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Biomedical subjects

J H Reeves

Publications and source records attributed to J H Reeves.

17 recordsLinked to original sources
PubMed2004

Nasopharyngeal oxygen in adult intensive care--lower flows and increased comfort.

Nasopharyngeal oxygen therapy, the delivery of supplementary oxygen into the nasopharynx via a fine catheter placed through the nose, is a simple technique used in postoperative anaesthetic care units and paediatric intensive care, but never described in the setting of adult intensive care. In a prospective crossover design, we compared nasopharyngeal oxygen therapy with semi-rigid plastic mask (Hudson Mask) in 50 unintubated adult patients receiving supplemental oxygen. We measured oxygen flow rate to achieve cutaneous saturations 93 to 96%, and patient comfort by visual analogue score. Nasopharyngeal oxygen therapy consumed significantly less oxygen than mask administration (3.0+/-0.9 vs 6.7+/-2.1 l/min, P<0.001) and was associated with significantly higher comfort than the mask (7.5+/-1.6 cm vs 5.2+/-1.8, P<0.001).

Adult↗
PubMed2000

A prospective, multicenter study of the epidemiology, management, and outcome of severe acute renal failure in a "closed" ICU system.

The safety and effectiveness of "closed" intensive care units (ICUs) are highly controversial. The epidemiology and outcome of acute renal failure (ARF) requiring replacement therapy (severe ARF) within a "closed" ICU system are unknown. Accordingly, we performed a prospective 3-mo multicenter observational study of all Nephrology Units and ICUs in the State of Victoria (all "closed" ICUs), Australia, and focused on the epidemiology, treatment, and outcome of patients with severe ARF. We collected demographic, clinical, and outcome data using standardized case report forms. Nineteen ward patients and 116 adult ICU patients had severe ARF (13.4 cases/100, 000 adults/yr). Among the ICU patients with severe ARF, 37 had impaired baseline renal function, 91 needed ventilation, and 95 needed vasoactive drugs. Intensivists controlled patient care in all cases. Continuous renal replacement therapy (CRRT) was used in 111 of the ICU patients. Nephrological opinion was sought in only 30 cases. Predicted mortality was 59.6%. Actual mortality was 49.2%. Only 11 ICU survivors were dialysis dependent at hospital discharge. In the state of Victoria, Australia, intensivists manage severe ARF within a "closed" ICU system. Renal replacement is typically continuous and outcomes compare favorably with those predicted by illness severity scores. Our findings support the safety and efficacy of a "closed" ICU model of care.

Acute Kidney Injury↗
PubMed1999

The impact of race and fractures on mortality in a postmenopausal Medicaid population.

The purpose of this study was to model fractures and survival by age and race in a large postmenopausal Medicaid population. All Georgia Medicaid claims were abstracted for the years 1992, 1993, and 1994. Claims for postmenopausal women (> or =50 years of age) were retained, and patients with fractures were identified by International Classification of Diseases, Ninth Revision codes for fracture. A survival analysis was conducted using Kaplan-Meier estimators to evaluate the effect of fracture, age, and race on 3-year survival. A total of 159,400 white and black postmenopausal women were identified. The cohort with fracture totaled 5933 patients, with femoral fractures constituting 46% of all fractures. Discounting those with fracture before the study, the fracture incidence was approximately 1.2% in this postmenopausal female cohort. The survival analysis suggested that after age was accounted for, black postmenopausal women had a 42% increased risk of death within 3 years of fracture, compared with 13% for white women. However, postmenopausal black women were approximately 50% less likely to experience a fracture, and postmenopausal black women without fracture had better survival rates than comparable white women. Mortality crossover and the diminished likelihood of fracture mask the true nature of fracture survival in postmenopausal black women. Postmenopausal black women with fracture are at greater risk of dying than their white counterparts.

Aged↗
PubMed1999

Continuous plasmafiltration in sepsis syndrome. Plasmafiltration in Sepsis Study Group.

