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CBRC > Med Administration-Specialty Gases > Flashcards

Med Administration-Specialty Gases Flashcards

1
Q

—Nitric Oxide

A

—A diatomic molecule

—Colourlessgas at room temperature

—Non-flammable but supports combustion

—A free radical with a half-life of 3-50 s

—Highly diffusible and lipid soluble

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2
Q

Nitric Oxide in the Body

A
  • —Produced endogenously in vascular endothelial cells
  • —Is an important mediator of physiologic function including:
    • —Vasodilation
    • —Neurotransmission
    • —Long-term memory
    • Immunologic defense
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3
Q

NO and Smooth muscles

A

—Physiologically causes relaxation of smooth muscle

—Wheninhaledin small concentrations NO is potent pulmonary vasodilator

—Considered to be a ‘selective’ pulmonary vasodilator as it only affects ventilated alveoli

—Thus NO increases blood flow only to ventilated alveoli by relaxing the smooth muscles of the capillaries supplying these alveoli

—This vasodilation results in a decreased PVR-So we can get decreasing PVR without decreasing SVR!!

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4
Q

pulmonary vasodilation results in

A

—Decreased intrapulmonary shunting

—Improved oxygenation

—Decreased PVR

—Decreased pulmonary artery pressures

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5
Q

Inhaled NO effects are limited to

A

—The effects are limited to the pulmonary circulation because after diffusing into the capillaries NO immediately binds to hemoglobin

—This forms nitrosylhemoglobinwhich is rapidly oxidized to methemoglobin(metHb)

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6
Q

Nitric Oxide: The Indications

A

—ARDS

—PPHN

—Primary pulmonary hypertension

—Pulmonary hypertension post cardiac-Sx

—Heart transplantation

—Acute pulmonary embolism

—COPD

—Bronchodilation

—Congenital diaphragmatic hernia

—Congenital heart disease

—Testing pulmonary vascular responsiveness

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7
Q

NO and methacholine challanges

A

Studies show NO reverses the bronchoconstriction resulting from histamine and methacholinechallenges.

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8
Q

—Most C​ommon Uses-Pulmonary Vasodilation

A

NO is primarily used for its selective pulmonary vasodilator effects!

PPHN

—Congenital heart defects

—ARDS

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9
Q

NO use for ARDS

A

No improvement in mortality is seen with the use of NO on ARDS (adult) patients

FDA has not approved NO for widespread use in the Tx of ARDS.

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10
Q

—Most Common Uses-Bronchodilation

A

—Usually to reverse methacholineor Common bronchoconstriction

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11
Q

NO Dose

A

—Therapeutic dose range 2-80 ppm (Neo – 20 ppm)

—Beneficial effects appear to peak at about 10 ppm in adult ARDS patients

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12
Q

NO Choosing the Dose

A

Will depend on hospital P&P

Start at 10 ppm and do an ABG after 5 min

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13
Q

Changing NO based on ABG results

A

—If no response (PaO2increases <10 mmHg, SpO2increases <2% or MPAP does not decrease by at least 5 mmHg) then increase to 20 ppm

—If still no response:

—For ARDS—discontinue NO (treatment failure!)

For pulm. HTN—increase to 40 ppm and assess response

Patient’s should then be optimized to the lowest dose that shows a favorable response!

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14
Q

Weaning NO

A

Wean NO by 2-4 pm Q5 min while monitoring SpO2 and mean PAP.

If SpO2 falls by > 2% or mean PAP increases by > 5 mmHG return to last effective dose.

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15
Q

NO Toxcity

A
  • —In high concentration (5000-20,000 ppm) NO causes acute pulmonary edema and can lead to death
  • —Lower concentrations are associated with direct cellular damage and impaired surfactant production
  • —Most toxic effects are due to its by-products:
    • —NO2
    • —Nitric Acid
    • —Methemoglobin
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16
Q

NO2

A

—Nitrogen dioxide is produced when NO reacts with oxygen

—Is a reddish-brown gas

—More toxic than NO

The higher the FiO2 the more NO2 formed!

Clinically the goal is to keep NO2< 2 ppm!

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17
Q

Nitric Acid

A

—Forms when NO reacts with H2O

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18
Q

—NO2 and Nitric Acid Will Cause

A

In order of increasing dose

—Cell damage

—Chemical pneumonitis

—Hemorrhage

—Pulmonary edema

—Death

19
Q

—Methemoglobin Creation

A

Any NO diffusing into the capillaries immediately binds to Hb resulting in metHb

20
Q

High Levels of —Methemoglobin

A

—High levels of metHb will reduce the oxygen-carrying capacity of the blood

21
Q

Normal —Methemoglobin

A

—Normal metHb is < 2%

22
Q

Methemoglobinemia

A

—Methemoglobinemia is defined as metHb> 2%

—Methemoglobinemiais not commonly seen at the therapeutic dose of NO

—Causes blood to appear rusty brown in colour

23
Q

—MetHg>30%

A

—MetHg>30% can be treated with methylene blue

24
Q

MetHb and Oximetry

A

—Oximetry readings may be erroneously high.

