Ultrasonographic evaluation of gastric content and volume: a systematic review

SUMMARY OBJECTIVE: Bronchoaspiration of gastric content is associated with high morbidity and mortality, but evaluating this complication is a difficult task. However, gastric ultrasonography can safely assess gastric content and prevent bronchoaspiration. Therefore, a systematic review was performed in order to verify the efficacy of ultrasonography in the qualitative and quantitative analyses of gastric content. METHODS: A literature review of articles published between 2009 and 2019 in the PubMed and LILACS databases was conducted using combinations of the keywords "gastric ultrasound," "gastric emptying," and "gastric content." RESULTS: Of the 20 articles found, 19 chose the antral region as the best site for qualitative analysis of the gastric content. Regarding quantitative measurement, the most commonly used method to calculate the gastric volume in eight articles was the formula "Gastric Volume = 27 + (14.6 × ATAG) − (1.28 × Age)," in which the area of the transverse section of the gastric antrum (ATAG) could also be calculated by the largest antral diameters or by free tracing. CONCLUSION: An efficient evaluation of the gastric content can be performed by ultrasonography of the antral region, contributing to greater safety in the clinical management of patients with increased risk for bronchoaspiration during airway management.

RESUMO OBJETIVO: A broncoaspiração do conteúdo gástrico associa-se à alta morbimortalidade, porem a avaliação desta complicação é tarefa dificil. Por outro lado, a ultrassonografia gástrica avalia o conteúdo gástrico com segurança, podendo evitar a broncoaspiração. Portanto, foi realizada revisão sistemática com objetivo de verificar a aplicabilidade da ultrassonografia na análise qualitativa e quantitativa do conteúdo gástrico. MÉTODOS: Revisão de literatura de artigos publicados entre 2009 e 2019 nas bases de dados PubMed e LILACS usando combinações das palavras chave: "Gastric ultrasound", "gastric emptying" e "gastric content". RESULTADOS: Foram encontrados 20 artigos. A região antral foi escolhida em 19 artigos como melhor local do ponto de vista qualitativo para analisar o conteúdo gástrico. A respeito da mensuração quantitativa, o método mais utilizado para cálculo do volume gástrico, escolhido em 8 artigos, foi através da fórmula Volume gástrico = 27 + (14,6 x ATAG) - (1,28 x Idade), em que a Área da Secção Transversa do Antro Gástrico (ATAG) pode ser igualmente calculada pelos maiores diâmetros antrais ou pelo seu traçado livre. CONCLUSÃO: A ultrassonografia da região antral permite boa avaliação do conteúdo gástrico, trazendo maior segurança ao manejo clínico de pacientess com risco aumentado para broncoaspiração no manejo da via aerea.

Ultrasound dynamics of gastric content volumes after the ingestion of coconut water or a meat sandwich. A randomized controlled crossover study in healthy volunteers / Dinâmica ultrassonográfica dos volumes do conteúdo gástrico após a ingestão de água de coco ou sanduíche de carne. Um estudo cruzado controlado e randômico com voluntários saudáveis

Abstract Background: Adequate preoperative fasting is critical in preventing pulmonary aspiration of gastric content. We proposed to study the sonographic gastric content dynamics after the ingestion of liquid or solid food in healthy volunteers and confront it with current guidelines for preoperative fasting times. Methods: We performed a prospective, crossover, evaluator-blinded study involving 17 healthy volunteers of both sexes. Each participant fasted for 10 h and was subjected to a baseline gastric ultrasound, intake of 400 mL of coconut water or a 145 g, 355 kcal meat sandwich, and sonographic gastric evaluations after 10 min and every hour until the stomach was completely empty. Results: At baseline, all subjects had an empty stomach. At 10 min, gastric content [mean + standard deviation (SD)] was 240.4 + 69.3 and 248.2 + 119.2 mL for liquid and solid foods, respectively (p > 0.05). Mean + SD gastric emptying times were 2.5 + 0.7 and 4.5 + 0.9 h for liquid and solid foods, respectively (p < 0.001). For the drink, the stomach was completely empty in 59% and 100% of the subjects after two and four hours, and for the sandwich, 65% and 100% of the subjects after four and seven hours, respectively. Conclusions: Sonographic gastric dynamics for coconut water and a meat sandwich resulted in complete gastric emptying times higher and lower, respectively, than those suggested by current guidelines for preoperative fasting.

