Anesthesia: for ruptured diaphragm

Introduction

• General anesthesia is a requirement for ruptured diaphragm repair.

Preparation

Risk assessment and management

• Priority in the management of the recently traumatized cat    is given to fluid therapy    to restore circulating blood volume and analgesia    .
• In the absence of life-threatening injuries requiring immediate surgery, eg tension pneumothorax, anesthesia is best postponed for 24 hours. This allows time for:
  • Cardiovascular system to stabilize. Myocardial injury, eg contusion, may not become apparent for 24 hours and predisposes to cardiac arrhythmias.
  • Endocrine system to stabilize.
  • Full extent of injuries to be assessed eg urinary system damage not readily detected until time has elapsed for urine output to be monitored.

General clinical examination

• Include assessment of airway patency and identify any potential problems which could interfere with endotracheal intubation.
• Auscultation of the thorax.
• Percussion of the thorax.
• Mucous membrane color and capillary refill time.

Cyanotic animals are very poor anesthetic risks.

Radiography

Ventral lungs will be compressed by abdominal viscera so avoid positioning which will tend to compress the remaining normal lung in the dorsal regions. Standing lateral and dorso-ventral rather than ventro-dorsal views are safer.

Ancillary Test

• Hematology.
• Biochemistry.
• Electrolyte assay.
• Urinalysis.
• Other ancillary aids as indicated by other injuries or concurrent disease eg electrocardiography    , ultrasonography.
• Animals with diaphragmatic rupture will fall into:
  • Class 4 (high risk)
  • Class 5 (grave risk)
  depending on the severity of respiratory impairment, other injuries and concurrent disease.

Specific preoperative preparation

ALWAYS preoxygenate for a minimum of 5 minutes.

• Preoxygenation can be carried out in an oxygen chamber or tent, by mask or via a naso-pharyngeal tube. The value is much reduced if the animal struggles.

Oxygen therapy presents a fire hazard.

• An intravenous catheter should be placed prior to induction to ensure reliable intravenous access.
• Prepare the surgical site, as far as possible without stressing the animal or placing it in lateral or dorsal recumbency, before anesthetic induction. After premedication and preoxygenation many cats will allow themselves to be supported in a standing position with the forelimbs raised for preparation.
• Have equipment required for desensitization of the larynx and intubation ready and to hand.

Sources

Publications

Refereed papers

• Clarke K W (1977) Anesthesia for open chest surgery. J Small Anim Pract 18 , 585-590. (An overview.) PubMed

Other sources of information

• Hall, L W and Taylor, P M (1994) Eds anesthesia of the Cat. London: Bailliere Tindall. pp152-153,266-268, 294-301. ISBN 0 7020 1665 9
• Bedford, P G C (1919) Small Animal anesthesia, The Increased Risk Patient. London: Bailliere Tindall. p31-33, 38-43,53-71. ISBN 0 7020 1501 6.
• Hall, L W (1982) Relaxant drugs in small animal anesthesia. In Proceedings of the Association of Veterinary anesthetists of Great Britain and Ireland Supplement to 10 , 144-155.
• Brouwer, G J (1989) anesthesia for thoracic surgery. In Manual of anesthesia for Small Animal Practice. Ed A D R Hilbery. Cheltenham: British Small Animal Veterinary Association. pp95-99. ISBN 0 905214 09 9.