Gastric emptying after oral contrast for abdominal tomography: report of six cases

Martins, Fernando Antonio Nogueira da Cruz; Amaral, José Luiz Gomes do

doi:10.1590/S0034-70942004000300009

Abstracts

BACKGROUND AND OBJECTIVES: Pulmonary injury due to gastric contents aspiration is a complication related to airway protective reflexes loss. Tomography imaging with digestive tract contrast requires special care for children below five years of age requiring general anesthesia or sedation to assure immobility during the procedure. General anesthesia induction or sedation after contrast ingestion may pose substantial risk for gastric contents bronchoaspiration, so contrast administration by gastric tube is often used after tracheal intubation, since time elapsed for emptying gastric contrast is unknown. This practice means increased anesthesia duration and leads to issues about the possibility of gastric emptying in less than one hour. Six patients submitted to abdominal tomography were evaluated concerning gastric emptying by tomographic slices in stomach topography to establish whether residual liquid contents remain in that organ after contrast administration. CASES REPORT: Participated in this study 6 children undergoing abdominal tomography. Two conscious children presented expressive gastric liquid residual 50 and 45 minutes, respectively, after oral contrast ingestion. Four anesthetized children have also presented gastric liquid residual 40-50 minutes after contrast administration through gastric tube. In two of them remarkable gastric liquid content remained even after stomach aspiration. CONCLUSIONS: In all studied cases, forty to fifty minutes were not enough for gastric emptying after contrast administration and even stomach aspiration trough gastric tube has resulted in significant residual liquid.

ANESTHESIA; COMPLICATIONS; FASTING; THERAPY AND DIAGNOSTIC PROCEDURES

JUSTIFICATIVA E OBJETIVOS: A lesão pulmonar secundária à aspiração do conteúdo gástrico é complicação associada à perda dos reflexos protetores das vias aéreas. Neste contexto, a realização de exames tomográficos que incluem a contrastação do trato digestivo exige particular atenção em crianças abaixo de cinco anos, que necessitam anestesia geral ou sedação para assegurar imobilidade durante o procedimento. A indução da anestesia ou sedação, após ingestão da solução de contraste pode trazer risco substancial para a broncoaspiração do conteúdo gástrico. Isto faz com que se opte por administrar o contraste por sonda gástrica após a intubação traqueal, uma vez que não se conhece o tempo de esvaziamento gástrico após utilização de solução contrastante. Esta conduta representa aumento do tempo de anestesia, o que resulta em constante questionamento sobre a possibilidade de esvaziamento do conteúdo gástrico em tempo inferior a uma hora. Seis casos de pacientes submetidos à tomografia de abdômen foram avaliados quanto ao esvaziamento gástrico por meio da realização de cortes tomográficos na topografia do estômago, com o objetivo de determinar a presença ou ausência de conteúdo residual líquido nesse órgão, após a administração da solução de contraste. RELATO DOS CASOS: Foram avaliadas seis crianças submetidas à tomografia contrastada do abdômen. Duas, não anestesiadas, apresentaram expressivo resíduo líquido gástrico decorridos 50 e 45 minutos, respectivamente, da ingestão de contraste. Quatro, submetidas à anestesia geral, também apresentaram resíduo líquido gástrico decorridos 40 a 50 minutos da administração de contraste via sonda oro/nasogástrica. Em duas destas persistiu apreciável resíduo líquido no estômago, mesmo após a aspiração do conteúdo pela sonda. CONCLUSÕES: Nos casos observados, o período de 40 a 50 minutos foi insuficiente para o esvaziamento do estômago, após a administração de solução contrastante e mesmo a sucção do conteúdo por sonda nasogástrica resultou em permanência de significante volume residual líquido.

ANESTESIA; COMPLICAÇÕES; JEJUM; PROCEDIMENTOS DE DIAGNOSE E TERAPIA

JUSTIFICATIVA Y OBJETIVOS: La lesión pulmonar secundaria a la aspiración del contenido gástrico es complicación asociada a la pérdida de los reflejos protectores de las vías aéreas. En este contexto, la realización de exámenes tomográficos que incluyan la contrastación del tracto digestivo, exige particular atención en niños menores de cinco años, que necesitan anestesia general o sedación, para asegurar inmovilidad durante el procedimiento. La inducción de la anestesia o sedación después de ingestión de la solución de contraste puede traer riesgo substancial para la broncoaspiración del contenido gástrico. Esto hace con que se opte por administrar el contraste por sonda gástrica después de la intubación traqueal, una vez que no se conoce el tiempo de vaciamiento gástrico después de utilización de solución contrastante. Esta conducta representa aumento del tiempo de anestesia, lo que resulta en constante cuestionamiento sobre la posibilidad de vaciamiento del contenido gástrico en tiempo inferior a una hora. Seis casos de pacientes sometidos a tomografía de abdomen fueron evaluados cuanto al vaciamiento gástrico por medio de la realización de cortes tomográficos en la topografía del estomago, con el objetivo de determinar la presencia o ausencia del contenido residual líquido en ese órgano, después de la administración de la solución de contraste. RELATO DE LOS CASOS: Fueron evaluados seis niños sometidos a tomografía contrastada del abdomen. Dos, no anestesiados, presentaron expresivo residuo líquido gástrico pasados 50 y 45 minutos, respectivamente, de la ingestión de contraste. Cuatro, sometidos a anestesia general, también presentaron residuo líquido gástrico pasados 40 a 50 minutos de la administración de contraste vía sonda oro/nasogástrica. En dos de ellos persistió apreciable residuo líquido en el estomago, igualmente después de la aspiración del contenido por la sonda. CONCLUSIONES: En los casos observados, el tiempo de 40 a 50 minutos fue insuficiente para el vaciamiento del estomago después de la administración de solución contratante e igualmente la succión del contenido por sonda nasogástrica resultó en permanencia de significante volumen residual líquido.

