Chapter 41 - Postoperative care, complications Flashcards
What is a common postoperative complication in horses suffering from strangulating small intestine disease?
Ileus
What syndrome is frequently associated with exaggerated immune responses in horses with GI disease?
SIRS (Systemic Inflammatory Response Syndrome)
What is a frequent cause of systemic inflammatory response syndrome in horses with GI disease?
Endotoxemia
Which organ systems are at increased risk of dysfunction in horses with SIRS?
Pneumonia and renal failure
What should postoperative monitoring for GI disease include in addition to physical examinations?
Clinical pathologic assessment
What are the key indicators to be monitored postoperatively in horses with GI disease?
- Pain,
- mucous membrane color,
- heart rate,
- respiratory rate,
- urine/fecal production,
- extremities,
- temperature
What gastrointestinal parameters are essential to evaluate postoperative GI function?
- Appetite, GI sounds,
- fecal production,
- fecal consistency
What is often used to investigate poor postoperative GI response in horses?
- Nasogastric intubation,
- rectal palpation,
- abdominal ultrasonography
What factor increases the frequency of monitoring in postoperative horses with GI disease?
Strangulating lesions
What are two undesirable side effects of NSAIDs in postoperative horses?
- Gastrointestinal ulceration
- nephrotoxicity
Which enzyme does COX-2 selective NSAIDs target to reduce inflammation?
COX-2 (Cyclooxygenase 2)
What synthetic opiate is used to control postoperative pain in horses?
Butorphanol dose 13 microgram/kg/hr in CRI
What is the classification of butorphanol?
Butorphanol is a mu opioid antagonist with low intrinsic activity and kappa opioid agonist exhibiting high affinity.
What is the loading dose of lidocaine for postoperative ileus management in horses?
1.3 mg/kg IV followed by 0.05 mg/kg/min IV
What plasma-derived therapy binds circulating endotoxin in horses with SIRS?
Hyperimmune plasma 20–40 mg/kg BW
What therapy is used to prevent laminitis in horses with SIRS?
Digital cryotherapy
At what temperature should the digits be cooled to reduce laminitis risk in horses with SIRS?
4°C
NSAID, frozen hyeprimune plasma and__________which bind circulating endotoxin and may provide some clinical benefit
Polymyxin B 1000–6000 IU/kg q 8–12 hours IV
What adverse effects can occur due to lidocaine toxicity in horses?
Muscle tremors, altered visual function, anxiety, ataxia, collapse
Lidocaine toxicity can be exacerbated with concomitant use of higlhy protein bound drugs such as
ceftiofur
How does it work Lidocaine?
Lidocaine prevents propagation of action potentials by binding to sodium channels, and may exert prokinetic effects through smooth muscle membrane alteration
Lidocaine has also been shown to ameliorate the inhibitory effects of flunixin meglumine on ______________ of the _____________ (2w)
recovery of the mucosal barrier
What 2 drugs are more selective to inhibit the COX-2 but not COX-1?
meloxicam and firocoxib
What are common postoperative electrolyte imbalances in horses?
K+, Ca2+, Mg2+
What is the daily fluid maintenance requirement for adult horses?
50-60 mL/kg
How much fluid do foals need daily?
70-80 mL/kg
What organ is responsible for recovering a large volume of water in horses?
Large colon
Which solution contains calcium and lactate as a buffer?
Lactated Ringer solution
What is the goal of therapy in horses with severe SIRS postoperatively?
Maintain vascular volume
What heart rate is a reasonable indicator of adequate vascular volume?
< 80 beats/min
At what PCV should therapy be adjusted in horses postoperatively?
< 50%
What total protein level indicates the need for colloid administration?
< 4.1 g/dL
What colloids are available for administration to horses?
Plasma,
dextrans,
hydroxyethyl starch (voluven)
What is the half-life of potassium penicillin in horses?
80 minutes
How often is potassium penicillin administered perioperatively?
Every 6 hours
What is the typical dose for gentamicin in horses postoperatively?
6.6 mg/kg IV
What postoperative duration of antimicrobials showed no difference in infection rates?
3 vs. 5 days
How soon can feeding be resumed after surgery in small intestinal disorders?
12 hours
When can feeding be resumed after surgery in large colon disorders?
6-8 hours
What laxative is recommended postoperatively for impactions?
Mineral oil
What percentage of horses experience recurrent abdominal pain postoperatively?
28-30%
What GI procedure is associated with a higher prevalence of postoperative colic?
Small intestinal resection
Within how many hours post-surgery does colic due to original lesion recurrence occur?
72 hours
What are common nongastrointestinal sources of postoperative abdominal pain?
Peritonitis, surgical incision pain
What causes of postoperative colic are likely 5 to 7 days after surgery?
Adhesions, recurrence, new GI lesion
What diagnostic tools help in postoperative decision-making for colic?
