Design of paediatric trials with benefit-risk endpoints using a composite score of adverse events of interest (AEI) and win-statistics

A fundamental problem in the regulatory evaluation of a therapy is assessing whether the benefit outweighs the associated risks. This work proposes designing a trial that assesses a composite endpoint consisting of benefit and risk, hence, making the core of the design of the study, to assess benefit and risk. The proposed benefit risk measure consists of efficacy measure(s) and a risk measure that is based on a composite score obtained from pre-defined adverse events of interest (AEI). This composite score incorporates full aspects of adverse events of interest (i.e. the incidence, severity, and duration of the events). We call this newly proposed score the AEI composite score. After specifying the priorities between the components of the composite endpoint, a win-statistic (i.e. win ratio, win odds, or net benefit) is used to assess the difference between treatments in this composite endpoint. The power and sample size requirements of such a trial design are explored via simulation. Finally, using Dupixent published adult study results, we show how we can design a paediatric trial where the primary outcome is a composite of prioritized outcomes consisting of efficacy endpoints and the AEI composite score endpoint. The resulting trial design can potentially substantially reduce sample size compared to a trial designed to assess the co-primary efficacy endpoints, therefore it may address the challenge of slow enrollment and patient availability for paediatric studies.

Improving the Utilization of STRmix™ Variance Parameters as Semi-Quantitative Profile Modeling Metrics

Distributions of the variance parameter values developed during the validation process. Comparisons of these prior distributions to the run-specific average are one measure used by analysts to assess the reliability of a STRmix deconvolution. This study examined the behavior of three different STRmix variance parameters under standard amplification and interpretation conditions, as well as under a variety of challenging conditions, with the goal of making comparisons to the prior distributions more practical and meaningful. Using information found in STRmix v2.8 Interpretation Reports, we plotted the log₁₀ of each variance parameter against the log₁₀ of the template amount of the highest-level contributor (Tc) for a large set of mixture data amplified under standard conditions. We observed nonlinear trends in these plots, which we regressed to fourth-order polynomials, and used the regression data to establish typical ranges for the variance parameters over the Tc range. We then compared the typical variance parameter ranges to log₁₀(variance parameter) v log₁₀(Tc) plots for mixtures amplified and interpreted under a variety of challenging conditions. We observed several distinct patterns to variance parameter shifts in the challenged data interpretations in comparison to the unchallenged data interpretations, as well as distinct shifts in the unchallenged variance parameters away from their prior gamma distribution modes over specific ranges of Tc. These findings suggest that employing empirically determined working ranges for variance parameters may be an improved means of detecting whether aberrations in the interpretation were meaningful enough to trigger greater scrutiny of the electropherogram and genotype interpretation.

Communicating risk to promote colorectal cancer screening: a multi-method study to test tailored versus targeted message strategies

Colorectal cancer (CRC) screening rates are suboptimal, partly due to poor communication about CRC risk. More effective methods are needed to educate patients, but little research has examined best practices for communicating CRC risk. This multi-method study tests whether tailoring CRC risk information increases screening intentions. Participants (N = 738) were randomized with a 2:2:1 allocation to tailored, targeted, and control message conditions. The primary outcome was intention to screen for CRC (yes/no). Additional variables include perceived message relevance, perceived susceptibility to CRC, and free-text comments evaluating the intervention. A chi-square test determined differences in the proportion of participants who intended to complete CRC screening by condition. A logistic-based path analysis explored mediation. Free-text comments were analyzed using advanced topic modeling analysis. CRC screening intentions were highest in the tailored intervention and significantly greater than control (P = 0.006). The tailored message condition significantly increased message relevance compared with control (P = 0.027) and targeted conditions (P = 0.002). The tailored condition also increased susceptibility (P < 0.001) compared with control, which mediated the relationship between the tailored condition and intention to screen (b = 0.04, SE = 0.02, 95% confidence interval = 0.02, 0.09). The qualitative data reflect similar trends. The theoretical mechanisms and practical implications of tailoring health education materials about CRC risk are discussed.

Critical care usage after major gastrointestinal and liver surgery: a prospective, multicentre observational study

BACKGROUND

Patient selection for critical care admission must balance patient safety with optimal resource allocation. This study aimed to determine the relationship between critical care admission, and postoperative mortality after abdominal surgery.

