Introduction
Gastrointestinal foreign body obstructions (GIFBOs) are among the most common veterinary emergencies that require surgical intervention. Clinical signs come as result of the local and systemic abnormalities from the gastrointestinal obstruction.1 The obstruction results in decreased intestinal motor activity, electrolyte disturbances, acid-base abnormalities, and, in severe cases, systemic illness such as bacterial sepsis and multiple organ dysfunction syndrome.2ā4 Depending on the location, duration, and severity of the gastrointestinal obstruction, a dogās presentation and clinical signs may vary.1 Common clinical signs and physical examination findings include vomiting, anorexia, lethargy, diarrhea, dehydration, abdominal pain, and palpation of an abdominal mass lesion.1
Dogs that present with GIFBs are ideally hemodynamically stabilized with aggressive fluid therapy prior to anesthesia and surgical management.5ā8 Luminal distention and increases in pressure secondary to GIFBO can lead to alterations in blood supply resulting in compromise of the gastrointestinal tract, leading to more complex procedures.9 Decreased gastrointestinal perfusion due to mechanical obstruction may also lead to intestinal ileus, intestinal wall edema, bowel ischemia, and eventual septic peritonitis due to bowel perforation.10ā12 Oxygen demand in the intestine may not be adequately met during cases of GIFBO due to decreased perfusion from intraluminal distention and subsequent increased pressures as well as decreased stroke volume from dehydration.7 Prior to surgery, it is then recommended that a dog is hemodynamically stabilized and electrolyte derangements are corrected with aggressive fluid management.6 Although it has been shown that the final outcome of GIFBO surgery may not be affected by immediate versus delayed surgery,13 the length of fluid resuscitation on anesthetic stability of dogs with GIFBO has not been specifically investigated to our knowledge.
The first objective of the study was to compare the impact of preoperative fluid resuscitation on anesthetic cardiovascular parameters and interventions. The second objective was to evaluate the impact of preoperative fluid resuscitation on the integrity of intestinal tissue during surgery and postoperative complications. The hypotheses of this study were that, in dogs undergoing surgical intervention for GIFBO, (1) those receiving more preoperative fluids and longer preoperative fluid resuscitation would require less anesthetic intervention, and (2) this would not impact intestinal wall integrity or postoperative complications.
Methods
Medical records and surgery logs were searched for all dogs that underwent GIFB removal between May 2017 and August 2022 at our institution. Exclusion criteria for the study were dogs with incomplete preoperative medical records, absent time-stamped fluid purchases, incomplete anesthesia and surgery reports, and dogs without at least a 7-day follow-up.
Medical records review
Medical records were reviewed for signalment, presentation time, initiation of fluid resuscitation, duration of clinical signs prior to presentation, initial examination findings (temperature, heart rate, respiratory rate, mentation, hydration status), preoperative bloodwork (PCV, total protein, BUN, creatinine, lactate, blood glucose, estimated platelet count, albumin, sodium, potassium, chloride, pH), as well as anesthesia and surgery data. For hydration status, dogs were categorized as ādehydratedā if dehydration was described within the medical record. The estimated level of dehydration (percentage) was recorded when available in the record. Information collected regarding preoperative fluid management included the use of crystalloid product, total crystalloid bolus volume, total crystalloid bolus dose, crystalloid rate, use of synthetic colloid product, total synthetic colloid bolus volume, total synthetic colloid bolus dose, and synthetic colloid rate. Surgical data, anesthetic parameters, and postoperative outcomes were also reviewed. The duration between admission and fluid treatment, fluid treatment and anesthesia, fluid treatment and surgery, and admission to discharge time were calculated on the basis of the time points listed previously.
