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PubMed2007

Routine evaluation for aspiration after thoracotomy for pulmonary resection.

BACKGROUND: The purpose of this study was to evaluate the role of a routine protocol for evaluation of oropharyngeal aspiration after thoracotomy for pulmonary resection. METHODS: Demographic, operative, and outcomes data were collected prospectively for consecutive patients undergoing thoracotomy for pulmonary resection starting in April 2005. Starting on postoperative day one, patients underwent evaluation by a licensed speech therapist before per os intake. Patients failing clinical examination were referred for radiographic evaluation. Diets were advanced on the basis of results from both clinical and radiographic evaluation. Data analysis included descriptive statistics, Student's t test, and chi2 test when appropriate. RESULTS: One hundred forty patients were prospectively evaluated during this period. Thirty-two patients (22.9%) failed initial clinical swallowing evaluation and were referred for dynamic videofluoroscopic esophagram. Twenty-five patients (17.8%) had evidence of potential oropharyngeal aspiration on videofluoroscopic esophagram. Only 1 patient (0.7%) aspirated after a negative clinical evaluation. Univariate risk factor analysis revealed that patients demonstrating aspiration were older (67.7 +/- 1.6 years versus 64.4 +/- 1.1 years; p = 0.10) and had a higher incidence of head and neck malignancy (p < 0.001). Patients without radiographic aspiration had a shorter median hospital stay when compared with those who did (6 days versus 5 days). CONCLUSIONS: Aspiration after thoracotomy for pulmonary resection may affect nearly 20% of patients and is likely underrepresented in the surgical literature. The institution of a protocol to evaluate risk of aspiration has characterized patients at high risk and led to an increased awareness of the potential for aspiration after thoracotomy.

Adolescent↗

PubMed2003

Racial disparity in meconium-stained amniotic fluid and meconium aspiration syndrome in the United States, 1989-2000.

OBJECTIVE: To estimate the prevalence of meconium-stained amniotic fluid and meconium aspiration syndrome, as well as the differences in case fatality from meconium aspiration syndrome, between non-Hispanic black and non-Hispanic white infants. METHODS: We studied non-Hispanic black and non-Hispanic white live births with weights greater than 2.5 kg and gestational ages greater than 35 weeks, using the linked US birth and infant death cohorts for three periods: 1989-1991, 1995-1997, and 1998-2000. We used logistic regression to estimate the risks of meconium-stained amniotic fluid and meconium aspiration syndrome and to estimate the case fatality of meconium aspiration syndrome by maternal race, birth weight, period, and pregnancy complications. RESULTS: Risk of meconium-stained amniotic fluid was 80% higher in non-Hispanic blacks when compared with non-Hispanic whites (birth weight-adjusted odds ratio [OR], 1.81, 95% confidence interval [CI] 1.80, 1.82). The prevalence of pregnancy complications did not explain this racial disparity. Risk of meconium aspiration syndrome in non-Hispanic blacks was 67% higher when compared with non-Hispanic whites (birth weight-adjusted OR 1.67, 95% CI 1.64, 1.70). The case fatality rate of meconium aspiration syndrome was similar between non-Hispanic blacks and non-Hispanic whites in the three periods, with rates of 15.5, 15.2, and 11.2 per 1000 in non-Hispanic blacks and 13.5, 11.2, and 10.1 per 1000 in non-Hispanic whites in 1989-1991, 1995-1997, and 1998-2000, respectively. CONCLUSION: Our results suggest that when compared with non-Hispanic whites, non-Hispanic blacks are at significantly greater risk for meconium-stained amniotic fluid and meconium aspiration syndrome but not for meconium aspiration syndrome case fatality.

Amniotic Fluid↗

PubMed2006

Aspiration rate following chemoradiation for head and neck cancer: an underreported occurrence.

