Respiratory Flashcards
when can respiratory complications happen? (5)
▪ Sedation
▪ Induction/Intubation
▪ Maintenance
▪ Recovery
▪ Post-anesthetic period
6 things to remember/consider if respiratory complications happen
▪ Stay calm
▪ Identify the problem ASAP – Adequate monitoring
▪ Realize the significance of problem
▪ Understand the potential causes
▪ Understand the emergency of the situation and consequences
▪ Know the treatment – have the tools to treat
what are some situations that can increase the chance of respiratory problems? (5)
o Species, breed
o Pre-existing condition or disease
o Type of surgery/procedure
o Drugs used
o Positioning
what are some examples of respiratory complications (6)
▪ Hypoxemia
▪ Apnea
▪ Hypoventilation
▪ Hyperventilation
▪ Airway obstruction
▪ Tension pneumothorax
what is considered relative (mild) hypoxemia
PaO2 < 80 mmHg or SpO2 < 95%
what is considered moderate and severe absolute hypoxemia
▪ Moderate = PaO2 < 60 mmHg or SpO2 < 90%
▪ Severe = PaO2 < 40-45 mmHg or SpO2 < 80%
when does cyanosis occur? what makes it lower?
▪ Cyanosis: if 5.0 g/dL of deoxyhemoglobin or more
▪ SpO2 of < 85% if Hb is normal
▪ Lower if patient is anemic
what do you need to measure PaO2
To measure PaO2 you need an arterial sample (ideal if problems are
anticipated)
what are some causes of hypoxemia (5)
▪ V/Q Mismatch: Atelectasis, pulmonary edema, pulmonary contusions, thromboembolism, asthma…
▪ R-L shunt: intra-cardiac or intra-pulmonary
▪ Diffusion impairment: pneumonia, interstitial lung disease…
▪ Hypoventilation (severe)
▪ Decreased FiO2
when is SpO2 of limited value?
SpO2 limited value when FiO2=1
what is the treatment for hypoxemia? (6)
▪ Treat the underlying problem
- Increase FiO2, check your O2 source
- Lung re-expansion, change in position (sternal)
- Bronchodilators
- Support and optimize ventilation (IPPV or manual)
- Diuretics
- Surgical correction if needed (PDA, bullae, lung consolidation…)
what two times should you pay special attention for respiratory complications
- During induction (pre-oxygenate)
- During recovery (switching from 100% to room air)
▪ Some patients may need ventilator support post- anesthetic, time, and medical management
what is apnea?
> 1 min without spontaneous breathing
time to desaturation for normal room air vs pre-oxygenation vs IPPV on 100%
-Normal dogs room air: 1.16 min
-Pre-oxigenation for 3 min: 5 min
-IPPV on 100%: 8-13 min
what are some causes of apnea? (6)
- Commonly after induction: Propofol, Alfaxalone, thiopental… High doses, rapid administration
- Excessive depth (1.5-3 X MAC) or additional drug administration (opioids)
- Hypocarbia
- Excessive work to ventilate: airway obstruction
- Inability to ventilate: Neurological disorders, chest open, neuromuscular blockers, tension
pneumothorax… - Cardiopulmonary arrest (Check the heart)!
what is alveolar hypoventilation?
Alveolar hypoventilation is defined as insufficient ventilation leading to hypercapnia (PaCO2 >50-55mmHg)
ETCO2: 3-5 mmHg < PaCO2
what is alveolar hypoventilation caused by
Caused by decrease in tidal volume, respiratory rate, increase dead space, or a combination
physiological effects of hypercapnea (6)
▪ Stimulation of respiratory drive
▪ Respiratory acidosis
▪ Increase cerebral blood flow
▪ CNS depression
▪ Sympathetic stimulation
▪ Hypoxemia
what happens to HR and BP when there is sympathetic stimulation and catecholamine release
Increase in HR and BP
what can severe hypercapnea lead to?