The anesthetic protocol used for each dog was based on clinician preference. Anesthetic information collected included premedications and the induction medications used, initial heart rate in beats per minute (bpm; normal, 60 to 160 bpm), noninvasive systolic blood pressure values (normal, 90 to 160 mm Hg), noninvasive mean arterial blood pressure values (normal, 60 to 100 mm Hg), noninvasive diastolic blood pressure values (normal, 60 to 90 mm Hg), fluid bolus administration (mL/kg), fluid rates (mL/kg/d), and the use of synthetic colloids, anesthetic drug administration, and blood product use. Anesthetic drug administration only included the use of dopamine, dobutamine, atropine, or norepinephrine. Administration of blood products and anesthetic drugs were collected from the anesthesia record. The following surgery-specific information was recorded from the medical record and surgery report: foreign body type and location, presence of perforation, procedures performed, and the clinician performing the surgery (diplomate or resident of the American College of Veterinary Surgeons). The ICU treatment sheets were reviewed for signs of perioperative complications including vomiting, diarrhea, and regurgitation as well as whether the dog ate a meal within 24 hours of anesthetic recovery. The records were also reviewed for survival to discharge, follow-up of at least 7 days after discharge by phone in the communication records or in person at a veterinary hospital (eg, suture removal or incision recheck) after discharge, and the occurrence of any complications related to the procedures performed. Complications were defined as catastrophic (directly related to death or cause for euthanasia), major (requiring additional medical or surgical treatment to resolve), or minor (no additional treatment required to resolve) according to previous guidelines.14
Fluid resuscitation groups
Selected continuous numerical variables were converted to categorical variables of 3 groups each. Fluid resuscitation length (time between the initiation of fluid resuscitation and anesthetic induction) was divided into < 2, 2 to 6, and > 6 hours; total amount of fluid bolus received was divided into < 20, 20, and > 20 mL/kg; and preoperative fluid rate was divided into < 120, 120, and > 120 mL/kg/d.
Statistical analysis
Statistical analysis was performed with a commercially available software program (STATA, version 18.9; StataCorp). Normality of continuous data was assessed by visual inspection of the histogram and normal quantile plot. Continuous data that are normally distributed are presented as mean Ā± SD. Categorical variables are reported as a fraction (percentage). Missing observations were handled with listwise deletion prior to statistical analysis. The association between fluid resuscitation groups and 17 independent variables was assessed in 3 separate ordered logistic regression models, with ORs and 95% CIs reported. The assumption of proportional odds was assessed by a likelihood-ratio test of proportionality of odds across response categories. P values < .05 in the regression models were considered significant.
Results
After the medical record database was reviewed, 337 dogs matched the search criteria to be involved in the study. Forty dogs had to be excluded from the study due to incomplete anesthesia records (n = 9) or the absence of a fluid purchase timestamp prior to surgery (31). The remaining 297 dogs were included and consisted of 145 (48.8%) castrated males, 53 (17.8%) intact males, 71 (23.9%) spayed females, and 28 (9.4%) intact females. Sixty-six dog breeds were represented within the population, with 73 (24.6%) mixed-breed dogs, 32 (10.8%) Labrador Retrievers, and 21 (7.1%) Golden Retrievers being the most represented breeds. The mean age and body weight at presentation were 48.5 Ā± 41.9 months and 25.2 Ā± 13.9 kg, respectively.
The mean duration of clinical signs prior to initial presentation was 57.6 Ā± 74.4 hours. Reported clinical signs at the time of presentation included vomiting for 274 (92.3%) dogs, inappetence for 156 (52.5%) dogs, lethargy for 131 (44.1%) dogs, diarrhea for 47 (15.8%) dogs, regurgitation for 22 (7.4%) dogs, and pain for 19 (6.4%) dogs. The mean temperature, heart rate, and respiratory rate reported at the time of presentation were 38.8 Ā± 0.7 Ā°C (101.9 Ā± 1.2 Ā°F), 128.9 Ā± 28.1 bpm, and 32.1 Ā± 9.6 respirations/min, respectively. Abnormal mentation was reported in 31 (10.4%) dogs, and dehydration was reported in 127 (42.8%) dogs. Percent dehydration was reported in 101 of the 127 dogs (79.5%) reported to be dehydrated. Of the dogs that had percent dehydration reported, 57 (56.4%) were 5% dehydrated, 33 (32.7%) were 6% to 7% dehydrated, and 11 (10.9%) were > 7% dehydrated. Specific preoperative bloodwork parameters are reported in Table 1. Platelet estimates were reported in 213 (71.7%) dogs, with a decreased, adequate, and increased platelet count noted in 11 (3.8%), 257 (89.5%), and 19 (6.6%) dogs, respectively.