BACKGROUND AND PURPOSE: We would like to assess the prevalence of aspiration before and following chemoradiation for head and neck cancer. PATIENTS AND METHODS: We reviewed retrospectively the Modified Barium Swallow (MBS) in 63 patients who underwent concurrent chemotherapy and radiation for head and neck cancer. MBS was performed prior to treatment to determine the need for immediate gastrostomy tube placement. MBS was repeated following treatment to assess the safety of oral feeding prior to removal of tube feeding. All patients were cancer free at the time of the swallowing study. No patient had surgery. Dysphagia severity was graded on a scale of 1-7. Tube feedings were continued if patients were diagnosed to have severe aspiration (grade 6-7) or continued weight loss. Patients with abnormal swallow (grade 3-7) received swallowing therapy following MBS. RESULTS: Before treatment, there were 18 grade 1, 18 grade 2, 9 grade 3, 8 grade 4, 3 grade 5, 3 grade 6, and 4 grade 7. Following chemoradiation, at a median follow-up of 2 months (1-10 months), one patient had grade 1, eight patients had grade 2, nine patients had grade 3, eight patients had grade 4, 13 patients had grade 5, seven patients had grade 6, and 11 patients had grade 7. Six patients died from aspiration pneumonia (one before, three during, and two post-treatment), and did not have the second MBS. Overall, 37/63 (59%) patients developed aspiration, six of them (9%) fatal. If we excluded the 10 patients who had severe aspiration at diagnosis and the six patients who died from pneumonia, the prevalence of severe aspiration was 33% (21/63). CONCLUSIONS: Aspiration remained a significant morbidity following chemoradiation for head and neck cancer. Its prevalence is underreported in the literature because of its often silent nature. Diagnostic studies such as MBS should be part of future head and neck cancer prospective studies to assess the prevalence of aspiration, and for rehabilitation.

Aged↗

PubMed1992

Percutaneous endoscopic gastrostomy or jejunostomy and the incidence of aspiration in 79 patients.

Percutaneous endoscopic gastrostomy (PEG) and percutaneous endoscopic jejunostomy (PEJ) are well-accepted procedures for long-term enteral alimentation. PEG has replaced surgical gastrostomy at many institutions because of its safety and ease. This study was undertaken to evaluate the indications for PEG and PEJ, as well as their success rates, complications with special attention to aspiration, and long-term follow-up. We were specifically interested in reviewing the problem of aspiration in patients with PEG and PEJ. A retrospective review of 79 patients at Brooke Army Medical Center over a 3-year period was done. PEG or PEJ was successful in 79 of 81 patients (97%). The most common indications were neurologic disorders in 46 patients (58%) and cancer in 20 (25.3%). Complications other than aspiration occurred in 11 patients (14%). Aspiration occurred in nine patients after PEG or PEJ (11.4%); six patients had experienced aspiration prior to PEG or PEJ. Six patients had a jejunostomy tube placed through the PEG for prevention of aspiration, and three died of continued aspiration. We conclude that aspiration is not prevented by PEJ, continues to be a major problem after PEJ, and becomes manifest for the first time after PEG.

Adolescent↗

PubMed2001

Nucleated red blood cells in meconium aspiration syndrome.

OBJECTIVE: To evaluate whether the absolute nucleated red blood cell (RBC) count is higher in infants who had meconium aspiration with respiratory symptoms compared with infants with asymptomatic meconium aspiration and controls. METHODS: We compared the absolute nucleated RBC counts during the first 12 hours of life in three groups of term, vaginally delivered infants, including those who had meconium aspiration with respiratory symptoms (n = 11), asymptomatic meconium aspiration (n = 45), and control healthy infants (n = 32). We excluded infants of women with diabetes in pregnancy; hypertension; alcohol, tobacco, or drug abuse; and those with hemolysis, blood loss, or chromosomal anomalies. RESULTS: There were no significant differences among groups in gestational age; gravidity; parity; maternal analgesia; lymphocyte, platelet, and granulocyte counts; and hematocrit. The median nucleated RBC count was significantly higher in the meconium aspiration group with respiratory symptoms (0.007 x 10(9)/L) than the asymptomatic meconium aspiration group (0.004 x 10(9)/L) or controls (0.003 x 10(9)/L). CONCLUSION: At birth, infants with meconium aspiration syndrome had higher absolute nucleated RBC counts compared with infants with asymptomatic meconium aspiration and normal infants.

Adult↗

PubMed1995

Neutrophil adhesion receptor CD18 mediates remote but not localized acid aspiration injury.

