The Operating Theatre Journal - Journal - Page 10
How to THRIVE in the Operating Theatre
It could be argued, in recent years few other changes in practice or
adoptions of new techniques have the potential to positively impact
patient safety and outcomes in the operating theatre, more than
the THRIVE technique. This novel use of an established ‘ward based’
respiratory therapy, High Flow Oxygen Therapy (HFOT), applied to
the theatre setting has gained a foothold across numerous hospitals in
European countries, and beyond, with many now using it as standard
practice for preoxygenation and safer intubation. In this blog we will
bring it back to basics. What is the THRIVE technique? How does it
work? Why would you consider using it?
Let’s break it down…
The acronym is always a good place to start. THRIVE stands for
Transnasal Humidified Rapid-Insufflation Ventilatory Exchange and was
first coined in the UK by Patel and Nouraei during a study conducted
by the pair between 2013 and 2014 [1]. As the name suggests, the
technique is delivered to a patient via the nasal passages (Transnasal)
using specialist equipment. It utilises oxygen rich gases, that have been
heated and had water vapour added to ‘optimally condition’ them
(Humidified), blown into the upper airways at flow rates in excess of
45L/pm (Rapid-Insufflation). These humidified gases are then used to
oxygenate a patient during apnoea following induction of anaesthesia
(Ventilatory Exchange).
Originally used in the acute care ward setting, high flow rates of
respiratory gas, at a prescribed and set FiO2, have been shown to
aid in the treatment of patients with hypoxaemia. The easy to fit and
operate equipment [Image 1 & 2] has made strides in the treatment of
patients with Type 1 respiratory failure, bridging the gap between low
flow oxygen and CPAP therapies and is widely referred to as High Flow
Oxygen Therapy (HFOT) [2]. The development of the THRIVE technique,
using HFOT, has therefore paved the way for the diversification of this
therapy into alternative hospital departments. In the theatre setting it
not only enables the use of the THRIVE technique but also demonstrates
additional benefits that may be useful throughout the perioperative
journey.
accurate FiO2 delivery, reduced inspiratory work of breathing, variable
PEEP effect, improved mucociliary clearance and patient comfort and
the ability to deliver apnoeic oxygenation [4,5].
In turn, each of these benefits may have a positive impact directly
in the operating theatre environment. The improvement in alveolar
ventilation, because of the reduced anatomical dead space in the
upper airways, helps contribute to better preoxygenation due to the
increased volume of O2 available in the alveoli for gaseous exchange
[3]. Accurate FiO2 delivery, through less dilution of inspired gases
due to reduced CO2 rebreathing from the anatomical dead space and
diminished entrainment of room air, creates a greater concentration of
O2 in the alveoli contributing to better preoxygenation [3].
Reduced inspiratory work of breathing is useful in post-op recovery to
help ensure adequate oxygenation and recovery in a situation where
respiratory effort may not be optimal. The variable PEEP effect,
generated by the patient’s expiratory breath having to pass through
partially occluded nares against oncoming gas flow [6], may also be
useful in post-op recovery to recruit alveoli in patients suffering from
post-op atelectasis and during preoxygenation in patients who have
existing atelectasis, ensuring full lung patency for enhanced gaseous
exchange. The heating and addition of water vapour to the respiratory
gases used in HFOT helps improve mucociliary clearance and patient
comfort [7].
The theatre environment being normally colder than ward can impact
normothermia. Having a heated therapy, especially in recovery, can
help the patient return to normothermia more quickly. The ability of
HFOT to deliver apnoeic oxygenation is where the THRIVE technique
comes into play. By utilising a physiological phenomenon known as
Aventilatory Mass Flow (AVMF), HFOT can be used in theatre to extend
the time a patient remains within normal oxygen saturation range while
apnoeic [1].
