Download spontaneous pneumothorax

SPONTANEOUS PNEUMOTHORAX
Shelley Smith, DVM
Emergency and Critical Care Intern
Christopher G. Byers, DVM, DACVECC, DACVIM (SAIM)*
Director, Intensive Care
VCA Veterinary Referral Associates
Gaithersburg, Maryland
S
pontaneous pneumothorax is an accumulation of
free air or gas in the pleural space in the absence
of traumatic or iatrogenic causes. Primary spontaneous pneumothorax develops from the rupture of pulmonary bullae or blebs without underlying disease.
Pneumothorax as a sequela of pulmonary disease is
termed secondary spontaneous pneumothorax. The
free air in the pleural space results from chronic
inflammation, weakening of the pleura, and pulmonary destruction. Tension pneumothorax, a lifethreatening condition, occurs when air accumulates
via a one-way valve effect during inspiration, allowing
air to enter but not leave the pleural space.
Rupture of pulmonary bullae or blebs is the most
common cause of spontaneous pneumothorax, occurring in 36% to 68% of cases. Bullae and blebs are differentiated based on the layer of the pleura or
parenchyma involved. Pulmonary blebs occur when
air escapes from the lung, such as through a ruptured
alveolus, and collects between the visceral pleura and
the lung parenchyma. They are typically less than one
to several centimeters in diameter. Bullae are air-filled
spaces within the lung parenchyma resulting from
confluence of adjacent alveoli. Bullae vary in size and
are ultimately confined by the connective tissue septa
within the lung and the visceral pleura.
Clinical signs of spontaneous pneumothorax are
secondary to the decrease in lung expansion and
venous return caused by the volume of air trapped
within the pleural cavity and the resulting compromise
of the cardiovascular and respiratory systems. The
severity of clinical signs is, therefore, related to the
amount of escaped air and the loss of negative
intrapleural pressure.
Historical Information
Gender and Age Predisposition
• None.
*Dr. Byers discloses that he has received financial support
from Dechra Pharmaceuticals, Waltham, and Animal Clinical Investigation LLC.
of CARE: e m e R g e N C y
Owner Observations
• Tachypnea and dyspnea.
• Anxiety.
• Decreased appetite.
• Decreased exercise tolerance.
• Vomiting.
• Cough.
Other Historical Considerations/Predispositions
• Primary spontaneous pneumothorax has not been
identified in cats, and secondary spontaneous pneumothorax has been reported only rarely in cats,
likely secondary to feline asthma.
Physical Examination Findings
•
•
•
•
Pale or cyanotic mucous membranes.
Tachypnea and/or dyspnea.
Tachycardia.
Decreased breath sounds dorsally; muffled heart
sounds.
• Hyperresonant on thoracic percussion.
• Poor femoral pulse quality.
Laboratory Findings
• Complete blood count, serum biochemical profile, and urinalysis are usually within normal limits. $
• Pulse oximetry and arterial blood gas analysis may
reveal evidence of hypoxemia. $
Other Diagnostic Findings
DIAGNOSTIC CRITERIA
STANDARDS
Breed Predisposition
• Siberian huskies are overrepresented.
• Possible increased risk for medium- to large-breed
dogs.
• Unstable patients with a high index of suspicion for
pneumothorax should not undergo imaging procedures such as radiography, ultrasonography, or
computed tomography (CT). Instead, thoracocentesis should emergently be performed (Box 1).
— Thoracocentesis may be diagnostic and therapeutic. Aspiration of air during thoracocentesis
confirms the diagnosis of pneumothorax. $
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BOX 1. TIPS FOR PERFORMING
THORACOCENTESIS
• Place the patient in lateral or sternal recumbency.
To minimize patient stress, the patient can stand
or sit during the procedure.
• mild sedation with butorphanol (0.2–0.4 mg/kg
Im) or morphine (0.01–0.05 mg/kg Im) may be
necessary. $
• Determine the site for thoracocentesis based on
auscultation, patient position, and radiographic
findings. Blind thoracocentesis is performed at the
7th to 9th intercostal space (ICS) either with the
patient in sternal recumbency at the mid to upper
thorax or with the patient in lateral recumbency at
the highest point (midthorax). If the patient is in the
standing or sitting position, perform the procedure
as if the animal were in sternal recumbency.
