Aspiration Pneumonia

Aspiration Pneumonia

Aspiration pneumonia is a lower respiratory tract infection that results from inhalation of foreign material, often gastric and oropharyngeal contents. It is important to distinguish this from a similar entity, aspiration with chemical pneumonitis, as treatment approaches may differ. An evolving understanding of the human microbiome has shed light on the pathogenesis of aspiration pneumonia, suggesting that dysbiosis, repetitive injury, and inflammatory responses play a role in its development. Risk factors for aspiration events involve a complex interplay of anatomical and physiological dysfunctions in the nervous, gastrointestinal, and pulmonary systems. Current treatment strategies have shifted away from anaerobic organisms as leading pathogens. Prevention of aspiration pneumonia primarily involves addressing oropharyngeal dysphagia, a significant risk factor for aspiration pneumonia, particularly among elderly individuals and those with cognitive and neurodegenerative disorders.

Rapid sequence induction of anesthesia: works in progress and steps forward with focus to oxygenation and monitoring techniques

The description of the main scientifically consolidated innovations in recent years on Rapid Sequence Induction have been the subject of this narrative review. Data sources were PubMed, EMBASE, Web of Science, the Cochrane Central Register of Controlled Trials, and ClinicaTrials.gov, searched up to March 21st, 2023; rapid sequence induction and anesthesia were used as key word for the research. In recent years at least three significant innovations which have improved the procedure: firstly the possibility of using drugs which rapidly reverse the action of the myorelaxants and which have made it possible to give up the use of succinylcholine, replaced by rocuronium; secondly, the possibility of using much more effective pre-oxygenation methods than in the past, also through apneic oxygenation techniques which allow longer apnea time, and finally new monitoring systems much more effective than pulse oximetry in identifying and predicting periprocedural hypoxemia and indicating the need for ventilation in patients at risk of hypoxemia and preventing it. The description of three main scientifically consolidated innovations in recent years, in pharmacology, oxygen method of administration and monitoring, have been the subject of this narrative review.

Persistent Hiccups: An Unusual Presentation of Aspiration Pneumonia in the Elderly

Persistent hiccups manifesting as the sole symptom of aspiration pneumonia is a rare occurrence. Approximately 10 cases have been reported in the last 15 years. Hiccups are defined as persistent if it occurs beyond 48 hours and intractable if it occurs continuously for one month. We highlight a case of an elderly man diagnosed with a subacute ischemic infarct of the right occipital lobe with a preserved gag reflex and swallow reflex. The patient’s persistent hiccups began eight hours after an emetic episode. Typical signs of pneumonia were absent. Chest x-ray revealed bilateral lower lobe pulmonary infiltrates and he was treated aggressively with intravenous antibiotics and chlorpromazine. He made a full recovery and was discharged four days later.

Infection

Community-Acquired Pneumonia (CAP) is the first leading cause of death due to infection worldwide.Many gram-positive, gram-negative bacteria, funguses and viruses can cause the infectious pulmonary disease, and the severity of pneumonia depends on the balance between the microorganism charge, the body immunity defenses and the quality of the underlying pulmonary tissue. The microorganisms may reach the lower respiratory tract from inhaled air or from infected oropharyngeal secretions. The same organism may produce several different patterns that depend on the balance between the microorganism charge and the body immunity defenses.CAP is classified into three main groups: lobar pneumonia, bronchopneumonia and interstitial pneumonia.Lobar pneumonia is characterized by the filling of alveolar spaces by edema full of white and inflammatory cells. Necrotizing pneumonia consists of a fulminant process associated with focal areas of necrosis that results in abscesses. Bronchopneumonia or lobular pneumonia, is characterized by a peribronchiolar inflammation with thickening of peripheral bronchial wall, the diffusion of inflammation to the centrilobular alveolar spaces and development of nodules.The interstitial pneumonia represents with the destruction and esfoliation of the respiratory ciliated and mucous cells. The interstitial septa, the bronchial and bronchiolar walls become thickened for the inflammation process and lymphocytes interstitial infiltrates.Chest radiography represents an important initial examination in all patients suspected of having pulmonary infection and for monitoring response to therapy.Its role is to identify the pulmonary opacities, their internal characteristics and distribution, pleural effusion and presence of other complications as abscesses and pneumothorax.High spatial CT resolution allows accurate assessment of air space inflammation.The CT findings include nodules, interlobular septal thickening, intralobular reticular opacities, ground-glass opacities, tree-in-bud pattern, lobar-segmental consolidation, lobular consolidation, abscesses, pneumatocele, pleural effusion, pericardial effusion, mediastinal and hilar lymphoadenopaties, airway dilatation and emphysema.

