Jan2010.html

 

University of Virginia Health System

Nutrition Support E-Journal Club

January-February 2010

 

 

  

Greetings,

Charlottesville traditionally enjoys relatively mild winter weather, but this year we entered the season with gusto - 2 feet of snow.  This kind of weather may be routine in some parts of the world, but for those of us that live below the Mason-Dixon Line, it generally exceeds the resources available for snow removal and salting.  The last vestiges of December snow had nearly melted when we were blessed with another round of snowstorms that closed schools and made work commutes slow and potentially hazardous.  Despite the weather challenges and a busy inpatient service, we made time for journal club in January, and returned to the topic of residual volumes once again.            

January Citation: 

Juvé-Udina ME , Valls-Miró C, Carre˜no-Granero A, et al.  To return or to discard? Randomised trial on gastric residual volume management. Intensive Crit Care Nurs 2009;25:258-267.

Summary: 

This was a prospective, randomized, non-blinded study that investigated the effects of returning gastric residual volumes (GRV) to the patient after they were checked versus discarding them in 125 adult critically ill patients.  The primary outcomes measured were GRV and gastric emptying delays.  Additional outcomes measured included whether reintroduction of GRV increased the incidence of feeding tube obstruction, pulmonary aspiration episodes, intolerance episodes (nausea, vomiting, diarrhea and abdominal distension), enteral feeding delays, hyperkalemia episodes, hyperglycemia episodes, and discomfort episodes, when compared to the discarding group.  The study was conducted in a single medical-surgical intensive care unit in a university hospital over 1 year.  Patients were prospectively monitored for nausea, vomiting, abdominal distension, diarrhea and pulmonary aspiration (by using glucose strips to check pulmonary aspirates).

The protocol for the study was:

  • GRV were checked q 6 hours via a 60 mL syringe over 48 hours of feeding.
  • No position changes were performed during the GRV controls.
  • All were kept with backrest elevation > 30 degrees.
  • GRV up to a maximum of 250 mL per check would be re-instilled to patients in the return (intervention) group.
  • If the GRV obtained from aspiration was > 250 mL, any surplus over 250 mL was discarded. Gastric emptying delay was defined as the difficulty in maintaining GRV within safe limits--defined as GRV below 5 mL/kg. Based on the "available evidence" (a pediatric study), GRV was categorized as: Light GED (151-250 mL/6 hours), Moderate GED (251-350 mL/6 hours) or Severe GED (>350 mL/6 hours).

Feeding delays in patients were defined as > 20% difference in the amount of feeding prescribed and the amount administered/ 24 hours.  Enteral formula was provided via continuous pump delivery through a 16 Fr salem-sump type tube.

EN was temporarily withheld if any of the following conditions were present:

  • GRV > 500 mL
  • Vomiting
  • Need of radiological or surgical procedures
  • Diarrhea for more than 48 hours.

Inclusion and Exclusion Criteria were:

Inclusion criteria:  patients admitted to the ICU, > 18, hemodynamically monitored, on enteral (EN) or parenteral nutrition (PN), all of them needing GRV controls due to their condition and treatment, with a length of stay estimated at > 48 hours.

Exclusion criteria: patients connected to an intermittent gastric aspiration system because of paralytic ileum, bowel obstruction, gastric fistula or gastric surgery.

Major Results reported by authors:

Analysis was completed on 61 patients in each group; 2 patients in the intervention arm and 1 assigned to the control group were not included in the final analysis due to length of stay or protocol errors.  The baseline characteristics of the groups had no significant differences at randomization.

Summary of results:

  • There were no significant differences in the mean GRV (49 vs 58 mL study vs control) between the groups. The lack of difference persisted after adjustment for: hyperglycemia, prokinetic medications and medication that may delay gastric emptying (opiates, atropine, barbiturates and neuromuscular blocking agents).
  • Incidence and severity of delayed gastric emptying episodes (GRV > 150mL) were significantly lower in the intervention group.
  • No differences were found between groups in the mean prescribed volume or the administered EN volume (1296mL vs 1291mL intervention vs control respectively)
  • No tube blockage or accidental extubations occurred.
  • Fluid balance and serum electrolyte outcomes were comparable in both groups, including potassium.
  • Hyperglycemic episodes were significantly more frequent in the intervention group (1352 intervention vs 1376 control, p = 0.001).
  • Complication rates were minimal and not different between the groups for nausea (0 both groups), emesis (1 each group) and pulmonary aspiration and insignificant for vomiting.

Author's Conclusions:

The authors concluded that this study supports the recommendation to reintroduce up to up to 250 mL gastric aspirate every 6 hours in critically ill patients to procure a more physiologic gastric content without increasing the risk of severe potential complications while controlling for glycemia.

Evaluation:

Positive aspects of this study include that patients were randomized into groups, and that the position of the tip of the feeding tube was assessed by radiograph every 24 hours.  The study was not conducted in a double-blind fashion, which introduces some chance of bias, but it is generally not practical to conduct such a study in a blinded fashion.

Our group felt that the primary limitations of this study include the short duration of the study (48 hours), and the limited data to support the use of GRV below 5mL/kg as an accurate surrogate marker of gastric emptying delay.  Additionally, the use of glucose testing of tracheal secretions is not a sensitive, or specific, indicator of pulmonary aspiration of GI contents.  Other considerations that the group discussed were the lack of information about how calorie needs were assessed, and no documentation regarding possible differences in prokinetic medications between groups.  The authors do mention that they controlled for prokinetic use when analyzing differences in GRV between groups.

A practical consideration is the fact that 16 Fr feeding tubes were used in this study.  Checking GRV through a large bore tube (16 Fr) did not increase tube occlusion over 48 hours, but this is not necessarily good evidence to suggest that checking/reinfusing GRV through smaller bore feeding tubes won't contribute to tube clogging.

Addendum: Just as we were loading this to our website, the authors replied to our email and reported that most patients were fed 25 calories/Kg, with some patients receiving up to 30 calories/Kg.  Additionally they conveyed that 24 patients received parenteral nutrition concurrent with EN (10 in reinfusion group, 14 in control).

Our Take Home message:

This study suggests that re-instillation of GRV up to 250 mL does not appear to compromise feeding tolerance or gastric emptying.  The finding that re-instillation of GRV appeared to reduce the incidence of delayed gastric emptying is worthy of further study.  One last consideration is that, in an era of staggering health care costs and lack of good evidence to support the checking of GRV (more evidence to the contrary, in fact), future studies should perhaps focus on determining the efficacy of checking GRV in the first place. If the practice of checking GRV is not helpful, or is detrimental, then nursing time would be better spent in activities other then checking and re-infusing gastric contents.

Other News:

Check out the full schedule of webinar programs at:

     http://www.healthsystem.virginia.edudh/webinars.html

  • February 23: Nutritional Impactof GI Surgery--Carol Parrish, MS, RD
  • March 9:The Ins and Outs of GI Fistulas--Kate Willcutts, MS, RD, CNSD

See the latest Practical Gastroenterology articles:

Available at: http://www.healthsystem.virginia.edu/pub/digestive-health/nutrition/resources.html

Joe Krenitsky MS, RD

Carol Rees Parrish MS, RD

PS - Please feel free to forward this on to friends and colleagues.