Preoperative lactate, PCV, total solids, BUN, creatinine, blood glucose, platelet estimate, albumin, sodium, potassium, chloride, and pH results for 297 dogs with gastrointestinal foreign body obstruction.
| Preoperative bloodwork | No (%) of reported values | Mean Ā± SD | Reference range |
|---|---|---|---|
| Lactate (mmol/L) | 45 (15.2) | 2.1 Ā± 1.1 | 0.5ā2.0 |
| PCV (%) | 297 (100) | 49.5 Ā± 8.8 | 35ā50 |
| Total solids (mg/dL) | 297 (100) | 7.0 Ā± 1.2 | 5.4ā7.5 |
| Blood glucose (mg/dL) | 290 (97.6) | 116.8 Ā± 22.5 | 67ā132 |
| Albumin (g/dL) | 194 (65.3) | 3.5 Ā± 0.6 | 2.3ā3.9 |
| BUN (mg/dL) | 287 (96.6) | 19.8 Ā± 15.4 | 7ā32 |
| Creatinine (mg/dL) | 287 (96.6) | 1.0 Ā± 0.5 | 0.5ā1.5 |
| Na (mmol/L) | 266 (89.6) | 140.4 Ā± 7.3 | 138ā148 |
| K (mmol/L) | 269 (90.6) | 3.9 Ā± 0.6 | 3.5ā5.0 |
| Cl (mmol/L) | 263 (88.6) | 104.0 Ā± 9.3 | 105ā117 |
| pH | 45 (15.2) | 7.4 Ā± 0.1 | 7.350ā7.450 |
The mean time between admission and the initiation of fluids was 3.4 Ā± 4.8 hours. The mean times between the initiation of fluids and the start of anesthesia and start of surgery were 8.0 Ā± 12.8 hours and 8.7 Ā± 12.9 hours, respectively. The mean values for the first noninvasive systolic blood pressure, noninvasive mean arterial blood pressure, noninvasive diastolic blood pressure, and heart rate under general anesthesia were 106.3 Ā± 23.2 mm Hg, 75.8 Ā± 16.5 mm Hg, 60 Ā± 16.2 mm Hg, and 103.5 Ā± 31.2 bpm, respectively. The types of anesthetic crystalloid and synthetic colloid fluids given are listed in Table 2. The mean anesthetic fluid crystalloid rate was 6.7 Ā± 2.6 mL/kg/h. During anesthesia, 23 (7.7%) of the 297 dogs involved in the study received an anesthetic drug. Of the 23 dogs that received an anesthetic drug, 11 (47.8%) received atropine, 10 (43.5%) received dobutamine, 1 (4.3%) received dopamine, and 1 (4.3%) received norepinephrine. Only 1 (0.3%) dog received a blood transfusion during anesthesia.
Types of fluid products used during preoperative resuscitation for 297 dogs with gastrointestinal foreign body obstruction.
| Fluid products | No. (%) of dogs |
|---|---|
| Crystalloids | 297 (100) |
| āāPlasma-Lyte Aa | 269 (90.5) |
| āāLactated Ringer solutiona | 2 (0.6) |
| āāNormosol-Rb | 26 (8.8) |
| Synthetic colloids | 76 (25.6) |
| āāVetStarchc | 72 (24.2) |
| āāHespand | 4 (1.3) |
aBaxter Healthcare Corp.
bICU Medical Inc.
cZoetis Inc.
dB. Braun Medical Inc.
Of the 297 dogs diagnosed with GIFBOs, 213 (71.7%) had a solid GIFB, 71 (23.9%) had a linear GIFB, and 13 (4.4%) had a combination of linear and solid GIFBs. Of the 297 dogs, 26 (8.8%) had an intestinal perforation noted at the time of surgery. Of the 26 dogs that had gastrointestinal perforation, 14 (53.8%) had a linear foreign body, 10 (38.5%) had a solid foreign body, and 2 (7.7%) had a combination of a solid and linear foreign body. A gastrotomy was performed in 154 (51.9%) dogs and an enterotomy in 149 (50.2%) dogs, and 17 (5.7%) dogs underwent > 1 enterotomy. An enterectomy was performed in 20 of 297 dogs (6.7%), and 3 (1.0%) dogs were euthanized during surgery. All 3 (100%) dogs were euthanized intraoperatively due to severe septic peritonitis secondary to gastrointestinal perforation.