Physical exam, rectal palpation, ultrasonography
What can be challenging to differentiate post-surgery in horses?
Ileus vs. intestinal obstruction
What is a common treatment for postoperative colic without second surgery?
Medical therapy, NSAIDs, spasmolytics
What spasmolytic medication can be used in postoperative colic treatment?
N-butylscopolammonium bromide
What is the most common reason for postoperative death in horses?
Postoperative colic
What is the suggested prognosis for horses experiencing colic within 48 hours post-surgery?
Good with medical therapy
What increases the risk of postoperative death or euthanasia in horses?
Postoperative colic
What major fluid loss problem occurs with large colon volvulus?
Capillary permeability increase
What is the oncotic pressure threshold below which colloids should be administered?
12 mm Hg
What factor should be monitored every 6 hours postoperatively in horses with fluid loss?
PCV, TP
How long does it take for capillary permeability to be restored in surviving horses?
24-36 hours
What syndrome delays feeding resumption in large colon torsion cases?
Systemic inflammatory response syndrome (SIRS)
What factor is a common dilemma postoperatively in horses with colic?
Distinction between ileus and obstruction
What is the common term for motility dysfunction of the small intestine in horses after GI surgery?
Postoperative Ileus (POI)
What range of prevalence is reported for POI in horses undergoing all types of colic surgeries?
9.6% to 21%
What range of POI-associated death or euthanasia is reported in studies?
30% to 76%
Which condition often leads to POI in horses?
Small intestine strangulating lesions
How many liters of reflux at admission is a risk factor for developing POI?
More than 8 L
What duration of anesthesia increases the risk of POI?
More than 2.5 hours
Which surgical procedure reduces the risk of developing POI?
Small intestine strangulating lesions
What substance is administered intraoperatively to decrease the risk of POI?
Lidocaine
What age is considered a risk factor for developing POI in horses?
Greater than 10 years
What is a common clinical sign of POI due to gas and fluid accumulation in the intestines?
Gastric distention
Which breed of horse is more prone to developing POI?
Arabian
What abdominal surgery often leads to POI besides small intestine procedures?
Large colon volvulus
What hematologic paramete is a risk factor for POI?
PCV higher than 45%
What is a common electrolyte imbalance seen in POI?
Low K+ and Cl−
Which inflammatory mediator is implicated in motility disruption during POI?
Prostaglandin E2 (PGE2)
What is the primary physiological disruption that leads to POI?
Sequestration of fluid, gas, and ingesta
What inflammatory mediator, besides prostaglandins, disrupts motility in POI?
Tumor Necrosis Factor (TNF)
Within how many hours post-anesthesia does gastric distention typically occur in POI?
12 to 48 hours
What common symptom indicates pain from GI distention in horses with POI?
Flank watching
Which prokinetic drug has shown potential benefit but requires further trials?
Neostigmine
What neurotransmitter is involved in excitation of GI smooth muscle in horses?
Substance P (SP)
Which neurotransmitter inhibits GI smooth muscle activity during POI?
Nitric Oxide (NO)
What type of cells help mediate contractility in the GI system and are affected during POI?
Interstitial cells of Cajal
What receptor antagonist is identified as a potential treatment in human POI?
Mu receptor antagonist
Which pharmacologic agents have limited clinical evidence for efficacy in POI treatment?
Erythromycin and cisapride
What parasympathomimetic agent has historically been used to increase GI motility in POI?
Bethanechol
What is Bethanechol chlorid?
muscarinic cholinergic agonist (cholinomimetic or parasympathomimetic that stimulates ACh receptors (1arly M3 but also M2 receptors on GI smooth muscles at the levels of myenteric plexus causing GI contractile activity
Which intravenous drug, besides NSAIDs, is used for its anti-inflammatory properties in POI?
Lidocaine
What condition must be ruled out if a horse does not respond to POI treatment within 48 hours?
Mechanical obstruction
Jacobs et al 2019 VS Use of perioperative variables to determine the requirement for repeat celiotomy in horses with postoperative reflux after small intestinal surgery - What perioperative variable was NOT found to be associated with a surgical reason for postoperative reflux (POR) after small intestinal (SI) surgery in horses?
A) Postoperative fever
B) Timing of colic in the postoperative period
C) Greater volume of POR
D) Timing of POR resolution
C) Greater volume of POR
What was considered a medical reason for POR in horses after SI surgery?
A) Anastomosis complications
B) Mechanical obstruction
C) Nonviable intestine
D) Resolution of POR with medical management or no surgical reasons found at repeat surgery/necropsy
D) Resolution of POR with medical management or no surgical reasons found at repeat surgery/necropsy
According to the study, which of the following variables indicated a higher likelihood of a surgical reason for POR after SI surgery?
