Gastric emptying after head injury

Population pharmacokinetics of phenytoin in critically ill children

The objective was to study the population pharmacokinetics of bound and unbound phenytoin in critically ill children, including influences on the protein binding profile. A population pharmacokinetic approach was used to analyze paired protein-unbound and total phenytoin plasma concentrations (n = 146 each) from 32 critically ill children (0.08-17 years of age) who were admitted to a pediatric hospital, primarily intensive care unit. The pharmacokinetics of unbound and bound phenytoin and the influence of possible influential covariates were modeled and evaluated using visual predictive checks and bootstrapping. The pharmacokinetics of protein-unbound phenytoin was described satisfactorily by a 1-compartment model with first-order absorption in conjunction with a linear partition coefficient parameter to describe the binding of phenytoin to albumin. The partitioning coefficient describing protein binding and distribution to bound phenytoin was estimated to be 8.22. Nonlinear elimination of unbound phenytoin was not supported in this patient group. Weight, allometrically scaled for clearance and volume of distribution for the unbound and bound compartments, and albumin concentration significantly influenced the partition coefficient for protein binding of phenytoin. The population model can be applied to estimate the fraction of unbound phenytoin in critically ill children given an individual's albumin concentration.

Gastrointestinal dysmotility: clinical consequences and management of the critically ill patient

Gastrointestinal dysmotility is a common feature of critical illness, with a number of significant implications that include malnutrition secondary to reduced feed tolerance and absorption, reflux and aspiration resulting in reduced lung function and ventilator-associated pneumonia, bacterial overgrowth and possible translocation causing nosocomial sepsis. Prokinetic agent administration can improve gastric emptying and caloric delivery, but its effect on nutrient absorption and clinical outcomes is, as yet, unclear. Postpyloric delivery of nutrition has not yet been demonstrated to increase caloric intake or improve clinical outcomes.

Disparate response to metoclopramide therapy for gastric feeding intolerance in trauma patients with and without traumatic brain injury

Patients with traumatic brain injury (TBI) have delayed gastric emptying and often require prokinetic drug therapy to improve enteral feeding tolerance. The authors hypothesized that metoclopramide was less efficacious for improving gastric feeding tolerance for trauma patients with TBI compared to trauma patients without TBI. A retrospective analysis was conducted of patients admitted to the trauma or neurosurgical intensive care unit who received gastric feeding from January 2006 to April 2008. Gastric feeding intolerance was defined by a gastric residual volume >200 mL or emesis with abdominal distension or discomfort. Patients with gastric feeding intolerance were given metoclopramide 10 mg intravenously every 6 hours, followed by a dose escalation to 20 mg, and then combination therapy with metoclopramide and erythromycin 250 mg intravenously every 6 hours if intolerance persisted. In total, 882 trauma patients (49% with TBI) were evaluated. TBI patients had a higher incidence of gastric feeding intolerance than those without TBI (18.6% vs 10.4%, P < or = .001). Efficacy rates for metoclopramide 10 mg, metoclopramide 20 mg, and metoclopramide-erythromycin were 55%, 62%, and 79%, respectively (P < or = .03). Metoclopramide failure occurred in 54% of patients with TBI compared to 35% of patients without TBI, respectively (P < or = .02), due to a greater prevalence of tachyphylaxis. Single-drug therapy with metoclopramide was less effective for TBI trauma patients compared to trauma patients without TBI. Combination therapy with erythromycin as first-line therapy for TBI trauma patients with gastric feeding intolerance is indicated if there are no contraindications or significant drug interactions.

To determine the effect of metoclopramide on gastric emptying in severe head injuries: a prospective, randomized, controlled clinical trial

To determine the effect of 8-hourly administration of 10 mg intravenous metoclopramide, over a 48-h period on gastric emptying in severe head injury (SHI), 22 patients were prospectively randomized (Glasgow Coma Score of 3-8) to receive 2 ml of intravenous metoclopramide or 2 ml of 5% saline 8-hourly for 48 h. Baseline and serial blood paracetamol absorption assays were performed at time (t) = 0, 15, 30, 45, 60, 90 and 120 min on day 0 and day 2. The area under the curve between the day 0 and day 2 was used to measure the degree of gastric emptying. In SHI, sequential doses of metoclopramide did not appear to improve gastric motility within subject comparisons (p = 0.65) and between subject comparisons (placebo p = 0.4 and drug p = 0.12). Metoclopramide has no significant prokinetic effect on gastric emptying in SHI patients when given in the early postinjury period.

