The effects of intravenous anesthetics on intracranial pressure and cerebral perfusion pressure in two feline models of brain edema

PURPOSE

The purpose of this study was to investigate the effects of various intravenous anesthetics on intracranial pressure (ICP) and cerebral perfusion pressure (CPP) in two models of brain edema in a prospective study in a Pediatric critical care animal laboratory in a university hospital.

MATERIALS AND METHODS

Intraparenchymal ICP monitors were inserted in 30 anesthetized adult cats. In 15 cats, an intraparenchymal balloon-tipped catheter was placed and inflated to create a space-occupying lesion (SOL) to mimic vasogenic brain edema (VBE). In the other 15 cats, cytotoxic brain edema (CBE) was created by an acute reduction in blood osmolality. We used continuous hemodiafiltration (CAVH-D) and replaced the ultrafiltrate with hypotonic solution to maintain euvolemia. At predetermined points, each cat in each model received multiple intravenous (i.v.) injections of one of the following medications: methohexital 1.5 mg/kg, propofol 2 mg/kg, or ketamine 2 mg/kg. ICP and mean arterial pressure (MAP) were continuously monitored in all animals.

RESULTS

In the SOL model, all three anesthetic agents decreased ICP after each administration (P < .05). Ketamine administration also resulted in an increase in CPP in this model (P < .05). In the CBE model, none of these agents resulted in a significant change in either ICP or CPP.

CONCLUSIONS

Our results indicate that i.v. anesthetics decrease ICP caused by SOL but have no significant effect on ICP due to CBE. We postulate that in the SOL model, and similarly in VBE, some brain tissue is viable and remains responsive to anesthetics. In contrast, in the CBE model, diffuse intracellular damage occurs, the cerebral metabolic rate may be severely depressed, autoregulation of the cerebral vasculature may be impaired, and unresponsiveness to i.v. anesthetics may occur.

Increased artificial deadspace ventilation is a safe and reliable method for deliberate hypercapnia

OBJECTIVES

To develop a simple method in an animal model to achieve deliberate hypercapnia, which can be used easily and safely to regulate the pulmonary vascular resistance without changing mean airway pressure and compromising oxygenation.

DESIGN

Prospective study, with each animal used as its own control.

SUBJECTS

Minipigs, weighing 11 to 14 kg (n = 7).

INTERVENTIONS

A quadrilumen thermodilution pulmonary artery catheter was placed in minipigs via the internal jugular vein. Systemic blood pressure was measured with use of a femoral arterial catheter. The animals' lungs were ventilated with an FIO2 of 1.0, and a stable state of eucapnia was achieved and maintained for 30 mins. The artificial deadspace was increased every 30 mins, by connecting 45-mL (3- to 4-mL/kg) corrugated tube segments until a total deadspace volume of 180 mL was added.

MEASUREMENTS AND MAIN RESULTS

Hemodynamic performance was evaluated at baseline and after 45 mL (3 to 4 mL/kg), 90 mL (6 to 8 mL/kg), 135 mL (9 to 11 mL/kg), and 180 mL (12 to 15 mL/kg) of added deadspace. Data were indexed to the animal's weight (in kg). Increased artificial deadspace produced a significant (p < .05) increase in PaCO2. These increases in PaCO2 were associated with significant (p < .05) increases of 23%, 32%, 45%, and 46% in the mean pulmonary vascular resistance values, and 6%, 16%, 23%, and 23% in the mean pulmonary arterial pressure, respectively. The systemic pH was decreased from a mean baseline value of 7.45 to 7.39, 7.28, 7.20, and 7.11, respectively. There were no significant changes in PaO2, oxygen consumption, systemic vascular resistance, and cardiac output throughout the experiments.

CONCLUSIONS

A gradual increase in artificial deadspace ventilation produces a state of deliberate hypercapnia. In our animal model, a moderate increase in artificial deadspace significantly increased the pulmonary vascular resistance but was not associated with detrimental respiratory acidemia. Larger volumes of added artificial deadspace had no detrimental effect on cardiac output, oxygen content, oxygen consumption, and systemic vascular resistance, but were associated with significant respiratory acidemia and therefore should be avoided.

