This patient care report highlights and discusses the veterinary nursing interventions implemented postoperatively following a feline undergoing a pericardiectomy. The pericardium is a thin sac surrounding the heart, which is attached to phrenicopericardial ligaments to fix the position of the heart to aid in maintaining cardiac shape (French, 2010). The pericardium also plays an important role in protecting the heart (French, 2010). Pericardial effusion can occur; this is the accumulation of fluid in the pericardial cavity, located between the visceral and parietal layers of the pericardium. Pericardial effusion is a life threatening condition, therefore emergency interventional procedures are vital to the survival of the patient. Pericardial effusion is associated with peritoneopericardial diaphragmatic hernias, neoplasia, cardiomyopathies, uraemia, systemic infection, concurrent feline infectious peritonitis (FIP) and idiopathic pericarditis (Hall et al, 2007).
Signalment:
- Species:Feline
- Breed:Domestic Short Hair
- Gender:Male (neutered)
- Age:4 years old
- Weight:5.35 kg
Admission and patient assessment
The patient presented as an emergency referral following a 10-day history of lethargy, hyporexia, urethral obstruction which was previously resolved and dyspnoea due to pleural effusion. 90 ml of serosanguinous pleural fluid was aspirated by bilateral thoracocentesis to relieve dyspnoea by the referring veterinary surgeon. On arrival and physical examination, cardiac auscultation revealed a grade two (II) heart murmur, with muffled heart sounds and no presence of arrhythmias or gallop sounds. He was bright and responsive with a respiration rate of 36 breaths per minute (bpm) and mild inspiratory and expiratory effort. Rectal temperature was normal.
Veterinary investigations and diagnosis
Echocardiography and an electrocardiogram (ECG) were performed by the cardiologist to reveal: moderate pericardial effusion; moderate pleural effusion (Figures 1 and 2); and mild peritoneal effusion. Hyperechoic structures were visualised within the pericardial effusion, consistent with a thrombus or soft tissue. There was no evidence of myocardial masses. The patient was restrained in lateral recumbency with flow-by oxygen administered with a mask. If a patient is distressed and increasingly dyspnoeic in recumbency, a standing echocardiogram can be completed to prevent deterioration of the patient's condition. Cardiac tamponade as a result of pericardial effusion was evident on echocardiogram. Cardiac tamponade reduces ventricular filling due to intrapericardial pressure compressing and often collapsing the right atrium (Scruggs and Bright, 2010), resulting in right-sided heart failure (Zoia et al, 2004). From this di-agnosis, pericardiocentesis and thoracocentesis were performed as an emergency procedure to relieve intrapleural and intrapericardial pressure on the heart (Boxes 1 and 2).
Box 1.Equipment required for pericardiocentesis
- Clippers with intact clipper blade (size 40)
- Swabs
- Skin preparation solution e.g. chlorhexidine
- Surgical spirit
- 2% lidocaine (for local anaesthesia)
- 20 g intravenous catheter or butterfly catheters (dependent on clinician choice)
- Range of syringes (5 ml, 10 ml, 20 ml)
- Sterile gloves
- Sterile fenestrated drape
- Sterile plain drape
- Scalpel blade
- Three-way tap
- Intravenous fluid extension line
- Sample tubes — EDTA and plain serum blood tubes
- Kidney dish
- Sedative drugs
- Echocardiography machine (if available)
- Crash box
- Electrocardiogram (ECG) machine
- Supplementation of oxygen (Richmond, 2018)
Box 2.Pericardiocentesis procedure
- The patient is placed in left lateral recumbency
- The right lateral hemi-thorax is clipped and aseptically prepared for an incision with chlorhexidine followed by a 1.5 ml Chloraprep™ scrub
- The veterinary surgeon may then infiltrate the incision site with injectable lidocaine
- A small incision is made into the site and a catheter is introduced
- A fluid extension line, 3-way tap and syringe are attached to the catheter. An assistant will aspirate the fluid slowly
- The fluid may be stored for further analysis in the form of a cytology smear or into an EDTA and plain serum blood tube
- The fluid aspirated should be recorded and discarded. Details to include when recording should include colour, consistency and amount aspirated
The patient was transported into a kennel for 24 hours of observation for another accumulation of effusion with the option of oxygen supplementation if required. The following medication was prescribed to the patient:
- Furosemide 1 mg/kg intravenously every 4 hours — a potent loop diuretic prescribed as a trial to resolve potential effusion as a result of cardiac origin
- Amoxicillin/clavulanic acid 20 mg/kg intravenously every 8 hours — an antibiotic to eliminate any potential infectious cause of re-occurring pericardial and pleural effusion.