Aventilatory Mass Flow (AVMF)
This Aventilatory Mass Flow (AVMF) [8] phenomenon, present during
the THRIVE technique, allows for extended apnoea time within a safe
oxygen saturation range. The fresh gas reservoir created by HFOT
ensures constant availability of oxygen in the upper airways that
is drawn into the lung due to the negative pressure gradient that
develops in the lower airways during apnoea [1,9]. With the rate of O2
removal from the alveoli into the blood capillaries unchanged following
induction of apnoea, the reduced CO2 excretion that occurs results
in a generation of the negative pressure due to lack of ventilatory
movement [8,9]. As long as the patient’s airway remains open, a
pathway exists to atmosphere and the pressure gradient draws O2 from
the fresh gas reservoir [10].
Conclusion
Using the THRIVE technique and AVMF allows for continual oxygenation
of a patient for lengths of time far exceeding the standard apnoeic
window. It has been shown to extend safe apnoea time up to 65 minutes
[1] opening the door to tubeless operations, especially beneficial in ENT
surgery and biopsies. The benefits to the theatre department in terms
of increased patient safety and throughput of cases are just some of
the positive impacts the introduction of HFOT to deliver THRIVE can
present. Further exploration for individual needs may be required but
certainly even the benefit of improved and effective preoxygenation
will transpire across the hospital with additional benefits applying in
most cases.
Further reading: https://www.armstrongmedical.net/blog/
HFOT delivered via AquaVENT® FD140i
References
[1]
[2]
HFOT delievered via POINT® blender
So, what does HFOT do that makes it particularly useful
in the theatre setting?
[3]
HFOT works by washing out the upper airways and generating a
humidified fresh gas reservoir that leads to multiple benefits for the
patient. This ‘nasopharyngeal dead space washout’ is achieved by
the high flows of gas being delivered directly into the upper airway
from the purpose-built high flow nasal cannula [3]. The oxygen rich
gas displaces waste gases normally found in the nasopharyngeal area
and replaces them with constantly refreshed gases delivered at the
set FiO2. Benefits to patient include improved alveolar ventilation,
[5]
10
[4]
[6]
[7]
[8]
[9]
[10]
Patel, A., and SA Reza Nouraei. “Transnasal Humidified Rapid-Insufflation Ventilatory Exchange (THRIVE):
a physiological method of increasing apnoea time in patients with difficult airways.” Anaesthesia 70.3
(2015): 323-329.
Rochwerg, B., et al. “High flow nasal cannula compared with conventional oxygen therapy for acute
hypoxemic respiratory failure: a systematic review and meta-analysis.” Intensive care medicine 45 (2019):
563-572.
Dysart, Kevin, et al. “Research in high flow therapy: mechanisms of action.” Respiratory medicine 103.10
(2009): 1400-1405.
Nishimura, Masaji. “High-flow nasal cannula oxygen therapy in adults: physiological benefits, indication,
clinical benefits, and adverse effects.” Respiratory care 61.4 (2016): 529-541.
Masclans, J. R., P. Pérez-Terán, and O. Roca. “The role of high-flow oxygen therapy in acute respiratory
failure.” Medicina Intensiva (English Edition) 39.8 (2015): 505-515.
Sun, Yu-Han, et al. “Factors affecting FiO2 and PEEP during high-flow nasal cannula oxygen therapy: A
bench study.” The Clinical Respiratory Journal 13.12 (2019): 758-764.
Schulze, Andreas. “Respiratory gas conditioning and humidification.” Clinics in perinatology 34.1 (2007):
19-33.
Bartlett Jr, R. G., H. F. Brubach, and H. Specht. “Demonstration of aventilatory mass flow during
ventilation and apnea in man.” Journal of Applied Physiology 14.1 (1959): 97-101.
Nouraei, Reza, et al. “What is transnasal humidified rapid-insufflation ventilatory exchange (THRIVE).”
ENT and Audiology news 27 (2018): 1-4.
MH, HOLMDAHL. “Pulmonary uptake of oxygen, acid-base metabolism, and circulation during prolonged
apnoea.” Acta Chirurgica Scandinavica. Supplementum 212 (1956): 1-128.
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