Catamenial pneumothorax and other thoracic manifestations of endometriosis

Thoracic endometriosis syndrome is an uncommon entity with varied clinical manifestations. Its pathogenesis is not understood completely. Recurrent unilateral right-sided pneumothorax that occurs within days of the onset of menstruation is the most common presentation. Clinical suspicion and recognition of the temporal relationship of the patient's symptoms with menses are essential to establish the diagnosis. Radiographic studies, bronchoscopy, and thoracoscopy may support the diagnosis. Pathologic evidence of thoracic endometrial tissue is not present universally. Therapeutic interventions, which include medical and surgical options, must be individualized for each patient.

Activity of faropenem and imipenem for ciprofloxacin-resistant bacteria

AIM

To determine whether an association exists between ciprofloxacin and faropenem resistance in bacteria including multiply drug-resistant isolates.

METHODS

The MICs were determined for 150 fluoroquinolone-resistant bacteria, plus 20 nalidixic acid-resistant strains of Salmonella enterica serovar Typhimurium.

RESULTS

Faropenem was very active against Escherichia coli and Streptococcus pneumoniae, but 5/31 Staphylococcus aureus and 2/26 Bacteroides fragilis required > or =16 mg/L for inhibition. Of 30 multiply drug-resistant isolates with a phenotype suggestive of enhanced efflux, only for one strain (a Bacteroides fragilis) was the faropenem MIC higher than that associated with the other isolates of the same species.

CONCLUSIONS

Faropenem was in general as active as imipenem. There was no association between resistance to ciprofloxacin and faropenem or imipenem resistance.

Clinical relevance of time of onset, duration, and type of pulmonary edema after liver transplantation

We investigated the clinical significance of time of onset, duration, and type of pulmonary edema after orthotopic liver transplantation by retrospectively reviewing 93 consecutive recipients. Pulmonary edema was diagnosed by means of radiographic criteria and Pao(2)/Fio(2) ratio <300. Type was identified by pulmonary artery wedge pressure (hydrostatic, >18 mm Hg; permeability, < or =18 mm Hg). Of 91 evaluable patients, 44 (48%) had no pulmonary edema, 23 (25%) had immediate pulmonary edema resolving within 24 hours, 8 (9%) had late pulmonary edema (developing de novo in the first 16 to 24 hours), and 16 (18%) had persistent pulmonary edema (developing immediately and persisting for at least 16 hours). At 16 to 24 hours, mean arterial pressure was lower with persistent permeability-type edema than without pulmonary edema (75 versus 87 mm Hg, P <.01). Patients with persistent permeability-type edema had higher mean pulmonary arterial pressure (23 versus 16 mm Hg, P <.01) and higher pulmonary vascular resistance (103 versus 53 dyn. second. m(-5), P <.05), consistent with a resistance-dependent mechanism. Patients with persistent hydrostatic-type edema did not differ from those without edema in mean arterial pressure (84 versus 87 mm Hg, P >.05) or pulmonary vascular resistance (67 versus 53 dyn. second. m(-5), P >.05), but had increased mean pulmonary arterial pressure (27 versus 16, P <.01), suggesting a flow volume-dependent mechanism. Duration of mechanical ventilation, intensive care, and hospital stay were prolonged in patients with late or persistent permeability-type edema but not in patients with immediate pulmonary edema of any type. In conclusion, immediate pulmonary edema resolving within 24 hours after liver transplantation had little clinical consequence; persistent permeability-type pulmonary edema portended a worse outcome.

Accumulation of 10 fluoroquinolones by wild-type or efflux mutant Streptococcus pneumoniae

