The use of nonphysician providers in adult intensive care units.

In the United States there are not currently enough critical care-trained practitioners to provide care to all critically ill patients. With calls for "high-intensity" staffing and 24-hour coverage of our intensive care units, the board-certified intensivists we do have are being stretched ever more thin. Nonphysician providers (physician assistants and nurse practitioners) are being used with increasing frequency in critical care settings to provide care to critically ill patients. In this review, we explore the impact of introducing nonphysician providers into the adult intensive care unit.

Polycyclic aromatic hydrocarbons impair function of ß2-adrenergic receptors in airway epithelial and smooth muscle cells.

Incomplete combustion produces a pollutant mixture that includes polycyclic aromatic hydrocarbons (PAHs). Previous work by the Columbia Center for Children's Environmental Health (CCCEH) and others linked exposure to PAH with symptoms of asthma and other adverse health effects in young children. Inhaled ß(2)-adrenergic agonists are mainstays in the treatment of reactive airway diseases. These exogenous catecholamines engage membrane-bound ß(2)-adrenergic receptors (ß(2)AR) on airway epithelial and smooth muscle cells to cause airway dilation. We hypothesized that exposure to PAH might similarly interfere with the function of ß(2)AR in airway epithelial or smooth muscle cells, reducing the efficacy of a medication important for the treatment of asthma symptoms. A PAH mixture was devised, based on ambient levels measured prenatally among a cohort of pregnant women participating at the CCCEH. Primary airway epithelial and smooth muscle cells were exposed to varying concentrations of the PAH mixture, and expression, function, and signaling of ß(2)AR were assessed. Murine tracheal epithelial cells and human airway smooth muscle cells, after exposure to a PAH mixture, exhibited reduced expression and function of ß(2)AR. These findings support our hypothesis that environmentally relevant PAHs can impede ß(2)AR-mediated airway relaxation, and suggest a new paradigm where air pollutants not only contribute to the pathogenesis of childhood asthma, but also diminish responsiveness to standard therapy.

Vascular inflammation in obesity and sleep apnea.

BACKGROUND: Unrecognized obstructive sleep apnea (OSA) is highly prevalent in obesity. Both obesity and OSA are associated with vascular endothelial inflammation and increased risk for cardiovascular diseases. We investigated directly whether the endothelial alterations that are attributed commonly to obesity are in fact related to OSA. METHODS AND RESULTS: Seventy-one subjects with a body mass index ranging from normal to obese underwent attended polysomnography. To assess vascular inflammation and oxidative stress directly, we quantified the expression of nuclear factor-kappaB and nitrotyrosine by immunofluorescence in freshly harvested venous endothelial cells. To evaluate basal endothelial nitric oxide (NO) production and activity, we quantified the expression of endothelial NO synthase (eNOS) and phosphorylated eNOS. Vascular reactivity was measured by brachial artery flow-mediated dilation. Expression of eNOS and phosphorylated eNOS and flow-mediated dilation were significantly lower, whereas expression of nitrotyrosine was significantly greater in OSA patients (n=38) than in OSA-free subjects (n=33) regardless of central adiposity. Expression of nuclear factor-kappaB was greater in obese OSA patients than in obese OSA-free subjects (P=0.004). Protein expression and flow-mediated dilation were not significantly affected by increasing body mass index or central obesity in OSA patients and in OSA-free subjects. After 4 weeks of continuous positive airway pressure therapy, flow-mediated dilation and expression of eNOS and phosphorylated eNOS significantly increased whereas expression of nitrotyrosine and nuclear factor-kappaB significantly decreased in OSA patients who adhered to continuous positive airway pressure >/=4 hours daily. CONCLUSIONS: Untreated OSA rather than obesity is a major determinant of vascular endothelial dysfunction, inflammation, and elevated oxidative stress in obese patients.

Coma with absent brainstem reflexes resulting from zolpidem overdose.

