Monitoring during noninvasive ventilation

Monitoring during Noninvasive
Ventilation
Mostafa Elshazly
Professor Of Pulmonary Medicine
Chairman Of PCCU
Kasr Alainy School Of Medicine
Cairo University
elshazly66@hotmail.com

Monitoring
• Monitoring of patients undergoing NIV has the aim to
determine whether NIV is being performed safely and
effectively.

Monitoring
• Monitoring of patients treated with NIV should be
adjusted to the patient’s general status and the severity
of respiratory insufficiency.

Monitoring
• In fact, the majority of failures occur within the first 2 h
treatment, although ∼20–25% of patients may fail later after
an initial response to NIV.
• Early identification of NIV failure is of pivotal importance as
unduly delaying IMV may be associated with increased
mortality.

Monitoring
• Comfort
• Tolerance to interface
• Respiratory rate
• Dyspnoea and use of accessory muscles
• Gastric distention
• Disease severity scores (APACHE II)
Clinical Parameters

Monitoring
• Cough efficiency may be measured by means of peak cough
expiratory ﬂow; values <270 L⋅min-1 are considered at risk of
retention of secretions and indicate the need for manual and/or
mechanical cough assistance
Clinical Parameters

Monitoring
• Diﬀerent alterations in neurological status may be found in acute
NIV patients.
• The Glasgow Coma Scale (GCS) is largely applied to assess
sensorium level in ARF
• The Kelly–Matthay score is the best tool for measuring
neurological alterations secondary to gas exchange abnormalities
Clinical Parameters

Monitoring
• The Kelly–Matthay score is the best tool for measuring
neurological alterations secondary to gas exchange abnormalities.
• a score of >3 may raise the alarm for depressed consciousness
and high risk of NIV failure
Clinical Parameters

Monitoring
• The Richmond sedation–agitation scale is the more suitable
instrument for evaluating and monitoring the degree of
psychomotor agitation and the eﬀects of sedation during NIV in
poorly tolerant patients .
Clinical Parameters

Monitoring
• The Richmond sedation–agitation scale is the more suitable instrument for
evaluating and monitoring the degree of psychomotor agitation and the
eﬀects of sedation during NIV in poorly tolerant patients .
• Explaining the technique, asking the patient’s preference for
interface and initiation at low pressures followed by stepwise
increases may be helpful to overcome agitation; however, mild
sedo-analgesia may be beneficial in some patients for symptom
relief, improved patient tolerance and compliance
Clinical Parameters

Monitoring
• Besides the change in the level of consciousness, delirium may be
a problem in some patients.
• Although delirium is relatively a common problem, particularly in
ICU patients, it is underdiagnosed in patients receiving NIV.
• Delirium is reported to be directly associated with NIV failure
and mortality.
Clinical Parameters

Monitoring
• Therefore, daily routine screening of delirium during
NIV, using diagnostic aids such as the confusion
assessment method or nursing delirium screening scale,
should be encouraged
Clinical Parameters

Monitoring
• Whenever NIV is applied for ARF, assessment of gas
exchange, both at baseline and after the first few hours of
treatment, is mandatory to understand whether NIV may
be successfully continued or if IMV is required.
Physiological parameters

Monitoring
• Oxygen saturation
• Arterial blood gas analysis (pH, PaCO2, PaO2)
• Transcutaneous CO2
• End-tidal CO2

Monitoring
• Noninvasive continuous monitoring of SpO2
should be used in all patients during NIV

Monitoring
• In cases of hypercapnic ARF treated with NIV,
SpO2 targets should be 88–92%.
• SpO2/FIO2 ratio has been shown to be a good
marker of oxygenation and a surrogate of the
PaO2/FIO2 ratio

Monitoring
• Arterial blood gas analysis
• baseline
• after 1 and 4 h of NIV
• then at regular intervals depending on the patient’s response
• with every change to the ventilator settings
• finally, on spontaneous breathing to choose the timing for weaning
from NIV

Monitoring

Monitoring
• The agreement between PtcCO2 and PaCO2 turns out to
be accurate, especially in subjects with haemodynamic
stability and a moderate degree of hypercapnia (i.e. <70
mmHg )

Monitoring
• Moreover, the opportunity to obtain the trend in PtcCO2
and pulse oximetry under NIV may be helpful for the
clinician in adjusting the ventilator settings according to
suspected patient–ventilator asynchronies and/or
excessive unintentional leaks and/or sleep respiratory
disorders.

