Electrical impedance tomography (EIT) for quantification of pulmonary edema in acute lung injury.

BACKGROUND: Assessment of pulmonary edema is a key factor in monitoring and guidance of therapy in critically ill patients. To date, methods available at the bedside for estimating the physiologic correlate of pulmonary edema, extravascular lung water, often are unreliable or require invasive measurements. The aim of the present study was to develop a novel approach to reliably assess extravascular lung water by making use of the functional imaging capabilities of electrical impedance tomography. METHODS: Thirty domestic pigs were anesthetized and randomized to three different groups. Group 1 was a sham group with no lung injury. Group 2 had acute lung injury induced by saline lavage. Group 3 had vascular lung injury induced by intravenous injection of oleic acid. A novel, noninvasive technique using changes in thoracic electrical impedance with lateral body rotation was used to measure a new metric, the lung water ratioEIT, which reflects total extravascular lung water. The lung water ratioEIT was compared with postmortem gravimetric lung water analysis and transcardiopulmonary thermodilution measurements. RESULTS: A significant correlation was found between extravascular lung water as measured by postmortem gravimetric analysis and electrical impedance tomography (r = 0.80; p < 0.05). Significant changes after lung injury were found in groups 2 and 3 in extravascular lung water derived from transcardiopulmonary thermodilution as well as in measurements derived by lung water ratioEIT. CONCLUSIONS: Extravascular lung water could be determined noninvasively by assessing characteristic changes observed on electrical impedance tomograms during lateral body rotation. The novel lung water ratioEIT holds promise to become a noninvasive bedside measure of pulmonary edema.

Extravascular lung water predicts progression to acute lung injury in patients with increased risk*.

OBJECTIVES: To compare the extravascular lung water index and other markers of disease severity in patients with acute lung injury vs. patients at risk for development of acute lung injury and to determine their ability to predict progression to acute lung injury in patients at risk. DESIGN: Extravascular lung water index, dead space fraction, PaO2/FIO2, and other markers of disease severity were measured prospectively in 29 patients daily for 5 days after admission to the intensive care unit. Patients had acute lung injury as defined by the American European Consensus Committee criteria or had risk factors for development of it. SETTING: The intensive care units of an academic tertiary referral hospital. MEASUREMENTS AND MAIN RESULTS: The mean extravascular lung water index on day 1 for patients who progressed to acute lung injury was higher than for those who did not (15.5 ± 7.4 mL/kg vs. 8.7 ± 2.3 mL/kg; p = .04). None of the other physiologic parameters tested discriminated progression to acute lung injury to include the mean physiologic dead space (0.61 ± 0.06] vs. 0.59 ± 0.10; p = .67), PaO2/FIO2 ratio (322 ± 35 vs. 267 ± 98; p = .15), and static lung compliance (30.9 ± 13.5 vs. 38.5 ± 11.7; p = .24). An extravascular lung water index cutoff value on day 1 of 10 mL/kg had a 63% sensitivity, 88% specificity, positive predictive value of 83%, and negative predictive value of 70% to predict progression to acute lung injury. There was no difference in extravascular lung water index between those who progressed to acute lung injury vs. those who had acute lung injury (14.3 ± 4.7 vs. 15.5 ± 7.4; p = .97). CONCLUSIONS: Elevated extravascular lung water index is a feature of early acute lung injury and discriminates between those with acute lung injury and those without. Furthermore, extravascular lung water index predicts progression to acute lung injury in patients with risk factors for development of acute lung injury 2.6 ± 0.3 days before the patients meet American European Consensus Committee criteria for it. These 2.6 ± 0.3 days may then represent missed opportunity for therapeutic intervention and improved outcome.

Identification of barriers to medication adherence in a Latino population.

