Retrospective Study
Journal of Veterinary Emergency and Critical Care 19(4) 2009, pp 337–346 doi:10.1111/j.1476-4431.2009.00438.x
Nasogastric tube feeding in cats with suspected acute pancreatitis: 55 cases (2001^2006) Jennifer A. Klaus, DVM; Elke Rudloff, DVM, DACVECC and Rebecca Kirby, DVM, DACVIM, DACVECC
Abstract Objective – To evaluate the complications and outcome associated with different nasogastric tube (NGT) feeding techniques in cats with suspected acute pancreatitis. Design – Descriptive retrospective case series Setting – Small animal emergency and referral hospital Animals – The patient database (2001-2006) was searched for cats with suspected acute pancreatitis that received NGT liquid enteral feeding within 72 hours of admission and 12 hours during hospitalization. Measurements and Main Results – Signalment, history, clinical signs, laboratory data and abdominal ultrasonographic examinations were used for suspected diagnosis. Cats were grouped based upon whether they received bolus feeding or continuous rate infusion (CRI) of a liquid diet via the NGT, and whether or not administration of an intravenous amino acid and carbohydrate solution occurred prior to NGT feeding (AAS and non-AAS group, respectively). Fifty-five cats were included. For all cats, NGT feeding was initiated at a mean of 33.5 15.0 hours and the target caloric intake (1.2 X {(30 X BW [kg]) +70}) was reached at 58.0 28.4 hours from presentation. There was a significantly longer time from admission to the initiation of NGT feeding in the 34/55 cats in the AAS group vs. the 21/55 cats in the non-AAS group (P = 0.009). The 8 bolus-fed cats took longer to reach target caloric intake vs. the 47 CRI-fed cats (P = 0.002). Complications associated with NGT feeding for all cats included: mechanical problems (13%), diarrhea (25%), vomiting following NGT placement (20%) and vomiting following NGT feeding (13%). Mean time to discharge for all cats occurred after 78.6 29.5 hours with an overall weight gain of 0.08 0.52 kg. Fifty cats survived 28 days post-discharge. Conclusions – NGT feeding in this group of cats with suspected acute pancreatitis was well tolerated, and associated with a low incidence of diarrhea, vomiting, and mechanical complications. (J Vet Emerg Crit Care 2009; 19(4): 337–346) doi: 10.1111/j.1476-4431.2009.00438.x
Keywords: enteral feeding, enteral nutrition, feline, partial parenteral nutrition, tube feeding
Introduction The prevalence of feline pancreatitis documented in postmortem evaluation of 6504 feline pancreata has been reported by Ha¨nichen and Minkus1 to be acute pancreatitis in 0.26% of cats and chronic pancreatitis in 0.52% of cats. It is difficult to make a diagnosis of acute pancreatitis in the cat without a pancreatic biopsy, therefore a presumptive diagnosis relies on compatible historical, clinical, and ultrasonographic findings.2,3 Clinical signs are often vague and nonspecific, and From the Animal Emergency Center, Glendale, WI 52309, USA. Address correspondence and reprint requests to Dr. Jennifer A. Klaus, Southern Arizona Veterinary Specialty and Emergency Center, 141 E Fort Lowell, Tucson, AZ 85705, USA. Email: dr_jenklaus@yahoo.com & Veterinary Emergency and Critical Care Society 2009
can include lethargy, anorexia, dehydration, vomiting, and weight loss.3–6 Laboratory abnormalities are often variable, and may include neutrophilia, anemia, elevations in alanine aminotransferase, alkaline phosphatase, total bilirubin, and cholesterol, as well as hypocalcemia, hyperglycemia, glucosuria, and ketonuria.3–6 Recently, feline pancreatic lipase immunoreactivity has been promisingly reported as a diagnostic tool.7 Current therapeutic recommendations for treating cats with suspected or confirmed pancreatitis include fasting for at least 2–3 days if vomiting is present.8–10 However, withholding enteral feeding may prove detrimental as the majority of cats with pancreatitis are anorexic at the time of presentation3,5 and concurrent weight loss has been correlated with an increase in 337
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mortality rate.11 In human medicine, early nutritional support is one of the mainstays of therapy.12 Nutritional therapy for feline pancreatitis remains controversial. Some reported nutritional strategies for cats with pancreatitis incorporate partial parenteral nutrition (PPN; 8.5% amino acids, 20% lipids), or total parenteral nutrition (TPN; 6% amino acids, 20% lipids, 50% dextrose), or both instead of enteral feeding.10,11 It has been postulated that enteral feeding will exacerbate pancreatic secretions and inflammation.13,14 Delivering nutrients distal to the duodenojejunal flexure has been described in dogs and humans with acute pancreatitis to bypass cephalic, gastric, and duodenal stimulation of pancreatic enzyme secretion and reduce inflammation.14–17 However, a meta-analysis concluded that early nasogastric (NG) tube nutrition was a breakthrough therapy for human pancreatitis, where no worsening in clinical outcome occurred compared with TPN and nasojejunal tube feeding.18 Anecdotal reports19,20 describe the use of early gastrointestinal feeding, but there are no studies investigating the feeding techniques, complications, and survival rate in cats with suspected acute pancreatitis given enteral nutrition via NG tubes. The purpose of this study is to provide a descriptive retrospective evaluation of feeding techniques, outcome, and incidence of complications in cats with suspected acute pancreatitis given enteral nutrition via NG tubes.
