A way forward in pulmonary aspiration incidence reduction: ultrasound, mathematics, and worldwide data collection

Abstract Aspiration of gastric contents during induction of general anesthesia remains a significant cause of mortality and morbidity in anesthesia. Recent data show that pulmonary aspiration still accounts for many cases with implications on mortality despite technical and technological evolution. Practical, ethical, and methodological issues prevent high-quality research in the setting of aspiration and rapid sequence induction/intubation, and significant controversy is ongoing. Patients' position, drugs choice, dosing and timing, use of cricoid force, and a reliable risk assessment are widely debated with significant questions still unanswered. We focus our discussion on three approaches to promote a better understanding of rapid sequence induction/intubation and airway management decision-making. Firstly, we review how we can use qualitative and quantitative assessment of fasting status and gastric content with the point-of-care ultrasound as an integral part of preoperative evaluation and planning. Secondly, we propose using imaging-based mathematical models to study different patient positions and aspiration mechanisms, including identifying aspiration triggers. Thirdly, we promote the development of a global data collection system aiming to obtain precise epidemiological data. Therefore, we fill the gap between evidence-based medicine and experts' opinion through easily accessible and diffused computer-based databases. A better understanding of aspiration epidemiology obtained through focused global data gathering systems, the widespread use of ultrasound-based prandial status evaluation, and development of advanced mathematical models might potentially guide safer airway management decision making in the 21st century.

Fatores predisponentes do volume residual gástrico após preparo expresso com manitol / Gastric residual volume factors after bowel preparation with mannitol express

ABSTRACT BACKGROUND: Bowel preparation with mannitol is a well-established method in Brazil. However, factors that interfere with the gastric emptying time period are yet to be known. Knowing these factors may favor the examination scheduling logistics and the individualized orientation for each patient. OBJECTIVE: Know the factors that can contribute to the gastric emptying time after intestinal preparation with express mannitol. METHODS: This is a prospective observational study to know factors that may contribute on the gastric emptying timing: predominant type of diet, comorbidities, medication usage, previous surgeries, number of evacuation per week, bearer of bowel obstipation, fecal type, diet type, number of evacuations after the home usage of bisacodyl before the ingestion of mannitol and number of evacuations after the ingestion of mannitol until reaching a proper bowel preparation. Before starting the colonoscopy exam, an upper digestive endoscopy exam was made to aspirate the gastric content. RESULTS: Sample was composed of 103 patients, 55 (53.4%) women, medium age 61 (±12.1) years, medium weight 75.3 (±14.1) kg, medium height 1.7 (±10) m and medium BMI of 26.6 (±3.9) kg/m2. Average gastric residual volume was 120.9 (0-900) mL. Gastric residual volume (GRV) below 100 mL (GRV ≤100 mL) occurred in 45 (43.6%) patients, 24 (53.3%) women, medium age of 61.0 years and medium BMI of 26.7 kg/m2. Gastric residual volume above 100 mL (GRV >100 mL) occurred on 58 (56.3%) patients, 29 (50%) women, medium age of 61.0 years and medium BMI of 26.2 kg/m2. Comparing both groups, average fasting time period after the ingestion of mannitol was significantly higher on the group with GRV ≤100 mL than group with GRV >100 mL, 123.1 (60-246) vs 95.3 (55-195) minutes, respectively. There was also statistical significance concerning the usage of ezetimibe 6 (13.7%) in the group with GRV ≤100 mL and statistical significance in the group with GRV >100 mL concerning the usage of paroxetine 3 (6.7%) and tadalafil 3 (6.7%) and surgical history of prostatectomy 3 (6.7%) and bridle withdrawal 3 (6.7%). CONCLUSION: We may conclude in this study that the usage of ezetimibe and fasting above 2 hours after the ingestion of mannitol decrease significantly the incidence of a GRV >100 mL. The usage of paroxetine, tadalafil and surgical history of prostatectomy or bridle withdrawal may contribute to increase de incidence of a GRV >100 mL.

