Response of the lungs to aspiration

Implementation of a free water protocol at a long term acute care hospital

This feasibility study aimed to trial a Free Water Protocol (FWP) for patients with thin liquid dysphagia in the Long-Term Acute Care Hospital (LTACH) setting. Patients with dysphagia are often prescribed thickened liquids to avoid or mitigate aspiration. While this clinical intervention can minimize the risk of aspiration pneumonia (PNA), it is generally not well received by patients. As such, the goal of this study was to determine if patients who knowingly aspirate thin liquids can safely tolerate thin liquid water, and if so, to what degree of benefit. The study assessed for adverse events, fluid intake, hydration status, quality of life, and overall swallow function outcomes. These measurements were taken over a 7 day trial period using inventories, lab work, clinical judgment, and observation. Ten participants were enrolled in this study with 9 having sufficient data for analysis (n = 9). No adverse events related to the FWP were observed, and patients saw improved total fluid intake (P = 0.0074), swallow-related quality of life (P = 0.0273), and overall swallow function (P = 0.0002). The results in this feasibility study allowed for the hospital wide implementation of the FWP and laid out the groundwork for future studies looking at longitudinal effects of a FWP.

Mechanistic Understanding of Lung Inflammation: Recent Advances and Emerging Techniques

Acute respiratory distress syndrome (ARDS) is a life-threatening lung injury characterized by an acute inflammatory response in the lung parenchyma. Hence, it is considered as the most appropriate clinical syndrome to study pathogenic mechanisms of lung inflammation. ARDS is associated with increased morbidity and mortality in the intensive care unit (ICU), while no effective pharmacological treatment exists. It is very important therefore to fully characterize the underlying pathobiology and the related mechanisms, in order to develop novel therapeutic approaches. In vivo and in vitro models are important pre-clinical tools in biological and medical research in the mechanistic and pathological understanding of the majority of diseases. In this review, we will present data from selected experimental models of lung injury/acute lung inflammation, which have been based on clinical disorders that can lead to the development of ARDS and related inflammatory lung processes in humans, including ventilation-induced lung injury (VILI), sepsis, ischemia/reperfusion, smoke, acid aspiration, radiation, transfusion-related acute lung injury (TRALI), influenza, Streptococcus (S.) pneumoniae and coronaviruses infection. Data from the corresponding clinical conditions will also be presented. The mechanisms related to lung inflammation that will be covered are oxidative stress, neutrophil extracellular traps, mitogen-activated protein kinase (MAPK) pathways, surfactant, and water and ion channels. Finally, we will present a brief overview of emerging techniques in the field of omics research that have been applied to ARDS research, encompassing genomics, transcriptomics, proteomics, and metabolomics, which may recognize factors to help stratify ICU patients at risk, predict their prognosis, and possibly, serve as more specific therapeutic targets.

Treatment burden associated with the intake of thickened fluids

The implementation of thickened fluids in patients with dysphagia is widely considered an effective strategy for safe and physiologically improved swallow. However, there is limited evidence to suggest that this intervention reduces the risk of dysphagia-related complications including aspiration pneumonia. In addition, there is growing evidence that this approach is associated with adverse clinical effects including dehydration, malnutrition and reduced health-related quality of life. This review summarises the rationale for thickened fluids, the evidence base (or lack thereof) underpinning their use, and current guideline recommendations.

Educational aims

To review the evidence base for thickened fluids in the management of dysphagia.To examine the evidence that thickened fluids reduce aspiration pneumonia.To provide an overview of the advantages and disadvantages of thickened fluids in the management of dysphagia.

Implementing oral care to reduce aspiration pneumonia amongst patients with dysphagia in a South African setting