CLINICAL REPORT

Gastric emptying after oral contrast for abdominal tomography. Report of six cases^* * Received from Setor de Tomografia Computadorizada do Departamento de Diagnóstico por Imagem do Hospital São Paulo da Escola Paulista de Medicina da Universidade Federal de São Paulo (EPM UNIFESP), SP

Vaciamiento gástrico después de la administración oral de contraste en tomografía computadorizada del abdomen: Descripción de seis casos

Fernando Antonio Nogueira da Cruz Martins, M.D.^I; José Luiz Gomes do Amaral, TSA, M.D.^II

^IAnestesiologista Responsável pelo Setor de Tomografia Computadorizada da EPM UNIFESP, Hospital São Paulo

^IIProfessor Titular da Disciplina de Anestesiologia, Dor e Terapia Intensiva da EPM UNIFESP, Hospital São Paulo

^{Correspondence} Correspondence to Dr. Fernando Antonio Nogueira da Cruz Martins Rua Dr. Diogo de Faria, 513/24 Vila Clementino 04037-001 São Paulo, SP

SUMMARY

BACKGROUND AND OBJECTIVES: Pulmonary injury due to gastric contents aspiration is a complication related to airway protective reflexes loss. Tomography imaging with digestive tract contrast requires special care for children below five years of age requiring general anesthesia or sedation to assure immobility during the procedure. General anesthesia induction or sedation after contrast ingestion may pose substantial risk for gastric contents bronchoaspiration, so contrast administration by gastric tube is often used after tracheal intubation, since time elapsed for emptying gastric contrast is unknown. This practice means increased anesthesia duration and leads to issues about the possibility of gastric emptying in less than one hour. Six patients submitted to abdominal tomography were evaluated concerning gastric emptying by tomographic slices in stomach topography to establish whether residual liquid contents remain in that organ after contrast administration.

CASES REPORT: Participated in this study 6 children undergoing abdominal tomography. Two conscious children presented expressive gastric liquid residual 50 and 45 minutes, respectively, after oral contrast ingestion. Four anesthetized children have also presented gastric liquid residual 40-50 minutes after contrast administration through gastric tube. In two of them remarkable gastric liquid content remained even after stomach aspiration.

CONCLUSIONS: In all studied cases, forty to fifty minutes were not enough for gastric emptying after contrast administration and even stomach aspiration trough gastric tube has resulted in significant residual liquid.

Key Words: ANESTHESIA, Pediatric; COMPLICATIONS: bronchoaspiration; FASTING; THERAPY AND DIAGNOSTIC PROCEDURES: computer tomography

RESUMEN

JUSTIFICATIVA Y OBJETIVOS: La lesión pulmonar secundaria a la aspiración del contenido gástrico es complicación asociada a la pérdida de los reflejos protectores de las vías aéreas. En este contexto, la realización de exámenes tomográficos que incluyan la contrastación del tracto digestivo, exige particular atención en niños menores de cinco años, que necesitan anestesia general o sedación, para asegurar inmovilidad durante el procedimiento. La inducción de la anestesia o sedación después de ingestión de la solución de contraste puede traer riesgo substancial para la broncoaspiración del contenido gástrico. Esto hace con que se opte por administrar el contraste por sonda gástrica después de la intubación traqueal, una vez que no se conoce el tiempo de vaciamiento gástrico después de utilización de solución contrastante. Esta conducta representa aumento del tiempo de anestesia, lo que resulta en constante cuestionamiento sobre la posibilidad de vaciamiento del contenido gástrico en tiempo inferior a una hora. Seis casos de pacientes sometidos a tomografía de abdomen fueron evaluados cuanto al vaciamiento gástrico por medio de la realización de cortes tomográficos en la topografía del estomago, con el objetivo de determinar la presencia o ausencia del contenido residual líquido en ese órgano, después de la administración de la solución de contraste.

RELATO DE LOS CASOS: Fueron evaluados seis niños sometidos a tomografía contrastada del abdomen. Dos, no anestesiados, presentaron expresivo residuo líquido gástrico pasados 50 y 45 minutos, respectivamente, de la ingestión de contraste. Cuatro, sometidos a anestesia general, también presentaron residuo líquido gástrico pasados 40 a 50 minutos de la administración de contraste vía sonda oro/nasogástrica. En dos de ellos persistió apreciable residuo líquido en el estomago, igualmente después de la aspiración del contenido por la sonda.

