A Eupnea: normal rate and rhythm B Tachypnea: increased respiratory rate; caused by fever, hypoxia, hypercapnea, pneumonia, or lesions of the CNS respiratory centers C Bradypnea: slow but regular respirations; caused by sleep, anesthesia, opioids, hypothermia, neoplasia, or respiratory decompensation D Apnea: absence of respiration; may be periodic; caused by drug depression, muscle paralysis, overventilation, obstruction, shock, increased intracranial pressure, or surgical manipulation of vagus and splanchnic nerves E Hyperpnea: large respirations (increased tidal volume); rate normal; caused by excitement, pain, surgical stimulation, hypoxia, hypercarbia, heat, or cold F Cheyne-Stokes respiration: respirations become faster and larger, then slower, followed by an apneic pause; caused by increased intracranial pressure from head trauma or neoplasia, meningitis, renal failure, severe hypoxia, anesthetic drug overdose, or high altitude G Biot’s respiration: respirations that are faster and deeper than normal, with abrupt pauses between them; each breath has approximately the same tidal volume; caused by anesthesia in normal, athletic horses and greyhounds; spinal meningitis; or drugs that cause generalized CNS depression H Kussmaul’s respiration: regular and deep respirations without pauses; animal’s breathing usually sounds labored, with breaths that resemble sighs; caused by renal failure, metabolic acidosis, or diabetic ketoacidosis I Apneustic: prolonged gasping inspiration, followed by extremely short, inefficient expirations; caused by high doses of drugs (e.g., ketamine in cats and horses or excessive doses of guaifenesin in horses) or lesions in the pons and thalamus I Definition: a respiratory emergency is the inability to maintain adequate gas exchange (oxygen [O2]; carbon dioxide [CO2]) such that tissue oxygenation and acid-base status become compromised A Potential causes of impaired gas exchange: 1. Hypoventilation caused by preanesthetic or anesthetic drugs 2. Improper placement (e.g., esophageal) of the endotracheal tube 3. Parenchymal pulmonary disease and pulmonary edema (diffusion impairment) 4. Pleural cavity disease (pneumothorax, fractured ribs) a. Foreign body or material in trachea c. Small or obstructed endotracheal tubes. Do not overinflate the cuff. d. Restricted chest wall movement; improper physical restraint or positioning for surgery, improper bandaging e. Nasal obstruction or edema (brachiocephalic breeds) 7. Closed pressure release (“pop-off”) valve III Species, age, size, and concurrent lung pathology determine respiratory frequency, rate of lung inflation, inflation pressure, and tidal volume to be delivered; larger animals generally require slower inflation rates, lower frequencies of breathing, and larger volumes. Note: Three to 4 minutes of preoxygenation with 100% O2 can markedly prolong the time to hemoglobin desaturation, hypoxemia, and cyanosis. A Pneumothorax should be corrected immediately to ensure adequate lung expansion and reduce the potential for developing tension pneumothorax IV Treating hypoventilation and apnea A If the animal is taking small-volume breaths or is apneic, establish an airway and institute artificial ventilation with room air or O2; O2 is preferred B Control breathing rate if apneic; assist ventilation if breathing 2. Inspiratory time: 1 to 3 seconds, depending on size of the animal 3. Maintain proper inspiratory time /expiratory time ratio of 1 : 2, 1 : 3, or 1 : 4 4. Inflate lungs to 15 to 20 cm H2O if chest is closed (up to 20 to 30 cm H2O in large animals). Note: Higher pressures may be required in animals that have fluid or masses in the chest or that have restrictive lung disease. 5. Inflate lungs to 20 to 30 cm H2O if chest is open or atelectasis of lungs has occurred (up to 40 cm H2O in large animals) 6. Tidal volume (volume of air inspired or expired in a single normal breath) V Assist or control ventilation until the animal can maintain adequate tidal breathing and gas (O2; CO2) exchange, normal mucous membrane color, and hemoglobin saturation (SpO2; see monitoring) I Slow or rapid small volume breaths, apnea or dyspnea II Increased frequency of breathing; respiratory rate and effort are generally increased in animals with respiratory distress or disease III Coughing, stridor, or sonorous breathing sounds are associated with airway obstruction. Animals may vomit. IV Cyanosis: bluish discoloration of the mucous membranes A Cyanosis may be absent in severely anemic animals (hemoglobin less than 5 g/dL); animals may become pale gray I Partial airway obstruction may be associated with respiratory disease or obstruction/kinking of the endotracheal tube II Conditions that predispose animals to airway obstruction B Edema of the nasal turbinates C Elongated or displaced soft palate D Collapsing arytenoid cartilages E Everting laryngeal ventricles 1. Middle-aged to older, obese, toy-breed dogs, especially miniature poodles, Yorkshire terriers, and Chihuahuas G Laryngeal paresis or paralysis (“Lar-Par”) 2. Congenital, especially in Bouvier des Flandres, bull terriers, and Siberian huskies 3. Acquired in giant-breed dogs, especially in Labrador and golden retrievers III Other causes of airway obstruction B Nasal disease (e.g., tumor, fungus, parasites) C Mucus or blood in airway or endotracheal tube D Orotracheal device or anesthetic circuit obstruction due to improper setup or kinking 1. Noisy, stridorous, or labored breathing (snoring) 2. Choking, retching, and vomiting 3. Pawing or clawing at face and throat
Respiratory Emergencies
Overview
General Considerations
Clinical Signs of Respiratory Distress
Airway Obstruction
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