Gastric emptying and anaesthesia

Canadian Journal of Anesthesia/Journal canadien d'anesthésie - An understanding of factors which influence gastric emptying rate is important for anaesthetists. In the absence of pyloric...     

Gastric emptying and bezoars

Bezoars are conglomerates of undigested material in the stomach, which appear as a late complication of gastric surgery and are presumably related to secondary motility changes. We studied the gastric emptying of a technetium-99m-(Tc 99m) labelled solid meal in 10 patients who presented with a bezoar 1 to 20 years after vagotomy and pyloroplasty, vagotomy and antrectomy, vagotomy and gastrojejunostomy, or hemigastrectomy. The results were compared with the emptying data of operated patients without bezoars. The gastric retention of Tc 99m-labelled solids at 45, 75, and 105 minutes was 85 +/- 15 percent (mean +/- SD), 79 +/- 17 percent, and 65 +/- 24 percent, respectively. No differences were found when results were compared with those of operated patients without bezoars. We concluded that factors other than the gastric digestive phase are the main contributors to bezoar formation.     

Gastric emptying after head injury

Gastric emptying was measured in patients after head injury and compared with that of healthy volunteers using the rate of paracetamol absorption as an indicator of gastric emptying rate. There was a trend towards slower gastric emptying in the head injured patients, but the differences were not statistically significant.     

Gastric emptying of a solid meal

A simple, non-invasive technique for measuring gastric emptying of a solid meal in clinical practice is described. Cooked chicken liver labelled with a radioisotope is used. To establish the range of normal gastric emptying times 11 asymptomatic adults were studied. The effect of posture on solid emptying was also examined.     

Gastric emptying after minor gynaecological surgery

Gastric emptying was measured using the paracetamol absorption method in 30 patients immediately after a general anaesthetic for minor gynaecological surgery and in 10 female controls. Anaesthesia was induced with either propofol alone, propofol and alfentanil (4.5 micrograms.kg-1) or propofol and fentanyl (1.4 micrograms.kg-1) and maintained with intermittent propofol and 66% nitrous oxide in oxygen. Gastric emptying was delayed significantly in all patient groups when compared with volunteers. However, the delay in gastric emptying was similar in the three patient groups.     

Gastric emptying in trauma patients.

BACKGROUND/AIM: The aim of this study was to obtain quantitative data on gastric emptying following trauma. METHODS: In order to assess gastric emptying for early enteral feeding, we evaluated the absorption of an amino acid, L-[1-(13)C]phenylalanine, within 24 h of admission and 7 days later in 14 trauma patients (injury severity score 36 +/- 2). Following nasogastric administration of 100 mg L-[1-(13)C]phenylalanine, the plasma L-[1-(13)C]phenylalanine enrichment at 30 and 60 min and the expired (13)CO(2) for 1 h in the breath were used to measure the degree of gastric emptying. RESULTS: The plasma L-[1-(13)C]phenylalanine enrichment concentration at 30 min was 0.53 +/- 0.23 mmol/l during the first study and 2.46 +/- 0. 62 mmol/l during the second study (p = 0.006, a fivefold increase). The L-[1-(13)C]phenylalanine plasma level in historic controls was 4. 57 +/- 1.48 mmol/l. The percent of the dose oxidized and expired as (13)CO(2) in 1 h was 0.51 +/- 0.17 during the first 24-hour study compared to the second study of 3.37 +/- 0.68 (p = 0.0008) 7 days later (an over sixfold increase). The percent of the dose oxidized in 1 h in 37 normal historic controls was 7.08 +/- 0.33. CONCLUSION: These data indicate delayed gastric emptying with limited recovery in 1 week. We conclude that gastric feeding should not be employed, and the route for early nutritional intervention should be transpyloric for the trauma patient.     

Gastric emptying and clinical outcome after Roux-en-Y diversion

The results of 48 Roux-en-Y (RY) diversion procedures are reported: 41 were performed as secondary procedures and 7 as part of a primary operation for peptic ulcer. There was no operative mortality, but four patients developed temporary fistulae in the postoperative period and three patients required reoperation. Good clinical results were found when RY diversion was performed as a primary procedure or when the indication for operation was peptic ulceration. The overall results, however, were poor: 24 patients (50 per cent) felt that they had not benefited and 32 patients (67 per cent) remained in Visick grades III or IV. The main cause of failure was gastric stasis, especially of solid food. Gastric emptying studies were carried out after RY diversion in 22 patients, most of whom had symptoms of stasis. Emptying of liquids was found to be normal in most patients, but emptying of solids was delayed, the median t 1/2 for solids being 160 (75-370) min compared with 67 (50-85) min in DU patients. Bilious vomiting improved significantly after RY diversion, but 18 patients (38 per cent) complained of vomiting food and 32 patients (67 per cent) experienced postprandial distress or pain. Loss of the antral mill, vagotomy of the gastric remnant and, perhaps, resistance to gastric emptying by the Roux loop itself may together explain the delay in gastric emptying of solids after RY diversion.     

