Page 147 - BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery, 2nd Edition

BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery

Skin wound healing, improve recovery and decrease hospitali-
zation times. Analgesia should be started prior to surgery.
The skin overlying the thorax is relatively loose laterally,
VetBooks.ir therefore facilitating closure of skin wounds. A robust operative bolus or constant rate infusion (CRI) administra-
Analgesic protocols should include pre-, intra- and post-
axial pattern flap based upon the thoracodorsal artery
tion of an opioid, either alone or in combination with
lies caudal to the scapula and can be used for recon-
struction of proximal thoracic limb or axillary wounds and ketamine and/or lidocaine CRIs. Mild sedation may be
required postoperatively, in particular following thoracic
large thoracic wall skin defects. The axillary flank fold wall reconstruction, but careful attention must be paid to
flap can be used to reconstruct sternal or ventral thoracic avoiding hypoventilation. The administration of intercostal
skin defects. The skin overlying the pectoral muscles is
nerve blocks perioperatively and local anaesthesia via
tightly tethered, meaning that minimal skin recruitment the thoracostomy tube postoperatively (Conzemius et al.,
is achieved following undermining at this site.
1994) may aid in postoperative analgesia. A subcutane-
ously implanted wound diffusion catheter is useful for
the administration of local anaesthesia for 24–48 hours
Anaesthetic management, postoperatively. Postoperative pain should be monitored
analgesia and postoperative care closely using a standardized pain score.
A non-steroidal anti-inflammatory drug should be
administered for a minimum of 10–14 days postoperatively,
Anaesthesia when not contraindicated, and this should be combined
A high level of anaesthetic knowledge, skills and monitor- with a stronger oral analgesic for a minimum of 5–7 days.
ing are required to meet the anaesthetic, oxygen and anal-
gesic requirements of thoracic surgery patients. Prior Postoperative care
to anaesthesia, general health status should be assessed.
A minimum database should include a complete blood A smooth and calm recovery from anaesthesia is important,
count, biochemistry, urinalysis and thoracic radiographs. and it may be necessary for someone to sit with the patient
Ideally, an electrocardiogram (ECG), blood pressure meas- to ensure they wake up quietly. This is particularly important
urement and pulse oximetry should also be performed. following chest wall reconstruction, as these patients do
Thoracic surgery patients are frequently hypoxaemic not have the normal protective barrier present between the
prior to surgery and each patient needs to be assessed skin and internal thoracic organs. Post operative flailing or
to determine whether premedication is appropriate. aggressive handling can disrupt the surgical site or poten-
Advantages of premedication include a calmer patient, tially cause thoracic visceral damage. Adequately thick bed-
less need for general anaesthetic during induction, poten- ding is essential for postoperative comfort.
tially less initial hypotension, easier administration of pre- Heart rate, ECG, temperature and blood pressure
anaesthetic oxygen, less struggling during intravenous should be monitored in the immediate postoperative
catheter placement and increased ability to place monitor- period and this is frequently continued on a regular basis
ing equipment prior to induction. Disadvantages of pre- for 24–48 hours. Animals seem to recover quickly once the
medication include respiratory depression, worsened thoracostomy tube is removed, which is usually deter-
hypoxaemia and potentially decreased cardiac output or mined by the degree of fluid or air production. If the thora-
hypotension. Preoxygenation is required for 5 minutes costomy tube is negative for air over 6–8 hours and is
prior to anaesthesia induction. producing minimal fluid, it is removed.
Basic anaesthesia monitoring, which should be per- Animals recovering from any thoracic surgery should
formed in all thoracic surgery patients, includes an ECG, receive supplemental oxygen until they can maintain ade-
indirect (Doppler or oscillometric) blood pressure meas- quate oxygenation on 21% oxygen (P aO 2 >60 mmHg, S aO 2
urement, capnography, pulse oximetry and audible pulse >90%) at sea level, or an alveolar–arterial oxygen gradient
monitoring (Doppler or oesophageal stethoscope). Direct <25 mmHg. Two hours of postoperative oxygen supple-
blood pressure and in-house blood gas analysis should mentation has been shown to decrease wound infection
also be available for most thoracic surgeries. It is safest to and improve tissue oxygen levels in humans (Greif et al.,
have a specific person dedicated to monitoring the animal, 2000). Oxygen supplementation is beneficial for a mini-
as the patient’s status can change quickly and dramati- mum of 12–24 hours following open thoracic surgery. It is
cally. In addition, an anaesthetic record should be kept important to keep the F iO 2 <60% during this time to
and, at an absolute minimum, the pulse rate, respiratory prevent oxygen toxicity (Lodato, 2006).
rate, blood pressure and temperature should be recorded Animals that have chronic lung atelectasis (e.g. due to
every 5 minutes. chest wall tumours that have been slow growing or chronic
Supportive care measures, which should be routinely diaphragmatic rupture) are susceptible to re-expansion
used or readily available, include fluid therapy (crystalloids pulmonary oedema. The risk of oedema developing can be
and colloids), analgesia, allogeneic blood products (fresh mitigated by applying a conservative ventilation strategy
frozen plasma, packed red blood cells, whole blood and/or intraoperatively (low tidal volume with a higher respiratory
albumin), supplemental oxygen, inotropes, vasopressors, rate) and gradually evacuating air from the pleural space
anti-arrhythmics, ventilatory therapy and emergency drugs postoperatively, whilst carefully monitoring respiratory
and equipment for cardiopulmonary–cerebral resuscitation. parameters. Pulmonary crackles on auscultation, respir-
Please refer to the BSAVA Manual of Canine and atory distress and hypoxaemia are all indications that
Feline Anaesthesia and Analgesia for further information. re-expansion pulmonary oedema may be occurring. This
is not a furosemide-responsive oedema and supportive
Analgesia care with oxygen is the best treatment. In severe situa-
tions, mechanical ventilation with positive end-expiratory
Thoracic surgery is very painful and multimodal analgesia pressure may be necessary.
is essential to decrease the doses of anaesthetic drugs, Ventilation should be taken into consideration for all
ameliorate the negative effects of pain on ventilation and thoracic surgery patients and, although it has not seemingly

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