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Biomedical subjects

S Robert

Publications and source records attributed to S Robert.

At least 55 records · Page 3Linked to original sources
PubMed1993

Fatty acid acylation of RNase A using reversed micelles as microreactors.

A water soluble protein, RNAse A, was fatty-acylated using AOT reversed micelles in 2,2,4-trimethyl pentane as microreactors and myristoyl chloride as reagent. Artificial attachment of lipid molecules to this protein was performed for different hydration degrees by changing Wo = [water]/ [AOT], the parameter which controls the microreactor size. The chemically modified protein was monitored using reverse phase HPLC and characterized by HPLC, free amino groups titration, and electrophoresis. An RNase A/myristoyl chloride ratio of 1:4 (mol/mol) at Wo = 7 was found to give 60% of modified protein.

Acylation↗
PubMed1993

Influence of digoxin immune Fab therapy and renal dysfunction on the disposition of total and free digoxin.

OBJECTIVE: To characterize the disposition of total and free serum digoxin following the administration of digoxin Fab antibody in patients with varying degrees of renal function. DESIGN: Observational study of pharmacokinetics and pharmacodynamics. SETTING: Critical care and telemetry units of two university-affiliated teaching institutions, Hartford Hospital and Henry Ford Hospital. PATIENTS: Fourteen digoxin-intoxicated patients (baseline total digoxin > 3.2 nmol/mL) with mean (+/- SD) serum creatinine of 380.1 +/- 212.2 mumol/L who received digoxin Fab antibody therapy. MEASUREMENTS: Serum was drawn every 12 to 24 hours for 80 to 327 hours after Fab administration. Total and free digoxin were assayed in serum by fluorescence polarization immunoassay or modified immunofluorometric assay. RESULTS: Before Fab was administered, total digoxin ranged from 3.5 to 10.5 nmol/mL. After treatment with Fab, total digoxin increased rapidly to a mean (+/- SD) maximum of 51.8 +/- 22.7 nmol/mL and decreased to 7.2 +/- 4.7 nmol/mL at the last measurement. Total digoxin was eliminated in a two-phase fashion. The half-life of the initial phase of total digoxin decline was 11.6 +/- 4.1 hours, and the half-life of the second or terminal elimination phase was 118 +/- 57 hours. Free digoxin levels decreased rapidly following Fab therapy, to a mean nadir of 0.6 +/- 1.1 nmol/mL, but rebounded to a mean maximum free digoxin concentration of 1.7 +/- 1.3 nmol/mL in 77 +/- 46 hours. The time to maximum free digoxin rebound occurred later in patients with end-stage renal disease (n = 4) compared with other patients (127 +/- 40 hours compared with 55 +/- 28 hours). CONCLUSION: Elimination of digoxin following Fab therapy is prolonged in digoxin-toxic patients with renal dysfunction. In addition, rebound of free digoxin is delayed in anephric patients. Monitoring free digoxin following the administration of Fab may be of value in selected patients to guide additional Fab dosing, confirm possible rebound toxicity, or guide the reinitiation of digoxin therapy.

Adult↗
PubMed1993

Acceptability of perindopril in mild-to-moderate chronic congestive heart failure. Results of a long-term open study in 320 patients.

