U4 O1 - Gastrointestinal and Medical Abdominal Emergencies Flashcards
What is melaena?
Melaena
Altered/partially digested blood in the faeces – faeces often appear black.
What is tenesmus?
Tenesmus
Straining to defaecate or urinate- often repeated, ineffective attempts to urinate/ defaecate.
What is regurgitation?
Regurgitation
A passive process where undigested or partially digested food or liquid is expelled from the oesophagus/or stomach. There are no prodromal signs, muscular contractions or abdominal effort
What is vomiting?
Vomiting
This is a reflex, forceful, expulsion of stomach or upper small intestinal contents via the mouth. There will be prodromal signs (swallowing, retching, salvation etc.). The act of vomiting includes abdominal muscular contractions.
What is haematemesis?
Haematemesis
Vomiting blood
What is dysphagia?
Dysphagia
Difficulty eating or swallowing.
Why can fluid build up in body cavities?
An abnormal collection of fluid can sometimes arise in the pleural, peritoneal, or pericardial space secondary to disease or injury.
There are various underlying causes of this fluid accumulation. It is important to analyse the fluid in order to identify the underlying cause of the fluid accumulation. This involves integrated
assessment of physical (e.g. SG, colour, smell) appearance, turbidity and cytologic characteristics (e.g. high cellularity, intracellular bacteria) etc.
What is transudate?
A fluid, in the pleural, peritoneal, or pericardial space,
that has passed through a membrane (e.g. capillary
membrane) usually as a result
of imbalanced hydrostatic and osmotic forces e.g. venous stasis
secondary to congestive cardiac failure. The fluid is usually low
in protein with a relatively low cell count.
What is modified transudate?
A modified transudate is like a transudate but tends to have a slightly higher protein level and be more cellular. If a transudate has been present for some time, it can start to cause irritation to the membrane lining the cavity e.g. peritoneum. This can result in
a low-grade inflammatory response with increased protein and inflammatory cells. Possible causes of a modified transudate are portal hypertension, congestive cardiac failure or neoplasia
What is exudate?
A fluid, in the pleural, peritoneal, or pericardial space with a relatively high protein level and cell count, that is usually caused by an underlying inflammatory process. The fluid arises due to increased capillary permeability associated with an inflammatory
process.
What is chylous effusion?
This is a type of transudate with a relatively high fat content. It is more commonly seen in a patient with a pleural effusion than a peritoneal effusion. It can be idiopathic, arise secondary to congestive cardiac failure or damage to the thoracic duct
What is a haemorrhagic effusion?
An effusion which contains a measurable amount of red blood cells (PCV >1). It can be secondary to trauma, rodenticide intoxication, neoplasia or coagulopathy
What is a Sanguinous effusion?
This is an effusion that looks blood-stained but has a lower red blood cell count which is not measurable (< 1%)
What is a Uroabdomen/uroperitoneum?
A low protein relatively low cellular fluid at least initially. Caused by trauma, urolithiasis, neoplasia or inflammation in urinary tract.
The protein and cell count increase the longer that urine is present in the abdomen due to the irritant effect. The creatinine and potassium levels are likely to be greater than serum levels.
What is peritonitis?
Inflammation of the serosal membrane that lines the abdominal cavity (peritoneum). Can be primary or secondary e.g. feline infectious peritonitis (FIP).
What is a Septic abdomen/peritonitis?
Infection of the peritoneal cavity with a pathogenic organism. Can be primary (less common e.g. haematogenous spread) or secondary (more common e.g. intestinal perforation)
What is regurgitation and what is it usually associated with?
Regurgitation is the passive expulsion of food and/or fluid from the oesophagus (and/ or stomach). It is associated with oesophageal disease – usually intrathoracic
What complication can be associated with regurgitation?
Aspiration pneumonia is relatively common in association with oesophageal disease.
Because, understandably, it may be hard for an owner to differentiate vomiting from regurgitation, a patient with oesophageal disease/injury may present with a history of acute ‘vomiting’
Awareness of the potential for aspiration pneumonia should always be an important nursing consideration in a patient that is regurgitating.
What type of patients are higher risk for aspiration pneumonia?
Patients with acquired megaoesophagus, brachycephalic patients and patients with laryngeal paralysis are amongst the patients at a higher risk of aspiration.
What may regurgitation occur secondary to?
Regurgitation may occur secondary to oesophageal injury (e.g. oesophagitis); mechanical, obstructive lesions (e.g. tumour, stricture, vascular ring anomaly) or functional (motility) abnormalities (e.g. Myasthenia gravis)
Clinically what does regurgitation need to be differentiated from?
Clinically, regurgitation needs to be differentiated from gagging, retching and vomiting.
What is gagging often associated with?
Gagging is often associated with pharyngeal disease.
What can oesophagitis develop secondary to?
Oesophagitis can sometime develop secondary to prolonged vomiting associated with gastric disease, but these patients are likely to be vomiting too. Any patient with ileus, of any cause, may present with regurgitation.