Materials and Methods Criteria for selection of cases The patient database of cats examined at the Animal Emergency Center from July 1, 2001 to December 31, 2006 was searched. Cases selected for review received NG tube feeding of a liquid enteral dieta within 72 hours of presentation and had historical (lethargy, anorexia, vomiting, or diarrhea), clinical (dehydration, hypothermia, or abdominal discomfort), and ultrasonographic findings (an enlarged hypoechogenic pancreas with or without hyperechogenicity of peripancreatic mesenteric fat or a pancreas with mixed hyper- and hypoechogenicity2,6), supportive of acute pancreatitis. All ultrasound examinations were performed by 1 of 2 board-certified veterinary emergency and critical care specialists having 45 years experience performing ultrasound examinations. Medical records had to have detailed history and physical examination findings and an hourly intensive care unit treatment record. The placement of NG tubes in cats is standardized in this hospital and performed by: (1) premeasuring a 5or 8-Fr flexible polyurethane feeding tube from the nose to the last rib; (2) lubricating the tip with lidocaine gel and inserting the tube through 1 nostril to the premea338
sured mark; and (3) suturing the tube to the nose when either gastric contents are aspirated or abdominal radiographs confirm placement in the stomach. To be included in this study, feeding through the NG tube must have been initiated within 72 hours of admission. NG feeding had to have been provided for at least 12 hours and the target caloric intake reached using a liquid enteral diet. Supplemental enteral electrolyte solutionb containing 9% glycine and 69% glucose, and an IV amino acid and carbohydrate solutionc,d (AAS) were the only other means of nutritional supplementation before NG tube feeding acceptable for inclusion. The AAS could have been administered through a peripheral or central venous catheter. The same catheter could also have been used for concurrent IV fluid administration. Data evaluation Signalment, history, presenting clinical signs, ultrasonographic findings, and all types of nutritional support were recorded and evaluated. Data collected pertaining to the administration of NG tube nutrition consisted of: technique of enteral diet administration through NG tube (either bolus or low volume continuous rate infusion [CRI]); time from presentation to initiation of liquid diet feeding; and time from start of NG tube feeding to provision of target caloric requirements. Complications were recorded and included as: tube blockage, tube displacement, hypersalivation, vomiting, and diarrhea. The use and type of adjunctive therapy (promotility agents and antiemetics, insulin, antibiotics, or analgesic agents) was recorded. Patient parameters identified included weight change, whether or not there was return of appetite, and length of hospitalization. Outcome was recorded with survivors alive at least 28 days after hospital discharge. Cats that received IV AAS solution before and during NG tube enteral feeding were designated as the AAS group. This group was compared with the non-AAS group for any significant effect on time to target caloric intake, complications, and outcome. The two different techniques for the administration of enteral diet through the NG tube, bolus and CRI infusion were also evaluated for their impact on time to target caloric intake, complications, and outcome. Statistical analysis Descriptive data were examined graphically and are presented as mean SD for normally distributed data, and as median (range) for skewed data. To assess the effects of providing AAS and bolus or CRI methods on various feeding time points and major outcomes in the study, continuous outcomes were examined using a 2-way ANOVA; this tested whether there was a significant
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difference between bolus and CRI, and between AAS and non-AAS for the outcomes of interest. For binary outcomes, logistic regression analysis was used. Odds ratios were calculated and tested for significance. Odds ratios of 0 occurred when there were no events in a combination of the outcome and covariate (eg, there were no cats that had diarrhea after bolus feeding). Fisher’s exact test was used to measure association in those cases. In all analyses commercially available softwaree was used and Po0.05 was considered significant.
