medical gas delivery

inspiratory demand

vt=vxti

What is retinopathy of prematurity and what can it cause

- Also called retrolental fibroplasias: Abnormal eye condition in some premature or low birth weight infants caused by supplemental oxygen - Excessive blood oxygen levels cause retinal vasoconstriction: causes necrosis of the blood vessels - Hemorrhage of the delicate vessels causes scarring behind the retina which can lead to retinal detachment and blindness - can affect neonates up to 1 month of age - hypercapnia, infection, anemia, hypothermia is also associated with ROP PaO2 greater than 80 with oxygen therapy in infants and neonates can cause retinopathy of prematurity

O2 induced hypoventilation

- COPD and chronic hypoxemia and hypercarbia - COPD rely on low levels of o2 to initiate breathing to much o2 will stop breathing -use venturi mask if tolerated

Indications of O2 therapy

- Documented hypoxemia: 1. PaO2 less than 60 mmHg 2. SaO2 less than 90% on room air 3. Severe trauma 4. Acute Myocardial Infarction (or suspected) 5. Short term therapy (post-anesthesia)

high flow oxygen

- Supply a given oxygen concentration at a flow equal to patients inspiratory demand - An air entrainment or lending system is used (except in case of NRB) - RULE OF THUMB: to qualify as a high flow device must provide at least 60LPM total flow

low flow oxygen

- typically provides supplemental O2 to the patients directly to the airway at a flow of 8 LPM or less - provides only part of the patient's inspired volume - low flow oxygen devices include: nasal cannula, nasal catheter, and the transtracheal catheter

Low-Flow Oxygen Delivery Systems

-Nasal cannula -Simple face mask -Partial rebreather mask -Nonrebreather mask

The objectives of Oxygen Therapy are:

1. Correct hypoxemia 2. Decrease symptoms associated with hypoxemia (WOB) 3. Decrease workload hypoxemia puts on cardiovascular system (WOH) Correcting Hypoxemia

When using Heliox, how would you calculate the actual Heliox flow from the observed O2 flow on the flowmeter (10 L/min)?

80% He / 20% O2 = Heliox factor: 1.870% He / 30% O2 = Heliox factor: 1.660% He / 40% O2 = Heliox factor: 1.4Observed flow on flow meter (10 L/min) X factor (1.8) = 18L/min of actual Heliox flow

When to add humidity to nasal cannula, what to do if humidifier pop off alarm is sounding and what is possible cause for alarm?

4lpm

Complications associated with hyperbaric O2 therapy

Barotrauma ØEar or sinus trauma ØTympanic membrane rupture ØAlveolar overdistention and pneumothorax ØGas embolism Oxygen toxicity ØCNS toxic reaction ØPulmonary toxic reaction Other ØFire ØSudden decompression ØReversible visual changes ØClaustrophobia ØDecreased cardiac output

Indications for hyperbaric o2 therapy

Acute conditions ØDecompression sickness ØAir or gas embolism ØCarbon monoxide and cyanide poisoning ØAcute traumatic ischemia (compartment syndrome, crush injury) ØAcute peripheral arterial insufficiency ØIntracranial abscesses ØCrush injuries and suturing of severed limbs ØClostridial gangrene ØNecrotizing soft tissue infection ØIschemic skin graft or flap Chronic conditions ØDiabetic wounds of the lower extremities and other nonhealing wounds ØRefractory osteomyelitis ØActinomycosis (chronic systemic abscesses) ØRadiation necrosis (HBO as an adjunct to conventional treatment)

Fio2 changes with downstream resistance for Air Entrainment nebulizer

Any increase in flow resistance downstream from (distal to) the point of air entrainment alters the performance of all air-entrainment systems ØIncreased downstream flow resistance causes back pressure ØBack pressure decreases both the volume of entrained air and the total flow output of these devices With less air entrained, the delivered O2 concentration increases ØBecause total flow output also decreases, the effect on FiO2 varies

Complications and Hazards of HBO

Barotrauma ØEar or sinus trauma ØTympanic membrane rupture ØAlveolar overdistention and pneumothorax ØGas embolism Oxygen toxicity ØCNS toxic reaction ØPulmonary toxic reaction Other ØFire ØSudden decompression ØReversible visual changes ØClaustrophobia ØDecreased cardiac output