• Clip and prepare the site using sterile technique.
• The subcutaneous tissue and the pleura can be
infiltrated using 2% lidocaine (1–2 mg/kg) or
bupivacaine (1–2 mg/kg). $
• Attach a 19-gauge butterfly catheter or a 20-, 18-,
or 16-gauge over-the-needle catheter to extension
tubing, a three-way stopcock, and a large syringe
(20–60 mL).
• Slowly advance the needle or catheter cranial to
the rib, angling caudally and ventrally to enter the
pleural space just medial to the rib. This avoids
iatrogenic lung laceration, especially when using
a sharp needle.
• Use care to avoid the large vessels associated with
the posterior segment of the rib margins.
• Perform aspiration until negative pressure is
attained. The needle or catheter may need to be
withdrawn a few millimeters at a time to maintain
the catheter in the pleural space.
• Radiographic evidence supportive of spontaneous
pneumothorax includes increased width of an airfilled pleural space, partial pulmonary collapse,
retraction of lung margins from the chest wall, and,
in a lateral view, elevation of the heart off the sternum. Radiographs are a relatively poor modality for
consistently identifying bullae and blebs. $–$$
• The TFAST (thoracic focused assessment with
sonography for trauma) ultrasonography method
may be used to check for pneumothorax. $–$$
— Ultrasonography is performed bilaterally at the
7th to 9th intercostal space (ICS) on the dorsolateral thoracic wall to investigate the presence
of the glide sign. The glide sign is created by the
normal forward and backward motion of the
lung along the chest wall during respiration.
Lack of this sign is suggestive of an air interface
between the lung and chest wall, and, if indicated, therapy should be instituted.
— The TFAST method also includes imaging at the
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5th to 6th ICS on the ventrolateral thoracic
wall. The ultrasonographer’s window is shifted
cranioventrally to scan for pleural and pericardial fluid if clinically suspected.
• CT has been used in humans as a more sensitive
method for detection of bullae and blebs than radiography. $$$–$$$$
— CT should not be performed to diagnose pneumothorax in cases of respiratory distress. In
cases of severe respiratory compromise, stabilization procedures such as needle thoracocentesis should be performed before imaging.
— Correction of pneumothorax with either thoracocentesis or chest tube placement should be
instituted before anesthetizing the patient for CT.
— Placement of unilateral or bilateral chest tubes
is indicated when severe pulmonary disease is
suspected because there are times during CT
when the veterinarian is separated from the
patient.
— Care should be taken when anesthetizing and
ventilating these patients. Intermittent positivepressure ventilation may rupture intact bullae
or accelerate air leakage from the damaged
lung. Pressures in excess of 10–12 cm H2O
should be avoided.
— In a recent study in dogs, almost 2.5 times as
many lesions were identified with CT as with
radiography.
— Blebs and bullae appear as areas of low attenuation and vascular alteration on CT.
— CT allows identification of more lesions, better
definition of lesion size and locations, and better differentiation of anatomic structures and
their relationship to the lesions. The superiority
of CT over radiography aids in the surgical
approach. However, CT does not eliminate the
requirement for a thorough surgical exploration
of the thorax.
Summary of Diagnostic Criteria
• History of acute or chronic respiratory distress.
• Decreased breath sounds dorsally on thoracic auscultation.
• Radiographic, ultrasonographic, or computed tomographic evidence of air or gas in the pleural space.
• Aspiration of air via diagnostic thoracocentesis.
Diagnostic Differentials
• Causes of secondary spontaneous pneumothorax
include bullous emphysema, neoplasia, bacterial
pneumonia, pulmonary abscesses, chronic obstructive pulmonary disease, parasitic infections (dirofilariasis, paragonimiasis, and Filaroides osleri),
BOX 2. MATERIALS FOR
CHEST TUBE PLACEMENT
BOX 3. TIPS FOR CHEST TUBE
PLACEMENT
• Sterile instrument pack including a hemostat,
Kelly or Carmalt clamp forceps, a needle holder,
scalpel holder, and suture scissors
• No. 10 or 15 scalpel blade
• extension set
• Three-way stopcock
• Christmas tree adapter
• Syringe (20–60 mL)
• Commercial thoracostomy tubea
—Cat or dog <7 kg: 14–16 Fr
—Dog 7–15 kg: 18–22 Fr
—Dog 16–30 kg: 22–28 Fr
—Dog >30 kg: 28–36 Fr
• Nonabsorbable suture
• Clip the lateral thorax from behind the scapula
to the last rib, and prepare the area using sterile
technique.