Issues of medical necessity: a medical director's guide to good faith adjudication

The term medical necessity is difficult to define, a problem for insurers who need to clearly describe what is and is not covered in their contracts with subscribers. An unclear, vague definition of medical necessity leaves insurers vulnerable to litigation by subscribers denied care deemed medically unnecessary. To avoid lawsuits, insurers must make every effort to educate their subscribers about their medical coverage, going beyond merely providing a lengthy subscriber handbook. In decisions on medical necessity, medical directors at insurance companies play a key role. They can bolster the insurer's position in denial-of-care cases in numerous ways, including keeping meticulous records, eliminating unreasonable financial incentives, maintaining a claims denial database, and consulting with other insurers to achieve a consensus on medical necessity.

Monitoring interactions between spontaneous respiration and mechanical inflations in preterm neonates

OBJECTIVES

To determine the value of a new bedside monitor in assessing the interactions between spontaneous respiratory activity and ventilator inflations in preterm infants; and to monitor continuously the degree of patient-ventilator synchrony and the stability of spontaneous respiratory effort during different modes of ventilation and in response to care procedures.

DESIGN

A prospective, observational study of physiologic variables recorded by a computerized monitoring system.

SETTING

A neonatal intensive care unit in a teaching hospital.

PATIENTS

Thirty-one neonates (median gestational age of 28 wks [range 24 to 36]; median birth weight of 942 g [range 624 to 2940]) were monitored during conventional mandatory ventilation at rates ranging from 47 to 108 inflations/min, and 22 infants (median gestational age of 27.5 wks [range 25 to 40]; median birth weight of 1345 g [range 510 to 3490]) were monitored during patient-triggered ventilation. All infants were sedated as part of the routine care policy.

INTERVENTIONS

Spontaneous respiration (abdominal pressure capsule) and ventilator inflations (airway pressure) were recorded continuously for periods of up to 3 days in mechanically ventilated preterm infants.

MEASUREMENTS AND MAIN RESULTS

The monitoring system uses the Frequency Tracking Locus method to derive the interaction Score, which quantifies the degree of entrainment of the spontaneous respiratory pattern by the ventilator. This analysis was applied to airway pressure and abdominal capsule signals. A perfect 1:1 interaction between spontaneous inspirations and mechanical inflations returns an interaction Score of 1.00, and irregular interactions return a score of > 1.5. During conventional mandatory ventilation, a total of 53,074 16-sec epochs (representing 782,811 spontaneous breaths) were studied in 31 preterm infants: 27.4% of epochs showed a 1:1 interaction, 60.5% a non 1:1 interaction, and 12.1% indicated a passive (i.e., infant apneic) response by the infant, despite excluding periods when paralyzing agents were used. The median interaction Score value during 1:1 interactions was 1.2, whereas for non 1:1 interactions the interaction Score was 2.2. One to one entrainment occurred at conventional mandatory ventilation rates between 50 and 85 inflations/min: for many infants, such entrainment was achievable over a range of conventional mandatory ventilation rates, while in some infants respiration was unstable at all rates of conventional mandatory ventilation. During passive ventilation, the median Interaction Score was 1.0. During patient-triggered mechanical ventilation, approximately 67,150 spontaneous respiratory cycles, represented by 3,592 16-sec epochs, were studied in 22 infants. Overall, 19.5% (702) of epochs showed the criteria for ideal triggering by spontaneous inspiration and 19.6% (703) showed autotriggering. In 60.9% (2187) of epochs, a non 1:1 interaction was noted. During ideal patient-triggered mechanical ventilation, the median interaction Score was 1.14; during passive (autotriggered) ventilation, the median Interaction Score was 1.05; and during non 1:1 ventilation, the median score was 1.74. "Autotriggering" was found frequently in infants of < or = 28 wks gestation. The monitor was able to distinguish between stable and unstable interactions and apnea during conventional mandatory ventilation and patient-triggered mechanical ventilation by reference to the Interaction Score value.

