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Biomedical subjects

K L Minaker

Publications and source records attributed to K L Minaker.

At least 37 records · Page 2Linked to original sources
PubMed1994

Indices of dehydration among frail nursing home patients: highly variable but stable over time.

OBJECTIVE: To determine changes in standard laboratory measures of dehydration among residents of a nursing home care unit (NHCU) over a 6-month period. DESIGN: A prospective cohort analytic study. SETTING: A 130-bed NHCU in a Department of Veterans Affairs Hospital. PATIENTS: Fifteen infirm but stable male residents (mean age 77 years; range (R) 62-93) on one ward of the NHCU. MAIN OUTCOME MEASURES: We studied prospectively for 6 months the serum osmolality (osm), serum sodium (Na), blood urea nitrogen/creatinine (BUN/Cr) ratios and weight (wt) for 15 patients of the NHCU. None of the patients was acutely ill during the study period or exhibited clinical signs of dehydration. RESULTS: Mean serum osm at baseline: 291.6 mOsm/kg (R 278 to 300); 3 months: 291.5 mOsm/kg (R 276 to 301); 6 months: 291.3 mOsm/kg (R 283-300) were all similar. Forty percent (6/15) of patients had at least one high normal/elevated reading (> or = 295 mOsm/kg) during the study. Three patients (20%) had readings of > or = 300 mOsm/kg, but none of these patients had either concurrent increased serum Na (> or = 146 mmole/L) or BUN/Cr ratios (> or = 25). Mean serum Na at baseline: 143.0 mmole/L (R 139-148); 3 months: 142.1 mmole/L (R 138-149); 6 months: 142.9 mmole/L (R 137-150) were all similar. Sixty percent (9/15) of the patients maintained normal (nl) serum Na levels throughout the study. The relationship between the change in serum Na and serum osm levels from baseline to 6 months was not significant (r = 0.242). BUN/Cr ratios ranged from 12-34 over the study period with 3 of 15 patients (20%) demonstrating elevated ratios consistently throughout the study without clinical evidence of dehydration. Only two patients had both high nl/elevated serum osm and elevated serum Na, although both had nl BUN/Cr ratios. Neither of these patients was thought by staff to be clinically dehydrated. Analysis of variance (ANOVA) indicated none of the laboratory measures changed significantly over time (serum osm: F(2,28) < 1; Na: F(2,28) < 1; BUN/Cr: F(2,28) < 1). There was no significant change in weight between the baseline and six month readings. CONCLUSIONS: These data suggest that in the presence of clinical stability, long-term care residents may have a serum osm in the high normal/elevated range without overt clinical evidence of dehydration, an accompanying elevated Na, or BUN/Cr ratio. This may indicate a different central osm setting for these residents as the serum osm appeared to be stable for each resident over time. These data also suggest that measures of serum osm, Na, and BUN/Cr in the long-term care setting may accurately predict future laboratory values in an individual patient if baseline values are drawn when the patient is not acutely ill.

Aged↗
PubMed1994

Constipation: assessment and management in an institutionalized elderly population.

OBJECTIVES: To examine prescribing and utilization patterns of laxatives, stool softeners, and enemas in a large, long-term care facility, to compare self-reports of constipation with specific, bowel-related symptoms in residents of this facility, and to examine concordance between bowel symptoms reported by residents and the assessments of the nursing staff. DESIGN: Cross-sectional study. SETTING AND SUBJECTS: All individuals residing in an academically oriented long-term care facility in the United States for at least 1 month (n = 694). MEASUREMENTS: Clinical, functional, and medication data were abstracted from the medical and nursing records. Individual interviews regarding bowel-related symptoms were conducted with all able participants (n = 456 (66%)) and their respective primary nurses, and concordance was determined. The study definition of symptom-specific constipation was no more than 2 bowel movements per week and/or straining on more than 1 in 4 bowel movements. RESULTS: Fifty percent (n = 367) of all residents used at least 1 daily laxative, stool softener or enema during a 1-month study period. Over half of all laxative users (n = 200) took more than 60 doses per month. Stool softeners were most commonly prescribed, followed by saline laxatives, stimulant laxatives, hyperosmolar laxatives, and bulk laxatives. Forty-seven percent (n = 213) of the 456 interview responders reported constipation ("self-reporters"), but only 62% of self-reporters met the study criteria for symptom-specific constipation. Concordance between resident's and nurse's report regarding specific bowel symptoms was only fair to slight (kappa 0.12-0.38). Self-reporters of constipation took almost twice as many laxatives, stool softeners, and enemas as residents who did not report constipation.

