Case report on surgical management of a pericardial effusion and subsequent pericardectomy

A7-year-old, female, neutered Labrador Retriever presented as an emergency with a pericardial effusion which was consequently drained. A computerised tomography (CT) scan and echocardiograph provided evidence of an irregular mass located between the right atrium and pericardium, which was suspicious of a haemangiosarcoma. The patient was discharged with the owners being fully informed of the possible outcomes and further treatment methods or care the patient could receive. However a second pericardial effusion subsequently developed and the patient was admitted into the intensive care unit (ICU).

History

The patient was presented to a veterinary surgeon (VS) on observation of respiratory changes by the owner. Clinical signs at this stage included tachypnoea, tachycardia and a pot-bellied abdomen. The diagnosis of a pericardial effusion was confirmed on ultrasound and an emergency referral was obtained. On arrival the patient was triaged and admitted to the ICU. Oxygen saturation (SpO₂) was monitored using a pulse oximeter. Oxygen therapy was provided via flow by, but no medication was given at this point.

Case description

On admission vital parameters were assessed including: heart rate, pulse rate and quality, respiratory rate and temperature (values are listed in Table 1). A full auscultation of the thorax was completed and muffled heart sounds were identified. Diagnosis of a pericardial effusion was confirmed with a thoracic ultrasound. An intravenous (IV) catheter was placed in the left cephalic vein according to practice policy. SpO₂ and an electrocardiograph (ECG) were monitored via a multi-parameter monitor. An ultrasound guided pericardiocentesis was performed with 224 ml straw coloured fluid being drained from the pericardium. Cytology of this fluid showed high evidence of nucleated cells and mixed cell inflammation. An echocardiograph showed no evidence of the suspected mass in the pericardium, however a CT scan did reveal a small pleural effusion. Due to the recurrence of the pericardial effusion the VS opted for a pericardectomy as the method of treatment.

Preoperatively the patient's vital parameters were monitored by the nurse. This is important as changes in these parameters may indicate a pericardial effusion has re-occurred or the occurrence of a haemorrhage resulting from the pericardiocentesis. A general assessment of the patient was also completed at least three times daily to evaluate the patient's behaviour, appetite and pain level. The patient's nutritional requirements and consumption was also observed and recorded. The patency of the IV catheter was checked twice a day by flushing with saline. A patent IV is important for the induction of anaesthesia and preventing the side effects associated with perivascular injection of some drugs, for example thiopental. The patient was starved from midnight in preparation for the surgery.

The procedure performed was a right lateral thoracotomy and subtotal pericardectomy therefore the right lateral thorax was clipped to include the thoracic inlet and last rib. The clip was extended dorsally to the vertebrae and ventrally to include the sternum. The area was clipped and prepared for surgery by the nurse using the standard operating procedure for the practice (Box 1).

Box. 1Standard operating for surgical preparation of the patient

• Ensure the clippers are clean and all the teeth of the blades are aligned with none missing. Cleaning includes the use of standard clipper spray to disinfect the blades and trigene used on the handle.
• Confirm the area to be clipped with the surgeon for the case.
• Clip the fur first moving with the fur and then against it to help decrease the risk of ‘clipper rash’ occurring.
• Once clipping is completed, vacuum the area to remove any loose hair or debris including vacuuming the table.
• For the initial skin preparation a scrub solution of 4% chlorhexidine and water in equal parts should be made up in a sterilised green kidney dish.
• Place incontinence sheets around the area to be prepped to ensure a clean area for preparation.
• To prevent cross-contamination, non-sterile gloves should be worn and the area should be scrubbed using lint free gauze swabs. The surgical site should be scrubbed using a back and forth motion for 30 seconds, starting at the incision site and moving to the periphery. This should be repeated with a new swab every time until the swabs are clean.
• Dry swabs should be used to remove any contaminated scrub solution during the scrubbing procedure.
• The surgical area should then be covered in a clean incontinence pad and the patient transferred onto a clean theatre trolley to be moved through to the operating theatre.

Standard operating procedure for final skin antisepsis:

• Position the patient for the procedure due to be performed.
• The incontinence pad should be removed and disposed of.
• A final sterile skin sterilisation is carried out using a sterile, single use applicator containing a solution of 2% chlorhexidine gluconate and 70% isopropyl alcohol.
• Wearing non-sterile examination gloves, remove the applicator from the sterile package and hold the sponge facing downwards. DO NOT touch the sponge applicator.
• Squeeze the applicator to break the ampoule containing the antiseptic solution which releases it into the sponge.
• Apply the applicator over the incision site using a repeated up and down, back and forth strokes for at least 30 seconds before moving towards the periphery.
• Discard the applicator and leave the area to dry completely before being covered with sterile drapes.
• Any adverse reactions to skin antiseptics should be reported in the practice's adverse event reporting system.