CONCLUSIONES: En los casos observados, el tiempo de 40 a 50 minutos fue insuficiente para el vaciamiento del estomago después de la administración de solución contratante e igualmente la succión del contenido por sonda nasogástrica resultó en permanencia de significante volumen residual líquido.

INTRODUCTION

Pulmonary injury secondary to gastric contents aspiration is a relevant complication associated to airways protective reflexes loss determined by general anesthesia ¹. Among factors contributing to this event there are gastric content volume and characteristics, such as pH, presence of particles, colonization, etc. In adults, gastric contents equal to or above 25 mL ² in pH equal to or below 2.5 ³ is a critical situation, although predictive values for aspiration are questionable and do not take into consideration other factors contributing for aspiration pathogenesis and prevention ⁴.

Pregnancy, stress ⁵, emergency procedures ⁶, age extremes ⁷, obesity ⁸, trauma, pain, drugs (especially opioids), among others, are followed by gastric emptying delay and increased stomach acid secretion, being risk factors for aspiration.

The incidence of gastric contents aspiration is estimated in 0.8 to 4.7 cases in 10 thousand anesthesias, being 4.3 times more frequent in emergency procedures ^5,6,8,9.

It is a complication expected during to anesthetic induction and tracheal intubation associated to airway instrumentation and protective reflexes loss. However, approximately 50% of postoperative aspirations are recorded ⁹.

Clinical expression (cough, wheezing, hypoxemia or radiological consolidation) is not present in the next two hours after the event in 64% of cases ¹⁰.

Such considerations lead to preoperative fasting adapted to different clinical situations and age brackets. The American Association of Anesthesiologists (ASA) ¹¹ recommends clear fluids fasting of at least 2 hours. Water, coffee (plain), tea, soft drinks and fruit juice without pulp are considered clear fluids, among others. Light meals with toasts, tea or coffee (plain) are allowed up to 6 hours before the procedure. For breast milk it is suggested at least 4 hours fasting and for pediatric formulas at least 6 hours. Non-human milk is not included among clear fluids because it results in solid residues. At least 6 hours fasting is recommended between non-human milk ingestion and the procedure. Solid foods, especially meat and fatty matters require prolonged fasting. These foods are forbidden on surgery day. Patients to be operated on in the morning (after 6:00 a.m.) are oriented to fast as from 10:00 p.m. of previous day that is a fasting period of at least 8 hours. Minor amounts of water to ingest preanesthetic medication or other oral drugs have no inconvenient and are allowed ¹¹.

Tomographic images with contrast ingestion require special attention. From the available alternatives, there is the possibility of administering contrast orally or through gastric tube, as a function of patient's cooperation for ingestion and immobility during the procedure.

In younger children (in general below 5 years of age), general anesthesia or sedation is needed to assure immobility during the procedure. Anesthesia or sedation induction after contrast ingestion may pose substantial risk for gastric contents aspiration and this leads to the option of administering contrast by gastric tube after tracheal intubation in previously anesthetized patients since gastric contents emptying time after contrast ingestion is not known. This method represents considerable increase in anesthesia duration and has led to continuous questioning about the possibility of gastric content emptying in less than one hour. This report aimed at describing 6 cases of children submitted to abdominal tomography who were evaluated in terms of gastric emptying through tomographic slices of stomach topography. We have tried to determine the presence or absence of liquid contents in this organ 40 to 50 minutes after contrast ingestion.

CASE REPORTS

Participated in this study 6 children submitted to abdominal tomography after contrast ingestion.

Contrast was meglumine ioxithalamate, made up of triiodate acid (ioxithalamic acid), meglumine, trihydrated monosodic phosphate and sodium calcium edetate. Its iodine content is 300 mg.mL^-1 with 66% concentration and osmolality of 1650 mOsm.kg^-1 of water (information obtained from substance's package insert).

According to the protocol of the Image Diagnostic Department, Hospital São Paulo, EPM/UNIFESP, oral contrast volume for abdominal tomography is 30 mL.kg^-1 of patient's weight, with 3% contrast in 5% glucose solution, juice or water, in equal fractions at 10-minute intervals and time elapsed between beginning of ingestion and tomography is 2 hours. Images start immediately after the last fraction ingestion.

In anesthetized patients, contrast is administered after general anesthesia induction and tracheal intubation, via nasograstric tube positioned by the anesthesiologist. Images start 20 minutes after contrast infusion.

Case 1

Female patient, 6 years old, with clinical history of abdominal pain for 4 days, vomiting and fever and suspicion of psoitis. Patient was not anesthetized because she was cooperative in ingesting contrast and staying immobile during the procedure. Tomographic slices of stomach topography have shown the presence of liquid gastric contents 50 minutes after ingesting the last contrast fraction (Figure 1).