METHODS

This prespecified secondary analysis of a multicentre, prospective, observational study included consecutive patients enrolled in the DISCOVER study from UK and Republic of Ireland undergoing major gastrointestinal and liver surgery between October and December 2014. The primary outcome was 30-day mortality. Multivariate logistic regression was used to explore associations between critical care admission (planned and unplanned) and mortality, and inter-centre variation in critical care admission after emergency laparotomy.

RESULTS

Of 4529 patients included, 37.8% (n=1713) underwent planned critical care admissions from theatre. Some 3.1% (n=86/2816) admitted to ward-level care subsequently underwent unplanned critical care admission. Overall 30-day mortality was 2.9% (n=133/4519), and the risk-adjusted association between 30-day mortality and critical care admission was higher in unplanned [odds ratio (OR): 8.65, 95% confidence interval (CI): 3.51-19.97) than planned admissions (OR: 2.32, 95% CI: 1.43-3.85). Some 26.7% of patients (n=1210/4529) underwent emergency laparotomies. After adjustment, 49.3% (95% CI: 46.8-51.9%, P<0.001) were predicted to have planned critical care admissions, with 7% (n=10/145) of centres outside the 95% CI.

CONCLUSIONS

After risk adjustment, no 30-day survival benefit was identified for either planned or unplanned postoperative admissions to critical care within this cohort. This likely represents appropriate admission of the highest-risk patients. Planned admissions in selected, intermediate-risk patients may present a strategy to mitigate the risk of unplanned admission. Substantial inter-centre variation exists in planned critical care admissions after emergency laparotomies.

Symmetry analysis of talus bone: A Geometric morphometric approach

OBJECTIVE

The main object of this study was to use a geometric morphometric approach to quantify the left-right symmetry of talus bones.

METHODS

Analysis was carried out using CT scan images of 11 pairs of intact tali. Two important geometric parameters, volume and surface area, were quantified for left and right talus bones. The geometric shape variations between the right and left talus bones were also measured using deviation analysis. Furthermore, location of asymmetry in the geometric shapes were identified.

RESULTS

Numerical results showed that talus bones are bilaterally symmetrical in nature, and the difference between the surface area of the left and right talus bones was less than 7.5%. Similarly, the difference in the volume of both bones was less than 7.5%. Results of the three-dimensional (3D) deviation analyses demonstrated the mean deviation between left and right talus bones were in the range of -0.74 mm to 0.62 mm. It was observed that in eight of 11 subjects, the deviation in symmetry occurred in regions that are clinically less important during talus surgery.

CONCLUSIONS

We conclude that left and right talus bones of intact human ankle joints show a strong degree of symmetry. The results of this study may have significance with respect to talus surgery, and in investigating traumatic talus injury where the geometric shape of the contralateral talus can be used as control. Cite this article: Bone Joint Res 2014;3:139-45.

Ethanol-response genes and their regulation analyzed by a microarray and comparative genomic approach in the nematode Caenorhabditis elegans

The nematode shows responses to acute ethanol exposure that are similar to those observed in humans, mice, and Drosophila, namely hyperactivity followed by uncoordination and sedation. We used in this report the nematode Caenorhabditis elegans as a model system to identify and characterize the genes that are affected by ethanol exposure and to link those genes functionally into an ethanol-induced gene network. By analyzing the expression profiles of all C. elegans ORFs using microarrays, we identified 230 genes affected by ethanol. While the ethanol response of some of the identified genes was significant at early time points, that of the majority was at late time points, indicating that the genes in the latter case might represent the physiological consequence of the ethanol exposure. We further characterized the early response genes that may represent those involved directly in the ethanol response. These genes included many heat shock protein genes, indicating that high concentration of ethanol acts as a strong stress to the animal. Interestingly, we identified two non-heat-shock protein genes that were specifically responsive to ethanol. glr-2 was the only glutamate receptor gene to be induced by ethanol. T28C12.4, which encodes a protein with limited homology to human neuroligin, was also specific to ethanol stress. Finally, by analyzing the promoter regions of the early response genes, we identified a regulatory element, TCTGCGTCTCT, that was necessary for the expression of subsets of ethanol response genes.

Constant infusion of epinephrine, but not bolus treatment, improves haemodynamic recovery in anaphylactic shock in dogs

OBJECTIVE

Epinephrine (Epi) is the treatment of choice for reversing cardiovascular collapse in anaphylactic shock (AS). In this condition, most treatment guidelines have been anecdotally derived and no randomized clinical trials have been conducted. In the present study, we examined the time course of haemodynamic recovery in a canine model of AS when Epi was administered at the initiation of allergen challenge before fully developed shock had occurred.