Anaesthetic considerations for this case are listed in Box 2 and the drugs used for induction and maintenance of anaesthesia are listed in Table 2. Throughout the procedure parameter values were recorded every 5 minutes so that trends would be easily identified and actions taken as necessary. This included: SpO₂ using a pulse oximeter; body temperature using an oesophageal probe; electrical activity of the heart using an electrocardiogram (ECG); measurement of carbon dioxide concentration in respired gases using sidestream capnography; and invasive blood pressure using an arterial line. The broad spectrum antibiotic cefuroxine (Zinacef^©, GlaxoSmithKline) was administered by slow IV injection, at a dose of 20 mg/kg, every 90 minutes throughout the procedure to reduce the risk of infection developing.

Box. 2Anaesthetic considerations for the patient

• Pain or stimulation during the procedure.
• Hypothermia, as a large surface area of the patient will be exposed.
• Hypotension, which may be produced as a result of using a ventilator.
• Haemorrhage especially since the operating site is close to vascular structures and major blood vessels.
• Hypoventilation which may require the patient to be manually ventilated.

In theatre the patient was positioned in left lateral recumbency with the forelimbs extended cranially using limb ties in addition to wedges to prevent rotation of the body. This positioning not only allowed the anaesthetist to have access to the head, enabling the depth of anaesthesia to be assessed, but also provided access to the IV catheter. The initial surgical incision was made at level of fifth intercostal space and was then extended to incise the external muscles including the cutaneous trunci and latissimus dorsi. The intercostal muscles of the fifth rib space were incised to gain visualisation of the pericardium. Fluid within the pericardium was collected for analysis and two-thirds of the pericardium was excised. The heart was then visually inspected and palpated for any evidence of masses. A wire guided thoracostomy tube was placed into the right hand side of the thorax and a swab count was completed before closure. A swab count is an important step to reduce the risk of gossypiboma occurring (Jones, 2008). The intercostal spaces were closed using polydioxanone suture (PDS, Ethicon) with self-locking sutures. Muscle layers and subcutaneous tissue was closed with PDS suture material using simple continuous sutures. Skin layer was closed with staples. The thoracostomy tube was drained air and 10 ml of fluid immediately after closure.

The nurse set up the recovery environment in ICU for close observation and monitoring of the patient. This included the cot (moveable bed with collapsible barred sides) which was positioned in the centre of the room for easy observation and access of the patient. The cot was also angled so that the head of the patient would be higher than the body to prevent the abdominal contents compressingthe diaphragm and impinging respiratory function. It was then lined with incontinence pads and topped with a Vetbed^© (Vetfleece) to provide drainage and move fluids away from the patient's skin, minimising the risk of urine scald developing (Cooper et al, 2011). Further equipment provided included oxygen tubing, a facemask, a pulse oximeter, an infusion pump and fluid pump to allow administration of fluids and analgesics.

Once in the recovery environment the patient was placed into sternal recumbency to aid respiratory function (Day, 2014). Temperature was also closely monitored as the patient had become hypothermic throughout the surgical procedure: 35°C throughout and 34°C on readmission to ICU (normal range for a dog is 38.3–38.8 °C). This was despite measures being taken such as the use of a heat pad and blankets during pre-surgical preparation, Bair-Hugger^© (3M) in theatre and warmed fluids used for flushing as well as steps being taken to minimise the anaesthetic time. For this reason active warming methods, i.e. a Bair-Hugger^©, were used in recovery. Ideally hypothermia under anaesthetic and in the recovery period should be avoided. Side effects of hypothermia include: delayed drug metabolism resulting in a longer recovery period; cardiovascular depression; interference with haemostasis causing delayed wound healing; reduced immunity; arrhythmias and central nervous system depression (Welsh, 2009).

In recovery the patient displayed post epidural urine retention. A visibly large bladder on ultrasound influenced the decision of the VS to place an indwelling urinary catheter with a closed collection drainage system. This was carefully monitored and handled to reduce the risk of an ascending urinary tract infection occurring. This included ensuring that the urine collection bag was placed in a transparent, sealable bag (so levels of urine could be monitored visually to identify if the urinary collection bag needed to be drained sooner that specified) and placed in a box (to prevent damage to the bag that may result in bacteria entering the closed catheter system). The urine collection bag was also emptied every 2–4 hours. It was handled using appropriate hand hygiene with the use of disposable gloves and aprons. The volumes, as well as the visual characteristics of the urine produced were recorded. Further measures to assess urinary health could have also been carried out, such as periodically completing an in-house urine dipstick or specific gravity to check for early signs of infection, for example the presence of white blood cells or blood.