A method for measuring fluoroquinolone accumulation by Streptococcus pneumoniae was rigorously examined. The accumulation of ciprofloxacin, clinafloxacin, gatifloxacin, grepafloxacin, levofloxacin, moxifloxacin, norfloxacin, ofloxacin, sitafloxacin, and trovafloxacin in the presence and absence of either carbonyl cyanide m-chlorophenyl-hydrazone (CCCP) or reserpine was determined for two wild-type fluoroquinolone-susceptible capsulated S. pneumoniae strains (M3 and M4) and the noncapsulated strain R6. Two efflux mutants, R6N (which overexpresses PmrA) and a mutant of M4, M22 (no expression of PmrA), were also examined. Essentially, the fluoroquinolones fell into two groups. (i) One group consisting of ciprofloxacin, grepafloxacin, and norfloxacin accumulated to 72 to 92 ng/mg (dry weight) of cells in all strains. (ii) The remainder of the agents accumulated to 3 to 30 ng/mg (dry weight) of cells. With a decrease in hydrophobicity, there was a decrease in the concentration accumulated. With an increase in the molecular weight of the free form of each agent, there was also a decrease in the concentration accumulated. The strains differed in their responses to reserpine and CCCP. For the three fluoroquinolone-susceptible strains, only reserpine had a significant effect upon accumulation of moxifloxacin and clinafloxacin by M3 and showed no effect for the other agents and strains. For M3 and M4, CCCP enhanced the concentration of ciprofloxacin and norfloxacin accumulated, whereas for R6, the effect was only statistically significant for ofloxacin. Efflux mutant M22 accumulated less ciprofloxacin, gatifloxacin, and ofloxacin than M4 did. M22 accumulated more norfloxacin than M4 did. Reserpine and CCCP had variable effects as for the other strains. Differences in the accumulation of fluoroquinolones by R6 and R6N were highly dependent upon growth phase, and only for norfloxacin was there a significant difference between two strains.

An optimized system for studies of EPO-dependent murine pro-erythroblast development

OBJECTIVE

Objectives were to develop new means to isolate useful numbers of primary progenitor cells and to quantitatively assay the stepwise maturation of erythroblasts.

METHODS

Approaches involved dosing mice with thiamphenicol (TAP) to yield staged cohorts of pro-erythroid cells; optimizing conditions for their EPO-dependent in vitro growth and survival; developing assays for CFU-E maturation; analyzing stage-specific transcript expression; and expressing a heterologous, erythroid-specific tag (EE372) in transgenic mice.

RESULTS

Per TAP-treated mouse, 3 x 10(7) highly EPO-responsive erythroid progenitor cells were generated that represented up to 30% of total splenocytes and showed strict dependence on EPO for survival, growth, and immediate response gene expression. In this developing cohort, a tightly programmed sequence of gene expression was observed, and maximal expression of c-kit, EPO receptor, and beta-globin transcripts occurred at 72, 96, and 120 hours post-TAP withdrawal, respectively. Also, the newly discovered erythroid-specific dual-specificity kinase, DYRK3, was revealed to be expressed at a late CFU-E stage. In vitro, these progenitor cells matured stepwise from high FALS Ter119- cells (24-hour culture) to high FALS Ter119+ cells (24-36 hours) to low FALS Ter119+ maturing erythroblasts (40-48 hours) and sharp differences in their morphologies were observed. Finally, a MACS-based procedure for the purification of erythroid progenitor cells from TAP-treated EE372 transgenic mice also was developed.

CONCLUSIONS

A comprehensive new system for isolating large numbers of primary murine erythroid progenitor cells and quantitatively monitoring their development is established that should serve well in investigations of endogenous and pharmacological regulators of red blood cell development.

Urban-rural differences in a memory disorders clinical population

OBJECTIVES

To compare patient characteristics and family perceptions of patient function at one urban and one rural memory disorders clinic.

DESIGN

Secondary, cross-sectional data analyses of an extant clinical database.

SETTING/PARTICIPANTS

First time visits (n = 956) at two memory disorders clinics.

MEASUREMENTS

Patient and family-member demographics and assessment results for the Mini-Mental State Examination (MMSE), instrumental activities of daily living (IADLs), activities of daily living (ADLs), the Memory Change and Personality Change components of the Blessed Dementia Rating Scale, and the Revised Memory and Behavior Problems Checklist.

RESULTS

In both clinics, patients and family members were more likely female. The typical urban clinic patient was significantly more likely to be living in a facility and more educated than the typical rural patient. Urban and rural patients did not show significant differences in age- and education-adjusted MMSE scores or raw ADL/IADL ratings, but the urban family members reported more memory problems, twice as many personality changes, more-frequent behavior problems, and more adverse reactions to problems.