Oral care is a crucial routine for patients with dysphagia that, when completed routinely, can prevent the development of aspiration pneumonia. There is no standardised protocol for oral care within government hospitals in South Africa. This study aimed to investigate the outcome of an oral care protocol. Participants were patients with oropharyngeal dysphagia, with either stroke or traumatic brain injury as the underlying medical pathology, and nurses. All participants were recruited from one tertiary level government hospital in Gauteng, South Africa. 139 nurses participated in the study and received training on the oral care protocol. There were two groups of participants with oropharyngeal dysphagia. Group one (study group, n = 23) was recruited by consecutive sampling, received regular oral care and were not restricted from drinking water; however, all other liquids were restricted. Group two (comparison group, n = 23) was recruited via a retrospective record review, received inconsistent oral care and were placed on thickened liquids or liquid restricted diets. Results showed that a regimen of regular oral care and free water provision when combined with dysphagia intervention did prevent aspiration pneumonia in patients with oropharyngeal dysphagia. The article highlights two key findings: that regular and routine oral care is manageable within an acute government hospital context and a strict routine of oral care can reduce aspiration pneumonia in patients with oropharyngeal dysphagia. An implication from these findings is confirmation that teamwork in acute care settings in developing contexts must be prioritised to improve dysphagia management and patient prognosis.

ICU-acquired swallowing disorders

OBJECTIVES

Patients hospitalized in the ICU can frequently develop swallowing disorders, resulting in an inability to effectively transfer food, liquids, and pills from their mouth to stomach. The complications of these disorders can be devastating, including aspiration, reintubation, pneumonia, and a prolonged hospital length of stay. As a result, critical care practitioners should understand the optimal diagnostic strategies, proposed mechanisms, and downstream complications of these ICU-acquired swallowing disorders.

DATA SOURCES

Database searches and a review of the relevant medical literature.

DATA SYNTHESIS

A significant portion of the estimated 400,000 patients who annually develop acute respiratory failure, require endotracheal intubation, and survive to be extubated are determined to have dysfunctional swallowing. This group of swallowing disorders has multiple etiologies, including local effects of endotracheal tubes, neuromuscular weakness, and an altered sensorium. The diagnosis of dysfunctional swallowing is usually made by a speech-language pathologist using a bedside swallowing evaluation. Major complications of swallowing disorders in hospitalized patients include aspiration, reintubation, pneumonia, and increased hospitalization. The national yearly cost of swallowing disorders in hospitalized patients is estimated to be over $500 million. Treatment modalities focus on changing the consistency of food, changing mealtime position, and/or placing feeding tubes to prevent aspiration.

CONCLUSIONS

Swallowing disorders are costly and clinically important in a large population of ICU patients. The development of effective screening strategies and national diagnostic standards will enable further studies aimed at understanding the precise mechanisms for these disorders. Further research should also concentrate on identifying modifiable risk factors and developing novel treatments aimed at reducing the significant burden of swallowing dysfunction in critical illness survivors.

Pulmonary edema due to oral gavage in a toxicological study related to aquaporin-1, -4 and -5 expression

A one-time oral gavage can be enough to cause of alveologenic edema with higher expression of AQP-1 and -4 than that with repeated-dose oral gavage, which caused both profound perivascular edema and hydrostatic pressure edema, while AQP-5 was similarly expressed. The alteration of AQPs expression was probably related to alveolar fluid clearance across the alveolar and bronchiolar epithelium in different stages of lung injury. The results clarified the type of lung edema in acute and sub-chronic toxicity studies without treatment related effect of tested material. The pathogenesis of pulmonary edema due to oral gavage toxicological study is associated with the cellular immune response to the reflux materials. Mast cell and leukocyte accumulation may contribute to increase vascular permeability leading to permeability edema. The increase in alveolar septum epithelium, perivascular and peribronchial cuffing, accumulation alveolar lipid containing macrophage and medial hyperplasia of the pulmonary artery might have been caused to increase airway resistance, which resulted in hydrostatic pressure edema.

Outcomes of a pilot water protocol project in a rehabilitation setting

There is considerable clinical interest in the risks and benefits of offering oral water intake, in the form of water protocols, to patients with thin-liquid dysphagia. We describe the design and implementation of a water protocol for patients in a rehabilitation setting with videofluoroscopically confirmed thin-liquid aspiration. The GF Strong Water Protocol (GFSWP) is an interdisciplinary initiative, with roles and accountabilities specified for different members of the interprofessional health-care team. Rules of the water protocol specify mode of water access (independent, supervised), the implementation of any safe swallowing strategies recommended on the basis of the patient's videofluoroscopy, and procedures for evaluating and addressing oral care needs. Trial implementation of the water protocol in 15 participants showed that they remained free of adverse events, including pneumonia, over the course of an initial 14-day trial and continuing until discharge from the facility (range = 13-108 days). Seven participants were randomly assigned to a 14-day control phase in which they received standard care (without water access). Fluid intake measures taken after the oral water intake phase were increased (mean = 1,845 cc; 95% confidence interval: 1,520-2,169 cc) compared to those in the control phase (mean = 1,474 cc; 95% CI: 1,113-1,836 cc), with oral water intake measures comprising, on average, 563 cc (range = 238-888 cc) of the total post water trial fluid intake values. Fluid intake increased at least 10% of the calculated fluid requirements in 11/15 participants who received oral water access. These participants reported favorable quality-of-life outcomes, measured using the Swal-QOL. These findings support the implementation of the GFSWP, including its exclusion criteria, rules, and plans of care, for rehabilitation patients who aspirate thin liquids.

