Agreement Between 5 Different Pulse Oximeters Used Simultaneously During a Six-minute Walk Test

51 patients will be included in this study , corresponding to an inclusion period of approximately 3 months.

Patients are all referred for an outpatient pulmonary rehabilitation program for which one or several six-minute walk test (6MWT) is standard procedure.

After the patient has given his/her consent and signed the consent form, they will be fitted with various pulse oximeter sensors (all CE certified and Bluetooth enabled):

• An ear sensor connected to the Nonin Wrist OX2 3150 pulse oximeter
• A flexible digital sensor connected to a Nonin Wrist OX2 3150 pulse oximeter
• A MightySat Rx digital pulse oximeter
• A rigid digital sensor connected to the Masimo Rad-G pulse oximeter
• A Nonin Vantage 9590 digital pulse oximeter from Onyx

The pulse oximeters are placed on the fingers of one hand (chosen according to patient comfort) and a lightweight shoulder strap is used to hold the arm against the abdomen in order to minimise any movement artefacts caused by arm swinging during walking. One of the oximeters is connected to a sensor placed on the earlobe . The last oximeter (Nonin Vantage 9590 from Onyx) is not equipped with Bluetooth transmission and cannot calculate the average or minimum SpO2. However, it is representative of the pulse oximeters commonly acquired and used by patients and caregivers. We will therefore record the results it gives at T0, T6, and at the end of the observation (it will be placed on the free hand).

The patient then receives standardised information about the six-minute walk test procedure (6MWT). The nurse or physiotherapist measures the patient's vital signs at rest: HR, BP, SpO2, dyspnoea on a modified Borg scale.

The 6MWT is then performed for 6 minutes in a marked 30-metre corridor, with standardised information provided every minute until the end of the test, in accordance with international recommendations. The patient is asked to walk at a pace that they think they can maintain for 6 minutes. If they experience excessive dyspnoea, they may sit down and resume the test as soon as they feel able to do so. The test is interrupted if SpO2 falls below 80% (on any of the pulse oximeters). Perceived breathlessness is recorded every minute. SpO2 and HR results are transmitted via Bluetooth to a tablet and can be monitored 'live'.

At the end of the test, the patient sits down and their vital signs are measured for another 2 minutes.

The data obtained during the test is then coded and transferred to an electronic case report form (eCRF) with a numerical code that does not refer to the patient's date of birth or initials.

A list of cases and their codes is kept in a password-protected Excel file, stored by a person outside the study staff.

Inclusion in the protocol takes place at most once per patient.

Inclusion criteria

• All patients referred to our Cardiorespiratory Unit for a pulmonary rehabilitation programme
• Aged over 18, no maximum age limit
• Absence of language barriers or cognitive impairments that would make it impossible to explain the protocol
• Resting SpO2 > 90%
• Signing the informed consent form after receiving detailed information about the study.

Exclusion criteria

• Any clinical condition that makes it impossible or compromises the performance of a walking test: unstable heart disease, acute myocarditis and/or pericarditis, acute arrhythmia, severe pulmonary hypertension, deep vein thrombosis, severe asthma, acute orthopaedic or rheumatic condition
• Unstable clinical condition (patient hospitalised or less than 4 weeks after an exacerbation leading to hospitalisation)
• Oxygen therapy at rest and/or during walking
• Uncontrolled arterial hypertension (AHT) at rest
• Known cardiac rhythm disorder
• Unexplained chest pain at rest
• Mechanical interference with the possibility of placing pulse oximeters: skin lesions, bandages, plaster casts, etc.
• Withdrawal of consent during the study
• Systemic scleroderma, sclerodactyly, history of any type of vasculitis
• Symptomatic Raynaud's phenomenon
• Marked clubbing
• Known haemoglobinopathy
• Refusal to remove nail polish