CONCLUSION

Physicians who practice in both urban and rural areas can anticipate differences between patients, and their families, who seek a diagnosis of memory disorders. Our most important finding is that despite similarities in reported functional abilities, urban families appear to be more sensitive to and more distressed by patients' cognitive and behavioral symptoms than rural families. These differences may reflect different underlying needs, and should be explored in further research.

Effective antigen-specific immunotherapy in the marmoset model of multiple sclerosis

Mature T cells initially respond to Ag by activation and expansion, but high and repeated doses of Ag cause programmed cell death and can suppress T cell-mediated diseases in rodents. We evaluated repeated systemic Ag administration in a marmoset model of experimental allergic encephalomyelitis that closely resembles the human disease multiple sclerosis. We found that treatment with MP4, a chimeric, recombinant polypeptide containing human myelin basic protein and human proteolipid protein epitopes, prevented clinical symptoms and did not exacerbate disease. CNS lesions were also reduced as assessed in vivo by magnetic resonance imaging. Thus, specific Ag-directed therapy can be effective and nontoxic in primates.

Diversity in medical school: perceptions of first-year students at four southeastern U.S. medical schools

PURPOSE

To assess students' perceptions of the extent of diversity in their classes, the role of diversity in their first-year curriculum, and their predictions of the amount of diversity in their future patient populations.

METHOD

In 1998, students at four southeastern U.S. medical schools that had distinct demographics and differing institutional missions completed a questionnaire on diversity at the end of the first year. In the instrument, diversity was defined according to nine population characteristics: age, sex, race, ethnic background, physical disability, religious affiliation, sexual orientation, socioeconomic status, and rural background (growing up in a community of less than 5,000). Responses were compared according to students' institution, sex, and race.

RESULTS

Questionnaires were returned by 349 of 474 students (74%). Students at the school with the most diverse first-year class placed the greatest value on the contributions of diversity to the learning environment. Women students placed more value on the inclusion of diversity issues in the curriculum than did men students, and they placed greater value on understanding diversity issues in their future medical practices than did men. Compared with Asian American, Hispanic, and white students, African American students were the least likely to think that the curriculum contained adequate information about diversity.

CONCLUSIONS

The results indicate that perceptions of diversity were influenced by the students' own demographic characteristics and those of their medical school. The more diverse the class, the more comfortable the students were with diversity and the more they valued its contribution to their medical education.

Physicians and clergy as facilitators of formal services for older adults

Researchers have sought to understand the determinants of the use of in-home and community-based services in order to better serve the needs of older adults. One component frequently included in formal service utilization models is the role of individuals who exert an influence on the service use process. An analysis of in-depth interviews conducted with 115 older adults revealed the important facilitating role that physicians and religious leaders play in encouraging the use of these services. The sample, which included African-American and white adults age 65+ from rural and urban environments, described various ways in which these "facilitators" influence the use of formal services. These ways include: (1) supplying instrumental support either by "ordering" a particular program for or linking the elder with the program and (2) providing informational and affective support, including advising or recommending the use of a program, conveying necessary background on formal services, and legitimizing the use of formal services. Regardless of personal characteristics (such as ethnicity and residence), a majority of elders in the sample recognized the important role played by physicians, and clergy. The acknowledgement of the role played by these facilitators should be viewed as an opportunity for physicians and clergy to enhance the knowledge and appropriate use of needed formal services for elders. In addition, these findings have policy implications for the current provision of aging services.

Artifacts and the visualization of fetal distal extremities using three-dimensional ultrasound

OBJECTIVES

To demonstrate that acoustic shadowing in 3D US may give rise to artifacts simulating limb defects and provide a solution to eliminate its occurrence.

METHODS

Twenty second trimester fetuses (gestational age 15-24 weeks) were scanned with three-dimensional ultrasound (3D US) using a sagittal acquisition plane. Fetal tibia/fibula and radius/ulna pairs were assessed for completeness of imaging. A further 20 fetuses (gestational age 20-26 weeks) were scanned in both axial and sagittal planes and the results compared to verify clear visualization of both bones.

RESULTS

Shadowing from adjacent structures produced an apparent limb defect in 55% of the first 20 fetuses imaged only sagittally (18% of limb pairs). Acquiring data from more than one orientation avoided this artifact.