• Place the animal in lateral recumbency.
• Have an assistant pull the skin cranially over the
lateral thorax.a
• Approximate the length of tube to be inserted by
holding the chest tube alongside the chest to the
second rib.
• make a small skin incision in the dorsal third of
the lateral thoracic wall at the level of the 7th to
8th ICS (with the skin pulled cranially).
• With a large hemostat, bluntly dissect the
subcutaneous tissue and muscle layers.
• With the Carmalt forceps, bluntly penetrate the
pleura.
• Keeping the Carmalt forceps in place, open the
forceps to allow the tube into the thorax.
• Advance the tube cranioventrally, then remove
the Carmalt forceps.
• Insert the tube to the level of the second rib,
allowing for all tube fenestrations to be within the
thoracic cavity.
• Remove the stylet, and clamp off the tube with the
hemostat.
• As the skin is released over the tube, a subcutaneous
tunnel is created from approximately the 10th–11th
ICS to the 7th–8th ICS.
• Place a purse-string suture in the skin around the
tube and a finger-trap suture pattern around the
tube. One interrupted suture may be placed from
the skin through the periosteum of the rib and
around the tube to secure it in place.
• Connect the Christmas tree adapter, extension
tubing, stopcock, and syringe or, alternatively, the
continuous suction device.
• Thoracic radiographs should be obtained after
placement in order to verify the correct position of
the tube.
aA red rubber catheter can be substituted if a tube made of a
more suitable material is not available; however, patient
reactivity to red rubber catheters can lead to complications.
congenital cysts, migrating foreign bodies, feline
asthma, and pulmonary thromboembolism.
• Traumatic or iatrogenic causes of pneumothorax
should be identified and ruled out through a thorough history and identification of signs of trauma
such as tracheal tears, rib fractures, and pulmonary
contusions.
TREATMENT
RECOMMENDATIONS
Initial Treatment
The primary initial goal is to stabilize the patient until
diagnostic tests can be performed to determine if surgical intervention is indicated.
• Thoracocentesis: Initial stabilization consists of
removal of the free air in the pleural space. $
• It is preferable that all patients receive supplemental oxygen during thoracocentesis. This may be
achieved with mask or flow-by oxygen administration; however, severely compromised or apneic
patients may require intubation.
aIf
no assistant is available, the skin incision should be performed at the 10th to 11th ICS and a subcutaneous tunnel
created cranially to the desired site of penetration (7th to
8th ICS).
— Total IV anesthesia (TIVA) using an opioid/
benzodiazepine combination ± ketamine may be
preferred to inhalant anesthesia for chest tube
placement in severely compromised patients
because TIVA has fewer depressant effects on the
cardiovascular and respiratory systems.
Alternative/Optional
Treatments/Therapy
Tube Thoracostomy
• Thoracocentesis alone may not stabilize the patient
if the bulla involves a bronchus with a diameter
larger than the needle. If needle thoracocentesis is
unsuccessful, tube thoracostomy should be emergently performed (Boxes 2 and 3). $-–$$
• Indications for tube thoracostomy include failure of
needle thoracocentesis, the need for needle thoracocentesis more than twice during a 24-hr period,
or detection of tension pneumothorax.
STANDARDS
of CARE: e m e R g e N C y
— Opioids (good cardiovascular stability, mild
respiratory depression [canine dosages below;
use half dose for feline dosage IV]):
• Hydromorphone: 0.05–0.1 mg/kg IV. $
• Oxymorphone: 0.025–0.1 mg/kg IV. $
• Fentanyl: 2–5 μg/kg IV. $
• morphine: 0.1–0.3 mg/kg IV. $
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ON
THE
NEWS
FRONT
— In humans, the use of underwater seal
devices has achieved statistically better rates
of early chest tube removal and increased
avoidance of pleurodesis compared to
patients treated with traditional management.