Monitoring
• NIV in order to reinforce the ventilatory pump and improve gas exchange must be
aware of its effects on the functioning of the cardiovascular system.
• These effects must be assessed continuously or periodically, to reveal potential side-
effects and manage them adequately, as the improvement of respiratory function can
be associated with the impairment of cardiac function.
• Positive pressures are very effective in decreasing PaCO2, but simultaneously may
considerably decrease cardiac output and oxygen delivery to tissues [
Cardiac parameters

Monitoring
Blood pressure
ECG
Echocardiography
Cardiac parameters

Monitoring
ECG
Cardiac parameters
➢ 12-lead ECG should be performed in all patients with ARF,
irrespective of the history of cardiac disorders.
➢ BTS/ICS guidelines recommend monitoring ECGs in all patients
with tachycardia >120 beats·min-1, dysrhythmias or possible
cardiomyopathy

Monitoring
Blood pressure
Cardiac parameters
➢ Hypotension (systolic blood pressure <90 mmHg) is considered to be a
relative contraindication to NIV ,particularly as a result of arrhythmia
➢ The aim is to monitor effect of the application of NIV.
➢ Monitoring in the first hour of treatment is strongly advisable.
➢ Monitoring vital signs every 30 min within first 6–12 h of treatment.

Monitoring
Echocardiography
Cardiac parameters
➢Echocardiography is a useful, noninvasive and easy to perform
bedside diagnostic tool.
➢Optimally, performed at the beginning of ventilation, in patients
with known or suspected underlying heart disease.
➢Otherwise, when disturbances of cardiovascular system occur in
the course of treatment.

Monitoring
• A full panel of biochemical tests should be performed in all
patients during NIV as the development of extrapulmonary
complications aﬀects the outcome.
Laboratory parameters

Monitoring
• Hyperglycemia is an independent predictor of NIV failure in
COPD exacerbations.
• Fluid balance should be assessed daily in all patients as
complications due to renal failure and ﬂuid overload are likely to
be correlated with NIV failure.
Laboratory parameters

Monitoring
Ventilatory parameters

Monitoring
Respiratory frequency
VTE, V′E
Leaks
Waveforms (flow–time, pressure–time, capnography)
PEEPi
Patient–ventilator interaction

Monitoring
• It is important to choose a ventilator with reliable
monitoring equipment.
• Ventilator monitoring includes the assessment of
numerical data with or without a graphical curve display.

Monitoring
Respiratory frequency
VTE, V′E

Monitoring
• VTE is the main parameter to monitor as it reflects the patient’s
alveolar ventilation under NIV.
• It is either measured directly by a proximal flow sensor in a
double-limb circuit system or calculated from the integral of the
flow signal with adjustments for unintentional leaks in a single-
limb circuit system

Monitoring
• Before starting NIV, the desirable VTE should be determined
• Ranges from 6 mL·kg−1 for neuromuscular and restrictive chest
wall disorders to 8–10 mL·kg−1 in OLD and obesity .
• Rapid shallow breathing index (RSBI) (RR divided by VTE in
litres)

Monitoring
Leaks

Monitoring
Leaks
Air leakage is an inevitable consequence of NIV, and efficacy of the
noninvasive respiratory support largely depends on the minimization of the
leaks.
Devices used for NIV must inform continuously about the
level of leakage in order to optimize the mask adherence.

Monitoring
• PEEPI causes dynamic hyperinflation , decreased respiratory
system compliance and increased respiratory workload.
• As the inspiratory muscles start to contract, they must first
overcome the threshold which is PEEPI before inspiratory flow
can start.

Monitoring
Patient–ventilator interaction during NIV
➢ Patient–ventilator synchronization is an important issue which can
influence the efficacy and success of NIV
➢ The most common phenomenon is ineffective triggering ( 2nd to high
PEEPi or inappropriate inspiratory trigger sensitivity), followed by auto-
triggering and double-triggering .