Zolpidem is a nonbenzodiazepine hypnotic with a favorable adverse effect profile. There are single reports of respiratory decompensation associated with zolpidem overdose. We report a case ofa young woman with depression who developed deep coma with respiratory failure and a loss of brainstem reflexes as a result of zolpidem overdose. Supportive management led to a complete recovery of neurologic function. Acute zolpidem overdose should be considered in the differential diagnosis of coma with absent brainstem reflexes.

Prenatal allergen and diesel exhaust exposure and their effects on allergy in adult offspring mice.

BACKGROUND: Multiple studies have suggested that prenatal exposure to either allergens or air pollution may increase the risk for the development of allergic immune responses in young offspring. However, the effects of prenatal environmental exposures on adult offspring have not been well-studied. We hypothesized that combined prenatal exposure to Aspergillus fumigatus (A. fumigatus) allergen and diesel exhaust particles will be associated with altered IgE production, airway inflammation, airway hyperreactivity (AHR), and airway remodeling of adult offspring. METHODS: Following sensitization via the airway route to A. fumigatus and mating, pregnant BALB/c mice were exposed to additional A. fumigatus and/or diesel exhaust particles. At age 9-10 weeks, their offspring were sensitized and challenged with A. fumigatus. RESULTS: We found that adult offspring from mice that were exposed to A. fumigatus or diesel exhaust particles during pregnancy experienced decreases in IgE production. Adult offspring of mice that were exposed to both A. fumigatus and diesel exhaust particles during pregnancy experienced decreases in airway eosinophilia. CONCLUSION: These results suggest that, in this model, allergen and/or diesel administration during pregnancy may be associated with protection from developing systemic and airway allergic immune responses in the adult offspring.

Inflammation, oxidative stress, and repair capacity of the vascular endothelium in obstructive sleep apnea.

BACKGROUND: Indirect evidence implicates endothelial dysfunction in the pathogenesis of vascular diseases associated with obstructive sleep apnea (OSA). We investigated directly whether dysfunction and inflammation occur in vivo in the vascular endothelium of patients with OSA. The effects of continuous positive airway pressure (CPAP) therapy on endothelial function and repair capacity were assessed. METHODS AND RESULTS: Thirty-two patients with newly diagnosed OSA and 15 control subjects were studied. Proteins that regulate basal endothelial nitric oxide (NO) production (endothelial NO synthase [eNOS] and phosphorylated eNOS) and inflammation (cyclooxygenase-2 and inducible NOS) and markers of oxidative stress (nitrotyrosine) were quantified by immunofluorescence in freshly harvested venous endothelial cells before and after 4 weeks of CPAP therapy. Vascular reactivity was measured by flow-mediated dilation. Circulating endothelial progenitor cell levels were quantified to assess endothelial repair capacity. Baseline endothelial expression of eNOS and phosphorylated eNOS was reduced by 59% and 94%, respectively, in patients with OSA compared with control subjects. Expression of both nitrotyrosine and cyclooxygenase-2 was 5-fold greater in patients with OSA than in control subjects, whereas inducible NOS expression was 56% greater. Expression of eNOS and phosphorylated eNOS significantly increased, whereas expression of nitrotyrosine, cyclooxygenase-2, and inducible NOS significantly decreased in patients who adhered to CPAP > or = 4 hours daily. Baseline flow-mediated dilation and endothelial progenitor cell levels were lower in patients than in control subjects, and both significantly increased in patients who adhered to CPAP > or = 4 hours daily. CONCLUSIONS: OSA directly affects the vascular endothelium by promoting inflammation and oxidative stress while decreasing NO availability and repair capacity. Effective CPAP therapy is associated with the reversal of these alterations.