Aged↗
PubMed1994

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.

Adult↗
PubMed1993

Reporting of age data in clinical trials of arthritis. Deficiencies and solutions.

OBJECTIVE: We studied recent nonsteroidal anti-inflammatory drug (NSAID) randomized control trials of arthritis to identify the age and number of older people (> or = 65 years) and to document the way information on age was presented. We hypothesized that older people, who are most likely to take NSAIDs are underrepresented and underreported. STUDY SELECTION AND DATA EXTRACTION: All NSAID articles (n = 1008) in MEDLINE between September 1987 and May 1990 were identified. Eighty-three trials employing NSAIDs in a randomized control trial of arthritis reported in 73 articles were identified and studied in detail for age-related information. RESULTS: A total of 9664 subjects with a female-to-male ratio of 2.3:1 were enrolled. Forty-four trials studied osteoarthritis (53.0%), 37 studied rheumatoid arthritis (44.6%), and two studied both conditions (2.4%). More than half of the studies reviewed included people 65 years of age or older, only 207 people in this older age group could be identified (2.1%). While there was inclusion of the 'young-old' (65 to 74 years of age), only 14 of the 9664 people studied were between 75 and 84 years of age, and no one 85 years or older could be identified. The inclusion of the young-old is documented by the weighted mean age that ranged from 59.6 to 64.9 years for patients with osteoarthritis (mean, 62.9; SD, 1.67) and from 47.4 to 53.0 years (mean, 49.9; SD, 2.16) for those with rheumatoid arthritis. CONCLUSION: We demonstrate that older people, who represent a high proportion of the population treated with NSAIDs in practice, are generally omitted from drug trials. Recommendations designed to improve the reporting of age information to make clinical trials more informative and applicable to older people are presented.

Aged↗
PubMed1993

Sequential evaluation of islet cell responses to glucose in the transplanted pancreas in humans.

We evaluated the hormonal and metabolic responses of denervated pancreas allografts in nine volunteers 3 to 12 months after the transplant (initial) and again 1 year later (follow-up). Eight of the patients received simultaneous pancreas-kidney transplants. The glucose clamp technique was used to create a square wave of hyperglycemia 5.5 mmol/L above the basal glucose level for 2 hours. A biphasic insulin response was evident in each subject, both initially and at follow-up. The initial plasma insulin response was fourfold higher in patients with pancreas-kidney transplants than in normal volunteers. However, the plasma insulin response of the patients with pancreas-kidney transplants at the follow-up study was more similar to that of the normal controls. The plasma glucagon levels were elevated in follow-up clamp studies. Hepatic glucose production and glucose disposal were similar in both studies. At the follow-up examination only, GLUT4, the major insulin-sensitive glucose transporter, was measured in muscle homogenates by immunoblotting. GLUT4 levels in the patients with pancreas-kidney transplants were only 55% as abundant as in normal volunteers. This may be due, in part, to immunosuppressive therapy or to persistent, albeit reduced, levels of hyperinsulinemia even 2 years after transplantation. We concluded that, despite systemic drainage of the pancreas and immunosuppressive therapy, pancreatic insulin secretion, peripheral insulin levels, and muscle insulin responsiveness are restored toward normal levels approximately 2 years after the transplant.

Adult↗
PubMed1993

Risk assessment for pressure ulcers: an adaptation of the National Pressure Ulcer Advisory Panel risk factors to spinal cord injured patients.