OBJECTIVE: To assess the effect of plasmafiltration (PF) on biochemical markers of inflammation, cytokines, organ dysfunction, and 14-day mortality in human sepsis. DESIGN: Multicenter, prospective, randomized, controlled clinical trial. SETTING: Seven university-affiliated intensive care units. PATIENTS: Thirty patients (22 adults, eight children) with new (<24 hrs) clinical evidence of infection and sepsis syndrome were enrolled. Fourteen of 30 (nine adults, five children) were randomized to PF. INTERVENTIONS: All patients received protocol-driven supportive intensive care, and those randomized to PF received continuous plasma exchange for 34 hrs using a hollow-fiber plasma filter. MEASUREMENTS AND MAIN RESULTS: Illness severity and risk of death were calculated with the Pediatric Risk of Mortality (children) and the Acute Physiology and Chronic Health Evaluation II (adults) scales. Plasma samples (0, 6, 24, and 48 hrs) were assayed for acute-phase proteins (albumin, globulin, C-reactive protein, alpha1-antitrypsin, haptoglobin), inflammatory mediators (complement fragment C3, thromboxane B2), and cytokines (interleukin-6, granulocyte colony-stimulating factor, leukemia inhibitory factor). Sieving coefficients were estimated from filtrate concentrations at 3 hrs. The two groups were matched for incidence of septic shock (13 of 14 vs. 11 of 16), refractory shock (three of 14 vs. six of 16), bacteremia (six of 14 vs. five of 16), severity of illness, and calculated risk of death (0.68 vs. 0.64). There was no difference in mortality. Eight of 14 PF patients (57%) and eight of 16 controls (50%) survived for 14 days (p = .73, Fisher's exact test). Multiple logistic regression revealed age (odds ratio, 16.4:1; 95% confidence interval, 2.12-infinity) and shock (10.6:1; 1.32-infinity) as significant predictors of death; plasmafiltration was associated with a nonsignificant reduction in the risk of death (odds ratio, 1.78:1; 95% confidence interval, 0.20-18.1). The mean (SD) number of organs failing in the first 7 days in the PF group was 2.57 (0.94) vs. 2.94 (0.85) in controls (p = .37, Mann-Whitney U test). Both groups had similarly elevated plasma concentrations of all inflammatory mediators except complement fragment C3 at study entry. Leukemia inhibitory factor was detectable in four patients only. PF did not influence mean concentrations of interleukin-6, granulocyte colony-stimulating factor, thromboxane B2, total white cell count, neutrophil count, or platelet count, but it was associated with significant reductions of alpha1-antitrypsin, haptoglobin, C-reactive protein, and complement fragment C3 in the first 6 hrs (p < .05). The sieving coefficients for all inflammatory mediators approached unity. CONCLUSIONS: PF caused a significant attenuation of the acute-phase response in sepsis. There was no significant difference in mortality, but there was a trend toward fewer organs failing in the PF group that suggests that this procedure might be beneficial.

Acute-Phase Proteins↗
PubMed1999

A controlled trial of low-molecular-weight heparin (dalteparin) versus unfractionated heparin as anticoagulant during continuous venovenous hemodialysis with filtration.

