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On-line version ISSN 1806-907X
Rev. Bras. Anestesiol. vol.54 no.1 Campinas Jan./Feb. 2004
Residual gastric volume and risk for pulmonary aspiration in children with gastroesophageal reflux. Comparative study*
Volumen gástrico residual y riesgo de aspiración pulmonar en niños con reflujo gastroesofágico. Estudio comparativo
Marcos Guilherme Cunha Cruvinel, TSA, M.D.I; Paulo Fernando Souto Bittencourt, M.D.II; José Roberto de Rezende Costa, TSA, M.D.III; Paulo Roberto Vieira Barbosa, M.D.IV
IAnestesiologista dos Hospitais Mater
Dei e Governador Israel Pinheiro (IPSEMG), Especialista em Clínica Médica
IIEspecialista em Pediatria pela SBP, Pediatra e Endoscopista dos Hospitais Mater Dei, HC-UFMG/Instituto Alfa de Gastrenterologia e Felício Rocho, Mestre em Pediatria pela UFMG
IIIAnestesiologista do Hospital Mater Dei e Gastrocenter, Mestre em Farmacologia pela UFMG
IVAnestesiologista do Hospital Felício Rocho
BACKGROUND AND OBJECTIVES: Children with
gastroesophageal reflux are often submitted to anesthesia for both diagnostic
and therapeutic procedures. They are considered as having delayed gastric emptying
and so anesthesia in this group is surrounded by special consideration, mostly
with regard to pulmonary aspiration. This study aimed at comparing residual
gastric volume of children with and without gastroesophageal reflux and at determining
if children with gastroesophageal reflux are at risk for pulmonary aspiration
METHODS: Participated in this study 38 children, physical status ASA I and II undergoing upper digestive diagnostic endoscopy. Children were distributed in two groups, according to the presence (group R) or absence (group N) of gastroesophageal reflux. All gastric content was collected and measured during the procedure.
RESULTS: There were 18 (47%) group R children and 20 (53%) group N children. Age, weight and fasting time were not significantly different between groups. In all patients, residual gastric volume was less then 0,4 ml.kg-1 and there were no significant differences between groups.
CONCLUSIONS: Children with gastroesophageal reflux were not at increased risk for pulmonary aspiration, as compared to children without reflux. Therefore, its prophylaxis would not be necessary.
Key Words: ANESTHESIA, Pediatric; COMPLICATIONS, pulmonary aspiration: DISEASES, gastroesophageal reflux
JUSTIFICATIVA Y OBJETIVOS: Frecuentemente,
niños con reflujo gastroesofágico tienen que ser sometidos a anestesia
para estudios diagnósticos y/o procedimientos quirúrgicos. Se
considera que el vaciamiento gástrico sea retardado en la molestia del
reflujo gastroesofágico pediátrico. Por tanto, la anestesia en
esos pacientes tiene aspectos peculiares, especialmente en lo que se refiere
al riesgo de aspiración pulmonar. El objetivo de este estudio es comparar
el volumen gástrico residual de niños con o sin reflujo gastroesofágico
y determinar si los niños con reflujo tienen, de hecho, riesgo aumentado
para la aspiración pulmonar del contenido gástrico durante la
MÉTODO: Participaron del estudio 38 niños, estado físico ASA I o II, sometidos a endoscópia digestiva alta diagnóstica. Los niños fueron divididos en dos grupos: grupo R, portadores de reflujo gastroesofágico y grupo N, sin reflujo gastroesofágico con endoscópia digestiva alta normal. Durante el procedimiento, todo el contenido gástrico fue aspirado y su volumen medido.
RESULTADOS: De los 38 niños estudiados, 18 (47%) fueron incluidos en el grupo R y 20 (53%) en el grupo N. No fueron constatadas diferencias significativas entre los dos grupos en lo que se refiere a la edad, al peso y tiempo de ayuno. En todos los pacientes, el volumen gástrico residual observado fue inferior a 0,4 ml.kg-1; y no hubo diferencias significativas entre los grupos.