CONCLUSIONS

We describe a new kind of bedside monitor for the Interpretation of respiratory data. Unlike other methods, it is able to give the clinician a continuous measure of patient-ventilator interaction which is easy to interpret. It appears to have wide-spread application in neonatal intensive care nurseries where the babies' own breathing efforts can affect the efficiency of respiration and cause unwanted physiologic instability. The monitor can be used to determine the optimal ventilatory settings to

The self-management of psychiatric medications: a pilot study

This paper reports on a pilot study where a scheme for the self-management of medication has been devised as an intervention strategy, where the mental health nurse and the mentally ill client work together to improve the client's knowledge of prescribed medication and medication-related issues. Aspects of non-compliance and the various factors involved in the non-compliance of psychiatric medications by the person who is severely mentally ill are discussed. When non-compliance to psychiatric medication is briefly examined, the complexity of the phenomena becomes increasingly apparent, confounding single intervention strategies, therefore as the phenomena is multidimensional, so must by any response. A review of the literature, and from the past clinical experience of the authors, suggests that when there is an involved therapeutic alliance, and the active participation of both the client and the mental health nurse in a rehabilitation orientated self-medication management scheme, a difference can occur for the client where their understanding of, and compliance with, psychiatric medication can improve. This could possibly improve the overall quality of life for the mentally ill person. Within a psychosocial rehabilitation setting, a self-medication management scheme has been developed that gradually facilitates the client's responsibility for managing their own prescribed medication, and in conjunction with this increased awareness of their medication and related issues, the focus eventually leads to the client having complete responsibility for managing their own medication. This self-medication management scheme consists of several graded stages that are contractual in nature, in which the clients and nurses are active participants. A rating and self-reporting scale has been developed within the scheme and is used by both the nurse and the client to assist in gauging the client's understanding and knowledge of issues related to their medication use. This self-medication management scheme has demonstrated that when severely mentally ill persons are given the opportunity to practice and manage their own medication as a component of the rehabilitative process, a self-medication management scheme does make a difference.

Defining Collegiality within the Academic Setting

Faculty development and performance are important issues within colleges of nursing. Collegiality is a performance requirement for promotion and tenure, but the behaviors synonymous with collegiality are frequently unwritten within the academic community as well as being poorly defined in the literature. The ambiguity that this situation produces is often experienced by faculty seeking tenure and promotion. Faculty at a midwestern university used the Delphi technique to determine behaviors synonymous with collegiality. Results of the Delphi rounds yielded specific behavioral indicators for the four broad statements that describe collegiality in the governance document of the university. Those statements include willingness to serve on committees and perform work necessary to departmental operations, willingness to provide guidance and help colleagues in their professional duties, respect for the ideas of others, and conduct of one's professional life without prejudice toward others. Findings revealed that while the area of collegiality is ambiguous, indicators of collegial behavior can be identified. Limitations and benefits of using the Delphi technique are discussed.

Breast cancer metastatic to the gastrointestinal tract

The clinical course of patients with breast cancer is often protracted with metastases presenting a considerable time after initial diagnosis and surgical intervention. Whilst specific common patterns of tumour dissemination may be anticipated and readily recognised, more unusual sites may present with confusing symptoms seemingly unconnected to the breast primary. This report documents two cases of primary breast cancer metastatic to the gastrointestinal tract presenting to one surgical unit.

Functional differentiation of dendritic cells in rheumatoid arthritis: role of CD86 in the synovium

Dendritic cells (DC) are the major APC in human peripheral blood (PB) and rheumatoid synovium. We previously identified in PB a population of CD33dim-CD14dim DC precursors, as well as a smaller population of CD33bright CD14dim mature DC. Neither PB DC population expressed the CD28/CTLA4 ligands, suggesting that additional signals are required for full functional DC differentiation. Because rheumatoid synovium is characterized by an ongoing immune response, the expression and function of CD80, CD86, and other markers of DC differentiation by rheumatoid arthritis synovial APC were examined. The phenotype of a large subset of freshly isolated rheumatoid arthritis synovial fluid (SF) DC resembled that of the mature PB DC. These DC expressed CD45R0, CD11c, CMRF-44, and high levels of CD33. Whereas CD80 expression by rheumatoid SF DC and monocytes was minimal, CD86 was expressed by a subset of SF monocytes and by CMRF-44+SF DC. Furthermore, sorted CD86- SF DC spontaneously up-regulated CD86 in vitro. CD80 was expressed diffusely and at low levels by rheumatoid synovial tissue cells, whereas CD86 was expressed by perivascular HLA-DR+HLA-DQ+CD80+CMRF-44+ DC, and by some CD14+ monocytes. Anti-CD86 mAb and CTLA4 Ig, but not anti-CD80 mAb, inhibited the MLR stimulated by SF DC. Both CMRF-44+ and CMRF-44- SF DC were efficient stimulators of the allogeneic MLR, which was in each case blocked by CTLA4 Ig. The data indicate that rheumatoid synovial DC can undergo full functional differentiation, associated with CD86 expression, in vitro and in situ. Synovial DC expressing high levels of MHC molecules and CD86 are strategically located to present arthritogenic Ag to T cells after transendothelial migration.

