Aspiration pneumonia

Utilization of Oil Red O staining for assessing aspiration risk in lung transplant patients: A multidisciplinary prospective study with clinical practice insights

BACKGROUND

Gastroesophageal reflux disease with microaspiration has been associated with graft dysfunction in lung transplant patients. Identifying patients with aspiration is clinically important because it enables implementation of appropriate interventions like antireflux therapy. Oil Red O (ORO) staining with determination of the lipid-laden macrophage index (LLMI) has been proposed as a noninvasive surrogate marker in the detection of aspiration. The aim of this study was to prospectively evaluate clinical utilization of ORO staining in the assessment of aspiration risk.

METHODS

All transbronchial surgical pathology biopsies obtained in lung transplant patients undergoing routine surveillance from August 2020 through November 2021 were included in this study. Clinical team members prospectively ascertained the aspiration risk category (ARC) of each patient both before and after biopsy findings and recorded reasons for change in ARC.

RESULTS

A total of 132 transbronchial biopsies with concurrent LLMI were included in the study. LLMI was low in 51 cases (38.6%), including 21 of the 54 cases (38.9%) where aspiration was suggested based on the transbronchial biopsy findings. In total, 19 cases (14.4%) underwent a change in ARC post-biopsy including 10 that were upgraded and nine cases that were downgraded. Transbronchial biopsy findings were noted as the reason for change in ARC in the majority (15/19; 79%) of cases; only a minority (2/19; 10.5%) were due to the LLMI. Notably, 16 cases (12.1%) had a low LLMI with high-risk post-biopsy ARC and nine cases (6.8%) had a high LLMI with low-risk post-biopsy ARC.

CONCLUSIONS

This study observed that clinical evaluation for aspiration relied more heavily on transbronchial biopsy findings. Although LLMI may retain clinical utility in some scenarios, reevaluation of the clinical value of ORO testing would be prudent.

Critical aspiration pneumonia during induction of anesthesia in elective abdominal surgery: a case report

Background

We experienced the critical aspiration pneumonia during induction of anesthesia in elective abdominal surgery which standard fasting period was complied with.

Case presentation

A 64-year-old male was scheduled for gastrojejunostomy because of gastrointestinal obstruction. He fasted from the night before surgery. General anesthesia was induced, and cricoid pressure was applied during intubation. However, he vomited huge amount of gastric contents. The scheduled surgery was performed without surgical complications, and postoperatively respiratory management, including mechanical ventilation with prone positioning, was performed in high care unit. He was extubated on postoperative day 2. He was discharged from the hospital on POD 25.

Conclusion

The standard fasting period can prevent aspiration pneumonia in most cases. However, even in elective cases without abdominal symptoms, we consider that massive-volume gastric residual contents, especially in susceptible cases. We suggest that point-of-care gastric ultrasonography be performed in suspicious cases before induction of anesthesia.

Correlation between cytology Oil Red O staining and lung biopsy specimens: utility of the lipid-laden macrophage index

INTRODUCTION

Oil Red O staining is used for enumeration of the lipid-laden macrophage index (LLMI) as a surrogate for aspiration. As part of quality improvement efforts aimed at optimizing resource utilization, the utility of this stain in current cytopathology practice was re-evaluated. The objective of this study was to explore the clinical utility of Oil Red O staining in bronchoalveolar lavage (BAL) samples by correlating the LLMI with findings in concurrent histologic tissue samples.

MATERIALS AND METHODS

Lung transbronchial biopsy specimens that suggested aspiration that were submitted with concurrent BAL cytology samples were retrieved. Lung tissue biopsies were reviewed for the presence of foamy alveolar macrophages (graded as 0, 1+, and 2+), foreign material, and giant cells. The concurrent BAL was reviewed with consensus determination of the LLMI.

RESULTS

A total of 53 cases were identified. On histology, 13 cases (24.5%) were found to have no foamy alveolar macrophages, 23 cases (43.4%) were found to have 1+ foamy alveolar macrophages, and 17 cases (32.1%) were found to have 2+ foamy alveolar macrophages. Six cases (11.3%) were found to have foreign material, and 10 cases (18.9%) were found to have multinucleated giant cells. The average LLMI score was 16, with 44 (83.0%) in the low range (LLMI <40) and 9 (17.0%) in the intermediate range (LLMI of 40-90).

CONCLUSIONS

None of the cases in our study had an LLMI that exceeded the cutoff value for which aspiration would be suspected. We found no correlation of the LLMI with lung biopsies that suggested aspiration.

Preventing Respiratory Complications of Tube Feedings: Evidence-Based Practice

The most dreaded complication of tube feedings is tracheobronchial aspiration of gastric contents. Strong evidence indicates that most critically ill tube-fed patients receiving mechanical ventilation aspirate gastric contents at least once during their early days of tube feeding. Those who aspirate frequently are about 4 times more likely to have pneumonia develop than are those who aspirate infrequently. Although a patient’s illness might not be modifiable, some risk factors for aspiration can be controlled; among these are malpositioned feeding tubes, improper feeding site, large gastric volume, and supine position. A review of current research-based information to support modification of these risk factors is provided.

Enteral nutrition

This article briefly reviews the literature supporting the use of enteral nutrition, which appears to be the preferred method of nutritional support in critically ill patients. Patients who benefit the most from this type of support, as well as the administration and route preferences in enteral nutrition, are discussed. In addition, the different types of enteral formulas and the more frequently associated complications that occur with tube feedings are reviewed.