What can be the cause of regurgitation in cats?
Feline dysautonomia and myasthenia gravis can cause megaoesophagus; congenital megaoesophagus can affect Siamese cats; long haired breeds may regurgitate secondary to fur balls; and a cat with a thymic or mediastinal mass may develop regurgitation secondary to compression of the oesophagus. Cats may also be affected by oesophageal tumours, strictures, oesophagitis etc
What 3 body systems can be the cause of regurgitation?
oesophageal/pharyngeal disease
neuromuscular disease
endocrine
What type of oesophageal/pharyngeal disease be the cause of regurgitation?
Megaoesophagus oesophagitis obstruction - foreign body stricture mass vascular ring anomaly hiatus hernia gasto-oesophageal intususseption
What type of Neuromuscular disease be the cause of regurgitation?
Myasthenia gravis Tetanus Botulism dysautonomia polyneuropathy
What type of endocrine disease be the cause of regurgitation?
hypothyroidism
hypoadrenocorticism
What other signs may be seen with regurgitation if the patient had aspirated?
There may also be coughing, weakness, fever and respiratory signs, secondary to concurrent
aspiration pneumonia. Animals with regurgitation will be predisposed to developing aspiration pneumonia since they are unable to protect their airway.
What other signs may be seen with regurgitation if the patient has a neuromuscular disease?
A patient with generalised neuromuscular disease may also have exercise intolerance/collapse
What other signs may be seen with regurgitation if a feline patient has dysautonomia?
A cat with feline dysautonomia (Key-Gaskell syndrome) will have additional clinical signs associated with this condition e.g. mydriasis, constipation.
A presumptive diagnosis of feline dysautonomia is often made based on clinical signs. However to obtain a definitive diagnosis tissue samples are required. Cats that are severely affected carry a grave prognosis.
What blood tests should be run on a patient with regurgitation and what can this help to identify?
A minimum database of haematology (PCV, blood smear etc.), biochemistry and urinalysis is advised (Garosi, 2013). Bloodwork may reveal abnormalities consistent with an underlying disease process (e.g. ↑ K and ↓ Na with hypoadrenocorticism); or aspiration pneumonia (neutrophilia with left shift). A patient with a pyloric outflow obstruction, for example, may have regurgitation alongside vomiting due to mechanical obstruction of food outflow. However, the blood results for this patient may show a hypochloraemic, hypokalaemic metabolic alkalosis caused by vomiting of stomach origin.
What can radiography on a regurgitating patient help to determine?
Thoracic radiography is of great value in animals with regurgitation if it can be performed without risk to the patient. It can confirm the presence and extent of a
megaoesophagus; and the presence and location of radiopaque foreign bodies.
Depending on the underlying cause of the regurgitation, signs of aspiration pneumonia
and pneumomediastinum may also be apparent. When trying to confirm the presence of megaoesophagus, radiography should ideally be performed in the conscious patient, as general anaesthesia can lead to radiographic signs of megaoesophagus associated with muscle relaxation and the agents used
How should a patient with regurgitation be positioned for radiography?
The patient should be positioned carefully for a lateral view, with the head elevated, ideally, by using a tilted table. If the patient starts to regurgitate it should be moved immediately to sternal recumbency to reduce the chance of aspiration occurring. A positive contrast study e.g. barium meal may be required to confirm the cause of the regurgitation. N.B. Barium sulphate should NOT be administered if there is any possibility of an alimentary perforation and it should only be administered to a conscious patient. Great care MUST be taken to prevent regurgitation and aspiration
following the administration of barium sulphate
If radiography can not be performed in a conscious patient with regurgitation what can be done?
a regurgitating patient is a higher risk of aspiration
pneumonia. Therefore, if radiography cannot be performed in the conscious patient, a rapid sequence general anaesthetic induction and intubation is a safer option than sedation and leaving the patient with an unprotected airway. The RVN should ensure
that suction is available, the animal is induced in sternal recumbency and the airway is secured as quickly as possible. Careful monitoring throughout the procedure and into recovery is vital.
Ultrasound examination can also provide diagnostic information e.g. presence of an oesophageal mass. It is non-invasive and does not require sedation or anaesthesia.
However, identifying abnormalities of the oesophagus may be challenging- therefore a combination of diagnostics is normally indicated.
POCUS can also highlight areas of pulmonary consolidation which may be indicative
of aspiration pneumonia.
Further investigation might involve specific tests such as ‘a thyroid panel’ or an ACTH stimulation test may be performed; identifying antibodies to acetylcholine (Ach) receptor sites will aid a diagnosis of myasthenia gravis (Garosi, 2013).
Advanced diagnostics such as oesophagoscopy and fluoroscopy may also be performed
What is the main focus of nursing care for a patient with regurgitation?
