Critical Care Exam I

How does noninvasive ventilation support ventilation?

without an artificial airway

What provides the earliest example of NIV?

bag-mask device

NIV includes what devices?

Noninvasive positive pressure ventilation (NPPV) and Noninvasive application of continuous positive airway pressure (CPAP)

Early devices of NIV relied on what 2 things?

intermittent application of abdominal pressure and the force of gravity 

Older NIV devices where most effective for what kind of disease?

neuromuscular or neurologic disease in the absence of primary pulmonary disease 

Older versions of NIV where capable of generating what range of tidal volume?

Tidal volumes (V_T) in the range of 4-6 ml/kg predicated body weight (PBW) in appropriately selected patients

What is IPAP setting used for?

help blow off CO²

What is the setting EPAP used for?

regulate FIO2

What is a pneumobelt NIV?

A rubber bladder strapped to the abdomen

What does a pneumobelt NIV do?

Bladder filling compresses abdominal contents pushing up diaphragm causing exhalation, when the bladder deflates it causes the diaphragm to fall and inhalation occurs. Patients prefer this while in a wheelchair.

What does the rocking bed NIV device do?

Periodically rocks from Trendelenburg position to reverse Trendelenburg position 

How does the rocking bed NIV work?

uses gravity to produce exhalation and inhalation

What is a negative pressure ventilator (NPV) do?

negative pressure around thorax causes pressure gradient across chest wall- inspiration occurs

What are the 2 types of negative pressure ventilators (NPV)?

Iron lung and chest cuirass

The iron lung was used widely for what epidemic?

Polio 1920s-1960s

What does the iron lung do?

surrounds the entire body and provides negative pressure ventilation a porta lung is a simpler cheap version of the iron lung

What are the goals and benefits of using NIV in an acute care setting?

reduces need for sedation

improve gas exchange

avoid intubation

decrease mortality

decrease length of time on the ventilator and length of hospitalization

decrease incidence of ventilator associated pneumonia

relieve symptoms of respiratory distress improve patient ventilator synchrony

maximize patient comfort

preserves physiological airway defense 

What is the primary goal of NIV?

avoid intubation

What are the goals and benefits of using NIV in a long term care setting?

relieve or improve symptoms of chronic hypoventilation 

enhance quality of life 

avoid hospitalization 

increase survival 

improve mobility and functional capacity

improves duration and quality of sleep  

What are indications of NIV in an acute care setting?

COPD particularly hypercapnic respiratory failure due to COPD is primary indication for NIV

When using NIV in the acute care setting for COPD exacerbation there is strong evidence in the efficiency in reducing what?

the need for intubation, hospital mortality, length of stay, and complications

What is the standard of care and first line therapy for managing an acute COPD exacerbation?

NIV

When using NIV in an acute care setting to treat asthma what are the indications?

the evidence is inconclusive and the use remains controversial

When using NIV to facilitate weaning what are the indications and benefits?

COPD patients who failed SBT, lower mortality after 60 days, and patients selected should have used NIV previously and should meet none of the NIV exclusion criteria

What patients benefit from BIPAP?

COPD, CHF, and ARF

What are the indications for the use of NIV in the acute care setting for the use of treating hypoxemic respiratory failure?

clinical trials of NIV to manage acute hypoxemic respiratory failure have yielded conflicting results

What are the indications for the use of NIV in the acute care setting for the use of treating acute cardiogenic pulmonary edema?

Mask CPAP of 8-12 cmH2O and 100% O2 is first line therapy to treat hypoxemia associated with severe cardiogenic pulmonary edema and NPPV is reserved for those with ventilatory failure

When treating acute cardiogenic pulmonary edema with NIV and the patient remains hypercapnic and dyspneic on CPAP what should be done?

a trial of NIV is indicated

What are the indications for the use of NIV in the acute care setting for the use of treating pneumonia?

improves outcome ONLY for COPD patients who develop pneumonia

What are the indications for the use of NIV in the acute care setting for the use of treating acute lung injury and ARDS?

*patients with risk factors such as hemodynamic instability, metabolic acidosis, or profound hypoxemia are more likely to fail 

*The evidence to date does not support routine NIV use in patients with ALI/ARDS 

Failure was predicted if PaO₂/ FiO₂ ratio was less than 175 after the first hour of NIV

What are the indications for the use of NIV in the acute care setting for the use of treating immunosuppressed patients?

RCTs involving immunosuppressed patients and patients awaiting solid organ transplantation who developed hypoxemic respiratory failure found decreased intubation rates and mortality with NIV compared with standard therapy

What are the indications for the use of NIV in the acute care setting for the use of treating DNI and comfort measures only?

use only if it makes patients more comfortable or to manage a reversible disorder

What are the indications for the use of NIV in the acute care setting for the use of treating post operative patients?

insufficient evidence to support NIV

What are the indications for the use of NIV in the acute care setting for the use of treating post operative respiratory failure?

requires a caution approach

if hypoxemia does not significantly improve with NIV, these patients should be reintubated without delay

What are the indications for the use of NIV in the acute care setting for the use of treating prevention of reintubation in high-risk patients?

studies have shown lower reintubation rates with NIV

Patients with hypercapnia gained the most benefit from NIV

What are the indications for the use of NIV in the long term care setting for the use of treating Nocturnal hypoventilation?