The long-term acceptability of perindopril in mild-to-moderate chronic heart failure (CHF) was evaluated in a multicenter open study. A total of 320 patients with a mean age of 62 +/- 1 years and CHF of New York Heart Association (NYHA) class I (2 patients), II (204 patients), or III (114 patients) were included after a 2-week run-in period during which time vasodilators were stopped and diuretic and/or digoxin therapy stabilized. Perindopril treatment was started at 2 mg, increasing to 4 mg once daily after 2 weeks if supine systolic blood pressure remained > 100 mm Hg. After this dose titration period, follow-up visits were scheduled at monthly intervals for the first 3 months, then at 3-month intervals with a maximum period of follow-up being 30 months. At the time of analysis, mean duration of treatment was 276 days and 208 patients were treated > or = 6 months. Of the 320 patients, 10 (3.1%) died, 9 (2.8%) were withdrawn for worsening heart failure, and 38 (11.9%) for nonfatal adverse events, including cough (2.8%), dizziness or orthostatic discomfort (1.9%), angina pectoris (1.6%), and cutaneous signs (1.3%). Exercise test duration increased from 516 +/- 14 to 659 +/- 19 sec after 6 months of treatment (p < 0.01). At 6 months, 55.6% of patients improved by at least 1 NYHA class. Supine systolic blood pressure decreased slightly from 137 +/- 2 to 132 +/- 1 mm Hg (p < 0.01) and plasma creatinine levels remained stable from 100 +/- 2 to 102 +/- 2 mumol/liter after 6 months of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Determination of gentamicin pharmacokinetics by bioelectrical impedance in critically ill adults.

This investigation compares the accuracy of calculating gentamicin pharmacokinetic parameters by a noninvasive body composition technique (bioelectrical impedance analysis; BIA) with an empiric method, against the two-point method as the criterion standard. A prospective concurrent open label design was used. The 32 medical and surgical intensive care unit beds at Henry Ford Hospital, a not-for-profit, university-affiliated teaching hospital, served as the setting. Twenty critical ill adults, Therapeutic Index Scoring System (TISS) = 4, who required gentamicin as part of their normal course of therapy for gram-negative bacillary infections, were evaluated. Gentamicin Vd and k were calculated by three methods. After measurement of body composition parameters by BIA, previously derived gentamicin dosing equations were used to predict gentamicin volume of distribution (Vd) and elimination rate constant (k) (BIA method). Empiric estimates of these parameters (Vd = 0.3L/kg and k derived from creatinine clearance) were compared with the BIA parameters against a criterion standard Vd and k determined from a two-point sampling of gentamicin serum concentrations. Measurements of BIA parameters and gentamicin serum concentrations were made in duplicate with coefficients of variation, < or = 2% and < or = 3%, respectively. The BIA and empiric methods produced resultant pharmacokinetic parameters (Vd and k) not different than those measured by the two-point method. There were no statistically significant differences in mean error (bias), or mean squared error (precision) for both Vd and k assessed by the empiric or BIA methods.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Transient stray voltage: is it detrimental to growth performance, health status and welfare of market pigs?

The effects of transient stray voltage associated with an alternating current were evaluated in growing-finishing pigs from 9 to 22 weeks of age. Seventy-two pigs were assigned to 9 blocks of 8 animals each. In each block, the following treatments were randomly distributed: a constant voltage differential created between the feeder or drinker and the metallic floor (woven wire), at a level of 0 volt plus 2-volt pulses (0 V-2 V), 2 volts plus 3-volt pulses (2 V-5 V), 5 volts plus 3-volt pulses (5 V-8 V), and a control treatment without any voltage differential (0 V-0 V). The constant voltage was applied 24 h per day. The pulses of 3 s duration were in the form of an increase in the amplitude of the constant 60-Hz signal. One pulse appeared every 20, 40 and 100 s during the hour following feed distribution and every 60, 120 and 300 s during the rest of the day. The animals were fed ad libitum and received fresh feed twice per day. Once during the 2-week periods at 9-10, 13-14, 17-18 and 21-22 weeks of age, the behaviour of the pigs was recorded during the hour following the two daily feed distributions. Animal weights and blood samples were taken every 2 weeks, from 9 to 21 weeks of age. No significant effect of transient stray voltage on any of the variables measured for the feeding, drinking, sitting or lying activities was found (p > 0.05). At 9-10 weeks of age, the number of rooting bouts was higher for the 5 V-8 V treatment (p = 0.03) and the number of events of butting the penmate was higher for the 2 V-5 V treatment (p = 0.05). Although the water and feed intake did not differ between treatments (p > or = 0.39), the average daily gain of the control group was lower than that of treated groups (p = 0.04) at 9 and 10 weeks of age, while the pigs submitted to a 2 V-5 V treatment had a higher daily gain than the pigs in the other treatment groups (p = 0.05) at 17 and 18 weeks of age.(ABSTRACT TRUNCATED AT 400 WORDS)

Age Factors↗
PubMed1993

Forestomach motility and behavior of bull calves according to changes in regimen.