Treatment will be focused on the underlying cause (e.g. removal of the foreign body, treatment for hypoadrenocorticism etc.). Nursing care is extremely important for animals with megaoesophagus- ensuring adequate nutrition and preventing comorbidities developing such as aspiration pneumonia. Megaoesophagus is discussed in more detail later in this outcome (4.1.7). Regular ongoing assessments are indicated even once the underlying cause has been identified and resolved as patients may
develop aspiration pneumonia after this point.
What is vomiting?
Vomiting is not a diagnosis but a clinical sign- there are lots of different causes. Whilst chronic vomiting is common, emergency presentations are often due to acute onset vomiting with large volumes of fluid lost or vomiting of blood, for example. Depending on the
underlying cause, acute or chronic diarrhoea may also be present. The patient may have mild clinical signs and a self-limiting condition. However, a patient with excessive vomiting can present with hypovolaemia and electrolyte derangements due to excess
fluid loss. Vomiting is often associated with an underlying problem e.g. intestinal foreign body/ pancreatitis and may be an early sign of a severe underlying problem (e.g. septic peritonitis). The presence of blood in vomit is usually a serious finding – depending on the underlying cause it may be fresh blood (haematemesis) or digested blood (melaena). Small flecks of blood may sometimes be present in a patient with acute vomiting due to damage to the gastric mucosa
What conditions can vomiting be associated with?
The vomiting may be of gastro-intestinal tract (GIT) origin e.g. gastritis, foreign body etc. - most cases
are dietary in origin e.g. scavenging. Vomiting, however, can also be associated many other infectious and non-infectious conditions -
• Neurological disease e.g. vestibular syndrome
• Liver disease
• Renal disease
• Endocrine disease e.g. hypoadrenocorticism, diabetic ketoacidosis (DKA)
• Pancreatic disease
• Toxicity
• Infectious e.g. Parvo virus, Salmonella, Campylobacter etc.
• Neoplastic
• Pericardial effusion (vomiting may occur 24-48 hours before acute cardiovascular signs
• Coagulopathy e.g. haematemesis, melaena
Why is signalment and history important in helping to identify the likely cause of vomiting?
The signalment and history are important in helping to identify the likely cause of vomiting and provide appropriate treatment e.g. a young dog which scavenges has increased likelihood of foreign body; an unvaccinated, young dog may have parvoviral
enteritis; an old cat with weight loss, PUPD and halitosis is more likely to have chronic renal failure.
It is useful to try and identify the time course, the frequency of vomiting and the nature of the vomitus as this can indicate a possible cause/ level of seriousness in some cases.
How can the colour of the vomit suggest which part of the GIT it could have arisen from?
The colour of the vomit can suggest which part of the GIT it could have arisen from and can, sometimes, indicate the seriousness of the problem e.g.
➢ clear – could be swallowed saliva
➢ yellow - could be bile that has refluxed into the stomach
➢ green- could be undigested bile that has built up in the upper duodenum due to an intestinal obstruction or ileus
➢ brown (with foul, fetid smell) – could be from small intestine secondary to complete intestinal obstruction ➢ red – fresh blood in vomit
➢ coffee grounds – altered blood in vomit
What could clear vomit indicate?
➢ clear – could be swallowed saliva
What could yellow vomit indicate?
➢ yellow - could be bile that has refluxed into the stomach
What could green vomit indicate?
➢ green- could be undigested bile that has built up in the upper duodenum due to an intestinal obstruction or ileus
What could brown (foul, fetid smell) vomit indicate?
➢ brown (with foul, fetid smell) – could be from small intestine secondary to complete intestinal obstruction
What could red vomit indicate?
➢ red – fresh blood in vomit
What could coffee grounds vomit indicate?
➢ coffee grounds – altered blood in vomit
What is it important to assess when a patient is admitted for vomiting and why?
The cardiovascular system should be thoroughly assessed to determine if there is any compromise (i.e. decreased perfusion which may be caused by
hypovolaemia or distributive shock). A patient with acute vomiting can lose a large volume of fluid and electrolytes over a short time course. The respiratory rate and pattern might be abnormal secondary to acid-base derangements e.g. acidosis. As well as assessing whether the patient is hypovolaemic, it is important to assess the hydration status- IVFT will be required for hypovolaemic and dehydrated patients. The
patient’s position and abdominal musculature may suggest abdominal pain e.g. praying position/ guarded abdomen. Not only will signs of abdominal pain influence the treatment plan on welfare grounds e.g. analgesia, but the underlying cause will also need to be identified as pain may be associated with a ‘surgical abdomen’ e.g. perforation.
Why might a metabolic acidosis or alkalosis occur with a vomiting patient?
A metabolic acidosis may be present due to loss of fluid from the vomiting - with the progressive dehydration, resultant hypovolaemia and anaerobic respiration, lactic acid is produced. Alternatively, however, a hypochloraemic metabolic alkalosis may develop secondary to a high gastrointestinal
obstruction, due to loss of chloride in the vomitus. Appropriate fluid resuscitation will depend on the electrolyte/metabolic derangements that are present - hence the importance of being able to accurately identify these
What immediate life-threatening problems can be identified with a blood test in a vomiting patient?
