Oral contrast for abdominal computed tomography in children: the effects on gastric fluid volume

Assessing Residual Gastric Fluid Volume after Administering Diluted Oral Contrast until One Hour Prior to Anesthesia in Children: An Observational Cohort Study

Background: Gastric fluid volume has been used as a surrogate marker for pulmonary aspiration risk in studies evaluating fasting protocol safety. This study measured residual gastric fluid volume in children using a protocol in which diluted oral contrast medium was administered up until one hour before anesthesia. Methods: This was a single-center prospective observational cohort trial of 70 children for elective abdominal/pelvic computed tomography (CT). Imaging was performed after diluted enteral contrast medium administration, beginning two hours before and ending at least one hour before induction. For each patient, gastric fluid volume was calculated using an image region of interest. The primary outcome measure was gastric fluid volume measured using the computed tomography image. Results: The median time from the end of contrast administration to imaging was 1.5 h (range: 1.1 to 2.2 h). Residual gastric volume, measured using CT was <0.4 mL/Kg in 33%; ≥0.4 mL/Kg in 67%; and ≥1.5 mL/Kg in 44% of patients. Residual gastric volumes measured using CT and aspiration were moderately correlated (Spearman's correlation coefficient = 0.41, p = 0.0003). However, the median residual gastric volume measured using CT (1.17, IQR: 0.22 to 2.38 mL/Kg) was higher than that of aspiration (0.51, IQR: 0 to 1.58 mL/Kg, p = 0.0008 on differences in paired measures). Three cases of vomiting were reported. No evidence of pulmonary aspiration was identified. Conclusions: Children who receive large quantities of clear fluid up to one hour before anesthesia can have a significant gastric residual volume.

An international multidisciplinary consensus statement on fasting before procedural sedation in adults and children

The multidisciplinary International Committee for the Advancement of Procedural Sedation presents the first fasting and aspiration prevention recommendations specific to procedural sedation, based on an extensive review of the literature. These were developed using Delphi methodology and assessment of the robustness of the available evidence. The literature evidence is clear that fasting, as currently practiced, often substantially exceeds recommended time thresholds and has known adverse consequences, for example, irritability, dehydration and hypoglycaemia. Fasting does not guarantee an empty stomach, and there is no observed association between aspiration and compliance with common fasting guidelines. The probability of clinically important aspiration during procedural sedation is negligible. In the post-1984 literature there are no published reports of aspiration-associated mortality in children, no reports of death in healthy adults (ASA physical status 1 or 2) and just nine reported deaths in adults of ASA physical status 3 or above. Current concerns about aspiration are out of proportion to the actual risk. Given the lower observed frequency of aspiration and mortality than during general anaesthesia, and the theoretical basis for assuming a lesser risk, fasting strategies in procedural sedation can reasonably be less restrictive. We present a consensus-derived algorithm in which each patient is first risk-stratified during their pre-sedation assessment, using evidence-based factors relating to patient characteristics, comorbidities, the nature of the procedure and the nature of the anticipated sedation technique. Graded fasting precautions for liquids and solids are then recommended for elective procedures based upon this categorisation of negligible, mild or moderate aspiration risk. This consensus statement can serve as a resource to practitioners and policymakers who perform and oversee procedural sedation in patients of all ages, worldwide.

Pulmonary aspiration during procedural sedation: a comprehensive systematic review

Background

Although pulmonary aspiration complicating operative general anaesthesia has been extensively studied, little is known regarding aspiration during procedural sedation.

Methods

We performed a comprehensive, systematic review to identify and catalogue published instances of aspiration involving procedural sedation in patients of all ages. We sought to report descriptively the circumstances, nature, and outcomes of these events.

Results

Of 1249 records identified by our search, we found 35 articles describing one or more occurrences of pulmonary aspiration during procedural sedation. Of the 292 occurrences during gastrointestinal endoscopy, there were eight deaths. Of the 34 unique occurrences for procedures other than endoscopy, there was a single death in a moribund patient, full recovery in 31, and unknown recovery status in two. We found no occurrences of aspiration in non-fasted patients receiving procedures other than endoscopy.

Conclusions

This first systematic review of pulmonary aspiration during procedural sedation identified few occurrences outside of gastrointestinal endoscopy, with full recovery typical. Although diligent caution remains warranted, our data indicate that aspiration during procedural sedation appears rare, idiosyncratic, and typically benign.

Should Oral Contrast Be Omitted in Patients with Suspected Appendicitis?

BACKGROUND

Acute appendicitis is one of the most common surgical emergencies. Our study evaluated patients given the diagnosis of appendicitis and reviewed their workup and clinical outcomes. We specifically focused on the use of oral contrast followed by appendectomy.

METHODS

We retrospectively reviewed all adult patients given an ICD-9 code for appendicitis at Northwestern Memorial Hospital between January 2000 and September 2010. Complication rates, time to the operating room, and length of hospital stay were compared between patients who received a CT scan and those who did not during the hospitalization for appendicitis.