Interstitial pneumonitis after betadine aspiration

Disinfection of the face and mucosa lined surfaces of the nose and mouth using a povidone-iodine (PI) or Betadine solution is common practice among head and neck surgeons. Povidone-iodine, which is a highly effective broad-spectrum antibiotic effective against bacteria, viruses, fungi, and protozoa, decreases the risk of postoperative surgical wound infection. We report a case of PI aspiration causing an acute chemical pneumonitis after preoperative disinfection of the oral cavity and nasopharynx in preparation for cleft palate repair. As a result of the inflammatory response, the patient required positive pressure mechanical ventilation and a prolonged stay in the pediatric intensive care unit. The patient was safely extubated on hospital day 7 and discharged on hospital day 10 without any long-term sequelae on follow-up. We also review the 3 other reported cases of PI aspiration pneumonitis. Based on our case report and literature review, we conclude that PI aspiration is associated with a high rate of morbidity; however, this should not preclude the use of PI before surgery, given its effectiveness as an oral disinfectant and the exceedingly low incidence of aspiration.

Portable suction unit failure in a rural EMS system

INTRODUCTION

Portable suction units used by EMS personnel are utilized infrequently and often are powered by batteries. Lack of use and inspection often results in failure of the device when it is needed. The purpose of this study was to examine the incidence of portable suction unit failure in a rural EMS system and to identify the reasons for failures.

METHODS

A convenience sample was obtained through both random inspections by the staff of a regional EMS council and data from twice monthly checks reported by respective EMS agencies following a standard protocol for each unit. A standard protocol was used, including checking the vacuum level on each suction unit and inspecting the tubing, canister, and battery. Each inspector assessed whether the unit was capable of achieving 300 mmHg of suction within four seconds. Also, the unit was inspected for any signs of misalignment or dry rot of the gasket, kinking of suction hose, damage to the suction canister, weak/dead battery, or defective pump. Findings were recorded.

RESULTS

Over a two-year period, 9,631 suction unit inspections were completed. There were 233 failures (2.4%) noted. The majority (126, 54.1%) were due to battery failure. Seventy-three units failed due to other reasons (not recorded, switch failure, battery not seated). Ten inspections failed due to incorrect assembly. Nineteen inspections failed due to defects with the suction canister. Five inspections failed due to kinked/disconnected suction tubing.

CONCLUSION

Only a relatively small percentage of inspections of suction units revealed failures (4.6% Advanced Life Support, 8.6% Basic Life Support) using the above-stated criteria. However, given the importance of airway management and potential complications associated with airway compromise, including aspiration pneumonia, hypoxia, and hemodynamic instability, this is of concern relative to the morbidity and mortality that could be related to airway failure. Due to the relative infrequency of use and the nature of portable suction units, the potential for lack of maintenance and deficiencies in routine inspection may impact the functional status of these devices in EMS agencies. Clearly, improved documentation of battery installation date, charging in accordance with manufacturer recommendations, and thorough inspection of the portable suction unit in its entirety will ensure readiness of these devices. Additionally, more rigorous documentation and analysis of inspections should be a focus of EMS agencies.

Intensive-care unit lung infections: The role of imaging with special emphasis on multi-detector row computed tomography

Nosocomial pneumonia is the most frequent hospital-acquired infection. In mechanically ventilated patients admitted to an intensive-care unit as many as 7-41% may develop pneumonia. The role of imaging is to identify the presence, location and extent of pulmonary infection and the presence of complications. However, the poor resolution of bedside plain film frequently limits the value of radiography as an accurate diagnostic tool. To date, multi-detector row computed tomography with its excellent contrast resolution is the most sensitive modality for evaluating lung parenchyma infections.

Management of pulmonary aspiration

Pulmonary aspiration of gastric contents in the perioperative phase is associated with increased postoperative morbidity and mortality. For the management of aspiration, differentiation between acid-associated aspiration pneumonitis and aspiration pneumonia as a consequence of a secondary bacterial contamination is of crucial importance. The incidence of aspiration in elective surgery is 1 per 2000-3000 anaesthesias in adults. In children, it is slightly more common with 1 per 1200-2600 anaesthesias. In the context of emergency anaesthesias the incidence of aspiration is three to four times higher. The risk particularly increases with recent ingestion of solid food or fluids, with older patients, with pregnant women, and with consciousness-reduced patients. Besides giving a review of the pathophysiology, incidence, and the risk factors of aspiration, this article places emphasis on the practical management of this anaesthesia-associated complication. Cricoid pressure, as a non-evidence-based but clinically wide-spread method in the context of the prophylaxis of aspiration, is discussed critically. The main part deals with strategies to structure the management of aspiration by use of scientific concepts based on medical crisis management. For this, an algorithm based on current scientific investigations is presented.