An emergency database (EDB = MDB +Extended DB) should ideally be obtained in all cardiovascularly unstable animals that present with vomiting. The EDB should identify any immediate life-threatening problems such as hypoglycaemia, azotaemia
and electrolyte abnormalities
What type of fluids are usually indicated with vomiting?
Lactated ringer’s solution (LRS) is usually the
fluid of choice for most patients that are vomiting - metabolism of the lactate to bicarbonate helps in the correction of a metabolic acidosis. However, in the patient with an upper GI obstruction and consequent hypochloraemia, 0.9% saline is indicated. Whilst the RVN is not responsible for the choice of fluids, it is important to understand when each type could be used and any potential side effects they may
have.
What faecal analysis should be carried out on a patient with vomiting?
Faecal analysis can be useful in patients with diarrhoea. There are commercial test kits for detection of parvovirus antigen. It is important to note that whilst the majorityof patients who present with parvoviral enteritis will be unvaccinated and under 6 months old, it can be seen in older animals and should not be ruled out in a patient showing compatible clinical signs until testing has been carried out. In the case of a vaccinated animal showing clinical signs of parvovirus, a polymerase chain reaction (PCR) test may be needed to confirm the diagnosis. Whilst it will take longer to obtain a PCR result, prompt and aggressive intervention and treatment should be provided for the patient suspected of having parvoviral enteritis.
Microscopic examination of stained faecal smears may show large Gram-positive rods suggestive of Clostridia species or Gram-negative ones typical of Campylobacter species. Faecal examination for evidence of endoparasites can also be performed -
this may be an issue in particularly in young animals. Microbial culture and sensitivity tests may be performed.
What might haemotology show on a patient that is vomiting?
Haematology may show a leucocytosis and neutrophilia associated with infection but in animals with viral conditions there may be leucopaenia e.g. young animals with parvoviral enteritis. A blood smear can be performed to evaluate the need for
antibiotics in a patient with acute GI signs, such as vomiting and diarrhoea. Historically patients with acute haemorrhagic diarrhoea, for example, would receive empirical antibiotic treatment. However, as discussed by Hall (2018), in most acute onset cases
antibiotics are not indicated unless there is evidence of SIRS/sepsis (pyrexia,
increased WBC). Probiotics may be indicated in this situation.
What may biochemistry reveal in a vomiting patient?
Biochemistry may reveal pre-renal azotaemia in a hypovolaemic patient or those with severe dehydration; hypoglycaemia and hypoalbuminaemia may also be significant findings. In addition, it may help to identify other diseases (e.g. hyperglycaemia and
ketonaemia in diabetic ketoacidosis; increased ALKP and cholesterol in pancreatitis)
What can abdominal radiography help to determine?
Abdominal radiography can help to determine-
• the presence of foreign material e.g. intestinal or gastric foreign body
• the presence of a complete or partial obstruction e.g. ileus
• the presence of free abdominal gas or an effusion
• the size, shape, opacity and position of abdominal structures e.g. gastric dilation/volvulus
• the presence of an abdominal mass
Is diagnostic imaging always required in the vomiting patient?
Diagnostic imaging, including abdominal radiography and abdominal ultrasound, is usually essential in this situation. Whilst endoscopy can be performed in a vomiting patient for examination +/- biopsy, this is less likely in the emergency patient unless
for retrieval of an oesophageal/ gastric foreign body patient for examination +/- biopsy, this is less likely in the emergency patient unless for retrieval of an oesophageal/ gastric foreign body
What patient factors can contribute to loss of abdominal contrast?
Radiographic abdominal contrast is generally poor compared to other areas of the body. Many patient factors (e.g. thin, very young) and pathological conditions (e.g. abdominal fluid, emaciation) can be associated with further loss of abdominal contrast
Why is serial radiography sometimes indicated in the vomiting patient?
Sometimes, serial radiography and monitoring of gas patterns may be indicated. If the patient has
free abdominal gas (pneumoperitoneum), this indicates rupture of the GI tract or a penetrating abdominal wound- both would be considered a surgical emergency
How can abdominal ultrasound be a useful diagnostic aid in the vomiting patient?
Abdominal ultrasound is an extremely useful diagnostic aid especially in the acute abdominal presentation- prompt identification of any abdominal effusion is the initial aim. Even small volume effusions can be readily identified in most cases. A focussed assessment with sonography for trauma (FAST)/ point of care ultrasound examination (POCUS) should be performed (Powell, 2015). POCUS is invaluable in identifying the presence of free fluid within the abdomen- however it is also very useful for identifying ileus, a fluid filled stomach and other conditions present in the acute abdomen.
RVNs with suitable training can carry out POCUS examination and report the findings to the VS -this would not be termed as making a diagnosis in the same way that reporting an ECG abnormality would not be making a diagnosis.
What four areas are examined with a POCUS and what position should the patient be in?
