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Tag: Pain Management

  • Focus on GDV, part 4: the recovery

    Focus on GDV, part 4: the recovery

    Postoperatively, gastric dilatation-volvulus (GDV) patients remain in our intensive care unit for at least two to three days.

    Monitoring includes standard general physical examination parameters, invasive arterial blood pressures, ECG, urine output via urinary catheter and pain scoring.

    I repeat PCV/total protein, lactate, blood gas and activated clotting times (ACT) immediately postoperatively and then every 8-12 hours, depending on abnormalities and patient progress.

    GDV recovery
    Patient recovering in the pet intensive care unit. As well as standard monitoring parameters, GDV patients have constant ECG, arterial blood pressure and urine output monitoring to enable the early detection and correction of abnormalities.

    I always repeat these blood tests postoperatively, as IV fluids given during the resuscitation and intraoperative period often cause derangements. I use the results to guide my fluid therapy, but also take it with a grain of salt.

    IV fluids

    I generally continue a balanced and buffered crystalloid. The rate depends on blood pressures, urine output and assessment of general physical examination parameters for perfusion and hydration, but I try to avoid fluid overload and reduce the IV fluids postoperatively as soon as possible.

    Coagulopathy

    Prolonged clotting times are frequently seen as a result of consumption in a dog with GDV. However, one should note it can also occur as the result of haemodilution.

    As the underlying disease process has been corrected, and haemostasis achieved during surgery, I usually monitor ACTs, but may not necessarily treat with blood products as prolonged ACTs do not always translate to clinical bleeding. Unless clinical evidence of bleeding exists, I generally hold off treatment and monitor.

    Hypoproteinaemia

    Low total protein is also common. This is generally due to haemodilution from fluid resuscitation. However, a low total protein does not mean oedema will develop, or that it requires management. I generally track the protein levels, use conservative fluid therapy and try to correct it by instituting enteral nutrition as soon as possible.

    Electrolyte imbalances

    Hypokalaemia is a common complication of fluid therapy. This can be rectified with potassium supplementation in the IV fluids.

    Hyperlactataemia

    If present post-surgery, this is usually corrected with a fluid bolus. However, I always assess for other things that may affect oxygen delivery to the tissues, such as poor cardiac output (arrthymias), hypoxaemia (respiratory disease) and anaemia (from surgical blood loss).

    Arrhythmias

    Ventricular arrhythmias are common post-surgery. Accelerated idioventricular rhythms are the most common cause, especially if a splenectomy was performed.

    arrhythmia
    Ventricular premature contractions are common postoperative arrhythmia.

    Before reaching for anti-arrythmia medications, first check and correct:

    • electrolyte abnormalities
    • hypoxaemia
    • pain control
    • hypovolaemia or hypotension

    If they are still present, despite correction of the above, consider treating the rhythm if:

    • multifocal beats (ventricular premature contractions of various sizes)
    • overall rate greater than 190 beats per minute
    • R-on-T phenomenon
    • low blood pressure during a run of ventricular premature contractions

    I start with a bolus 2mg/kg lidocaine IV and start a constant-rate infusion of 50ug/kg/min to 75ug/kg/min.

    Anaemia

    It is common to have a mild anaemia post-surgery, due to a combination of blood loss and haemodilution. In the absence of transfusion triggers – such as increased heart rate, increased respiratory rate or hyperlactataemia – it does not require treatment.

    Vomiting

    Anti-emetics are the first line of medication. Non-prokinetic anti-emetics, such as maropitant and ondansetron, can be used immediately; otherwise, after 12 hours, metoclopramide can also be used postoperatively. If the patient remains nauseous despite these medications, the placement of a nasogastric tube can ease nausea by removing static gastric fluid.

    Excessive pain relief may also contribute to the nauseous state.

    Pain relief

    I mostly rely on potent-pure opioid agonists, such as fentanyl constant-rate infusions and patches. This is generally sufficient for most patients. Ketamine is occasionally used.

    • Some drugs listed in this article are used under the cascade.
  • Focus on GDV, part 3: surgery tips

    Focus on GDV, part 3: surgery tips

    Following on closely from the first two parts of our February focus on gastric dilatation-volvulus (GDV) – which covered IV fluid resuscitation, pain relief and gastric decompression – we turn to surgery.

