Enteral Nutrition and Cardiovascular Medications in the Pediatric Intensive Care Unit

Enteral Nutrition and Cardiovascular Medications in the Pediatric Intensive Care Unit

King, Wendalyn

ABSTRACT. Background: Enteral nutrition has multiple benefits for critically ill patients. However, the administration of enteral nutrition to patients requiring medications for cardiovascular support is controversial secondary to concerns of altered splanchnic perfusion. The objective of this study is to evaluate the tolerance of enteral nutrition in pediatric patients receiving cardiovascular medications. Methods: This was a retrospective chart review of patients admitted to the pediatric intensive care unit at Children’s Healthcare of Atlanta at Egleston in a 1-year period. Patients were eligible for the study if they received enteral nutrition during or within 24 hours of requiring continuous infusion of dopamine, dobutamine, epinephrine, norepinephrine, or neosynephrine. Results: Fifty-five admissions (52 patients) met study criteria. Patients ranged in age from 1 month to 20 years old. Although a large number (71%) of patients experienced at least 1 feeding interruption, the majority (70%) of reasons cited for stopping or slowing feedings were not related to gastrointestinal (GI) tolerance. Only 29% of patients had feedings held for perceived intolerance. Vomiting was the most often-cited reason for these interruptions. Constipation was reported in 36% of patients but cited only 4 times as a reason for feeding interruption. Four patients exhibited evidence of GI bleeding. This bleeding was considered clinically insignificant in 2 patients and appeared unrelated to enteral feedings in the others. Conclusions: This study suggests that many pediatric patients receiving cardiovascular medications tolerate enteral nutrition without adverse events. Further prospective studies are needed to determine whether enteral nutrition can consistently benefit these critically ill pediatric patients. (Journal of Parenteral and Enteral Nutrition 28:334-338, 2004)

Nutrition support is important for critically ill patients, and enterai nutrition is recognized as an acceptable, if not preferred, method of delivery. Multiple benefits have been ascribed to enterai nutrition, compared with parenteral nutrition, including maintenance of gut mucosal integrity, reduced risk of infection, and reduced cost.1-7 Intolerance of enterai nutrition has also been well described.5,6,8,9 Common presentations of feeding intolerance include high gastric residuals, constipation, vomiting, and abdominal distention.

Intolerance of enterai nutrition in the critically ill may be due in part to alterations in gastrointestinal motility secondary to the underlying disease process or to medication administration. Two classes of medications commonly administered in the intensive care unit that cause alterations in gut motility are benzodiazepines and narcotics. These drugs are used frequently to provide sedation and analgesia. Medications to support cardiovascular function are also frequently used in critically ill patients. The effects of these medications on the gastrointestinal system are still under investigation. Concerns regarding catecholamine-induced splanchnic vasoconstriction and inhibition of gut motility have led to controversy surrounding the provision of enterai nutrition to patients requiring cardiovascular support. This study explores the hypothesis that the use of cardiovascular medications is not associated with an increase in feeding intolerance or complications.

MATERIALS AND METHODS All study subjects were patients admitted to the pediatric intensive care unit (PICU) at Children’s Healthcare of Atlanta at Egleston, a tertiary care pediatrie center, during 1999. The institutional review board approved the study. The PICU is a mixed medical-surgical unit. Patients admitted to the general surgery and trauma services were excluded from the study because decisions regarding nutrition in these patients are made by the surgical, rather than critical care, staff. Pediatric critical care physicians, assisted by hospital dieticians, made all decisions regarding nutrition for PICU patients admitted to the medical service. Six trauma patients, all of whom had traumatic brain injury as their primary pathology, were managed by the pediatrie critical care service and were included in the study group. Patients were entered into the study if they received both enterai feedings and cardiovascular medication(s) within the same 24-hour period. For the purpose of this study, cardiovascular medication was defined as continuous infusion of dopamine, dobutamine, epinephrine, norepinephrine, or phenylephrine. A total of 733 PICU admissions were reviewed. Of these, 55 admissions, representing 52 patients, met the stated criteria for enrollment in the study. Three patients had 2 PICU admissions each, during which they met study criteria. These patients were included only once when evaluating patient demographics, but each admission was counted separately for the purpose of evaluating feeding-related complications and feeding tolerance.