*common in patients with neuromuscular diseases, severe kyphoscoliosis, COPD, obesity, and central and obstructive sleep apnea

Use NIV to prevent chronic hypercapnia and associated hypoxemia

Helps by resting muscles, lowering CO₂, and improve compliance, FRC, and dead space

Patients with obstructive sleep apnea are treated with CPAP but if the patient continues to have hypoventilation/nocturnal desaturation what is indicated? 

Noninvasive ventilation (BIPAP)

What are the initial settings for IPAP and EPAP levels?

IPAP 8-12

EPAP 4-5

What are the indications for the use of NIV in the long term care setting for the use of treating restrictive thoracic diseases?

current recommendation is to initiate NIV when patients develop symptoms of nocturnal hypoventilation

Little evidence to support prophylactic NIV

What are the indications for the use of NIV in the long term care setting for the use of treating amyotrophic lateral sclerosis?

NIV is probably effective in prolonging the lives of patients with ALS

Evidence suggests that using NIV slows the rate of lung function decline as indicated by FVC measurement

What are the indications for the use of NIV in the long term care setting for the use of treating stable COPD?

positive inspiratory pressure improves gas exchange and may unload the respiratory muscles, allowing them to recover, gain strength, and reduce fatigue resulting in improved quality of life

should decrease the symptoms of nocturnal hypoventilation and sleep disordered breathing

at the present time, there is not enough evidence to support routine treatment with NIV in patients with stable COPD

What are the indications for the use of NIV in the long term care setting for the use of treating obesity hypoventilation syndrome (OHS)?

Defined as chronic daytime hypoventilation (PaCO2 greater than 45 mmhg) associated with obesity (body mass index greater than 30 kg/m2) when no other known cause for hypoventilation is present

A RCT of CPAP versus NPPV in patients with OHS without severe nocturnal desaturations found that both modes were equally effective in decreasing daytime PaCO2

At the present time nocturnal NPPV is recommended for OHS when nasal CPAP and other first-line therapies fail to alleviate the hypoventilation

When selecting NIV for acute respiratory failure patients two or more of what should be present?

use of accessory muscles

paradoxical breathing

respiratory rate greater than or equal to 25 breaths/min

moderate to severe dyspnea (increased dyspnea in COPD patients)

PaCO2 greater than 45mmhg with pH less than 7.35

PaCO2/FiO2 ratio less than 200

What is the exclusion criteria for using NIV on patients with acute respiratory failure?

apnea

inability to protect airway/high aspiration risk

hemodynamic or cardiac instability

lack of patient cooperation

inability to use a noninvasive interface because of facial burns, trauma, or abnormal anatomy

excessive amount of secretions

When selecting appropriate patients for NIV what are the predictors for success in the acute care setting?

minimal air leak

low severity of illness

respiratory acidosis (PaCO2 greater than 45 mmhg but less than 92 mmhg)

pH less than 7.35 but greater than 7.22

improvement in gas exchange within 1 to 2 hours of initiation

improvement in respiratory rate and heart rate

When selecting appropriate patients for the use of NIV in the long term care setting to treat restrictive thoracic diseases what should occur?

patients should have symptoms of chronic hypoventilation and lack of sleep quality 

*Patients should meet one of the following measurable parameters: 

PaCO2 45 mmhg or greater, nocturnal O2 saturation les than 88% for 5 minutes, maximal inspiratory pressure less than 60 cmH2O, or FVC less than 50% of predicted 

When trying to find if a patient has a V/Q mismatch or alveolar hypoxemia what should you do?

Add CO2 and PO2

When trying to find if a patient has a V/Q mismatch or alveolar hypoxemia what are the indicated values?

less than 110 indicates V/Q mismatch indicating the patient wont respond to O2

110-130 indicates alveolar hypoxemia indicating the patient will respond to O2

When a COPD patient is placed on BIPAP what are the target values?

10/5 with 50%

When selecting appropriate patients for the use of NIV in the long term care setting to treat nocturnal hypoventilation caused by disorders other than restrictive lung disease what should occur?

first line therapy includes weight loss, O2 therapy, respiratory stimulants, and CPAP

NIV is recommended as the initial therapy for moderate to severe cases

What is the exclusion criteria for NIV in long-term care?

relative contraindications for the use of NIV for restrictive thoracic disease

nocturnal hypoventilation

chronic COPD

an unsupportive family

copious amount of secretions

uncooperative behavior on the part of the patient

high risk for aspiration

anatomic abnormality that interferes with gas delivery

What are the most common types of NIV patient interfaces?

nasal mask 

full face mask (oral mask)

mouthpiece 

What are the less common types of NIV patient interfaces?

hybrid mask

total face mask (covers whole face)

nasal pillows

helmet

What does a NIV nasal masks entail?

triangular in shape only covers the nose

made of hard, clear plastic with a cushion below for contact with the face 

A strap assembly holds mask on face 

When using a nasal masks for NIV what should you avoid?

do not overtighten because it may cause tissue necrosis

Proper sizing of a nasal mask for NIV helps ensure?

reduces incidence of pressure sores and tissue necrosis

reduces leaks

increases patient comfort

improves likelihood of long term patient tolerance

A full face mask used for NIV is the primary choice for what patient?