    Here, I offer a few tips to help ensure the procedure runs as smoothly as possible.

    Abdominal incision

    Make the abdominal incision large – from the xipoid to the pubis. You cannot perform a proper exploratory laparotomy without proper visualisation. Additionally, when it comes time to re-rotate the spleen, you will need all the space you can get. Removal the falciform fat to help improve exposure.

    Derotation

    derotation
    Figure 1. Derotation of the stomach. Standing on the right side of the patient, one hand pulls as the other pushes.

    The degree of rotation is variable from 90° to 360°, so not all GDV surgeries will be the same. If the omentum is draped over the stomach, this is pathognomonic for GDV.

    When derotating, stand on the right side of the patient as all descriptions are based with the surgeon on that side.

    During volvulus, the pylorus rotates ventrally then to across to the left side of the body.

    Method

    With one hand (usually your right) reach down the left abdominal wall and firmly grab the stomach down where the spleen normally resides, then pull towards you (Figure 1). At the same time, use your other hand to apply downward pressure (or pressure in the dorsal direction) on the right side of the stomach. This simultaneous pulling on the left side of the stomach and push on the right side of the stomach is generally successful.

    At this stage, it is important to check things have gone back to their normal places. Ensure the:

    • pylorus is to the right and you are able to track it through to the duodenum and pancreas
    • fundus is to the left
    • omentum is hanging off the caudal aspect of the stomach
    • spleen is also derotated

    Passing a stomach tube can sometimes help you identify the oesophagus – you can feel it running along the inside of the gastric cardia and fundus.

    Further decompression

    If the stomach is still distended and hard to manipulate, reducing the size of the stomach can make derotation significantly easier. Pass the stomach tube again or aspirate more gas from the stomach using a 18G needle, extension set, 50ml syringe and three-way tap.

    Assessment of the stomach

    incision
    Figure 2. Incision into the pyloric region of the stomach.
    Figure 3. Completed incision gastropexy.
    Figure 3. Completed incisional gastropexy.

    Gastric necrosis is most likely to occur along the greater curvature of the body and fundus. Lifting up the stomach and looking at the dorsal aspect of these areas is important. Allow 5 to 10 minutes after derotation before resecting the affected areas to see if it regains colour and pulsations.

    Pexy

    I personally perform incisional gastropexy – I find them easier and very effective. I find an area on the pyloric region of the stomach where minimal tension exists, when brought to the lateral body wall (Figures 2 and 3).

    Ensure you do not accidentally incise into the diaphragm; the muscle fibres of the diaphragm radiate out and insert at the costal arch. Identify the transverse abdominal muscles and pexy the stomach to here.

    I also ensure muscularis to abdominal muscle contact to increase the strength of the pexy once it is healed.

    Spleen

    The spleen is almost always engorged in GDV cases, but this does not necessarily mean it needs to be removed.

    Always assess the splenic blood supply as it is not uncommon for splenic vessels to tear or thrombose during the volvulus.

    If there is any concern that the splenic arterial flow is compromised, I would perform a splenectomy.

    Stomach still dilated after pexy?

    What if the stomach appears to be still dilated? Generally, once the stomach is derotated, normal anatomy has been achieved and the pexy is performed, the remaining food and gas will pass with time. You can try to empty more via a stomach tube or aspiration with a large needle, but this is not generally required. I would not perform a gastrotomy to remove contents.

    Next week, we will cover common postoperative complications.

    >>> Read Focus on GDV, part 4: the recovery

  • Focus on GDV, part 2: releasing the pressure

    Focus on GDV, part 2: releasing the pressure

    Last week we covered IV fluid resuscitation and pain relief. This week we will go into more detail about gastric decompression.

    stomach tube
    Passing the stomach tube inside the roll down into the oesophagus (click to zoom).

    Gastric decompression can be achieved in two ways:

    1. trocarisation
    2. stomach tube (orogastric tube) placement

    The decision on which method to use depends on many factors – personal preferences, past experiences and clinical protocols, to name a few.