Gastric emptying and myoelectric activity following Roux-en-Y gastrojejunostomy

The purpose of this study was to compare gastric emptying and Roux myoelectric activity in a canine model. Four dogs underwent truncal vagotomy, antrectomy, and 40 cm Roux-en-Y gastrojejunostomy, with placement of serosal electrodes. Following recovery, gastric emptying was determined scintigraphically with a radiolabeled solid meal, and fasting and fed small-bowel myoelectric activity was obtained. Gastric emptying was markedly slowed compared to control unoperated animals (202 +/- 91 versus 46 +/- 12 min; P less than 0.05). Slow wave frequency declined in the Roux limb compared to the duodenum (14.2 +/- 0.4 versus 18.0 +/- .06 counts per minute; P less than 0.01). No gradient in slow wave frequency was observed in the Roux limb, although one animal was noted to have reversed propagation of slow waves in the proximal Roux limb. Migrating myoelectric complexes (MMCs) were coordinated between the Roux limb and jejunum distal to the enteroenterostomy, but not with the duodenum. Periodicity of the MMCs was different in the Roux limb and duodenum (98.6 +/- 6.3 versus 138 +/- 17.5 min; P less than 0.05). None of the animals converted to the fed myoelectric pattern with a 272 kcal meal (MMC periodicity in the Roux limb = 99 +/- 10 min postprandially, P = N.S.). These quantitative and qualitative alterations in myoelectric activity may contribute to the observed delay in gastric emptying following Roux-en-Y gastrojejunostomy.     

Gastric emptying of water in term pregnancy

BACKGROUND: Healthy nonpregnant patients may ingest clear liquids until 2 h before induction of anesthesia without adversely affecting gastric volume. The purpose of this study was to compare gastric emptying in term, nonlaboring pregnant women after ingestion of 50 ml water (control) with that after ingestion of 300 ml water. METHODS: Gastric emptying was assessed in healthy, nonobese, term pregnant volunteers using both serial gastric ultrasound examinations (n = 9) and acetaminophen absorption (n = 11) in a crossover study design. After an overnight fast, volunteers ingested 1.5 g acetaminophen and 50 or 300 ml water (assigned in random order) on two occasions separated by at least 2 days. Serial gastric antrum cross-sectional areas were determined using gastric ultrasound imaging, and the half-time to gastric emptying was calculated. Serial plasma acetaminophen concentrations were measured. Areas under the plasma acetaminophen concentration versus time curve, peak concentrations, and time to peak concentration for 50- and 300-ml ingestions were compared. RESULTS: Gastric emptying half-time was significantly shorter after ingestion of 300 ml water than after ingestion of 50 ml (24 +/- 6 vs. 33 +/- 8 min). There were no differences in acetaminophen areas under the curve at 60, 90, or 120 min, or in acetaminophen peak concentration. Time to peak concentration of acetaminophen was significantly shorter after ingestion of 300 ml water than after ingestion of 50 ml (25 +/- 12 vs. 41 +/- 19 min). CONCLUSIONS: Gastric emptying in healthy, term, nonobese, nonlaboring pregnant women is not delayed after ingestion of 300 ml water compared with that after an overnight fast.     

Gastric emptying of a light hospital breakfast

While intake of clear fluids 2–3 h before surgery is considered safe as it does not influence gastric content, it is not known if the same applies to a light breakfast meal. We therefore studied gastric emptying of a light breakfast in healthy, female volunteers without evidence of gastrointestinal motility disorders. The test meal consisted of one slice of buttered toast with jam, one cup of coffee without milk or sugar and one glass of pulp-free orange juice taken together with a paracetamol mixture. Using gastric ultrasonography, the stomach was identified without problems in all subjects, and gastric emptying curves using changes in gastric antral area and serum-paracetamol were obtained. Emptying of the fluid phase started immediately after intake of the meal. All subjects had solid particles in the stomach 120 min after the meal, 3 patients were considered empty after 180 min, 6 after 210 min and all after 240 min. The gastric antral area returned to fasting value significantly faster than the disappearance of solid particles; median 150 min versus 210 min; P =0.01. Our results show that in healthy subjects the stomach cannot be considered empty for solid particles the first 4 h after a light breakfast meal. To secure some safety limits, we suggest a 6-h mandatory preoperative fast after a light breakfast.     