Alveolar epithelial beta2-adrenergic receptors.

beta(2)-adrenergic receptors are present throughout the lung, including the alveolar airspace, where they play an important role for regulation of the active Na(+) transport needed for clearance of excess fluid out of alveolar airspace. beta(2)-adrenergic receptor signaling is required for up-regulation of alveolar epithelial active ion transport in the setting of excess alveolar edema. The positive, protective effects of beta(2)-adrenergic receptor signaling on alveolar active Na(+) transport in normal and injured lungs provide substantial support for the use of beta-adrenergic agonists to accelerate alveolar fluid clearance in patients with cardiogenic and noncardiogenic pulmonary edema. In this review, we summarize the role of beta(2)-adrenergic receptors in the alveolar epithelium with emphasis on their role in the regulation of alveolar active Na(+) transport in normal and injured lungs.

Clinical review: airway hygiene in the intensive care unit.

Maintenance of airway secretion clearance, or airway hygiene, is important for the preservation of airway patency and the prevention of respiratory tract infection. Impaired airway clearance often prompts admission to the intensive care unit (ICU) and can be a cause and/or contributor to acute respiratory failure. Physical methods to augment airway clearance are often used in the ICU but few are substantiated by clinical data. This review focuses on the impact of oral hygiene, tracheal suctioning, bronchoscopy, mucus-controlling agents, and kinetic therapy on the incidence of hospital-acquired respiratory infections, length of stay in the hospital and the ICU, and mortality in critically ill patients. Available data are distilled into recommendations for the maintenance of airway hygiene in ICU patients.

Interdependency of beta-adrenergic receptors and CFTR in regulation of alveolar active Na+ transport.

Beta-adrenergic receptors (betaAR) regulate active Na+ transport in the alveolar epithelium and accelerate clearance of excess airspace fluid. Accumulating data indicates that the cystic fibrosis transmembrane conductance regulator (CFTR) is important for upregulation of the active ion transport that is needed to maintain alveolar fluid homeostasis during pulmonary edema. We hypothesized that betaAR regulation of alveolar active transport may be mediated via a CFTR dependent pathway. To test this hypothesis we used a recombinant adenovirus that expresses a human CFTR cDNA (adCFTR) to increase CFTR function in the alveolar epithelium of normal rats and mice. Alveolar fluid clearance (AFC), an index of alveolar active Na+ transport, was 92% greater in CFTR overexpressing lungs than controls. Addition of the Cl- channel blockers NPPB, glibenclamide, or bumetanide and experiments using Cl- free alveolar instillate solutions indicate that the accelerated AFC in this model is due to increased Cl- channel function. Conversely, CFTR overexpression in mice with no beta1- or beta2-adrenergic receptors had no effect on AFC. Overexpression of a human beta2AR in the alveolar epithelium significantly increased AFC in normal mice but had no effect in mice with a non-functional human CFTR gene (Deltaphi508 mutation). These studies indicate that upregulation of alveolar CFTR function speeds clearance of excess fluid from the airspace and that CFTRs effect on active Na+ transport requires the betaAR. These studies reveal a previously undetected interdependency between CFTR and betaAR that is essential for upregulation of active Na+ transport and fluid clearance in the alveolus.

Upregulation of alveolar epithelial active Na+ transport is dependent on beta2-adrenergic receptor signaling.