An underwater seal device is an airtight
system to maintain subatmospheric
intrapleural pressure. It acts as a one-way
valve through which air is expelled from the
pleural space and prevented from reentering
during the next inspiration.
— Heliox, an inert helium-oxygen mixture
comprising 80% helium and 20% oxygen,
has been shown to be as effective as oxygen
in reducing the degree of experimental
spontaneous pneumothorax. The mechanism
of this reduction is not fully understood but
may be related to denitrogenation.
—Heliox avoids the potential adverse effects
of treatment with pure oxygen.
—The low density and viscosity of heliox
reduce turbulent airflow and increase
laminar airflow, thereby decreasing the
work of breathing.
—Heliox is available as a prehomogenized
mixture. Alternatively, the mixture may
be created by connecting a helium tank
to an established oxygen line through a
y-connector and adjusting both gas flows
to achieve the desired ratio.
— Diazepam/midazolam: 0.1–0.25 mg/kg IV
(good cardiovascular/respiratory stability). $
— Ketamine: 2–4 mg/kg IV (good cardiovascular/
respiratory stability). $
— Double all doses for Im administration.
• Inhalant anesthesia using isoflurane or sevoflurane.
$$–$$$$
— Inhalant anesthetics decrease ventilation in a
dose-dependent manner and possess cardiovascular-depressant properties.
— Positive-pressure ventilation should be avoided
until the tube is in place because it can exacerbate pneumothorax and rupture additional bullae and blebs.
— Patients maintained on inhalant anesthesia for
tube placement should be premedicated with
an opioid (see above for doses) for pain management.
— Local anesthetic blocks for the skin and pleura
should be performed using 2% lidocaine (1–2
mg/kg) or 0.25% bupivacaine (1–2 mg/kg). $
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• Lidocaine may take 5–10 min and bupivacaine 20–30 min for full effect.
• Thoracic exploration and partial or complete lobectomy. $$$–$$$$
— Results of recent studies show that dogs treated
with early surgical intervention have lower
recurrence rates and higher success rates than
dogs maintained with intermittent thoracocentesis or tube thoracostomy.
— The median sternotomy approach is preferred
to lateral thoracotomy because it provides better exposure of the entire pleural cavity and
access to both lungs.
— Lesions have been reported in multiple lung
lobes in 37% of cases and bilaterally in 26% of
cases.
— If the source of the pneumothorax cannot be
visualized, the pleural cavity can be filled with
saline to identify the leak as air bubbles escape.
— Stapling equipment or suture techniques may
be used for partial lobectomy, removal of
peripheral lesions such as bullae or blebs, or
total lobectomy for infiltrative lesions such as
pulmonary neoplasia or abscesses.
— A thoracostomy tube should be placed before
surgically closing the thorax.
Thoracoscopy $$$–$$$$
• This technique has been used diagnostically and
therapeutically for spontaneous pneumothorax in
dogs.
• Thorough exploration of the thorax may require
bilateral thoracoscopic evaluation and pulmonary exclusion. Pulmonary exclusion requires
selective intubation or specially designed endotracheal tubes to ventilate one mainstem
bronchus.
— The inconsistent location of pulmonary lesions
makes careful examination of all parts of all the
lung lobes necessary.
— Thoracoscopic partial lobectomies can be performed to remove ruptured bullae and blebs
and focal areas of diseased lung.
Oxygen Therapy
• Trapped air will be absorbed from the pleural space
over several days to weeks (cost depends on hospital fees). $–$$$$
— Patients with normal vital signs and oxygenation parameters and without significant clinical
signs of pneumothorax may be managed with
oxygen therapy alone.
— If the concentration of inhaled oxygen is
increased and the concentration of inhaled
nitrogen decreased, the partial pressure of nitro-
gen in the capillaries will be reduced, leading to
a greater diffusion gradient and increased speed
of resolution of pneumothorax.