CONCLUSIONS

The 3D US is subject to the same artifacts as two-dimensional (2D US) in terms of acoustic shadowing, although their presentation may be different. Awareness of this fact is essential for correct interpretation of 3D US studies. Three-dimensional scanning protocols should be modified to ensure that fetal structures are adequately visualized by acquiring volume data in more than one acquisition orientation.

Effect of external dead volume on performance while wearing a respirator

Respirator dead volume accumulates exhaled carbon dioxide and returns it to the respiratory system during subsequent inhalations. Because inhaled carbon dioxide is known to be a powerful respiratory stimulant and psychoactive gas, respirator dead volume would be expected to influence performance times while respirators are worn during work. This experiment was performed at intense levels of treadmill walking (80-85% VO2max) to demonstrate maximum sensitivity to respiratory stress. Six dead volume conditions (representing a range of 280 to 1,160 mL) were imposed on the subjects. Results show linear decreases in performance times and breathing apparatus comfort with increasing dead volumes. For each 350 mL of external dead volume, a 19% decrease of performance time and an 18% decrease in breathing apparatus comfort can be expected.

Addition of eicosapentaenoic acid to gamma-linolenic acid-supplemented diets prevents serum arachidonic acid accumulation in humans

Previous studies reveal that supplementation of human diets with gamma-linolenic acid (GLA) reduces the generation of lipid mediators of inflammation and attenuates clinical symptoms of chronic inflammatory disorders such as rheumatoid arthritis. However, we have shown that supplementation with this same fatty acid also causes a marked increase in serum arachidonate (AA) levels, a potentially harmful side effect. The objective of this study was to design a supplementation strategy that maintained the capacity of GLA to reduce lipid mediators without causing elevations in serum AA levels. Initial in vitro studies utilizing HEP-G2 liver cells revealed that addition of eicosapentaenoic acid (EPA) blocked Delta-5-desaturase activity, the terminal enzymatic step in AA synthesis. To test the in vivo effects of a GLA and EPA combination in humans, adult volunteers consuming controlled diets supplemented these diets with 3.0 g/d of GLA and EPA. This supplementation strategy significantly increased serum levels of EPA, but did not increase AA levels. EPA and the elongation product of GLA, dihomo-gamma-linolenic acid (DGLA) levels in neutrophil glycerolipids increased significantly during the 3-wk supplementation period. Neutrophils isolated from volunteers fed diets supplemented with GLA and EPA released similar quantities of AA, but synthesized significantly lower quantities of leukotrienes compared with their neutrophils before supplementation. This study revealed that a GLA and EPA supplement combination may be utilized to reduce the synthesis of proinflammatory AA metabolites, and importantly, not induce potentially harmful increases in serum AA levels.

Acquired thermotolerance and expression of the HSP100/ClpB genes of lima bean

Acquired thermotolerance (AT) is the ability of cells to survive a normally lethal temperature treatment as a consequence of pretreatment at an elevated but sublethal temperature. In yeast and cyanobacteria, the expression of the HSP100/ClpB protein is required for the AT response. To determine whether the HSP100/ClpB protein is associated with this response in lima bean (Phaseolus lunatus), we have cloned an HSP100/ClpB homolog and assessed expression of the two gene copies under heat stress conditions, which induce AT. Transcription of the cytoplasmically localized HSP100/ClpB protein genes is stringently controlled by heat stress in both of the laboratory and field heat stress conditions. From a heat-induced cDNA library, we identified a clone of a putative chloroplast-targeted (cp) HSP100/ClpB protein gene sequence. The cp HSP100/ClpB protein genes are constitutively expressed, but transcript levels increase post-heat stress in laboratory heat stress experiments. In field conditions the genes for the cp HSP100/ClpB are constitutively expressed. Although we were unable to correlate differences in the timing of AT response with the expression or genetic structure of the HSP100/ClpB genes in heat-tolerant or -sensitive varieties of lima bean, we clearly demonstrate the association of expression of HSP100/ClpB proteins with heat response in this species.