OBJECTIVE: To compare the efficacy, safety, and cost of fixed-dose low-molecular-weight heparin (dalteparin) with adjusted-dose unfractionated heparin as anticoagulant for continuous hemofiltration. DESIGN: Prospective, randomized, controlled clinical trial. SETTING: University-affiliated adult intensive care unit PATIENTS: All patients requiring continuous hemofiltration for acute renal failure or systemic inflammatory response syndrome (SIRS) were eligible. Fifty-seven patients were enrolled. Eleven were excluded, seven because of major protocol violations and four died before hemofiltration. INTERVENTIONS: Patients received continuous venovenous hemodialysis with filtration with prefilter replacement at 500 mL/hr and countercurrent dialysate at 1000 mL/hr. Filters were primed with normal saline containing anticoagulant. Dalteparin-treated patients received a commencement bolus of 20 units/kg and a maintenance infusion at 10 units/kg/hr. Heparin-treated patients received a commencement bolus of 2000-5000 units and a maintenance infusion at 10 units/kg/hr, titrated to achieve an activated partial thromboplastin time in the patient of 70-80 secs. MEASUREMENTS AND MAIN RESULTS: The primary outcome measure--time to failure of the hemofilter--was compared using survival analysis. Twenty-two patients (13 with acute renal failure and nine with SIRS; total, 41 filters) were randomized to heparin. Twenty-five patients (16 with acute renal failure and nine with SIRS; total, 41 filters) were randomized to dalteparin. Mean (SE) activated partial thromboplastin time in the heparin group was 79 (4.3) secs. Mean (SE) anti-factor-Xa activity in the six patients given dalteparin who were assayed was 0.49 (0.07). Mean (SE) prehemofiltration platelet count was 225 (35.5) x 10(9) for heparin and 178 (18.1) x 10(9) for dalteparin (p = .24, unpaired Student's t-test). Mean (SE) prehemofiltration hemoglobin was 11.4 (0.61) g/dL for heparin and 10.6 (0.38) g/dL for dalteparin (p = .31, unpaired Student's t-test). PRIMARY OUTCOME: There was no significant difference in the time to failure between the two groups (p = .75, log rank test). For dalteparin, Kaplan-Meier (K-M) mean (SE) time to failure of the hemofilter was 46.8 (5.03) hrs. For heparin, K-M mean (SE) time to failure was 51.7 (7.51) hrs. The 95% CI for difference in mean time to failure was -13 to 23 hrs. The power of this study to detect a 50% change in filter life was >90%. SECONDARY OUTCOMES: Mean (SE) reduction in platelet count during hemofiltration was 63 (25.8) x 10(9) for heparin and 41.8 (26.6) x 10(9) for dalteparin (p = .57, unpaired Student's t-test). Eight patients given dalteparin and four patients given heparin had screening for heparin-induced thrombocytopenia; three of the dalteparin patients and one of the heparin patients were positive (p = 1.0, Fisher's exact test). There were three episodes of trivial bleeding and two episodes of significant bleeding for dalteparin, and there were three episodes of trivial bleeding and four episodes of significant bleeding for heparin (p = .53, chi-square test). The mean (SE) decrease in hemoglobin concentration during hemofiltration was 0.51 (0.54) g/dL for heparin and 0.28 (0.49) g/dL for dalteparin (p = .75, unpaired Student's t-test). The mean (SE) packed-cell transfusion volume during hemofiltration was 309 (128) mL for heparin and 290 (87) mL for dalteparin (p = .90, unpaired Student's t-test). Daily costs, including coagulation assays, of hemofiltration were approximately 10% higher using dalteparin than with heparin. CONCLUSIONS: Fixed-dose dalteparin provided identical filter life, comparable safety, but increased total daily cost compared with adjusted-dose heparin. Unfractionated heparin remains our anticoagulant of choice for continuous hemofiltration in intensive care.

Acute Kidney Injury↗
PubMed1996

Haemodynamic effects of arteriovenous and venovenous haemofiltration in piglets.

The aim of this study was to compare the early haemodynamic effects of continuous arteriovenous haemofiltration (CAVH) with those of continuous venovenous haemofiltration (CVVH) in normal and endotoxic piglets, within the framework of a two-period cross-over trial. Sixteen domestic piglets (weight 6-18 kg) underwent 1 h of CAVH followed by 1 h of CVVH or 1 h of CVVH followed by 1 h of CAVH. Six were pre-treated with a graded endotoxin infusion to simulate clinical sepsis. The main measurements included: heart rate; mean arterial (MAP), pulmonary artery, central venous and pulmonary artery occlusion pressures; thermodilution cardiac output; and calculated systemic (SVRI) and pulmonary vascular resistance indexes. Each measurement was performed immediately before and 30 min after commencement of each technique of filtration. Commencement of haemofiltration in normal piglets caused minimal haemodynamic effects. In endotoxic piglets, commencement of filtration, whether CAVH or CVVH, caused a haemodynamic change which was significantly more pronounced in the first filter (SVRI -39%, MAP -32%) than the second filter (SVRI +22%, MAP +0.9%) (SVRI, P=0.01, first filter vs. second) (MAP, P=0.009 first filter vs. second). In conclusion, there were no significant differences between the early haemodynamic effects of CAVH and CVVH in normal or endotoxic piglets. The haemodynamic effects of either technique may become more significant in the presence of sepsis.

