2 respiratory support Flashcards

1
Q

General methods / options for respiratory support?

A
  • o2 therapy
  • positive pressure ventilation
  • humidification of inspired gases
  • aerosol therapy
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2
Q

What is the primary indication for o2 therapy?

A

hypoxia

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3
Q

What are some conditions that may lead to hypoxia?

A
  • inadequate inspired o2
  • impaired pulmonary function
  • ineffective o2 transport
  • inc o2 demand [NOT met by normal o2 delivery]
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4
Q

What are objective measures to determining the need for o2 therapy in a patient?
And subjective signs?

A
  • arterial blood gas (PaO2
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5
Q

What are some methods for o2 administration?

A
  • face mask/flow by/nasal prongs
  • baggie, e collar, hood
  • o2 cage, chamber, tent
  • intranasal catheter
  • intratracheal catheter
  • nasotracheal catheter
  • endotracheal tube
  • tracheostomy tube
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6
Q

When might an oxygen tent be employed?

A
  • patient is sedated or depressed
  • short term use
  • often immediately post op
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7
Q

Some benefits to intranasal o2 supplementation?

a down side?

A
  • have more control over % o2 animal is getting
  • designed for more extended care
  • more secure
  • anchor tubes so more invasive
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8
Q

When inserting a intranasal tube, what is landmark on face of animal to measuring the length of the tube?

What is the basic procedure?

A
  • medial canthus of the eye (or level of upper 4th pre molar)
  • deaden area, measure tube, mark tube, puncture lateral canthus of nose with needle, put suture through needle, tie a square know, INSERT TUBE INTO VENTRAL MEATUS, thread straight, surgeon’s knot around top then secure suture to top of patient’s head
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9
Q

general procedure to intratracheal o2 supplementation?

A
  • clip and prep neck
  • caution to NOT introduce environmental pathogens
  • puncture directly into trachea w/o filtration of nose first
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10
Q

B/c the filtration of the nose is lost with intratracheal o2 supplementation, what special consideration should be made?

A

flow rates slower than when tube goes into nose

also a softer catheter is used

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11
Q

when comparing intranasal vs intratracheal o2 administration, which yields more o2 delivery?

A

intratracheal

direct delivery into the trachea is same o2 flow rate but 1.5x more o2 reaches lungs - better effects

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12
Q

What is the main guideline for o2 administration?

A
  • flow rates
  • resultant FiO2 and PaO2
  • the clinical patient’s physiological state may dictate higher or lower flow rates
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13
Q

What is the upper limit to PaO2 typically?

What situation is an exception?

A
  • above 100 mmHg usually has limited benefit b/c SaO2 is 97%+ [Hb is saturated at this point}
  • except in SIRS [patient needs all the help it can get and may rely on o2 dissolved in blood, whereas most patients only benefit from o2 on Hb]
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14
Q

Why is trachea delivery of o2 more efficient method?

A
  • trachea serves as oxygen rich reservoir

- lower flow rates are more economical

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15
Q

Factors to influence choice btwn IN (nasal) or IT (tracheal) administration of o2?

A
  • clipping and aseptic prep req for IT placement
  • nasal trauma or dz may preclude use of IN tube
  • upper airway obstruction must be INCOMPLETE to use IT o2 b/c obstruction may px escape of excessive IT flow
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16
Q

prolonged levels of what % o2 can lead to oxygen toxicity?

A

50-60%

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17
Q

How to monitor o2 therapy?

A
  • clin signs: resp rate, character of resp, mucous mem color
  • pulse oximetry
  • arterial blood gas
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18
Q

describe function of pulse oximeter

A
  • commonly used
  • probe on tongue in anesthetized patient
  • one side has diode that emits red and infrared light and other side has detector - light is sent through tissues and detected on the other side
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19
Q

What does the value from a pulse oximeter tell you?

A
  • % of oxygenated Hb in Aa

- equal to SaO2 in arterial blood gas

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20
Q

Guidelines to weaning a patient off oxygen therapy:

A
  • monitor clin signs
  • monitor SpO2
  • serial arterial blood gas
  • trials off 02: re institute o2 administration as indicated and see if clin signs come back
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21
Q

what clinical signs indicate re institution of o2 therapy?

A
  • clin signs of hypoxia
  • inc resp rate
  • abnormal respiratory rate
  • pale, cyanotic, or “muddy” mucous membranes
  • Sp02 (SaO2) less than 96% [ b/c at 90%, it drops of VERY fast ]
  • PaO2 less than 80 mmHg
22
Q

complications with o2 therapy?

A
  • apnea in patients w severe respiratory dz: loss of hypoxic ventilatory drive
  • intra pulmonary shunting
  • o2 toxicity
23
Q

Clinical manifestations of o2 toxicity?

A
  • pulm edema
  • atelectasis
  • consolidation
  • congestion
  • hemorrhage
  • fibrosis
  • functional impairment
24
Q

What is tricky about clinical manifestations of o2 therapy?

A

they are the same signs that would trigger the initiation of oxygen therapy

use judgement and knowledge of patient history to decide

25
Q

oxygen toxicity pathogenesis?