Purchasing over-the-counter medications: the influence of age and familiarity

This study examines the influence of age and type of over-the-counter (OTC) medications on decision-making processes leading to the selection of OTC medications. Manipulating type of OTC medication served as a way of examining subjects' familiarity with the decision domain. Thirty-six younger and thirty-six older adults answered questions regarding their OTC medication purchases, and completed a decision task in which they searched four computerized displays of product label information in order to select an antacid, a cold medication, a laxative, and a pain reliever. In general, older adults were slower to review information, more likely to have used OTC medications, and more organized in their searches for information. Specific to pair relievers, older and younger adults demonstrated similar information use and time to decision, and older adults specifically tailored the organization of their information searches when choosing pain relievers. Clearly, older adults selectively use product information on OTC medication packages, given adequate time to process information. Manufacturers' efforts directed at improving information availability should benefit older adults' decision processes.

Communication using a telephone while wearing a respirator

Respirators have been found to degrade communication effectiveness when wearers speak face-to-face. However, little is known about communication effectiveness when using the telephone and wearing a respirator. Eleven pairs of subjects were asked to pronounce and identify words chosen from Modified Rhyme Test lists. Each word appeared on a computer screen in one room and the speaker said the word into the telephone. The listener in another room identified the word and typed it into a computer linked with the first. Subjects wore U.S. Army M40 full-facepiece air-purifying respirators with hoods. Three different speech diaphragm arrangements and two hood materials were tested. Results show that accuracy suffered by about 10% when respirators and hoods were worn compared with the control condition. Word identification speed was one-third to one-half of the control (no respirator or hood) condition depending on specific equipment worn.

Venous air embolism from central venous catheterization: a need for increased physician awareness

OBJECTIVES

To report a series of patients with clinically diagnosed venous air embolism (VAE) and major sequelae as a complication of the use of central venous catheters (CVCs), to survey health care professionals' practices regarding CVCs, and to implement an educational intervention for optimizing approaches to CVC insertion and removal.

SETTING

Tertiary care, university-based 806-bed medical center.

INTERVENTIONS

We surveyed 140 physicians and 53 critical care nurses to appraise their awareness of the proper management and complications of CVCs. We then designed, delivered, and measured the effects of a multidisciplinary educational intervention given to 106 incoming house officers.

MEASUREMENTS AND MAIN RESULTS

Although most physicians (127, 91%) chose the Trendelenburg position for CVC insertion, only 42 physicians (30%) reported concern for VAE. On CVC removal, only 36 physicians (26%) cited concern for VAE. Some physicians (13, 9%) reported elevating the head of the bed during CVC removal, possibly increasing the risk of VAE. Awareness of VAE or its prevention did not correlate with the level of physician training, experience, or specialty. After the educational intervention, concern for and awareness of proper methods of prevention of VAE improved (p < .001). At 6-month follow-up, reported use of the Trendelenburg position continued, but concern cited for VAE had returned to baseline.

CONCLUSIONS

There is inadequate awareness of VAE as a complication of CVC use. Focused instruction can improve appreciation of this potentially fatal complication and knowledge of its prevention, but the effect declines rapidly. To achieve a more sustained improvement, a more intensive, hands-on, periodic educational program will likely be necessary, as well as reinforcement through enhanced supervision of CVC insertion and removal practices.

Role of arachidonyl triglycerides within lipid bodies in eicosanoid formation by human polymorphonuclear cells

Increasing evidence suggests that the subcellular and glycerolipid localization of esterified arachidonic acid (AA) is a key factor in regulating its availability to lipases. The goal of the current study was to determine the potential of AA stored in triglycerides (TG) to serve as a substrate for lipases and 5-lipoxygenase during neutrophil (polymorphonuclear leukocytes, PMN) activation. PMN containing high concentrations of AA in TG were generated by culturing PMN in vitro with high concentrations of exogenous AA (eAA) for 12 h. Cellular AA increased 2- and 4-fold in PMNs incubated with 5 and 20 microM AA, respectively, and this increase was almost exclusively observed in neutral lipids (NL). Further analysis revealed that 88% of the AA in the NL fraction was associated with TG. Subsequent experiments were designed to determine whether this AA in TG could be mobilized and metabolized to eicosanoids during cell activation. TG pools of AA were increased as previously described and then PMN were stimulated with ionophore, A23187. In contrast to the 43-fold increase in TG AA after eAA loading (20 microM), free AA increased by only 1.9-fold after cell stimulation. Similarly, leukotriene (LT)B(4) production increased only 2-fold after loading TG with large quantities of AA. The magnitude of increase in free AA released and in LTB(4) formation was similar to the magnitude of increase in AA mass in phospholipase (PL), suggesting that PL, and not TG, served as the source of released AA and subsequent product generation. To confirm that AA in TG did not serve as a source for eicosanoid production, cellular pools of AA were differentially labeled with [(14)C]AA and [(3)H]AA, and the [(3)H]AA-to-[(14)C]AA ratio of LTB(4) and 20-hydroxyl LTB(4) produced during cell stimulation was measured. The [(3)H]AA/[(14)C]AA ratios of LTs were markedly different from the ratios in TG, thus providing further evidence that AA pools in TG are not a major source of AA for LT generation.