Animals↗
PubMed1996

Induced radioactivity of LDEF materials and structural components.

We present an overview of the Long Duration Exposure Facility (LDEF) induced activation measurements. The LDEF, which was gravity-gradient stabilized, was exposed to the low Earth orbit (LEO) radiation environment over a 5.8 year period. Retrieved activation samples and structural components from the spacecraft were analyzed with low and ultra-low background HPGe gamma spectrometry at several national facilities. This allowed a very sensitive measurement of long-lived radionuclides produced by proton- and neutron-induced reactions in the time-dependent, non-isotropic LEO environment. A summary of major findings from this study is given that consists of directionally dependent activation, depth profiles, thermal neutron activation, and surface beryllium-7 deposition from the upper atmosphere. We also describe a database of these measurements that has been prepared for use in testing radiation environmental models and spacecraft design.

Aluminum↗
PubMed1995

Blood filtration in children with severe sepsis: safe adjunctive therapy.

OBJECTIVE: To review the safety and efficacy of haemofiltration and plasmafiltration in children with severe sepsis. DESIGN: Retrospective case notes analysis. SETTING: University Paediatric Intensive Care Unit. PATIENTS: All children admitted to the intensive care unit between November 1985 and May 1992 with a primary diagnosis of severe sepsis who also received blood filtration therapy. INTERVENTIONS: Continuous haemofiltration (HF) 18 patients; continuous haemofiltration and plasmafiltration (PF) 9 patients. MEASUREMENTS AND RESULTS: 27 children with sepsis-induced MOSF, median age 26.6 months (range 0.33-185), median weight 12 kg (range 2.5-58), mean PRISM score 19.4 (SD 8.6), mean number of organs failing 2.78 (SD 0.9) received filtration for a median duration of 36 hours (range 2-145). Eight (30%) survived (HF 5/18, PF 3/9). There was no significant difference in the demographic features between the HF group and the PF group and no difference in mortality. The two groups were pooled to assess the effect of commencement of filtration on clinical wellbeing. Arterial blood gases, electrolytes, full blood examination, ventilator settings and doses of inotropes were recorded immediately prior to commencement of filtration and 18 h after commencement. Serum anion gap and osmolality were calculated using conventional formulae. There were no significant changes in the level of cardiorespiratory support, or biochemical markers of severity following commencement of filtration. Platelet count fell 32% (p = 0.029) but no bleeding was encountered. No severe complications were observed during 1222 h of filtration. No bleeding or infection was observed at the site of cannulation. One child developed haemodynamic instability following commencement of plasmafiltration necessitating abandonment of the procedure. CONCLUSION: Haemofiltration or plasmafiltration can be performed safely in children with severe sepsis but their effect on outcome remains unknown.

Adolescent↗
PubMed1994

A review of venovenous haemofiltration in seriously ill infants.

