Felis ISSN 2398-2950

Anesthesia: for thoracic surgery

Contributor(s): John Dodam, Sheilah Robertson, Polly Taylor, Claire Waters

Introduction

Alternatives
  • General anesthesia is a requirement for thoracic surgery, as there is need to control respiration by intermittent positive pressure ventilation (IPPV) once the thoracic cavity is opened to atmospheric pressure.

Preparation

Risk assessment

  • General clinical examination:
    • Include assessment of airway patency and identify any potential problems which could interfere with endotracheal intubation.
    • Percussion in cases of suspected pulmonary consolidation or fluid presence.
    • Auscultation.

Assess animals both before and after an episode of physical activity (degree of which to be determined cautiously depending on condition of animal) as may be compensating at rest.

Cyanotic animals are very poor anesthetic risks.

  • Radiography.

In cases of respiratory insufficiency standing lateral and dorso-ventral rather than ventro-dorsal views of the thorax are safer. Animals are less likely to struggle and avoids deterioration of respiratory insufficiency associated with standard lateral and ventro-dorsal views.

  • Hematology.
  • Biochemistry.
  • Electrolyte assay.
  • Urinalysis.
  • Arterial blood gas analysis.
  • Other ancillary aids as indicated by the presenting condition or other concurrent disease:
  • Animals with sub-clinical respiratory insufficiency or requiring thoracic surgery for non-respiratory conditions will fall into:
    • Class 3 (moderate risk)
    • Class 4 (high risk)
    • Class 5 (grave risk), depending on the severity of respiratory insufficiency and the presence of secondary or concurrent disease.

Standard pre-operative preparation

Specific

  • Treatment of conditions affecting animal's fitness for anesthesia and surgery to stabilize, eg pulmonary edema treated by diuresis. Hydrothorax, chylothorax, pneumothorax and ascites can be drained prior to emergency surgery.

Should be prepared to commence intravenous fluid administration to maintain circulating blood volume if large volumes of fluid are removed rapidly, accurate replacement is possible if central venous pressure   Central venous pressure  is monitored during the procedure

  • Bacterial respiratory infections should be treated with broad spectrum antibiotics.
  • Preoxygenate for a minimum of 5 minutes Preoxygenation 01 .
  • Preoxygenation can be carried out in an oxygen chamber or tent or by mask. The value is much reduced if the animal struggles.

Some animals may be relying on hypoxic drive to maintain respiration, monitor during preoxygenation to ensure continuing ventilation.

Oxygen therapy presents a fire hazard.

  • Place intravenous catheter (largest bore convenient) to ensure reliable intravenous access.
  • In critical cases place a central venous catheter in addition, necessary to monitor central venous pressure and useful for the rapid infusion of large volumes of fluid as required.
  • Prepare the surgical site, as far as possible without stressing the animal or placing it into lateral or dorsal recumbency, before anesthetic induction.

Requirements

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Procedure

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Induction

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Maintenance

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Recovery

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Further Reading

Publications

Refereed papers
  • Clarke K W (1977)Anaesthesia for open chest surgery. J Small Anim Pract18, 585-590. (An overview.)PubMed
  • Berg RJ & Orton EC (1986)Pulmonary function in dogs after intercostal thoracotomy: comparison of morphine, oxymorphone, and selective intercostal nerve block. Am J Vet Res.47(2), 471-474.PubMed

Other sources of information

  • Hall, L W and Taylor, P M (1994) EdsAnaesthesia of the Cat.London: Bailliere Tindall. pp152-153, 268, 294-301. ISBN 0 7020 1665 9
  • Bedford, P G C (1919)Small Animal Anaesthesia, The Increased Risk Patient.London: Bailliere Tindall. pp31-33, 53-71. ISBN 0 7020 1501 6.
  • Hall, L W (1982)Relaxant drugs in small animal anaesthesia.In Proceedings of the Association of Veterinary Anaesthetists of Great Britain and IrelandSupplement to10, 144-155.
  • Brouwer, G J (1989)Anaesthesia for thoracic surgery.In Manual of Anaesthesia for Small Animal Practice.Ed A D R Hilbery. Cheltenham: British Small Animal Veterinary Association. pp95-99. ISBN 0 905214 09 9.


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