Results Study population From July 1, 2001 to December 31, 2006, 18,902 cats were examined at the Animal Emergency Center. Seventy of these cases were identified for possible inclusion into the study, representing 0.37% of all cats seen. Fifteen of these cases were excluded from the study. Eight of the 15 records were incomplete. Another 6 cats failed to reach target NG tube feedings in hospital. Of these 6 cats, 2 were euthanized during surgery before reaching maintenance caloric feeding, and 4 cats were sent home or transferred to another veterinarian before 12 hours of inhospital NG tube feeding. One case was excluded because the cat had received esophagostomy tube feedings before reaching maintenance NG tube feeding. Fifty-five cats met the inclusion criteria for the study. Forty-six were domestic short hair cats, 5 were domestic long hair cats, 2 were domestic medium hair cats and there was 1 Birman, and 1 Himalayan cat. The average age of the cats was 8.4 years (1–18 y) and 29 of 55 (53%) were male. Clinical signs and ultrasound findings A history of lethargy was reported in all cases, decreased appetite in 53 of 55 cats (96%), and complete anorexia ranging from 1 to 8 days in 38 of 55 (69%) cats. Dehydration was present in 53 of 55 (96%), weight loss in 11 of 55 (20%) and diarrhea in 9 of 55 (16%) cats. Forty-two of 55 (76%) cats had a history of vomiting, and 29 of these cats received AAS (29/34; 85%), which was not significant (P 5 0.07). Ultrasonographic examination of the abdomen documented a hypoechoic pancreas with a hyperechoic mesentery in 29 of 55 (53%) cats, a mixed hypoechoic/ hyperechoic pancreas in 14 of 55 (25%), and a hypoechoic pancreas without mesenteric changes in 12 of 55 (22%) cats. Concurrent diseases In addition to acute pancreatitis, the following abnormalities were documented in the history, clinical findings,
or through diagnostic testing or ultrasonographic examination of this population of cats: hepatic changes (33/55 [60%]), renal insufficiency (19/55 [35%]), thickened intestines (11/55 [20%]), diabetes mellitus (7/55 [13%]), and upper respiratory disease (4/55 [7%]). Inflammatory bowel disease was diagnosed in 3 of 9 cats based on histopathologic findings in a surgical biopsy (1 cat) or a positive response to a hypoallergenic diet (2 cats).
Nutritional support After NG tube placement, gastric suctioning was performed every 4–6 hours in all cases for the duration of NG tube placement. Supplemental electrolyte solutionb was administered to all patients through the NG tube before liquid enteral diet feeding by either CRI (0.55– 2.2 mL/kg beginning 14.5 14.3 hours after admission) for 47 of 55 (85%) cats or bolus infusion (2.2–4.4 mL/kg every 4 hours beginning at 20.3 13.1 hours after admission) for 8 of 55 (15%) cats. There was no statistical difference in enteral electrolyte solution volume or onset of administration between the AAS and non-AAS groups (see Table 1, P 5 0.17) or between bolus and CRI groups (see Table 2, P 5 0.19). An 8.5% amino acid solution with 5% dextrosec was administered to 14 cats and a 3% amino acid and 3.5% glycerol solutiond to 20 cats IV. At the administered rate of 1.1 mL/kg/h, the first solution provided 14.4 kcal/kg/ d (2.3 g of protein/kg/d and 1.3 g of dextrose/kg/d), and the second solution administered at 2.2 mL/kg/h provided 13.2 kcal/kg/d (1.6 g of protein/kg/d and 1.6 g of carbohydrate/kg/d). The average time from admission to start of AAS was 13.7 20.8 hours. NG tube feedings with a liquid enteral diet were initiated when there was low volume (o1 mL/kg/h of NG tube suction volumes) of gastric fluid residuals and as long as no vomiting had occurred for at least 12 hours. NG tube feedings with the liquid enteral diet were started at 25–50% of the target caloric intake (0.55–1.1 kcal/kg/h CRI, or 2.2–4.4 kcal/kg bolus every 4 hours). Over 12– 72 hours, feedings were gradually increased in volume to reach the target caloric intake of 1.2 resting energy requirement (RER) (2.2 kcal/kg/h CRI or 8.8 kcal/kg bolus every 4 hours). The target caloric intake provided 30% of caloric density as protein, 45% of caloric density as lipids, and 25% of caloric density as carbohydrates. Infusion rates were incrementally increased based on patient response and residual gastric volumes. When it was determined that trickle feeding was tolerated at target caloric intake, a transition to bolus feeding would occur in preparation for hospital discharge. The NG tube was left in place when the cat was not voluntarily consuming adequate oral nutrition or the pet owner declined esophagostomy tube placement.