After an initial 24 hours of hospitalisation, a follow-up echocardiogram revealed another significant pleural and pericardial effusion with cardiac tamponade, which warranted further investigation of the thorax and abdomen by computed tomography (CT). Pericardiocentesis and thoracocentesis were performed to relieve intracardiac pressure and to allow better visualisation of the thorax during diagnostic imaging; 173 ml of pericardial and pleural fluid were drained. The diagnostic imager reported moderate cranial mediastinal and sternal lymphadenopathy, possibly due to the inflammatory process or neoplasia. Generalised cardiomegaly was also reported alongside thickening of the left ventricle and an enlarged left atrium — consistent with hypertrophic cardiomyopathy (HCM), which was confirmed on echocardiography.
Surgical intervention
A subtotal pericardiectomy by medial sternotomy approach was performed. There was a large amount of serosanguinous pericardial and pleural effusion present on incision, which was drained. The thoracic cavity was flushed with warm sterile saline and samples were collected from the excised pericardium, mediastinal pleura and sternal lymph nodes for histopathology, culture and polymerase chain reaction (PCR). A thoracostomy tube was placed during closure of the sternebrae to allow repetitive draining of the pleural space following surgery (Day, 2014). The thoracostomy tube was placed in the right hemithorax and secured with roman-sandal sutures. Following thoracic surgery, thoracostomy tube placement should always occur to allow aspiration of air remaining in the pleural space as well as any build up of fluid post-operatively (Halfacree, 2011).
Discussion of nursing interventions
Pain management
Creation and implementation of a multi-modal analgesia protocol is necessary in combating postoperative pain (Richmond, 2005). Postoperative pain can manifest into a number of physiological dysfunctions, such as: hypoventilation, ileus, anuria (MacFarlane, 2018), as well as aggression resulting in a fractious patient to nurse. Table 1 displays the analgesia plan created and used for the patient during the peri-operative period to reduce pain.
Table 1. Analgesia protocol for the patient during the peri-operative period
| Analgesia given | Analgesia plan for drug | Dose |
|---|---|---|
| Methadone | Given as premedication before surgery intravenously | 0.3 mg/kg Single dose given |
| Morphine | Given into the epidural space by epidural performed by the anaesthetist. The morphine given was preservative free | 0.2 mg/kg Single dose given |
| Ketamine | Given as a constant rate infusion (CRI) delivered intravenously intra-operatively and postoperatively. However, the patient became dysphoric once awake from anaesthesia and was no longer given after 1 hour postoperatively | 0.2 μg/kg/minute CRI |
| Bupivacaine | Administered through the drain to deliver local anaesthesia to the surgical site. Began administration postoperatively. Careful monitoring needed to be given for signs of local anaesthesia toxicity such as patient tremors | 0.7 mg/kg Administered every 8 hours regardless of pain score |
| Methadone | The opioid of choice for immediate postoperative analgesia. The dose was decided based on the patient's pain score. Initial dose of 0.1 mg/kg and increased to 0.2 mg/kg if the patient did not respond to the initial lower dose | 0.1–0.2 mg/kg Administered every 4 to 6 hours dependent on pain score. Administered if pain score exceeds five |
| Buprenorphine | The opioid of choice 20 hours post-operatively. The patient's methadone was discontinued at this point. Administered intravenously depending on the pain score of the patient | 0.01 mg/kg Administered every 4 to 6 hours dependent on pain score. Administered if pain score exceeds five |
Pain scoring
Nurses play a vital role in assessing pain as they have the most contact with the patient during the period of hospitalisation. The Glasgow Feline Composite Measure Pain Scale is useful in linking a point of intervention with a score that has a standardised protocol (Reid et al, 2017). Figure 3 displays The Glasgow Feline Composite Measure Pain Scale which is used within the hospital to score whether an opioid should be given alongside the other analgesics in the patient's protocol. The patient was regularly assessed at a minimum of every 4 hours for signs of acute postoperative pain.