METHODS

Randomized, controlled, crossover studies were performed approximately 3-5 weeks apart in ragweed-sensitized dogs while the animals were ventilated and anaesthetized. Epi was administered by bolus intravenous (i.v.), subcutaneous (s.c.), intramuscular (i.m.) routes and by continuous i.v. infusion (CI). The findings obtained in the Epi treatment (T) studies were compared with those found in a no treatment (NT) study. In the bolus studies, Epi was administered at 0.01 mg/kg, while in the CI study, the dose of Epi was titrated to maintain mean arterial pressure (MAP) at 70% of preshock levels. MAP, cardiac output (CO), stroke volume (SV), and pulmonary wedge pressure (Pwp) were determined over a 3 h period.

RESULTS

In the CI study, haemodynamics (CO, MAP, and SV) were significantly higher than those measured in the NT study and the bolus studies over approximately the first hour of the study. In the CI study, the amount of Epi infused was significantly less than in the bolus studies.

CONCLUSION

When administered at the initiation of allergen challenge, bolus treatment of Epi by i.m., i.v., or s.c. routes caused limited haemodynamic improvement in AS. In contrast, constant infusion of Epi at a lower total dose produced significant haemodynamic improvement. Within the limits of this anaesthetized canine model, the results suggest that CI should be the preferred route in the treatment of AS when this treatment option is available.

Gene expression analysis in a transgenic Caenorhabditis elegans Alzheimer's disease model

We have engineered transgenic Caenorhabditis elegans animals to inducibly express the human beta amyloid peptide (Abeta). Gene expression changes resulting from Abeta induction have been monitored by cDNA hybridization to glass slide microarrays containing probes for almost all known or predicted C. elegans genes. Using statistical criteria, we have identified 67 up-regulated and 240 down-regulated genes. Subsets of these regulated genes have been tested and confirmed by quantitative RT-PCR. To investigate whether genes identified in this model system also show gene expression changes in Alzheimer's disease (AD) brain, we have also used quantitative RT-PCR to examine in post-mortem AD brain tissue transcript levels of alphaB-crystallin (CRYAB) and tumor necrosis factor-induced protein 1 (TNFAIP1), human homologs of genes found to be robustly induced in the transgenic C. elegans model. Both CRYAB and TNFAIP1 show increased transcript levels in AD brains, supporting the validity of this approach.

Identification and characterization of peptide probes directed against PKCalpha conformations

Phage display is a powerful technology that allows identification of high affinity peptides that bind specifically to a given molecular target. Using a highly complex peptide display library, we have identified separate classes of peptides that bind to protein kinase C alpha (PKCalpha) only under activation conditions. Furthermore, peptide binding was specific to PKCalpha and not to any of the other closely related PKC isoforms. The conformational and isoform specificity of the peptide binding was demonstrated using surface plasmon resonance as well as time-resolved fluorescence assays. Kinase assays showed that these peptides were not direct substrates for PKC nor did they inhibit phosphorylation of PKC substrates. These peptides are most likely directed against protein-protein interaction sites on PKC. The data presented here offers another example of application of phage display technology to identify conformation-dependent peptide probes against therapeutically important drug targets. These peptides are ideally suited to be used as surrogate ligands to identify compounds that bind specifically to PKCalpha, as well as conformational probes to detect activated forms of PKCalpha.

Transcriptional profile of aging in C. elegans

BACKGROUND

Numerous gerontogene mutants leading to dramatic life extensions have been identified in the nematode Caenorhabditis elegans over the last 20 years. Analysis of these mutants has provided a basis for understanding the mechanisms driving the aging process(es). Several distinct mechanisms including an altered rate of aging, increased resistance to stress, decreased metabolic rate, or alterations in a program causing organismic aging and death have been proposed to underlie these mutants.

RESULTS

Whole-genome analysis of gene expression during chronological aging of the worm provides a rich database of age-specific changes in gene expression and represents one way to distinguish among these models. Using a rigorous statistical model with multiple replicates, we find that a relatively small number of genes (only 164) show statistically significant changes in transcript levels as aging occurs (<1% of the genome). Expression of heat shock proteins decreases, while expression of certain transposases increases in older worms, and these findings are consistent with a higher mortality risk due to a failure in homeostenosis and destabilization of the genome in older animals. Finally, a specific subset of genes is coordinately altered both during chronological aging and in the transition from the reproductive form to the dauer, demonstrating a mechanistic overlap in aging between these two processes.