The patient was pain scored every 4 hours using the Glasgow composite pain scoring system (Reid, 2007) (Table 3) to ensure adequate analgesia was being given. The patient was given methadone every 4 hours in conjunction with a pain score immediately post operatively. This was then reduced to buprenorphine every 4 hours, 1 day post operatively due to consistently low pain scores (pain score under 4 on Glasgow composite pain score). Practice protocol dictates that a score higher than five or six is reported to the VS for rescue analgesia, however this was not necessary with this patient.

The thoracostomy tube was handled as per standard operating procedure (Box 3) to maintain asepsis and reduce the risk of infection occurring. Essential parameters, e.g. temperature, pulse, respiration and mucus membrane colour, were also monitored and assessed at least four times daily in the postoperative period, and these were normal.

Box. 3Standard operating procedure for the management of thoracostomy tubes

• Checking the chest drain — once daily
• Ensure the patient is adequately restrained.
• Collect all equipment (primapore^©, needle free bungs) before decontaminating hands and applying gloves.
• Remove bandaging if present.
• Palpate area and observe for redness, swelling, emphysema and discharge. Alert the nurse/veterinary surgeon to any abnormalities.
• Remove gloves wash hands.

Draining the chest

• Equipment required: disposable gloves, syringes, spirit swabs and kidney dish.
• Ensure the patient is adequately restrained.
• Collect all equipment before decontaminating hands.
• Wipe needle free bung with spirit soaked swabs and attach syringe and 3 way tap to on position and aspirate fluid/air.
• Once the syringe is full then switch 3 way tap off to expel syringe contents into the kidney dish without touching the syringe to the edge of the container.
• Repeat the process until there is no more air/fluid and you have negative pressure on aspiration.
• Switch 3 way tap to off and remove syringe.
• Wipe around bung with spirit soaked swab.
• Remove gloves and decontaminate hands.
• Record volume of fluid/air in hospital records.
• Report to veterinary surgeon if fluid looks particularly bloody and perform PCV/TS

Maintaining nutritional requirements proved a challenge for the nursing team. Although the nurses tried to tempt the patient to eat with freshly cooked chicken, hand feeding and removing the buster collar while the patient was supervised, no food was consumed. The decision was made by the VS to administer mirtazapine (appetite stimulant) which improved the patient's appetite, and the patient started eating normally.

Three days post surgery, the low amount of fluid and air produced by the thoracostomy tube and voluntary urination meant the patient was considered stable enough to have both the urinary catheter and thoracostomy tube removed.

Outpatient care

The patient was discharged 1 day later. Discharge instructions included: lead walks only; preventing jumping and playing for at least 10 days; monitoring the wound closely for signs of infection which included erythema, swelling and discharge. They were also given meloxicam (Metacam^©, Boehringer Ingelheim) a non-steroidal anti-inflammatory to provide analgesia and an anti-inflammatory action. Metacam was to be given once a day, orally, with food, and owners were given advice verbally on how to recognise pain, such as lameness, changes in appetite, behaviour or respiratory rate. The biopsy from the removed pericardium confirmed that no evidence of neoplasia was present.

The clinical examination at the follow-up appointment, 10 days later, was unremarkable and the owners displayed no concerns. An ultrasound revealed no free fluid in the thorax and the skin staples were removed at this point.

Discussion

Sub-total pericardetomies involve entry into the pleural cavity of the thorax and are therefore considered major surgical procedures. As such they have a high risk of complications occurring post-operatively which includes ‘pain, limb weakness, seroma development, incisional dehiscence and pulmonary dysfunction’ (Walsh et al, 1999)

Placement of a thoracostomy tube carries additional complications and risks for the patient. Incorrectly placed tubes can be detrimental and correct placement of the tube should be confirmed with a thoracic radiograph (Day, 2014). This extra procedure was not completed with this patient and may have been beneficial as it is an easy way to rule out this risk. In addition, damage or premature removal of the thoracostomy tube may result in a pneumothorax developing. This may be caused by patient interference however this can be minimised by close supervision and the use of Elizabethan collars (Carnell, 2008). However, even with these measures in place the patient could still cause damage by using their hind limbs and the surrounding environment (Jobson, 2016). Having the patient located in ICU was an ideal way to ensure close monitoring and prevented this complication arising. Once in recovery, drainage of the thoracostomy tube was completed. A pack cell volume (PCV) and total solid value was obtained from the fluid drained from the thoracostomy tube and compared to an arterial blood sample. Similarity in these values would indicate a haemorrhage from the surgical site and this would require intervention. This extra measure can be crucial for the recovery of the patient. Surgifix^© (available from Pioneer Veterinary Products) and Primapore^© (Smith & Nephew) were applied to protect the wound with the area being checked once daily, however if a bandage is applied it should be changed at least twice daily so the wound can be closely monitored for signs of infection (Day, 2014).