BACKGROUND: Barriers to medication adherence may present differently in diverse patient populations. Because of changing U.S. demographics, health care providers will be required to identify alternative strategies for managing increasingly diverse patient populations. OBJECTIVES: This pilot project identified barriers that may hinder medication adherence in a Latino population. The results of the survey may identify trends in barriers allowing for the development of interventions aimed at improving medication adherence. METHODS: The study used a convenience sample of Spanish-labeled prescriptions that had not been picked up from a community pharmacy after a 2-week period to identify study subjects. Patients were contacted by phone and surveyed regarding reasons for not picking up their prescription medication. The 24-item survey instrument consisted of demographic and medication-related questions, reasons for, and associated barriers with failure to pick up medications. RESULTS: The most common classes of medications patients failed to pick up were chronic medications. More than 90% of the patients thought that the medication in question was helpful to them, and nearly 80% thought that the medicine was still needed. Patients cited communication issues (ie, content matter, such as when the prescription was ready), logistics, and limited hours of pharmacy operation as the primary barriers in picking up their medications, whereas nearly 40% failed to identify any barriers. Barriers identified by patients that could be improved included confusion regarding when their prescription was ready and limited hours of pharmacy operation. Most of the patients were comfortable using the American health care system. CONCLUSIONS: The barriers to medication adherence identified did not appear to be the result of cultural influences. This could be because the community pharmacy had bilingual staff and interpreters available for patient education and prescription processing. Alternative methods are needed to further identify reasons for failure to pick up medications before medication adherence programs can be designed.

Pulmonary artery catheters in acute heart failure: end of an era?

Whereas the pulmonary artery catheter (PAC) is still widely used in guiding assessment and treatment of heart failure, controversy surrounding its safety and efficacy has prompted development of newer, less invasive techniques. For these purposes, the transpulmonary thermodilution technique allows assessment of preload, cardiac output, filling volumes, and metrics of contractility without the need to pass a catheter through the right heart. In a previous issue of Critical Care, Ritter and colleagues compare metrics of transpulmonary thermodilution with the PAC in patients with acute heart failure and severe sepsis. The results add to a growing body of evidence that the PAC adds little to information attainable by less invasive methods in many conditions, including acute heart failure. Whether newer devices improve outcome needs to be tested in well-controlled prospective trials.

Resuscitation of haemorrhagic shock with normal saline vs. lactated Ringer's: effects on oxygenation, extravascular lung water and haemodynamics.

INTRODUCTION: Pulmonary oedema and impairment of oxygenation are reported as common consequences of haemorrhagic shock and resuscitation (HSR). Surprisingly, there is little information in the literature examining differences in crystalloid type during the early phase of HSR regarding the development of pulmonary oedema, the impact on oxygenation and the haemodynamic response. These experiments were designed to determine if differences exist because of crystalloid fluid type in the development of oedema, the impact on oxygenation and the haemodynamic response to fluid administration in early HSR. METHODS: Twenty anaesthetised swine underwent a grade V liver injury and bled without resuscitation for 30 minutes. The animals were randomised to receive, in a blinded fashion, either normal saline (NS; n = 10) or lactated Ringer's solution (LR; n = 10). They were then resuscitated with study fluid to, and maintained at, the preinjury mean arterial pressure (MAP) for 90 minutes. RESULTS: Extravascular lung water index (EVLWI) began to increase immediately with resuscitation with both fluid types, increasing earlier and to a greater degree with NS. A 1 ml/kg increase in EVLWI from baseline occurred after administartion of (mean +/- standard error of the mean) 68.6 +/- 5.2 ml/kg of normal saline and 81.3 +/- 8.7 ml/kg of LR (P = 0.027). After 150 ml/kg of fluid, EVLWI increased from 9.5 +/- 0.3 ml/kg to 11.4 +/- 0.3 ml/kg NS and from 9.3 +/- 0.2 ml/kg to 10.8 +/- 0.3 ml/kg LR (P = 0.035). Despite this, oxygenation was not significantly impacted (Delta partial pressure of arterial oxygen (PaO2)/fraction of inspired oxygen (FiO2)

Complexity analysis of arterial pressure during periods of abrupt hemodynamic changes.

In this communication, we estimated the Lempel-Ziv complexity (LZC) on over 40 h of arterial blood pressure (ABP) recordings corresponding to 18 mechanically ventilated animal subjects. In this study, all subjects underwent a period of abrupt hemodynamic changes after an induced injury involving severe blood loss leading to hemorrhagic shock, followed by fluid resuscitation using either lactated ringers or 0.9% normal saline. The LZC metric experienced a statistically significant increase (p < 0.01) immediately following the induced injury and a statistically significant reduction following the administration of fluid therapy (p < 0.01). These results indicate that LZC of ABP may be useful as a dynamic metric to assess fluid responsiveness.