Educating Nurses about Correct Application of Cricoid Pressure

ALTHOUGH THE APPLICATION of cricoid pressure is a technique that is performed almost daily in the OR, perioperative nurses may not be applying cricoid pressure correctly. THE PURPOSE of this quality improvement project was to develop an education program to assess perioperative nurses' skills and educate and train them regarding correct application of cricoid pressure. OF 51 PERIOPERATIVE NURSES who participated in a pretest, an education program, and a posttest, the number of participants who could apply the appropriate amount of pressure to the correct location increased from two (3.9%) on the pretest to 35 (68.6%) on the posttest.

Radiographic and CT Findings of Thoracic Complications after Pneumonectomy

Pneumonectomy is the treatment of choice for bronchogenic carcinoma and intractable end-stage lung diseases such as tuberculosis and bronchiectasis, but it is often followed by postoperative complications, which account for significant morbidity and mortality. Knowledge of the radiologic features of such complications is of critical importance for their early detection and prompt management. Complications of pneumonectomy are classified as early or late, depending on when they occur in relation to the hospitalization period. Early complications of pneumonectomy include pulmonary edema, bronchopleural fistula, pneumonia of the contralateral lung, empyema, and adult respiratory distress syndrome, which may occur separately or in combination. Late postpneumonectomy complications include recurrent disease, infection, effects of radiation therapy or chemotherapy, and surgical complications such as late-onset bronchopleural fistula, postpneumonectomy syndrome, and esophagopleural fistula. Sequential examinations with chest radiography after pneumonectomy are an invaluable method of screening for these complications, especially in the early postoperative period. When the radiographic findings are inconclusive, computed tomography is helpful for establishing a diagnosis and obtaining detailed information about the disease process.

Epidemiology and impact of aspiration pneumonia in patients undergoing surgery in Maryland, 1999-2000

OBJECTIVE

The epidemiology of aspiration pneumonia and its impact on clinical and economic outcomes in surgical patients are poorly defined. We sought to identify preoperative patient characteristics and surgical procedures that are associated with an increased risk for aspiration pneumonia and to determine the clinical and economic impact in hospitalized surgical patients.

DESIGN

Observational study using a state discharge database.

SETTING

All hospitals in Maryland.

PATIENTS

We obtained discharge data for 318,880 adult surgical patients in 52 Maryland hospitals from January 1, 1999, through December 31, 2000.

MEASUREMENTS AND MAIN RESULTS

The primary outcome variable was a discharge diagnosis of aspiration pneumonia. Unadjusted and adjusted analyses were performed to identify patient characteristics and surgical procedures associated with an increased risk for aspiration pneumonia and to determine the impact on intensive care unit admission, in-hospital mortality, hospital length of stay, and total hospital charges. The overall prevalence of aspiration pneumonia was 0.8%. The prevalence varied among hospitals (range, 0% to 1.9%) and by surgical procedure (range, <0.1% to 19.1%). Patient characteristics independently associated with an increased risk included: male sex, nonwhite race, age of >60 yrs vs. 18-29 yrs, dementia, chronic obstructive pulmonary disease, renal disease, malignancy, moderate to severe liver disease, and emergency room admission. In patients undergoing procedures other than tracheostomy, aspiration pneumonia was independently associated with an increased risk for admission to the intensive care unit (odds ratio, 4.0; 95% confidence interval, 3.0-5.1), in-hospital mortality (odds ratio, 7.6; 95% confidence interval, 6.5-8.9), longer hospital length of stay (estimated mean increase of 9 days; 95% confidence interval, 8-10), and increased total hospital charges (estimated mean increase of 22,000 US dollars; 95% confidence interval, 19,000 US dollars-25,000 US dollars).

CONCLUSIONS

Aspiration pneumonia occurs in approximately 1% of surgical patients and is associated with significant morbidity, mortality, and costs of care. Given that the rate of aspiration pneumonia varies among hospitals, we can improve the quality and reduce the costs of care by implementing strategies to reduce the rate of aspiration pneumonia.

Thoracic complications of esophageal disorders

Abnormalities of the esophagus are common, and complications associated with these disorders and diseases can involve the mediastinum, tracheobronchial tree, and lungs. The most common complications include mediastinitis secondary to esophageal perforation or postoperative anastomotic leak, or both; empyema due to fistula formation; and aspiration pneumonia. The authors reviewed the radiologic appearances of those and other common thoracic complications associated with esophageal disorders to facilitate early detection, diagnosis, and management. Computed tomographic (CT) findings of acute mediastinitis secondary to esophageal perforation may include esophageal thickening, extraluminal gas, pleural effusion, single or multiple abscesses, and extraluminal contrast medium. The radiologic manifestations of pneumonia secondary to tracheoesophageal fistula are variable, depending on the spread and severity of the aspiration. The most common radiographic pattern is that of bronchopneumonia with scattered air-space opacities. CT has been regarded as the imaging modality of choice for the evaluation of suspected esophagopleural fistula, because the site of communication between the pleural space and the esophagus can often be seen. An awareness of the radiologic manifestations of these complications is thus required to facilitate early diagnosis.