Relevance of GERD in lung transplant patients

Lung transplantation has become a valuable treatment for end-stage pulmonary disorders in an attempt to improve quality of life and extend survival. Development of chronic rejection, also known as bronchiolitis obliterans syndrome (BOS), is responsible for the vast majority of deaths after lung transplantation. Up to 50% of lung transplant patients develop BOS within the first 5 years after transplantation. A high prevalence of gastroesophageal reflux and aspiration of gastric components has been described after lung transplantation. Reflux and aspiration have been implicated in the development of BOS and antireflux surgery has been proposed; however, the causal relationship with BOS and the impact of reflux in lung transplantation survival needs to be further elucidated.

Bile acid-induced lung injury in newborn infants: a bronchoalveolar lavage fluid study

OBJECTIVES

Neonatal respiratory distress syndrome is associated with intrahepatic cholestasis of pregnancy, and bile acids may play a major role in neonatal bile acid pneumonia. Our aim was to demonstrate the bile acid presence in the bronchoalveolar lavage fluid of neonates affected by respiratory distress syndrome who were born from intrahepatic cholestasis of pregnancy and to investigate bile acid mechanisms of action in acute lung injury.

METHODS

In this prospective study, we enrolled 10 neonates delivered from intrahepatic cholestasis of pregnancy, affected by respiratory distress syndrome requiring mechanical ventilation (intrahepatic cholestasis of pregnancy group) and 2 control groups. The first group consisted of 20 infants with respiratory distress syndrome delivered from pregnancies without any sign of intrahepatic cholestasis of pregnancy (respiratory-distress-syndrome group), and the second group included 20 neonates with no lung disease who were ventilated for extrapulmonary reasons (no-lung-disease group). We measured bile acid and pH in the bronchoalveolar lavage fluid and serum bile acid levels in the first 24 hours of life.

RESULTS

Bile acids were measurable in the bronchoalveolar lavage fluid of all of the infants in the intrahepatic cholestasis of pregnancy group but were absent in the 2 control groups. Bronchoalveolar lavage fluid pH was not different among the 3 groups. Infants in the intrahepatic-cholestasis-of-pregnancy group had significantly higher serum bile acid levels compared with those in both of the control groups.

CONCLUSIONS

Bile acids are detectable in the bronchoalveolar lavage fluid of newborns from intrahepatic cholestasis of pregnancy affected by respiratory distress syndrome. Elevated serum bile acid levels in these infants allow us to hypothesize that bile acid reaches the lung after an uptake from the circulation. These findings strongly support a role for bile acid in causing bile acid pneumonia.

Localization of aquaporin water channels in the airway of the musk shrew (Suncus murinus) and the rat

Aquaporins (AQPs) constitute a family of water channels that facilitate membrane water permeability in various tissues of animals. In this study, we compared the expression and localization of AQPs in the respiratory system of the musk shrew (Suncus murinus), which is an insectivore, and the rat by immunohistochemical methods. In both the musk shrew and the rat, AQP1 was expressed throughout the airway in endothelial cells of subepithelial blood vessels and in nasal submucosal fibroblasts. AQP3 and AQP4 were detected in neither the epithelium nor the subepithelial layer of the musk shrew airway, but were abundant in the rat airway epithelium. Musk shrew AQP5 was distributed in the superficial epithelial cells facing the airspaces and in submucosal glandular cells, but, unlike in the rat, not in lung alveolar cells. Additionally, the expression patterns of AQP4 and AQP5 of the musk shrew were partly similar to those of the human previously reported, absence of AQP4 and presence of AQP5 in the upper airway. The expression differences of AQPs between species in the airway indicate that the physiological importance of each AQP may be different in each species.