Functional differentiation of dendritic cells in rheumatoid arthritis: role of CD86 in the synovium

Dendritic cells (DC) are the major APC in human peripheral blood (PB) and rheumatoid synovium. We previously identified in PB a population of CD33dim-CD14dim DC precursors, as well as a smaller population of CD33bright CD14dim mature DC. Neither PB DC population expressed the CD28/CTLA4 ligands, suggesting that additional signals are required for full functional DC differentiation. Because rheumatoid synovium is characterized by an ongoing immune response, the expression and function of CD80, CD86, and other markers of DC differentiation by rheumatoid arthritis synovial APC were examined. The phenotype of a large subset of freshly isolated rheumatoid arthritis synovial fluid (SF) DC resembled that of the mature PB DC. These DC expressed CD45R0, CD11c, CMRF-44, and high levels of CD33. Whereas CD80 expression by rheumatoid SF DC and monocytes was minimal, CD86 was expressed by a subset of SF monocytes and by CMRF-44+SF DC. Furthermore, sorted CD86- SF DC spontaneously up-regulated CD86 in vitro. CD80 was expressed diffusely and at low levels by rheumatoid synovial tissue cells, whereas CD86 was expressed by perivascular HLA-DR+HLA-DQ+CD80+CMRF-44+ DC, and by some CD14+ monocytes. Anti-CD86 mAb and CTLA4 Ig, but not anti-CD80 mAb, inhibited the MLR stimulated by SF DC. Both CMRF-44+ and CMRF-44- SF DC were efficient stimulators of the allogeneic MLR, which was in each case blocked by CTLA4 Ig. The data indicate that rheumatoid synovial DC can undergo full functional differentiation, associated with CD86 expression, in vitro and in situ. Synovial DC expressing high levels of MHC molecules and CD86 are strategically located to present arthritogenic Ag to T cells after transendothelial migration.

Protection of xenogeneic cardiac endothelium from human complement by expression of CD59 or DAF in transgenic mice

We investigated the ability of membrane-bound human complement regulatory proteins to control complement-driven humoral immune reactions on murine microvasculature. The human complement regulatory proteins CD59 and DAF were expressed using heterologous promoters in a variety of tissues in transgenic mice. Animals expressing these gene products are healthy and exhibit significant levels of endothelial cell expression of CD59 and DAF in cardiac muscle. Transgenic hearts perfused with human plasma exhibited profound reductions in the level of complement deposition compared with nontransgenic controls. We have also produced transgenic pigs that express these two human genes. Our results indicate that expression of complement regulatory proteins can control activation of complement and suggest that these proteins may have therapeutic applications in some inflammatory diseases and in the development of xenogeneic organs for human transplantation.

Nursing evaluation of the use of clozapine: an interim progress report

Clozapine, an atypical neuroleptic, has demonstrated some success in the treatment of schizophrenia in clients regarded as treatment resistive. This report gives an overview of clozapine, the indications for and adverse effects of its use. An interim 3 month report of the Rozelle Hospital's nursing evaluation of the use of clozapine follows. This evaluation reports on the subjective experience of four clients during the first 3 months of clozapine treatment. The scales used for the evaluation, the Life Skills Profile (LSP) and the Nurses Observation rating Scale for Inpatient Evaluation (NOSIE-30), assist in measuring change in the clients' functioning and disability. The evaluation, when completed, will offer nurses caring for clients on clozapine a unique body of nursing knowledge.