CONCLUSIONES: En las condiciones de este estudio, el volumen gástrico residual no divergió entre los niños portadores, o no, de reflujo gastroesofágico. Por tanto, los niños con reflujo gastroesofágico no presentaron riesgo aumentado de aspiración pulmonar, cuando comparados a los niños sin reflujo gastroesofágico, pudiendo dispensar su profilaxis.
Gastroesophageal reflux is a disease affecting both adults and children (7% to 10%) 1. So, it is not unusual for children with this disease to be submitted to anesthesia for diagnostic and/or surgical procedures. Anesthesia in this group is surrounded by special consideration, mostly with regard to pulmonary aspiration. Pulmonary gastric content aspiration is for a long time considered a cause for morbidity and mortality in patients submitted to anesthesia 2,3. This study aimed at comparing residual gastric volume in children with and without gastroesophageal reflux and determining whether gastroesophageal reflux children are at increased risk for pulmonary gastric content aspiration during anesthesia.
After the Ethics Committee approval and parents' informed consent, participated in this study 38 children physical status ASA I and II, submitted to upper digestive diagnostic endoscopy. Exclusion criteria were esophageal, gastric or duodenal disorders, except gastroesophageal reflux, in addition to hormonal and renal disorders and congenital diseases. Children were divided in two groups: Group R - with gastroesophageal reflux; and Group N - without gastroesophageal reflux and with normal upper digestive endoscopy. Children referred for investigation of abdominal pain or vomiting and with normal endoscopic results were allocated to group N. Two patients referred for this same purpose had esophagitis and were included in Group R. Gastroesophageal reflux diagnosis of remaining Group R children was based on clinical presentation and additional tests, such as pH, scintigraphy, enhanced esophageal-gastric radiological investigation and upper digestive endoscopy itself when it clearly showed esophagitis. Fasting directions were given to children's tutors in a previous visit, according to table I. All children were submitted to general anesthesia with tracheal intubation and monitoring with precordial stethoscope, pulse oximetry and ECG. All gastric content has been aspirated and measured.
Fisher's Exact test was used to compare gender between groups. Student's t test was used to evaluate differences in age, weight, fasting time and residual gastric content. All results were considered significant for a significance probability below 5% (p < 0.05).
From 38 children enrolled in the study, 18 (47%) were included in Group R and 20 (53%) were included in Group N. One child who should belong to group N presented solid gastric content and the mother, after having initially stated that the child was on fasting, ended up reporting the non compliance with fasting directions. This child was, then, excluded from the study.
Mean Group R age was 47.7 months and mean Group N age was 55.5 months, without significant difference. Groups were also similar in mean weight (Group R: 15 kg and Group N: 18.4 kg). Mean fasting time for group R was 9.1 hours while for group N it was 9.6 hours, without statistically significant difference.
Residual gastric content for all patients was below 0.4 ml.kg-1. Group R has varied 0 to 0.38 ml.kg-1 (mean = 0.10 ml.kg-1) and Group N has varied 0 to 0.27 ml.kg-1 (mean = 0.09 ml.kg-1), again without significant difference between groups (Table II).
Preoperative fasting has not always been recommended and its requirement is directly related to pulmonary gastric content aspiration description and its consequences 3. Curiously, until late 19th Century, patients were oriented to drink tea two hours before anesthetic induction 3. The beginning of preoperative fasting recommendation is difficult to establish, but it started to become popular after 1946, when Mendelson has reported the relationship between food and aspiration during labor 2. As from this report, fasting for adequate gastric emptying started to be recommended to decrease the risk for aspiration pneumonia and it was reasonable that such recommendation would be widespread. The question then became the necessary fasting time for adequate gastric emptying.