Gastric emptying in the postpartum period.

We measured gastric emptying, using the technique of paracetamol absorption, in eight women on their first and third postpartum day. Gastric emptying was rapid and there was no difference between the first and third day in the time to peak plasma concentration of paracetamol. Six women returned after six weeks for a further study. Gastric emptying was still rapid but the metabolism of paracetamol appeared to be slower than that found during the immediate postpartum period. These findings suggest that fluid fasting guidelines in patients more than one day postpartum need not be different from those in non-pregnant patients.     

Gastric emptying after gastroplasty for morbid obesity

Gastric emptying was studied in 11 patients who had undergone gastroplasty for morbid obesity 6 to 8 months previously and in 22 normal controls without gastrointestinal disease. A dual isotope technique for measuring solid and liquid emptying was used. Liquid emptying was slower in patients than controls. The emptying of solid was initially faster, but was followed by a prolonged slow rate of emptying indicating retention of solid food in the proximal partitioned pouch. There was no correlation between the weight loss produced by the operation and rates of solid or liquid emptying. Unlike gastric bypass, the changes in gastric emptying produced by gastroplasty were relatively small and gastric emptying rates in patients overlapped considerably with the range of emptying rates found in control subjects. The success of the procedure may depend on the induction of satiety by the filling of the partitioned pouch.     

Gastric reflux and pulmonary aspiration in anaesthesia

Although aspiration is a relatively rare event during anaesthesia, it represent an important cause of anaesthesia related mortality and also of ventilator associated pneumonia in intensive care unit. The incidence of aspiration is markedly increased after trauma owing to the risk of recent ingestion of food, depression of consciousness and airways reflexes, and gastric stasis induced by raised sympathoadrenal tone. The factors which contribute to the likelihood of aspiration include the urgency of surgery, airways problems, inadequate depth of anaesthetic, use of the lithotomy position, gastrointestinal problems, depressed consciousness, increased severity of illness and obesity. Factors that predispose to aspiration pneumonia are: a gastric content with a pH less than 2.5 and a gastric volume of 0.4 ml kg-1; a reduction in lower oesophageal sphincter tone; a reduction of upper oesophageal sphincter tone and a not coordination between the pharyngeal muscle and the upper oesophageal sphincter tone during swallowing; and a depression of protective airway reflexes. Methods to minimize regurgitation and aspiration involve control of gastric contents (preoperative starvation is the method universal accepted), application of cricoid pressure and control of the airways.     

Gastric emptying and postprandial symptoms after Billroth II resection

Gastric emptying was studied in 18 symptomatic and 16 asymptomatic patients after Billroth II (BII) resection (without vagotomy) and the possible relationships between emptying and postprandial symptoms in these patients were assessed. The BII patients were compared with 20 nonoperated patients who had duodenal ulcer disease and 16 healthy subjects. Gastric emptying of two test meals (a semisolid porridge meal and a solid pancake meal) was measured with a radionuclide technique. The major difference between the BII patients and control subjects and duodenal ulcer patients was an increased rate of emptying of the semisolid meal in the first 5 minutes after meal consumption. The percentage of the meal remaining in the stomach at 5 minutes after completion was significantly less in the symptomatic (45.3% +/- 4.3%) than in the asymptomatic BII patients (79.4% +/- 2.6%). A positive correlation was demonstrated between the initial emptying rate of semisolids and the intensity of postprandial nausea (p less than 0.01), vomiting (p less than 0.05), and vasomotor symptoms (p less than 0.001). The duration of the lag phase for solid and semisolid meals was shorter in BII patients than in healthy subjects but was as short in nonoperated duodenal ulcer patients. The duration of the lag phase for solid food in the BII patients correlated positively with the score for postprandial epigastric pain (p less than 0.001). The rate of emptying of the solid meal was lower in symptomatic BII patients (28.1% +/- 3.6% per hour) than in asymptomatic patients (47.8% +/- 7.2% per hour) and correlated with the severity of postprandial fullness and nausea. The emptying of the solid meal was inversely related to the initial emptying rate of the semisolid meal (p less than 0.05). Therefore, the results of this study support the assumption that many of the postprandial symptoms occurring after BII resection reflect alterations in gastric emptying. Some of the emptying abnormalities present after BII resection may be related to duodenal ulcer disease rather than to the surgical procedure.