Alveolar epithelial beta-adrenergic receptor (betaAR) activation accelerates active Na+ transport in lung epithelial cells in vitro and speeds alveolar edema resolution in human lung tissue and normal and injured animal lungs. Whether these receptors are essential for alveolar fluid clearance (AFC) or if other mechanisms are sufficient to regulate active transport is unknown. In this study, we report that mice with no beta1- or beta2-adrenergic receptors (beta1AR-/-/beta2AR-/-) have reduced distal lung Na,K-ATPase function and diminished basal and amiloride-sensitive AFC. Total lung water content in these animals was not different from wild-type controls, suggesting that betaAR signaling may not be required for alveolar fluid homeostasis in uninjured lungs. Comparison of isoproterenol-sensitive AFC in mice with beta1- but not beta2-adrenergic receptors to beta1AR-/-/beta2AR-/- mice indicates that the beta2AR mediates the bulk of beta-adrenergic-sensitive alveolar active Na+ transport. To test the necessity of betaAR signaling in acute lung injury, beta1AR-/-/beta2AR-/-, beta1AR+/+/beta2AR-/-, and beta1AR+/+/beta2AR+/+ mice were exposed to 100% oxygen for up to 204 hours. beta1AR-/-/beta2AR-/- and beta1AR+/+/beta2AR-/- mice had more lung water and worse survival from this form of acute lung injury than wild-type controls. Adenoviral-mediated rescue of beta2-adrenergic receptor (beta2AR) function into the alveolar epithelium of beta1AR-/-/beta2AR-/- and beta1AR+/+/beta2AR-/- mice normalized distal lung beta2AR function, alveolar epithelial active Na+ transport, and survival from hyperoxia. These findings indicate that betaAR signaling may not be necessary for basal AFC, and that beta2AR is essential for the adaptive physiological response needed to clear excess fluid from the alveolar airspace of normal and injured lungs.

Na,K-ATPase overexpression improves alveolar fluid clearance in a rat model of elevated left atrial pressure.

BACKGROUND: Acute elevation of left atrial pressure (LAP) increases extravascular water and impairs active Na(+) transport in rat lungs. We have reported that overexpression of Na,K-ATPase subunit genes in the alveolar epithelium increases alveolar fluid clearance (AFC) in normal and injured rat lungs with normal LAP. We reasoned that adenovirus-mediated transfer of an Na,K-ATPase beta-subunit gene to the alveolar epithelium could improve AFC in rat lungs in the presence of acutely elevated LAP. METHODS AND RESULTS: Normal rats were infected with 4x10(9) plaque-forming units of E1a(-)/E3(-) recombinant adenoviruses that contained a cytomegalovirus promoter coupled to a rat Na,K-ATPase beta(1)-subunit cDNA (adbeta(1)) or no cDNA (adNull) 7 days before study. Na,K-ATPase alpha(1)- and beta(1)-subunit abundance in basolateral cell membranes isolated from the peripheral lung was significantly increased in adbeta(1)-infected lungs compared with sham and adNull-infected controls. In all groups, elevation of LAP reduced membrane-bound Na,K-ATPase abundance; however, abundance in adbeta(1)-infected lungs remained greater than in controls. AFC, measured with a fluid-filled isolated lung preparation in the presence of elevated LAP (15 cmH(2)O), in Na,K-ATPase beta(1)-subunit-overexpressing lungs was up to 100% greater than in controls and was not different from rats studied at normal LAP (0 cmH(2)O). CONCLUSIONS: These data suggest that alveolar overexpression of an Na,K-ATPase beta(1)-subunit can counteract downregulation of membrane-bound solute transporters owing to elevated pulmonary vascular pressures and can restore active Na(+) transport and AFC in this rat model of acute hydrostatic pulmonary edema.

Potential genetic therapies for acute lung injury.

Acute lung injury (ALI) is a common, highly lethal acquired disorder that affects over one hundred thousand people each year and for which there are no specific therapies. Extensive investigations in experimental models and humans with ALI have identified several maladaptive host responses and dysregulated protein systems that offer therapeutic opportunities for genetic intervention. Several lines of evidence suggest that gene transfer can be used to deliver protective proteins that improve alveolar epithelial and/or endothelial cell function or immunomodulators that augment lung defense mechanisms and speed clearance of infection. In many instances, gene transfer is the only avenue for producing localized expression of these pharmaceuticals. This article reviews recent translational, animal-based studies that tested the use of gene and cell based therapies to ameliorate or prevent ALI. The lack of effective therapies for ALI and the approachability of the lung for local gene transfer suggest that ALI is a unique example of an acute disease process that is suitable for gene therapy.

Quantitation of pulmonary transgene expression with PET imaging.

