Page 406 - Clinical Small Animal Internal Medicine

374 Section 5 Critical Care Medicine

Altered breath sounds can also herald respiratory dis-
Box 38.1 Categories of signs associated
VetBooks.ir with respiratory distress in dogs and cats tress in small animal patients and may also aid in the
determination of the underlying cause. Breath sounds

● Abnormal sounds may be altered in their distribution, their volume (i.e.,
loudness), and their character. Diminished breath sounds
⚪ Heard without a stethoscope in the nondependent lung fields may indicate accumula-
– Stertor tion of gas in the pleural space, whereas the same finding
– Stridor in the dependent lung regions suggests pleural fluid
⚪ Heard with a stethoscope accumulation or nonventilated lung (or both). Focal
– Diminished breath sounds absence of breath sounds may indicate that one or more
Regional lung lobes are obstructed, consolidated, collapsed,
Focal
– Adventitious sounds torsed, infiltrated, or compressed by an intrathoracic
mass lesion. In addition, adventitious sounds (crackles,
Crackles wheezes, rhonchi) may indicate lower airway and pul-
Wheezes monary parenchymal pathology. Crackles are explosive,
Rhonchi
– Borborygmus discontinuous, nonmusical sounds generated by small
Changes in position/posture/orientation airways abruptly opening. They may be fine or harsh in
● character. While often heard on inspiration (opening
⚪ Orthopnea during expansion), they may also be present during
⚪ Trepopnea exhalation in some settings. Wheezes are higher pitched,
⚪ Neck extension musical, and of longer duration than crackles. They are
⚪ Upright stance (flexed pelvic limbs, extended often the result of diffuse lower airway narrowing.
thoracic limbs) Rhonchi are similar to wheezes but substantially lower in
– Sternal recumbency (Sphinx pose) pitch. Abnormal sounds that might be ausculted over the
⚪ Abducted elbows thorax also include borborygmus, which may indicate a
Reflex compensatory changes due to hypoxemia
● compromise of the diaphragm with displacement of
and hypercapnia intestinal viscera into the thoracic cavity.
⚪ Tachypnea Changes in body position/posture, orientation of the
⚪ Tachycardia head and limbs, respiratory rate, and the magnitude of
⚪ Hyperpnea inspiratory excursions all may indicate respiratory sys-
Signs associated with reduced/altered gas flow
● tem compromise. Patients in respiratory distress often
velocities assume an upright posture with the pelvic limbs flexed
⚪ Phase prolongation and the thoracic limbs extended. This posture allows the
– Inspiration weight of the abdominal contents to rest on the pelvis
– Exhalation rather than the diaphragm and reduces the work of
– Both breathing. In cats, a more typical posture is to sit propped
⚪ Inability to vocalize in sternal recumbency (sphinx pose). Patients that
Adaptive responses which reduce respiratory system
● exhibit greater respiratory distress when in recumbency
resistance are termed orthopneic and this may manifest as a reluc-
⚪ Open‐mouth breathing tance to lie down or be restrained. The head is often held
– Retracted commissures of the lips in dorsoflexion with the neck extended. This position
⚪ Nares flaring reduces the work of breathing by straightening the tra-
⚪ Neck extension chea and minimizes narrowing. Moreover, by fixing the
Signs secondary to marked hypoxemia
● head position in this way, accessory respiratory muscles
⚪ Cyanosis (e.g., serratus ventralis muscle) can be utilized to pro-
⚪ Obtundation mote expansion of the cranial thorax. Elbow abduction
Abnormal or excessive abdominal motion
● and fixing the position of the forelimbs allows for the
⚪ Passive abdominal motion due to hyperpnea recruitment of other accessory respiratory muscles and
⚪ Active expiratory abdominal muscle contraction reduces the impact of the weight of these limbs on chest
⚪ Paradoxical motion expansion. Respiratory compromise that is more severe
Signs of the sensation of dyspnea
● in one lateral recumbency than the opposite is termed
⚪ Obtundation trepopnea and often is due to asymmetric pulmonary
⚪ “Anxious” expression parenchymal disease.
⚪ Dilated pupils Increases in respiratory rate are often the earliest sign
⚪ Poorly tolerant of restraint/fractious of respiratory system compromise. Tachypnea at rest
⚪ Not eating, drinking, sleeping, and/or grooming
may frequently precede more overt signs in patients with