Between April 1989 and October 1991, 13 severely ill infants, median age 13 days (range 1-180 days), median weight 3.5 kg (range 2.5-4.8 kg), received continuous venovenous haemofiltration (CVVH) for a median duration of 39 h (range 5-234 h). Filtration was performed through a double lumen catheter inserted into a central vein. The indications for filtration included acute renal failure (8), fluid overload (5), inborn errors of metabolism (3) and sepsis (1). Some infants had more than one indication. The median Paediatric Risk of Mortality (PRISM) score on the day of admission to the intensive care unit was 27 (range 8-42). No change in the level of respiratory support was required following the commencement of CVVH. Serum electrolyte concentrations and plasma osmolality remained normal throughout. Serum creatinine fell from a mean of 0.11 mmol/L (95% CI 0.058-0.168) to 0.07 mmol/L (CI 0.034-0.112). Urea fell from a mean of 9.5 mmol/L (CI 4.4-14.6) to 6.5 mmol/L (CI 2.7-10.3). Platelet counts fell by 40-50% from a mean of 126 x 10(6)/mm3 (CI 72-180) to 69 x 10(6)/mm3 (CI 36-103) 18 h following commencement of filtration but no bleeding was encountered. The main complication was a thrombosis of the superior and inferior vena cava in one infant. Four infants survived to be discharged from intensive care. Continuous venovenous haemofiltration, with its inherent advantages over arteriovenous haemofiltration, is feasible in small infants using standard paediatric equipment.

Acute Kidney Injury↗
PubMed1992

Heterogeneity in the substitution process of amino acid sites of proteins coded for by mitochondrial DNA.

Several forms of maximum likelihood models are applied to aligned amino acid sequence data coded for in the mitochondrial DNA of six species (chicken, frog, human, bovine, mouse, and rat). These models range in form from relatively simple models of the type currently used for inferring phylogenetic tree structure to models more complex than those that have been used previously. No major discrepancies between the optimal trees inferred by any of these methods are found, but there are huge differences in adequacy of fit. A very significant finding is that the fit of any of these models is vastly improved by allowing a certain proportion of the amino acid sites to be invariant. An even more important, although disquieting, finding is that none of these models fits well, as judged by standard statistical criteria. The primary reason for this is that amino acid sites undergo substitution according to a process that is very heterogeneous. Because most phylogenetic inference is accomplished by choosing the optimal tree under the assumption that a homogeneous process is acting on the sites, the potential invalidity of some such conclusions is raised by this article's results. The seriousness of this problem depends upon the robustness of the phylogenetic inferential procedure to departures from the underlying model.

Amino Acid Sequence↗
PubMed1990

Accurate monitoring of neuromuscular blockade using a peripheral nerve stimulator--a review.

For normal anaesthetic practice, monitoring of neuromuscular blockade is best performed by stimulation of the ulnar nerve at the wrist with a peripheral nerve stimulator and evaluation of the response of the thumb. Determination of the initial threshold for stimulation in the awake patient to allow estimation of the current required for supramaximal stimulation is an important set-up procedure to improve accuracy. The degree of paralysis of specific muscle groups such as the diaphragm can be inferred from their sensitivity to neuromuscular blocking agents relative to adductor pollicis. Monitoring with different stimulation patterns allows a wide spectrum of muscle paralyses to be evaluated.

Electric Stimulation↗
PubMed1989

Comparison of ceftriaxone with cefotaxime in serious chest infections.

Ceftriaxone is a new, third-generation cephalosporin that, because of its long half-life, offers potential advantages of cost and convenience over similar agents such as cefotaxime. We compared the two drugs in a prospective, randomized study of the treatment of chest infections in seriously ill patients. Fifty-one patients (90 percent of whom were mechanically ventilated) received either ceftriaxone, 2g IV once daily, or cefotaxime, 2 g IV thrice daily, for five days. The two groups of patients appeared demographically comparable. Ceftriaxone in a single daily dose of 2 g once daily may not be satisfactory for the treatment of serious chest infections.

Adult↗
PubMed1988

An evaluation of eight peripheral nerve stimulators for monitoring neuromuscular blockade.

The features of eight commercially available peripheral nerve stimulators were compared with those evolved as ideal for monitoring neuromuscular blockade. The pulse waveforms were satisfactory except for that delivered by the CIG series 80 nerve/muscle stimulator. The error in timing of the stimulation patterns was up to 60% in the Professional Instruments NS-2C compared with 8% or less in the other devices. All of the stimulators had maximum current outputs suitable for monitoring with surface stimulating electrodes. The current delivered by the CIG series 80 nerve/muscle stimulator and the Stimlocator SL1.4 sagged by 21% and 25% respectively during a tetanus. The Digistim III, Bard Biomedical 750 digital and the Professional Instruments NS-2C had accurate digital readouts of delivered current.