Use of thickened liquids in skilled nursing facilities

OBJECTIVE

Long-term care residents are routinely provided with thickened liquids for the management of dysphagia. The objective of this study was to identify the prevalence of thickened liquid use in skilled nursing facilities.

DESIGN

Facility-wide data were provided by staff at 252 randomly selected skilled nursing facilities owned by 11 multifacility providers. The sample represented 25,470 residents and approximately 20% of all freestanding skilled nursing facilities nationwide.

MAIN OUTCOMES MEASURES

Data regarding prevalence of thickened liquid use and facility characteristics were collected during May 2002. Statistical analysis Descriptive statistics included national and regional averages and national percentile distributions.

RESULTS

A mean of 8.3% (range 0% to 28%) of residents were receiving thickened liquids, with considerable variation between Centers for Medicare and Medicaid Services regions. Of those receiving thickened liquids, on average 60% received "nectar/syrup" thick, 33% received "honey" thick, and 6% received "pudding/spoon" thick, although the frequencies with which each thickness was prescribed varied widely between facilities (range 0% to 100%). Thickened water was provided to residents in 91.6% of facilities. Nationally, registered dietitian staffing levels were lower on average than speech language pathologist staffing levels.

CONCLUSIONS

Thickened liquids are provided to a significant segment of the skilled nursing facility resident population. In the absence of outcomes-based practice standards to guide administrative decisions related to the provision of thickened liquids, dietetics professionals may find regional and national norms helpful for quality assurance processes and to inform resource management decisions in clinical staffing and foodservice.

Interstitial lung disease and gastroesophageal reflux

Gastroesophageal reflux (GER) has been associated with a number of interstitial lung diseases, including systemic sclerosis and idiopathic pulmonary fibrosis. Systemic sclerosis results in both pulmonary and esophageal manifestations, and studies have shown a correlation, but no causal relation, between GER and pulmonary fibrosis in this condition. The role of GER in idiopathic pulmonary fibrosis has recently been studied using esophageal pH monitoring, and the results show high prevalence of GER compared with normal individuals and patients with other interstitial lung diseases of known cause. Aggressive, long-term therapy of GER and evaluation of its effect on pulmonary disease will allow determination of the real influence of GER on idiopathic pulmonary fibrosis. Additional outcomes-based studies and therapeutic trials are needed to clarify the association between GER and interstitial lung diseases.

Airway surface liquid pH in well-differentiated airway epithelial cell cultures and mouse trachea

Airway surface liquid (ASL) pH has been proposed to be important in the pathophysiology of cystic fibrosis, asthma, and cough. Ratio image analysis was used to measure pH in the ASL after staining with the fluorescent pH indicator 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF)-dextran. ASL pH in bovine airway cell cultures grown at an air-liquid interface was 6.98 +/- 0.06 in the absence and 6.81 +/- 0.04 in the presence of HCO/CO(2). Steady-state ASL pH changed in parallel to changes in bath pH and was acidified by Na(+) or Cl(-) replacement but was not affected by the inhibitors amiloride, glibenclamide, or 4,4'-dinitrostilbene-2,2'-disulfonic acid. In response to sudden acidification or alkalization of the ASL by approximately 0.4 pH units by HCl/NaOH, ASL pH recovered to its initial value at a rate of 0.035 pH units/min (-HCO) and 0.060 pH units/min (+HCO); the pH recovery rate was reduced by amiloride and H(2)DIDS. In anesthetized mice in which the trachea was surgically exposed for measurement of BCECF-dextran fluorescence through the translucent tracheal wall, ASL pH was 7.14 +/- 0.01. ASL pH was sensitive to changes in blood pH created by metabolic (HCl or NaHCO(3) infusion) or respiratory (hyperventilation, hypoventilation) mechanisms. ASL pH is thus primarily determined by basolateral fluid pH, and H(+)/OH(-) transport between the ASL and basolateral fluid involves amiloride-sensitive Na(+)/H(+) exchange and stilbene-sensitive Cl(-)/HCO exchange. The rapid response of ASL pH to changes in systemic acid-base status may contribute to airway hypersensitivity in asthma and other airway diseases.