Radiographic and CT findings in complications following pulmonary resection

A variety of pulmonary resection techniques are currently available, including pneumonectomy (intrapleural, extrapleural, intrapericardial, and sleeve pneumonectomy), lobectomy, and limited resection (sleeve lobectomy, segmentectomy, nonanatomic parenchyma-sparing resection). However, pulmonary resection is often followed by postoperative complications that differ according to the type of surgery and the time elapsed since surgery was performed. The most common complications are bleeding, pulmonary edema, atelectasis, pneumonia, persistent air leak, bronchopleural fistula, and empyema. Other, less frequent complications include cardiac herniation, lung torsion, chylothorax, anastomotic dehiscence, wound infection, esophagopleural fistula, and recurrent tumor. The radiologist plays a major role in the diagnosis of various complications following pulmonary resection. Unfortunately, chest radiography has a relatively low diagnostic accuracy in the detection of these complications. When radiographic findings are subtle or equivocal, computed tomography frequently allows more accurate identification of the disease process. Several complications that follow pulmonary resection are life-threatening and require prompt management. Therefore, knowledge of the diverse radiologic appearances of these complications as well as familiarity with the clinical settings in which specific complications are likely to occur are vital for prompt, effective treatment.

Clinical aspiration-related practice patterns in the intensive care unit: a physician survey

OBJECTIVE

To characterize physician practice patterns regarding the clinical, microbiological, and antimicrobial-related events of suspected or documented aspiration and aspiration pneumonia within the intensive care unit.

DESIGN

National mail survey.

SETTING

University medical center.

STUDY POPULATION

Critical care physician members of the Society of Critical Care Medicine.

INTERVENTIONS

Survey questionnaire.

MEASUREMENTS AND MAIN RESULTS

The response rate was 645 (32%) of 2,000 mailed surveys; analysis of data represents completed questionnaires from 605 respondents. Intensivists (42.3%), pulmonologists (22.6%), and surgeons (21.6%) represent the majority of respondents. Altered level of consciousness (67.9%) in the intensive care unit was identified as the predominant predisposing factor for aspiration pneumonia. Sixty-four percent of physicians used sputum specimens, rather than protected specimen brushes or bronchoalveolar lavage, as the diagnostic source of bacterial cultures in cases of suspected aspiration pneumonia. Microbiological assessment of aspiration pneumonia revealed the absence of any predominant pathogen, although Staphylococcus aureus and Pseudomonas aeruginosa were cited in 40.1% of combined responses, whereas anaerobes represented the fifth most prevalent cultured bacteria. In cases of suspected and confirmed aspiration, 51.9% and 77.7% of respondents, respectively, would prescribe an antimicrobial agent in the absence of a definitive infectious process, with administration of dual antimicrobial therapy increasing from 28.9% to 46.0% in suspected vs. confirmed cases of aspiration. In the treatment of aspiration pneumonia, 27.6% of physicians preferred pathogen-specific therapy, whereas the remainder (72.4%) selected an empirical antibiotic regimen based on prior clinical experience. Overall, a beta-lactam/beta-lactamase inhibitor, followed by a cephalosporin, aminoglycoside in combination, or clindamycin, was most often selected for empirical therapy of all defined aspiration-related clinical diagnoses.

CONCLUSIONS

Our study revealed a divergent approach to antimicrobial treatment of cases of aspiration in the intensive care unit. Further investigation is warranted to determine why empirical antimicrobials are initiated frequently for noninfectious stages of aspiration.

Assessing the force generated with application of cricoid pressure

The application of cricoid pressure is a common technique used to decrease the risk of aspiration during anesthetic induction. Research recommends that 3 to 4 kg of cricoid force be applied to achieve effective esophageal occlusion. The purpose of this study was to assess perioperative nurses' knowledge regarding the recommended amount of cricoid force that should be applied to the cricoid cartilage and to assess the amount of force generated when cricoid pressure was applied to a scale-mounted model. A convenience sample of 102 perioperative nurses participated in the study. Five percent of participants identified the correct amount of force necessary. Applied force was significantly less than the recommended amount. Findings of this study suggest perioperative nurses lack both knowledge and clinical skill for generating effective amounts of cricoid force.