CONCLUSIONS

We have performed a whole-genome analysis of changes in gene expression during aging in C. elegans that provides a molecular description of C. elegans senescence.

A global analysis of Caenorhabditis elegans operons

The nematode worm Caenorhabditis elegans and its relatives are unique among animals in having operons. Operons are regulated multigene transcription units, in which polycistronic pre-messenger RNA (pre-mRNA coding for multiple peptides) is processed to monocistronic mRNAs. This occurs by 3' end formation and trans-splicing using the specialized SL2 small nuclear ribonucleoprotein particle for downstream mRNAs. Previously, the correlation between downstream location in an operon and SL2 trans-splicing has been strong, but anecdotal. Although only 28 operons have been reported, the complete sequence of the C. elegans genome reveals numerous gene clusters. To determine how many of these clusters represent operons, we probed full-genome microarrays for SL2-containing mRNAs. We found significant enrichment for about 1,200 genes, including most of a group of several hundred genes represented by complementary DNAs that contain SL2 sequence. Analysis of their genomic arrangements indicates that >90% are downstream genes, falling in 790 distinct operons. Our evidence indicates that the genome contains at least 1,000 operons, 2 8 genes long, that contain about 15% of all C. elegans genes. Numerous examples of co-transcription of genes encoding functionally related proteins are evident. Inspection of the operon list should reveal previously unknown functional relationships.

Study of patient positioning on a dynamic frame for scoliosis surgery

The goal of this clinical trial was to measure patient geometry on a dynamic positioning frame in various prone positions. Fourteen subjects (2 males and 12 females) were recruited from the scoliosis clinic at Ste-Justine Hospital on a volunteer basis. The subjects were AIS patients who were potential candidates for surgery. The Cobb angle, averaged 50 degrees (32 degrees-64 degrees). The mean age was 14.1 years (11-17). A Polaris system (Northern Digital inc, Canada) with 10 passive reflective markers was used to measure various indices of the patient's trunk geometry. Acquisitions were made while the unanaesthetized patient was in five different prone positions: I similar to the standard positioning on a Relton-Hall frame; II addition of a force applied to the ribcage at the apex of the curve; III application of a force at the apex of the curve in the lumbar region; IV, the shoulder pads were elevated to increase the patient's kyphosis; V adjustment of each pad and the application of thoracic and lumbar forces to obtain an optimal correction. The measurements of trunk geometry at each position were compared using position I as a base. A paired student t-test determined a significant difference between positions. When comparing position I to position II there was a significant difference and correction of the rib hump. There was also a significant change in shoulder angle that resulted in over correction. Position III had a significantly negative change in the rib hump. During position IV, there was a measurable increase in kyphosis. During the optimal correction, position V, a significant increase in spine length was observed as well as a significant correction in rib hump and shoulder angle. Patient trunk geometry can be improved by the application of different forces on a dynamic positioning frame. Caution is necessary as over correction and unintended negative effects were observed. The optimal patient position has not yet been found and future studies are directed at determining this.

A gene expression map for Caenorhabditis elegans

We have assembled data from Caenorhabditis elegans DNA microarray experiments involving many growth conditions, developmental stages, and varieties of mutants. Co-regulated genes were grouped together and visualized in a three-dimensional expression map that displays correlations of gene expression profiles as distances in two dimensions and gene density in the third dimension. The gene expression map can be used as a gene discovery tool to identify genes that are co-regulated with known sets of genes (such as heat shock, growth control genes, germ line genes, and so forth) or to uncover previously unknown genetic functions (such as genomic instability in males and sperm caused by specific transposons).

Genome-wide analysis of developmental and sex-regulated gene expression profiles in Caenorhabditis elegans

We have constructed DNA microarrays containing 17,871 genes, representing about 94% of the 18,967 genes currently annotated in the Caenorhabditis elegans genome. These DNA microarrays can be used as a tool to define a nearly complete molecular profile of gene expression levels associated with different developmental stages, growth conditions, or worm strains. Here, we used these full-genome DNA microarrays to show the relative levels of gene expression for nearly every gene during development, from eggs through adulthood. These expression data can help reveal when a gene may act during development. We also compared gene expression in males to that of hermaphrodites and found a total of 2,171 sex-regulated genes (P < 0.05). The sex-regulated genes provide a global view of the differences between the sexes at a molecular level and identify many genes likely to be involved in sex-specific differentiation and behavior.