BACKGROUND: Acid aspiration leads to lung polymorphonuclear neutrophil (PMN) sequestration and an associated increase in permeability. Although it is known that the neutrophil adhesion receptor (CD18) plays no role in determining PMN accumulations in the region aspirated, we postulated that this PMN adhesion receptor and its endothelial ligand, intercellular adhesion molecule-1 (ICAM-1), mediate remote neutrophil sequestration. METHODS: Anesthetized rabbits underwent localized aspiration of either 0.1N HCl 0.1 ml/kg (n = 18) or saline solution (n = 18). RESULTS: After 30 minutes leukopenia was noted, 2290 +/- 200 white blood cells/mm3 (p < 0.05). At 3 hours diapedesis occurred in the aspirated segment with accumulations in bronchoalveolar lavage fluid (X10(4)) of 87 +/- 6 PMN/ml versus control of 6 +/- 1 PMN/ml (p < 0.05). Histologic evidence of generalized lung leukosequestration occurred. The wet to dry weight ratio of the nonaspirated lung rose to 5.7 +/- 0.2 versus control of 3.9 +/- 0.1 (p < 0.05). Treatment (n = 18) with the CD18 monoclonal antibody (mAb) (R15.7, 1 mg/kg) had no effect on neutrophil accumulations in the aspirated segment. However, the mAb attenuated the remote inflammatory response: early leukopenia (5790 +/- 400 white blood cells/mm3); lung leukosequestration (24 +/- 4 PMN/10 high-power fields); protein leak in bronchoalveolar lavage fluid (570 +/- 50 micrograms/ml); and edema, wet to dry weight ratio (4.9 +/- 0.1) (all p < 0.05). Treatment with the ICAM-1 mAb (RR1/1, 1 mg/kg) (n = 9) did not reduce neutrophil accumulations in the aspirated segment but limited the remote inflammatory response. CONCLUSIONS: Acid aspiration leads to neutrophil adhesion and edema in regions remote from those aspirated via neutrophil CD18 and endothelial ICAM-1.

Animals↗

PubMed1997

The use of the salivagram in the evaluation of severe and chronic aspiration.

Chronic salivary aspiration may be responsible for a significant percentage of pneumonia in the neurologically impaired child. The radionuclide salivagram (RS), a simple investigative study, can document salivary aspiration as the source of pulmonary contamination. The purpose of this study was to determine if the results of the RS would accurately identify children with severe and chronic salivary aspiration who would benefit from laryngotracheal separation (LTS). We reviewed 30 records of children with chronic aspiration pneumonitis who underwent LTS between 1988 and 1996. We recorded the number of inpatient days required for respiratory infections before and after LTS. This number was compared with the number of inpatient days for respiratory infection from children (n = 27) who underwent the RS during a ten-month period but who were never referred for LTS. Fifteen children who underwent LTS had a preoperative RS. The RS documented salivary aspiration in 11 of these children. Aspiration was effectively controlled by LTS for this group. There were three studies that failed to show either aspiration or progression of the Technetium 99m sulfur colloid (Tc 99m SC) into the esophagus This finding was felt to represent significant swallowing dysfunction and, therefore, was also considered a positive finding. There was a significant difference in the number of inpatient days for children who had a negative RS and were never referred for LTS when compared with the number of inpatient days for those children who had a positive RS and were referred for LTS. We feel that the RS is an effective tool to document salivary aspiration as the source of recurrent pneumonia. A modification of the technique and interpretation of RS is suggested.

Child↗

PubMedDate not supplied

Intratracheal long-term pH monitoring: a new method to evaluate episodes of silent acid aspiration in patients after esophagectomy and gastric pull up.

Aspiration of gastric contents is considered a leading cause of postoperative pulmonary complications after esophagectomy and gastric pull up but has been difficult to diagnose. We used intratracheal long-term pH monitoring to evaluate the prevalence of aspiration of gastric contents in patients undergoing these operations. Continuous intratracheal pH monitoring was carried out during the first 72 postoperative hours in 16 patients with esophageal carcinoma who had undergone esophagectomy and gastric pull up. A drop in the pH to less than 4 was defined as an episode of acid aspiration. All patients except one tolerated the probe without any difficulties. Episodes of acid aspiration could be detected in 12 (80%) of 15 patients (5 of 8 after transhiatal esophagectomy, 7 of 7 after transthoracic esophagectomy, 2 of 5 with reconstruction in the anterior mediastinum, and 9 of 10 with reconstruction in the posterior mediastinum). The number of aspiration episodes was significantly higher during postoperative day 1 (P=0.03) compared to postoperative days 2 and 3. Two patients developed pneumonia later in the postoperative course. Both of them had several episodes of acid aspiration detected by pH monitoring immediately postoperatively. Intratracheal pH monitoring is a safe, feasible, and well-tolerated method for detecting episodes of acid aspiration after esophagectomy and gastric pull up. Aspiration of gastric contents is a common phenomenon particularly during the first 24 postoperative hours after transthoracic esophagectomy and gastric pull up in the posterior mediastinum and appears to correlate with the development of postoperative pneumonia.

