Oxygen Therapy - HealthManagement.org
←
→
Page content transcription
If your browser does not render page correctly, please read the page content below
ICU
MANAGEMENT & PRACTICE
INTENSIVE CARE - EMERGENCY MEDICINE - ANAESTHESIOLOGY VOLUME 21 - ISSUE 3 - 2021
Oxygen
Therapy
Oxygen Therapy in Intensive Care Medicine, Practical Strategies in Mechanical Ventilation
J. Grensemann, S. Sakka for Patients With Acute Respiratory Failure Due
Oxygen: Too Much is Bad, B. Pastene, M. Leone to COVID-19, O. Pérez-Nieto, E. Zamarron-Lopez,
J. Meade-Aguilar et al.
Oxygen Therapy in COVID-19 Patients: The Role of
HFNC and CPAP, S. Ferrari, A. Isirdi, E. Taddei et al. Airway Management in Critically Ill Patients –
Striving to Improve Outcomes, K. Karamchandani,
Apnoeic Oxygenation for Intubation - Where is the A. Khanna, S. Myatra
Evidence? A. De Jong, C. Monet, S. Jaber
Hyperoxia – A Journey to the Centre of the Cell,
Major Adverse Peri-intubation Events in Critically J. Poole
Ill Patients – Update on the INTUBE Study,
V. Russotto, S. Myatra, J. Laffey et al. Diaphragm Ultrasonography in ICU: Why, How,
and When to Use It? Y. Aarab, A. De Jong, S. Jaber
New Applications of Pulse Oximetry, F. Michard
icu-management.org @ICU_Management
144
COVER STORY: OXYGEN THERAPY
New Applications of Pulse
Frederic Michard
Founder & Managing
Director
MiCo
Oximetry
Switzerland
frederic.michard@bluewin.ch
michardfrederic
During and beyond the COVID-19 pandemic
www.michardconsulting.com/
P ulse oximetry was developed in the The clinical applications of pulse oximetry go far beyond the mere monitoring of
1970’s to monitor oxygen saturation SpO2. From home to ICUs, pulse oximeters may help to improve quality of care
(SpO2) during anaesthesia. It is today in patients with respiratory and circulatory disorders, in particular those with
a mainstay of perioperative and intensive the coronavirus disease 2019 (COVID-19).
care unit (ICU) monitoring, and is also
widely used in ambulances, emergency themselves, several remote monitoring cellphone (Michard et al. 2019). During
and respiratory departments. In this article, programmes have been created. They usually epidemics, remote monitoring also has
new applications of pulse oximetry are combine the use of a finger wireless sensor the advantage of decreasing the number
described, with a focus on patients with by the patient and a supervision by a of physical interactions and thereby the
coronavirus disease 2019 (COVID-19). dedicated and remote command centre risk of virus transmission.
Pulse oximetry is increasingly used for receiving SpO2 and pulse rate measurements In a large study done in the medico-
remote and self-monitoring of SpO2 from via the patient’s smartphone. In case of surgical wards of 360 US hospitals (Lyons
home, for continuous wireless monitoring abnormalities detected by the pulse oximeter, et al. 2020) before the pandemic, over
on hospital wards, and for controlling a dedicated staff is available to advise the 20% of rapid response interventions were
closed-loop oxygen administration systems. patient on a 24/7 basis. In addition to triggered by a decrease in SpO2. On the
In addition, tracking changes in the classical finger sensors using transmittance wards, vital sign spot-checks are usually
peripheral perfusion index (PI), a variable photoplethysmography, reflective sensors done every 4-8h and another study showed
derived from the pulse oximetry waveform, part of adhesive patches, wrist devices that because of the intermittent nature of
may help to detect tissue hypo-perfusion, or watches are now available (Figure 1). SpO2 measurements, nurses may miss up
as well as guide fluid management. In the In theory, these tools have potential to to 90% of hypoxaemic events (Sun et al.
future, pulse oximetry may also be useful expand the use of pulse oximetry. However, 2015). In this context, continuous pulse
to quantify respiratory efforts and to detect their accuracy remains to be established oximetry systems, able to inform nurses
changes in blood pressure. by well-designed clinical studies and most directly on their pager in case of clinical
have not been approved for medical use. deterioration, have been shown to be
Remote and Self-Monitoring of useful to decrease the number of rescue
SpO2 From Home Continuous Monitoring on Hospital interventions and ICU transfers. Continuous
Over the last decade, pulse oximeters Wards monitoring of SpO2 and other vital signs
have been miniaturised and have become The recent surge of hospitalised COVID- was already on the rise before the pandemic,
wireless. They also became affordable, 19 patients created both ICU bed and and is today, more than ever, considered
and several medical grade products can healthcare worker shortages, raising concerns as a major opportunity to improve patient
now be ordered online for less than €100. regarding patient safety. Therefore, the safety (Vincent et al. 2018).