Impaired sarcoplasmic calcium release inhibits myocardial contraction in experimental sepsis

PURPOSE

In septic shock, myocardial dysfunction develops over the course of illness, but the mechanism of this depression is not clear. In this study, mechanisms of myocardial dysfunction were examined in a porcine model of Escherichia coli sepsis.

MATERIALS AND METHODS

Animals were subjected to 4 hours of bacteria infusion (n = 5) (septic group) or saline infusion (n = 5) (nonseptic group), after which trabeculae were removed from the right ventricle and placed into a recirculating water bath. Measurements of steady-state contraction (SSC) were obtained at 0.5, 1, and 2 Hz. Indirect indices were used to assess abnormalities in myocardial calcium metabolism in sepsis. Extrasystoles (ES) were used to assess transsarcolemmal (TSL) calcium flux and were measured at 300 milliseconds, 400 milliseconds, and 500 milliseconds after the preceding stimulus. Postrest contraction (PRC) is an indicator of SR recirculation from the uptake to the release site and was obtained after interposing intervals of rest between steady-state beats at 0.5 Hz. Rapid-cooling contracture (RCC) is an indicator of sarcoplasmic reticulum (SR) content and was obtained at 0.5, 1, and 2 Hz and after interposing intervals of rest at 0.5 Hz.

RESULTS

SSC was not different between groups at 0.5 Hz, but compared with the nonseptic group, SSC decreased at 1 and 2 Hz in the septic group (P < .05). PRC and TSL were not different between groups. During rest intervals, calcium leaks out of SR through the ryanodine channel (ie, SR calcium release channel). In the septic group, as assessed by RCC, SR calcium leak was less than that found in the nonseptic group.

CONCLUSION

These results indicate that myocardial dysfunction in sepsis is frequency dependent, and that the mechanism is most likely caused by inhibition of SR calcium release owing to blockade of the ryanodine channel.

Redox chemistry in laccase-catalyzed oxidation of N-hydroxy compounds

1-Hydroxybenzotriazole, violuric acid, and N-hydroxyacetanilide are three N-OH compounds capable of mediating a range of laccase-catalyzed biotransformations, such as paper pulp delignification and degradation of polycyclic hydrocarbons. The mechanism of their enzymatic oxidation was studied with seven fungal laccases. The oxidation had a bell-shaped pH-activity profile with an optimal pH ranging from 4 to 7. The oxidation rate was found to be dependent on the redox potential difference between the N-OH substrate and laccase. A laccase with a higher redox potential or an N-OH compound with a lower redox potential tended to have a higher oxidation rate. Similar to the enzymatic oxidation of phenols, phenoxazines, phenothiazines, and other redox-active compounds, an "outer-sphere" type of single-electron transfer from the substrate to laccase and proton release are speculated to be involved in the rate-limiting step for N-OH oxidation.

Impaired hepatic extraction and increased splanchnic production contribute to lactic acidosis in canine sepsis

In septic shock, the extent to which lactic acidosis (LA) is a consequence of splanchnic lactate overproduction (SLP) or impaired hepatic lactate extraction (HLE) is not clear. We examined SLP and HLE in E. coli sepsis in dogs. We further determined the effects of vasopressor treatments, which included phenylephrine, dopamine, norepinephrine, and a combination of dobutamine and norepinephrine treatment, on SLP and HLE in respective groups. The animals were studied while anesthetized and ventilated. During sepsis, SLP increased as compared with presepsis (-0.017 versus 0.07 mmol/min, p < 0.05), but this increase could not be explained by reduced splanchnic oxygen delivery (SOD). During sepsis, HLE increased as compared with baseline (0.8 versus 8%, p < 0.05), but was significantly lower than that found during lactic acid loading in nonseptic dogs. None of the vasopressor treatments had a detrimental effect on SLP. These results indicate that LA in sepsis occurs secondary to an increase in splanchnic lactate production that is not related to reduced splanchnic oxygen delivery, as well as to a decrease in hepatic lactate extraction. Effects of different vasoactive agents did not alter either splanchnic lactate production or hepatic lactate extraction in this sepsis model.