As with all surgical procedures, the risk of infection developing is a concern. It has been suggested that most surgical site infections are caused by contamination of the incision with microorganisms from the patient's own body (Roberts, 2013). Therefore the risk can be reduced by appropriate and effective precautions being taken in the perioperative stage. This includes evaluating: patient preparation; prevention of hypothermia which can dampen the immune response; theatre conduct; hand hygiene; equipment sterilisation; antibiotic therapy; swab and instrument tracking and postoperative management (Roberts, 2013). In aiming to minimise the time under anaesthesia it can be easy to inadvertently miss some critical steps along the way. The practice has therefore incorporated a surgical safety checklist (SSC) into the surgical preparation stage. The use of the SSC ensures that important steps are not bypassed as well as allowing potential problems to be recorded and prepared for, making it a highly useful tool which can be easily implemented into any veterinary practice (Clapham, 2015).

Incorrect management of the arterial catheter could also have resulted in severe complications for the patient. The arterial catheter was placed to allow more accurate blood pressure monitoring throughout the anaesthetic. In recovery it allows multiple blood samples to be taken with minimal stress to the patient as well as allowing accurate blood pressure recordings to be taken if needed. The catheter was placed as sterilely as possible with the area being prepared in the same way as the surgical site, hand hygiene (WHO five point handwash (WHO, 2017) with Sterilium^© (HARTMANN)), and sterile gloves were also used. During the surgery the catheter was connected to a continuous flushing system to take continuous readings, in recovery it was flushed every 2–4 hours aseptically using heparinised saline. It is vital that the catheter is clearly labelled as arterial injection of some drugs can have disastrous effects (Welsh, 2009). Once the catheter is no longer required it should be removed to minimise the risk of infection developing. A pressure bandage should be placed after removal to prevent haematoma formation (Roberts, 2016).

Pain is associated with all surgical procedures and adequate analgesia should be provided to remove unnecessary suffering. Uncontrolled pain can cause a variety of complications including: anorexia, delayed healing of wounds resulting in a slower recovery, and behavioural changes for example kennel guarding, aggressive behaviour or cause self trauma (Roberts, 2009). Adequate knowledge of how to recognise pain is essential in its treatment and management. Many veterinary practices have implemented pain scoring systems with the aim of setting a standardised method of assessing pain. The author's ICU use the Glasgow composite pain scoring system for dogs and it is located on the reverse of every day sheet, making it readily available for all members of staff. These pain scores, although useful, are a subjective assessment of the patient and should not be 100% relied on. The practice should also set an intervention point for the system at which point the patient's analgesia protocol should be re-evaluated. The presence of the thoracostomy tube has an additional benefit of allowing local anaesthetic to be placed down it therefore providing further analgesia if needed (Hoston Moore and Rudd, 2008); the patient discussed in this patient care report did not require this additional analgesia to be given.

The amount of postoperative pain may also be reduced by assessing the surgical approach used. No research has confirmed whether a medial or a lateral approach to thoracotomies result in more pain for the patient. Chanoit (2013) suggests that other factors to reduce pain may need to be considered such as the use of monofilament instead of wire for closing sternotomies, which is now commonplace in human surgery. Research is also being carried out into creating pericardial windows via thoracoscopy as opposed to doing an open pericardectomy (Case et al, 2013). However more study into this area is needed and it may become a viable and effective treatment option in the future.

Conclusion

As a student nurse the author was involved in all stages of the patient's nursing care from admission until discharge. Overall, in the author's opinion, this case is a good example of the whole veterinary team throughout the hospital communicating efficiently and in a professional manner as well as using standardised methods of practice to ensure the best care was given to the patient to achieve a positive outcome for the patient and its owners.

Key Points

• Sub-total pericardectomies are major surgical procedures and therefore come with a high risk of complications occurring both intra-operatively and in the recovery period.
• Pain management is vital for any postoperative patient. The use of a recognised pain score sets a standardised method to assess each patient and should be completed, as a minimum, before the administration of any analgesic.
• Thoracostomy tubes should be handled aseptically and monitored for signs of infection.
• Careful monitoring of the patient post operatively is necessary to quickly identify complications as well as preventing patient interference which could be detrimental.
• A surgical safety checklist (SSC) can be easily implemented into any veterinary practice and ensures standardised steps are taken for every surgery as well as allowing potential complications to be identified and prepared for.
• The practice wide approach to surgical cases can help ensure good patient outcomes from assessing patient preparation to surgical technique, communication with the owner and postoperative monitoring.