Page 1897 - Cote clinical veterinary advisor dogs and cats 4th

950.e2 Subcutaneous Emphysema

Subcutaneous Emphysema Client Education
Sheet
VetBooks.ir

tissues by unidirectional valve action of the
BASIC INFORMATION
airway trauma. TREATMENT
Definition ○ Rupture of dorsal tracheal membrane (cats Treatment Overview
Accumulation of air in subcutaneous tissues > dogs) Most patients heal spontaneously in 1-2 weeks.
○ Rupture of dorsolateral or ventrolateral More severe trauma, such as cervical bite
Epidemiology tracheal annular ligament wounds, requires surgical exploration.
SPECIES, AGE, SEX ○ Penetrating wound in cervical area
More often seen in cats than in dogs; cats have Specific causes: Acute General Treatment
a thin dorsal tracheal membrane compared with • Related to endotracheal intubation • In animals without respiratory discomfort
dogs ○ Overinflation of endotracheal tube cuff ○ Supportive care while awaiting spontane-
○ Use of a stiff stylet to guide the endo- ous absorption of the air
RISK FACTORS tracheal tube through the larynx can ○ Cage rest
• Endotracheal intubation, especially in cats puncture trachea. • In animals with mild discomfort
• Jugular venipuncture ○ Manipulation of the head without discon- ○ Consider light sedation.
• Trauma to conducting airways, especially necting the endotracheal tube ○ Removal of air by an 18- or 16-gauge
trachea • Surgical (e.g., airway surgery, maxillary needle. Air may be gently massaged
• Penetrating wounds surgery) toward the needle for evacuation. Needle
• Anaerobic infection of subcutis • Traumatic suction alone may not be able to remove
• Surgery of the airways, especially upper ○ Bite wounds the trapped air. Air removal by skin stab
airway surgery ○ Lacerations or penetrating foreign incisions is not advised.
objects, including jugular venipuncture, ○ Repeat this procedure as needed to keep
ASSOCIATED DISORDERS transtracheal aspirates, and misplacement the animal comfortable.
• Pneumomediastinum of laparoscopy needles ○ Penrose drains can be placed into the
• Pneumoretroperitoneum • Infectious subcutis (similar to treating a subcutane-
• Pneumopericardium ○ Inoculation of gas-forming bacteria (e.g., ous abscess) to allow continuous drainage
• Pneumothorax anaerobes) during penetrating injuries of air. This is less labor intensive and
• Idiopathic more effective than repeated percutaneous
Clinical Presentation centesis.
HISTORY, CHIEF COMPLAINT DIAGNOSIS ○ Analgesia: butorphanol 0.2-0.4 mg/kg
• History of recent anesthesia with intubation IV, IM q 2-4h or buprenorphine 0.01-
• History of trauma or head/neck surgery Diagnostic Overview 0.03 mg/kg IV, IM q 6-8h
• History of recent jugular venipuncture, A history of recent intubation or tracheal • In animals with recurrent/refractory subcuta-
transtracheal aspiration, or other penetrating trauma with or without acute onset of increased neous emphysema and progressive respiratory
medical procedure of the neck body size is suggestive. The characteristic bubble distress
• Dyspnea, discomfort wrap–like feeling on palpation and/or the ○ If dyspnea is due to compression of the
• Rapid onset of swollen or bloated appearance subcutaneous air on radiographs can confirm airways by trapped air in the subcutis
of the body, initially around the neck but the diagnosis. or mediastinum, trapped air should be
may progress to the whole body allowed to drain, producing improved
Differential Diagnosis respiratory effort.
PHYSICAL EXAM FINDINGS Tracheal avulsion/rupture; radiographs reveal ○ Surgical repair of the trachea if con-
Animal may manifest respiratory discomfort. physical separation of the trachea; surgery is servative measures are inadequate or if
Characteristic crackling sensation (crepitus) on required (p. 986). radiography suggests tracheal avulsion/
palpation of the skin overlying the trapped air rupture.
is pathognomonic. Initial Database ○ Analgesia: fentanyl 2-5 mcg/kg/h IV or
• Initially focal (especially around the neck) • CBC and serum biochemical profile: gener- other opioid agonists as indicated
and progressing rapidly to affect the whole ally unremarkable for cases of airway trauma;
body suggests airway perforation/rupture as may show evidence of infection (neutrophilia, Drug Interactions
source; dyspnea, discomfort may or may not left shift, toxic changes) if subcutaneous Avoid subcutaneous drug administration until
be present. emphysema is due to anaerobic infection normalized.
• Focal in an animal showing signs of severe of the subcutis (rare).
illness; may suggest infection-related subcu- • Radiographs of neck and thorax show pres- Possible Complications
taneous emphysema. A meticulous search for ence of air trapped under the skin. Depending on the cause of the subcutaneous
penetrating wounds is indicated. emphysema, tracheal rupture, pneumothorax,
Advanced or Confirmatory Testing pneumomediastinum, and pneumoretroperi-
Etiology and Pathophysiology Tracheoscopy: toneum are possible, as is sepsis (if bacterial
• A break in the integrity of the airway at • Lesions may be difficult to visualize. infection of the subcutis occurs).
any point between the pharynx and terminal • Negative finding does not rule out tra-
bronchioles cheal trauma as cause for subcutaneous Recommended Monitoring
• An independent source of gas formation emphysema. Evaluate rate and depth of respiration as
(bacteria) in the subcutis • CT scan of trachea may be required to detect an indicator for the level of comfort in the
• With any of the following three mechanisms, presence and/or extent of tracheal rupture. animal and consider the need for surgical
air may remain trapped in the subcutaneous • Surgical exploration if severe. treatment.

www.ExpertConsult.com