Histamine H3 receptor blockade improves cardiac function in canine anaphylaxis

In anaphylactic shock (AS), the relative effects of the autacoids including histamine, prostaglandins, and leukotrienes on causing cardiovascular collapse and the extent to which receptor blocking agents and pathway inhibitors may prevent this collapse are not clear. In a ragweed model of anaphylaxis, we examined whether pretreatment with H1, H2, H3 receptor blockers, and cyclooxygenase and leukotriene pathway inhibitors was useful in preventing the depression in left ventricular (LV) contractility known to occur in this model. The dose of allergen was varied to produce similar degrees of shock between treatments. The animals were studied under pentobarbital anesthesia in which the treatment studies were approximately 3 wk apart. LV volumes were measured by sonomicrometric techniques. During challenge, mean arterial blood pressure (Pa), cardiac output (Q), and LV end-diastolic pressure (LVEDP) decreased approximately 50% compared with preshock values in all treatments. Histamine H3 receptor blockade was associated with higher heart rates (HR) and higher stroke work (SW) (p < 0.05) as compared with the other treatment studies. We conclude that histamine H3 activation by inhibiting adrenergic neural norepinephrine release contributes to cardiovascular collapse in AS.

Role of autacoids in cardiovascular colapse in anaphylactic shock in anaesthetized dogs

OBJECTIVE

In anaphylactic shock (AS), the relative effects of the autacoids including histamine, prostaglandins (prost), and leukotrienes (leuk) on causing cardiovascular collapse and the extent to which receptor blocking agents and pathway inhibitors may prevent this collapse are not clear.

METHODS

In randomized design, we investigated whether blockade of histamine H1, H2, and H3 receptors or inhibition of the cyclooxygenase (cyclo) and lipoxygenase pathways (lipox) prevented AS in ragweed sensitized dogs. Seven dogs were studied under pentobarbital anesthesia in which the treatment studies were approximately 2 weeks apart.

RESULTS

During H1 receptor blockade, the decreases in blood pressure and cardiac output otherwise observed in AS were attenuated (P < 0.05) and the release of prost, thromboxanes, and leuk were reduced as compared with nontreatment studies. Cyclo inhibition also attenuated cardiovascular collapse and mediator release in AS, but the other treatments showed no effects.

CONCLUSION

H1 receptor blockade and cyclo may attenuate cardiovascular shock in AS. These agents inhibit autacoid release from mast cells in addition to any specific receptor blocking and pathway inhibition effects.

Roller traction: mobilizing patients with acetabular fractures

Patients with acetabular fractures unamenable to open reduction and internal fixation are subject to 6-12 weeks of traction and, traditionally, bed rest. Using roller traction allows the patient to be mobilized to a bedside chair and to stand without disrupting the traction. This is accomplished by slightly modifying a standard lower extremity skeletal traction setup. Roller pulleys and stopper clamps are substituted for the usual pulleys. These are attached to extra-long horizontal bars that expand the lateral space that the patient can now use around the bed. Roller traction helps prevent the common complications of prolonged bed rest, particularly deep vein thrombosis, skin breakdown, pulmonary stasis and boredom.

Timing and interpretation of the hemodynamic effects of the pneumatic antishock garment

STUDY OBJECTIVES

To clarify apparently conflicting reports on the hemodynamic effects of the pneumatic antishock garment (PASG).

DESIGN

Ten anesthetized dogs with hemorrhagic hypotension had hemodynamics measured without PASG inflation (group 1) and were compared with ten dogs with PASG inflation (group 2).

MEASUREMENTS AND MAIN RESULTS

Baseline and immediate posthemorrhage data were similar in both groups. Group 1 maintained a carotid artery pressure of 85 +/- 9 mm Hg while group 2, by design, maintained baseline CP at 119 +/- 12 mm Hg. After PASG inflation, carotid artery flow increased by 50%, and femoral artery flow decreased tenfold. There was an immediate but transient increase (2.4 +/- 0.1 to 2.7 +/- 0.1 L/min, P less than .05) and a later decrease in cardiac output to 1.9 +/- 0.9 L/min and an increased pulmonary artery wedge pressure and central venous pressure over one hour. Saline (342 +/- 12 mL) reversed the decreased cardiac output without changing pulmonary artery wedge pressure or central venous pressure.