RESUMO CONTEXTO: O preparo intestinal com manitol é um método bem estabelecido no Brasil. No entanto, os fatores que interferem no tempo de esvaziamento gástrico ainda não são conhecidos. O conhecimento desses fatores pode favorecer a logística de agendamento do exame e a orientação individualizada para cada paciente. OBJETIVO: Estudar os fatores que podem contribuir para o tempo de esvaziamento gástrico após o preparo intestinal com manitol expresso. MÉTODOS: Trata-se de um estudo observacional prospectivo com o objetivo de conhecer os seguintes fatores que podem contribuir no tempo de esvaziamento gástrico: tipo de dieta predominante, comorbidades, uso de medicamentos, cirurgias anteriores, número de evacuações por semana, portador de obstipação intestinal, tipo fecal, tipo de dieta, número de evacuações após o uso domiciliar de bisacodil antes da ingestão de manitol e número de evacuações após a ingestão de manitol até atingir o preparo intestinal adequado. Antes de iniciar o preparo intestinal, os pacientes responderam a um questionário clínico. O endoscópio foi introduzido para aspirar o conteúdo gástrico, antes de iniciar a colonoscopia. RESULTADOS: A amostra foi composta por 103 pacientes, sendo 55 mulheres, com média de idade de 61 anos, peso médio de 75,3 kg, altura média de 1,7 m e IMC médio de 26,6 kg/m2. O volume residual gástrico médio medido foi 120,9 (0-900) mL. Volume residual gástrico inferior a 100 mL (VRG ≤100 mL) foi encontrado em 45 (43,6%) pacientes, sendo 24 (53,3%) mulheres, com média de idade de 61,0 anos e IMC médio de 26,7 kg/m2. Volume residual gástrico acima de 100 mL (VRG >100 mL) ocorreu em 58 (56,3%) pacientes, sendo 29 (50%) mulheres, com idade média de 61,0 anos e IMC médio de 26,2 kg/m2. Comparando os dois grupos, notou-se que o tempo médio de jejum após a ingestão de manitol foi significativamente maior no grupo com VRG ≤100 mL do que no grupo com VRG> 100 mL, 123,1 (60-246) vs 95,3 (55-195) minutos, respectivamente. Também houve significância estatística em relação ao uso de ezetimiba 6 (13,7%), sendo maior no grupo com VRG ≤100 mL. Além disso, houve significância estatística no grupo com VRG >100 mL quanto ao uso de paroxetina 3 (6,7%) e tadalafil 3 (6,7%) e história cirúrgica de prostatectomia 3 (6,7%) e retirada de bridas 3 (6,7%). CONCLUSÃO: Podemos concluir neste estudo que o uso de ezetimiba e o jejum acima de 2 horas após a ingestão de manitol diminuem significativamente a incidência de um VRG> 100 mL. O uso de paroxetina, tadalafil e história cirúrgica de prostatectomia ou retirada de bridas podem contribuir para o aumento da incidência de um VRG >100 mL.

Fatal pulmonary aspiration during balanced sedation with dexmedetomidine and midazolam: A case report

Recently, balanced sedation has commonly been used during procedural sedation. Dexmedetomidine is known for its relative safety to cause “conscious sedation” with little respiratory depression but has some limitations such as frequent awakening and hemodynamic instability during surgery. To facilitate sedation, a small dose of midazolam can be co-administered rather than escalating the dose of dexmedetomidine, especially in elderly patient. Despite the respiratory safety profile of dexmedetomidine, the overall safety of co-administration has not been clarified. We describe the first case of fatal pulmonary aspiration that developed in an elderly patient during balanced sedation with spinal anesthesia for elective femur fracture surgery.