Enteral nutrition consisted of age-appropriate, commercially available formula, usually provided as a continuous infusion through a feeding tube, except in the case of 6 patients able to take oral nutrition. Three of the tube-fed patients were fed intragastrically; the remaining 3 patients had nasojejunal feeding tubes. For each patient, the formula used and goal-feeding rate (based on calculated caloric requirements) were determined by the PICU physician in consultation with the dietitian. Initiation and titration of cardiovascular medications was carried out at the discretion of the PICU physician to meet individual-patient determined goals for hemodynamic parameters. A standardized data sheet was used to collect information on patient age, sex, diagnosis, feeding route, formula used, cardiovascular medication administration, maximum dose of cardiovascular medication required, narcotic and benzodiazepine administration, vomiting, constipation, interruption of feedings, reasons given for interrupting feedings, and any gastrointestinal complications. Data were collected from the time of initiation of feedings until the patient either reached goal feedings for a period of 7 consecutive days or was discharged from the PICU.

RESULTS

Study patients (27 males and 25 females) ranged in age from 1 month to 20 years. Forty-four (85%) of these 52 patients survived to discharge from the PICU. All required cardiovascular medications during their PICU stay. Dopamine was the most commonly used cardiovascular medication; all patients except 5 received either dopamine alone or dopamine in combination with another agent. Of note, only 3 of these patients received “low-dose” dopamine (

Six of the 55 patients in the study group were able to tolerate oral food or liquid throughout their PICU stay, and this was their sole source of enterai nutrition. One of the 6 was allowed sips of clears in addition to receiving parenteral nutrition; the other 5 either received clear liquids and advanced to a regular diet or received a regular diet throughout their PICU stay. Of these 6 patients, 1 received dobutamine alone for cardiac dysfunction after heart transplant. The patient receiving clear liquids plus parenteral nutrition was receiving lowdose dopamine (maximum dose 3 µg/kg/min). The remaining 4 patients were treated with a combination of dopamine and norepinephrine for sepsis-induced hypotension. The other 49 study patients were supported by tube feedings.

Four study patients exhibited evidence of gastrointestinal bleeding. Two of these patients had clinically insignificant, heme-positive stools. The other 2 had underlying coagulopathy and more extensive bleeding. There were no other serious gastrointestinal complications.

Thirty-nine of the 55 patients (71%) had their enterai feedings held at least once, for a total of 111 feeding interruptions (mean 2.8 interruptions per patient, range 1-6). A total of 118 reasons were cited for stopping or slowing the rate of feedings (occasionally more than 1 reason was cited). The most common reason for feeding interruption was airway management. For 12 of 55 patients (22%), feedings were held only for procedures (airway management, central line placement, etc) or for transport from the PICU to radiology or the operating room. These nongastrointestinal (GI)-related reasons accounted for 82 of 118 (70%) reasons cited for interrupting feedings. Another 16 of 55 patients (29%) experienced feeding interruption for reasons related to perceived feeding intolerance (vomiting, abdominal distention, high gastric residuals, constipation, or diarrhea). These GI-related cases accounted for only 30 of 118 (25%) reasons cited for interrupting feedings. see Figure 1.

Vomiting was the most commonly cited GI-related reason for interruption of feedings. Vomiting occurred in 12 of 55 patients (22%) and was cited 15 of 118 (13%) times as the reason for interrupting feedings. Twenty of 55 patients (36%) were treated for perceived constipation; all of these patients were receiving both benzodiazepines and narcotics at the time that constipation was noted. However, constipation was noted only 4 times as a reason for stopping feedings. Table II delineates the reasons for feeding interruptions.

DISCUSSION

Although the role of enterai nutrition in the critically ill continues to gain support, the safety and tolerance of enterai feedings during infusion of cardiovascular medications has not been established in the intensive care setting. Several studies looking at the effects of catecholamine infusions on gut motility,10,11 blood flow,12,13 and luminal pH12,14 have been published. Results of these studies varied, depending on type and dose of medication used. The impact of enterai feedings, either alone or in combination with catecholamines, was not addressed. Two other studies8,15 found the administration of vasoactive drugs to be a leading reason for the underprescription or withholding of enterai nutrition in adult intensive care unit (ICU) patients, although reasons for this behavior were not delineated. Clinical studies of enterai nutrition in pediatrie patients,4 pediatrie ECMO patients,1 and adult postoperative cardiac surgery patients,16 all of which included patients receiving cardiovascular medications, report no enterai feeding-related complications. None of these studies, however, looked at cardiovascular medication administration as an independent variable in addressing feeding-related complications or feeding intolerance.