Monitoring
Patient–ventilator interaction during noninvasive ventilation

Patient–ventilator Interaction During NIV
Practical Assessment
• NIV is a “semi-open” system and therefore air leaks around the
mask are very likely to occur, in particular in the first few hours
of ventilation, when the patient needs to adapt, and later on
when prolonged mechanical ventilation is required.

• Patient–ventilator synchrony may be deeply affected by the:
• Air leaks
• Settings of the ventilator
• Interfaces used
• Emotional status of the patient.

• Forms of asynchrony, mismatching and detection
• triggering of the ventilator
• phase of inspiration after triggering
• passage from inspiration to expiration
• end of expiration

Monitoring
➢ Patient–ventilator asynchrony is a frequent phenomenon during NIV
➢ Substantial levels of asynchrony, defined as >10% of all patient’s
respiratory efforts, occur >40% of patients
➢ The number of asynchronies is correlated with the magnitude of leak
and higher pressure support.

Monitoring
➢ The most practical method should be analysis of the pressure and flow
waveforms

Monitoring
Waveforms (flow–time, pressure–time, )
➢ Observation of P/T & F/T waveforms during NIV can be useful not
only for detection of patient–ventilator asynchrony, but also other
additional information about the quality of the ventilation.
➢ Titration of ventilator settings on the basis of analysis of respiratory
waveforms in real time resulted in more rapid improvement in pH and
PaCO2 and better tolerance of ventilation by patients.

Monitoring
Other diagnostic and monitoring tests for the respiratory system
Radiologic evaluation
Lung ultrasonography

Monitoring
Lung ultrasound yields diagnoses for diaphragmatic dysfunction,
parenchymal lung diseases and pleural space pathologies, which
may give important clues for the management of patients requiring
mechanical ventilation

Monitoring

Monitoring
Thickening fraction (TFdi)) has been used to assess WOB and
respiratory effort.
TFdi predict extubation failure or success during a SBT in IMV patients

Monitoring
Monitoring side-effects
Side-effects related to NIV are usually mild, but they may
have a negative influence on NIV success.
Minor complications (interface or ventilatory circuit )
managed easily with appropriate interventions.
Serious side-effects are relatively rare, but if they occur,
discontinuation of NIV support should be considered.

Monitoring
Gastric distention
Decompression of gastric air using a nasogastric
tube should be considered as a preventive measure
in severe cases who have increasing abdominal
distention, persistent nausea and vomiting.
If vomiting occurs, the mask should be removed
immediately and cough should be encouraged for
airway clearance.

Monitoring
Secretion clearance
The presence of copious
secretions increases the
risk of NIV failure.
Physiotherapy techniques
and tracheal aspirations
may be helpful in some
patients.
Mechanical insufflation–
exsufflation should be used in
patients who have ineffective
cough and sputum retention
due to neuromuscular disease

Monitoring
Serious side-effects
Pneumonia Pneumothorax
➢ Semirecumbent position during NIV.
➢ ∼3–10% in patients receiving NIV
➢ basic infection control measures
relatively low (<5%) with NIV application
Patients who describe acute chest pain
and unexplained dyspnoea should be
screened using CXR or U/S.

Monitoring
• ETI must be rapidly assured, when indicated.
• Criteria used to perform ETI in ARF patients undergoing
NIV are as follows

Monitoring
(1) patient intolerance;
(2) inability to improve gas exchange;
(3) inability to improve dyspnea or respiratory muscle fatigue;
(4) Appearance of severe hemodynamic or electrocardiographic
instability;
(5) Severe neurological deterioration

Monitoring
• The benefits of NIV depend directly on choosing the right
patient and the correct application of the technique.
• Clinical parameters should be monitored every 30 min for the
first 6–12 h and then hourly after the initiation of support.
Clinical parameters to monitor during NIV

Conclusion
• NIV is a lifesaving therapeutic option, which should be proposed
to the vast majority of patients with ARF.
• Benefits of NIV can be obtained only if adequate monitoring of
patients is undertaken.
• The basis of monitoring patients treated with NIV is a regular
assessment of patient’s clinical status and continuous
monitoring of SaO2 and periodic ABG analysis.

Conclusion
• The important step in the course of treatment is the analysis in
real time of the ventilatory parameters of the patient (VTE, leak
and I:E ratio) provided by the ventilator as respiratory
waveforms and numerical data.

Monitoring during noninvasive ventilation

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