Outcome of direct percutaneous endoscopic jejunostomy tube placement for nutritional support in critically ill, mechanically ventilated patients

PURPOSE

Gastrointestinal function is adversely affected in critically ill mechanically ventilated patients. The most common abnormality is delayed gastric emptying. Among the options for postpyloric feeds, direct percutaneous endoscopic jejunostomy (PEJ) provides a permanent, reliable, and direct access to the small bowel and can be used for full enteral feedings, thus eliminating the need for parenteral nutrition.

PATIENTS AND METHODS

All patients who underwent direct PEJ tube placement while mechanically ventilated in the intensive care unit (ICU) were evaluated. For each patient the following factors were identified: age, indication for ICU admission and PEJ placement, nutritional support before and after PEJ placement, calories received, complications, and outcome.

RESULTS

Seventeen patients underwent the procedure. All had successful placement of direct PEJ tube. There was a single complication. Within 24 hours of PEJ placement, 16 of 17 patients tolerated jejunal feedings. All patients progressed to their established nutritional goals. There were no cases of aspiration of enteral feedings. In the 16 patients, total parenteral nutrition (TPN) was not required once PEJ tubes were placed. Thirteen patients were discharged home or to a rehabilitation facility with jejunal feedings.

CONCLUSIONS

Direct PEJ placement is a safe and reliable device that can be successfully placed in critically ill, mechanically ventilated patients. With this procedure, all patients can meet their nutritional requirements and eliminate the need for TPN.

Intolerance to intragastric enteral nutrition in critically ill patients: complications and management

Compared with parenteral nutrition, early administration of enteral nutrition (EN) to critically ill patients improves clinical outcomes and reduces infection rates. Intragastric EN often is complicated by intolerance, as indicated by elevated volumes of aspirated gastric residuals. Conflicting data are available for the volume of residual that represents intolerance, but most clinicians use 150-200 ml to signify gastrointestinal motility dysfunction. Intolerance is associated with mortality. Data support an association between intragastric EN and aspiration pneumonia, but little information is available regarding the contributory effect of intolerance. Transpyloric migration of the feeding tube may facilitate tolerance but does not reduce the likelihood of aspiration pneumonia. Prokinetic agents (cisapride, erythromycin, metoclopramide) promote gastric emptying. Results of most studies are limited because patients did not receive or tolerated intragastric EN. Metoclopramide is the agent of choice for treating intolerance. Further studies are necessary before prokinetic drugs can be recommended for preventing intragastric EN-associated aspiration pneumonia.

The paracetamol absorption test: a useful addition to the enteral nutrition algorithm?

BACKGROUND

Enteral nutrition in critically ill patients given via the nasogastric route is often decreased or stopped because of large gastric residual volumes.

AIM

To assess the effect of continuing enteral nutrition in patients with an elevated gastric residual volume but normal gastric emptying by the paracetamol absorption test.

METHODS

The paracetamol absorption test was performed on all patients receiving enteral nutrition via a nasogastric tube who had a residual volume (assessed every 8 hours) of >150 ml or more than twice the hourly infusion rate. Patients were then divided into 2 groups according to the result of the test: Group 1 (n=8), normal gastric emptying; and Group II (n=24), abnormal gastric emptying. Group I continued to receive enteral nutrition. In Group II feeding was interrupted in 18 patients and prokinetic agents administered, while a subgroup of six patients continued to receive enteral nutrition without prokinetic agents. All patients were followed for evidence of delayed gastric emptying and aspiration.

RESULTS

Residual volumes were similarly elevated in both groups (p=0.25). Enteral nutrition was continued in Group I with no adverse effects. Prokinetic agents allowed enteral nutrition to be resumed in 88% of the 18 Group II patients. Enteral nutrition in the subgroup had to be stopped because of persistently elevated residual volumes.

CONCLUSION

The paracetamol absorption test may be normal in patients with relatively high gastric residual volumes. These patients may continue to receive enteral nutrition.

Sequential single doses of cisapride, erythromycin, and metoclopramide in critically ill patients intolerant to enteral nutrition: a randomized, placebo-controlled, crossover study

OBJECTIVE

To evaluate the comparative efficacy of enteral cisapride, metoclopramide, erythromycin, and placebo for promoting gastric emptying in critically ill patients with intolerance to gastric enteral nutrition (EN).

DESIGN

A randomized, crossover study.

SETTING

Adult medical intensive care unit at a university-affiliated private hospital and trauma intensive care unit at a university teaching hospital.