UNLABELLED: PET imaging represents a promising approach for noninvasive monitoring of reporter gene expression in living subjects. We evaluated the relationship between various methods of quantifying the imaging signal and in vitro assays of the expression of a PET reporter gene (a mutant Herpes simplex virus-1 thymidine kinase (mHSV1-tk); 9-(4-(18)F-fluoro-3-hydroxymethylbutyl)guanine ((18)F-FHBG) was used as the PET reporter probe. METHODS: In 14 rats, pulmonary gene transfer was performed by intratracheal administration of various amounts of an adenovector containing a fusion gene encoding for mHSV1-tk and an enhanced green fluorescent protein. Three days later, the animals were divided into 2 groups. One group (n = 7) did not receive any other interventions. The other group was treated with alpha-naphthylthiourea (ANTU) to increase pulmonary vascular permeability. All rats were injected intravenously with (18)F-FHBG. Two additional rats in both groups received a null adenovector and served as controls. In the normal rats, repetitive blood samples were obtained and PET imaging was performed simultaneously using a dynamic imaging protocol. Rate constants estimating (18)F-FHBG transport (K(1)) or trapping (k(3)) within target cells were generated by compartmental modeling. After euthanasia, pulmonary uptake of (18)F-FHBG was determined using a gamma-counter in all rats, and in vitro assays of transgene expression were performed on lung tissue. RESULTS: In normal rats, pulmonary uptake of (18)F-FHBG increased as thymidine kinase (TK) activity increased only at low levels of mHSV1-tk expression and then plateaued as TK activity continued to increase. Compartmental modeling failed to improve the correlation with in vitro assays of transgene expression. However, a linear relationship was obtained between the pulmonary uptake of (18)F-FHBG and in vitro assays of TK activity in rats treated with ANTU. CONCLUSION: In rodent lungs, (18)F-FHBG uptake appears to be a function of both transport into tissues expressing the transgene as well as the level of transgene expression itself.

Role of vasopressin in the management of septic shock.

Vasopressin is a potent vasopressor for improving organ perfusion during septic shock. The rationale for the use of vasopressin is its relative deficiency of plasma levels and hypersensitivity to its vasopressor effects during septic shock. Growing evidence suggests that low-dose (<0.04 U/min) vasopressin is safe and effective for the treatment of vasodilatory shock. Although it is being used more frequently, there are no randomized clinical trials comparing vasopressin as a first-line agent to commonly used vasopressors. However, vasopressin causes arterial smooth muscle cell contraction through a non-catecholamine receptor pathway, thus it represents an attractive adjunct to the management of septic shock, especially when catecholamines are ineffective.

Management strategies to effect change in intensive care units: lessons from the world of business. Part I. Targeting quality improvement initiatives.

The business community has developed strategies to ensure the quality of the goods or services they produce and to improve the management of multidisciplinary work teams. With modification, many of these techniques can be imported into intensive care units (ICUs) to improve clinical operations and patient safety. In Part I of a three-part ATS Seminar series, we argue for adopting business management strategies in ICUs and set forth strategies for targeting selected quality improvement initiatives. These tools are relevant to health care today as focus is placed on limiting low-value care and measuring, reporting, and improving quality. In the ICU, the complexity of illness and the need to standardize processes make these tools even more appealing. Herein, we highlight four techniques to help prioritize initiatives. First, the "80/20 rule" mandates focus on the few (20%) interventions likely to drive the majority (80%) of improvement. Second, benchmarking--a process of comparison with peer units or institutions--is essential to identifying areas of strength and weakness. Third, root cause analyses, in which structured retrospective reviews of negative events are performed, can be used to identify and fix systems errors. Finally, failure mode and effects analysis--a process aimed at prospectively identifying potential sources of error--allows for systems fixes to be instituted in advance to prevent negative outcomes. These techniques originated in fields other than health care, yet adoption has and can help ICU managers prioritize issues for quality improvement.

Management strategies to effect change in intensive care units: lessons from the world of business. Part III. Effectively effecting and sustaining change.