A comparison of conventional culture and three rapid methods for the detection of Salmonella in poultry feeds and environmental samples

Three rapid methods, an impedance method (Malthus 2000 Analyzer), a colorimetric DNA hybridization method (Gene-Trak) and a post-enrichment enzyme-linked immunosorbent assay (Salmonella-Tek) were compared with conventional culture for the detection of Salmonella in poultry feeds, and in fluff and dust samples from poultry housing. The percentage positive samples for Salmonella by each of the methods were 25.5% for conventional culture, 38.4% for the Malthus, 28.9% for the Gene-Trak and 28.5% for the Salmonella-Tek. By any method 60/153 (39.2%) of the samples tested were positive on confirmed culture.

Apoprotein B-100 production is decreased in subjects heterozygous for truncations of apoprotein B

Among individuals who are heterozygous for familial hypobetalipoproteinemia (FHBL) and who have various truncations of apoprotein (apo) B (ie, FHBL with apoB truncation/apoB-100 genotypes), the plasma concentrations of apoB-100 are typically approximately 30% rather than the expected approximately 50% of those in unaffected family members. The metabolic basis for the low apoB-100 levels is unknown. Therefore, we compared the metabolism of apoB-100 in 8 subjects with heterozygous FHBL (2 apoB-89/apoB-100, 2 apoB-75/apoB-100, 2 apoB-54.8/apoB-100, 1 apoB-52/apoB-100, and 1 apoB-31/apoB-100) with the metabolism of apoB-100 in 8 apoB-100/apoB-100 control subjects who were paired with the heterozygotes by gender, age, height, weight, and race. Endogenous labeling of apoB-100 with [13C]leucine and a multicompartmental kinetic model were used to obtain kinetic parameters. FHBL heterozygotes had significantly reduced VLDL apoB-100 production rates (7.7 +/- 3.7 versus 21.2 +/- 6.2 mg.kg-1.d-1, P = .002) and LDL apoB-100 production rates (4.5 +/- 3.12 versus 15.3 +/- 1 mg.kg-1.d-1, P = .05) compared with control subjects. Fractional conversion rates of VLDL to LDL were not significantly different (0.67 +/- 0.36 versus 0.77 +/- 0.17 pools/d), and the respective fractional catabolic rates of apoB-100 in VLDL, IDL, and LDL also were similar in both groups. Thus, FHBL heterozygotes produced apoB-100 at about 30% of the rates of control subjects. We believe these reduced production rates largely account for the lower than expected levels of apoB-100 and LDL cholesterol in the plasma of FHBL heterozygotes.

A disposable-chamber temperature-regulation system for the study of intracellular calcium levels in single live T cells using fluorescence digital-imaging microscopy

Utilizing flow cytometry, we previously demonstrated that the potassium channel blocker margatoxin (MgTX) inhibits the [Ca2+]i transient involved in T-cell activation. We wished to extend these studies to single-cell transients using florescence digital-imaging microscopy (DIM). However, the most currently available temperature-regulation chambers reuse part or all of the apparatus and introduce compounds via perfusion. Thus, these apparatuses are not suitable for studies involving compounds that are particularly sticky. We have designed a dual-temperature regulation system that will maintain Nunc, eight-well, coverglass-bottom, disposable chambers, and three disposable addition pipets at 37 degrees C for physiological studies on an inverted digital-imaging microscope. We have demonstrated that calcium transients of human T lymphocytes can be initiated and monitored reproducibly during the addition of three distinct chemical species. The DIM results correlate with flow cytometry measurements in the number of responding cells and the heterogeneity of the response in both control and MgTX-inhibited cultures. Additionally, DIM revealed that the [Ca2+]i transient is more rapid than the flow-cytometric measurement indicated. The correlation between flow cytometry and DIM permits the amalgamation of these results in the interpretation of studies on the regulation of T-cell activation.

