Respiratory Flashcards by Kendra Broadfoot

when can respiratory complications happen? (5)

▪ Sedation
▪ Induction/Intubation
▪ Maintenance
▪ Recovery
▪ Post-anesthetic period

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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

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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

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what are some examples of respiratory complications (6)

▪ Hypoxemia
▪ Apnea
▪ Hypoventilation
▪ Hyperventilation
▪ Airway obstruction
▪ Tension pneumothorax

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what is considered relative (mild) hypoxemia

PaO2 < 80 mmHg or SpO2 < 95%

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what is considered moderate and severe absolute hypoxemia

▪ Moderate = PaO2 < 60 mmHg or SpO2 < 90%
▪ Severe = PaO2 < 40-45 mmHg or SpO2 < 80%

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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

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what do you need to measure PaO2

To measure PaO2 you need an arterial sample (ideal if problems are
anticipated)

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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

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when is SpO2 of limited value?

SpO2 limited value when FiO2=1

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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…)

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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

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what is apnea?

> 1 min without spontaneous breathing

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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

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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)!

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what is alveolar hypoventilation?

Alveolar hypoventilation is defined as insufficient ventilation leading to hypercapnia (PaCO2 >50-55mmHg)

ETCO2: 3-5 mmHg < PaCO2

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what is alveolar hypoventilation caused by

Caused by decrease in tidal volume, respiratory rate, increase dead space, or a combination

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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

1. Light plane of anesthesia and/or nociception 2. Hypercapnia (see prior section) 3. Hypoxemia 4. 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)

1. Elongated soft palate 2. Everted saccules 3. Hypoplastic trachea 4. 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