RESULTS

Average time from Emergency Department to the operating room was found to be statistically longer for patients who underwent a CT scan (10 h: 3, 1548) versus those who did not (6 h: 2, 262) (p < 0.0001). There were 19 patients who had the complication of pneumonia and 4 patients who were diagnosed with acute respiratory distress syndrome postoperatively. Patients who underwent a CT scan and received oral contrast had a statistically higher number of both complications (p < 0.0001).

CONCLUSIONS

The use of oral contrast is not necessary for an accurate diagnosis of appendicitis and may be associated with higher complication rates, longer hospital stays, and poor outcomes.

Options and Considerations for Procedural Sedation in Pediatric Imaging

As pediatric imaging capabilities have increased in scope, so have the complexities of providing procedural sedation in this environment. While efforts by many organizations have dramatically increased the safety of pediatric procedural sedation in general, radiology sedation creates several special challenges for the sedation provider. These challenges require implementation of additional safeguards to promote safety during sedation while maintaining effective and efficient care. Multiple agent options are available, and decisions regarding which agent(s) to use should be determined by both patient needs (i.e., developmental capacities, underlying health status, and previous experiences) and procedural needs (i.e., duration, need for immobility, and invasiveness). Increasingly, combinations of agents to either achieve the conditions required or mitigate/counterbalance adverse effects of single agents are being utilized with success. To continue to provide effective imaging sedation, it is incumbent on sedation providers to maintain familiarity with continuing evolutions within radiology environments, as well as comfort and competence with multiple sedation agents/regimens. This review discusses the challenges associated with radiology sedation and outlines various available agent options and combinations, with the intent of facilitating appropriate matching of agent(s) with patient and procedural needs.

Enteral contrast in the computed tomography diagnosis of appendicitis: comparative effectiveness in a prospective surgical cohort

OBJECTIVE

Our goal was to perform a comparative effectiveness study of intravenous (IV)-only versus IV + enteral contrast in computed tomographic (CT) scans performed for patients undergoing appendectomy across a diverse group of hospitals.

BACKGROUND

Small randomized trials from tertiary centers suggest that enteral contrast does not improve diagnostic performance of CT for suspected appendicitis, but generalizability has not been demonstrated. Eliminating enteral contrast may improve efficiency, patient comfort, and safety.

METHODS

We analyzed data for adult patients who underwent nonelective appendectomy at 56 hospitals over a 2-year period. Data were obtained directly from patient charts by trained abstractors. Multivariate logistic regression was utilized to adjust for potential confounding. The main outcome measure was concordance between final radiology interpretation and final pathology report.

RESULTS

A total of 9047 adults underwent appendectomy and 8089 (89.4%) underwent CT, 54.1% of these with IV contrast only and 28.5% with IV + enteral contrast. Pathology findings correlated with radiographic findings in 90.0% of patients who received IV + enteral contrast and 90.4% of patients scanned with IV contrast alone. Hospitals were categorized as rural or urban and by their teaching status. Regardless of hospital type, there was no difference in concordance between IV-only and IV + enteral contrast. After adjusting for age, sex, comorbid conditions, weight, hospital type, and perforation, odds ratio of concordance for IV + enteral contrast versus IV contrast alone was 0.95 (95% CI: 0.72-1.25).

CONCLUSIONS

Enteral contrast does not improve CT evaluation of appendicitis in patients undergoing appendectomy. These broadly generalizable results from a diverse group of hospitals suggest that enteral contrast can be eliminated in CT scans for suspected appendicitis.

Violating traditional NPO guidelines with PO contrast before sedation for computed tomography

BACKGROUND

Administration of PO contrast within 2 hours before sedation for abdominal computed tomography (CT) is controversial because it violates American Society of Anesthesiologists guidelines that recommend 2 hours of fasting for clear fluids before sedation.

OBJECTIVE

This study aimed to review the administration of PO contrast for patients undergoing propofol sedation for abdominal CT and to evaluate the impact of violation of traditional 2-hour NPO guidelines on care.

METHODS

Sedation records were reviewed from January 2010 to October 2011 from all patients who received PO contrast within 2 hours of propofol sedation for abdominal CT. A control group of patients receiving intravenous contrast only before propofol sedation and abdominal CT was reviewed. Demographics, time between PO contrast administration and sedation, and amount of PO contrast were recorded. Outcome measures including success of sedation and adverse events (vomiting, suctioning, use of O₂ or advanced airway, unplanned admissions) were recorded.

RESULTS

Eighty-five patients received PO contrast within 2 hours before sedation for abdominal CT; 21 controls were identified. No differences in demographics or outcome measures were seen. No significant differences were seen in rates of interventions or adverse outcomes between groups. Median time between the successive PO contrast doses and propofol administration was 1.6 hours and 0.6 hours.

CONCLUSIONS

Administering oral contrast material within 2 hours of propofol sedation for abdominal CT in children seems to be relatively safe compared with those sedated after traditional NPO time frames.