).

CONCLUSIONS

Staff documentation of impaired OI was highly associated with either elevated serum Na or increased BUN/Cr ratios. These data show that many older NHCU patients with significant fevers often have early impaired OI and laboratory evidence of dehydration. These data indicate that staff should institute appropriate monitoring for dehydration at the time of earliest detection of fever in this population.

Clinical indicators of dehydration severity in elderly patients

STUDY OBJECTIVE

To determine which of the signs and symptoms of dehydration obtainable from patient history and physical examination in the emergency department are most useful in assessing the severity of dehydration in elderly patients.

DESIGN

Prospective, correlational study.

SETTING

Two university teaching hospitals.

PATIENTS

Fifty-five patients aged 60 or older presenting to the emergency department with suspected dehydration were studied.

MEASUREMENTS AND MAIN RESULTS

In the emergency department, patients were evaluated by a standardized history and physical examination that included assessment of 38 signs and symptoms commonly attributed to dehydration. The relationships between the presence and intensity of these putative dehydration indicators and an independent rating of dehydration severity based on a comprehensive review of the medical record were evaluated. Also evaluated were the relationships between these dehydration indicators and patient age. Indicators that correlated best with dehydration severity but were unrelated to patient age included: tongue dryness (P less than 0.001), longitudinal tongue furrows (P less than 0.001), dryness of the mucous membranes of the mouth (P less than 0.001), upper body muscle weakness (P less than 0.001), confusion (P less than 0.001), speech difficulty (P less than 0.01), and sunkenness of eyes (P less than 0.01). Other indicators had only weak associations with dehydration severity or were also related to age. Patient thirst was unrelated to dehydration severity.

CONCLUSIONS

A set of signs and symptoms related to dehydration severity in elderly patients has been identified. These indicators may be more useful for evaluation of dehydration severity in the emergency department than other commonly used indicators.

Urinary diluting capacity in elderly diabetic subjects

Urinary concentrating ability declines with normal human aging but diluting capacity has been less well studied as a function of age. We studied free water clearance (CH2O) in a group of Type II diabetic patients, aged 47 to 70 years. Conventional water load testing in sulfonylurea-treated diabetic patients revealed preservation of diluting capacity (ability to achieve Uosm less than 100 mOsm/kg) in subjects greater than 60 years of age. Tolazamide permitted expression of normal CH2O; chlorpropamide administration predictably reduced CH2O relative to tolazamide by 58% in subjects greater than 60 years. Free water clearance (CH2O) and glomerular filtration rate (GFR) were comparable in elderly subjects (greater than 60 years) and those less than or equal to 60 years. Normal CH2O in these diabetic patients was explained by persistently normal GFR in the study group. Osmolar clearance (Cosm) was insignificantly lower in diabetics greater than 60 years. Thus, a fall in CH2O in elderly diabetic patients is not a factor contributing to clinical hypoosmolar states encountered in this population.