Electric Stimulation↗
PubMedDate not supplied

A comparison of solute clearance during continuous hemofiltration, hemodiafiltration, and hemodialysis using a polysulfone hemofilter.

The clearance of urea, creatinine, amino acids, vancomycin, and phenytoin was measured in vivo in a small animal model during continuous venovenous (CVV) hemofiltration, CVV hemodiafiltration, and CVV hemodialysis using a 0.25 m2 polysulfone hemofilter. Six domestic piglets (weighing 6-11.8 kg) each received 1 hr of all three techniques in random order. Blood flow was 50 ml/min. During CVV hemofiltration, filtrate production was 500 ml/hr and dialysate flow was zero. During CVV hemodiafiltration, filtrate production was 250 ml/hr and dialysate flow was 250 ml/hr. During CVV hemodialysis, net filtrate production was zero and dialysate flow was 500 ml/hr. The ratio of concentration of solute in filter effluent to concentration in whole plasma was derived for each solute during each of the three techniques. Mean (SD) effluent:plasma ratio for urea during CVV hemofiltration was 0.957 (0.038), CVV hemodiafiltration 0.876 (0.109), and CVV hemodialysis 0.754 (0.123); creatinine 0.942 (0.05), 0.934 (0.056), and 0.814 (0.057); amino acids 0.996 (0.344), 0.904 (0.196), and 0.778 (0.18). For small unbound solutes, there is a decrease in clearance of 6% from CVV hemofiltration to CVV hemodiafiltration and a further decrease of 14% from hemodiafiltration to hemodialysis. The effluent:plasma ratio for vancomycin during CVV hemofiltration was 0.739 (0.082), CVV hemodiafiltration 0.643(0.063), and CVV hemodialysis 0.509 (0.081), corresponding to a decrease of 30% from CVV hemofiltration to CVV hemodialysis. The effluent:plasma ratio for phenytoin was 0.302 (0.028) during CVV hemofiltration and was not significantly different during CVV hemodiafiltration or CVV hemodialysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMedDate not supplied

Albumin priming does not prolong hemofilter life.

The hypothesis was tested that prepriming a hemofilter and lines with heparinized human albumin (NSA) instead of heparinized saline (NS) increases filter survival time. In a university affiliated intensive care unit, all patients were eligible who required continuous venovenous hemodiafiltration and who did not have pre-existing coagulopathy or contraindications to heparin. New hemofilters were randomized to priming with 2 liters NS or 1 liter NS followed by 500ml NSA. The prime was recirculated for at least 30 minutes before connection to the patient. Anticoagulation was tightly controlled, aiming for a patient activated partial thromboplastin time (APTT) of 60 seconds. Survival analysis was used to compare filter life. Elective discontinuation (e.g., for surgery) were treated as censored data. A total of 91 hemofilters were used in 40 patients during 9 months: 45 randomized to NS, and 46 to NSA. Of these, 57 hemofilters were used until spontaneous failure, 28 NS and 29 NSA; 34 hemofilters were electively discontinued, 17 in each group. Anticoagulation was identical in both groups; the mean APTT value (+/- SE) was 58.2 seconds (+/- 3.1) for NS and 58.0 seconds (+/- 2.8) for NSA (p > 0.9 unpaired t-test). Platelet counts were very similar at 170 x 10(9) (+/- 21.8) for NS and 181 x 10(9) (+/- 23.7) for NSA (p = 0.74 unpaired t-test). There was no significant difference in the filter life between the two groups. For NS, median filter life was 37.8 hours (range 0.6-120); for NSA, median filter life was 45.4 hours (range 2.5-109; p = 0.998 log rank). The power to detect a 50% improvement in filter life was > 90%. Based on this data, the use of albumin priming as an aid to increased hemofilter life can not be recommended.

Acute Kidney Injury↗