Extravascular lung water in sepsis-associated acute respiratory distress syndrome: indexing with predicted body weight improves correlation with severity of illness and survival.

OBJECTIVES: To determine whether extravascular lung water predicts survival in patients with early acute respiratory distress syndrome, to determine the relationship between extravascular lung water and other markers of lung injury, and to examine if indexing extravascular lung water with predicted body weight (EVLWp) strengthens its discriminative power. DESIGN: Extravascular lung water and other markers of lung injury were measured prospectively in 19 patients with sepsis-induced acute respiratory distress syndrome for 3 days. SETTING: The intensive care units of an academic tertiary referral hospital. MEASUREMENTS AND MAIN RESULTS: Lung injury score, Sequential Organ Failure Assessment score, dead space-tidal volume fraction (Vd/Vt), and EVLWp were all significantly higher on day 1 in nonsurvivors compared with survivors (lung injury score, 2.8 +/- 0.34 vs. 1.9 +/- 0.50; p = .004) (Sequential Organ Failure Assessment score, 13 +/- 3.4 vs. 7.7 +/- 0.8; p = .006) (Vd/Vt, 0.68 +/- 0.07 vs. 0.58 +/- 0.07; p = .009) (EVLWp, 20.6 +/- 4.6 vs. 11.6 +/- 1.9 mL/kg; p = .002). EVLWp correlated with Sequential Organ Failure Assessment score, lung injury score, Vd/Vt, and PaO2/FIO2. The receiver operator characteristic curve analysis indicated that EVLWp, Vd/Vt, and extravascular lung water (p = .0005, .009, and .013, respectively) but not PaO2/FIO2 (p = .311) discriminate between survivors and nonsurvivors. Three-day average EVLWp >16 mL/kg predicted in-hospital mortality with 100% specificity and 86% sensitivity. CONCLUSIONS: Increased extravascular lung water is a feature of early acute respiratory distress syndrome and predicts survival. Indexing extravascular lung water to predicted body weight, instead of actual body weight, improves the predictive value of extravascular lung water for survival and correlation with markers of disease severity.

Liver lesions in demersal fishes near a large ocean outfall on the San Pedro Shelf, California.

The prevalence of toxicopathic liver lesions in demersal fish on the San Pedro Shelf, California was determined for a 15-year period (1988-2003). Fish livers were sampled at fixed locations as part of the Orange County Sanitation Districts (OCSD) ocean monitoring program. Histopathological examination of selected fish liver tissues was studied to determine whether the wastewater discharge had affected fish health. The prevalence of toxicopathic lesion classes neoplasms (NEO), preneoplastic foci of cellular alteration (FCA), and hydropic vacuolation (HYDVAC) varied among species and locations. For all species sampled, severe lesions occurred in 6.2% of the fish examined (n=7,694). HYDVAC (4.1%) was the most common toxicopathic lesion type followed by FCA (1.4%) and NEO (0.7%). HYDVAC occurred only in white croaker (Genyonemus lineatus), accounting for 84.8% of the toxicopathic lesions for this species. Prevalence of HYDVAC, NEO, and FCA in white croaker was 15.2, 2.0, and 0.7%, respectively. The prevalence of HYDVAC and NEO in white croaker increased with age and size but there was no sexual difference. A linear regression model was used for hypothesis testing to account for significant differences in fish size (and age for croakers) at the different sampling locations. This analysis showed that for HYDVAC there was no spatial or location effect for lesion rate or size/age of onset. For NEO, the model predicted that white croaker near the wastewater outfall may acquire these lesions at a smaller size/younger age, and at a higher rate, than at other sites. However, this result may be biased due to the unequal size frequency distributions and the low prevalence of NEO in white croaker at the different sampling sites. Bigmouth sole (Hippoglossina stomata) had a prevalence of FCA and NEO of 1.3 and 0.35%, respectively, but the prevalence and distribution of lesions was too few for statistical testing. There was no sexual difference for lesion prevalence in hornyhead turbot (Pleuronichthys verticalis) and the prevalence of FCA and NEO was 3.4 and 0.37%, respectively. FCA prevalence increased with size in hornyhead turbot and there were no significant spatial differences for lesion rates and fish size at lesion onset. Overall, consistent spatial differences for lesion prevalence were not demonstrated and highlight the analytical difficulties of detecting a possible point source impact when the effect is rare, correlated with the size/age structure of the population, and may be caused by exposure to unknown multiple sources. Thus, the usefulness of liver histopathology as a point-source monitoring tool is best applied to where the spatial scale of impact generally exceeds the home range of the target species.