For the first 12 hours postoperatively the patient only received one dose of methadone alongside the other analgesics prescribed due to low pain scores recorded. At 20 hours post surgery, the clinician decided to replace methadone with buprenorphine as the opioid of choice. He was subsequently given one dose of buprenorphine due to having a pain score of eight.
Maintenance of the thoracostomy tube
The thoracostomy tube can also be termed a chest drain or thoracic drain within the veterinary practice. Management of the thoracostomy tube postoperatively is the role of the registered veterinary nurse (RVN); the RVN should aspirate fluid from the pleural cavity at regular intervals, maintain patency of the tube, and deliver local anaesthesia through the tube while following a thoracostomy tube care protocol (Box 3). The incorrect maintenance of a thoracostomy tube can increase the risk of patient morbidity and mortality (Day, 2014). The thoracostomy tube site was dressed with an absorbent adhesive dressing (Primapore©, Smith & Nephew) to cover the surgical and tube site. The thoracostomy tube was wrapped in swabs to prevent damage to the tube and reduce the risk of infection. The patient's thorax was dressed in a tubular elastic net bandage (Surgifix©, BSN Medical) to secure the tube in place (Carnell, 2008) (Figure 4).
Box 3.Patient thoracostomy tube care protocol
- Drainage should occur every 4 hours and all air/fluid aspirated should be recorded (ml)
- The patient should be restrained appropriately during draining to prevent pneumothorax
- When handling the thoracostomy tube, use an aseptic technique — wear gloves, use clean syringes and do not touch sterile ends of bungs
- Suction using less than 1 ml of negative pressure to prevent pleural damage
- Ensure the gate clamp, bungs and 3-way-tap are secure always or use a centesis valve to prevent pneumothorax
- The tube site should be checked and cleaned at least once daily
- Monitoring for subcutaneous emphysema is important — alert clinician if there is a concern
- The animal should be wearing a buster collar at all times to prevent patient interference
- Cover the entry site with a dressing (Primapore, Smith & Nephew) and tubular elastic net bandage (Surgifix, BSN Medical)
- All findings should be recorded on a thoracostomy tube record
- Alert the clinician if any of the following are noted: dyspnoea, patient dullness/depression, cyanosis, nature of fluid changes, volume of fluid aspirated increases, subcutaneous emphysema or air is drained
Thoracostomy tubes are also used to administer local anaesthesia to provide additional analgesia by blocking specific local nerve pathways (Carnell, 2008). The patient was prescribed bupivacaine (Table 1). Carnell (2008) states that bupivacaine will provide the patient with several hours of analgesia. Bupivacaine is injected into the thoracostomy tube and flushed through with a small amount (2 ml) of sterile saline to advance the local anaesthesia through the length of the thoracostomy tube. The patient was monitored for signs of local anaesthesia toxicity during the period of administration.
The patient's thoracostomy tube was drained every 4 hours for 3 days postoperatively until there was no longer large quantities of air or fluid being aspirated from the drain. It is important to record how much air and fluid was aspirated and the appearance of the fluid to monitor for any potential postoperative complications. Table 2 displays the patient's thoracostomy tube record over the period of placement. Draining was always completed before administration of bupivacaine to prevent re-aspiration of bupivacaine. Once there was consistently a small amount of fluid being aspirated on day three of placement, the thoracostomy tube was removed by a RVN. The incision site of the thoracostomy tube was covered by another adhesive absorbent dressing (Primapore©, Smith & Nephew).