Immediate postoperative complications and whether a dog ate a meal within 24 hours were recorded in 281 dogs (Table 3). Most dogs (286 [96.3%]) survived to discharge. Of the 11 dogs that did not survive to discharge, 3 (27.3%) were euthanized intraoperatively, 3 (27.3%) were euthanized due to suspected complications secondary to septic peritonitis, 3 (27.3%) went into cardiac arrest in the postoperative period, 1 (9.0%) was euthanized due to suspected necrotizing pancreatitis, and 1 (9.0%) was euthanized due to the development of a hemoabdomen in the postoperative period. Postoperative complications were recorded at a minimum of a 7-day recheck in 273 dogs, with 50 of 273 dogs (18.3%) noted to have recorded complications. Of the 50 dogs that were recorded to have complications, 4 (8.0%) had a catastrophic complication, 19 (38.0%) had a major complication, and 28 (56.0%) had a minor complication.
Full ordered logistic regression model analysis to determine the association between categorical preoperative fluid resuscitation (< 2, 2 to ā¤ 6, and > 6 hours) and binary anesthetic and cardiovascular parameters, surgical findings, and postoperative outcomes in 297 dogs. Odds ratios > 1 indicate that the first condition of the binary independent variable (ie, yes in yes/no) resulted in increased odds of being associated with increasing preoperative fluid resuscitation. Odds ratios < 1 indicate that the first condition of the binary independent variable resulted in decreased odds of being associated with increasing preoperative fluid resuscitation.
| Variables | Population data | P value* | OR | 95% CI |
|---|---|---|---|---|
| Anesthetic interventions | ||||
| āāFluid bolus (yes/no) | 40/257 | .023 | 0.420 | 0.199ā0.887 |
| āāFluid rate (> 5 mL per h/ā¤ 5 mL per h) | 162/98 | .033 | 0.552 | 0.320ā0.953 |
| āāSynthetic colloid (yes/no) | 72/225 | .965 | 1.013 | 0.559ā1.837 |
| āāBlood product (yes/no) | 1/296 | ā | ā | ā |
| āāIO drugs (yes/no) | 23/274 | .283 | 1.692 | 0.647ā4.422 |
| Cardiovascular parameters | ||||
| āāDehydration (yes/no) | 127/170 | .106 | 1.540 | 0.912ā2.602 |
| āāNoninvasive blood pressure | ||||
| āāāSys (< 90 mm Hg/ā„ 90 mm Hg) | 46/251 | .647 | 0.816 | 0.342ā1.947 |
| āāāMAP (< 60 mm Hg/ā„ 60 mm Hg) | 39/258 | .682 | 1.206 | 0.492ā2.951 |
| āāHeart rate (< 60 or > 160 bpm/ā„ 60 and ā¤ 160 bpm) | 43/254 | .715 | 0.872 | 0.419ā1.815 |
| Surgical findings | ||||
| āāPerforation (yes/no) | 26/271 | .912 | 0.930 | 0.257ā3.359 |
| āāEnterectomy performed (yes/no) | 20/277 | .711 | 1.304 | 0.320ā5.308 |
| Postoperative outcomes | ||||
| āāVomiting (yes/no) | 9/272 | .239 | 0.350 | 0.061ā2.012 |
| āāRegurgitation (yes/no) | 67/214 | .553 | 0.834 | 0.458ā1.518 |
| āāDiarrhea (yes/no) | 42/239 | .584 | 1.224 | 0.594ā2.522 |
| āāAte within 24 h (yes/no) | 180/101 | .032 | 0.556 | 0.325ā0.951 |
| āāEuthanasia (yes/no) | 11/286 | ā | ā | ā |
| āāComplications (yes/no) | 50/222 | .382 | 0.739 | 0.375ā1.456 |
bpm = Beats per minute. IO = Intraoperative (anesthetic). MAP = Mean arterial pressure. Sys = Systolic blood pressure. ā = Data omitted due to collinearity. Bolded text represents significant values with P value < 0.05.