Effect of carbon dioxide on testing of susceptibilities of respiratory tract pathogens to macrolide and azalide antimicrobial agents

The in vitro activities of erythromycin, azithromycin, and clarithromycin against 178 clinical isolates from the lower respiratory tract of patients with chronic obstructive pulmonary disease were determined by an agar dilution method. The plates were incubated in air alone or in 5% carbon dioxide. The MICs measured in air alone were lower for most isolates than those measured in 5% carbon dioxide, illustrating the "pH effect" of incubation in carbon dioxide. Testing of isolates in 5% carbon dioxide on pH-adjusted medium (pH 8.4) resulted in MICs of one or two doubling dilutions lower than those obtained on agar with a neutral pH. A bioassay of the three agents incubated in air and in 5% carbon dioxide resulted in a significant loss of activity of all three agents in the carbon dioxide-enriched atmosphere. However, this loss-of-activity effect was significantly reduced when the bioassay medium was adjusted to pH 8.4 prior to incubation in 5% carbon dioxide.

Effect of respirator inspiratory resistance level on constant load treadmill work performance

Respirator inspiratory resistance can affect performance times, especially when the experiment is optimized to elicit respiratory stress. Twelve subjects performed on a treadmill at constant speeds and grades chosen to result in performance times of 5-15 min. Six levels of inspiratory resistance were used, ranging from 0.78 to 7.64 cm H2O.sec/L. The results showed that performance times decrease linearly with resistance level, and no threshold resistance value is apparent. Inspiratory resistance also induces hypoventilation, with lower minute volumes and lower oxygen consumption values at higher resistances. These trends are also linear. From these results, there is no value for inspiratory resistance that can be given as a design goal. Other parameters such as weight and space may dictate filter resistance values, and these, in turn, will lead to determined performance degradations.

Interactions with colleagues and their effects on the satisfaction of rural primary care physicians

Physician work satisfaction is related to several aspects of practice organization, including work group or colleagues, job content, work hours, and future opportunities. Practice location is an important determinant of practice organization and personal life satisfaction. This study compared the professional satisfaction of physicians in rural and urban settings to determine how practice setting, practice type, work hours, and interactions with colleagues influenced satisfaction. Surveys focusing on professional satisfaction were mailed to community-based, primary care physicians in Kentucky. Overall, physicians were satisfied with their practices, with physicians in larger communities being more satisfied than those from smaller communities. Professional satisfaction was associated with practice location, practice type, number of years since graduation from medical school, number of colleagues identified, and the quality of professional interactions with colleagues. The study concluded that collegial support for physicians is important in creating work environments that promote professional satisfaction.

Determinant spreading associated with demyelination in a nonhuman primate model of multiple sclerosis

Definition of the immune process that causes demyelination in multiple sclerosis is essential to determine the feasibility of Ag-directed immunotherapy. Using the nonhuman primate, Callithrix jacchus jacchus (common marmoset), we show that immunization with myelin basic protein and proteolipid protein determinants results in clinical disease with significant demyelination. Demyelination was associated with spreading to myelin oligodendrocyte glycoprotein (MOG) determinants that generated anti-MOG serum Abs and Ig deposition in central nervous system white matter lesions. These data associate intermolecular "determinant spreading" with clinical autoimmune disease in primates and raise important issues for the pathogenesis and treatment of multiple sclerosis.