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55 34 21
All AAS Non-AAS P value OR 95% CI
2.2, 13.3
3.19,19.3
33.5 15.0 37.4 15.1 27.1 13.5 0.009nn
15.4 14.2 17 15.7 12.6 10.9 0.17 0.6, 29.4
58.0 28.4 61.8 30.7 52.1 23.7 0.07
Admission to TIn (h; mean SD)
12, 17.3
16.0 (0–165) 15.5 (0–165) 16 (0–104) 0.76
Start NGT feeding to TIn (h; median (range))
1.6, 29.5
78.6 29.6 84.5 31.1 68.3 17.2 0.09
Length of hospital stay (h; mean SD)w
0.4, 0.05
10.08 0.52 0.02 0.43 10.24 0.51 0.12
Weight gain (kg; mean SD) 38/50 (76%) 26/31 (84%) 12/19 (63%) 0.16 2.57 0.68, 9.69
Discharged with NGTw
55 8 47
All Bolus CRI P value OR 95% CI
33.5 15.0 36.0 18.5 33.0 14.8 0.28 4.9, 17.2
15.4 14.2 20.3 13.1 14.5 14.3 0.19
3, 18.0
11.6, 57.3
58.0 28.4 84.5 58.8 54.5 20.5 0.005nn
Admission to TIn (h; mean SD)
14.3, 60.0
16.0 (0–165) 34 (14–165) 15 (0–104) 0.002nn
Start NGT feeding to TIn (h; median (range))
n
TI, target NGT caloric intake is 52.8 kcal/kg/d. wThe 5 euthanized cats are not included. nn Po0.05. NGT, nasogastric tube; CRI, continuous rate infusion; OR, odds ratio; CI, confidence interval.
n
Group
Admission to NGT feeding (h; mean SD)
Admission to NGT electrolyte solution (h; mean SD)
38, 4.01
78.6 29.6 60.7 17.2 81.5 28.1 0.12
Length of hospital stay (h; mean SD)w
0.3, 0.37
10.08 0.52 10.16 0.23 10.09 0.51 0.97
Weight gain (kg; mean SD)
38/50 (76%) 6/8 (75%) 32/42 (76%) 0.71 1.41 0.22, 8.71
Discharged with NGTw
Table 2: NGT feeding time intervals, length of hospitalization, weight change, discharge with NGT, and survival for CRI versus bolus feeding
n
TI, target NGT caloric intake is 52.8 kcal/kg/d. wThe 5 euthanized cats are not included. nn Po0.05. NGT, nasogastric tube; AAS, amino acid solution; OR, odds ratio; CI, confidence interval.
n
Group
Admission to NGT feeding (h; mean SD)
Admission to NGT electrolyte solution (h; mean SD)
50 (91%) 8 (100%) 42 (89%) N/A N/A N/A
Survived to day 28 after discharge
50 (91%) 31 (91%) 19 (90%) 0.49 0.48 0.06, 3.79
Survived to day 28 after discharge
Table 1: NGT feeding time intervals, length of hospitalization, weight change, discharge with NGT, and survival in AAS-fed versus non–AAS-fed patients
5 (9%) 0 5 (11%) N/A N/A N/A
Euthanized
5 (9.1%) 3 (9%) 2 (10%) 0.49 0.48 0.06, 3.79
Euthanized
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& Veterinary Emergency and Critical Care Society 2009, doi: 10.1111/j.1476-4431.2009.00438.x
NG tube feeding in cats with suspected acute pancreatitis
Table 3: Complications associated with NGT placement in cats with pancreatitis receiving or not receiving AAS
Group
n
All AAS Non-AAS P value OR 95% CI
55 34 21
Vomiting admission until NGT feeding
Vomiting after NGT feeding (in hospital)
Diarrhea following NGT feeding
Hypersalivation with NGT placement
Hypersalivation with NGT feeding
Tube dislodgement
Tube obstruction
11 (20%) 8 (24%) 3 (14%) 0.18 3.38 0.5, 19.7
7 (13%) 6 (18%) 1 (5%) 0.26 3.60 0.39, 32
14 (25%) 12 (35%) 2 (10%) 0.08 4.42 0.85, 22
3 (5%) 2 (6%) 1 (5%)
2 (4%) 1 (3%) 1 (5%)
6 (11%) 6 (18%) 0
1 (2%) 0 1 (5%)
NGT, nasogastric tube; AAS, amino acid solution; OR, odds ratio; CI, confidence interval.
There was a significantly longer time from admission to initiation of NG tube feeding found in the AAS group compared with the non-AAS group, 37.4 15.1 versus 27.1 13.5 hours, respectively (P 5 0.009). The time from initiation of NG tube feeding to target caloric intake of NG feeding for the AAS group was 15.5 hours and was 16 hours in the non-AAS group, which was not significantly different (P 5 0.76). These same data were evaluated for CRI and bolus enteral feeding techniques (see Table 2). The time from the start of NG tube feedings to target caloric intake took 15 hours in the CRI-fed group compared with 34 hours in the bolus-fed group, which was significant (P 5 0.002). There was no significant difference between bolus-fed and CRI-fed groups for the time from admission to initiation of NG tube feeding (P 5 0.28). Cats being CRI fed were converted to bolus feedings at a mean of 32.4 19.1 hours after initiation of feeding. Outcome Length of hospital stay, weight change, and survival data are shown for AAS and non-AAS groups in Table 1 and for bolus and CRI-fed groups in Table 2. No statistical significance was detected between groups for these parameters. Of the cats that survived, 22 of 50 (44%) cats started eating voluntarily in the hospital, and 38 of 50 (76%) cats were discharged from hospital with the NG tube in place to allow the owner to continue bolus feeding. The NG tube was replaced with esophagostomy tube feedings in 2 of 50 (4%) cats. Six of 50 (12%) cats were voluntarily eating adequately, not requiring supplemental feeding. Four of 50 (8%) were syringe fed at home without NG tube supplementation. Five cats were euthanized, 4 due to the severe decline in their clinical condition and 1 due to the owner’s inability to perform home care, all having been CRI fed. There was no statistical significance between the administration of AAS and the population of cats that were euthanized (P 5 0.49). No cats died.
