An observational study measuring respiratory rate as assessed by respiR8® in post operative patients aged 60 years and above

Background
Clinically significant respiratory depression post-operatively remains a
serious patient safety risk and respiratory rate is one vital sign that gives
an early indication of patient deterioration. However, respiratory rate is
often not measured continuously and it is difficult to measure accurately. It
is recognised that intermittent spot checks are not adequate for reliably
recognising clinically significant respiratory changes in the postoperative
period. , Continuous quality improvement in electronic monitoring is sought
based on an increased likely risk to miss respiratory depression in patients.
This monitoring would benefit from being from a central location, with
information being reliably transmitted to the healthcare professional
minimising the failure of caregivers to recognise respiratory depression.
Current clinical practice for measurement of respiratory rate in post-operative
recovery is predominantly a manual method with Healthcare Professionals (HCPs)
periodically counting chest excursions. Respiratory rate can be recorded from
ECG monitor detection of chest excursions. Chest excursion counts can,
however, be misleading as these counts may indicate respiratory rate but do not
confirm gas movement into and out of the lungs as in the instance of an upper
airway obstruction, thus not detecting obstructive apnoeas.
The experience from the use of respiR8® in post-operative recovery has shown
that respiratory rate often falls below 6 breaths per minute and periods of
apnoea are detected. Falls in respiratory rate to 6 breaths per minute or
below have been noted when patients are sleeping and respiratory depression
alarms have alerted nurses as much as 2 hours earlier than oxygen saturation
alarms.
Respiratory depression measured by episodes of desaturation versus incidence of
bradypnoea demonstrates 41% patients having bradypnoea and only 12% patients
displaying a desaturation event. This further supports the view that pulse
oximetry may be a late indicator of hypoventilation.
Oxygen saturation levels as measured by pulse oximetry do fall to below 95% in
spite of the patient being given supplemental oxygen. Pulse oximetry is
frequently used in post-operative care as a means of measuring for adequate
ventilation but is not a replacement for respiratory rate measurement being a
late sign of clinical deterioration. , When supplemental oxygen is
administered blood oxygen saturation levels are slow to respond, even when the
patient ceases breathing. In this instance an automated, non-intrusive
respiratory rate counter such as the respiR8® could provide valuable support to
health care staff.

Rationale for this study
Monitoring systems can both detect and predict patient deterioration.
Predictive systems do not require continuous data collection for patients to be
selected for higher levels of care.i The primary function of detective systems
is to identify and report deterioration. For this study the respiR8® will
generate continuous visual data and not continuous automated print out data.
Irregular breathing patterns as signatures of clinical changes occurring will
alert that a patient is becoming apnoeic and will enable an intervention and
safety net to be available where it might have otherwise been missed.

Respiratory rate, normally described in breaths per minute is between 12 and 18
breaths per minute for a normal adult. Nurse awareness of eupnoea (normal rate
and depth), bradypnoea (abnormally slow respiration), tachypnoea (abnormally
fast respirations) and apnoea (cessation or absence of breathing) is essential
for post-operative patient care.

This study is a precursor to investigating correlations between respiratory
complications and cognitive dysfunction in o¬¬¬¬¬lder patients. In the older
population, duration of anaesthesia and respiratory complications are risk
factors for post-operative delirium and early cognitive dysfunction , In 1200
patients of more than 60 years of age an incidence of post-operative cognitive
dysfunction (POCD) of ~25% at 1 week and 10% at 3 months post-operatively and
~1% up to 2 years after the operation . There is significant association
between increasing POCD and respiratory complications, therefore attention is
needed to minimise and avoid respiratory complications where possible.
The respiR8® monitors patients within the post-operative setting and could be
used as a system for continuous, automated monitoring of patients ensuring that
any excursion into an abnormal respiration rate is able to be detected and
acted upon by medical staff.
The respiR8® is approved for sale in Europe (CE marked).

Primary objective
• To estimate the frequency of subjects with at least one apnoeic episode,
defined as respiratory rate <=6, detected using the respiR8® device for up to 6
hours after surgery. Apnoea is defined as 10 seconds of no breathing activity
or a respiratory rate <=6 of undefined duration.

Secondary objectives
The secondary objectives are:
• To estimate the frequency of subjects with multiple apnoeic episodes detected
using the respiR8® device. Episodes of apnoea will be separated by episodes of
non-apnoeic breathing.
• To estimate frequency of respiratory rate abnormalities. Tachypnoea ( >=18
breaths per minute for at least 20 seconds) and bradypnoea ( <= 10 breaths per
minute for at least 20 seconds).
• To estimate the level of association between the respiratory rate from the
respiR8® device and oxygen saturation levels.
• To study the distribution of respiR8® respiratory rate values over time.
• To study the distribution of saturation of peripheral oxygen SpO2 levels over
time.
• To study episodes of oxygen desaturation of <=94%.
• To investigate frequency of actions and interventions taken by clinical
staff, frequency of the respiR8® mask being removed from patients face with
reasons.

Observational and open

The burden to the patient is minimal.