Preoperative fluid resuscitation length
Of the 297 dogs included in the study, 111 (37.4%), 91 (30.6%), and 95 (31.9%) were fluid resuscitated for < 2, 2 to 6, and > 6 hours, respectively. There was insufficient evidence to claim an association between the varying lengths of resuscitation groups and preoperative hydration status (P = .106), anesthetic systolic blood pressure (P = .674), anesthetic mean arterial blood pressure (P = .682), anesthetic heart rate (P = .715), anesthetic synthetic colloid use (P = .965), or use of anesthetic drugs (P = .283). Shorter preoperative fluid resuscitation was associated with higher anesthetic fluid rates (OR, 0.552; 95% CI, 0.320 to 0.953; P = .030) and anesthetic fluid boluses (OR, 0.420; 95% CI, 0.199 to 0.887; P = .023). There was insufficient evidence to claim an association between the impact of preoperative fluid resuscitation length on need for more complex intestinal surgeries (perforation, P = .912; enterectomy performed, P = .711). Dogs with shorter preoperative fluid resuscitation periods (OR, 0.556; 95% CI, 0.325 to 0.951; P = .032) were more likely to eat within 24 hours of surgery. There was insufficient evidence to claim an association between fluid resuscitation length and survival to discharge (P = .984) or postoperative complications (P = .382). The results are summarized in Table 3.
Preoperative total fluid bolus
Of the 297 dogs included in this study, 149 (50.1%) received a preoperative fluid bolus, with the mean total fluid bolus reported to be 26.7 Ā± 19.2 mL/kg. Two (0.6%) dogs received a preoperative synthetic colloid bolus as part of their fluid therapy. Of the 149 dogs that received a preoperative fluid bolus, 41 (27.5%) received < 20 mL/kg, 39 (26.2%) received 20 mL/kg, and 69 (46.3%) received > 20 mL/kg. There was insufficient evidence to claim an association between the varying amounts of preoperative total fluid bolus and preoperative hydration status (P = .097), anesthetic systolic blood pressure (P = .315), anesthetic mean arterial blood pressure (P = .865), anesthetic heart rate (P = .985), or use of anesthetic drugs (P = .516). Increased preoperative total fluid bolus was associated with anesthetic synthetic colloid use (OR, 3.15; 95% CI, 1.055 to 9.419; P = .040). Dogs that received fewer preoperative total fluid boluses (OR, 0.384; 95% CI, 0.157 to 0.939; P = .036) were more likely to eat within 24 hours of surgery. Dogs that received more preoperative total fluid boluses were less likely to have complications at the time of recheck (OR, 0.366; 95% CI, 0.139 to 0.964; P = .042). The results are summarized in Table 4.
Full ordered logistic regression model analysis to determine the association between categorical preoperative total fluid bolus (< 20, 20, and > 20 mL/kg) and binary anesthetic and cardiovascular parameters, surgical findings, and postoperative outcomes in 149 of 297 dogs. Odds ratios > 1 indicate that the first condition of the binary independent variable (ie, yes in yes/no) resulted in increased odds of being associated with increasing preoperative total fluid bolus. Odds ratios < 1 indicate that the first condition of the binary independent variable resulted in decreased odds of being associated with increasing preoperative total fluid bolus.
| Variables | Population data | P value* | OR | 95% CI |
|---|---|---|---|---|
| Anesthetic interventions | ||||
| āāFluid bolus (yes/no) | 23/126 | .602 | 0.731 | 0.226ā2.370 |
| āāFluid rate (ā¤ 5 mL per h/> 5 mL per h) | 85/49 | .957 | 0.977 | 0.425ā2.249 |
| āāSynthetic colloid (yes/no) | 36/107 | .040 | 3.153 | 1.055ā9.419 |
| āāBlood product (yes/no) | 1/219 | ā | ā | ā |
| āāIO drugs (yes/no) | 9/140 | .516 | 0.555 | 0.094ā3.280 |
| Cardiovascular parameters | ||||
| āāDehydration (yes/no) | 127/170 | .097 | 1.970 | 0.885ā4.388 |
| āāNoninvasive blood pressure | ||||
| āāāSys (< 90 mm Hg/ā„ 90 mm Hg) | 25/124 | .315 | 2.103 | 0.493ā8.969 |
| āāāMAP (< 60 mm Hg/ā„ 60 mm Hg) | 22/127 | .865 | 1.146 | 0.239ā5.499 |
| āāHeart rate (< 60 or > 160 bpm/ā„ 60 and ā¤ 160 bpm) | 24/125 | .985 | 1.010 | 0.349ā2.922 |
| Surgical findings | ||||
| āāPerforation (yes/no) | 7/142 | .329 | 4.141 | 0.239ā71.819 |
| āāEnterectomy performed (yes/no) | 4/145 | .583 | 0.436 | 0.023ā8.419 |
| Postoperative outcomes | ||||
| āāVomiting (yes/no) | 6/135 | .634 | 0.598 | 0.072ā4.941 |
| āāRegurgitation (yes/no) | 38/104 | .126 | 2.047 | 0.818ā5.125 |
| āāDiarrhea (yes/no) | 18/123 | .976 | 1.017 | 0.327ā3.159 |
| āāAte within 24 h (yes/no) | 89/52 | .036 | 0.384 | 0.157ā0.939 |
| āāEuthanasia (yes/no) | 4/145 | ā | ā | ā |
| āāComplications (yes/no) | 26/11 | .042 | 0.366 | 0.139ā0.964 |
*P < .05. ā = Data omitted due to collinearity. Bolded text represents significant values with P value < 0.05.