POCUS technique
With the patient in left lateral recumbency, four areas are examined, in two planes:
• Subxiphoid (looking for fluid around the liver)
• Midline over the caudal abdomen/bladder
• Gravity dependent (left if patient in left lateral recumbency) flank
• Gravity independent (right if patient in left lateral recumbency) flank
Why is it important to repeat a POCUS or FAST scan an hour or two after fluid resuscitation?
It may be that no free fluid found on initial ultrasound examination in a hypovolaemic patient – however once the patient is fluid resuscitated it might start to gather. Therefore, for some patients, repeating the POCUS/ FAST scan, an hour or two after fluids have been started, is important in the identification of free
abdominal fluid
What should be done to avoid splenic injury in a patient that needs an abdominocentesis?
To avoid splenic injury, abdominocentesis is usually performed standing or in left lateral recumbency. However, in a patient with a large volume abdominal
effusion it may be more comfortable for the procedure to be carried out in sternal or standing position.
How do you perform an abdominocentesis?
• All the equipment should be gathered initially including plain tubes (biochemistry, culture and sensitivity), EDTA tubes (cytology) and microscope
slides for microscopy.
• To avoid splenic injury, abdominocentesis is usually performed standing or in left lateral recumbency. However, in a patient with a large volume abdominal
effusion it may be more comfortable for the procedure to be carried out in a sternal or standing position.
• Hair should be clipped over the area and the skin aseptically prepared.
• Either a single or a four quadrant abdominocentesis is performed. If a single insertion point is planned, this is usually slightly to the side and caudal to the
umbilicus, unless ultrasound examination has demonstrated fluid in a particular location. Four quadrant abdominocentesis splits the abdomen into four quadrants either side of the lineal alba (right cranial, left cranial, left caudal and right caudal). Abdominocentesis is performed in each of these locations.
• Using an aseptic technique, a 1 to 1.5-inch hypodermic needle is introduced into the abdomen, ideally under ultrasound guidance.
o Abdominocentesis can be performed using either an open or closed technique. Regardless of the method used, an aseptic technique is indicated due to the risk of introducing pathogens into the body cavity.
o The closed technique involves attachment of a syringe to the needle prior to insertion and fluid is collected by aspiration of the syringe. This
prevents air and bacteria from entering the abdomen. Air would lead to the appearance of pneumoperitoneum radiographically which might
cause diagnostic confusion. The disadvantage of this technique, however, is the potential occlusion of the needle bevel by omentum during suction.
o The open technique relies on passive gravitational flow of fluid from the abdomen, rather than syringe aspiration. It may be used more commonly in patients that have small volumes of effusion. There is, however, the inherent risk of air and bacteria being introduced- increasing the risk of infection, causing a pneumoperitoneum and potentially complicating any
subsequent radiographic interpretation. A needle or IV catheter is inserted, aseptically, in the most gravity-dependent portion of the abdomen and fluid allowed to flow by gravity.
What two techniques can abdominocentesis be performed?
Abdominocentesis can be performed using either an open or closed technique. Regardless of the method used, an aseptic technique is indicated due to the risk of introducing pathogens into the body cavity.
How is a closed abdominocentesis performed?
The closed technique involves attachment of a syringe to the needle prior to insertion and fluid is collected by aspiration of the syringe. This prevents air and bacteria from entering the abdomen. Air would lead to
the appearance of pneumoperitoneum radiographically which might cause diagnostic confusion. The disadvantage of this technique,
however, is the potential occlusion of the needle bevel by omentum during suction.
How is an open abdominocentesis performed?
The open technique relies on passive gravitational flow of fluid from the abdomen, rather than syringe aspiration. It may be used more commonly
in patients that have small volumes of effusion. There is, however, the inherent risk of air and bacteria being introduced- increasing the risk of
infection, causing a pneumoperitoneum and potentially complicating any subsequent radiographic interpretation. A needle or IV catheter is
inserted, aseptically, in the most gravity-dependent portion of the abdomen and fluid allowed to flow by gravity.
What is one of the most important aspects of analysing free peritoneal fluid?
one of the most important aspects of analysing free peritoneal fluid is to identify a patient that needs prompt surgical intervention
What type of testing should be performed on abdominal fluid?
Gross examination, cytology, haematology, total protein and biochemistry can all be performed
What important information can gross examination of abdominal fluid give you?
Gross examination of free peritoneal fluid can yield some important information- blood that does not clot suggests haemoabdomen; plant/food material in peritoneal fluid is indicative of rupture/ perforation of the GIT.
What are the potential causes of free peritoneal fluid?
The following are potential causes of free peritoneal fluid- septic peritonitis, non-septic peritonitis, haemoabdomen, uroabdomen, pancreatitis, bile
peritonitis, chylous effusion and neoplasia.
What cytological analysis is highly suggestive of septic peritonitis?