    So, which one is best? A retrospective analysis of 116 gastric dilatation-volvulus (GDV) patients (Goodrich et al, 2013) found both methods of gastric decompression had low complication and high success rates, and either technique is acceptable.

    If one method fails to achieve gastric decompression, the other can be tried.

    How to decide

    Personally, I use either or sometimes both. Which one I choose first depends on the situation. My decision-making process goes something like this:

    Not clinically obvious or mild GDV

    These are often diagnosed based on supportive radiographic findings as history and presenting clinical signs making me suspicious of a GDV.

    I would always try to pass a stomach tube in these patients first, as the tube is passes easier when the gastric distention is milder. Although this procedure generally requires prior opioid analgesia administration to help reduce the stress, it can achieve rapid and lasting decompression of the stomach.

    I often leave the tube in throughout stabilisation, just prior to induction of anaesthesia for surgical correction of the torsion. The tube allows continual release of gastric gases that can accumulate again rapidly if the tube is removed prior to surgery.

    Obvious or severe GDV

    The abdomen in these animals is often distended and tympanic. I will perform trocarisation in these cases first, as passing a stomach tube in these patients is often unsuccessful. It allows rapid gastric decompression, which is particularly important in cases with evidence of respiratory compromise.

    After the trocar is no longer releasing gas, I will then pass a stomach tube. At this stage, it is often easier to pass the stomach tube once the gastric pressure has been reduced. Once again, I often leave the tube in during stabilisation.

    How to perform

    Stomach tube

    • The main risk is rupture of the oesophagus or gastric wall.
    • Pre-measure and mark the tube from the mouth to the level of the last rib.
    • Use a roll of adhesive bandaging material as the mouth gag. I prefer to use Elastoplast as it has an incompressible plastic core and the diameter is just large enough to fit our largest diameter stomach tube.
    • Unwrap approximately 30cm of Elastoplast before placing the roll of tape inside the mouth.
    • Wrap the tape snugly around the muzzle to prevent the dog from opening its mouth and dislodging the roll.
    • Lubricate the tube to reduce frictional trauma to the oesophagus.
    • Pass the stomach tube through the core of roll and into the mouth. You will feel a dead end at the level of the lower oesophageal sphincter, where the volvulus has torsed the oesophagus.
    • Apply gentle constant pressure and, most times, the tube will pass through into the stomach. Sometimes a puff of gas can be heard and felt from the aboral end of the tube when it enters the stomach. The tube can also be palpated when the stomach is decompressed.
    • The tube is taped to the muzzle to prevent dislodgement and the aboral end placed in a bucket to allow fluid to exit via gravity and siphon.
    • If it does not pass, reassess to see if trocarisation is required to relieve some pressure in the stomach

    As mentioned above, I generally leave the stomach tube in while continuing to stabilise the patient and prepare for surgery. Gas can rapidly accumulate in the stomach and cause rapid deterioration if the tube is not left in. The tube is removed just prior to induction of anaesthesia.

    tape
    Placing a roll in the mouth to prevent biting down on the stomach tube.

    Trocarisation

    • The main risk is hitting the spleen while trying trocarisation. To avoid this, identify the most tympanic site by palpation, or use the ultrasound to confirm the absence of the spleen.
    • A 3in, 14g catheter is usually sufficient.
    • Clip and surgically prep a 10cm by 10cm area where you intend to place the catheter.
    • Insert the catheter to the hub and remove the stylet.
    • Although local anaesthetic in the area is ideal, you will not have time to do this in most cases – especially the very unstable ones. Also, since I administer pure opioid agonist intravenously to most confirmed GDV cases on presentation, local anaesthetic is not required.
    • Remove the stylet and gas should come blowing out under pressure.
    • Once the gas flow starts to slow down, gently apply inward pressure or pressure on the dilated stomach, which helps ensure the stylet does not fall out of the stomach and as much of the gas is removed as possible.

    >>> Read Focus on GDV, part 3: surgery tips

  • Focus on GDV, part 1: resuscitation

    Focus on GDV, part 1: resuscitation

    Last month we covered a bit of pathophysiology, presenting pathophysiology, presenting clinical signs and the radiographic diagnosis of gastric dilatation-volvulus (GDV).