¿El reflujo gastroesofágico y la aspiración de contenido gástrico están implicados en la etiopatogenia y la progresión de la fibrosis pulmonar idiopática? / Does gastroesophageal reflux and gastric content aspiration have some role in the pathogenesis and progression of Idiopathic Pulmonary Fibrosis?

Resumen El reflujo gastroesofágico (RGE) y la aspiración oculta de contenido digestivo están probablemente implicados en la etiopatogenia y progresión de la fibrosis pulmonar idiopática (FPI). Los mecanismos patogénicos involucrados son la disminución de la distensibilidad pulmonar y el consiguiente aumento de la presión negativa intratorácica durante la inspiración, así como la disminución de los mecanismos de control de la motilidad esofágica o del tono del esfínter esofágico inferior. La prevalencia de RGE y anomalías de la motilidad esofágica están aumentadas en los pacientes con FPI comparado con la población general. Entre los pacientes con FPI, el 67-76% demostraron exposición anormal al contenido ácido en el esófago. Sin embargo, no hubo relación entre la gravedad del RGE y la gravedad de la FPI. Los estudios que han examinado el tratamiento antirreflujo en esta población han sido escasos. Incluso, algunos datos sugieren que el tratamiento antiácido puede ser perjudicial en algunos pacientes con esta condición. Después de analizar toda la evidencia relevante encontrada hasta la fecha, concluimos que no se puede establecer una relación causal entre el RGE, la aspiración del contenido gástrico y la patogénesis de la FPI. Además, existe escasa evidencia clínica que haya examinado el tratamiento antirreflujo en pacientes con fibrosis pulmonar idiopática.

ABSTRACT Gastroesophageal reflux (GERD) and hidden aspiration of gastric contents are probably involved in the pathogenesis and progression of idiopathic pulmonary fibrosis (IPF). The pathological mechanisms involved are decreased pulmonary distensibility and consequent increase of intrathoracic negative pressure during inspiration, as well as decreased control mechanisms of esophageal motility or lower esophageal sphincter. The prevalence of GERD and oesophageal dysmotility was higher in patients with IPF as compared with general population. Among patients with IPF, 67-76% demonstrated abnormal oesophageal acid exposure. However, no relationship was demonstrated between severity of GERD and severity of IPF. Data are scant on outcomes of antireflux treatment in patients with IPF. Actually, some data suggests that antacid treatment may be deleterious in some IPF patients. After analyzing all the relevant evidence found to date, a causal relationship between GERD, gastric content aspiration and IPF pathogenesis cannot be established. There is scant evidence examining antireflux treatment in idiopathic pulmonary fibrosis patients.

Effectiveness of the endotracheal tube cuff on the trachea: physical and mechanical aspects / Eficácia do balonete do tubo endotraqueal sobre a traqueia: aspectos físicos e mecânicos

Introduction: The inflation pressure of the endotracheal tube cuff can cause ischemia of the tracheal mucosa at high pressures; thus, it can cause important tracheal morbidity and tracheal microaspiration of the oropharyngeal secretion, or it can even cause pneumonia associated with mechanical ventilation if the pressure of the cuff is insufficient. Objective: In order to investigate the effectiveness of the RUSCH® 7.5 mm endotracheal tube cuff, this study was designed to investigate the physical and mechanical aspects of the cuff in contact with the trachea. Methods: For this end, we developed an in vitro experimental model to assess the flow of dye (methylene blue) by the inflated cuff on the wall of the artificial material. We also designed an in vivo study with 12 Large White pigs under endotracheal intubation. We instilled the same dye in the oral cavity of the animals, and we analyzed the presence or not of leakage in the trachea after the region of the cuff after their deaths (animal sacrifice). All cuffs were inflated at the pressure of 30 cmH2O. Results: We observed the passage of fluids through the cuff in all in vitro and in vivo experimental models. Conclusion: We conclude that, as well as several other cuff models in the literature, the RUSCH® 7.5 mm tube cuffs are also not able to completely seal the trachea and thus prevent aspiration of oropharyngeal secretions. Other prevention measures should be taken. .