Six 23-week-old bull calves were randomly assigned to a crossover design to study the effects of hay and concentrates given separately (A), silage and concentrates given in complete mixed ration (B), or given separately (C) on reticulo-ruminal motility and eating and resting behaviors after an adaptation period of 14 days (day 14). The effects of a change from one treatment to another on the same variables were also investigated (day 1). The differences observed between day 1 and day 14 indicate that a change in regimen, even not drastic, seems to affect reticulo-ruminal motility, rumination pattern, ruminal inactivity, and resting behavior. As expected, the number of triphasic and biphasic reticular spike bursts, as well as eating and resting behaviors, were affected by the type of forage ingested (A vs. C) on day 14 (p < or = 0.05). Moreover, the mode of distribution of concentrates affected also the variables measured (p < or = 0.05). Although the length of particles in complete mixed ration (B) was the same than in silage and concentrates given separately (C), the effect of regimen B on many variables was similar to that of regimen A or intermediate between A and C. The effect of regimens B and C was similar only for the rumination pattern, even though the number of boluses regurgitated for rumination differed (p < or = 0.05).

Age Factors↗
PubMed1993

Disposition of digoxin immune Fab in patients with kidney failure.

Digoxin and digoxin immune Fab, its antidote, are eliminated renally. However, the disposition of Fab in severe kidney disease is poorly described. Therefore, the disposition of Fab and its relationship to total and free digoxin were studied in five digoxin-toxic patients with end-stage renal disease (n = 4) or severe renal dysfunction (n = 1) with a mean (+/- SD) serum creatinine of 5.9 +/- 1.2 mg/dl (four patients were receiving long-term hemodialysis). Serum was drawn after a clinically neutralizing Fab dose (80 to 160 mg) every 12 to 24 hours for 204 to 327 hours. Fab concentrations were assessed by radioimmunoassay, whereas total digoxin concentrations were assessed with a modified radioimmunoassay or fluorescence polarization immunoassay. The concentration-time profile of Fab appeared to be similar to the concentration-time profile of total digoxin. The mean (+/- SD) half-lives of the alpha and beta disposition phases of Fab were 13 +/- 5 hours and 96 +/- 31 hours, respectively, which were similar to the alpha and beta parameter estimates of total digoxin (14 +/- 4 and 123 +/- 16 hours, respectively). Steady-state volume of distribution and systemic clearance of Fab were 0.29 +/- 0.11 L/kg and 0.057 +/- 0.022 ml/min/kg, respectively. Thus, in comparison to values reported in patients with normal renal function, the elimination of Fab and total digoxin are markedly delayed in patients with end-stage renal disease, which may necessitate prolonged clinical monitoring.

Aged↗
PubMed1993

Bioelectrical impedance assessment of nutritional status in critically ill patients.

The objective of this study was to assess the utility of bioelectrical impedance analysis (BIA) in determining nutritional status in critically ill patients in the intensive care unit (ICU). Data were collected prospectively in 33 mechanically ventilated medical and surgical ICU patients requiring nutrition as part of their care. BIA, with subsequent calculation of body-composition indexes, was performed every other day for the duration of ICU stay. Body cell mass (BCM) changes correlated with energy and protein intakes (r2 = 0.87, P < 0.001 and r2 = 0.67, P < 0.001, respectively). Maintenance of BCM was achieved by a daily provision of 125.5 kJ.kg-1.d-1 (30 kcal.kg-1.d-1) and 1.5 g protein/kg whereas greater intakes allowed restoration of BCM. The mean ratios of exchangeable sodium to potassium (Nae:Ke) improved only in patients achieving positive nitrogen balance (P = 0.013). Body-composition changes determined by BIA represent a feasible adjunctive method for evaluating and monitoring nutritional status in ICU patients.