• Success has been reported with medical treatment
of the underlying disease combined with intermittent thoracocentesis, tube thoracostomy, and/or
oxygen therapy in nonsurgical secondary spontaneous pneumothorax caused by pneumonia, dirofilariasis, and paragonimiasis.
CHECKPOINTS
—If the patient is critical and pneumothorax
is suspected based on auscultation and
clinical signs, thoracocentesis should be
performed immediately for both its
diagnostic and therapeutic advantages.
—Intermittent thoracocentesis and thoracostomy
tube placement are ineffective for long-term
therapy.
Supportive Treatment
• Care of the patient after thoracostomy tube placement:
— Secure the chest tube in place and apply a sterile bandage to keep the site clean and covered.
Bandages should be changed at least once
daily using strict aseptic technique.
— An elizabethan collar may be placed on the
patient.
— Patients require 24-hr monitoring of respiratory
rate and effort. The patient should be kept sternal or turned frequently (every 2–4 hrs) to prevent atelectasis of the recumbent lung.
— The tube should be aspirated every 30 min to 4
hr as needed. generally, it is best to aspirate the
tube every 30 min to 1 hr for the first 4 hr, then
once every 4–6 hr.
— The tube may be removed once negative
pressure has been achieved for 12–24 hr.
When the tube is removed, a nonadherent
pad with antibiotic ointment may be pressed
over the exit site. A light bandage is then
placed over the site to allow healing by second intention.
• Continuous suction with a pleural drainage device
should be instituted if the accumulation rate of air
becomes life threatening. $$$–$$$$
— many commercial systems based on the underwater bottle principle are available, but the
three-chambered water seal suction apparatus
is recommended. A suction pressure of 10–15
cm H2O is used.
— Advantages of continuous suction include
allowing sustained lung expansion and better
healing of leaks by pleural adhesion.
— The disadvantages of this method are that the
drained air is not quantifiable and that the
apparatus requires 24-hr monitoring.
• Postoperative pain medications are indicated for
surgical patients while in the hospital and at home.
— Hydromorphone: 0.05–0.2 mg/kg IV q4–6h. $
— Oxymorphone: 0.025–0.1 mg/kg IV q4–6h. $
— Fentanyl CRI: 2–8 μg/kg/hr IV. $
— morphine/lidocaine/ketamine CRI IV (see formula below). $
STANDARDS
of CARE: e m e R g e N C y
—Surgical exploration is recommended for
dogs with spontaneous pneumothorax
without identifiable nonsurgical or diffuse
pulmonary disease.
—Due to lack of a reliable method, pleurodesis
cannot be recommended at this time.
• morphine: 0.1–0.2 mg/kg/hr (may substitute
fentanyl: 2–8 μg/kg/hr).
• Lidocaine: 10–25 μg/kg/min.
• Ketamine: 2–5 μg/kg/min.
— Fentanyl patch. $
• Variable absorption and time to reach analgesic levels.
• Cats and dogs <10 kg: 25 μg/hr.
• Dogs 10–20 kg: 50 μg/hr.
• Dogs 20–30 kg: 75 μg/hr.
• Dogs >30 kg: 100 μg/hr.
— If indicated, these patients should be sent home
with an oral pain medication such as tramadol
at 2–4 mg/kg PO q8–12h or codeine at 1–2
mg/kg PO q6–8h. $
— NSAIDs may be added for multimodal pain
relief if there is no evidence of renal or liver disease. $
• Carprofen: 2.2 mg/kg SC or PO q12h
(approved for dogs only).
• meloxicam: 0.1–0.2 mg/kg SC or PO q24h
(dogs only). Reduced dosage for cats is
0.1–0.2 mg/kg SC/PO on the first day, then
0.05–0.1 mg/kg SC/PO for 3–4 days, then
0.025 mg/kg SC/PO 2 to 3 times weekly.
Injectable is approved for dogs and cats;
however, the oral dose is used off-label in
cats.
• Deracoxib: 3–4 mg/kg PO q24h (approved
for dogs only).
Patient Monitoring
• Patients should be monitored closely for recurrence
of pneumothorax by monitoring respiratory rate and
effort, heart rate, pulse oximetry, and blood pres9
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sure. Respiratory rate and effort should be monitored every 30 min–1 hr for the first 12–24 hr postoperatively.