Resumo Justificativa: O jejum pré-operatório adequado é fundamental para prevenir a aspiração pulmonar do conteúdo gástrico. Nossa proposta foi avaliar a dinâmica ultrassonográfica do conteúdo gástrico após a ingestão de alimentos líquidos ou sólidos em voluntários sadios e confrontá-la com as diretrizes atuais para os períodos de jejum no pré-operatório. Métodos: Um estudo prospectivo, cruzado e avaliador-cego foi feito com 17 voluntários saudáveis de ambos os sexos. Cada participante jejuou por 10 horas e foi submetido a uma ultrassonografia gástrica na fase basal, ingestão de 400 mL de água de coco ou 355 g de sanduíche de carne e avaliações gástricas ultrassonográficas foram feitas após 10 minutos e a cada hora até o estômago estar completamente vazio. Resultados: Na fase basal, todos os participantes estavam com o estômago vazio. Aos 10 minutos, o conteúdo gástrico [média + desvio-padrão (DP)] foi de 240,4 + 69,3 e 248,2 + 119,2 mL para alimentos líquidos e sólidos, respectivamente (p > 0,05). Os tempos médios de esvaziamento gástrico + DP foram de 2,5 + 0,7 e 4,5 + 0,9 horas para alimentos líquidos e sólidos, respectivamente (p < 0,001). Para a bebida, o estômago ficou completamente vazio em 59% e 100% dos sujeitos após duas e quatro horas; para o sanduíche, o estômago ficou completamente vazio em 65% e 100% dos sujeitos após quatro e sete horas, respectivamente. Conclusões: A dinâmica ultrassonográfica do volume gástrico para água de coco e sanduíche de carne resultou em tempos totais de esvaziamento gástrico maiores e menores, respectivamente, do que os sugeridos pelas diretrizes atuais para o jejum pré-operatório.

Bedside ultrasound measurement of gastric content and volume / 基础医学与临床

Perioperative pulmonary aspiration is a serious complication during general anesthesia .For patients with un-known gastric condition , there is no effective method for the noninvasive evaluation of gastric content and volume preop-eratively.Because of the portable and real-time detection, bedside ultrasound can significantly reduce the risk of periop-erative reflux and pulmonary aspiration , which makes preoperative gastric contents visualized and accurate .

Vida y obra de Abel Cetrángolo (1916 - 1977) / Life and work of Abel Cetrángolo (1916-1977)

Desde 1947 se inició el tratamiento específico de la tuberculosis que adquirió un valor inusitado, dado que el mismo modificó en el mundo entero el curso de la enfermedad tuberculosa. Roentgen desde 1895 nos mostró su ubicación en el pulmón, pero fue el laboratorio que permitió su diagnóstico y tratamiento, sucesivamente modificado con el transcurrir de los años. Abel Cetrángolo, como quien fuera su maestro y padrino de tesis, Andrés Arena entre nosotros, logró caracterizar al bacilo de Koch y en esa misma tesis nos enseñó el valor diagnóstico del contenido gástrico. Se distinguió por la seriedad de sus trabajos científicos tanto en Córdoba en la escuela de Gumersindo Sayago como en la Cátedra de Patología y Clínica de la Tuberculosis con la conducción de Raúl F Vaccarezza; fue un verdadero maestro para sus discípulos sentando bases valederas en sus conclusiones. Todo jefe de servicio debe trascender por lo que dejacientíficamente, pero también en la formación de médicos que puedan continuar en la profesión desde el punto de vista asistencial y docente con el ejemplo que él les legó.