Complications The frequency of vomiting before and after NG tube feeding, and the incidence of diarrhea and hypersalivation after NG tube placement were not significantly different between the AAS and non-AAS groups (see Table 3). Bolus-fed cats had significantly more vomiting episodes after NG tube placement and before the initiation of feeding than did the CRI-fed cats (see Table 4, P 5 0.02). However, none of the bolus-fed patients vomited after feeding began. No other variable was significantly associated with vomiting. Four of the 16 cats (25%) that vomited in hospital had vomiting reported after discharge from the hospital, and 1 of these patients was euthanized. An additional 5 cats that had not vomited at all in the hospital vomited at home after discharge. Fourteen cats, all in the CRI group, had diarrhea after NG tube feeding, and no statistical significance was found between the AAS and non-AAS groups (P 5 0.08). One or more mechanical complications with the NG tube were found in 7 of 55 (13%) cats, with tube dislodgement occurring in 6 cats and tube obstruction in 1 cat (see Table 4). One of the cats removed the NG tube following hospital discharge and required endoscopy to remove a segment of the NG tube from the stomach. A nasoesophageal tube was subsequently placed in that cat for continued feeding. One cat had an obstruction of the NG tube that cleared without requiring tube replacement. Three cats were hypersalivating following NG tube placement (1 in the bolus-fed group) and following initiation of NG tube feeding, 2 cats were hypersalivating in the CRI-fed group. Adjunctive therapy Treatment other than IV fluid replacement included administration of promotility and antiemetic agents, analgesic drugs (single agent opioid or combination opioid and other analgesics), insulin, and antibiotics. Promotility agents were used in 48 of 55 (87%) cats (see Tables 5 and 6). There was no significant difference
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Table 4: Complications associated with NGT placement in cats with pancreatitis that were fed by bolus infusion compared with CRI
Group
n
All Bolus CRI P value OR 95%CI
55 8 47
Vomiting admission until NGT feeding
Vomiting after NGT feeding (in hospital)
Diarrhea following NGT feeding
Hypersalivation with NGT placement
Hypersalivation with NGT feeding
Tube dislodgement
Tube obstruction
11 (20%) 4 (50%) 7 (15%) 0.02n 9.09 1.41, 58.4
7 (13%) 0 7 (15%) N/A N/A N/A
14 (25%) 0 14 (30%) N/A N/A N/A
3 (5%) 1 (13%) 2 (4%)
2 (4%) 0 2 (4%)
6 (11%) 1 (13%) 5 (11%)
1 (2%) 1 (13%) 0
n Po0.05. NGT, nasogastric tube; CRI, continuous rate infusion; OR, odds ratio; CI, confidence interval.
between promotility agent usage in the AAS group and non-AAS group (P = 0.15), or in the CRI group and bolus-fed group (P = 0.88). Analgesics were used in 35 of 55 (64%) cats, and antibiotics in 51 of 55 (93%) cats. Six of 7 cats presenting with a history of diabetes mellitus were treated with CRI or subcutaneous insulin administration. Insulin therapy was not used in any nondiabetic hyperglycemic cats.