Adenocarcinoma↗

PubMed2004

Longitudinal relationships among overweight, life satisfaction, and aspirations in young women.

OBJECTIVE: This study investigated associations of overweight status and changes in overweight status over time with life satisfaction and future aspirations among a community sample of young women. RESEARCH METHODS AND PROCEDURES: A total of 7865 young women, initially 18 to 23 years of age, completed two surveys that were 4 years apart. These women provided data on their future life aspirations in the areas of further education, work/career, marital status, and children, as well as their satisfaction with achievements to date in a number of life domains. Women reported their height and weight and their sociodemographic characteristics, including current socioeconomic status (occupation). RESULTS: Young women's aspirations were cross-sectionally related to BMI category, such that obese women were less likely to aspire to further education, although this relationship seemed explained largely by current occupation. Even after adjusting for current occupation, young women who were obese were more dissatisfied with work/career/study, family relationships, partner relationships, and social activities. Weight status was also longitudinally associated with aspirations and life satisfaction. Women who were overweight or obese at both surveys were more likely than other women to aspire to "other" types of employment (including self-employed and unpaid work in the home) as opposed to full-time employment. They were also less likely to be satisfied with study or partner relationships. Women who resolved their overweight/obesity status were more likely to aspire to being childless than other women. DISCUSSION: These results suggest that being overweight/obese may have a lasting effect on young women's life satisfaction and their future life aspirations.

Adolescent↗

PubMed1999

Aspiration during anaesthesia: a review of 133 cases from the Australian Anaesthetic Incident Monitoring Study (AIMS).

Two-hundred and forty incidents of vomiting/regurgitation and aspiration were reported to the Anaesthetic Incident Monitoring Study database consisting of 5000 reports. Of these, 133 cases of aspiration were recorded. Passive regurgitation occurred three times more commonly than active vomiting. Aspiration was reported twice as often in elective compared with emergency surgery, with 56% of incidents taking place during induction of anaesthesia. Anti-aspiration prophylaxis was prescribed in 14% of patients who subsequently aspirated; however, the majority of cases had at least one predisposing factor for regurgitation, vomiting or aspiration evident peri-operatively. While a major immediate physiological disturbance was common, long-term morbidity was not. Death ensued in five cases, all of whom had significant co-morbidities. Factors reported as contributing to the incident included error of judgement and fault of technique, while clinical experience and anaesthetic assistance tended to minimise the incident. Aspiration remains an important anaesthetic-related morbidity. The application of simple guidelines may have prevented the incident in 60% of all cases of aspiration. Ensuring airway security may be as important as chemoprophylaxis in its prevention.

Adolescent↗

PubMed2005

Aspiration pneumonitis primes the host for an exaggerated inflammatory response during pneumonia.

OBJECTIVE: Nosocomial pneumonia is a feared complication in the critically ill patient. Aspiration pneumonitis is frequently complicated by infections. The objective of this study was to determine the influence of aspiration pneumonitis on the host response to a common nosocomial respiratory pathogen. DESIGN: Controlled, in vivo laboratory study. SETTING: Research laboratory of a health sciences university. SUBJECTS: Female C57Bl/6 mice. INTERVENTIONS: Mice received hydrochloric acid or saline intratracheally followed 16 hrs later by Klebsiella pneumoniae. MEASUREMENTS AND MAIN RESULTS: Hydrochloric acid induced a mild aspiration pneumonitis. Nonetheless, hydrochloric acid aspiration resulted in a markedly increased inflammatory response in the lung on infection with K. pneumoniae. This enhanced inflammatory reaction was accompanied by a greatly increased outgrowth of K. pneumoniae in lungs of mice previously exposed to hydrochloric acid. Preexisting aspiration pneumonitis also triggered mouse lungs in vivo and alveolar macrophages ex vivo for enhanced release of proinflammatory mediators on stimulation with Klebsiella lipopolysaccharide. Inhibition of tumor necrosis factor-alpha resulted in an increased inflammatory reaction and enhanced bacterial outgrowth in mice with primary K. pneumoniae pneumonia, whereas it had no effect in mice with preexisting aspiration pneumonitis. CONCLUSIONS: These data indicate a) that aspiration pneumonitis renders the host more susceptible to respiratory tract infection with K. pneumoniae, concurrently priming the lung for an exaggerated inflammatory response; and b) that although tumor necrosis factor-alpha plays a major role in the host response to primary infection, it does not affect lung inflammation or defense after aspiration pneumonitis.