Therapeutic use for heliox therapy

Can decrease work of breathing for patients with airways obstruction

Trouble shooting a NRB bag collapse, no collapse, slight collapse

Common problems with reservoir masks include: ØDevice displacement ØSystem leaks and obstructions ØImproper flow adjustment ØSkin irritation

What occurs to FiO2 when air entrainment ports are blocked

Delivered O2 concentration increases, but total output flow decreases

Interfaces for air entrainment nebulizers

Direct a high-pressure O2 source through a small nozzle or jet surrounded by air-entrainment ports The amount of air entrained at ports varies directly with the size of the port and the velocity of O2 at the jet FiO2 provided by air-entrainment devices depends on two key variables: ØThe air-to-O2 ratio ØThe amount of flow resistance downstream from the mixing site

Minimum LPM for simple mask and why?

Flows less than 5 LPM will allow the mask to act as deadspace and causes CO2 rebreathing

criteria for HBO in CO poisoning

History of unconsciousness Presence of neuropsychiatric abnormality Presence of cardiac instability or cardiac ischemia Carboxyhemoglobin level 25% (lower levels for children and pregnant women)

When should nonrebreathers be used

Most often used in patients who need high‐concentration oxygendelivery (10 to 15 L/min)• Should not be used in patients with apnea or poorrespiratory effort

What is the problem with input flows greater than 10 to 15 L/min in an infant Oxy-Hood?

Production of harmful noise levels

Device of choice for severe chest pain with central cyanosis

Simple Mask O2 Mask @ 8 L/min

FiO2 (fraction of inspired oxygen)

The concentration of oxygen in the air we breathe

flow output from flowmeter for heliox 80/20 and 70/30 mixtures?

The heliox factor for a 70% He/30% O2 mixture is 1.6 and the heliox factor for an 80% He/20% O2 mixture is 1.8.

how to calculate total flow

Total flow = Flowmeter setting X factor (use magic box) i.e 5 L X 11 = 55 L/ min If you are given total flow and have to calculate flowmeter setting. Find the factor then divide that into the total flow Take the factor and multiply by each answer to see which one matches the total flow

High flow oxygen delivery systems

Venturi mask Face tent Aerosol mask Tracheostomy collar T-piece

What device is the BEST for patients with COPD?

cpap

how to calculate fio2

equals liters per minute flow * 4 + 20

0.6: 1 is the Air/O2 ratio If the flowmeter is set on 15 LPM Total Flow = 1.6 X 15 LPM = 24 LPM Another Example: 50% FiO2 15 LPM

flowmeter on 15lpm

Total flow formula

flowmeter setting x factor

device used to deliver heliox

heliox should be delivered to patients via tight-fitting nonrebreathing mask with high flow

LPM, L/min

liters per minute (usually referring to oxygen delivery)

What is target oxygenation goal for patients with chronic hypercapnia?

paO2 greater than 60 can depress ventilatory drive in patients with hypercapnia - When breathing high oxygen concentrations, COPD patients with chronic hypercapnia tend to ventilated less

Appropriate initial O2 device for COPD patient

venturi mask

Minimum LPM for simple mask

ØAt a flow less than 5 L/min, the mask volume acts as dead space and causes carbon dioxide (CO2) rebreathing FiO2 range is 0.35 to 0.50 ØAir dilution easily occurs during inspiration through its ports and around its body, provides a variable FiO2 ØFiO2 varies depending on the O2 input flow, the mask volume, the extent of air leakage, and the patient's breathing pattern

oxyhood: what is it used for, what is the flow ranges to be set at, what temps should be set, what should be monitored, what happens when temps gets too low or flows get to high or low

ØOxygen hood (AKA: Oxyhood): Generally is best method for delivering controlled oxygen to infants ØIncubators (AKA Isolette): Can be used in conjunction with oxyhood

hyperbaric O2: treatment, computing barometric pressures for ATA, physiologic effects

ØThe therapeutic use of O2 at pressures greater than 1 atm Physiologic effects ØBubble reduction (Boyle's law) ØHyperoxygenation of blood and tissue (Henry's law) ØVasoconstriction ØEnhanced host immune function ØNeovascularization A multiplace chamber is a large tank capable of holding a dozen or more people ØHave air locks that allow entry and exit without altering the pressure. ØGenerally filled with air ØIf indicated, only the patient breathes supplemental O2 (through a mask or another device). Monoplace chamber can hold only one patient