    Now we cover the three things you need to do as soon as a suspected case is presented:

    1. IV fluid resuscitation
    2. decompression of the stomach
    3. pain relief

    Depending on the number of staff you have, all of these can be performed simultaneously. If not, follow the above order as shock is the most imminent problem.

    Catheter placement

    Fluid resuscitation is relatively straightforward. Most GDV patients will be in some degree of shock, varying from mild to severe. Regardless of the actual degree, all patients will require IV fluids.

    The placement of IV catheters is particularly important; their numbers and diameter will influence the rate of response to treatment. Large-bore catheters allow faster flow of fluids compared to smaller ones, while multiple catheters allow concurrent delivery of two bags of fluids as opposed to one – particularly important in large dogs. Therefore, always try to place the largest catheter possible (for example, 18G or larger for large-breed dogs) into the cephalic veins.

    Once the catheters have been placed, collect 2ml to 3ml of blood for baseline measurements. These can be collected directly from the catheters and should include:

    • PCV/total protein
    • blood gas analysis
    • lactate
    • activated clotting time
    • electrolytes
    • later, full haematological and biochemical analysis

    Once the baseline bloods have been collected, fluid resuscitation should start immediately.

    How much, how fast?

    fluid
    Fluid resuscitation is relatively straightforward, says vet Gerardo Poli.

    How much fluid should you deliver, and how fast? My “go to” fluid is crystalloids and I generally start with a 20ml/kg bolus of an alkalinising crystalloid.

    I perform bolus therapy, so 10ml/kg to 20ml/kg fluid doses rather than shock rates 90ml/kg/hr, as I feel it allows me to better titrate my fluid therapy to effect. It also helps minimise excessive fluid administration and the problems with haemodilution – such as anaemia, hypoproteinaemia and prolonged coagulation times.

    As fluids are being delivered, I administer pain relief and start gastric decompression (covered next week).

    The decision to administer more fluids depends on whether I have achieved some end point resuscitation variables, such as:

    • a reduction in heart rate
    • a reduction in capillary refill time
    • an improvement of mucus membrane colour
    • improvement in pulse pressures

    Improvement in mentation is not often reliable as the sedative effect of analgesia, which I generally give during fluid resuscitation, often confounds this effect.

    Shock therapy

    If evidence of shock still exists, despite the initial fluid boluses and gastric decompression, I will consider more fluids. This can include hypertonic saline or colloids.

    In my experience, a repeat of a smaller dose of crystalloid fluid bolus is often adequate (10ml/kg). The transition on to hypertonic saline (7% solution) or colloids is influenced by the results of the aforementioned baseline diagnostics.

    A reduction in PCV/total protein suggests blood loss. In this case, I will consider either hypertonic saline (3ml/kg to 5ml/kg of 7% solution), a dose of colloids or even blood products, such as whole blood or packed red blood cells.

    If significant prolongation in activated clotting time occurs, likely from consumption, then I may incorporate fresh frozen plasma into my fluid therapy. This is in anticipation of possible surgery, where prolonged coagulation times can not only be troublesome, but life-threatening.

    Lactate

    A quick note on lactate – I don’t use the baseline reading as a prognostic indicator or an indicator of gastric necrosis. This is supported by recent findings claiming it is not the level of lactate that is predictive, but the degree of improvement in response to fluid resuscitation and gastric decompression.

    I have seen unreadable lactate levels – greater than 15mmol/L – in patients who returned to reasonably normal levels within an hour of stabilising. These patients also went on to survive surgery.

    Pain relief

    After starting IV fluid resuscitation, I generally administer pain relief while the team is preparing for gastric decompression. To keep things simple, I stick to an easily accessible pure opioid agonist at 0.2mg/kg IV. I avoid subcutaneous or even intramuscular administration as the patient is often in shock; the peripheral blood is shunted centrally to the heart and the brain and absorption can be variable.

    I find this offers a reliable and great degree of pain relief that helps reduce anxiety levels and, consequently, reduces oxygen demand. It has minimal cardiovascular effects and the mild sedative effect also helps with the process of decompression.