Analysis of Variance↗

PubMed1996

Aspiration in transtracheal jet ventilation.

BACKGROUND: Transtracheal jet ventilation (TJV) has been used successfully for managing difficult airways. However, there are some controversies regarding pulmonary aspiration. It has been shown that TJV caused no aspiration as long as the frequency of ventilation was kept higher than 60/ min. On the other hand, it has been demonstrated that manual translaryngeal jet ventilation at 20 breaths per minute also provided good protection from aspiration even with 30-degree head-up position. The purpose of this study was to reevaluate this controversy with observation of the trachea and the lungs together during TJV. METHODS: Eight mongrel dogs were anesthetized, paralyzed and ventilated transtracheally with jet ventilator at frequencies variying from 600 to 10/min. The airway pressures below and above the jetting port were measured. The mouth of the dog was then filled with barium and chest x-rays were taken 5 minutes after each different jetting frequency. RESULTS: No tracheal or pulmonary aspiration was observed on chest x-rays as long as the frequencies were set above 80 per minute. With frequencies of 60 per minute, barium was seen in the trachea but at a level above the jetting port. Slowing down the frequency to 10/min did not affect the level of barium. CONCLUSION: No aspiration could be visualized on chest x-rays. The mechanism for preventing pulmonary aspiration is thought to be due to forceful continuous gas outflow through the larynx. The epiglottis seems to play no role in this mechanism. The limited tracheal aspiration was probably due to the existence of a negative pressure in the upper airway. Cessation of the TJV will cause a drop in this pressure gradient and results in pulmonary aspiration. It is recommended that the airway above the jetting port be totally cleansed prior to discontinuation of the tanstracheal jet ventilation.

Animals↗

PubMed1997

The value of the lipid-laden macrophage index in the assessment of aspiration pneumonia.

BACKGROUND: A semi-quantitative index of lipid-laden macrophages on broncho-alveolar lavage (BAL) has been reported to be highly sensitive but only moderately specific for aspiration in adults. There has been little published literature evaluating this technique since the original report. AIMS: To assess the value of a lipid-laden macrophage index (LLMI) of greater than 100 to confirm the clinical diagnosis of aspiration in patients with abnormal radiological investigations. METHODS: Prospective evaluation of 80 adult patients with abnormal radiology was undertaken using BAL and the LLMI. A diagnosis of aspiration was made prior to bronchoscopy if the patient had one or more of: clinically witnessed aspiration, positive barium swallow or speech pathology assessment; or an upper gastrointestinal endoscopy showed severe reflux oesophagitis and the patient had a history consistent with aspiration. RESULTS: Eighteen patients were diagnosed with aspiration. Of these, 17 had an index > 100, and one had an index of 94 (mean 157, 99% CI 127-187, range 94-238). Of the other 62 subjects, seven had an index > 100 (mean 46, 99% CI 22-70, range 0-303). There was a significant difference between index scores for the two groups (p = 0.002). For aspiration, an index > 100 had a sensitivity of 94% and a negative predictive value of 98%. The specificity was 89%, with a positive predictive value of 71%. CONCLUSIONS: The LLMI is a sensitive indicator for aspiration causing radiological lung disease in adults. Its lack of specificity means it cannot be the sole means of diagnosis, but it can allow better targeting of other investigations in those patients in whom bronchoscopy is undertaken to investigate radiological abnormalities.

Adult↗

PubMed2006

Differences in the features of aspiration pneumonia according to site of acquisition: community or continuing care facility.