A) Duration of POR
B) Presence of a postoperative fever
C) Low volume of reflux
D) Normal rectal temperature
B) Presence of a postoperative fever and colic
Historically, pharmacologic modulation of GI motility in the horse has been directed at increasing excitatory cholinergic activity with administration of parasympathomimetic agents, name 2
bethanechol or neostigmine
In addition to being affected by sympathetic and parasympathetic input, contractility of GI muscle is directly mediated by enteric inhibitory neurotransmitters such as
- vasoactive intestinal peptide (VIP),
- adenosine triphosphate (ATP),
- nitric oxide (NO),
- calcitonin gene-related peptide (CGRP),
- and enteric excitatory neurotransmitters such as substance P (SP)
- and acetylcholine (ACh).
What type of drug is Bethanechol?
A) Adrenergic agonist
B) Cholinergic agonist
C) Dopamine antagonist
D) Serotonin agonist
B) Cholinergic agonist
Which receptor does Bethanechol primarily stimulate to cause gastrointestinal contractile activity?
A) M1 receptors
B) M2 receptors
C) M3 receptors
D) Nicotinic receptors
C) M3 receptors
Bethanechol has been shown to increase contractile activity in which sections of the horse’s GI tract?
A) Stomach and jejunum
B) Duodenum, jejunum, cecum, and pelvic flexure
C) Pelvic flexure and ileum
D) Cecum and large colon
B) Duodenum, jejunum, cecum, and pelvic flexure
In normal horses, what effect does Bethanechol have on gastric and cecal emptying?
A) Delays emptying
B) Increases the rate of emptying
C) Decreases motility
D) Causes ileus
B) Increases the rate of emptying
In a postoperative ileus (POI) model in ponies, Bethanechol combined with which drug shortened transit time?
A) Yohimbine
B) Acepromazine
C) Cisapride
D) Neostigmine
A) Yohimbine
Which drug was more effective than Bethanechol in restoring coordinated gastroduodenal motility patterns in a POI model in ponies?
A) Acepromazine
B) Yohimbine
C) Neostigmine
D) Metoclopramide
D) Metoclopramide
What is the recommended dosage of Bethanechol in horses?
A) 0.05 mg/kg SC every 3-4 hours
B) 0.025 mg/kg SC every 3-6 hours
C) 0.01 mg/kg IV every 6-8 hours
D) 0.1 mg/kg IM every 12 hours
B) 0.025 mg/kg SC every 3-6 hours
What are the most common side effects of Bethanechol?
A) Hypertension and tachycardia
B) Abdominal cramping and diarrhea
C) Respiratory depression and nausea
D) Dry mouth and constipation
B) Abdominal cramping and diarrhea
Neostigmine works as a prokinetic by:
A) Blocking dopamine receptors
B) Retarding the breakdown of acetylcholine
C) Stimulating serotonin release
D) Inhibiting norepinephrine synthesis
B) Retarding the breakdown of acetylcholine
Neostigmine delays gastric emptying and decreases motility in which GI section?
A) Cecum
B) Stomach and jejunum
C) Pelvic flexure
D) Duodenum
B) Stomach and jejunum
What effect does Neostigmine have on the pelvic flexure in horses?
A) Decreases motility
B) Increases propulsive motility
C) Causes distention
D) Reduces contractions
B) Increases propulsive motility
Which of the following is a side effect commonly seen with Neostigmine use?
A) Excitement
B) Abdominal pain
C) Hypotension
D) Tachycardia
B) Abdominal pain
What is the recommended initial dosage of Neostigmine for horses?
A) 0.022 mg/kg IV
B) 0.01 mg/kg SC
C) 2 mg/adult horse SC
D) 1 mg/adult horse IM
C) 2 mg/adult horse SC
Adrenergic antagonists like Acepromazine are used based on the assumption that:
A) Parasympathetic hyperactivity contributes to POI
B) Sympathetic hyperactivity contributes to POI
C) Dopamine inhibits GI motility
D) Acetylcholine enhances GI motility
B) Sympathetic hyperactivity contributes to POI
Which of the following drugs is a selective α2-adrenergic antagonist?
A) Acepromazine
B) Metoclopramide
C) Yohimbine
D) Neostigmine
C) Yohimbine
Metoclopramide’s prokinetic effects result from antagonism of which receptors?
A) 5-HT4 and DA2
B) M3 and DA1
C) 5-HT3 and M2
D) M3 and 5-HT2
A) 5-HT4 and DA2
Which neurotransmitter’s release is inhibited by stimulation of α2-receptors?
A) Serotonin
B) Dopamine
C) Norepinephrine
D) Acetylcholine
D) Acetylcholine
In a POI model in ponies, Metoclopramide was more effective in restoring GI coordination compared to:
A) Cisapride
B) Bethanechol
C) Yohimbine
D) Acepromazine
B) Bethanechol
What is the main prokinetic activity of Metoclopramide in horses?