Discussion The retrospective data from these 55 cats with suspected acute pancreatitis demonstrate that enteral feeding of a liquid diet, by CRI or bolus methods of administration, was associated with few clinically significant complications and no deleterious effects on morbidity and mortality. Feeding could occur early in the course of the hospitalization and a survival rate of 91% was documented in this population of cats. This is the first retrospective review evaluating the feeding techniques, complications and outcome of enteral feeding by NG tube as a treatment strategy for suspected acute pancreatitis in cats. The prevalence of 0.37% suspected acute feline pancreatitis in all cats
examined is similar to the 0.26% prevalence of feline acute pancreatitis reported elsewhere.1 It is likely, however, that our referral hospital’s true prevalence is higher because abdominal ultrasonography, although highly specific, has been reported to be 20–35% sensitive for the diagnosis of acute pancreatitis.21,22 The cats were divided into groups according to feeding technique in order to evaluate any potential impact on complications and outcome. Clinician preference, anticipation of delayed enteral feeding, time to target caloric intake, and financial limitations may have played a role in the decision of whether or not to initiate nutritional support with AAS solution. In addition, bolus feedings may be elected when financial limitations restrict days in hospital. In this population of cats with suspected acute pancreatitis, the proportion of males (53%) to females (47%), domestic short hair breed predilection, and age of cats is comparable with previously reported studies of cats with acute pancreatitis.3–6 There were a large number of anorexic cats (69%), and 96% of cats had a decreased appetite on presentation. This is similar to another retrospective study with 40 cats with pancreatitis, where 84% were completely anorexic and 97%
Table 5: Promotility and antiemetic therapy in cats with pancreatitis that received nasogastric tube feedings in addition to or without AAS
Group
n
All AAS Non-AAS P value OR
55 34 21
Promotility agents used 48 (87%) 31 (91%) 17 (81%) 0.15 3.87
Single agent promotility: Cisapride
Single agent promotility: Metoclopramide
Single agent antiemeticn
Combination promotility agents antiemeticsw
23 (42%) 16 (47%) 7 (33%)
8 (15%) 4 (12%) 4 (19%)
1 (2%) 1 (3%) 0
17 (31%) 11 (32%) 6 (29%)
Single antiemetic agent chlorpromazine. Chlorpromazine or ondansetron as a combination agent in 3/55 and 1/55 cases, respectively. AAS, amino acid solution; OR, odds ratio. n
w
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Table 6: Promotility and antiemetic therapy in cats with pancreatitis that received nasogastric tube feedings by CRI or bolus infusion
Group
n
All Bolus CRI P value OR
55 8 47
Promotility agents used 48 (87%) 7 (88%) 41 (87%) 0.88 1.20
Single agent promotility: cisapride
Single agent promotility: metoclopramide
Single agent antiemeticn
Combination promotility agents antiemeticsw
23 (42%) 1 (13%) 22 (47%)
8 (15%) 4 (50%) 4 (9%)
1 (2%) 0 1 (2%)
17 (31%) 2 (25%) 15 (32%)
Single antiemetic agent chlorpromazine. Chlorpromazine or ondansetron as a combination agent in 3/55 and 1/55 cases, respectively. AAS, amino acid solution; OR, odds ratio. n
w
had a reduced appetite.3 In that study, only 35% of cats with severe pancreatitis were vomiting at presentation, compared with 76% in this retrospective review. Inflammatory bowel disease, diabetes mellitus, enteritis, cholangiohepatitis, chronic interstitial nephritis, acute tubular necrosis, and pyelonephritis are estimated to occur in 92% of cats with acute pancreatitis.5,9,23,24 Concurrent diseases have been reported to be associated with a worse outcome in cats with acute pancreatitis.3,4,9 Forty-six of 55 (84%) cats in this study had suspected concurrent diseases. Diabetes mellitus is reported to occur in 3–15% of cats with pancreatitis5 and was present in 7 of 55 (13%) of cats in this study. Hepatopathy and renal insufficiency were noted in 33 of 55 (60%) and 19 of 55 (35%) cats, respectively, in this study. Hepatic lipidosis can occur within 72 hours of fasting, and has been reported as an exacerbating illness in 59% of cats with pancreatitis,3,24,25 increasing mortality up to 80%.4 Recommendations for nutritional support have included using PPN with AAS and lipids of various compositions or TPN if severe vomiting or ileus is present.26 Enteral nutrition is safer and less expensive than TPN but effect on outcome in human clinical studies is still debated.12 One human clinical trial found that treating severe acute pancreatitis patients with total enteral feeding significantly reduced infectious complications, multiorgan failure, and mortality compared with TPN.27 However, enteral nutrition in human acute pancreatitis patients did not result in significant decreases in mortality and morbidity compared with TPN as reported by 2 meta-analyses.28,29 Not surprisingly, nutritional therapy for feline pancreatitis also remains controversial, and in a study by Hill and Van Winkle3 of 40 cats with the diagnosis of acute pancreatitis, rapid deterioration and death occurred in 3 that were force fed while the other cats were permitted to regain appetite on their own. The use of NG tubes in this study permitted introduction of enteral feeding in the anorexic cat without the restraint and stress associated with forced oral feeding.