As a result, pulse oximeters are more adoption of remote monitoring systems,
often part of our home medicine cabinet specifically designed for hospital wards, Automated oxygen administration
and the COVID-19 pandemic definitely dramatically increased. These systems In patients hospitalised for respiratory
boosted their adoption. Home monitoring enable the continuous monitoring of vital failure who require supplemental oxygen,
enables the early detection of patients signs, including SpO2, in a large number of precise manual oxygen titration is difficult to
requiring oxygen and hospitalisation, ward patients at the same time, display the achieve and is time-consuming. Automated
or the surveillance of patients after early information on a central station, and, in oxygen titration devices have been
discharge from the hospital (Shah et al. case of clinical deterioration, immediately developed to avoid periods of hypoxaemia
2020). For patients unable to monitor alert nurses directly on their pager or and hyperoxaemia (L’her et al. 2017).
ICU Management & Practice 3 - 2021145
COVER STORY: OXYGEN THERAPY
Tethered pulse oximeter Wireless pulse oximeter The evaluation of the capillary refill time is
intermittent and NIRS sensors are expensive.
Whether they have any advantages to guide
haemodynamic therapy over the mere and
continuous monitoring of PI with a pulse
oximeter remains to be demonstrated.
PPG Fluid Management
During general anaesthesia
Classical (transmittance) PPG In anaesthetised and mechanically
Reflectance PPG ventilated patients, the respiratory changes
signal
in left ventricular stroke volume induce
proportional changes in arterial pulse
pressure (PPV) and in PI, known as the
pleth variability index (PVI). PVI has been
shown to be a good predictor of fluid
responsiveness in the operating room, but
Smartphone Smartwatch not in the ICU where motion artifacts are
frequent, and the pulse oximetry signal
Adhesive e-patch is sometimes far to be optimal (as often
Figure 1. How to record a photoplethysmographic (PPG) waveform
evidenced by a low PI).
Because intra-operative PPV-guided
fluid therapy has been shown to decrease
These systems are based on a closed-loop low (146
COVER STORY: OXYGEN THERAPY
Figure 2. Examples of new medical devices using photoplethysmography (PPG). Left: modified Foley catheter with a PPG sensor enabling the continuous recording of the
urethral mucosal perfusion (from Vygon, with permission). Right: closed loop system adapting automatically oxygen flow to individual needs (from Oxynov, with permission).
postoperative outcome in high-risk ventilation, it is well established that What’s Next?
surgical patients (who usually have a radial both PPV and PVI have a poor predictive Quantifying respiratory efforts
catheter in place), it is unlikely that goal value, which is mainly related to a low The physiologic response to hypoxaemia
directed fluid therapy with non-invasive sensitivity. In contrast, the assessment is an increase in respiratory frequency and
methods may be cost-effective in low-risk of changes in cardiac output during a tidal volume. Work of breathing increases,
patients. passive leg raising (PLR) manoeuvre has resulting in large changes in pleural pressure
been shown to accurately predict preload which may be responsible for self-inflicted
In patients with acute respiratory failure responsiveness. This approach requires the acute lung injury. This phenomenon has
In patients with acute respiratory failure, use of cardiac output monitoring systems been advocated to explain, at least in part,
individualised fluid therapy is desirable to which are not always readily available the rapid deterioration of lung function in
balance the risks of fluid overload (increase or used, particularly in spontaneously severe COVID-19 patients. A recent study
in pulmonary oedema) with the risks breathing patients. Interestingly, the two (Tonelli et al. 2020) suggests that patients with
of fluid restriction (decrease in cardiac main determinants of the pulse oximetry- acute respiratory failure in whom respiratory
output and oxygen delivery to the tissues). derived PI are vascular tone and cardiac efforts do not quickly decrease after initiating
Predicting preload responsiveness is a output. Assuming no significant changes in non-invasive ventilation, ultimately require
way to identify patients who may benefit vascular tone, one may therefore assume that tracheal intubation. In research studies,
from fluid administration and, maybe changes in PI may reflect changes in cardiac respiratory efforts are quantified by monitoring
more importantly, to prevent unjustified output. A recent study done in critically ill the respiratory swings in oesophageal pressure.