Since 1947 the specific treatment of tuberculosis acquired an unused value, since it changed over the world the course of tuberculosis. Roentgen from 1895 showed us its location in the lung, but it was the laboratory that allowed its diagnosis and treatment, successively modified with the passing of the years. Abel Cetrángolo, and his former teacher and thesis godfather Andrés Arena among us, characterized the Koch bacillus and in that same thesis reinforced the value of gastric content. It was distinguished by the seriousness of his scientific works, both in Córdoba in Gumersido Sayago school and in the Department of Pathology and Clinical Tuberculosis headed by Raul F Vaccarezza, was a true master for his disciples sitting valid bases of conclusions. All service manager must transcend so scientifically leaves, but also in the training of doctors that can continue in the profession from the point of view clinical and teaching by example that he bequeathed them.

Qualitative and quantitative ultrasound assessment of gastric content / Avaliação qualitativa e quantitativa do conteúdo gástrico através da ultrassonografia

Summary Objective: Pulmonary aspiration of the gastric contents is one of the most feared complications in anesthesia. Its prevention depends on preoperative fasting as well as identification of risky patients. A reliable diagnostic tool to assess gastric volume is currently lacking. The aim of this study performed on volunteers was to evaluate the feasibility of ultrasonography to identify qualitative and quantitative gastric content. Method: A standardized gastric scanning protocol was applied on 67 healthy volunteers to assess the gastric antrum in four different situations: fasting, after ingesting clear fluid, milk and a solid meal. A qualitative and quantitative assessment of the gastric content in the antrum was performed by a blinded sonographer. The antrum was considered either as empty, or containing clear or thick fluid, or solids. Total gastric volume was predicted based on a cross-sectional area of the antrum. A p-value less than 0.05 was considered statistically significant. Results: For each type of gastric content, the sonographic characteristics of the antrum and its content were described and illustrated. Sonographic qualitative assessment allowed to distinguish between an empty stomach and one with different kinds of meal. The predicted gastric volume was significantly larger after the consumption of any food source compared to fasting. Conclusion: Bedside sonography can determine the nature of gastric content. It is also possible to estimate the difference between an empty gastric antrum and one that has some food in it. Such information may be useful to estimate the risk of aspiration, particularly in situations when prandial status is unknown or uncertain.

Resumo Objetivo: A aspiração pulmonar do conteúdo gástrico é uma das complicações mais temidas em anestesia. A sua prevenção depende do jejum pré-operatório e da identificação dos pacientes de risco. Não há um método diagnóstico que possa acessar o conteúdo gástrico a qualquer momento. O objetivo deste estudo realizado em voluntários foi fazer uma avaliação qualitativa e quantitativa do conteúdo gástrico utilizando a ultrassonografia. Método: O estudo foi realizado em 67 voluntários utilizando uma técnica já descrita de avaliação do antro gástrico, em quatro diferentes situações: jejum, após a ingestão de líquido claro, leite ou refeição sólida. Foi feita uma avaliação qualitativa e quantitativa do conteúdo gástrico por um radiologista que desconhecia o estado gástrico do voluntário. O antro foi considerado vazio, contendo líquido claro ou espesso, ou sólido. O volume total do estômago foi calculado com base na área seccional do antro. Um valor de p<0,05 foi considerado estatisticamente significativo. Resultados: Para cada tipo de conteúdo gástrico, as características ultrassonográficas do antro e de seu conteúdo foram descritas e ilustradas. A avaliação qualitativa pode distinguir um estômago vazio de outros com diferentes conteúdos. O volume gástrico calculado foi significativamente maior após a ingestão de qualquer alimento em comparação com o jejum. Conclusão: A ultrassonografia à beira do leito pode determinar a natureza do conteúdo gástrico. Também foi possível diferenciar um antro vazio daquele com algum volume. Essas informações podem ser úteis na determinação do risco de aspiração gástrica, principalmente se a condição gástrica é desconhecida ou incerta.

