Technology as one of the

success factors

Technology plays an important part when it comes to successful NIV. Ventilator-patient synchrony is an important goal. Studies underline that dedicated NIV devices perform much better in this category.

 

One factor of successful NIV is the available equipment and technology used. Failure of NIV may at times be related to ventilator-patient asynchrony and resulting discomfort. Generally, high patient comfort during NIV is associated with better synchrony.¹

 

Patient ventilator synchrony refers to the ability of a ventilator to detect patient triggering signals to deliver a breath, and cycling signals to stop the breath. The rapidity with which the device reacts to the information gathered will also impact performance. The ability of the ventilator to provide sufficient flow to match the patient demand will be an additional factor contributing to good patient ventilator synchrony. Both these aspects of synchrony are more difficult to achieve in leak prone environments. It is important to consider that leaks are a fact of life in NIV. If the clinician strives to remove leaks, the mask will inevitably be too tight and will cause discomfort. Eventually, over-tightening may cause pressure sores. It is best to use the most adapted equipment for the job, that is devices shown to adapt quickly and automatically to changing leaks. Remember leaks change from breath to breath!

 

A study published in Chest 2012 compared 19 ventilators in bench testing simulating spontaneous breathing efforts to assess the respective impact of inspiratory and expiratory leaks on cycling and triggering functions. Additionally, a second clinical study evaluated the incidence of patient-ventilator asynchronies in 15 patients during 3 randomized consecutive 20 minute periods of NIV using an ICU ventilator with and without its NIV algorithm engaged and a dedicated NIV ventilator. The conclusion showed that dedicated NIV ventilators allow better patient-ventilator synchrony in the presence of leaks than ICU and transport ventilators, even if their NIV algorithm is engaged, especially for what concerns auto-triggering.²

 

Learn more about dedicated NIV ventilators here.

 

In their 2008 article, Ambrosino and Vagheggini state the use of “conventional ventilators designed for invasive ventilation should be strongly discouraged, since failure rates are inappropriately high. […] ventilators with availability of monitoring of functions, such as airways pressures, tidal volume and airflow, are preferable.”³

 

 

Ventilators designed for use with an endotracheal tube are not leak tolerant, which creates issues of patient-ventilator asynchrony

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Side note

Ventilation modes

 

AVAPS, a new hybrid approach to NPPV, combines the advantages of pressure and volume modes by allowing the delivered pressure to vary in response to changes in tidal volume to guarantee an average preset value.


AVAPS

 

AVAPS stands for Average Volume-Assured Pressure support. The ventilator automatically modifies pressure to maintain an average target user-defined VT:

 

1 cmH2O to possibly 2.5 cmH20 per minute change in pressure

 

During AVAPS setup, there may be a period of time before the target tidal volume is achieved.

 

AVAPS should not be used when rapid IPAP adjustments are needed to achieve the desired VT.

 

AVAPS automatically adapts pressure support (< 2.5 cmH2O) per minute to guarantee an average tidal volume.

technology-image

AVAPS is an ideal mode for neuromuscular disorder patients. With standard bi-level therapy, a patient’s tidal volume declines as the disease process worsens. AVAPS would compensate for loss of effort on behalf of the patient to guarantee the tidal volume.

 

In patients with restrictive thoracic, it can be a slow progress disease process. AVAPS can help assure that tidal volume deliver.

 

In patients with Obesity Hypo-Ventilation Syndrome, any change in body position can decrease compliance which can decrease tidal volume. Without an increase in pressure support, the tidal volume will be lost. AVAPS helps assure that the patient will obtain the tidal volumes in the presence of body position changes.

In short, any chronic disease process that is past the acute phase can benefit from AVAPS.

 

PCV:

  • In pressure controlled ventilation, a set IPAP pressure and user set I-time is delivered to the patient

                    1.Every breath is delivered at a set I-Time

                    2.The patient does not control the inspiratory time

 

  • PCV may have an application in certain noninvasively ventilated patients

In PCV all breaths look the same, as machine determines I-time

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PCV on the V60 versus an ICU ventilator:

  • PCV on an ICU ventilator is PEEP compensated

If PEEP is 5 cmH2O and set pressure is 15 cmH2O

  • PIP is 20 cmH2O
  • On the V60 as well as other NIV ventilators, PEEP is not compensated

If EPAP is 5 cmH20 and IPAP is 15 cmH20
PIP is 15 cmH2O

  • Changes in EPAP without an equal change to IPAP

Results in a change in pressure support (delta pressure)

 

PCV mode can be beneficial for patients &nbsp;who may not be able to sustain a breath, e.g. in neuromuscular disorders (Muscular dystrophy, ALS) or chronic disease processes (restrictive diseases) as well as patients who are not tachypneic and are experiencing muscle fatigue, may VT by time at IPAP pressure.

 

PCV shouldn’t be used for patients with fast respiratory rates because PCV breaths are time-cycled and longer I-times may lead to patient-to-ventilator asynchrony.

 

Furthermore, it also shouldn’t be used in patients with respiratory distress as the Auto-Trak algorithm may not function as it was designed due to the timed mechanical breaths. Fatigue may occur as WOB may increase and Auto PEEP may be exacerbated.

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Despite its proven benefits to improve patient comfort and reduce mortality and also costs, noninvasive ventilation (NIV) is still underutilized at many hospitals. This website is designed to promote the usage of NIV by sharing the many situations in which NIV improves patients’ outcomes as well as to inform about the factors which are important in order to perform successful NIV.

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