• Postoperative thoracotomy patients should be managed in a hospital ward with 24-hr nursing care.
• Cage rest for a 24-hr period is recommended.
Home Management
• exercise restriction is recommended in the immediate postoperative period.
• Owners should monitor respiratory rate and effort.
Milestones/Recovery Time Frames
• median duration of hospitalization for dogs treated
with surgery is 6 days; median duration of hospitalization for dogs treated medically is 4 days.
• Postoperative median sternotomy patients are typically very painful and may take several weeks to
completely recover.
Treatment Contraindications
• Before stabilization, exercise caution when administering any medications that may result in apnea or
cardiopulmonary depression (e.g., propofol, acepromazine, medetomidine).
• Inhalant nitrous oxide should be avoided as it may
cause a rapid increase in the volume of the pneumothorax.
PROGNOSIS
• The prognosis depends on the underlying pulmonary disease process.
• The recurrence rate is 3.3% in surgically treated
dogs and 50% in medically managed dogs.
• The mortality rate is 12.1% in surgically treated
dogs and 53% in medically managed dogs.
Favorable Criteria
• Identifiable and resectable focal disease.
• Aggressive medical management and early surgical
intervention.
Unfavorable Criteria
• Tension pneumothorax.
• Pneumothorax associated with disease processes of
poor prognosis (e.g., neoplasia).
• The underlying disease of bullous emphysema has
a guarded prognosis due to its recurrent nature.
• Recurrence of pneumothorax.
RECOMMENDED READING
Au J, Weisman D, Stefanacci J, Palmisano m. Use of computed
tomography for evaluation of lung lesions associated with spon-
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taneous pneumothorax in dogs: 12 cases (1999–2002). JAVMA
2006;228(5):733-737.
Brissot H, Dupre g, Bouvy B, Paquet L. Thoracoscopic treatment of
bullous emphysema in 3 dogs. Vet Surg 2003;32:524-529.
Brockman D, Puerto D. Pneumomediastinum and pneumothorax.
In: Lesley King, ed. Textbook of Respiratory Diseases in Dogs
and Cats. Philadelphia: Saunders; 2004:616-624.
Byers Cg, Romeo K, Johnson A, Campoy L. Helium-oxygen gas-carrier mixture (Heliox): a review of physics and potential applications in veterinary medicine. J Vet Emerg Crit Care 2008;18(6):
586-593.
Cooper e, Syring R, King L. Pneumothorax in cats with a clinical
diagnosis or feline asthma: 5 cases (1990–2000). J Vet Emerg
Crit Care 2003;13(2):95-101.
Lipscomb V, Hardie R, Dubielzig R. Spontaneous pneumothorax
caused by pulmonary blebs and bullae in 12 dogs. JAAHA
2003;39:435-445.
Lisciandro g, Lagutchik m, mann K, et al. evaluation of a thoracic
focused assessment with sonography for trauma (TFAST) protocol
to detect pneumothorax and concurrent thoracic injury in 145
traumatized dogs. J Vet Emerg Crit Care 2008;18(3):258-269.
Puerto D, Brockman D, Lindquist C, Drobatz K. Surgical and nonsurgical management of and selected risk factors for spontaneous pneumothorax in dogs: 64 cases (1986–1999). JAVMA
2002;220(11):1670-1674.
ARTICLE #2 CE TEST
CE
See next page
for instructions.
1. The most common cause of spontaneous pneumothorax is
a. pulmonary abscess.
b. the rupture of bullae or blebs.
c. Filaroides osleri.
d. neoplasia.
e. migrating foreign material.
2. Which statement is false regarding treatment of
spontaneous pneumothorax?
a. Pleurodesis for ruptured bullae has been shown
to result in longer survival times compared with
surgical management.
b. Surgical management results in lower recurrence
and mortality than medical management.
c. Needle thoracocentesis is a quick, easy initial
step to stabilize a spontaneous pneumothorax
patient.
d. median sternotomy is recommended over lateral
thoracotomy.
e. CT is superior to radiography for determining the
location and number of pulmonary lesions.