Aspiration diseases: findings, pitfalls, and differential diagnosis

The aspiration of different substances into the airways and lungs may cause a variety of pulmonary complications. These disease entities most commonly involve the posterior segment of the upper lobes and the superior segment of the lower lobes. Esophagography and computed tomography (CT) are especially useful in the evaluation of aspiration disease related to tracheoesophageal or tracheopulmonary fistula. Foreign body aspiration typically occurs in children and manifests as obstructive lobar or segmental overinflation or atelectasis. An extensive, patchy bronchopneumonic pattern may be observed in patients following massive aspiration of gastric acid or water. CT is the modality of choice in establishing the diagnosis of exogenous lipoid pneumonia, which can result from aspiration of hydrocarbons or of mineral oil or a related substance. Aspiration of infectious material manifests as necrotizing consolidation and abscess formation. The relatively low diagnostic accuracy of chest radiography in aspiration diseases can be improved with CT and by being familiar with the clinical settings in which specific complications are likely to occur. Recognition of the varied clinical and radiologic manifestations of these disease entities is imperative for prompt, accurate diagnosis, resulting in decreased morbidity and mortality rates.

The inadequacies of contemporary oropharyngeal suction

Airway management is the highest priority in any resuscitation. Suction equipment capable of rapidly clearing the oropharynx is mandatory for airway management. Inadequate oropharyngeal suction with standard equipment may be associated with major complications in emergency airway management. We report cases that illustrate the inadequacies of standard suction equipment. Available oropharyngeal aspirators and their limitations are discussed. Recent advances in the field of oropharyngeal suction also are described.

Causes and complications associated with swallowing disorders in traumatic brain injury

A major complication commonly seen in persons with severe brain injury is swallowing dysfunction. The neuropathology leading to impaired swallowing is discussed. In addition, Other risk factors associated with dysfunctional swallowing, such as tracheostomy and the need for prolonged ventilatory support, are discussed. Within the intensive care environment, the consequences of impaired swallowing leading to aspiration-a major cause of pneumonia-are discussed.

Frequency of videofluoroscopic modified barium swallow studies and pneumonia in stroke rehabilitation patients: a comparative study

OBJECTIVE

To study the association between the frequency of videofluoroscopic modified barium swallow (VMBS) studies and the incidence of pneumonia in stroke rehabilitation patients.

DESIGN

Retrospective comparative study.

SUBJECTS AND SETTING

Five hundred sixty-three consecutive stroke patients admitted to one hospital rehabilitation unit in London, Ontario, Canada were compared with 461 consecutive stroke patients admitted to another hospital rehabilitation unit in the same city.

INTERVENTIONS

The number of initial and total VMBS studies and the timing from stroke onset to initial VMBS studies.

MAIN OUTCOME MEASURE

Incidence of pneumonia.

RESULTS

At the first hospital, 146 patients (25.9%) had 232 total VMBS studies performed, whereas at the second hospital 57 patients (12.4%) had 73 total studies (p<.001). For the first 15 days there was no significant difference in the number of initial VMBS studies performed (8.2% vs. 9.2%). There was a marked difference in the number of initial VMBS studies performed after 15 days (17.2% vs. 2.0%, p<.0001). The difference between the hospitals in the number of VMBS studies in patients with brain stem strokes was not statistically significant, but for patients with hemispheric stroke, the difference was statistically significant. Pneumonia developed in 12 patients at the first hospital (2.1%) and 10 patients at the second hospital (2.2%), a difference that was not significant.

CONCLUSIONS

The more frequent use of VMBS beyond 15 days after stroke was not associated with a change in the incidence of pneumonia among hemispheric stroke rehabilitation patients, assuming the two units were otherwise similar.

FEESST: a new bedside endoscopic test of the motor and sensory components of swallowing

We here introduce an office or bedside method of evaluating both the motor and sensory components of swallowing, called fiberoptic endoscopic evaluation of swallowing with sensory testing (FEESST). FEESST combines the established endoscopic evaluation of swallowing with a technique that determines laryngopharyngeal (LP) sensory discrimination thresholds by endoscopically delivering air pulse stimuli to the mucosa innervated by the superior laryngeal nerve. Endoscopic assessment of LP sensory capacity followed by endoscopic visualization of deglutition was prospectively performed 148 times on 133 patients with dysphagia over an 8-month period. The patients had a variety of underlying diagnoses, with stroke and chronic neurologic disease predominating (n = 94). Subsequent to LP sensory testing, a complete dysphagia evaluation was conducted. Various food and liquid consistencies were dyed green, and attention was paid to their management throughout the pharyngeal stage of swallowing. Evidence of latent swallow initiation, pharyngeal pooling and/or residue, laryngeal penetration, laryngeal aspiration, and/or reflux was noted. Recommendations for therapeutic intervention were based on information obtained during the FEESST and often involved the employment of compensatory swallowing strategies, modification of the diet or its presentation, placement on non-oral feeding status, and/or referral to other related specialists. All patients successfully completed the examination. In 111 of the evaluations (75%), severe (>6.0 mm Hg air pulse pressure [APP]) unilateral or bilateral LP sensory deficits were found. With puree consistencies, 31% of evaluations with severe deficits, compared to 5% of evaluations with either normal sensitivity or moderate (4.0 to 6.0 mm Hg APP) LP sensory deficits, displayed aspiration (p < .001, chi2 test). With puree consistencies, 69% of evaluations with severe deficits, compared to 24% with normal or moderate deficits, displayed laryngeal penetration (p < .001, chi2 test). FEESST allows the clinician to obtain a comprehensive bedside assessment of swallowing that is performed as the initial swallowing evaluation for the patient with dysphagia.