hypoxemia
what are some pre-existing conditions that can lead to hypercapnea during anesthesia (5)
- Obesity, increased abdominal pressure
- Neurologic disorders (CNS or PNS)
- Pathologies of thoracic wall or lungs: Pneumothorax, pleural disorder, thoracic mass, trauma…
- Age (neonates and geriatrics)
- Hypothermia
what two things can lead to increased CO2 production
- Hyperthermia: hypermetabolic state
- Systemic absorption during laparoscopic procedures
what are some equipment related causes of hypercapnea (3)
- Increased mechanical dead space: excessive tubing length, adaptors…
- Increased work of breathing: ET tube too small
- CO2 rebreathing:
- Reduced oxygen flow rate: Non rebreathing systems (Bain)
- Exhausted soda lime
- Unidirectional valves not moving properly
what is hyperventilation characterized by and what can it lead to
▪ Characterized by increased respiratory rate
▪ It can lead to hypocapnia and respiratory alkalosis
treatment for hypercapnea (7)
▪ Identify the underlying cause!
▪ Be aware of pre-existing conditions
▪ Measure ETCO2 and/or PaCO2
▪ Check the patient: Drugs administered and doses (reversal?), Check anesthetic depth
▪ Correct body temperature
▪ Check the equipment
▪ Support ventilation as necessary
what are 4 causes of hyperventilation
- Light plane of anesthesia and/or nociception
- Hypercapnia (see prior section)
- Hypoxemia
- Metabolic acidosis (Respiratory compensation)
causes of airway obstruction (6)
▪ Anatomy: brachycephalic breeds
▪ Underlying disease: upper or lower airway
▪ Airway swelling: surgery, trauma
▪ Aspiration of foreign material
▪ External pressure: bandage position
▪ Equipment problems or errors
partial vs complete airway obstruction? when can it happen?
▪ Partial obstruction: Increased work of breathing
▪ Total obstruction: Inability to move air
▪ Can happen at premedication, induction, maintenance, or recovery
what does paradoxic breathing look like
- Thoracic wall sucks inward
- Abdominal wall expands
- Open mouth breathing, nostril flare, neck flexed, stridor
how do you diagnose airway obstruction (6)
▪ Paradoxic breathing
▪ Prolonged inspiratory time
▪ Hypoxemia and/or cyanosis
▪ Rebreathing bag is not moving
▪ Capnograph wave abnormal or disappears
▪ High pressures generated when trying to ventilate
components of brachycephalic syndrome (4)
- Elongated soft palate
- Everted saccules
- Hypoplastic trachea
- Stenotic nares
three presentations of upper airway disease
▪ Laryngeal paralysis
▪ Laryngeal hemiplegia
▪ Laryngospasm
three presentations of lower airway disease
▪ Tracheal mass
▪ Tracheal stenosis
▪ Tracheal collapse
what can cause bronchospasm (4)
asthma, reactive airway, anaphylaxis,
bronchitis
how do you treat obstruction when the animal is intubated?
treat with bronchodilators, epinephrine, antihistamines
causes of airway inflammation (3)
- Respiratory distress/effort
- Surgery
- Trauma
treatment of airway inflammation
Treatment (before extubation):
- Corticosteroids
- Local vasoconstrictors (Phenylephrine, epinephrine)
- Dextrose 50%
what are some examples of equipment probles that can lead to respiratory issues (4)
▪ Kinked, twisted ET tubes
▪ Kinked breathing circuit
▪ Mucus/blood other ET tube obstruction
▪ Pop-off closed = tension pneumothorax
how to deal with airway obstruction intra-operatively
- Check patient and equipment quickly
- SPO2, ETCO2, BP, HR
- Manually ventilate to assess
- Suction tube, change if necessary
how to deal with airway obstruction at recovery
- Extend head, pull out tongue
- Re-intubate - tracheostomy
how does tension pneumothorax present
▪ Increase in respiratory effort
▪ Lack of lung sounds
▪ Resistance to ventilation (high Peak Inspiratory Pressure)
▪ Eventually disappearance of capnograph wave
▪ Followed by cardiac arrest
what is the treatment of tension pneumothorax
- Tap the chest
- Chest tube
- Continuous suction
what is tension pneumothorax
Life threatening emergency! Accumulation of air under pressure,
compressing the lungs and decreasing venous return