Comparison of Preoperative Gastric Contents between Gestational Diabetic and Normal Pregnant Women Undergoing Elective Cesarean Delivery / 대한마취과학회지

BACKGROUND: Delayed gastric emptying occurs frequently in diabetic patients. The aim of this study was to investigate preoperative gastric acidity and volume in parturients with gestational diabetes mellitus (GDM) undergoing elective cesarean delivery. METHODS: Twenty-five full term gravid women with GDM (GDM group) and another twenty-five without any complication (control group) were recruited. Before the anesthesia, a 14-F multiorifice nasogastric tube was inserted and the gastric contents were directly aspirated. RESULTS: There were no differences in the aspirated gastric pH and volumes between the groups (2.6 pH with 29.9 ml in the control group vs. 2.5 pH with 29.8 ml in the GDM group). The numbers of patients at-risk for aspiration, pH 25 ml in the two groups were similar (9/25, 36% in the GDM group, 7/25, 28% in the control group). CONCLUSIONS: Diabetes does not increase the risk of aspiration pneumonitis compared to the normal pregnant women in elective cesarean delivery.

The Effects of Preoperative Vaginal Misoprostol on Gastric Contents / 대한마취과학회지

BACKGROUND: The aim of this study was to evaluate the effect of vaginal misoprostol for operative hysteroscopy on preoperative gastric contents and the risk of acid aspiration pneumonitis. METHODS: Sixty-five patients undergoing operative hysteroscopy who received prophylactic vaginal misoprostol 200 microgram were assigned to the misoprostol group, and sixty-five gynecologic patients without premedication were assigned to the control group. After preoxygenation, a 14-F multiorifice nasogastric tube was inserted for direct aspiration under target-controlled propofol sedation. RESULTS: The mean pH value of gastric fluid was significantly higher in the misoprostol group (2.7 +/- 1.0) than the control group (1.9 +/- 0.7). The mean aspirated volume was (ml) 15.3 +/- 7.4 in the misoprostol group and 16.8 +/- 6.9 in the control group (P > 0.05). There were significantly less patients at high-risk (gastric fluid volumes > 25 ml and pH < 2.5) in the misoprostol group (8/65, 12.3%) than in the control group (18/65, 27.7%). Prophylactic vaginal misoprostol increases the preoperative gastric pH and reduces the number of at high-risk of acid aspiration pneumonitis. CONCLUSIONS: Therefore, vaginal misoprostol for outpatient hysteroscopy may have preventive effect on the acid aspiration pneumonitis.

Effects of Metoclopramide and Ranitidine on Preoperative Gastric Contents in Day-Case Surgery

This prospective, randomized, double-blinded study was performed to evaluate the effects of intravenous metoclopramide and ranitidine on preoperative gastric contents in outpatients receiving intravenous anesthesia for laparoscopic gynecologic surgery. Fifteen minutes before the induction of anesthesia, the Z-M group (n=20) received 50mg ranitidine and 10mg metoclopramide intravenously and the control group (n=20) received the same volume of normal saline. Before the surgery, a 14-F multiorifice nasogastric tube was inserted to aspirate the gastric contents of patients under sedation with propofol and midazolam. The mean pH values of the gastric fluid were 2.7+/-2.0 (SD) [median 1.6 (range: 1.2-7.2)] in the control group, and 6.1+/-1.9 [median 6.8 (range 1.4-7.8)] in the Z-M group. The mean aspirated volumes (mL) were 15.3+/-10.4 (SD) [median 11.0 (range: 5.0-44.0)] in the control group, and 6.9+/-10.0 (SD) [median 4.5 (range: 0-38.0)] in the Z-M group. There were significantly more high-risk (gastric fluid volumes > 25mL and pH < 2.5) patients in the control group (4/20, 20%) than in the Z-M group (1/20, 5%). In conclusion, intravenous prophylactic ranitidine and metoclopramide may be an easy and useful method to decrease the volume while increasing the pH of gastric contents, and therefore may reduce the number of patients at risk for aspiration pneumonitis in ambulatory laparoscopic procedures who receive an anesthesia.