NG tube placement is rapid and nonsurgical, with no need for fluoroscopic guidance, providing some benefits over jejunal and nasojejunal feeding methods. Current published guidelines for treating suspected acute feline pancreatitis recommend cautious introduction to food if the patient is anorexic, and withholding enteral feeding for 2–3 days if the patient is vomiting.8–10 These guidelines suggest that slow introduction to feeding should be attempted with a low-fat, carbohydraterich diet. Jejunostomy, nasojejunal, NG, esophagostomy, or gastrostomy tubes have been given as options for methods of feeding8,11,19,30,31 and specific recommendations have been made to reach maintenance caloric requirements over 3–4 days when jejunal tube feeding is used in cats with pancreatitis.32 Withholding enteral nutrition in the sick cat could contribute to morbidity. Cats have a high dietary protein requirement, 2–3 times that of dogs, making them susceptible to protein-energy malnutrition and severe lean muscle loss when fasting.33–35 Negative nitrogen balance can result in gastrointestinal ileus, villous atrophy with poor absorptive capabilities, and increased risk of bacterial translocation.19 Deleterious effects on the renal, pulmonary, immune, cardiovascular, and musculoskeletal systems have been reported as a consequence of negative nitrogen balance,19 and withholding enteral nutrition could exacerbate concurrent illness in cats with pancreatitis. In addition, decreased arginine and methionine may limit the synthesis of liver proteins and phospholipids, contributing to the development of hepatic lipidosis.35 Currently, NG tube feeding in humans with pancreatitis is being reevaluated. In 26 humans with severe acute pancreatitis, NG tube feeding was well tolerated in 22 patients, with gastric stasis occurring in 3 patients; all patients survived.36 Other human studies have shown no increase in patient perception of pain, acute phase response, requirement of analgesics, length of hospital stay, or mortality with NG tube feeding when compared with NJ feeding.37,38 In addition, NG tubes
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were easier and less costly to place and maintain than surgically placed jejunal or fluoroscopically placed nasojejunal tubes.37,38 The AAS is administered to augment calories in patients not meeting their daily caloric needs through enteral feeding. The AAS can provide close to 30% daily caloric needs in the cat. In addition, these solutions contain balanced electrolytes, arginine, and branched-chain amino acids (leucine, isoleucine, and valine). IV arginine supplementation has been shown to enhance both cellular and humoral immunity,39 and parenteral branched-chain amino acids preserve intestinal morphology and protein content.40 The 13.7 20.8 hours from presentation to the onset of AAS administration was earlier in this study than reported by Chan et al,41 where an 8.5% amino acid and 20% lipid solution was started at a mean of 43.2 hours after hospitalization. Similarly, in a large retrospective study evaluating TPN, 35 of 75 (47%) of cats had a diagnosis of pancreatitis, and a median of 36 hours elapsed before TPN was initiated.11 The ultimate goal of NG tube enteral feeding is to reach the necessary volumes to provide target caloric intake as rapidly as possible without causing deleterious effects such as nausea, vomiting, or diarrhea. In this study, target caloric intake with enteral feeding was reached at a mean of 58.0 28.4 hours from admission for all cats. This is more rapid than recommendations made for jejunal feeding to reach maintenance caloric needs over 3–4 days.32 Also, the bolus-fed group took a significantly longer time to reach target caloric intake than the CRI-fed group (P 5 0.002). When the enteral diet can be delivered as a CRI, the volume and concentration can be more carefully titrated. The target nutrition used represented 1.2 RER for a standard 5.5 kg cat. RER can be multiplied by an illness factor (1–1.25 in cats) to calculate the metabolic energy requirement.19,42 This calculation is being used because it was the caloric intake commonly recommended during that treatment period. The recommendations have since changed to strictly feed cats with pancreatitis the RER without adding an illness factor.43 Sixteen of 55 (29%) cats vomited while in the hospital. The incidence of vomiting with enteral feeding throughout the groups may have been reduced by a combination of factors: periodic gastric aspiration of air and fluid by NG tube, testing tolerance of NG tube feeding with an electrolyte solution before giving the enteral diet, the addition of antiemetics, or promotility agents, or both, and the selection of a specific feeding technique for each individual cat. Factors that may have contributed to increased vomiting incidence include the adverse effects of adjunctive therapies used, such as antibiotics and opioid analgesic agents. It cannot be 344