To estimate risk factors for pressure ulcers, we developed quantitative definitions for each of the nine general areas of risk outlined by the 1989 National Pressure Ulcer Advisory Panel (NPUAP) and evaluated each of these factors in a group of spinal cord injured patients by means of a retrospective chart review at a spinal cord injury referral center serving the New England area. All patients (n = 364) admitted to the spinal cord injury service between January 1, 1989 and December 31, 1990 were studied. We identified a pressure ulcer in 81 of 364 patients (22.3 percent). In the univariate analyses, pressure ulcers were associated with Frankel groups A to B with an odds ratio (OR) of 5.7 (95 percent confidence interval 2.8 to 11.9), low albumin with an OR of 4.9 (95 percent confidence interval 2.8 to 8.6), low hemoglobin with an OR of 2.5 (95 percent confidence interval 1.5 to 4.1), age > or = 60 years with an OR of 1.9 (95 percent confidence interval 1.2 to 3.2) and three independent measures of co-morbidity: Cumulative Illness Rating Scale (CIRS) with an OR of 3.7 (95 percent confidence interval 2.1 to 6.3), Charlson Index with an OR of 2.2 (95 percent confidence interval 1.3 to 3.8), and International Classification of Diseases, Ninth Revision, Clinical Modification count with an OR of 4.2 (95 percent confidence interval 2.4 to 7.2). In the logistic regression model, low albumin, CIRS and Frankel grade A to B and history of pressure ulcers were predictors.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Constipation in the elderly.

OBJECTIVE: To explore the distinction between true clinical constipation and the subjective complaint of constipation in elderly people and to review the pathophysiology, symptoms, diagnosis, causes, and treatment. DATA SOURCES: A computer-assisted and manual search of the English language literature using MEDLINE 1966-1991, Index Medicus 1988-1992, reference lists of selected articles, and relevant textbooks. STUDY SELECTION: Studies that provide information on lower bowel function and laxative and enema use in the elderly subjects were reviewed. Article selection was not limited by study design. DATA EXTRACTION: Relevant data were abstracted from the results of physiological, cohort and case-control studies, and clinical trials. The text discusses the methodological strengths and flaws of these studies and excludes management approaches formulated from uncontrolled clinical observation. RESULTS OF DATA SYNTHESIS: Constipation of the elderly is not well defined in the current literature. Self-reported constipation and laxative use increase with age, while a similar escalation in true clinical constipation is not shown. Physiological changes in the lower bowel predisposing toward constipation do not occur with normal aging. Patient selection criteria for studies examining the pathophysiology of constipation differ in their definition of constipation and their inclusion of coexisting chronic illness. Nevertheless, there is consistent evidence for prolonged transit through the sigmoid colon and rectum, especially in frail elderly patients, and reduced rectal tone with impaired sensation, particularly in patients with rectal impaction. Few studies rigorously examine "risk factors" and non-pharmacological interventions in constipation. The results of most laxative trials require cautious interpretation because of inclusion of patients without diagnostically proven constipation, use of combined laxative preparations, and unreliable outcome measures. Certain laxative agents however appear more appropriate for use in elderly people. CONCLUSION: Although the subjective complaint of constipation and habitual laxative use increase with age, the epidemiological data suggest that true clinical constipation does not. Physiological changes predisposing toward constipation are not an inevitable consequence of aging, but appear to be specific to the condition. The available data do not confirm many suspected "risk factors" nor the benefits of commonly used non-pharmacological and pharmacological treatments, but they do provide enough information to formulate a practical approach to constipation in elderly persons.

Aged↗
PubMed1993

Effects of recombinant human IGF-I on glucose and leucine kinetics in men.

To examine the effects of recombinant human (rh) insulin-like growth factor I (IGF-I), insulin, and saline on metabolic parameters, we studied 20 young nonobese healthy men. Euglycemic clamps with 240-min IGF-I infusions at two doses (49 and 33 pmol.kg-1 x min-1, n = 8 and 12 subjects) were performed and compared with hyperinsulinemic-euglycemic clamps (2.25 pmol.kg-1 x min-1, n = 9). Leucine and glucose kinetics were examined with L-[1-13C]leucine and [3-3H]glucose. Glucose rate of appearance (Ra) declined equivalently in the 49 pmol.kg-1.min-1 IGF-I and insulin clamps but remained at basal levels during the 33 pmol.kg-1 x min-1 IGF-I infusions. In contrast, Rd of glucose was increased by 176% in the 49 pmol.kg-1 x min-1 IGF-I and 78% in the 33 pmol.kg-1 x min-1 IGF-I infusions. Furthermore, to prevent hypoglycemia after the termination of both rhIGF-I infusions, it was necessary to infuse glucose for an additional 2-20 h. Ra of leucine was suppressed significantly by both IGF-I and insulin, whereas leucine oxidation was not affected by either hormone. Therefore, the rate of disappearance of leucine expressed as the difference between Ra and oxidation rates was significantly reduced in all clamps. In addition, IGF-I significantly suppressed beta-cell secretion without affecting the other glucoregulatory hormones. In contrast to insulin, IGF-I had no apparent effect on lipolysis, as measured by changes in nonesterified fatty acids.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Atrial natriuretic peptide levels in the prediction of congestive heart failure risk in frail elderly.