Aspiration-Induced Pulmonary Injury

Pulmonary aspiration of gastric contents can cause a spectrum of sequelae that spans from relatively minor to rapidly lethal disease. To emphasize the extent of this spectrum and to encompass both noninfectious complications and infection, we use the term “aspiration-induced pulmonary injury” rather than “aspiration pneumonia.” In this article we review the relevant literature, focusing on more recent insights into the pathogenesis of lung injury, the natural history of aspiration, risk factors, the relationship between aspiration and infection, and recommendations for management. The relevance to human disease of studies using intra-airway acid instillation in animals is questioned. We discuss the difficulties in predicting the clinical course after aspiration. We identify risk factors for aspiration-induced pulmonary injury that are commonly encountered in the intensive care unit, and discuss in detail factors of special interest to the intensivist, including the impact of tracheal intubation; the effects of enteric intubation, particularly the comparison between pre- and postpyloric routes of enteric feeding administration; and the relative risks associated with particular feeding protocols. We conclude with recommendations regarding treatment and prevention strategies.

Value of C-reactive protein in the detection of bacterial contamination at the time of presentation in drug-induced aspiration pneumonia

STUDY OBJECTIVES

To compare the plasma concentration of C-reactive protein (CRP) with traditional markers for diagnosis of bacterial pneumonia in patients with suspected aspiration.

DESIGN

Prospective, nonrandomized, controlled study of consecutive hospital admissions.

SETTING

Toxicology ICU in a university hospital.

PATIENTS OR PARTICIPANTS

Acutely poisoned comatose patients admitted to the hospital with suspicion of aspiration pneumonia.

INTERVENTIONS

Distal protected catheter sampling per fiberoptic bronchoscopy and bacteriologic culture were employed as a standard to detect the bacterial component of suspected aspiration pneumonia. Plasma CRP concentrations, temperature, and WBC count were measured on hospital day 1.

MEASUREMENTS AND RESULTS

Sixty-six patients were evaluated. Thirty-two had bacterial contamination by positive culture (> or =10(3) cfu/mL). Multiple receiver-operating characteristic (ROC) curves were used to compare each parameter for detection of infection secondary to aspiration. The ROC curve of CRP concentrations showed that a CRP >75 mg/L is associated with bacterial contamination with a sensitivity of 87%, specificity of 76%, positive predictive value of 78%, and negative predictive value of 87%. ROC curves of temperature and WBC count demonstrated poor diagnostic value of these markers in indicating the bacterial component of suspected aspiration pneumonia.

CONCLUSIONS

Early measurement of CRP is useful for the diagnosis of aerobic bacterial content of aspiration pneumonia and perhaps in determining the need for invasive bacteriologic sampling. Temperature and WBC count are poor indicators of bacterial infection of aspiration pneumonia in poisoned patients.