Certification of staff nurses to insert enteral feeding tubes using a research-based procedure

Nutrition Support Nurse Clinicians at a Central Texas tertiary care facility have developed a research-based nasoenteric feeding tube insertion procedure that minimizes the potential for inadvertent passage of a feeding tube containing a stylet into the respiratory tract and maximizes placement of the feeding tube in the desired gastric or duodenal location. The first 79 staff nurses to be certified to use the technique had a 90% duodenal placement success rate under supervision. No bedside feeding tube insertion complications have been noted since the initiation of the certification program 6 years ago. This article describes the feeding tube insertion technique used in the certification process and the research on which it is based.

Long-term enteral access in aspiration-prone patients

Aspiration pneumonia is a serious complication of enteral feeding. Many critically ill patients are particularly at risk for aspiration. Few studies have rigorously compared various access devices. Risk factors for aspiration and studies examining aspiration associated with enteral feeding devices are reviewed. We recommend a surgical jejunostomy for all patients at high risk for aspiration who require more than 3 weeks of enteral nutrition support.

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.

The prevention and treatment of aspiration of vomitus during pharmacosedation and general anesthesia

The aspiration of gastric contents can occur in patients with a depressed level of consciousness. Pulmonary aspiration is a serious potential complication of pharmacosedation and general anesthesia. Sequelae associated with aspiration include pulmonary obstruction, chemical pneumonitis, secondary infection, and possibly death. Morbidity following aspiration is enhanced with an increased volume of aspirate, a more acidic pH, a high particle content, and bacterial contamination. Treatment of aspiration is dependent on the nature of the aspirate. Identifying aspiration-susceptible patients, employing preventive measures, and using careful anesthetic technique can effectively reduce the risk of aspiration.

Enteral nutrition in patients with tumours of the head and neck

An evaluation is presented of the nutritional status of 30 patients out of the 45 submitted to head and neck surgery, involving the buccal cavity, in the Maxillofacial Surgery Service of the General Hospital "Gregorio Marañón" of Madrid, between October 1985 and December 1986, before and after being submitted to excision of a tumour in the head or neck, by administration, in the postoperative period, of a liquid comprehensive diet via a nasogastric catheter. Neither in the postoperative period nor after stopping the enteral nutrition was the existence of malnutrition detected, in any of the parameters studied. One patient inhaled gastric juice with a fatal outcome, while the rest of the patients had no severe complications. Therefore, we think that the administration of enteral nutrition in this kind of patient is very useful and is indeed necessary to avoid energy-protein malnutrition during the postoperative period. At the same time it avoids possible infection by food remaining in the oral cavity.

A retrospective survey of treatment and mortality in aspiration pneumonia

A retrospective survey was conducted of all patients with severe aspiration pneumonitis requiring artificial ventilation in our Intensive Care Unit from 1982-1986 inclusive. Of 38 patients, 8 (21%) died. Five of these deaths were due to severe primary intracranial pathology, and occurred after complete or almost complete resolution of the pneumonitis. One death (2.5%) due to myocardial infarction was possibly related to aspiration, and 2 deaths (5%) were definitely related to aspiration. The 7.5% mortality related to aspiration is considerably lower than in previous clinical studies of severe aspiration pneumonia. There was only one death due to aspiration in patients under the age of 70. The mean arterial to alveolar oxygen tension ratio was 0.221, and the mean predicted mortality by apache II was 43%. Patients were managed with rapid intravascular volume restoration using crystalloid fluids, early ventilation, no steroids, and no immediate antibiotics. We conclude that with such management it is possible to achieve a low hospital mortality in severe aspiration pneumonia, particularly in young patients.

Recurrent aspiration in children: lipid-laden alveolar macrophage quantitation

We prospectively evaluated bronchial washings from 45 patients aged 1 month to 25 years (mean 3.3 years) for the presence of lipid-laden macrophages. By grading the amount of intracellular oil-red-O-positive material, we determined a semiquantitative lipid-laden macrophage index for each patient. All patients observed to be definite aspirators (n = 22) had indexes greater than or equal to 86 (mean +/- SD, 139 +/- 46). All patients with no clinical suspicion of aspiration (n = 23) had indexes less than or equal to 72 (mean +/- SD, 21 +/- 20). Our results suggest that simply sighting lipid-laden macrophages in a nonspecific finding, but quantitation of these cells may be a very good test for recurrent aspiration of food substances in children. This test appears to be more sensitive than radiographic studies.

Pulmonary consequences of severe tricyclic antidepressant ingestion

We prospectively studied 56 consecutive patients with severe tricyclic antidepressant ingestion to determine the incidence of associated pulmonary complications. Among the patients meeting the entrance criteria, the mean antidepressant level was 1136 ng/ml. Other characteristics were a QRS duration of greater than or equal to 0.1 seconds in 35 (63%) and seizures in 19 (34%). Seventeen patients (30%) developed 18 abnormal chest X-ray findings which included pulmonary edema in 8 cases and aspiration pneumonia in 10. Using logistic regression, we evaluated the influence of tricyclic antidepressant level, blood pressure, QRS interval, seizures, drug co-ingestion and the use of gastric lavage vs. ipecac-induced emesis on pulmonary complications. For patients with pulmonary edema, the only significantly associated factor was hypotension on emergency department presentation. For aspiration pneumonia, no significant associations were found. Co-ingestion of another drug had no apparent influence on the development of pulmonary abnormalities. Our findings suggest that pulmonary edema and aspiration pneumonia are frequent complications of severe ingestions of tricyclic antidepressants. Pulmonary edema appears to result from hypotension or its treatment. The etiology of aspiration pneumonia is unclear. A chest X-ray should be obtained in all victims of tricyclic antidepressant overdose.

Complications of enteral nutrition

Complications may arise during enteral feeding that are usually related to the diameter and rigidity of the tube or the delivery, composition, and sterility of the feed uses. By using a soft, fine bore tube to deliver a sterile feed of known composition, by continuous infusion rather than as a bolus, most of these complications can be avoided.