Preoperative fluid rate
The mean preoperative fluid rate was 133.7 Ā± 49.3 mL/kg/d. Of the 220 dogs that had preoperative fluid rates recorded, 61 (27.7%) received < 120 mL/kg/d, 86 (39.1%) received 120 mL/kg/d, and 73 (33.2%) received > 120 mL/kg/d. Dogs that were dehydrated were more likely to have an increased preoperative fluid rate (OR, 3.091; 95% CI, 1.622 to 5.892; P = .001). There was insufficient evidence to claim an association between the varying rates of resuscitation groups and anesthetic systolic blood pressure (P = .179), anesthetic heart rate (P = .076), anesthetic synthetic colloid use (P = .189), or use of anesthetic drugs (P = .463). Dogs with higher preoperative fluid rates were more likely to have hypotensive anesthetic mean arterial blood pressures (OR, 3.915; 95% CI, 1.183 to 12.946; P = .025). Increased preoperative fluid rate was also associated with decreased administration of anesthetic fluid bolus (OR, 0.319; 95% CI, 0.126 to 0.808; P = .016; Table 3). There was insufficient evidence to claim an association between preoperative fluid rates and a dog eating within 24 hours of surgery (P = .183). There was insufficient evidence to claim an association between postoperative complications and the preoperative fluid rate (P = .269). The results are summarized in Table 5.
Full ordered logistic regression model analysis to determine the association between categorical preoperative fluid rates (< 120, 120, and > 120 mL/kg/d) and binary anesthetic and cardiovascular parameters, surgical findings, and postoperative outcomes in 220 of 297 dogs. Odds ratios > 1 indicate the first condition of the binary independent variable (ie, yes in yes/no) resulted in increased odds of being associated with increasing preoperative fluid rates. Odds ratios < 1 indicate that the first condition of the binary independent variable resulted in decreased odds of being associated with increasing preoperative fluid rates.
| Variables | Population data | P value* | OR | 95% CI |
|---|---|---|---|---|
| Anesthetic interventions | ||||
| āāFluid bolus (yes/no) | 30/190 | .016* | 0.319 | 0.126ā0.808 |
| āāFluid rate (ā¤ 5 mL per h/> 5 mL per h) | 129/65 | .501 | 1.255 | 0.648ā2.431 |
| āāSynthetic colloid (yes/no) | 52/160 | .189 | 0.604 | 0.284ā1.282 |
| āāBlood product (yes/no) | 1/219 | ā | ā | ā |
| āāIO drugs (yes/no) | 18/202 | .463 | 0.673 | 0.233ā1.941 |
| Cardiovascular parameters | ||||
| āāDehydration (yes/no) | 127/170 | .001 | 3.090 | 1.621ā5.891 |
| āāNoninvasive blood pressure | ||||
| āāāSys (< 90 mm Hg/ā„ 90 mm Hg) | 34/186 | .179 | 0.469 | 0.156ā1.414 |
| āāāMAP (< 60 mm Hg/ā„ 60 mm Hg) | 31/189 | .025* | 3.915 | 1.184ā12.946 |
| āāHeart rate (< 60 or > 160 bpm/ā„ 60 and ā¤ 160 bpm) | 29/191 | .076 | 0.435 | 0.173ā1.090 |
| Surgical findings | ||||
| āāPerforation (yes/no) | 19/201 | .057 | 5.899 | 0.951ā36.613 |
| āāEnterectomy performed (yes/no) | 15/205 | .332 | 0.372 | 0.050ā2.743 |
| Postoperative outcomes | ||||
| āāVomiting (yes/no) | 9/201 | .758 | 0.771 | 0.147ā4.031 |
| āāRegurgitation (yes/no) | 58/152 | .250 | 1.503 | 0.750ā3.012 |
| āāDiarrhea (yes/no) | 29/171 | .610 | 0.801 | 0.342ā1.877 |
| āāAte within 24 h (yes/no) | 134/76 | .183 | 0.640 | 0.332ā1.233 |
| āāEuthanasia (yes/no) | 7/213 | ā | ā | ā |
| āāComplications (yes/no) | 38/166 | .269 | 0.628 | 0.275ā1.433 |
*P < .05. ā = Data omitted due to collinearity. Bolded text represents significant values with P value < 0.05.