OBJECTIVE: To develop a noninvasive clinical predictive model for acute congestive heart failure (CHF) in a frail elderly cohort using bedside clinical assessment (medical history and physical examination) and venous atrial natriuretic peptide (ANP) levels. DESIGN: One-year prospective blinded cohort study. SETTING: Life care facility. PARTICIPANTS: Three hundred thirty-one frail, elderly volunteers free of acute illness at study entry (mean +/- SD age, 88 +/- 7 years; 23% male, 77% female). MAIN OUTCOME MEASURE: Clinical episodes of CHF with confirmation of acute pulmonary edema by chest roentgenogram. RESULTS: Fifteen percent of the elderly cohort developed at least one episode of CHF during the 1-year follow-up period. Those developing CHF had significantly higher mean +/- SE ANP values at study entry: 493 +/- 55 vs 207 +/- 15 pmol/L. The risk for development of CHF rose progressively with increasing ANP levels at study entry. In multivariate analysis, only two independent variables significantly predicted CHF: ANP value greater than 200 pmol/L (adjusted odds ratio [OR], 7.9; 95% confidence interval [CI], 3.2 to 19.2) and history of CHF in the previous year (adjusted OR, 7.0; 95% CI, 2.9 to 17). Stratifying the cohort by these two variables results in three CHF risk groups: 55% of the population at 3% annual risk of CHF, 37% of the population at 20% to 24% annual risk of CHF, and 8% of the population at 66% annual risk of CHF. CONCLUSIONS: This simple clinical prediction model identifies elderly subjects at risk for CHF and allows appropriate focusing of medical resources for prevention, early detection, and treatment of this highly morbid clinical syndrome.

Acute Disease↗
PubMed1992

Serum albumin level on admission as a predictor of death, length of stay, and readmission.

We studied the serum albumin level within 48 hours of hospitalization for acute illness to predict in-hospital death, length of stay, and readmission in 15,511 patients older than 40 years. Patients with low serum albumin levels (less than 34 g/L), who made up 21% of the population, were more likely to die, had longer hospital stays, and were readmitted sooner and more frequently than patients with normal albumin levels. The in-hospital mortality was 14% among patients with low albumin levels, as compared with 4% among patients with normal levels. Although the serum albumin level was a nonspecific marker, it was a stronger predictor of death, length of stay, and readmission than age. We conclude that the serum albumin level on admission is an important variable that should be incorporated in severity-of-illness measures based on physiologic indexes.

Adult↗
PubMed1991

Blood pressure, pulse, and neurohumoral responses to nitroprusside-induced hypotension in normotensive aging men.

In order to assess the effects of age on blood pressure, pulse, and neurohumoral responses to hypotensive stress, we infused nitroprusside into healthy young and old men until mean arterial blood pressure was reduced 20% from basal. Elderly subjects were much more sensitive to nitroprusside. Pulse increases in response to this hypotensive stress were markedly reduced in the elderly, but renin, vasopressin, and norepinephrine responses were not different between young and old. We conclude that cardioacceleration, one of the primary defenses against hypotension, is impaired with age. However, neurohumoral responses to hypotension are intact in the elderly.

Adult↗
PubMed1991

Atrial natriuretic peptide suppresses osmostimulated vasopressin release in young and elderly humans.