Adult↗
PubMed1993

Predictability of creatinine clearance estimates in critically ill patients.

OBJECTIVES: a) To evaluate the predictive ability of different creatinine clearance methods as compared with the criterion standard, inulin clearance; and b) to determine which of the predictive methods yields the most accurate estimation of creatinine clearance. DESIGN: Prospective study. SETTING: Medical intensive care unit (ICU) of a university-affiliated tertiary care hospital. INTERVENTIONS: Glomerular filtration rate was measured by the criterion standard, inulin clearance. PATIENTS: Twenty mechanically ventilated adults. MEASUREMENTS: Renal function was assessed by the following procedures: inulin clearance using a standard protocol, 30-min creatinine clearance, 24-hr creatinine clearance, and creatinine clearance estimates by the Cockcroft-Gault equation. Ideal body weight, total body weight or lean body mass with actual serum creatinine or serum creatinine concentration corrected to 1 mg/dL (85 mumol/L) in cachectic patients were sequentially incorporated into the Cockcroft-Gault equation. RESULTS: The Cockcroft-Gault equation, using ideal body weight and the corrected serum creatinine concentration, was the best predictor of inulin clearance with the smallest bias (9.7 +/- 8.6, 95% confidence interval 5.7 to 13.8). The bias encountered with the 30-min creatinine clearance was not different from that value with the 24-hr creatinine clearance (21.6 +/- 33.0, 95% confidence interval 6.2 to 37.1 vs. 25.4 +/- 28.3, 95% confidence interval 11.8 to 42.9). Good correlations existed between inulin clearance and the Cockcroft-Gault equation, using ideal body weight and the corrected serum creatinine concentration (r2 = .81; p = .0001), as well as between inulin clearance and the Cockcroft-Gault equation, using the lower of ideal or total body weight and the higher of the actual serum creatinine concentration or corrected serum creatinine (r2 = .75; p = .0001). The 30-min creatinine clearance and the 24-hr creatinine clearance had poorer agreement with inulin clearance. The incorporation of a corrected serum creatinine value into the Cockcroft-Gault equation consistently led to better predictions and higher correlation coefficients. CONCLUSIONS: The utilization of the Cockcroft-Gault equation as used clinically (the lower of ideal or total body weight and the higher of actual serum creatinine or corrected serum creatinine concentration to 1 mg/dL [85 mumol/L]) results in more accurate predictions of glomerular filtration rate in the medical, critically ill patient than urine creatinine clearance measures. If creatinine clearance measures are used, the 30-min collection provided results not different from those results obtained with 24-hr urinary collections.

Adult↗
PubMed1992

Transcranial Doppler to evaluate the effects of antihypertensive medication on cerebral blood flow velocity.

The effect of oral nifedipine on cerebral blood flow velocity was studied in six elderly hypertensive patients using transcranial Doppler. Serial measurements of blood pressure (BP), middle cerebral artery (MCA) flow velocity and nifedipine serum concentrations were obtained over an 8-hour period. The authors found a significant inverse relationship between MCA velocities and nifedipine concentrations, independent of BP changes. These results are consistent with a direct vasodilatory effect of nifedipine on cerebral vessels and support the use of TCD in pharmacodynamic investigations of the cerebral vasculature.

Aged↗
PubMed1992

Determination of free serum digoxin concentrations in digoxin toxic patients after administration of digoxin fab antibodies.