fluid boluses in preload non-responders. patients showed that a relative increase in But in clinical practice, oesophageal probes are
Predicting preload responsiveness was PI >9% during a PLR manoeuvre predicts not used. In spontaneously breathing patients,
recently recommended by WHO, the an increase in cardiac output >10% with PVI depends mainly on the magnitude of
Surviving Sepsis Campaign guidelines a sensitivity of 91% and a specificity of changes in pleural pressure and could therefore
and the NIH for the fluid management 79% (Beurton et al. 2019). In summary, be used to approximate respiratory efforts
of COVID-19 patients. when cardiac output is not monitored, (Michard and Shelley 2020). Thus, when
In spontaneously breathing patients PLR-induced changes in PI may help to initiating oxygen therapy or non-invasive
and during protective mechanical predict fluid responsiveness. ventilation, monitoring changes in PVI may
ICU Management & Practice 3 - 2021147
COVER STORY: OXYGEN THERAPY
signs on hospital wards and closed-
Home loop administration of oxygen (Figure
3). In patients with acute respiratory
monitoring failure, tracking changes in PI during
Continuous a PLR manoeuvre may help to identify
Blood PR SpO2 monitoring on fluid non-responders and hence prevent
pressure ? AI PR
hospital wards
unjustified fluid administration. In
spontaneously breathing patients, a decrease
PWTT SpO2 in PVI may reflect a decrease in respiratory
PPG efforts. Therefore, monitoring PVI may help
signal to assess the efficacy of oxygen therapy,
PVI SpO2 CPAP or non-invasive ventilation. Changes
Fluid Closed-loop O2 in PWTT predict changes in blood pressure
∆PI
responsiveness PI admin. and could be used to trigger upper-arm
cuff measurements (automatic smart
Tissue perfusion ? triggering). Machine learning systems
have potential to extract more information
from pulse oximetry waveforms, and
such waveforms can now be recorded by
smartwatches or adhesive patches. These
innovations should further push the envelope
Figure 3. New and future applications of photoplethysmography (PPG)
PR, pulse rate; SpO2, oxygen saturation; PI, perfusion index; PVI, pleth variability index; PWTT, pulse wave transit
of photoplethysmography and create new
time; AI, artificial intelligence; admin., administration. opportunities for physiologic monitoring
beyond the operating room and the ICU.
help to assess the impact on respiratory (to detect cardiac contraction) and a finger
efforts and has potential to prevent intubation pulse oximeter, tracking changes in PWTT Conflict of Interest
delays. Clinical studies are currently ongoing has been used to unmask hypotensive events FM is the founder and managing director
to confirm these hypotheses. that, otherwise, would have been missed of MiCo (michardconsulting.com), a Swiss
by nurses who were spot-checking blood consulting and research firm. MiCo does
Tracking changes in blood pressure pressure only every 4h (Turan et al. 2019). not sell any medical device and FM does
Pulse oximeters can be used to calculate the More recently, a machine learning not receive royalties from any medical
pulse wave transit time (PWTT), which is the algorithm has been developed to predict device company.
time difference between cardiac contraction blood pressure from photoplethysmographic
References
and the peripheral pulse arrival. The PWTT waveforms (Ghamri et al. 2020). A large Beurton A, Teboul JL, Gavelli F et al. (2019) The effects of passive
depends on blood flow and the mechanical number of pulse oximetry waveforms and leg raising may be detected by the plethysmographic oxygen
saturation signal in critically ill patients. Crit Care, 23:19.
properties of the arterial bed. Both a decrease corresponding invasive blood pressure
Denault MH, Péloquin F, Lajoie AC, Lacasse Y (2019) Automatic
in cardiac output and in vascular tone numbers were used to “teach” the algorithm versus manual oxygen titration in patients requiring supplemental
(the two determinants of blood pressure) how to recognise specific patterns or oxygen in the hospital: A systematic review and meta-analysis.
Respiration, 98:178-188.
induce an increase in PWTT. Thus, tracking signatures of blood pressure changes
changes in PWTT has been proposed to (learning phase). During the validation Dépret F, Leone M, Duclos G et al. (2020) Monitoring tissue
perfusion: a pilot clinical feasibility study of a urethral photo-
predict changes in blood pressure. For phase, the algorithm demonstrated an plethysmography-derived perfusion device in high-risk patients.
J Clin Monit Comput, 34:961-9.
instance, continuous monitoring of PWTT excellent performance to detect changes in
has been shown to be useful to detect beat- arterial pressure during anaesthesia induction. Fischer MO, Lemoine S, Tavernier B et al. (2020) Individualized
fluid management using the pleth variability index: a randomized
to-beat changes in systolic arterial pressure clinical trial. Anesthesiology, 133:31-40.
during anaesthesia induction (Kim et al. Conclusion Fischer MO, Fiant AL, Debroczi S et al. (2020) Perioperative
2013). It could therefore be used to predict The surge of patients with COVID-19 non-invasive hemodynamic optimization using photo-
plethysmography: a randomized controlled trial and
hypotension and automatically trigger has been a catalyst for the adoption of meta-analysis. Anaesth Crit Care Pain Med., 39:421-8.
oscillometric brachial cuff measurements. SpO2 monitoring from home, remote
For full references, please email editorial@icu-management.org
In ward patients wearing wireless electrodes and continuous monitoring of vital or visit https://iii.hm/19z8
ICU Management & Practice 3 - 2021You can also read