Cytological analysis is highly suggestive of septic peritonitis if there are–
➢ many leucocytes
➢ intracellular (phagocytosed) or extracellular bacteria
➢ toxic/degenerate changes in the neutrophils
the presence of toxic changes in neutrophils indicates an inflammatory response is taking place in the patient. When there is a sudden demand for increased numbers of neutrophils in the circulation, many of those that are developing in the bone marrow
are forced to mature more rapidly than normal. N.B. in this situation there are also likely to be increased numbers of band (immature) neutrophils seen. The toxic changes that might be present on a smear are not caused by bacterial damage but reflect unequal maturation of the nucleus and cytoplasm of the neutrophil.
What toxic changes can be seen in the cytological analysis where it is highly suggestive of septic peritonitis?
Toxic changes that can be seen include-
➢ blue granules/ foamy appearance of the cytoplasm
➢ swelling of the nucleus
➢ Dohle bodies (light blue-grey, oval, inclusions in the peripheral cytoplasm)
Based on composition what can free peritoneal fluid be classified as ?
Based on its composition, free peritoneal fluid can be classified as a transudate, modified transudate or exudates
What will the protein levels be in transudate, modified transudate and exudate in abdominal fluid?
Protein
Transudate
<25g/l
Modified transudate
>25g/l
Exudate
>30g/l
What will the levels of nucleated cells be in transudate, modified transudate and exudate in abdominal fluid?
Nucleated
cells
Transudate
<1 x 109/l
Modified transudate
<7x 109/l
Exudate
>7 x 109/l
What will the appearance be in transudate, modified transudate and exudate in abdominal fluid?
Appearance
Transudate
Clear, colourless
Modified transudate
Cloudy
Exudate
Thick, purulent, white, cream, yellow etc.
Describe transudate, modified transudate and exudate abdominal fluid?
Description
Transudate
low cellularity and a low protein content
Modified transudate
Intermediate between transudate and exudate.
Exudate
High cell count and high protein count
What are the different causes for transudate, modified transudate and exudate abdominal fluid?
Cause(s)
Transudate
Decreased plasma oncotic pressure/increased hydrostatic pressure e.g. congestive cardiac failure
Modified transudate
Decreased plasma oncotic pressure/ increased hydrostatic pressure; disruption to endothelium;
strangulation May be transition stage transudate and exudate as condition develops e.g. uroabdomen progressing to septic peritonitis
Exudate
Associated with an inflammatory process. May be associated with bacteria (septic) or sterile (non-septic)
What biochemical tests can be performed on peritoneal fluid?
It is also possible to measure the peritoneal fluid concentrations of glucose, lactate, potassium, creatinine, lipase, amylase, ammonia and bilirubin. It is not possible to give normal reference ranges for these in peritoneal fluid - the concentration will depend
on the underlying cause of the peritonitis (e.g. potential dilution effect).
What would a peritoneal glucose concentration lower than blood glucose indicate? Why would it be lower?
A peritoneal glucose concentration lower than blood glucose is likely in septic peritonitis as the bacteria present use glucose for energy
What would a peritoneal lactate concentration higher than blood lactate indicate?
A peritoneal lactate concentration higher than blood lactate is likely in septic peritonitis
How does peritoneal lactate and glucose compare to plasma as a diagnostic tool for septic peritonitis? What species might this be considered less accurate?
Peritoneal glucose level 1.1mmol/L lower than that obtained from a plasma sample; and peritoneal lactate level 2mmol/L greater than that obtained from a
plasma sample have been quoted as diagnostic for septic peritonitis in animals. However, assessment of lactate and glucose levels are considered less accurate in feline patients
What does a peritoneal potassium or creatinine concentration higher than blood concentration suggestive of?
A peritoneal potassium or creatinine concentration higher than blood concentrations is suggestive of uroperitoneum.
‘An abdominal fluid creatinine concentration to peripheral blood creatinine concentration ratio of > 2:1 was predictive of uroabdomen in dogs (specificity
100%, sensitivity 86%). An abdominal fluid potassium concentration to peripheral blood potassium concentration of > 1.4:1 is also predictive of
uroabdomen in dogs (specificity 100%, sensitivity 100%). All dogs with uroabdomen had an abdominal fluid creatinine concentration that was at least
4 times normal peripheral blood levels’
What would bilirubin in peritoneal fluid indicate?
Bilirubin is not normally present in peritoneal fluid – identification of bilirubin in peritoneal fluid would suggest damage to the gall bladder.
How do you perform a diagnostic peritoneal lavage?
Diagnostic peritoneal lavage (DPL)
If fluid is not located during abdominocentesis, in a patient with a history and clinical findings suggestive of free abdominal fluid, DPL may be performed. However, DPL is less likely to be required if ultrasound guided abdominocentesis can be performed.
DPL is like abdominocentesis but fluid is first introduced into the abdomen. It is left for a short time before being withdrawn and put into plain and EDTA tubes for cytological, biochemical and haematological analysis. Introducing fluid during DPL increases the chance of collecting free peritoneal fluid, especially if these is only a small volume present. Commercial DPL kits are available which use the Seldinger technique.