Introdução: A pressão de insuflação do balonete (cuff) do tubo endotraqueal tanto pode causar isquemia de mucosa traqueal em pressões elevadas, e assim ocasionar morbidade traqueal importante, quanto pode causar microaspiração traqueal de secreção de orofaringe ou, ainda, ocasionar pneumonia associada à ventilação mecânica, caso a pressão do balonete seja insuficiente. Objetivo: A fim de investigar a eficácia do balonete do tubo endotraqueal RUSCH® 7,5mm, este estudo foi desenhado para investigar aspectos físicos e mecânicos do balonete em contato com a traqueia. Métodos: Para isto, foi desenvolvido modelo experimental in vitro para avaliar o escoamento de corante (azul de metileno) pelo balonete insuflado na parede de material artificial. Também foi desenhado estudo in vivo com 12 porcos da raça Large-White sob intubação endotraqueal. Foi instilado o mesmo corante na cavidade oral do animal e após óbito (sacrifício do animal) foi analisada a presença ou não de vazamento deste na traqueia pós-região do balonete. Todos os balonetes foram insuflados na pressão de 30 cmH2O. Resultados: Houve passagem de fluidos pelo balonete em todos os modelos experimentais in vitro e in vivo. Conclusão: Podemos concluir que, assim como diversos outros modelos de balonetes na literatura, balonetes do tubo RUSCH® 7,5mm também não são capazes de vedar completamente a traqueia e com isso prevenir aspiração de secreções orofaríngeas. Outras medidas para a prevenção devem ser tomadas. .

Effectiveness of milrinone for cardiogenic shock due to massive pulmonary aspiration: a case report / 대한마취과학회지

Pulmonary aspiration of gastric contents is one of the most frightening complications during anesthesia. Although pulmonary aspiration of gastric contents in general surgical patients is not common and resulting long-term morbidity and mortality are rare, severe hypoxemia and other sequelae of pulmonary aspiration continue to be reported. We report a case of massive aspiration of gastric contents during induction of general anesthesia, resulting in cardiac arrest due to severe pulmonary hypertension and myocardial infarction. Sustained cardiac arrest and shock that did not respond the conventional resuscitation was successfully treated using milrinone. The patient was discharged without complications in 20 days.

Usefulness of the Simplified Cough Test in Evaluating Cough Reflex Sensitivity as a Screening Test for Silent Aspiration

OBJECTIVE: To assess cough reflex sensitivity using the simplified cough test (SCT) and to evaluate the usefulness of SCT to screen for silent aspiration. METHODS: The healthy control group was divided into two subgroups: the young (n=29, 33.44+/-9.99 years) and the elderly (n=30, 63.66+/-4.37 years). The dysphagic elderly group (n=101, 72.95+/-9.19 years) consisted of patients with dysphagia, who suffered from a disease involving central nervous system (ischemic stroke 47, intracerebral hemorrhage 27, traumatic brain injury 11, encephalitis 5, hypoxic brain damage 3, and Parkinson disease 8). The SCT was performed using the mist of a 1% citric acid from a portable nebulizer. The time from the start of the inhalation to the first cough was measured as the cough latency. All the dysphagic patients underwent the videofluoroscopic swallowing study. RESULTS: The cough latency was more significantly prolonged in the healthy elderly group than in the healthy young group (p<0.001), and in the dysphagic elderly group than in the healthy elderly group (p<0.001). The sensitivity and specificity of SCT were 73.8% and 72.5% for detecting aspiration in the dysphagic patients, and 87.1% and 66.7% for detecting silent aspiration in the aspirated patients. CONCLUSION: Cough latency measured with the SCT reflects the impairment of cough reflex in healthy elderly and dysphasic subjects. The results of this study show that the SCT test can be a valuable method of screening aspiration with or without cough in dysphasic patients.