Digoxin fab antibody therapy is known to interfere with digoxin immunoassays causing spurious serum digoxin concentrations. The reliability and precision of three digoxin immunoassays--Baxter Dade Stratus (BDS), Syva affinity column enzyme-mediated immunoassay (EMIT), and the reference assay Abbott TDx fluorescence polarization immunoassay following ultrafiltration (FPIA-UF)--were compared in eight digoxin toxic patients treated with digoxin fab antibodies. Five to eight blood samples were drawn serially up to 204 h post digoxin fab therapy. The serum digoxin concentration in each sample was determined by each of the three assays. The mean (+/- SD) area under the serum digoxin concentration-time curve was significantly lower for FPIA-UF than for BDS or EMIT (86.1 +/- 58.2 vs 158.1 +/- 88.6 and 176.3 +/- 115.3 h.ng/ml p less than 0.01, respectively). BDS correlated better with FPIA-UF (r2 = 0.71) than did EMIT (r2 = 0.45). Predictive performance of the BDS and EMIT assays demonstrated that the mean prediction error (bias) (0.62 vs 0.78 ng/ml) and the mean squared prediction error (precision) (0.48 vs 0.76) differed significantly from zero (p less than 0.05). However, BDS had significantly less bias and greater precision than did EMIT (p less than 0.05). In the presence of digoxin fab antibodies, BDS is a better predictor of free serum digoxin concentration than is EMIT, but both have considerable bias. Based on these results, FPIA-UF should be the assay of choice for determining free serum digoxin concentrations during fab therapy.

Adult↗
PubMed1992

"Brain attack": an indication for thrombolysis?

OBJECTIVE: The primary objective of this article is to introduce the reader to the use of thrombolytics in the acute treatment of ischemic stroke. Theory and experimental evidence to support this approach are emphasized in addition to potential adverse effects of thrombolysis. DATA SOURCES: A MEDLINE search was used to identify pertinent literature, including reviews. STUDY SELECTION: Studies were selected for detailed review if they involved stroke patients and addressed possible toxicities of therapy. Any abstracts concerning ongoing clinical trials also were reviewed. DATA EXTRACTION: Data from animal investigations using tissue plasminogen activator for the acute treatment of several models of cerebral ischemia were used to support the importance of early treatment (within six hours of symptom onset). Also, studies performed in animal models of stroke revealed that thrombolysis could be accomplished safely in acute ischemic stroke. All human studies published to data are anecdotal case reports, but point to the safety of thrombolysis if administered early. Reviews of ongoing multicenter trials are taken from published abstracts and proceedings. DATA SYNTHESIS: Thrombolysis holds promise as a hyperacute therapy for acute stroke; however, the risk of intracerebral hemorrhage remains. Crucial to the success of this and any other therapy for acute stroke is the ability to treat patients within hours of symptom onset. Also, the importance of concomitant medications such as heparin and aspirin has not yet been addressed. CONCLUSIONS: Pharmacists need to be knowledgeable of new treatments of stroke and the risks associated with them. As patient educators, pharmacists can contribute to public awareness by promoting the early recognition of stroke symptoms. As pharmacotherapists, pharmacists need to understand the risks and the important monitoring parameters related to thrombolysis. The results of ongoing multicenter clinical trials are awaited before making a final judgment on the usefulness of thrombolysis in acute ischemic stroke.

Anistreplase↗
PubMed1992

Prediction of glomerular filtration rate using aminoglycoside clearance in critically ill medical patients.