The purpose of this study was to examine and report the experience in 1 PICU with patients who received enterai feedings while requiring cardiovascular medication support. Overall, these patients tolerated enterai nutrition without significant complications. The reasons given for interruption of feedings for perceived intolerance are similar in this study to those reported in other ICU studies in which rates of feeding intolerance ranged from 15% to 63%.1,8,9,15 Likewise, the data collected in this retrospective study are comparable to that collected on a subset of 97 pediatric patients in the same ICU over the past year (unpublished data). These data are part of a prospective study of a feeding protocol in which 23% of feeding interruptions were found to be secondary to intolerance.

Two study patients exhibited signs of potentially significant gastrointestinal bleeding. The first was a patient admitted to the PICU for severe sepsis, hepatic failure, and coagulopathy who experienced 2 episodes of hematemesis, after which enterai feedings were held. This patient died the following day of multiorgan system dysfunction. The second patient also presented with sepsis, coagulopathy, and multiorgan system dysfunction after bone marrow transplantation. This patient experienced intermittent bloody stools for 4 days before death but had not received enterai feedings for more than 5 days before the bloody stools were noted. The feedings were stopped secondary to vomiting and were never restarted because the patient experienced continued deterioration from the underlying disease process. It is likely that the bleeding noted in these patients was a manifestation of their severe underlying disease process and coagulopathy and not related to enterai feedings. Two other patients experienced 1 episode each of tarry, heme-positive stools. The amount of bleeding was not judged clinically significant in either case, no intervention was necessary, and both patients continued enterai feedings without interruption. None of the patients demonstrated evidence of abdominal organ perforation or necrotizing enterocolitis.

The most common gastrointestinal-related reason for interruption of feedings in this study was vomiting, which occurred in 12 of the 55 patients (22%). Vomiting of enterai feedings and subsequent feeding interruption is of concern because it limits the ability to provide adequate nutrition, may be uncomfortable for the patient, and may lead to increased risk of aspiration of gastric contents. Vomiting is a frequently described side effect of enterai nutrition in the critically ill and is associated with disordered gastric motility.17,18 Various strategies have been used to overcome this problem, including administration of prokinetic agents1,17 and delivery of feedings into the small bowel instead of the stomach.3,13 Neither of these strategies was routinely used in our institution during the study period. Three patients did have nasojejunal feeding tubes, but the specific reason for the placement of these tubes could not be determined. Eight patients in this study did receive prokinetic agents during the study period, yet 3 of the 8 experienced 1 or more episodes of emesis, and another had tube feedings held secondary to a large gastric residual. Although these numbers are too small to draw conclusions, it does not seem that the use of prokinetic agents enhanced feeding tolerance in these patients.

Constipation was encountered frequently in this study, with 20 of the 55 patients (36%) requiring medication for constipation during their PICU course. Although constipation was the most common side effect in our study, it was only responsible for 4 instances of feeding interruption. All of the patients who experienced constipation were receiving narcotics and benzodiazepines at the time they were treated for constipation. It seems likely that these medications were at least partially responsible for the observed constipation. Because medication for anxiolysis and analgesia are frequently required in the intensive care unit, early establishment of treatment regimens to prevent constipation should be considered for patients receiving enterai feedings while receiving these medications.

The retrospective nature, the small number of patients, and the lack of randomization in this study may limit interpretation of the results. The findings, however, suggest that patients requiring cardiovascular medications may tolerate and benefit from enterai nutrition. The study patients’ experience with vomiting, constipation, and other gastrointestinal side effects appears to be consistent with the incidence reported in other studies. This study supports the need for further investigation with randomized, controlled trials to determine whether enterai nutrition can consistently benefit patients receiving cardiovascular medications. In addition, strategies must be designed to counteract common side effects such as vomiting and constipation.

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Wendalyn King, MD, MPH*; Toni Petrillo, MD[dagger]; and Robert Pettignano, MD, MBA, FCCM[double dagger]

From the *Department of Pediatrics, Emory University, Atlanta, Georgia; [dagger]Pediatric Critical Care, Children’s Healthcare of Atlanta at Egleston, Atlanta, Georgia; and [double dagger]Department of Pediatrics, Pediatric Critical Care, Emory University, Atlanta, Georgia

Received for publication March 9, 2004.

Accepted for publication June 7, 2004.

The study was performed at Children’s Healthcare of Atlanta at Egleston, Atlanta, GA.

Correspondence: Wendalyn King, MD, 1645 Tullie Circle, Atlanta, GA 30329. Electronic mail may be sent to wendy_king@oz.ped.emory.edu.

Copyright American Society for Parenteral and Enteral Nutrition Sep/Oct 2004

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