Silent laryngopharyngeal sensory deficits after stroke

Dysphagia and aspiration are two devastating sequelae of stroke. Recent work has shown that laryngopharyngeal (LP) sensory deficits are associated with aspiration in stroke patients with dysphagia. The phenomenon of silent LP sensory deficits, where the patient exhibits no subjective or objective evidence of dysphagia, yet has an LP sensory deficit, has not been previously described. The aim of this study was to evaluate the sensory capacity of the laryngopharynx in stroke patients who had no subjective or objective complaints of dysphagia. We determined the sensory threshold in the laryngopharynx using air pulse stimulation of the mucosa of the pyriform sinus and aryepiglottic fold. Eighteen stroke patients (mean age 65.6 +/- 11.5 years) and 18 age-matched controls were prospectively evaluated. Normal thresholds were defined as < 4.0 mm Hg air pulse pressure (APP). Deficits were defined as either a moderate impairment in sensory discrimination thresholds (4.0 to 6.0 mm Hg APP) or a severe sensory impairment (> 6.0 mm Hg APP). Stroke patients were followed up for 1 year to determine the incidence of aspiration pneumonia (AP) as verified by chest radiography. In 11 of the stroke patients studied, either unilateral (n = 6) or bilateral (n = 5) severe sensory deficits were identified. The elevations in sensory discrimination thresholds were significantly greater than those in age-matched controls (7.1 +/- 0.6 mm Hg APP versus 2.5 mm Hg APP; p < .01, Wilcoxon score). Among patients with unilateral deficits, sensory thresholds were severely elevated in all cases on the affected side compared with the unaffected side (p < .01, Wilcoxon score). Moreover, the sensory thresholds of the unaffected side were not significantly different from those of age-matched controls. Aspiration pneumonia did not occur in the patients with normal LP sensation or in the patients with unilateral severe LP sensory deficits. However, in the 5 patients with bilateral, severe LP sensory deficits, 2 developed AP, both within 3 months of their LP sensory test. The results of this study showed, for the first time, that stroke patients without subjective or objective clinical evidence of dysphagia could have silent LP sensory deficits. These impairments could contribute to the development of AP following stroke. The findings in this study suggest that LP sensory discrimination threshold testing should not be restricted only to patients with clinical dysphagia.

Detection of pulmonary aspiration of gastric contents in an animal model by assay of peptic activity in bronchoalveolar fluid

OBJECTIVE

To determine whether peptic activity in bronchoalveolar fluid, due to the presence of the gastric proteolytic enzyme pepsin, could serve as a biochemical marker for pulmonary aspiration of gastric contents.

DESIGN

Prospective, experimental trial.

SETTING

A university animal research laboratory.

SUBJECTS

Thirty-six New Zealand rabbits, weighing 2 to 4 kg.

INTERVENTIONS

New Zealand rabbits were anesthetized, intubated via tracheostomy, and mechanically ventilated. Pulmonary aspiration was induced by the intratracheal instillation of 2 mL/kg human gastric juice (pH 1.2 +/- 0.2; pepsin activity 0.02 +/- 0.006 microgram/mL; human gastric juice group, n = 24) or normal saline solution (pH 5.2 +/- 0.2; normal saline solution group; n = 12). Mechanical ventilation was continued. Bronchoalveolar lavage was performed at 15 mins (human gastric juice group, n = 8; normal saline solution group, n = 4), 30 mins (human gastric juice group, n = 8; normal saline solution group, n = 4), or 60 mins (human gastric juice group, n = 8; normal saline solution group, n = 4) postaspiration.

MEASUREMENTS AND MAIN RESULTS

Peak airway pressure and PaO2 values were measured at baseline and 15 and 30 mins after aspiration. The pH of retrieved bronchoalveolar lavage fluid was measured and pepsin activity in sample fluid was determined. Changes from baseline in peak airway pressure and PaO2 were significant in human gastric juice animals at 15 and 30 mins when compared with normal saline solution animals (PaO2 -4% vs. -44%, peak airway pressure 20% vs. 36% at 15 mins; PaO2 -16% vs. -79%, peak airway pressure 28% vs. 69% at 30 mins; normal saline solution group vs. human gastric juice group, p < .02). Bronchoalveolar lavage fluid pH was not significantly different between groups at any time postaspiration (6.6 +/- 0.7 vs. 6.0 +/- 0.4 at 15 mins; 7.4 +/- 0.9 vs. 6.5 +/- 0.4 at 30 mins; 7.2 +/- 0.5 vs. 6.4 +/- 0.4 at 60 mins, normal saline solution group vs. human gastric juice group, p = NS). No peptic activity was present in bronchoalveolar lavage fluid from normal saline solution animals at any time. In the human gastric juice group, peptic activity was detected in postaspiration bronchoalveolar lavage fluid in eight of eight animals at 15 mins, six of eight animals at 30 mins, and five of eight animals at 60 mins (normal saline solution group vs. human gastric juice group; p < .001 at 15 mins, p < .01 at 30 mins, p = NS at 60 mins). Peptic activity of bronchoalveolar lavage fluid varied; mean values were greater at 15 mins than at 30 or 60 mins (pepsin activity: 0.004 +/- 0.002 microgram/mL vs. 0.002 +/- 0.001 microgram/mL vs. 0.0006 +/- 0.0001 microgram/mL, respectively, p < .05).

CONCLUSIONS

The results of this study suggest that peptic activity in bronchoalveolar lavage fluid can be detected up to 60 mins after induced, experimental gastric juice aspiration and may prove a clinically useful biochemical marker for episodes of occult pulmonary aspiration of gastric contents.

Pneumonia associated with aspiration following stroke

OBJECTIVE

To determine the association between demonstrated aspiration and pneumonia in stroke patients.