    >>> Read Focus on GDV, part 2: Releasing the pressure (gastric decompression)

  • Christmas dangers

    Christmas dangers

    Christmas can be a busy time for vet clinics, so here is a list of common intoxications and conditions to keep an eye out on during the festive period.

    Chocolate

    • Michael Pettigrew / fotoliaNumerous online calculators can determine whether a toxic dose has been consumed and they are a great place to start.
    • I always perform emesis in patients that have ingested chocolate, even hours after ingestion as often large amounts can reside in the stomach.
    • Remember that cardiac arrhythmias can also occur in clinically normal looking patients, so perform an ECG.
    • The toxic components can be reabsorbed through the bladder wall; therefore, urinary catheterisation is a part of management of this intoxication.

    Onions

    • Onions used in roasts and on BBQ’s can cause Heinz body formation, haemolytic anaemias and pigmenturia.
    • This is not a common intoxication, but should be considered in anaemia patients and those with discoloured urine.

    Raisins

    • Commonly used in Christmas cakes and puddings. They can cause acute kidney failure, the exact mechanism of action is unknown, and there does not appear to be a dose-dependent relationship.
    • It should always be a differential for azotemic patients this time of year.
    • IV fluid induced diuresis for 48 hours is the safest way to manage raisin exposure.

    Mistletoe

    • The berries can be fatal, even if only a couple are ingested.

    Ethylene glycol

    • In colder climates, ethylene glycol can be a very common toxicity.
    • This sweet liquid is very attractive to pets and can cause acute renal failure, with the first signs being acute onset ataxia.

    Macadamia nuts

    • Macadamia nuts are common in some parts of the world. They result in joint pain in the hocks and carpus leading to weakness and ataxia.
    • Often confused with trauma and soft tissue injuries. Hyperextension of the hocks and sometimes flexion of the carpus are the clinical features.

    Xylitol

    • Xylitol is a sugar-free product used in lollies and baking.
    • In dogs, it triggers endogenous insulin to be released and a subsequent hypoglycemia develops. It can also cause hepatic failure.
    • As a general rule, I approach all intoxications as if they could be fatal as it is rare to know exactly how much of the toxic agent they have been exposed to. I consider if a patient I am treating for intoxication never develops clinical signs and wonder whether it was going to or not is the best outcome.

    Strings

    • Look under the tongue.
    • Linear foreign bodies can be difficult to diagnose. Some features on abdominal radiographs to look out for include abnormal bunching of the small intestines, and “c” and “comma” shaped gas patterns.

    Christmas meals

    • Gastroenteritis is the most common presenting condition over the Christmas period, with dietary change and indiscretion often being the culprit.
    • Bones can lead to obstructions from oral cavity to the intestines and can also cause constipation.
    • Leftover meat trimmings, often fat laden, are a common cause of pancreatitis.

    BBQ skewers

    • In some parts of the world (Australia especially) BBQs are common around Christmas time.
    • BBQ skewers can cause gastrointestinal tract perforation and septic peritonitis.
    • Because they are not radiopaque they are often difficult to diagnose.
  • Abdominal radiography, part 2

    Abdominal radiography, part 2

    Last week’s tips (Abdominal radiography, part 1) were about taking appropriate images.

    Now, here are some tips on interpreting those images.

    Interpretation

    abdominal x-ray
    Abdominal x-ray (click to zoom).

    I often find there is too much to look at and it gets confusing with overlapping organs. I like to step back and look from a distance; sometimes, this gives me an overview of the image first.

    Next, I use a systematic approach, starting with extra-abdominal structures and working inwards.

    Then I assess the main organs – liver, spleen, kidneys, bladder and prostatic region – and assess for a uterus. Once I have identified and assessed those, I look at the gastrointestinal tract (GIT).

    What part of the GIT is it?

    This can be the most confusing part. I start with the stomach, assess size and position, then identify and track the colon from caecum to rectum. Once I’m happy I have identified the stomach and colon then everything else with gas in it is likely to be small intestinal.

    Enema and a walk

    If there is too much faeces, or if the gas is colonic, I administer a suppository enema to facilitate defecation. This can dramatically clear up a confusing x-ray and move gas.