Contaminant exposures at the 4H shell mounds in the Santa Barbara Channel.

Remobilization, bioavailability, and potential toxicity of chemical contaminants were evaluated at the 4H shell mounds - the site of abandoned offshore oil and gas production platforms in the Santa Barbara Channel region of the Southern California Bight. Evaluations used a weight-of-evidence approach based on results from bulk phase chemical analyses and laboratory toxicity testing of shell mound cores, in situ field bioassays using caged mussels, and surficial sediment chemistry. Shell mound cores contained elevated concentrations of metals associated with drilling wastes (e.g., Ba, Cr, Pb, and Zn), as well as monocyclic and polycyclic aromatic hydrocarbons (PAHs). The highest concentrations along with pockets of free oil were associated with the middle "cuttings" stratum. Sediments composited from all core strata caused significant acute toxicity and bioaccumulation of Ba and PAHs in test organisms during laboratory exposures. In contrast, caged mussels placed at each of the shell mounds for a period of 57-58 days had greater than 90% survival, and there were no significant differences in survival of mussels placed at the shell mounds and corresponding reference sites. While all mussel samples exhibited increases in shell length, whole animal weight, and tissue lipid content, in some cases growth metrics for the shell mound mussels were significantly higher than those for the reference sites. Concentrations of metals, PAHs, and polychlorinated biphenyls (PCBs) in tissues of the shell mound mussels were not significantly different from those at reference sites. The presence of labile aromatic hydrocarbons in shell mound cores and absence of significant contaminant accumulation of tissues of caged mussels indicated that chemical contaminants are not being remobilized from the 4H shell mounds. Surficial bottom sediments near the shell mounds contained elevated Ba concentrations that probably were associated with drilling wastes. However, concentrations did not exhibit clear spatial gradients with distance from the shell mounds. Despite a number of storm events during the mussel exposures, maximum currents were 34 cm s(-1) and unlikely to erode materials from the shell mounds. Thus, Ba distributions in bottom sediments probably were due to episodic disturbance such as platform removal or trawling rather than ongoing erosion and dispersion of shell mound solids by near-bottom currents. These results suggest that, in the absence of physical disturbances, contaminants are expected to remain sequestered in the shell mounds.

A novel algorithm to estimate the pulse pressure variation index deltaPP.

We designed a new methodology to estimate the pulse pressure variation index (deltaPP) in arterial blood pressure (ABP). The method uses automatic detection algorithms, kernel smoothing, and rank-order filters to continuously estimate deltaPP. The technique can be used to estimate deltaPP from ABP alone, eliminating the need for simultaneously acquiring airway pressure.

Implementation and evaluation of a lipid screening program in a large chain pharmacy.

OBJECTIVE: To evaluate the implementation of a lipid testing service across an entire market of a large chain pharmacy. DESIGN: Observational study using a validated satisfaction scale. SETTING: Nine Osco Drug pharmacies in Des Moines, Iowa. MAIN OUTCOME MEASURES: Number of patients choosing to participate in a fee-for-service lipid screening program, type of test chosen, effects of marketing on service volume, and patient satisfaction. RESULTS: A total of 159 screenings were performed in the 9 pharmacies. The majority of patients (79.7%) chose the more expensive fasting lipid profile, and service volume seemed to correspond to the number and intensity of marketing efforts. There was a trend toward increased patient satisfaction with the services represented by the Managing Therapy and Friendly Explanation dimensions addressed in the survey. CONCLUSION: Patients were willing to pay out-of-pocket for lipid screening. More efforts need to be devoted to marketing this service to create value for the customer and to establish it as a viable component of pharmacy business.