3. Typical radiographic findings with spontaneous
pneumothorax include
a. loss of the cardiac silhouette due to pleural effusion.
b. enlarged heart and collapsing trachea.
c. retraction of lung margins from the chest wall.
d. fractured ribs and pulmonary contusions.
e. an alveolar pattern in the right middle lung lobe.
4. Which statement is false regarding stabilization
and treatment of dogs with spontaneous pneumothorax?
a. If pneumothorax is suspected based on the physical examination and the patient is stable, chest
radiography should be performed to confirm the
diagnosis before instituting treatment.
b. Propofol, acepromazine, and medetomidine
should be avoided as sedative choices.
c. Intermittent thoracocentesis is superior to surgical management.
d. Postoperative thoracostomy tubes may be
removed once negative pressure has been
achieved consistently for 12–24 hrs.
e. Owners should be instructed to monitor their
pet’s respiratory rate and effort at home.
5. Which statement is true regarding heliox therapy?
a. Heliox is a mixture of 80% oxygen and 20%
helium gas.
b. This therapy has been shown to be superior to
treatment with 100% oxygen.
c. The high viscosity of heliox increases laminar
airflow, thereby decreasing work of breathing.
d. The low density of heliox reduces turbulent airflow, thereby decreasing work of breathing.
e. Heliox has a noxious odor, allowing easy detection of leaks.
PERIANAL FISTULA
(continued from page 4)
Mathews KA, Sukhiani HRS. Randomized controlled trial of
cyclosporine for treatment of perianal fistulas in dogs. JAVMA
1997;211(10):1249-1253.
Milner HR. The role of surgery in the management of canine anal
furunculosis. A review of the literature and a retrospective
evaluation of treatment by surgical resection in 51 dogs. N Z
Vet J 2006;54(1):1-9.
Misseghers BS, Binnington AG, Mathews KA. Clinical observations
of the treatment of canine perianal fistulas with topical
tacrolimus in 10 dogs. Can Vet J 2000;41(8):623-627.
O’Neill T, Edwards GA, Holloway S. Efficacy of combined cyclosporine A and ketoconazole treatment of anal furunculosis. J Small
Anim Pract 2004;45(5):238-243.
Patricelli AJ, Hardie RJ, McAnulty JF. Cyclosporine and ketoconazole for the treatment of perianal fistulas in dogs. JAVMA
2002;220(7):1009-1016.
Robson D. Review of the pharmacokinetics, interactions and
adverse reactions of cyclosporine in people, dogs and cats. Vet
Rec 2003;152(24):739-748.
Tisdall PLC, Hunt GB, Beck JA, Malik R. Management of perianal
fistulae in five dogs using azathioprine and metronidazole
prior to surgery. Aust Vet J 1999;77(6):374-378.
Zoran DL. Rectoanal disease. In: Ettinger SJ, Feldman EC, eds.
Textbook of Veterinary Internal Medicine. 6th ed. St Louis:
Elsevier Saunders; 2005:1408-1420.
ARTICLE #1 CE TEST
CE
See box below
for instructions.
1. German shepherds may be more predisposed to
perianal fistulas because their perianal tissue has
a. a decreased density of hair follicles.
b. an increased density of apocrine glands.
c. an increased density of sebaceous glands.
d. decreased subcutaneous vascular beds.
2. Approximately _____ of dogs with perianal fistulas
have histopathologic evidence of colitis.
a. 10%
b. 50%
c. 75%
d. 90%
3. Diagnostic differentials for perianal fistula include
a. Pythium spp infection.
c. perianal tumors.
b. anal sac abscesses.
d. all of the above
4. Which surgical procedure has not been used to treat
or manage perianal fistulas with some success?
a. subtotal colectomy
b. complete tail amputation
c. radical excision
d. debridement with fulguration
5. Which drug can be used to decrease the dosage of
cyclosporine?
a. itraconazole
c. griseofulvin
b. fluconazole
d. ketoconazole
The Auburn University College of Veterinary Medicine approves these articles for 1 contact hour each of continuing education credit. Those who wish to apply this credit to fulfill state relicensure requirements should consult their respective
state authorities regarding applicability. Subscribers may take individual CE tests online and get real-time scores free of
charge at SOCNewsletter.com.
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