Alternatively, DPL can be performed using an over the needle cannula. Some advocate fenestrating the IV cannula to increase the chance of obtaining fluid; however, this would need to be performed carefully to ensure fragments of the catheter are not lost within the abdomen.
The urinary bladder is emptied and the ventral abdomen is aseptically prepared. Local anaesthetic may be administered prior to introducing a peritoneal dialysis catheter, or an over the needle 2 inch (5cm) 18-gauge cannula through the abdominal wall, 2cm
caudal to the umbilicus. 10-20ml/kg of warmed sterile saline (0.9 %) or lactated ringers is instilled into the abdominal cavity. The patient’s abdomen is massaged or the patient is gently rolled. The patient should be observed closely for any signs of discomfort or
respiratory distress. Increasing intra-abdominal pressure may worsen respiratory function, as well as cause significant discomfort to the patient. If the patient is already painful then analgesia should be given prior to carrying out the procedure. After a few minutes the fluid is withdrawn. In general, very little fluid is recovered but it is usually enough to allow a smear to be made to aid diagnosis.
What can amylase, lipase and cPLI levels in peritoneal fluid aid in the diagnosis of?
Amylase, lipase and cPLI levels in peritoneal fluid can be assayed and aid in the diagnosis of pancreatitis
When should diagnostic peritoneal lavage be avoided?
Diagnostic peritoneal lavage should not be performed if the patient has respiratory
distress - the fluid may put pressure on the diaphragm and cause further breathing
difficulties. DPL should also be avoided where there is major organ enlargement due
to the risk of puncturing the organ during the procedure. Mazzaferro (no date)
describes diagnostic peritoneal lavage.
What diagnostic tests can be run with diagnostic peritoneal lavage fluid?
If enough fluid is obtained, biochemical and haematological analysis can be performed
in addition to cytological analysis of a smear. This, however, would be qualitative rather than quantitative due to dilution effect i.e. creatinine might be present but the actual amount cannot be accurately quantified as it has been diluted.
Will a patient with with an acute abdomen generally have metabolic acidosis or alkalosis? What can be used to help treat this?
Generally, the patient will have a metabolic acidosis caused by hypoperfusion-induced hyperlactataemia and, often, loss of bicarbonate. The isotonic crystalloid solution, lactated ringers, is appropriate in this situation.
The patient may, however, have hypochloraemic metabolic alkalosis due to acute, prepyloric vomiting (i.e. stomach origin). In this situation, ringer’s solution or 0.9% NaCl may be preferred. 0.9 % NaCl will provide enough chloride to correct the metabolic alkalosis.
What can hypokalaemia arise secondary to in a patient with an acute abdomen? what treatment can be given to help correct this?
Hypokalaemia can arise secondary to increased potassium loss and decreased intake.
There are many causes of hypokalaemia, but it can be associated with both vomiting and diarrhoea, especially chronic diarrhoea. Clinical signs of hypokalaemia may not be apparent until the potassium levels are very low. If hypokalaemia is present, potassium supplementation is indicated. It is important to calculate the amount of potassium that is required to avoid over/under supplementation.
Potassium is added to the IV fluids, as outlined in the table. It is essential that the bag of fluids is appropriately identified to show that potassium has been added – the flow rate must not be altered significantly. Regular agitation of the bag is needed to ensure distribution of the potassium salts throughout the infusion. Ongoing assessment of potassium levels should be made every 4-6 hour (Odunayo, 2014). It should also be noted that in many patients, due to administering IV fluid therapy, potassium dilution can occur. Therefore, even if the potassium level is normal on presentation it may subsequently become depleted.
How much potassium should be added to fluids based on serum potassium levels?
Serum potassium Potassium chloride to be added
(mmol/litre fluids)
>5.5 Do not add
4.1-5.4 20
3.1-4 30
2.6-3 40
2-2.5 60
<2 80
What regular patient monitoring should be performed in a patient with electrolyte imbalances?
Regular patient monitoring should be performed especially of perfusion parameters.
Mucous membrane colour and CRT should be assessed. Central and peripheral pulses should be assessed for strength and quality. The heart should be auscultated at the same time enabling the identification of arrhythmias or a pulse deficit.
Blood pressure monitoring should ideally be performed. If available a multi-parameter monitor can be used. This means ECG and non-invasive blood pressure is monitored on a continued basis. While this can be invaluable in critically ill patients, ‘hands on’
monitoring remains vital where appropriate
Ideally what should a patients urine output be?
The patient should produce 1-2 ml/kg/hr.
How should urinary output be monitored in a patient receiving IV fluid therapy?
Urine output should also be monitored every 60 minutes to assess the effectiveness of IVFT. The patient should produce 1-2 ml/kg/hr. In patients that are dehydrated on presentation, urine output may be low initially. Ongoing monitoring can include assessment of fluid ‘ins and outs’, patient’s weight (which should increase as hydration improve), PCV and total solids assessment and serial POCUS assessment of the
bladder size.