A
  • cytotoxic peroxides and free radicals
  • result of excessive PaO2, but described in terms of FiO2:

microscopic changes and clin signs after 24 hours of 100% FiO2
death after 2-3 days of 100% FiO2

26
Q

what level of FiO2 is apparently safe for long term o2 delivery?

A

50%

27
Q

Indications for positive pressure ventilation?

A
  • ventilatory failure: PaCo2 > 55mmHg
  • failure of o2 therapy to reverse hypoxia
  • adjunctive Tx for intracranial hypertension
28
Q

Considerations with positive pressure ventilation in situations of intracranial hypertension cases / concern?

A
  • physiologically, high PaCo2 causes vasculature of cerebrum to dilate, allowing more blood into cranial vault
  • but space is limited in cranial vault
  • ventilate to bring down PaCo2 and constrict vessels to control pressure necrosis
  • BUT do not ventilate too much or the vessels constrict too much and not enough blood can get into cranial vault
29
Q

Techniques of positive pressure ventilation?

A
  • manual: anesthesia machine bag and ambu bag

- mechanical: controlled vs assissted OR pressure vs volume cycled

30
Q

What is PEEP (positive end expiratory pressure) and CPAP (continuous positive airway pressure) used for?

A
  • to treat alveolar collapse: help alveoli stay open longer to allow more time for gas exchange to occur
  • do dec the work of breathing
  • also helps maintain a more consistent flow
31
Q

What are typical PEEP or CPAP settings to maintain PaO2 or Spo2 at acceptable levels?

A

5-10 cm H20

32
Q

When is positive pressure ventilation and PEEP used?

A
  • when o2 therapy fails - 100% inspired o2 fails to achieve normoxia
  • greater than 50% inspired o2 is required to maintain normoxia, putting the patient at risk for o2 toxicity
33
Q

What is high frequency ventilation?

A
  • high respiratory rate and low tidal volume

- works by diffusion of gases along concentration gradient

34
Q

An advantage to high frequency ventilation?

A
  • low mean airway pressure

- can be used in presence of tracheal disruption

35
Q

when/how to wean patient from ventilatory support?

A
  • begin when animal is stable on the ventilator
  • gradual reduction in minute ventilation to allow PaCo2 in inc enough to stimulate spontaneous ventilation
  • monitor blood gases, SpO2, ETCO2 and respiratory pattern
36
Q

T/F: alveolar air is normally 100% humidified at body temperaturs

A

TRUE

37
Q

What are the effects of dry medical gases?

A
  • inc humidification requirement
  • inc vaporization leading to cooling of liquid surfaces and patient heat loss
  • mucosal drying
38
Q

Effects of mucosal drying?

A
  • inc viscosity of secretions
  • impaired mucociliary transport
  • retention of tenacious secretions
  • mucosal inflammation and degeneration
  • small airway closure, atelectasis and inc shunting
  • dec residual capacity
  • dec pulmonary compliance
  • inc risk of infection
39
Q

What types of humidifiers are there?

A
  • bubble humidifiers
  • heated bubble humidifier
  • humidity exchange filters
  • nebulizers
40
Q

What is an aerosol?

A

a fine suspension of liquid droplets in a carrier gas

41
Q

What is aerosol therapy used for?

A

Delivery of substances to respiratory surfaces to:

  • px desiccation (water)
  • loosen secretions and stim coughing (saline)
  • treat resp dz (drugs)
42
Q

What factors affect aerosol deposition into patients airways?

A
  • particle size: smaller particles deposit in more peripheral (deeper) airways
  • rate and depth of breathing
43
Q

Where does slow/deep breathing deposit aerosol particles?

And rapid/shallow breathing?

A

slow/deep -> peripheral airways

rapid/shallow -> upper airways

44
Q

types of nebulizers?

purpose?

A

jet
babbington
ultrasonic

to break liquid into smaller particles

45
Q

how does a jet nebulizer work?

A

stream of gas over immmersed capillary tube

46
Q

how does a babbington nebulizer work?

A

stream of gas from sphere or like surface onto which fluid is dropped

47
Q

how does an untrasonic nebulizer work?

A
  • piezoelectric crystal

- oscillations of reservoir cause particles to eject from liquid

48
Q

methods of aerosol administration?

A
  • mask, enclosure, breathing circuit
  • 15-20 mins every 4-8 hours
  • maintain patient hydration
  • thoracic physiotherapy (coupage)
  • bronchodilators
  • sterile delivery system
49
Q

T/F: aerosol therapy can be used indefinitely and long term for a patient

A

FALSE

limited to 15-20 mins q 4-8 hours
to prevent over hydration

50
Q

what is the purpose of thoracic physiotherapy? often used with aerosol therapy

A

to help loosen respiratory secretions

coupage

51
Q

why is bronchodilator therapy often used with aerosol therapy?

A

to facilitate particle delivery

52
Q

what drugs can be delivered via nebulization?

A
  • abx: aminogylcosides

- bronchodilators: aminophylline and beta 2 agonists