However, to answer this question the volume to promote chemical pneumonitis had to be determined. Since Mendelson's description, it was already known that aspired fluid pH was critical for the development of the syndrome 3. Pulmonary injury severity increases with the acidity of the aspired fluid. So, the more acid, the lower the volume needed for pulmonary injury 4. Roberts et al. have published in 1974 an editorial defining that a residual gastric volume of 0.4 ml.kg-1 with pH below 2.5 would be enough for the development of the syndrome described by Mendelson 5. Several studies have attempted to confirm such values, based on Rhesus monkey studies. However, due to the impossibility of human studies and major differences among species, the extrapolation of animal studies to humans is potentially imprecise. Gastric volume and pH necessary to induce pneumonitis in humans have not been established and it is impossible to directly determine them. Roberts et al.'s definition has been accepted and has been the basis for most subsequent studies on the subject 3. It is important to remind that aspiration of all gastric content seems to be improbable, because the whole content would have to be regurgitated to the esophagus and totally enter lungs. For being the most widely used, although maybe imprecise, values of 0.4 ml.kg-1 with pH below 2.5 have been considered enough to cause aspiration pneumonitis.
Even after adequate fasting, some patients are at risk for the presence of residual gastric volume above 0.4 ml.kg-1, whom are called "full stomach" (Chart I) 6-11. In this group, unique mechanisms delay gastric emptying promoting high residual gastric volume, even after adequate fasting. In spite of some conflicting studies, delayed gastric emptying has been associated to gastroesophageal reflux disease in children 12-17.
In risk patients for pulmonary gastric content aspiration, specifically those with gastroesophageal reflux, anesthetic induction and emergence require additional care 3,18-20. Rapid sequence intravenous induction is the preferred method in such situations. Metochlopramide and H2 blockers would be indicated before induction. Intubation with awaken patients and preserved laryngeal reflexes is another alternative for those cases.
Intubation techniques with pulmonary gastric content aspiration prophylaxis are extremely useful and important for risk patients, and have resulted in major decrease in pulmonary aspiration and anesthetic morbidity and mortality 3. However, they may have disadvantages and even risks. The establishment of a venous access in awaken children is frequently time consuming, uncomfortable and stressing. In those patients, pre-oxygenation with 100% oxygen for some minutes is not always feasible and may promote additional stress. Succinylcholine bears the burden of malignant hyperthermia, in addition to other well-established side effects, such as bradyarhythmias, hyperkalemia and even asystole, among others 21. Rocuronium does not have these adverse effects, but in rapid sequence tracheal intubation doses (600 µg.kg-1) it has prolonged duration (46 minutes), making it less useful for short procedures 19. Metochlopramide and H2 blockers may promote side effects, such as extrapiramidal and neurpsychical symptoms, as well as bradycardia or histamine release 22,23. Tracheal intubation with awaken children and preserved laryngeal reflexes is also uncomfortable, difficult and stressful. For those reasons, such techniques should only be used in selected patients. Its use in patients with no risk for pulmonary aspiration, in addition to be unnecessary, may bring potentially avoidable morbidities.
So, it is clear that three conditions are necessary to promote aspiration pneumonitis 3:
1. Regurgitation (passive and clinically silent process) or vomiting (active process involving a complicated and coordinated series of reflexes);
2. Sufficient volume of regurgitated material should reach tracheobronchial tree;
3. Gastric content should be able to produce pulmonary injury.
Our study has evaluated a group of 18 children with well-established diagnosis of gastroesophageal reflux and has not found even one child with residual gastric content enough to expose them to pulmonary aspiration risk. Moreover, in comparing residual gastric content of these 18 children to those 20 children without reflux, no significant differences were found.
In the conditions of our study, residual gastric content has not differed in children with or without gastroesophageal reflux. So, we concluded that children with gastroesophageal reflux are not at an increased risk for pulmonary aspiration as compared to children without gastroesophageal reflux, with no need for prophylaxis.
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Dr. Marcos Guilherme Cunha Cruvinel
Address: Rua Simão Irffi, 86/301 - Bairro Coração de Jesus
ZIP: 30380-270 City: Belo Horizonte, Brazil
Submitted for publication February 18, 2003
Accepted for publication May 28, 2003
* Received from Departamentos de Anestesiologia e Endoscopia dos Hospitais Mater Dei e Felício Rocho, Belo Horizonte, MG