Clinical trial NCT03395782: Factors Determining Oxygen Wash in During Pre-oxygenation
Official title: Factors Determining End-tidal O2 Concentration in During Pre-oxygenation
Study type: OBSERVATIONAL
Overall status: COMPLETED
Conditions: Airway Complication of Anesthesia
Lead sponsor: Region Västmanland
Sponsor class: OTHER
First posted: 2018-01-10
Enrollment: 120
Sex: ALL
Minimum age (years): 40
Maximum age (years): 79
Standard ages: ADULT
OLDER_ADULT
Observational model: COHORT
Time perspective: PROSPECTIVE
Sampling method: NON_PROBABILITY_SAMPLE
Study population: Patients scheduled for elective surgery in general anaesthesia.

Brief summary: Earlier studies has shown a correlation between older age and longer time for the rise in the end-tidal O2 concentration during pre-oxygenation. In this study the investigators aim to analyse this correlation more closely and investigate if the arterial partial pressure of oxygen (PaO2) as measured before the start of pre-oxygenation, with the patient breathing air, is a better predictor than age for estimating the time necessary for achieving the goal of pre-oxygenation.

Detailed description: Before induction of general anaesthesia pre-oxygenation is a recommended procedure to enhance the time available for solving a problem with the airway or intubation during induction. This can be accomplished by letting the patient breath normal tidal volumes with 100% oxygen for 3 to 5 minutes during pre-oxygenation. If there is airway closure during tidal volume breathing, pre-oxygenation needs longer time to achieve a maximum effect. Airway closure increases with advanced age and a few earlier studies has also shown a correlation between older age and longer time for the rise in the end-tidal O2 concentration during pre-oxygenation.

Pre-oxygenation is a strongly recommended safety procedure before starting anaesthesia but has at least one major side affect: it is the main reason for the development of atelectasis in the lungs during anaesthesia. Atelectasis impairs oxygenation during anaesthesia and probably increase the risk for postoperative pulmonary complications.

Postoperative complications are more common with advanced age and it is important to understand the mechanisms and risk factors involved.

In this study, the investigators hypothesise that the PaO2 as measured before the start of pre-oxygenation, with the patient breathing air, is a better predictor than age for estimating the time necessary for achieving the goal of pre-oxygenation. If this assumption is correct it might have implication for how pre-oxygenation should be adjusted with advancing age.

Eligibility criteria: Inclusion Criteria:

* Patients scheduled for general anaesthesia in American Society of Anesthesiology (ASA) physical status classification grade I-III.
* Body mass index over 18.5 and less than 30 kg/m2
* Peripheral oxygen saturation 92% or more on air.

Exclusion Criteria:

* ASA IV.
* Patients with active smoking and former smokers with a history of smoking more than 6 pack-years.
* Chronic obstructive lung disease.
* Bloodgas with PaO2 ≤ 8 kilopascal (kPa) or PaCO2 ≥ 6.5 kPa.
* Continuous positive airway pressure treatment at night.
* Heart failure or angina pectoris.
* Hemoglobin value less than 100 g/L.
* Pregnancy.
* Any neuromuscular or neurologic illness reducing ventilatory capacity.
* Any endocrine disease influencing basic metabolic demand.
* Not possible to achieve a tight mask seal.
* Patient unable to follow instructions.

Primary outcomes:
measure: PaO2 breathing air before start of pre-oxygenation and the rise in end-tidal O2 during pre-oxygenation.
timeFrame: 5 minutes.
Secondary outcomes:
measure: Age and the rise in end-tidal O2 during pre-oxygenation.
timeFrame: 5 minutes.
Other outcomes:
Locations:
city: Köping
country: Sweden
facility: Köping County Hospital
state: Västmanland
Study officials:
affiliation: Region Västmanland
name: Lennart Edmark, Ph.D.
role: PRINCIPAL_INVESTIGATOR
References:
citation: Kang H, Park HJ, Baek SK, Choi J, Park SJ. Effects of preoxygenation with the three minutes tidal volume breathing technique in the elderly. Korean J Anesthesiol. 2010 Apr;58(4):369-73. doi: 10.4097/kjae.2010.58.4.369. Epub 2010 Apr 28.
citation: Sum Ping SJ, Makary LF, Van Hal MD. Factors influencing oxygen store during denitrogenation in the healthy patient. J Clin Anesth. 2009 May;21(3):183-9. doi: 10.1016/j.jclinane.2008.07.004.
citation: Milic-Emili J, Torchio R, D'Angelo E. Closing volume: a reappraisal (1967-2007). Eur J Appl Physiol. 2007 Apr;99(6):567-83. doi: 10.1007/s00421-006-0389-0. Epub 2007 Jan 20.
citation: Gambee AM, Hertzka RE, Fisher DM. Preoxygenation techniques: comparison of three minutes and four breaths. Anesth Analg. 1987 May;66(5):468-70. No abstract available.