What do blood lactate levels help to assess the efficacy of?
Blood lactate levels should be monitored, where possible, throughout treatment to
assess the efficacy of perfusion
What are the normal levels for plasma lactate?
Normal levels for plasma lactate are <2.5mmol/L.
What treatment is involved in acute gastrointestinal presentations?
In many acute presentations, treatment is usually symptomatic – symptomatic
treatment is likely to involve case-specific combinations of intravenous fluid therapy,
analgesia, gastrointestinal drug therapy and dietary management.
When is intravenous fluid therapy indicated in patients with acute gastrointestinal signs - what type of fluids may be used and when?
IVFT- Crystalloid fluids (usually isotonic) are indicated in a patient with hypovolemia +/- dehydration associated with vomiting/diarrhoea. Relatively low volumes of hypertonic saline (HTS) can be administered to a patient needing rapid, fluid
resuscitation e.g. GDV patient. Synthetic colloids may be considered if the patient is hypoalbuminaemic e.g. sepsis. However, as previously outlined, there is debate over the use of synthetic colloids in companion animals. A large volume of fresh frozen plasma (FFP) would be needed to significantly increase plasma albumin levels in a patient with hypoalbuminaemia - making this an uneconomical and impractical option.
FFP would, however, be appropriate if the patient had a coagulopathy
What type of analgesia protocol is usually required with abdominal pain?
Multimodal analgesia is most likely to be effective in a patient with abdominal pain.
What types of analgesia can be used with abdominal pain?
Full mu agonist opioids (e.g. morphine/ methadone) are likely to be required for a patient with abdominal pain. Fentanyl could be administered as a constant
rate infusion (CRI). In a mild case, a partial agonist (e.g. buprenorphine) may be administered instead but it is essential that the patient’s level of pain is
assessed very carefully. If in doubt it should be assumed that the patient is experiencing a high level of pain. However, Bradbrook (2016) advocates the
use of buprenorphine in a cat with abdominal pain as full mu agonists can cause excess sedation.
➢ Lidocaine has anti-inflammatory effects and can be used alone or in combination with other drugs as a CRI (e.g. morphine, lidocaine and ketamine) to decrease the amount and frequency of full mu agonist administration. N.B. full mu agonist opioids can cause nausea. However, lidocaine can also cause nausea and is cardiotoxic if overdosed.
➢ Other local anaesthetic techniques may be employed e.g. epidural.
➢ Ketamine could be administered as a CRI alone with an opioid (morphine) +/-
lidocaine to provide multimodal analgesia.
➢ Whilst non-steroidal anti-inflammatory agents have very good anti-inflammatory and moderate analgesic properties, they are not suitable in a hypovolaemic/
hypotensive patient or when gastric ulceration is suspected.
➢ In some situations, paracetamol may be used alongside other analgesia in a dog (not a cat)
➢ Gabapentin may be used for adjunctive analgesia in a cat. It is known to provide visceral analgesia for people although there is currently no evidence of this in cats
What drugs are considered full mu opioids?
Full mu agonist opioids (e.g. morphine/ methadone) are likely to be required for a patient with abdominal pain. Fentanyl could be administered as a constant rate infusion (CRI).
What effects does lidocaine have and what other drugs can it be used in combination with?
Lidocaine has anti-inflammatory effects and can be used alone or in combination with other drugs as a CRI (e.g. morphine, lidocaine and ketamine) to decrease the amount and frequency of full mu agonist administration.
What drug groups might be considered in a patient with gastrointestinal signs?
Depending on the patient’s status and the actual/ potential diagnosis, symptomatic gastrointestinal drug therapy may include some of the following - o antiemetics o antinausea agents o antispasmodics o gastrointestinal protectants/ anti-diarrhoeals o antacids o histamine (H2) antagonists o proton pump inhibitors (PPIs) o prostaglandin E1 analogue
What effect does maropitant have?
Maropitant blocks receptors in the vomiting centre in the medulla and can be used as an antiemetic and antinausea agent. It modulates the inflammatory response and may provide some visceral analgesia
What effect does metoclopramide have?
Metoclopramide is an antiemetic with upper GI prokinetic activity which may be used in dogs and cats. it stimulates peristalsis and works centrally and peripherally to decrease vomiting.
N.B. Generally, it is advised that an antiemetic is only administered once a surgical cause of vomiting e.g. foreign body has been ruled out.
What effect does sucralfate have?
Sucralfate is a gastro-intestinal protectant which combines with exudates in the upper GI tract and creates a barrier over areas of mucosal damage e.g. gastric ulcers
What effect does kaolin have?
Kaolin is an adsorbent antidiarrhoeal agent.
What effect does antacids have?
Antacids (combination of aluminium hydroxide, calcium carbonate and magnesium hydroxide) decrease pepsin activity and stimulate local prostaglandin synthesis.