determined from the individual patient records what criteria were used to determine the need for analgesic or antibiotic agents. Only 7 of 55 (13%) cats vomited after feeding, and each had a history of vomiting before initiation of feeding. This might have been coincidental, or a factor related to their ongoing disease processes. In these cases, enteral nutrition was discontinued temporarily additional antiemetics or promotility agents provided, and NG tube feeding was reinstated at a slower pace. Bolus-fed cats in this study had a statistically significant greater incidence of vomiting from time of NG tube placement until start of feeding the enteral diet. The explanation for this is not clear, but vomiting may have occurred in association with the bolus administration of the electrolyte solution after NG tube placement compared with delivering the solution by a CRI. No other variable was associated with vomiting. The frequency of vomiting after initiation of NG tube feeding with the enteral diet occurred with the same frequency in AAS- or non–AAS-fed cats (P 5 0.26), while none of the cats in the bolus group vomited. Mechanical complications associated with NG tube feeding occurred in 7 of 55 (13%) of the cats in this study, with manual removal of the NG tube occurring in 6 cats and tube obstruction in 1 cat. This is similar to a study by Abood and Buffington,44 where 2 of 26 (8%) of critically ill cats removed their NG tube. No NG tube obstructions occurred in the Abood study or a similar study by Crowe et al.45 Also, 5 of 55 (9%) of cats in our study were hypersalivating following NG tube placement or feeding. The hypersalivation could be attributed to the tube placement, pain, or nausea associated with the suspected acute pancreatic disease. The incidence of hypersalivation was not reported in other studies reporting on suspected pancreatitis or NG tube feedings. Previous studies implicated enteral feeding with a liquid diet as the cause of diarrhea in 11.5–37.5% of canine and feline patients.30,44,45 Humans experience a 14.5% occurrence of diarrhea with liquid enteral diet feeding.46 Fourteen of 55 (25%) cats in this study developed diarrhea that had not previously been documented before feeding. The antibiotics that were administered may have contributed to the diarrhea. The administration of AAS was not associated with the development of diarrhea (P 5 0.08) and none of the bolus-fed cats developed diarrhea. Length of hospitalization, weight gain, and outcome were not significantly different between AAS and nonAAS groups or between CRI-fed and bolus-fed groups. During the treatment period, the cats experienced a mean weight gain of 0.08 0.52 kg, or 1.5%, which is in
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NG tube feeding in cats with suspected acute pancreatitis
contrast to another study, in which cats fed a liquid polymeric diet over 7 days experienced an average weight loss of 3.8%.45 It is likely that the weight gain was a combination of correction of dehydration through fluid administration and from providing nutritional support. No records reported signs of fluid overload or intolerance in any of the 55 cats. Mean hospitalization time was 78.6 29.6 hours. This length of hospitalization is relatively short in comparison with a gastrojenuostomy and a jejunostomy tube study where patients with pancreatitis or other diseases were hospitalized for 168–504 hours for therapy.30,32 It is unknown, however, if the cats in these past studies were voluntarily eating their caloric requirement at discharge. In addition, comparison of the severity of disease with this study is not possible. The mortality rate of cats with suspected pancreatitis fed by jejunostomy tubes, PPN and TPN has previously been reported. Swann et al30 reported that of 8 cats fed by jejunostomy tube (6 of 8 having pancreatitis), 4 of the 8 cats (50%) were euthanized. The study did not clarify whether 2, 3, or all of the euthanized cats had pancreatitis. Chan et al41 evaluated the use of PPN in cats with pancreatitis among other diseases, and reported that 19% died or were euthanized. In that study, more cats survived when PPN was augmented with enteral nutrition. A retrospective study by Pyle et al11 found a 46% mortality rate in 35 cats with pancreatitis fed by TPN. In the few small studies using NG tubes in human pancreatitis, all patients survived.36,37 Larger human studies using various feeding methods report a 85– 99.3% survival rate in patients with acute pancreatitis.47,48 This retrospective study of 55 cats with suspected acute pancreatitis that were enterally fed with an NG tube-delivered liquid diet showed a 91% survival (50/55). All cats that were euthanized had been fed their liquid enteral diet by CRI. This feeding technique had most likely been chosen for these cats to allow a gradual adjustment in volume and concentration of liquid diet in this critical population. Because this was a retrospective study, the patient populations were not randomized into standardized feeding groups making it more difficult to evaluate results from each subgroup without bias. In addition, as the method of diagnosis and severity of illness is variable, it is not possible to accurately compare this study with previously reported studies looking at nutrition and feline pancreatitis. Combining the feline pancreatic lipase immunoreactivity test with the ultrasonographic findings would have increased the sensitivity for a stronger antemortem diagnosis of acute pancreatitis,7 and should be considered as part of any future studies looking into the benefits of NG tube feedings in cats with pancreatitis.
Conclusion Early NG tube feeding (o72 hours after admission) of a liquid enteral diet by bolus or CRI feeding was tolerated well and resulted in few clinically significant complications. Enteral nutrition by NG tube should be considered as a means of nutritional management for suspected acute feline pancreatitis.
Footnotes a
b c
d e
CliniCare Feline liquid diet, Abbott Laboratories, Animal Health, North Chicago, IL. Resorb, Pfizer Animal Health, Exton, PA. FreAmine III 8.5%, McGaw, Irvine, CA and 5% dextrose, Baxter Healthcare, Deerfield, IL. ProcalAmine, B. Braun Medical Inc., Irvine, CA. SAS 9.1, SAS Institute Inc., Cary, NC.
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