Patients with acute respiratory failure

more than 90% of this group should start with full face mask

A full face mask for NIV is designed for either?

noninvasive ventilators: entrainment valve that prevents asphyxia if ventilator fails

ICU ventilators: entrainment valve absent

In all modes of bilevel positive pressure ventilation the patients delivered tidal volumes depends on the gradient between? 

The IPAP and EPAP, inspiratory time, and the patients inspiratory effort and lung characteristics 

To prevent CO2 rebreathing EPAP levels should be set at?

4 cmH2O or higher so adequate gas flows can flush CO2 from the breathing circuit

NIV should be considered for patients with severe stable COPD who are?

symptomatic despite optimal treatment

NIV should be considered for COPD patients who demonstrate evidence of?

OSA and are unresponsive to CPAP therapy

Improvement in patient comfort is indicated by?

decreased RR, decreased muscle activity, and synchronized with the vent

What are the disadvantages of a full face mask compared to a nasal mask?

Increased dead space, claustrophobia, risk of aspiration

harder to talk and expectorate

What are the qualifications for CPAP after a sleep study?

apnea for greater than or equal to 25 seconds 

episodes of apnea 5 within 1 hour 

What are the 3 types of ventilators used for NIV?

noninvasive ventilators

critical care ventilators

portable home care ventilators

Most NIV are?

electrically powered, blower driven, microprocessor controlled

Noninvasive ventilators are designed to work with?

a small leak and compensate for that leak

Most NIV are desired to have?

internal oxygen blender but difficult to obtain greater than 0.5 FiO2

What are the modes availiable on NIV?

CPAP, spontaneous (pressure support), and timed (pressure assist/ control)

When using critical care ventilators what is common?

Triggering and cycling issues, lots of nuisance alarms, and use a full face mask to minimize leaks

When using a critical care ventilator it often results in triggering and cycling issues affecting what?

PSV breaths end at set percent peak flow; if flow does not fall to set percent, may lock in inspiration

modern vents can adjust cycle off percent

time cycling solves problems and improves patient comfort

Critical care ventilation is indicated when?

CPAP, PSV, and P-A/C have all been used

VC modes used but not recommended as it leaks and can lead to hypoventilation

There are various NIV packages are now on ICU ventilators and some will?

compensate for leaks

allow audio alarm deactivation

set maximum inspiratory time*

What are the advantages of portable home care or transport ventilators?

electrically powered and microprocessor controlled

can operate from alternating current (AC) or if equipped with internal or external batteries, direct current (DC) power sources

the batteries usually can provide power for several hours

updated technology has improved for performance characteristics of these ventilators to a level comparable to critical care ventilators with the added advantages of small size, light weight, and battery power that allow portability

Portable home care ventilators are currently recommended for?

patients who need continuous ventilatory support or high ventilating pressures

for acute care these ventilators could easily be used to initiate NIV in nontraditional locations and allow transport to an emergency department or ICU without the need to interrupt ventilation

For S/T mode (or A/C mode) clinician sets?

IPAP and EPAP, RR, and inspiratory time (IPAP%).

Patient may initate breaths that are supported to the IPAP level but if the patient fails to make an inspiratory effort within a set interval, the machine triggers inspiratory to the set IPAP level. IPAP then cycles to EPAP based on the IPAP% (inspiratory time)

Adjust NIV by patient presentation and ABGS what should you initiate when the PaCO2 is high or low?

If the PaCO2 is high increase pressure (VT) or rate

If the PaCO2 is low decrease pressure (VT) or rate - often rate is for backup only; if set in A/C may have above effects, but patient inspiratory efforts override ventilator setting

Adjust NIV by patient presentation and ABGS what should you initiate when the PaO2 is high or low?

if the PaO2 is high decrease oxygen or PEEP

if the PaO2 is low increase oxygen or PEEP - when PEEP is adjusted it may alter pressure gradient and thus VT

What are the causes of NIV failure?

mask related problems 

flow related problems 

larger air leaks 

patient ventilator asynchrony 

lack of improvement in gas exchange 

What are major complications of NIV?

aspiration, hypotension, and pneumothorax

What are the contraindications for CPAP?

aspiration

vomiting

spontaneous breathing

increased apnea

pneumothorax

hypoventilation

increased WOB and accessory muscle use→ fatigue

facial trauma with instability to withstand CPAP

claustrophobia

When a patient becomes fatigued on CPAP what are the symptoms?

increased WOB

altered LOC/mental status 

dyspnea 

tachycardia 

increased PaCO2 

increased RR 

increased tidal volume (VT) 

decreased NIF 

decreased vital capacity