Radiographic assessment of hyperinflation: correlation with objective chest radiographic measurements and mechanical ventilator parameters

BACKGROUND

Pulmonary barotrauma is a potentially fatal complication of positive pressure ventilation. We previously found that barotrauma occurred in patients with radiographic hyperinflation, but few objective data define the relationships among hyperinflation, objective chest radiograph (CXR) measurements, ventilator parameters, and development of barotrauma.

OBJECTIVES

We sought (1) to assess the relationships among hyperinflation, objective CXR findings, mechanical ventilator parameters, and development of barotrauma. (2) To compare radiographic hyperinflation, ventilator parameters, and incidence of barotrauma in a current group of ICU patients with historical control subjects.

SETTING

Medical and surgical ICU patients in a university hospital.

DESIGN

Prospective blinded observational study; comparison of current series with historical control subjects.

METHODS

One hundred two prospectively enrolled mechanically ventilated medical and surgical ICU patients each received portable supine CXRs that were reviewed independently by three radiologists who made objective measurements and subjectively determined the likelihood of hyperinflation. Ventilator parameters were recorded at the bedside at the time each CXR was obtained. CXR measurements and ventilator parameters were then related to the development of barotrauma during the course of ventilation and compared with findings of a prospective study at our institution 1 year earlier.

RESULTS

Radiographically recognizable hyperinflation occurred in 18 of 102 mechanically ventilated ICU patients (18%) and correlated with lung length (24.7 vs 19.8 cm; p<0.05) and the anterior rib number that intersects the hemidiaphragm (5.4 vs 4.7; p<0.05). Patients with hyperinflation were ventilated at higher tidal volume per kilogram (VT/kg) (11.0 vs 9.4; p=0.0081), but peak airway pressure, plateau pressure, and positive end-expiratory pressure were similar. There were significant decreases in VT (810 vs 739 mL; p=0.015) and VT/kg (11.0 vs 10.1 mL/kg; p<0.001) in these mechanically ventilated ICU patients in comparison to hospital control subjects evaluated during the previous year. Paralleling these changes was a decrease in the frequency of CXR hyperinflation (p=0.003) and the incidence of ventilator-associated barotrauma (6.5% vs 0.98%; p=0.048).

CONCLUSIONS

Ventilation at higher VT/kg is associated with a higher incidence of CXR hyperinflation. Radiographic hyperinflation is associated with lung length > or =24.7 cm and visualization of the sixth anterior rib. Patients with hyperinflation may be at greater risk for developing barotrauma or volutrauma. Ventilatory strategies utilizing lower volumes are associated with a lower incidence of such trauma in the current sample as compared with historical control subjects.

Dietary supplementation with gamma-linolenic acid alters fatty acid content and eicosanoid production in healthy humans

To understand the in vivo metabolism of dietary gamma-linolenic acid (GLA), we supplemented the diets of 29 volunteers with GLA in doses of 1.5-6.0 g/d. Twenty-four subjects ate controlled eucaloric diets consisting of 25% fat; the remaining subjects maintained their typical Western diets. GLA and dihomo-gamma-linolenic acid (DGLA) increased in serum lipids of subjects supplemented with 3.0 and 6.0 g/d; serum arachidonic acid increased in all subjects. GLA supplementation with 3.0 and 6.0 g/d also resulted in an enrichment of DGLA in neutrophil phospholipids but no change in GLA or AA levels. Before supplementation, DGLA was associated primarily with phosphatidylethanolamine (PE) of neutrophil glycerolipids, and DGLA increased significantly in PE and neutral lipids after GLA supplementation. Extending the supplementation to 12 wk did not consistently change the magnitude of increase in either serum or neutrophil lipids in subjects receiving 3.0 g/d. After GLA supplementation, A23187-stimulated neutrophils released significantly more DGLA, but AA release did not change. Neutrophils obtained from subjects after 3 wk of supplementation with 3.0 g/d GLA synthesized less leukotriene B4 (P < 0.05) and platelet-activating factor. Together, these data reveal that DGLA, the elongase product of GLA, but not AA accumulates in neutrophil glycerolipids after GLA supplementation. The increase in DGLA relative to AA within inflammatory cells such as the neutrophil may attenuate the biosynthesis of AA metabolites and may represent a mechanism by which dietary GLA exerts an anti-inflammatory effect.