Reaping the optimal rewards from any quality improvement project mandates sustainability after the initial implementation. In Part III of this three-part ATS Seminars series, we discuss strategies to create a culture for change, improve cooperation and interaction between multidisciplinary teams of clinicians, and position the intensive care unit (ICU) optimally within the hospital environment. Coaches are used throughout other industries to help professionals assess and continually improve upon their practice; use of this strategy is as of yet infrequent in health care, but would be easily transferable and potentially beneficial to ICU managers and clinicians alike. Similarly, activities focused on improving teamwork are commonplace outside of health care. Simulation training and classroom education about key components of successful team functioning are known to result in improvements. In addition to creating an ICU environment in which individuals and teams of clinicians perform well, ICU managers must position the ICU to function well within the hospital system. It is important to move away from the notion of a standalone ("siloed") ICU to one that is well integrated into the rest of the institution. Creating a "pull-system" (in which participants are active in searching out needed resources and admitting patients) can help ICU managers both provide better care for the critically ill and strengthen relationships with non-ICU staff. Although not necessary, there is potential upside to creating a unified critical care service to assist with achieving these ends.

Management strategies to effect change in intensive care units: lessons from the world of business. Part II. Quality-improvement strategies.

The success of quality-improvement projects relies heavily on both project design and the metrics chosen to assess change. In Part II of this three-part American Thoracic Society Seminars series, we begin by describing methods for determining which data to collect, tools for data presentation, and strategies for data dissemination. As Avedis Donabedian detailed a half century ago, defining metrics in healthcare can be challenging; algorithmic determination of the best type of metric (outcome, process, or structure) can help intensive care unit (ICU) managers begin this process. Choosing appropriate graphical data displays (e.g., run charts) can prompt discussions about and promote quality improvement. Similarly, dashboards/scorecards are useful in presenting performance improvement data either publicly or privately in a visually appealing manner. To have compelling data to show, ICU managers must plan quality-improvement projects well. The second portion of this review details four quality-improvement tools-checklists, Six Sigma methodology, lean thinking, and Kaizen. Checklists have become commonplace in many ICUs to improve care quality; thinking about how to maximize their effectiveness is now of prime importance. Six Sigma methodology, lean thinking, and Kaizen are techniques that use multidisciplinary teams to organize thinking about process improvement, formalize change strategies, actualize initiatives, and measure progress. None originated within healthcare, but each has been used in the hospital environment with success. To conclude this part of the series, we demonstrate how to use these tools through an example of improving the timely administration of antibiotics to patients with sepsis.

Prenatal and postnatal polycyclic aromatic hydrocarbon exposure, airway hyperreactivity, and Beta-2 adrenergic receptor function in sensitized mouse offspring.

Despite data associating exposure to traffic-related polycyclic aromatic hydrocarbons (PAH) in asthma, mechanistic support has been limited. We hypothesized that both prenatal and early postnatal exposure to PAH would increase airway hyperreactivity (AHR) and that the resulting AHR may be insensitive to treatment with a ß 2AR agonist drug, procaterol. Further, we hypothesized that these exposures would be associated with altered ß 2AR gene expression and DNA methylation in mouse lungs. Mice were exposed prenatally or postnatally to a nebulized PAH mixture versus negative control aerosol 5 days a week. Double knockout ß 2AR mice were exposed postnatally only. Prenatal exposure to PAH was associated with reduced ß 2AR gene expression among nonsensitized mice offspring, but not increases in DNA methylation or AHR. Postnatal exposure to PAH was borderline associated with increased AHR among sensitized wildtype, but not knockout mice. In the first study that delivers PAH aerosols to mice in a relatively physiological manner, small effects on AHR and ß 2AR gene expression, but not ß 2AR agonist drug activity, were observed. If confirmed, the results may suggest that exposure to PAH, common ambient urban pollutants, affects ß 2AR function, although the impact on the efficacy of ß 2AR agonist drugs used in treating asthma remains uncertain.