OBJECTIVE: The aim of this preliminary investigation was to evaluate the use of aminoglycoside serum concentrations as a surrogate measure of the glomerular filtration rate (GFR) in comparison with other measured and empiric methods against inulin, the criterion standard measure of GFR. DESIGN: A consecutive sample of all eligible patients. SETTING: An eight-bed medical intensive care unit in a university-affiliated tertiary-care teaching hospital. PATIENTS: Ten critically ill medical patients receiving gentamicin or tobramycin for presumed or documented gram-negative bacillary infection were enrolled in the study. The patients were mechanically ventilated and had underlying organ system dysfunction. All ten patients completed the study. INTERVENTION: Patients underwent renal functional assessment by measured inulin (Cl(in)) and 24-hour urinary creatinine clearance (Clcr). Aminoglycoside serum concentrations were used to estimate GFR and were compared with the two measured methods and a creatinine clearance calculated with the Cockcroft-Gault method (ClCG). All evaluations were performed the same day. RESULTS: Cl(in) averaged 51.6 +/- 35.0 mL/min and serum creatinine ranged from 0.3 to 5.4 mg/dL (26.5 to 477.3 mumol/L). Steady-state peak and trough aminoglycoside concentrations were 6.1 +/- 1.4 and 1.3 +/- 0.9 micrograms/mL, respectively. There were no statistically significant differences between the various methods, although the aminoglycoside-calculated GFR (Cl(amg)) 95 percent confidence intervals were smaller than Clcr and ClCG compared with Cl(in). Mean absolute errors were smaller with Cl(amg) than with Clcr and ClCG. Regression results indicated that only Cl(amg) and ClCG demonstrated agreement with Cl(in) (lines not different from y = x). However, the Cl(amg) showed closer agreement, with a mean square error almost half that of ClCG (9.6 vs. 18.1). CONCLUSIONS: Cl(amg) can be used routinely as an estimate of GFR in critically ill patients, with less error than empiric methods.

Adult↗
PubMed1992

Cerebral blood flow changes with enalapril.

Patients with carotid artery occlusive disease (CAOD) may be at increased risk of iatrogenic cerebral hypoperfusion. Using the 133xenon-inhalation technique, we evaluated the effects of enalapril on regional cerebral blood flow (CBF) in 14 patients with chronic hypertension, 7 with CAOD and 7 without CAOD (no CAOD). Regional CBF and blood pressure were measured before and 60 minutes after a single dose of enalapril. Changes in mean arterial pressure after enalapril were not significantly different between the two groups: CAOD -4.67 +/- 8.7 mm Hg, no CAOD -6.18 +/- 8.2 mm Hg. Changes in mean CBF after enalapril were also not statistically different: CAOD -1.0 +/- 3.9, no CAOD 1.0 +/- 2.8. In the CAOD group only, however, changes in CBF were significantly related to increasing age (r = -0.9253, p less than 0.01), such that in patients 65 years or older CBF tended to decrease, whereas in younger patients it increased. Elderly patients with CAOD may be at increased risk of iatrogenic cerebral hypoperfusion, and it may be appropriate to evaluate prospectively the effects of antihypertensive medications on CBF.

Age Factors↗
PubMed1992

[Specific induction by phorbol ester of the gene transcription and of the activity of ornithine decarboxylase in two control and transformed epithelial cell lines. Modulator effect of anti-inflammatory agents].

The mechanism of ornithine decarboxylase (ODC) induction by phorbol ester (TPA) has been studied in two permanent epithelial cell lines, a control (Ctr) and a Benzo (a) pyrene transformed line (BaP-tr); the degree of ODC gene expression (ODC-mRNA) was evaluated in comparison to the ODC activity. A small dose of TPA (4 x 10(-8) M) highly induced ODC activity in these cells. The induction levels differed however, corresponding respectively to 4:1 (induced: basal ODC) in Ctr cells and to 2:1 in BaP-tr cells. This difference reflected the variation of ODC gene expression; the ODC-mRNA induction was 6:1 in Ctr cells and 3:1 in BaP-tr cells. Repetitive TPA treatment decreased the ODC induction in these cells, as compared to that resulting from a single TPA treatment. Studies of ODC modulation were performed in presence of anti-inflammatory agents. In the two cell lines, Indomethacin (anti-cyclooxygenase) did not change the level of ODC induction by TPA. Nordihydroguaiaretic acid (NDGA, anti-lipoxygenase) inhibited this induced ODC. These results differed from that obtained in vivo in mouse skin. Dexamethasone (DXME, anti-phospholipase A2) showed different action according to treatment time. Used together with TPA (t0), DXME inhibited ODC induction by the carcinogen; with three hours delay after TPA (t3), DXME treatment stimulated ODC in the cells. This divergent action may be reproduced by Actinomycin D, while Cycloheximide only exhibited constant inhibition. Studies now in progress suggested that the inhibition of TPA induced ODC by DXME may reflect ODC gene repression, as for the stimulating effect it could be related to ODC post-transcriptional modulation, owing to the decrease of proteolytic action.