Diagnosis of bovine venereal campylobacteriosis by ELISA

An enzyme-linked immunosorbent assay (ELISA) measuring IgA antibodies in the vaginal mucus was used to diagnose bovine venereal campylobacteriosis in 241 herds with infertility and abortions. The presence of the disease was confirmed on 84 farms (34.8%) and it was suspected on a further 27 farms (11.2%). The specificity of the ELISA was found to be 98.5% but in the absence of a reliable comparative test sensitivity can not be estimated. Vaccination against campylobacteriosis will not interfere with the IgA ELISA because only IgG is present in the vaginal mucus of vaccinates. Because of the possibility of false reactions caused by antibody fluctuations in individual cattle, the ELISA is best used as a herd test. It appears that at present the vaginal mucus IgA ELISA is the test of choice for the diagnosis of bovine venereal campylobacteriosis.

Influence of inflammation and atrophy on pancreatic secretory trypsin inhibitor levels within the gastric mucosa

BACKGROUND/AIMS

Gastrointestinal epithelia contain a powerful protease inhibitor called pancreatic secretory trypsin inhibitor (PSTI). Gastric mucus obtained from patients with atrophic gastritis or gastric ulceration shows changes suggestive of excessive proteolytic digestion. Therefore, the aim of this study was to examine whether mucosal PSTI levels are affected by gastritis and/or ulceration.

METHODS

Mucosal PSTI levels were measured in 12 patients with normal gastric histology and 26 patients with gastritis and/or gastric ulceration.

RESULTS

In control subjects, mean gastric PSTI concentrations were 990 ng/mg protein (95% confidence interval, 819-1195) in the antrum and 445 ng/mg protein (95% confidence interval, 395-502) in the body. Immunostaining for PSTI was strongly positive in the pyloric glands of the antrum and in the foveolar/surface and mucus neck cells of the gastric body. Tissue levels of PSTI were reduced by 40% in biopsy specimens showing superficial gastritis (P = 0.035) and by 75% in biopsy specimens showing atrophic gastritis and/or gastric ulceration (P < 0.001). Immunostaining was also reduced in specimens showing atrophic gastritis.

CONCLUSIONS

The decrease in tissue PSTI levels associated with gastric atrophy probably represents a permanent reduction in one of the mucosal defense mechanisms. This may lead to the maintenance and even expansion of the gastritic process with time.

Efficacy of psyllium in reducing serum cholesterol levels in hypercholesterolemic patients on high- or low-fat diets

OBJECTIVES

To determine the efficacy of psyllium in reducing serum cholesterol levels in patients on high- or low-fat diets.

DESIGN

Double-blind, placebo-controlled, 16-week parallel trial. The study included an 8-week baseline period and an 8-week treatment period.

PATIENTS

Healthy men and women, 21 to 70 years old, with primary hypercholesterolemia (total serum cholesterol > or = 5.7 mmol/L [220 mg/dL]). Thirty-seven participants followed a high-fat diet and 81 participants followed a low-fat diet.

INTERVENTION

Participants were randomly assigned to either psyllium, 5.1 g twice a day, or placebo.

MEASUREMENTS

Fasting lipid and apolipoprotein concentrations, including direct low-density lipoprotein (LDL) cholesterol quantification; nutritional analyses of 4 days of 7-day food records to monitor dietary compliance; and physical examinations, clinical chemistry and hematologic studies, and urinalysis to assess treatment safety.

MAIN RESULTS

Psyllium recipients in both the high- and low-fat diet groups showed small but significant decreases (P < 0.05) in total cholesterol and low-density lipoprotein (LDL) cholesterol levels. Total cholesterol and LDL cholesterol levels decreased 5.8% and 7.2%, respectively, in psyllium recipients on high-fat diets and 4.2% and 6.4%, respectively, in psyllium recipients on low-fat diets. No significant difference was seen in LDL cholesterol response when psyllium recipients on low- and high-fat diets were compared (P > 0.2). No significant reductions in lipid levels were observed in placebo recipients. Based on the National Cholesterol Education Program LDL cholesterol classification system, 39% of the psyllium recipients improved in LDL cholesterol classification (P < 0.0001) compared with 20.3% of placebo recipients (P > 0.2).

CONCLUSIONS

Psyllium produces a modest but significant improvement in total cholesterol and LDL cholesterol levels in persons on either low-fat or high-fat diets. Psyllium, when added to a prescribed low-fat diet, may obviate the need for typical lipid-lowering medications or may prove to be a valuable adjunct to other treatments in patients with moderately elevated LDL cholesterol levels.