    Repeat the study

    If I am still concerned about an obstruction, but it is not obvious, I either transition to an ultrasound or repeat the abdominal study after a couple of hours of IV fluids and pain relief.

    I find, once a patient is rehydrated, the GIT starts to move; gas and faeces shift and things can look surprisingly different in a couple of hours. If it remains the same, or worsens, that also provides valuable information.

    Consider high GIT and partial obstructions

    Don’t forget pyloric, high duodenal and partial obstructions that don’t give you the classic small intestinal dilation. The absence of a radiopaque foreign body or gas dilated small intestines do not rule out an obstruction.

  • Temporary catheters in obstructed FLUTDs: buying time with a blocked cat

    Temporary catheters in obstructed FLUTDs: buying time with a blocked cat

    Obstructive feline lower urinary tract disease (FLUTD) is a common presentation in both general practice and emergency settings.

    Every clinician has his or her own approach to treating and managing a cat with obstructive FLUTD signs. Working in an emergency setting, once I have confirmed an obstructed bladder via palpation, I focus on trying to relieve the obstruction as quickly as possible.

    The first step is obtaining consent from the client to administer pain relief (an opioid IV or IM), place an IV catheter, collect blood for biochemistry, electrolyte and blood gas analysis, and temporarily relieve the obstruction.

    At our hospital, we achieve temporary relief of the obstruction generally within 15 minutes of patient arrival.

    Process

    blocked cat
    Obstructive feline lower urinary tract disease is a common presentation in general practice.

    We do this in three steps:

    1. Assess the tip of the penis, occasionally a crystal/mucus plug is all that is blocking the penis.
    2. If this is not the case, I pass a pre-lubricated 22g IV catheter tip (without the stylet) into the penis with a 10ml syringe, containing 0.9% NaCl, connected for hydropropulsion. In the vast majority of cases, this helps to dislodge the urethral blockage enough to enable some urine to pass (urination suggests active urination by the cat).
    3. Once urine is flowing, I pass a 12cm or 14cm rigid catheter, tape it to the tail and leave it in place to allow constant drainage.

    If the 22g IV catheter does not relieve the obstruction, I would use a rigid catheter and progressively advance it up the urethra while hydropropulsing with the saline the entire time. Once unblocked, then I will tape it to the tail as aforementioned.

    Quick Tip: Once you have the catheter in the tip of the penis, pull the prepuce straight out to straighten the penis and thus the penile urethra. Otherwise, the bend in the penile urethra may hinder the passage of the catheter.

    Benefits

    The benefits I see of placing a temporary urinary catheter include:

    • immediate relief to the patient and reduces their stress levels
    • provides a sample for urinalysis
    • allows you time to run through the diagnostic and treatment plan in more detail with clients
    • buys you time to stabilise the patient for their anaesthetic later to place a closed system indwelling urinary catheter and then bladder lavage

    Quite often, your patient would present unwell enough that you should have no issues (resistance to) passing this temporary urinary catheter, provided you have given pain relief on presentation.

    In fractious patients, I usually forgo the temporary catheter and focus on stabilising the patient. The aim is to have them stable as soon as possible for sedation or a general anaesthesia to place a longer indwelling urinary catheter.

  • Cat bite abscesses

    Cat bite abscesses

    Cat bite abscesses are one of the most common presentations in general practice.

    Even in an emergency setting, I see a number of these patients. Usually they are obvious, but, occasionally, they’re not so obvious and the patient comes in lethargic, inappetant and often “painful”.

    Overly dramatic?

    One thing I’ve learned in my time is a cat bite abscess should be considered for all cats that have pyrexia. For a pyrexic outdoor cat without an obvious cause, I include a whole body clip as part of my diagnostic process. This is because a cat bite can start as a cellulitis and bite wounds are very small.

    Whole body clipping may sound dramatic, but it has saved me many times and helped rule out cat bites as a major differential for cats with pyrexia.