PATIENTS

Ten adult, critically ill, mechanically ventilated patients not tolerating a fiber-containing EN product defined as a single aspirated gastric residual volume >150 mL or two aspirated gastric residual volumes >120 mL during a 12-hr period.

INTERVENTIONS

Patients received 10 mg of cisapride, 200 mg of erythromycin ethylsuccinate, 10 mg of metoclopramide, and placebo as 20 mL of sterile water every 12 hrs over 48 hrs. Acetaminophen solution (1000 mg) was administered concurrently. Gastric residual volumes were assessed, and plasma acetaminophen concentrations were serially determined by TDx between 0 and 12 hrs to evaluate gastric emptying.

MEASUREMENTS AND MAIN RESULTS

Gastric residual volumes during the study were not significantly different between agents. No differences in area under the concentration vs. time curve or elimination rate constant were identified between agents. Metoclopramide and cisapride had a significantly shorter mean residence time of absorption than erythromycin (6.3+/-4.5 [SEM] mins and 10.9+/-5.8 vs. 30.1+/-4.5 mins, respectively [p<.05]). Metoclopramide (9.7+/-15.3 mins) had a significantly shorter time to peak concentration compared with erythromycin and placebo (60.7+/-8.1 and 50.9+/-13.5 mins, respectively [p<.05]). The time to onset of absorption was significantly shorter for metoclopramide vs. cisapride (5.7+/-4.5 vs. 22.9+/-5.7 mins [p<.05]).

CONCLUSION

In critically ill patients intolerant to EN, single enteral doses of metoclopramide or cisapride are effective for promoting gastric emptying in critically ill patients with gastric motility dysfunction. Additionally, metoclopramide may provide a quicker onset than cisapride.

Gastric emptying in head-injured patients

OBJECTIVE

Most patients with moderate to severe head injury (HI) initially do not tolerate enteral feedings. Intolerance to nasogastric feeding is also commonly observed after HI. Quantitative measurements of gastric emptying (GE), to determine a possible mechanism for intolerance to enteral feeding, are lacking.

METHODS

We prospectively evaluated gastric emptying half-time (GET1/2) of liquid meals in 35 patients with moderate to severe HI.

RESULTS

In comparison with 16 age-matched healthy control subjects (29.4 +/- 3.7 min), GET1/2 was significantly prolonged (57.2 +/- 20.8 min, p < 0.05) and abnormal in 80% of the HI patients. A prolonged GET1/2 and higher incidence of abnormal GET1/2 were observed in female patients, older patients, and patients with low Glasgow coma scale (GCS) scores, when compared with male patients, younger patients, and patients with high GCS scores. However, the differences for the means of GET1/2 and the incidences of abnormal GET1/2 between the subgroup patients were not significant (p > 0.05). In addition, significantly prolonged GET1/2 and higher incidence of abnormal GET1/2 (p < 0.05) were observed in patients with short injury duration, in comparison with patients with long injury duration.

CONCLUSION

Head injury can cause significant prolonged GE of liquid meals, especially in patients with short injury duration.

Double-blind, randomized study of the effect of cisapride on gastric emptying in critically ill patients

OBJECTIVES

To investigate the absorption of the gastrokinetic drug, cisapride, and effect of cisapride on gastric emptying in critically ill patients; and to assess the usefulness of clinical signs of gastric emptying.

DESIGN

Prospective, randomized, controlled study.

SETTING

Medical/surgical/trauma intensive care unit (ICU) in a university hospital.

PATIENTS

Twenty-seven consecutively enrolled patients, aged 18 to 65 yrs, with normal hepatic and renal biochemistry who were not receiving enteral nutrition and who had no contraindications to enteral nutrition. These patients were expected to stay in the ICU for at least 4 days.

INTERVENTIONS

Patients were randomized to receive either placebo or rectal cisapride, 60 mg initially followed by two doses of 30 mg at 8-hr intervals.

MEASUREMENTS AND MAIN RESULTS

Gastric emptying was estimated, using acetaminophen absorption on day 1 of the study. Placebo or cisapride was administered and a second acetaminophen absorption test for gastric emptying was carried out on day 2,24 hrs after the first test. Four patients were excluded because of incomplete data. Statistical analysis was performed, using the area under the acetaminophen absorption curve from 0 to 60 mins as the primary measure of gastric emptying. There was no significant change in the area under the acetaminophen absorption curve from 0 to 60 mins from day 1 to day 2 in patients who received placebo or cisapride. Using the combination of the time to maximum acetaminophen concentration (< or = 30 mins) with a maximum concentration (> 12 mg/L) to define "normal" emptying, on day 1, four of the 11 placebo patients had the "normal" gastric emptying, and by day 2, five patients fulfilled this criterion. Before administration of cisapride, four of the 12 patients fulfilled this criterion, whereas nine fulfilled the criterion after receiving cisapride. There was a large variation in gastric emptying from day 1 to day 2; a power calculation suggests that approximately 150 patients would have to be studied to determine the effect of cisapride. There was no correlation between gastric emptying and the volume of gastric aspirate or the presence of bowel sounds. Plasma cisapride concentrations 4 hrs after the third dose, during the second acetaminophen absorption test, averaged 53 ng/mL (range 20 to 111).