OBJECTIVES: To determine the prevalence of aspiration pneumonia and to compare the features and risk factors for this entity in patients from continuing care facilities (CCFs) and the community who were admitted to the hospital with pneumonia. DESIGN: Prospective population-based study. SETTING: Six hospitals in Capital Health Region (Edmonton), Alberta, Canada. PARTICIPANTS: One thousand nine hundred forty-six adults admitted with pneumonia. Patients were stratified by their residence as community or CCF. MEASUREMENTS: Aspiration pneumonia prevalence; risk factors; and outcomes such as mortality, length of stay, and intensive care unit admission rates. RESULTS: Ten percent of those with community-acquired pneumonia (CAP) had aspirated, compared with 30% of those with CCF-acquired pneumonia. Those with community-acquired aspiration pneumonia (CAAP) and those with CCF-acquired aspiration pneumonia (CCF-AP) were younger, more likely to go to ICU, and more likely to require mechanical ventilation and had a longer length of stay and a higher mortality rate than nonaspirators. The risk factors for aspiration differed; for those with CAAP, impaired consciousness due to alcohol, drugs, or hepatic failure predominated, whereas 72% of those with CCF-AP had neurological disease that resulted in dysphagia. Eighty percent were treated with antibiotics effective against anaerobic bacteria. CONCLUSION: Aspiration pneumonia is common in patients with both CAP and CCF-acquired pneumonia. The risk factors differ, and there is a high mortality rate. Neurological disease dominates as the predisposing factor toward aspiration pneumonia in people in CCFs.

Aged↗

PubMed2006

Can pulse oximetry or a bedside swallowing assessment be used to detect aspiration after stroke?

BACKGROUND AND PURPOSE: Desaturation during swallowing may help to identify aspiration in stroke patients. This study investigated pulse oximetry, bedside swallowing assessment (BSA), and videofluoroscopy as tests for detecting aspiration after stroke. METHODS: Swallowing was assessed in 189 stroke patients (mean+/-SD age, 70.9+/-12.3 years) within 5 days of symptom onset with a modified BSA (water replaced by radio-opaque contrast agent, followed by chest radiography to detect aspiration). Simultaneous pulse oximetry recorded the greatest desaturation from baseline for 10 minutes from modified BSA onset. Videofluoroscopy was undertaken in 54 (28%) patients. RESULTS: Modified BSA showed a safe swallow in 98 (51.9%), unsafe swallow in 85 (45.0%), and silent aspiration in 6 (3.2%) patients. During swallowing, desaturation by >2% occurred in 27 (27.6%) and by >5% in 3 (3.1%) of the 98 safe-swallow patients on modified BSA. Of the 85 unsafe-swallow patients, only 28 (32.9%) desaturated by >2% and 6 (7.1%) by >5%. Desaturation did not occur in any of the 6 silent aspirators. With the modified BSA to detect aspiration, sensitivity and specificity, respectively, were 0.31 and 0.72 for desaturation >2% and 0.07 and 0.97 for desaturation >5%. By videofluoroscopy, sensitivity and specificity for detecting aspiration were 0.47 and 0.72 for modified BSA, 0.33 and 0.62 for desaturation >2%, and 0.13 and 0.95 for desaturation >5%. Combining a failed modified BSA with desaturation >2% or >5% did not significantly improve predictive values. CONCLUSIONS: Modified BSA and pulse oximetry during swallowing, whether alone or in combination, showed inadequate sensitivity, specificity, and predictive values for detection of aspiration compared with videofluoroscopy in stroke patients.

Aged↗

PubMed1979

Alveolar-capillary membrane permeability. Correlation with functional, radiographic, and postmortem changes after fluid aspiration.

An index of permeability of the alveolar-capillary membrane was derived from the relative extraction from the lung into arterial blood of 2 tracers, 125I-antipyrine and 51Cr-ethylenediaminetetraacetate. The effect on this index of aspirating 2 ml of isotonic saline, distilled water, or 10(-1) M hydrochloric acid per kg of body weight was studied in 3 groups of rabbits. The severity and time course of changes in the permeability index were correlated with changes in lung mechanics, gas exchange, serial chest roentgenograms, ratio of extravascular lung water to dry weight, and histologic findings. Aspiration of saline produced no change in the permeability index; aspiration of water produced a large mean +/- SEM increase in the index, from a baseline of 0.025 +/- 0.002 to 1,050 +/- 0.054 (P less than 0.001), but this value returned to baseline 15 min later. After hydrochloric acid, the permeability index increased from a baseline of 0.027 +/- 0.003 to 1.068 +/- 0.098 (P less than 0.005), with no evidence of resolution after 60 min. Changes in lung mechanics, gas exchange, and roentgenograms were smallest after aspiration of distilled water and greatest after aspiration of hydrochloric acid. The functional changes after aspiration of water and saline recovered at a rate proportional to the known clearance rates of these liquids from the lung. The changes after hydrochloric acid either showed no tendency toward recovery or, in the case of the roentgenograms, worsened with time. There were no detectable histologic abnormalities or an increase in the ratio of extravascular lung water to dry weight after aspiration of water or saline, but there were extensive histologic abnormalities and a 70 per cent increase in lung water after acid. The increase in the permeability index after aspiration of water was too transient to exert a deleterious effect. In contrast, the persistence of the increase in the permeability index after hydrochloric acid was associated with persistent functional changes attributable to the considerable increase in lung water.