Table 2. The patient's thoracostomy tube draining record from placement to removal
| Date | Time | Amount aspirated |
|---|---|---|
| 29/11/2018 | 12 am | 50 ml air & 10 ml serosanguinous fluid |
| 30/11/2018 | 4 am | 10 ml serosanguinous fluid |
| 30/11/2018 | 8 am | 7.5 ml serosanguinous fluid |
| 30/11/2018 | 12 pm | 3.4 ml serosanguinous fluid |
| 30/11/2018 | 4 pm | 12 ml serosanguinous fluid |
| 30/11/2018 | 8 pm | 6 ml serosanguinous fluid |
| 01/12/2018 | 12 am | 7 ml serosanguinous fluid |
| 01/12/2018 | 4 am | 5 ml serosanguinous fluid |
| 01/12/2018 | 8 am | 3 ml serosanguinous fluid |
| 01/12/2018 | 12 pm | 12 ml serosanguinous fluid |
| 01/12/2018 | 4 pm | 7 ml serosanguinous fluid |
| 01/12/2018 | 8 pm | 10 ml serosanguinous fluid |
| 02/12/2018 | 12 am | 5.5 ml serosanguinous fluid |
| 02/12/2018 | 4 am | 3 ml serosanguinous fluid |
| 02/12/2018 | 8 am | 5 ml serosanguinous fluid thoracostomy tube removed |
Correction of hydration and nutrition
The patient was estimated to be 8% dehydrated (based on physical examination and blood work analysis) postoperatively and therefore dehydration was a concern. Due to the patient's concurrent hypertrophic cardiomyopathy (HCM), large doses of intravenous fluid therapy was contraindicated alongside occult cardiac disease (Pascoe, 2012). Various methods of rehydration were implemented to correct dehydration while preventing the onset of congestive heart failure (CHF) by fluid overload.
Furosemide is a potent loop of Henle diuretic (Côté, 2017) which increases urine production and therefore the patient is often polydipsic and polyuric (Uechi et al, 2003). Furosemide administration poses a risk of further dehydration to the patient. Furosemide was administered as a preventative measure for 3 days pre-operatively and the patient remained polydipsic and polyuric into the postoperative period. A constant access to water was available as a method of rehydration and the amount consumed was recorded to measure ins and outs.
The patient was administered a low dose of intravenous fluid therapy (IVFT). He was prescribed isotonic crystalloid fluids (Ringer's lactate) at 1.5 ml/kg/hour infused with 60 mmol/litre of potassium chloride (KCl) due to the patient's concurrent postsurgical hypokalaemia, possibly due to diuretic administration. The patient was also administered an oral potassium supplementation. Venous blood samples were taken every 12 hours to reassess hypokalaemia. Hypokalaemia was corrected within 24 hours postoperatively.
The patient had a good appetite during the period of hospitalisation — the patient's daily recommended calorie intake (RER) was calculated and he was placed on a diet of Royal Canin Gastrointestinal wet food, which has a high water content to increase water intake. If a patient does not have a strong appetite during hospitalisation, it is recommended to place a naso-oesophageal (NO) feeding tube to provide enteral nutrition as well as water delivered through the tube for rehydration. NO tubes can be placed without the need for general anaesthesia, which is ideal for critical patients as a short-term nutritional intervention for the anorexic patient (Gajanayake, 2015).
Conclusion and recommendations for the future
Results from the samples sent to the laboratory showed no evidence of infectious microorganisms or neoplasia present within the pericardium or lymph nodes sent for histopathology — this is suggestive of a true idiopathic pericardial effusion. The patient returned to the practice 2 weeks postoperatively, he presented bright and owners reported him recovering well at home. No effusion was present on echocardiogram and the surgical site was clean and free of infection. This case sets a positive example of the importance of the RVN and their heavy involvement in the postoperative care. The care provided was of a high standard and provided a holistic approach to every need of the patient.
KEY POINTS
- Registered veterinary nurses play an important role in the investigation, diagnosis and treatment of pericardial effusion, from patient admission to discharge.
- Pericardial effusion is an emergency and pericardiocentesis should be performed as soon as possible (depending on patient stability) to prevent cardiac tamponade and patient deterioration.
- It is vital to deliver multi-modal analgesia peri-operatively alongside regular pain scoring to identify when additional analgesia administration is required.
- Correct protocols must be implemented when managing the thoracostomy tube to prevent infection and to maintain patency of the thoracostomy tube.
- Registered veterinary nurses should be comfortable in assessing the patient's hydration status to aid the veterinary surgeon in correcting hypovolaemia postoperatively.