Discussion
On the basis of the results of the current study, we partially accept the first hypothesis, as longer periods of preoperative fluid resuscitation and increased preoperative fluid rates were associated with decreased anesthetic interventions. However, increased fluid bolus amounts were associated with increased anesthetic interventions. The second hypothesis could only be partially accepted as well, as the length of preoperative fluid resuscitation and preoperative fluid rate did not impact intestinal integrity or the occurrence of postoperative complications, but decreased preoperative total fluid bolus amounts were associated with increased risk of postoperative complications.
Longer periods of fluid resuscitation prior to GIFBO surgery were associated with decreased anesthetic fluid rates and anesthetic fluid boluses and thus improved anesthetic stability. This finding likely relates to improved hemodynamic stability associated with longer periods of preoperative fluid resuscitation and their effects on preload, which is the result of venous return and venous tone. Thus, by taking the time to address a dogās hydration status prior to surgery with longer fluid resuscitation, the dogās preload and, ultimately, cardiac output are improved.7,15
In dogs diagnosed with GIFBO, increased morbidity and mortality are secondary to both traumatic injury and compromised microvascular perfusion to the intestinal wall leading to decreased intestinal viability.16 It is recommended that, prior to GIFBO surgery, patient hydration and electrolyte status be addressed prior to anesthesia. Gastrointestinal foreign body obstructions are often emergency cases in which a surgeon must determine whether a dog should undergo surgery immediately depending on the patientās clinical status. Hypotension is one of the most common and concerning adverse events that occur in anesthetized animals and is associated with increased morbidity and mortality, making appropriate fluid stabilization for GIFBO dogs even more vital to stabilization.17 However, there is often concern that patients that do not go to surgery promptly may be at higher risk for gastrointestinal injury. In Hoffman et al,18 dogs seen by a referring veterinarian and that were medically managed had a significantly longer median duration of illness (4 to 5 days) compared to untreated dogs (2 to 3 days) and were more likely to have an enterectomy performed compared to dogs that did not receive treatment prior to presentation. However, in a recent study, Maxwell et al13 compared the timing of surgical treatment (< 6 hours after presentation vs > 6 hours after presentation) with gastrointestinal injury and outcome measures, and no significant associations were noted. Rather than using time of presentation alone, this study used the length of fluid resuscitation as a time variable, and the results confirmed that preoperative fluid resuscitation length did not impact the variables associated with gastrointestinal viability (perforation occurrence and frequency of enterectomies performed).
Dogs that received a higher total preoperative fluid bolus were more likely to receive a synthetic colloid bolus during anesthesia. Synthetic colloids are indicated for companion animals with low oncotic pressures or anemia or at higher risk of bleeding due to coagulopathies.8,19 Although cautious use of synthetic colloids is recommended, fluid resuscitation with this product is effective in hypovolemic dogs with increased vascular permeability and low osmotic pressure.8 Its use is also beneficial since it increases the volume of IV fluid retention and decreases the overall use of crystalloid therapy.8,20 Preoperative dehydration did not increase the risk of patients receiving more preoperative fluid boluses; however, the mean total solids and albumin were at the higher end of normal limits (7.0 mg/dL and 3.5 g/dL, respectively) within the study population. This suggests that most of the dogs in this study, although stable, were more clinically dehydrated given that the average time between the development of clinical signs and presentation was 56.7 hours. These dogs may have been more likely to receive a synthetic colloid due to a combination of higher fluid rates and protein losses from their gastrointestinal and vascular systems requiring additional oncotic support during anesthesia to provide hemodynamic stability.