25
Q

NO Adverse Effects

A
  • —Poor or paradoxical response
    • —As many as 40% of ARDS patients show no improvement with administration of NO
    • —Some patients develop worse hypoxemia
  • —Platelet inhibition
  • —Increased left ventricular filling pressures
  • —Rebound Effect
    • —Seen during the withdrawal of NO therapy
    • —May result in worse hypoxemia and pulmonary HTN then before therapy
26
Q

NO Methods of Administration

The Ideal System

A

—Is dependable and safe

—Provides precise and stable NO delivery

—Limits NO2 production

—Provides accurate NO and NO2 monitoring

—Permits scavenging of NO

—Maintains proper ventilator function

27
Q

NO Methods of Administration

Scavenging

A

Scavenging may be done to prevent exposure to health care workers. There is a safety limit of 5 ppm.

Not often done clinically as we won’t approach these levels.

28
Q

NO and FiO2

A

Adding NO will reduce the FiO2, the FiO2 must be analyzed distal to where NO is added

29
Q

Nitric Oxide: Administration

—Spontaneous Breathing vs. Ventilated

A
  • —Typically NO is administered in a ventilated patient
    • —Must have an oxygen analyzer downstream from the T in point as NO will effect FiO2
    • —An NO/NO2analyzer must also be used
  • —Spontaneously breathing patients
    • —Not commonly done, but is done with the INOvent sys
    • —Simple circuit of corrugated tubing with NO, air and O2blended to get desired FiO2and ppm of NO
    • —Again, FiO2, NO and NO2are analyzed prior to the patient
30
Q

Nitric Oxide: Withdrawal of Therapy

A

Care has to be taken in order to prevent the rebound effect

Exception- If the patient was a non-responder

31
Q

Nitric Oxide: Withdrawal of Therapy

Steps

A

—NO reduced to lowest effective dose-Ideally <5 ppm

—Pt should be hemodynamically stable with adequate oxygenation on FiO2£0.40 and low level PEEP

—Pt should be hyperoxygenated (FiO20.60-0.70) just prior to discontinuation

32
Q

FloLan

A
  • —Epoprostenolsodium
  • —Naturally occurring metabolite of arachidonicacid
  • —It is a prostaglandin with several profound effects
    • —Inhibits natural platelet aggregation
    • —Reduces pulmonary hypertension (some systemic action as well)
  • —Low dose may cause some vagally mediated bradycardia but at higher doses may cause a rebound tachycardia
  • May be referred to as a prostacyclin in some literature
33
Q

Heliox Density

A

Heliox is a low densitygas used to decrease the WOB!

Helium is light with a density of 0.1785 g/L is lighter than air, and hydrogen is the only gas that is lighter

Viscosity is higher than air

34
Q

Helium Properties

A

Odorless

Tasteless

Non-flammable

35
Q

Heliox Mixtures

A

Must be combined with oxygen

—Common mixtures

—20% O2, 80% helium

—30% O2, 70% helium

36
Q

Heliox and Upper Airway

A

—Turbulent flow in large airways is affected more by gas density than viscosity

—Breathing a low density gas improves flow through these airways

37
Q

Heliox and Lower Airway

A

—Have laminar flow, flow affected more by viscosity than density

38
Q

Heliox Upper airway Indications

A

—Airway Tumor

—Post extubation stridor

—Pediatric airway obstructions

39
Q

Heliox Lower airway Indications

A

—Severe COPD/Asthma

—Combined with NIPPV and/or mechvent

—Evidence is not clear, but promising.

—

40
Q

Heliox Delivery Mechanisms

—If using Heliox mixture (20% O2/80% Helium)

A

—Use tight fitting NRM

41
Q

Heliox Delivery Mechanisms

—If using separate oxygen/helium tanks

A

—Must monitor FIO2

—Ensure adequate FiO2 delivered to patient

42
Q

Heliox Delivery Mechanisms

—For aerosol delivery

A

—Increase flow to ensure nebulizer power is adequate

—May improve aerosol penetration

43
Q

Heliox Delivery Mechanisms

Mechanical Ventilation

A

—May alter Vt measurement

—Some vents now have Helioxoption

CBRC (20 decks)

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