Atrial natriuretic peptide (ANP) may suppress vasopressin release, but the dynamics of this interaction as well as the influence of age have not been defined. We studied six or seven young (19-40 yr old) and seven elderly volunteers (65-83 yr old) under two circumstances: 1) after infusion of 5% saline (0.04 ml.kg-1.min-1) for 2 h and 2) after the same infusion given with simultaneous synthetic human ANP (0.05 micrograms.kg-1.min-1). Hypertonic saline alone produced a progressive rise in plasma vasopressin with increasing serum sodium. During hypertonic saline alone, vasopressin levels began to rise at an increment in serum sodium of 1.67 +/- 0.35 mM in the young and 1.43 +/- 0.32 mM in the elderly and rose linearly with increasing serum sodium. When ANP was infused with hypertonic saline (with peak ANP levels of approximately 1,000 pM), vasopressin levels began to rise at an increment in serum sodium of 4.43 +/- 0.67 mM in the young and 4.57 +/- 0.43 mM in the elderly (P less than 0.01 vs. saline alone). Furthermore, the vasopressin response for any given serum sodium was significantly reduced in both young and elderly subjects, resulting in a rightward displacement of the curve relating vasopressin response to sodium concentration (P less than 0.001). In conclusion, ANP not only suppresses vasopressin but raises the threshold for release of vasopressin in response to osmotic stimulation in both young and elderly individuals. High circulating ANP levels may be responsible in part for the suppression of vasopressin levels and water diuresis seen during states of volume expansion.

Adult↗
PubMed1991

Islet cell responses to glucose in human transplanted pancreas.

Postsurgery, pancreas transplantation results in alterations of carbohydrate metabolism. Additionally, immunosuppressive therapy impacts on glucose regulation. We evaluated the hormonal and metabolic responses of pancreas allografts, utilizing the hyperglycemic clamp technique coupled with the tritiated glucose methodology, in 11 volunteers who had received simultaneous pancreas-kidney transplantation (P-K) with systemic drainage. Their responses were compared with seven volunteers who had received only a kidney (K) graft and with seven normal control (C) volunteers. Although basal glucose and hepatic glucose output were similar in all three groups, basal insulin, C-peptide, glucagon, and pancreatic polypeptide were highest in the P-K group and lowest in normal subjects. During hyperglycemia, all groups showed a similar characteristic, initial complete suppression of hepatic glucose production, with recovery followed by a later suppression. Peripheral glucose uptake was similar in P-K and C subjects but decreased in K patients. Systemic insulin levels were fourfold higher in the pancreas transplant patients than in healthy subjects. Thus, under basal and hyperglycemic stimulation, 1) hepatic glucose homeostasis is regulated normally, even with pancreatic drainage into the systemic circulation; 2) overall glucose disposal is normal in P-K patients because of marked hyperinsulinemia; and 3) there is loss of tonic inhibition of endocrine pancreatic function secondary to pancreatic denervation.

Adolescent↗
PubMed1990

Principles of surgical risk assessment of the elderly patient.

Treatment of the elderly will comprise increasingly higher proportions of practice time in the future, and issues regarding this treatment are more salient now than ever before. Because more elders are seeking treatment, surgeons need to be comfortable with assessing the potential risks associated with surgical procedures in their elderly patients, many of whom have multiple chronic diseases. Risks that need to be considered are those physiologic changes normal for aging, pathologic changes due to disease, and psychosocial changes that may occur with aging. This article assesses the contribution each of these changes makes to surgical risk, and discusses the principles of gerontology and geriatric medicine that are relevant to risk assessment.

Aged↗
PubMed1990

High-carbohydrate, high-fiber diets increase peripheral insulin sensitivity in healthy young and old adults.

To examine extra-alimentary effects of high-carbohydrate, high-fiber (HCF) diets, insulin-mediated glucose disposal employing the euglycemic clamp and hepatic glucose output (HGO) employing [6,6-2H2]glucose were measured in 12 healthy young and old individuals before and after 21-28 d of an HCF diet. Diet lowered fasting concentrations of glucose from 5.3 +/- 0.2 to 5.1 +/- 0.1 mmol/L (p less than 0.01) and insulin from 66.0 +/- 7.9 to 49.5 +/- 5.7 pmol/L (p less than 0.01). Fasting serum cholesterol decreased from 5.17 +/- 0.18 to 3.80 +/- 0.20 mmol/L (p less than 0.01) in young individuals and from 6.15 +/- 0.52 to 4.99 +/- 0.49 mmol/L (p less than 0.01) in elderly individuals. Fasting serum triglyceride concentrations, basal HGO, and insulin suppression of HGO were unchanged by the diet. Glucose disposal rates increased from 18.87 +/- 1.66 before 23.87 +/- 2.78 mumol.kg-1.min-1 after the diet (p less than 0.02). Therefore, HCF diets may improve carbohydrate economy by enhanced peripheral sensitivity to insulin.

Adult↗