Additionally, both shorter preoperative fluid resuscitation periods and fewer preoperative total fluid boluses were associated with dogs eating sooner postoperatively. This is similar to the Maxwell et al13 study in which dogs with immediate surgical intervention were reported to eat earlier compared to dogs with delayed surgical intervention (> 6 hours after presentation). Dogs with a shorter duration of clinical signs are less likely to have systemic illness associated with fluid and electrolyte imbalances, compromised blood supply to the intestine, intestinal wall edema and necrosis, or increase in pathogenic intraluminal bacteria.2,6 It has been reported in human literature that high volume resuscitation may alter hydrostatic and oncotic pressure differentials leading to the formation of intestinal edema.21,22 The result of these pressure changes can lead to decreased intestinal contractile activity and postoperative ileus and gastrointestinal tract dysfunction causing inappetence in a patient.22 This suggests that the association between shorter fluid resuscitation and eating sooner postoperatively may be due to these dogs being less clinically affected and therefore not requiring extensive fluid resuscitation or more complex surgical treatment.
Dogs with higher preoperative fluid rates were more likely to have hypotension associated with anesthetic mean arterial blood pressure. Mean arterial blood pressure is the product of cardiac output and total systemic vascular resistance and is directly affected by these 2 factors.23 In cases with substantial dehydration, cardiac output may decline due to a reduction in left ventricular filling, thus leading to a lower mean arterial pressure.17,23 In this study, preoperative fluid rate was the only fluid resuscitation parameter that was also associated with dehydration. This suggests that the dogs receiving a higher preoperative fluid rate were likely more clinically affected at the time of presentation, leading to an increased risk of hypotension associated with mean arterial pressure under anesthesia.
The limitations of this study included its retrospective nature, variance in preoperative care, and short postoperative follow-up time. Since there is no single defined value to determine anesthetic stability, anesthetic cardiovascular parameters (eg, blood pressure and heart rate) and interventions were used as indicators of anesthetic stability for this study. An additional consideration of this study is that anesthetic depth and specific medications may have influenced the initial induction cardiovascular parameters collected and anesthetic interventions used to evaluate anesthetic stability. Ideally, a standardized anesthetic protocol would help control this variability but was not feasible due to the retrospective nature of the study. Another limitation was that dogs were categorized on the basis of their preoperative fluid resuscitation times and the volume of fluids received in the preoperative period. However, this grouping does not consider the level of cardiovascular stability or dehydration at the time of presentation. Ideally, the level of dehydration at the time of presentation should be considered when discussing hemodynamic stability; however, a percent dehydration value was not consistently reported within the medical record for each patient. Future studies prospectively evaluating companion animalsā hydration status prior to fluid management and surgical intervention would be beneficial in determining the impact of preoperative fluid resuscitation length on anesthetic stability. We acknowledge that the study would have been stronger if we had drawn definitive recommendations regarding optimal fluid resuscitation prior to anesthesia. However, based on the variability of the study population and standard of care during resuscitation, it is especially difficult to give exact recommendations for fluid resuscitation time, rate, and amounts prior to surgery to decrease anesthetic interventions and improve overall stability. Ideally, future studies would control these factors to help determine the optimal fluid resuscitation for GIFBO dogs prior to undergoing anesthesia.
In conclusion, dogs with shorter fluid resuscitation were associated with higher anesthetic fluid rates and increased anesthetic fluid boluses. Thus, longer fluid resuscitation periods may be associated with fewer anesthetic interventions during surgery. Also, dogs with shorter fluid resuscitation were associated with eating within 24 hours in the postoperative period; however, this is most likely associated with mild clinical signs and less complex surgical intervention. Although the overall impact of longer fluid resuscitation on anesthetic stability and postoperative complications should be further evaluated in future studies, the results of this study suggest that longer fluid resuscitation periods may be beneficial for decreasing anesthetic interventions prior to GIFB surgery without compromising the integrity of the gastrointestinal tract.
Acknowledgments
None reported.
Disclosures
Results of this study were presented at the residentsā poster competition at the 2023 American College of Veterinary Surgeons Surgery Summit, October 12 to 14, 2023, Louisville, Kentucky.
Drs. Risselada and Moore are members of the JAVMA Scientific Review Board, but were not involved in the editorial evaluation of or decision to accept this article for publication.
No AI-assisted technologies were used in the generation of this manuscript.
Funding
The authors have nothing to disclose.
ORCID
M. Risselada https://orcid.org/0000-0003-1990-4280
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