Resp Therapy Equipment

Question 1

What are the two types of pulse oximetry?

Answer 1

transmission- light passes through tissue to the sensor

reflectance- sensor and source are side by side

Question 2

How does pulse oximetry work?

Answer 2

Based on the Beer-lambert law (concentration of absorbing substance in a solution is related to the intensity of light transmitted through that solution)

• 2 diodes emit alternating light wavelengths (red light which is absorbed by deoxygenated blood and infrared light which is absorbed by oxygenated blood)
• ratio of absorption is measured and the O2 saturation of hb is derived

Question 3

Factors that affect pulse ox results

Answer 3

• dark skin pigment
• nail polish
• acrylic nail
• motion
• ambient or excessive light
• hypoperfusion (may overestimate)
• hypoxia (less reliable below 80%)
• dyshemoglobinemias (COHb absorbs light in the red wavelength similar to oxyhemoglobin, falsely elevated)
• methemoglobin (Fe3+ vs normal Fe2+, absorbs red and infrared light)
• IV dyes

Question 4

Peak Flow Meters
Indications
what is it

Answer 4

Indications

• asthma
• some pts with COPD who have a component of reactive airway disease

What is it

• an objective measurement of the severity of airway obstruction
• uses best out of 3 measurements
• may help identify triggers

Question 5

Metered dose inhaler

-recommdations for use

Answer 5

recommdations for use

• if on multiple inhalers, administer bronchdilator first
• recommend use of a spacer

Question 6

Why use a spacer?

Answer 6

• improve coordination between delivery of the medication from the inhaler and breathing it into the bronchial tubes
• reduce the amount of medication that settles in the mouth and throat

Question 7

Types of nebulizers

Answer 7

hand held
hand held with mask
blow by
home neb unit
compact neb

Question 8

Goals of oxygen therapy

Answer 8

• improve oxygenation

- long term O2 therapy in COPD if needed improves survival, quality of life and decreases hospitalizations

Question 9

O2 delivery systems

Answer 9

nasal cannula
simple face mask
venturi mask
bag-valve mask
bi-PAP or CPAP

Question 10

What are the methods used to deliver home oxygen?

Answer 10

• compressed O2 (tanks)
• liquid O2
• O2 concentrators

*all inhaled through mask or cannula

Question 11

A nasal cannula provides 6L of O2.

What percent oxygen does nasal cannula provide?

Answer 11

6L=44% oxygen

Question 12

How much oxygen does 1L/min flow rate provide? what is the rate of increase?

Answer 12

1 L/min=21-24%

-increasing the O2 flow rate by 1 L/min equates to an increase of about 4% FIO2

2 L/min= 25-28%
3=29-32%
4=33-36%
5=37-40%

Question 13

How much O2 does a simple face mask provide?

Answer 13

40-60% (5-10L)

*minimum flow of 5L/min needed

Question 14

What is a venturi mask? Who is it good for?

Answer 14

• mask that accurately controls the proportions of inspired oxygen
• good for patients who retain CO2 and pts who have moderate to severe hypoxemia

Question 15

How much O2 does a non-rebreather mask provide?
How much is required?
When to use

Answer 15

Provides up to 90% O2

Need flow rates of 8-10 L/min

Used for seriously ill, responsive and spontaneously breathing who require high O2 content. Also used to avoid tracheal intubation if acute intervention produced a rapid change.

Question 16

Bag valve mask/ambu bag
what is it?
disadvantages

Answer 16

one way valve mask/bag with an O2 for supplemental O2

disadvantages

• mask must be sealed tightly over mouth and nose
• need to coordinate breaths with any spontaneous respiratory effort

Question 17

Oxygen Toxicity
what is it?
possible adverse effects

Answer 17

What is it?

• parenchymal lung injury due to supplemental O2
• thought to be secondary to the production of oxygen free radicals that result in tissue destruction

Possible adverse effects

• absorptive atelectasis (washout of alveolar N2 and atelectasis may occur if O2 diffuses out of the capillaries faster than entering
• extrapulmonary toxicity (seizures, retinopathy, coronary vasoconstriction, decreased stroke volume and cardiac output, bradycardia and increased systemic vascular resistance)
• accentuation of preexisting hypercapnia (increased CO2 associated with supplemental O2 in pts with chronic compensated resp acidosis
• airway injury (larger airway inflammation, erythema, and edema)
• parenchymal lung injury (destruction of alveolar tissue likely secondary to O2 free radicals causing inflammation and cellular death)

Question 18

Oxygen Toxicity

Prevention

Answer 18

• FIO2 less than 60% likely safe without toxicites

- aim for PaO2 60-70 mmHg or SpO2 90-93% with therapies

Question 19

Hypoxic drive pathophys

Answer 19

• chemoreceptors normally rely on CO2 levels to regulate ventilation
• if chronic elevated CO2 levels occur the body resets and becomes less sensitive to elevated CO2 and the drive to breathe shifts over to rely on lower levels of O2
• in these patients the addition of supplemental O2 can decrease the drive to breathe and maintain their minute ventilation leading to worsening respiratory failure.