CONCLUSIONS

Rectal cisapride in the dose given achieved average plasma concentrations similar to those concentrations achieved in healthy subjects after 30 mg of cisapride rectally. There is a large variation in gastric emptying from one day to the next and large numbers of patients are required to determine if cisapride administration improves early gastric emptying in critically ill patients. The volume of gastric aspirate and the presence of bowel sounds do not correlate with gastric emptying.

Impaired gastric emptying in mechanically ventilated, critically ill patients

OBJECTIVE

To measure gastric emptying in critically ill patients using an acetaminophen absorption model and determine which variables are associated with impaired gastric emptying.

DESIGN

A prospective, cohort study.

SETTING

A medical/surgical ICU at a tertiary care hospital: Hamilton General Hospital, Hamilton, Ontario.

PATIENTS AND PARTICIPANTS

We recruited 72 mechanically ventilated patients expected to remain in the ICU for more than 48 h. Our results were compared to those in healthy volunteers.

INTERVENTION

Within 48 h of admission to the ICU, 1.6 g acetaminophen suspension were administered via a nasogastric tube into the stomach. Blood samples were drawn a t = 0, 30, 60, 90, and 120 min for measurement of plasma acetaminophen levels determined by the enzymatic degradation method.

MEASUREMENTS AND RESULTS

Maximal concentration of acetaminophen was 94.1 (75.3) mumol/l compared to 208.4 (33.1) mumol/l in a control population (p < 0.0001). The time to reach the maximal concentration was 105 min (60-180) compared to 30 min (15-90) in controls (p < 0.0001). The area under the time-acetaminophen concentration curve t = 120 was 9301 (7343) mumol/min per l compared to 11644 (1336) mumol/min per l in the controls (p = 0.28). The variables associated with delayed gastric emptying were age, sex and use of opioids for analgesia and sedation.

CONCLUSIONS

Gastric emptying is delayed in critically ill patients. The important consequences of this phenomenon include intolerance to enteral nutrition and gastric colonization. Strategies to minimize the use of narcotics may improve gastric emptying. Studies to examine the effect of gastrointestinal prokinetic agents on gastric emptying are needed.

Effect of erythromycin on gastric motility in mechanically ventilated critically ill patients: a double-blind, randomized, placebo-controlled study

OBJECTIVE

To document the action of erythromycin on gastric emptying and motility in mechanically ventilated patients.

DESIGN

Crossover, double-blind, randomized, placebo-controlled study.

SETTING

General intensive care unit in a university hospital.

PATIENTS

Ten patients, mechanically ventilated, in a stable hemodynamic condition.

INTERVENTIONS

Erythromycin (200 mg i.v. over 30 mins) and placebo were infused at mid-morning, on two consecutive days, in a random order. Pressure changes in the gastric antrum were recorded by means of a multi-lumen manometric tube (perfused catheter technique) over a period of 300 mins, beginning with the institution of the erythromycin or placebo infusion. Gastric emptying was simultaneously assessed by the kinetics of the absorption of acetaminophen delivered into the stomach (1 g with 20 mL of water) immediately before the infusion.

MEASUREMENTS AND MAIN RESULTS

Motility was quantified by determining the number of contractions, the amplitude of contractions, and the Motility Index (Motility Index = natural logarithm [sum of amplitude x number of contractions] + 1). Comparison between placebo and erythromycin was made for the first hour after the infusion and for the whole recording session. The maximal acetaminophen concentration, the time to reach the peak acetaminophen concentration, and the area under the concentration-time curve at 60 mins were obtained from serial determinations of plasma acetaminophen concentrations. Compared with placebo, the mean number of contractions (104 +/- 34 vs. 5 +/- 8; p = .003), the mean amplitude of contractions (52 +/- 16 vs. 20 +/- 17 mm Hg; p = .005), and the Motility Index (13.06 +/- 0.95 vs. 4.45 +/- 3.54; p = .004) were significantly increased during the first hour after erythromycin infusion compared with placebo. Number of contractions (p = .017) and Motility Index (p < .001) after erythromycin infusion remained significantly higher when values throughout the whole recording session were considered. The following data were noted after erythromycin was infused: a) the time to reach the peak acetaminophen concentration was shorter (32 +/- 8 vs. 171 +/- 93 mins; p = .007); b) the maximal acetaminophen concentration was higher (22.09 +/- 6.23 vs. 5.38 +/- 3.80 micrograms/mL; p = .007); and c) the area under the concentration-time curve at 60 mins increased markedly (730 +/- 269 vs. 72 +/- 42 micrograms/min/mL; p = .002) as compared with placebo.