    Standard approach

    Everybody treats cat bite abscesses in their own way, but here’s my approach:

    • Any warm, painful area or swelling should be clipped to look for bite wounds.
    • I always look for all four tooth marks – you can miss wounds and other developing abscesses by focusing only on the obvious bite wounds.
    • You must establish drainage, surgically explore and lavage. This means patients are always placed under heavy sedation or a full anaesthetic. Why do I always recommend this? I have found cat nails, hair and teeth in abscesses before; without removing those foreign bodies, the abscess won’t heal and antibiotics won’t be effective.
    • I almost always administer antibiotics, even if I have removed an abscess en bloc and no contamination exists.
    • Pain relief is always indicated, depending on the age and stability of the patient. An NSAID is my preference, but only after I have corrected my patient’s fluid deficits, otherwise I select a different type of analgesic.
    • Drains? Sometimes I place drains in very large abscesses, but mostly I prefer to close primarily after appropriate debridement.
  • Making sense of effusions (part 1): is your patient septic?

    Making sense of effusions (part 1): is your patient septic?

    Interpreting effusion samples can be confusing, so try to think of effusions as if you were collecting a blood sample.

    Septic effusion
    Septic effusion.

    Many of the in-clinic diagnostic tests that apply to blood samples also apply to effusions, such as:

    • PCV/total protein
    • smears
    • glucose
    • lactate
    • potassium
    • creatinine
    • bilirubin

    It’s not enough to only check the protein concentration of the effusion then classify it as either a transudate, modified transudate or exudate and leave it at that – there is more information left to extract from that sample.

    Challenging diagnosis

    Determining if an effusion is septic can be a challenge. Here are the steps I take.

    analysis
    Abdominal and peripheral blood gas analysis.
    1. Perform a cytological examination of your effusion in the smear and look for inflammatory cells and the presence of bacteria. Look inside the cells as well as outside. If you don’t see bacteria it does not mean it isn’t a septic effusion, and only a couple bacteria are needed for me to call it septic.
    2. Glucose and lactate: You need to compare the glucose levels in the effusion with blood glucose levels. If the effusion glucose level is less than serum glucose, it is more likely you have a septic exudate. This makes sense in that bacteria would metabolise glucose in the effusion, leading to lower glucose levels. A by-product of metabolism is, of course, lactate. Therefore, you next need to check the lactate levels in the effusion and compare it to the serum lactate level. If lactate level in the effusion is more than the serum lactate level, then again you have more evidence you are dealing with a septic exudate.

    Try to measure glucose and lactate from both blood and effusion samples at the same time on the same machine. Keep in mind glucose and lactate values are less accurate for monitoring for the presence of bacteria in post-surgical patients.

  • Isoflurane and oxygen: the dangers of 2 and 2

    Isoflurane and oxygen: the dangers of 2 and 2

    It is a common practice to place all patients on 2% isoflurane and 2l/min oxygen flow rate, but blanket isoflurane saturations and oxygen flow rates can be dangerous.

    2 and 2
    Take time to consider your anaesthetic approach.

    Without a doubt, the majority of patients seem to do just fine at these levels; but every patient is different, and simply placing all patients on 2% isoflurane and 2l/min oxygen may be introducing an easily avoidable risk into anaesthesias.

    Isoflurane

    Isoflurane can cause severe effects such as hypotension and respiratory depression, so 2% isoflurane may be too high – especially for patients that are critically ill or have been premedicated with sedatives/anxiolytics.

    In these patients, the isoflurane can be safely titrated down while monitoring the patient’s reflexes and vitals. Consider administering IV pain relief instead of turning up the isoflurane levels if the patients are too “light” and responding to pain. Examples include a low dose pure-opioid.

    It is important to titrate its use like any other anaesthetic agent, maintaining an appropriate level of anaesthesia while minimising potential side effects.

    Oxygen

    It is common to use a standard 2l/min oxygen flow for all anaesthetics regardless of the type circuit, but this will not meet the oxygen requirements for larger patients. It is best practice to work out the appropriate flow rate amount using an oxygen consumption chart.

    I cannot stress enough the importance of taking the time to consider your anaesthetic approach in patients, especially compromised ones such as those with renal/hepatic disease or circulatory deficits.

    Titrating anaesthetic agent levels can increase the stability of your patient under anaesthesia and significantly reduce the life-threatening complications.