A) Dopamine receptor stimulation
B) Serotonin receptor antagonism
C) Acetylcholine release inhibition
D) Stimulating in vitro circular muscle contractility
D) Stimulating in vitro circular muscle contractility
What is the common dosage of Metoclopramide in horses when administered IV?
A) 0.01 mg/kg over 20 minutes
B) 0.1 mg/kg over 10 minutes
C) 0.25 mg/kg diluted in 500 mL of saline over 30-60 minutes
D) 0.5 mg/kg diluted in 200 mL of saline over 15 minutes
C) 0.25 mg/kg diluted in 500 mL of saline over 30-60 minutes
Metoclopramide can cause which side effect in horses?
A) Bradycardia
B) Excitement and restlessness
C) Respiratory depression
D) Abdominal bloating
B) Excitement and restlessness
Cisapride’s prokinetic effect is primarily mediated through which receptor agonism?
A) 5-HT4
B) DA2
C) M3
D) α2
A) 5-HT4
Why was Cisapride taken off the human market in most countries?
A) Lack of efficacy
B) Cardiovascular toxicities
C) Gastrointestinal side effects
D) Poor absorption
B) Cardiovascular toxicities
Tegaserod acts on which receptor to enhance GI motility?
A) 5-HT4
B) 5-HT2
C) DA2
D) M2
A) 5-HT4
Which of the following effects does Cisapride have in horses?
A) Increases motility in the cecum only
B) Decreases gastric emptying
C) Stimulates coordinated activity in the ileocecocolonic junction
D) Reduces myoelectric activity in the colon
C) Stimulates coordinated activity in the ileocecocolonic junction
What effect does Tegaserod have in normal horses?
A) Delays gastric emptying
B) Increases GI transit time
C) Reduces gut sounds
D) Reduces the frequency of defecation
B) Increases GI transit time
What dosage of Tegaserod was found appropriate to reach therapeutic concentrations in normal horses?
A) 0.1 mg/kg PO BID
B) 0.5 mg/kg IV BID
C) 0.27 mg/kg PO BID
D) 0.02 mg/kg IV BID
C) 0.27 mg/kg PO BID
Which receptor is not functionally present in the equine jejunum?
A) 5-HT4
B) M2
C) DA1
D) 5-HT1a
A) 5-HT4
Which drug combination was effective in reducing the severity of POI in horses?
A) Metoclopramide and Yohimbine
B) Bethanechol and Neostigmine
C) Bethanechol and Yohimbine
D) Cisapride and Neostigmine
C) Bethanechol and Yohimbine
What effect does Yohimbine have on cholinergic neurons?
A) Stimulates α2-receptors
B) Inhibits norepinephrine synthesis
C) Enhances acetylcholine release
D) Blocks serotonin release
C) Enhances acetylcholine release
Which drug causes extrapyramidal side effects such as excitement and restlessness in horses?
A) Cisapride
B) Tegaserod
C) Metoclopramide
D) Neostigmine
C) Metoclopramide
Which drug has been associated with cardiovascular toxicities in humans, limiting its availability?
A) Tegaserod
B) Metoclopramide
C) Yohimbine
D) Acepromazine
A) Tegaserod
What is a contraindication for using Neostigmine in horses?
A) Cecal impaction
B) Gastric motility issues
C) Ileal obstruction
D) Small intestinal distention
D) Small intestinal distention
Acepromazine maleate is what type of adrenergic antagonist?
A) α1-selective
B) α2-selective
C) Nonselective α-adrenergic
D) Nonselective β-adrenergic
C) Nonselective α-adrenergic
Which prokinetic drug works by blocking dopamine receptors and stimulating serotonin receptors?
A) Metoclopramide
B) Cisapride
C) Tegaserod
D) Neostigmine
A) Metoclopramide
What is the main concern with the use of adrenergic antagonists as prokinetics in equine clinical cases?
A) Lack of efficacy
B) Cardiovascular side effects
C) Increased risk of POI
D) Excessive smooth muscle contractio
D) Excessive smooth muscle contraction
Which prokinetic drug has been shown to significantly decrease the incidence of POI in horses in clinical trials?
A) Neostigmine
B) Cisapride
C) Bethanechol
D) Yohimbine
B) Cisapride
what type of drug is N-methylnaltrexone?
Opioid antagonist
What does N-methylnaltrexone directly stimulate in vitro?
Jejunal muscle strips
What dose of N-methylnaltrexone attenuates the effects of morphine in horses?
0.75 mg/kg IV BID
hat effects does N-methylnaltrexone have when administered with morphine?
Increases defecation frequency
Increases fecal weight
Prevents increased transit time
Which receptor does Alvimopan act on?
Mu receptor
Why is Alvimopan potentially less useful in horses?
Differences in POI pathophysiology