CONCLUSION

PASG inflation, therefore, not only increases venous return and cardiac output initially by compressive venous emptying but also decreases venous return and cardiac output later by further venous compression without cardiac decompensation. Thus, apparently conflicting data are explained by the timing and interpretation of the raw hemodynamic measurements.

Pneumatic antishock garment decreases hemorrhage and mortality from splenic injury

The effect of the pneumatic antishock garment (PASG) in controlling hemorrhage and death from splenic injury was studied in a canine model. Twelve (two groups of 6) anesthetized dogs had their spleens crushed. Carotid blood pressure, carotid blood flow, splenic artery flow and abdominal aortic flow, as well as the death rate and blood loss, were measured. Group 1 dogs did not have PASG inflation, but group 2 dogs had PASG inflation to an intraperitoneal pressure of 60 mm Hg. All group 1 dogs died within 27 to 58 minutes, but all group 2 dogs survived. Blood loss was 9.4 +/- 1.4 mL/min in group 1 and 1.6 +/- 0.9 mL/min in group 2. In group 1 carotid artery blood pressure, carotid artery flow, splenic artery flow and abdominal aortic flow fell from 120 +/- 10 mm Hg, 284 +/- 12 mL/min, 194 +/- 18 mL/min and 285 +/- 10 mL/min respectively to 0 with death of the animals. By 2 hours in group 2 dogs the carotid artery blood pressure had dropped from 116 +/- 12 to 99 +/- 12 mm Hg, and over the same period carotid artery flow, splenic artery flow and abdominal aortic flow fell from 296 +/- 8 mL/min, 190 +/- 26 mL/min and 279 +/- 16 mL/min respectively to 259 +/- 14 mL/min, 39.0 +/- 6 mL/min and 45 +/- 11 mL/min respectively. Thus, inflation of the PASG maintained carotid artery blood pressure wh ile decreasing splenic, abdominal and aortic flow as well as splenic hemorrhage, with a decrease in the death rate, over a 2-hour period.

Colloid osmotic pressure in pulmonary edema clearance with furosemide

After tripling of baseline lung water (EVLW), decreasing wedge pressure (PWP) alone for two hours did not decrease EVLW. In 11 of 16 dogs, triple baseline EVLW and a decrease in plasma colloid osmotic pressure (COP) from 21.1 +/- 0.8 to 17.8 +/- 0.8 mm Hg resulted from left atrial balloon inflation at PWP of 28 to 30 mm Hg. With subsequent lowering of PWP to 10 mm Hg, intravenously administered furosemide (1 mg/kg) was given to these 11 dogs. One half hour after furosemide, shunt decreased slightly without decreasing EVLW in all 11 dogs, but by two hours, seven dogs (group 1) decreased EVLW (from 23.2 +/- 1.8 to 11.1 +/- 1.4 ml/kg) and shunt (37.4 +/- 2.0 to 12.9 +/- 2.9 percent), while four dogs (group 2) did not (EVLW: 22.3 +/- 1.4 to 22.5 +/- 0.6 ml/kg: shunt, 36.8 +/- 1.7 to 36.5 +/- 1.9 percent). Group 1 had diuresis, maintained normal blood urea nitrogen and creatinine levels, and increased COP from 17.7 +/- 0.7 to 23.6 +/- 0.5 mm Hg while group 2 was oliguric with elevated BUN and creatinine values and showed no change in COP (17.9 +/- 0.9 to 18.3 +/- 0.6 mm Hg) after furosemide. After decreasing PWP in massive pulmonary edema (triple baseline EVLW), furosemide appeared to enhance edema clearance by changes in COP with diuresis.

Does indomethacin affect shunt and its response to PEEP in oleic acid pulmonary edema?