Animals↗
PubMed1991

The electrical and spectroscopic properties of planar asymmetrical membranes incorporating chlorophyll a and plastoquinone-9. Model of incorporation of chlorophyll a and plastoquinone-9.

We have studied the incorporation of chlorophyll a and plastoquinone-9 in Montal-Mueller membranes. In particular, we have been interested by the influence of both the lipid : chlorophyll a ratio and the asymmetry of incorporation of the constituents on the electrical and fluorescence spectroscopic properties of the planar membranes built up from these constituents. The phospholipid matrix was made from phosphatidylethanolamine and phosphatidylserine. The monitoring of the fluorescence spectral properties of chlorophyll a incorporated in various concentrations leads to the conclusion that chlorophyll a is incorporated in the bilayers in monomeric form inside microdomains. It is shown that chlorophyll a is positioned in these microdomains in such a way that the porphyric ring is interacting with the polar head of the lipid molecules where the interface polarity shows a dielectric constant varying between 25 and 35. The phytyl chain is embedded in the bilayer core, serving as an anchor, running parallel to the aliphatic chains of the phospholipids. We have also monitored the position of the plastoquinone-9 molecules within the bilayer. We found that plastoquinone-9 is incorporated in the center plane of the bilayer, increasing the thickness of the bilayer. This result confirms evidence, gathered in the literature from monolayer and differential scanning calorimetry studies, that long chain quinones and especially plastoquinone-9 are embedded deeply within the hydrophobic core of the bilayer. We also show that when chlorophyll a and plastoquinone-9 are present together in the bilayer, the quinolic ring of the plastoquinone-9 molecule positions itself in the free volume created by the bulky porphyric ring of a chlorophyll a molecule.

Chemical Phenomena↗
PubMed1991

Is there a reliable index of glomerular filtration rate in critically ill patients?

Assessment of renal function in critically ill patients is important for appropriate individualization of dosage regimens and nutrition, but is complicated by a high incidence of acute renal failure (ARF). The most common cause of ARF in intensive care unit (ICU) patients is hypoperfusion. Other causes of ARF include intrinsic injury, nephrotoxicity, and postrenal obstruction. ARF is associated with a decreased glomerular filtration rate (GFR), reduced or maintained urine output (nonoliguric renal failure), and alterations in other commonly obtained urinary indices. Twenty-four-hour or shorter urinary creatinine clearance studies may overpredict GFR as creatinine is both filtered and secreted. The use of serum creatinine in empiric predictive equations is impaired in ICU patients because of decreases in creatinine production due to immobilization and malnutrition or increases in creatinine production due to catabolic illnesses. Adjustment of empiric methods by employing lean body weight, ideal body weight, or corrected serum creatinine values has not been evaluated against uncorrected values in this population, but is routinely performed in clinical practice. Inulin and radiolabeled substances are not practical for routine clinical use and may overpredict GFR in ARF due to backleak of large molecular-weight substances through the tubules. Comparative clinical trials have shown essentially equivalent performance of empiric methods relative to 24-hour urinary creatinine clearance in adults. No studies have compared these methods to a reference method for determination of GFR. Until conclusive data become available, clinicians should cautiously compare results from at least two independent methods of assessment to estimate renal functional impairment in ICU patients.

Acute Kidney Injury↗