Animals↗

PubMed2003

The incidence and immediate respiratory consequences of pulmonary aspiration of enteral feed as detected using a modified glucose oxidase test.

Pulmonary micro-aspiration of enteral feed in intubated critically ill patients has been reported to occur commonly. In this prospective observational study the incidence of micro-aspiration, diagnosed by a modified glucose oxidase test, is reported in 25 enterally fed critically ill and tracheally intubated patients on a general intensive care unit. Episodes of microaspiration were correlated with changes in PaO2/FiO2 ratio as an index of changes in degree of lung injury. The modified glucose oxidase test differs from the traditional glucose oxidase test because of the enrichment of the feed with glucose (10 g glucose added to 500 ml enteral feed resulting in a tenfold increase in glucose concentration). Pulmonary aspiration of feed was detected by exposing a glucose oxidase strip to tracheal secretions. The feed was enriched with glucose to improve the ability of the reagent strip to detect the feed. The incidence of aspiration of feed was 44% with a prevalence of 6.9% per day of intubation. Only 43% of these episodes of aspiration were detected by the feed being seen in the tracheal secretions. Aspiration was associated with a mean fall in the PaO2/FiO2 ratio of 5.6 kPa from 27.1 kPa to 21.5 kPa (P = 0.002). Aspiration of enteral feed is common and causes a demonstrable morbidity. Detection using this simple bedside test may alert the clinician to institute measures to minimize further aspiration.

Enteral Nutrition↗

PubMed1988

Evaluation of technetium pertechnetate as a radionuclide marker of pulmonary aspiration of gastric contents in rabbits.

At present, there is no sensitive and specific test to confirm the clinical impression that a respiratory disorder is due to aspiration of gastric contents. Since intravenous technetium pertechnetate (99mTcO4-) has been shown to be safe, actively concentrated in the gastrointestinal tract, and secreted into gastric juice, we sought to determine whether 99mTcO4-, when given intravenously, is suitable to detect pulmonary aspiration of small amounts of gastric contents in rabbits. Biodistribution studies over 24 h revealed that 99mTcO4- persistently appeared in the stomach, thyroid, and salivary glands and did not appear in the lungs. Pharmacokinetic studies showed that 99mTcO4- was rapidly picked up by the stomach wall and secreted promptly into the stomach lumen and that the stomach wall persistently secreted 99mTcO4- into stomach contents for 24 h. By injecting 99mTcO4- through an intratracheal catheter in order to simulate aspiration, the radioactive threshold for imaging intrapulmonary 99mTcO4- was determined to range between less than 0.5 microCi and 2 microCi, depending on the amount of background activity in the blood pool. By measuring the radioactivity in stomach contents (microCi/g), over 24 h after intravenous injection of 2 mCi of 99mTcO4-, we were able to calculate the amount of aspirated stomach contents that our technique should reveal at various time points. We concluded from this preliminary feasibility study that 99mTcO4-, when given intravenously, is suitable to detect pulmonary aspiration of small amounts (less than or equal to 4 ml for 8 h after an intravenous dose of 2 mCi) of gastric contents in human patients. Since our biodistribution studies show that saliva as well as stomach contents are potential sources for any aspirated 99mTcO4-, how to distinguish aspiration of oropharyngeal from stomach contents remains to be determined. It also remains to be determined how long 99mTcO4- remains in the lungs after it has been instilled; clearance that is too rapid significantly decreases the ability of this agent to reveal aspiration.

Animals↗