Effects of Metoclopramide and Ranitidine on Preoperative Gastric Contents in Day-Case Surgery

This prospective, randomized, double-blinded study was performed to evaluate the effects of intravenous metoclopramide and ranitidine on preoperative gastric contents in outpatients receiving intravenous anesthesia for laparoscopic gynecologic surgery. Fifteen minutes before the induction of anesthesia, the Z-M group (n=20) received 50mg ranitidine and 10mg metoclopramide intravenously and the control group (n=20) received the same volume of normal saline. Before the surgery, a 14-F multiorifice nasogastric tube was inserted to aspirate the gastric contents of patients under sedation with propofol and midazolam. The mean pH values of the gastric fluid were 2.7+/-2.0 (SD) [median 1.6 (range: 1.2-7.2)] in the control group, and 6.1+/-1.9 [median 6.8 (range 1.4-7.8)] in the Z-M group. The mean aspirated volumes (mL) were 15.3+/-10.4 (SD) [median 11.0 (range: 5.0-44.0)] in the control group, and 6.9+/-10.0 (SD) [median 4.5 (range: 0-38.0)] in the Z-M group. There were significantly more high-risk (gastric fluid volumes > 25mL and pH < 2.5) patients in the control group (4/20, 20%) than in the Z-M group (1/20, 5%). In conclusion, intravenous prophylactic ranitidine and metoclopramide may be an easy and useful method to decrease the volume while increasing the pH of gastric contents, and therefore may reduce the number of patients at risk for aspiration pneumonitis in ambulatory laparoscopic procedures who receive an anesthesia.

No Difference in the pH of Gastric Contents between Moderate Obese and Lean Gynecological Patients / 대한마취과학회지

BACKGROUND: Two results have been conflict regarding the pH of gastric contents in obese and lean surgical patients. Obese patients have been considered to have lower pH of gastric contents than lean surgical patients since the study by Vaughan, whereas Harter reported no significant difference in the pH's of obese and lean surgical patients. The author wanted to investigate whether gastric content pH differs or not between obese and lean surgical patients aged from 20 to 60 years. METHODS: Forty patients scheduled for elective abdominal hysterectomy under general endotracheal anesthesia were studied. Group I (n = 20) was composed of lean patients whose body mass indices (BMIs) were between 20 and 25, whereas Group II (n = 20) was composed of obese patients whose BMIs were above 30. Every patient was fasted between 8 and 14 hours preoperatively. Within 10 minutes of endotracheal intubation, gastric contents were withdrawn with a 20 cc syringe connected to a 16F nasogastric tube placed in the stomach. pH and the incidences of pH <2.5, and pH <1.8 were compared. RESULTS: No significant difference in pH (P = 0.199) or in the incidences of pH less than 2.5 (P = 0.23) or 1.8 (P = 0.52) were observed between obese and lean patients. CONCLUSIONS: Obese and lean patients have similar fasting gastric pH's, as long as the obesity is not too severe (BMI under 40).

An examination of gastric content characteristics by naked eye to estimate the time of death.

The purpose of this research was to study the estimated time of death using naked eye examination of the gastric content characteristics. To our knowledge, such research has not been documented in Thailand. The study samples were collected from cadavers on which autopsies had been performed in the Department of Forensic Medicine Siriraj Hospital from April 2001 to December 2002. All 120 bodies had had accurately documented the time of death and relatives or witnesses who could give proper details of the subjects’ last meal. After the autopsy and examination of the gastric contents by naked eye, the findings were categorized into 5 groups as follows : Group 1 : Can specify the type of food. The interval of time from last meal to death was 0.25 – 3.00 hours : X = 1.20, SD = 0.74. Group 2 : Very thick contents and can identify the composition of food. The interval of time after last meal to death was 0.75 – 5.00 hours : X = 2.59, SD = 0.86. Group 3 : Very thick contents but cannot specify the type of food. The interval of time after last meal to death was 3.50 – 6.5 hours : X = 4.16, SD = 0.81. Group 4 : Mixed thick and watery contents and cannot specify the type of food. The interval of time after last meal to death was 3.50 – 5.50 hours : X = 4.69, SD = 0.65. Group 5 : Watery contents and cannot specify the type of food. The interval of time from last meal to death was 6.00 – 8.00 hours : X = 6.96, SD = 0.81. The results of this research may be useful for estimating the time of death (in addition to other factors, e.g. rigor mortis). There are some limitations to this study and therefore, further research is recommended.