We assessed hemodynamics, lobar perfusion, and shunts at base line 1.5 h after unilobar oleic acid edema, 15 min after indomethacin (10 mg/kg iv), and 15 min after positive end-expiratory pressure (PEEP) (10 cm) in 10 dogs. In 10 additional dogs (control) the same measurements were made but no indomethacin was administered. Shunts of the edematous lobe were: 10.6 +/- 6.3, 54.1 +/- 22.8, 30.8 +/- 16.6, and 12.4 +/- 6.3% for dogs administered indomethacin and 10.9 +/- 4.2, 53.8 +/- 13.1, 72.3 +/- 14.6, and 11.5 +/- 4.1% for the controls. Perfusions (% cardiac output) to the edematous lobe were 27.6 +/- 3.6, 14.6 +/- 2.0, 9.9 +/- 1.5, and 27.9 +/- 2.9% in the dogs administered indomethacin and 27.3 +/- 3.1, 14.0 +/- 1.7, 13.2 +/- 1.3, and 26.9 +/- 2.8% in controls. The decrease in lobar perfusion was similar before indomethacin with a further decrease in lobar perfusion and an increase in lobar vascular resistance 15 min after indomethacin. The increase in vascular resistance of the edematous lobe was three times that of nonedematous lobes after indomethacin (149.6 +/- 76% vs. 58.0 +/- 43%). Indomethacin, therefore, decreases shunt possibly by enhancing alveolar hypoxic vasoconstriction and does not block the improvement in shunt with PEEP.

Decreasing hydrostatic pressure does not uniformly decrease high-pressure pulmonary edema

Pulmonary artery wedge pressure (PAWP) of 30 mm Hg with left atrial balloon inflation for 1 1/2 hours produced pulmonary edema in eight dogs. PAWP was then decreased to 10 mm Hg for two hours, and shunt, lung water (extravascular thermal volume, or ETV, by thermal dye), and perfusion distribution (radiomicrosphere technique) were measured and compared with four other dogs (group 1) whose PAWP was maintained at 10 mm Hg. The eight dogs with PAWP of 30 mm Hg for 1 1/2 hours were retrospectively subdivided into two groups of four based on ETV (group 2, double baseline ETV; group 3, triple baseline ETV). Baseline ETV and shunt were similar for all groups and remained unchanged for group 1. At 1 1/2 hours, 2 hours (1/2 hour after decreasing PAWP), 2 1/2 hours, and 3 1/2 hours, respectively, ETV were: 13.9 +/- 1.9, 12.8 +/- 2.0, 9.3 +/- 1.5, and 8.5 +/- 1.0 ml/kg in group 2; and 21.9 +/- 2.1, 22.7 +/- 2.2, 22.5 +/- 2.0, and 22.2 +/- 2.0 ml/kg in group 3. A more variable rate of edema formation was detected in eight additional dogs, but failure to resolve higher levels of edema after decreasing PAWP was also demonstrated in this group. Edema was greatest in lower lobes and decreased lobar perfusion. Shunt was higher in group 3 than in group 2 at 1 1/2 hours and decreased in group 2 but not in group 3 at 3 1/2 hours. Changes in colloid osmotic pressure may account for the differences in edema formation and resolution, but our data suggest that, independent of the rate of edema formation, a decrease in vascular exchange surface area at higher levels of edema may inhibit edema resolution when PAWP is decreased.

Effect of bumetanide in capillary permeability pulmonary oedema

To determine if bumetanide, like furosemide, improves shunt through pulmonary vasoactivity, 20 dogs with unilobar oleic acid pulmonary oedema were studied. Fractional perfusion and intrapulmonary shunt of the oedematous lobe were measured at: baseline, 1 1/2 hours after oleic acid infusion, 15 minutes later after either 0.1 mg X kg-1 of bumetanide in ten dogs (Bumetanide Group) or without bumetanide in ten dogs (Control Group), and 2 1/2 hours after the oleic acid, the bumetanide being administered immediately after the 1 1/2 hours post-oleic acid measurements. Lobar shunts for the Bumetanide Group were: 9.3 +/- 4.0, 54.3 +/- 13.6, 54.7 +/- 13.6, 38.6 +/- 12.0 per cent and for

CONTROLS

8.7 +/- 1.6, 45.1 +/- 8.8, 48.3 +/- 7.8, 70.4 +/- 6.2 per cent. Fractional perfusions of the oedematous lobe were: 29.9 +/- 1, 14.7 +/- 1.1, 14.6 +/- 0.7, 19.3 +/- 1.9 per cent in the Bumetanide Group and 28.6 +/- 2.1, 14.2 +/- 1.1, 14.2 +/- 1.5, and 9.9 +/- 1.1 per cent in CONTROLS. Oedema (wet to body weight ratio) was less (p less than 0.05) in the contralateral lobe (2.5 +/- 0.2 vs. 2.9 +/- 0.3) and the oedematous lobe (4.7 +/- 0.4 vs 6.0 +/- 0.5) after bumetanide-induced diuresis. We conclude that bumetanide decreases shunt by decreasing oedema and not through pulmonary vasoactivity.