CONCLUSION

In mechanically ventilated patients, intravenous erythromycin (200 mg over 30 mins) increases indices of antral motility and accelerates gastric emptying as assessed by the kinetics of acetaminophen absorption.

Gastric emptying following brain injury: effects of choice of sedation and intracranial pressure

OBJECTIVE

To compare the effects of opioid and non-opioid sedation on gastric emptying.

DESIGN

Prospective, randomized trial.

SETTING

University teaching hospital ICU.

PATIENTS

21 brain injured patients requiring sedation, mechanical ventilation and intracranial pressure (ICP) monitoring for > 24 h.

INTERVENTIONS

Patients were randomized to receive infusions of either morphine plus midazolam (M), or propofol (P). Gastric emptying was assessed by the paracetamol absorption technique and by residual volumes following a 200 ml test feed.

MEASUREMENTS AND RESULTS

Pre-sedation Glasgow Coma Score, mean ICP and the presence of bowel sounds were noted. Plasma concentrations of paracetamol were measured over 3 h following a 1 g gastric dose. There were no differences in median peak paracetamol concentration (M, 18.5 versus P, 20.8 mg/l), median time to peak concentration (M, 20 versus P, 25 min), median area under the concentration-time curve (AUC), or in the median residual volumes at 1 h (M, 14 versus P, 10.5 ml) and 2 h (M, 5 versus P, 3 ml). In patients with ICP > 20 mmHg, paracetamol concentrations were lower (p < 0.05), and AUC after 30 min was lower (165 mg.min/l versus 411 mg.min/l, p = 0.023). Mean ICP was correlated with AUC (Kendall rank p = 0.027). Gastric emptying did not correlate with initial Glasgow Coma Score or presence of bowel sounds.

CONCLUSIONS

Gastric emptying is not improved in patients with brain injury by avoiding morphine (1-8 mg/h) in the sedative regimen. Intracranial hypertension is associated with reduced gastric emptying.

Gastric emptying in patients the day after cardiac surgery

Fourteen adults underwent cardiac surgery with a standard anaesthetic technique. Prior to surgery and the day after surgery, gastric emptying was determined using the paracetamol absorption technique. Results from 13 patients were available for analysis. The mean time to reach the maximum plasma concentration was 14.1 min (SEM 2.1) pre-operatively and 225.4 min (SEM 42.3) postoperatively. The mean maximum concentration was 23.7 mg.l-1 (SEM 1.9) pre-operatively and 5.1 mg.l-1 (SEM 0.8) postoperatively. The area under the curve (0-60 min) was 892 mg min.l-1 (SEM 57) pre-operatively and 131 mg min.l-1 (SEM 25) postoperatively. The differences between pre- and postoperative values were highly significant for all these three measurements. We conclude that gastric emptying is markedly delayed the day after elective cardiac surgery.

Gastroduodenal dysfunction and bacterial colonisation of the ventilated lung

The source of ventilator-associated pneumonia (gastric or oropharyngeal flora) remains controversial. We investigated the source of bacterial colonisation of the ventilated lung in 100 consecutive intensive-care patients. Gram-negative bacilli were isolated from the lower respiratory tract in 19 patients. Bacteria isolated from the stomach contents either previously or at the same time were identical to lower respiratory isolates in 11 patients. No gram-negative oropharyngeal isolate was identical to a lower respiratory tract isolate. Gastric bacterial overgrowth with gram-negative bacilli was associated with the presence of bilirubin in the stomach contents. Detectable bilirubin was also associated with subsequent acquisition of gram-negative bacilli in the lower respiratory tract. Only 5 gastric aspirate specimens with pH < 3.5 contained gram-negative bacilli. These results establish a relation between duodenal reflux and subsequent bacterial colonisation of the lower respiratory tract. Restoration of normal gastroduodenal motility might help prevent pneumonia in intensive-care patients.