METHODS

Chart review of 441 consecutive stroke patients admitted to a stroke rehabilitation unit within 4 months of their stroke over an 8-year period. Videofluoroscopic modified barium swallow (VMBS) was performed on all patients suspected of aspirating. In all patients, the presence or absence of pneumonia was noted.

RESULTS

Eighty-four of the 441 (19.0%) stroke patients transferred for rehabilitation demonstrated aspiration of thin liquids on VMBS. Twelve of the 441 (2.7%) developed pneumonia while in hospital, either in the acute or rehabilitation phases. The incidence of pneumonia among proven aspirators on VMBS was 10 of 84 (11.9%) patients. Two of the 357 (0.6%) patients who were presumed nonaspirators developed pneumonia. Brain stem and right hemispheric stroke patients had a higher incidence of pneumonia.

CONCLUSIONS

Pneumonia is an uncommon complication of stroke. However, approximately 12% of stroke rehabilitation patients diagnosed as aspirators on VMBS developed pneumonia, a 20-fold increase over presumed nonaspirators. VMBS is a potentially valuable tool in determining those patients at risk of aspiration pneumonia.

Hypotension induced by haemorrhage impairs lower oesophageal sphincter function

The effect of haemorrhage-induced hypotension on lower oesophageal sphincter (LOS) tone was studied in 11 adult mongrel dogs. Mean(s.e.m.) blood loss of 760(66) ml, corresponding to 42 per cent of estimated blood volume, was associated with a significant fall in LOS tone (14.2(1.0) versus 7.2(0.6) sphinctometer units, P < 0.002). This was associated with a reduction in mean(s.e.m.) arterial blood pressure (99(7) versus 53(3) mmHg, P < 0.002) and heart rate (113(6) versus 106(5) beats per min, P = 0.06). Group 1 animals (n = 6) received autotransfusion, restoring LOS tone to prehaemorrhage values. Dogs in group 2 (n = 5) were given intravenous erythromycin 4 mg/kg, which also restored LOS tone. This effect was transient, lasting a mean(s.e.m.) of only 67(7) min. Infusion of an equivalent volume of 0.9 per cent saline following cessation of the erythromycin effect restored LOS tone to control values although the animals remained hypotensive. Reduction in LOS tone with haemorrhage may be part of a vagal reflex mediated by myocardial afferent C fibres and may explain the high incidence of pulmonary aspiration in shocked patients.

Is penicillin G an adequate initial treatment for aspiration pneumonia? A prospective evaluation using a protected specimen brush and quantitative cultures

OBJECTIVE

To evaluate the bacteriology of early aspiration pneumonia using a protected specimen brush and quantitative culture techniques, and whether penicillin G is adequate as initial treatment pending culture results.

PATIENTS AND METHODS

52 patients (of which 45 required mechanical ventilation) meeting usual clinical criteria for aspiration pneumonia were prospectively included. On admission, patients were given intravenous penicillin G and a protected specimen brush was performed < or = 48 h after.

RESULTS

Cultures of the brush were negative (< 10(3) CFU/ml) in 33 patients (1 had blood cultures positive with S. pneumoniae) and positive (> or = 10(3) CFU/ml) for S. pneumoniae in 2 patients. Seventeen patients had a positive culture (> or = 10(3) CFU/ml) for at least one penicillin G resistant microorganism, with a total of 20 organisms (S. aureus: 6; H. influenzae: 2; Enterobacteriaceae: 8; P. aeruginosa: 3; C. albicans: 1). In 4 of these patients, a penicillin-sensitive pathogen was also recovered in significant concentrations (S. pneumoniae: 2; Streptococcus sp.: 2). These 17 patients with a resistant pathogen did not differ from the 35 other patients with respect to need for ventilatory support and mortality rate. By contrast, they were older (61.1 +/- 21.9 vs. 42.9 +/- 18.8 years; p < 0.005) and required longer mechanical ventilation (6.1 +/- 4.6 vs. 3.5 +/- 2.7 days; p < 0.03) and hospitalization (11.2 +/- 8.8 vs. 6.7 +/- 4.7 days; p < 0.02). Of 17 patients 12 with penicillin G resistant organisms versus 0/35 without, were in-hospital patients and/or had a digestive disorder (p < 0.001).

CONCLUSION

The broad range of offending organisms seen in early aspiration pneumonia precludes use of any single empiric regimen, making protected specimen brush mandatory in many patients. Nevertheless, the involvement of S.pneumoniae in a notable proportion of our patients suggests that routine penicillin prophylaxis after early aspiration (at least in most patients with community-acquired aspiration) is warranted given the potential severity of pneumococcal sepsis in such patients.