Clinical trial NCT00673634: Efficiency of Preoxygenation in Obese Patients: Pressure Assisted Versus Traditional Method
Official title: Efficiency of Preoxygenation in Obese Patients: Evaluation of Traditional Method Versus Pressure Assisted Preoxygenation.
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Obesity
Keywords: preoxygenation
method
efficiency
obesity
BiPAP
FeO2
Lead sponsor: Maisonneuve-Rosemont Hospital
Sponsor class: OTHER
First posted: 2008-05-07
Enrollment: 30
Sex: ALL
Minimum age (years): 18
Maximum age (years): 75
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Primary purpose: PREVENTION

Brief summary: The purpose of this clinical trial is to evaluate whether pre-oxygenation of obese patients with BiPAP 4cm H2O, renders any benefit to the quality of pre-oxygenation measured by the expired oxygen fraction (FeO2) and whether it is as well tolerated as the traditional method of spontaneous breathing for 3 minutes.

Detailed description: Traditional pre-oxygenation in obese patients has been proven to allow a time of apnea far reduced when compared with patients closer to their ideal body weight. This effect is attributable to several factors :

* Reduced FRC
* Increased closing capacity
* Diminished tidal volume due to increased resistance of the airway, diminished compliance of the thoracic cage and diminished strength and endurance of respiratory muscles.
* Increase in atelectasis formation upon induction of general anaesthesia.
* Increased O2 consumption due to the increased workload of respiratory muscles and to the general increase in metabolism.
* Increase in true shunt. Studies have demonstrated a reduction in atelectasis formation by application of CPAP during pre-oxygenation and PEEP during anaesthesia. Also, 25º inclination of the patient in the supine position, on the operating table, has demonstrated prolongation of time of apnea in a significant amount. Outside the operating room, PEEP of 5 cmH2O has been demonstrated useful in prolonging time of apnea when used during pre-oxygenation in hypoxic patients requiring tracheal intubation in the intensive care.

Yet, few studies have evaluated BiPAP in the operating room setting as to the effect on FeO2 and to the tolerance by the patients.

Thus, it is our intent to evaluate the efficiency of application of an inspiratory assistance pressure of 4cmH2O and PEEP 4cmH2O during a 3 minutes pre-oxygenation trial as to the level of FeO2 attained, the rate of attainment of FeO2 \> 90% and the tolerance by the patient of the procedure, when compared with a 3 minute trial of the traditional method.

For this purpose, consenting, non pre-medicated obese patients scheduled for surgery in the operating ward of our institution will be brought earlier to the operating room, the day of their surgery. In an idle operating room, they will go through two trials of 100% O2 pre-oxygenation lasting 3 minutes each, at an interval of 20 minutes during which the patients will rest in a semi-sitting position, breathing spontaneously at ambient air. The order of the two trials will be randomly assigned between standard pre-oxygenation vs BiPAP pre-oxygenation. Both patients and anesthesia assistants providing the pre-oxygenation will be blinded as to the ongoing trial. Data from the anesthesia machine will be recorded visually to be analysed subsequently by a blinded third party. During each trial, the comfort of the patient on a local 4 point scale will be graded every minute.

At the end of the study period, patients will be returned to the waiting area of the operating ward before the scheduled time of their surgery. The protocol is intended to not interfere with the planned anesthesia technique or the surgery in any way.

Eligibility criteria: Inclusion Criteria:

* BMI \> 30
* Scheduled for surgery

Exclusion Criteria:

* Non fasted patient
* Clinically significant gastro-oesophageal reflux
* Intestinal occlusion
* Presence of nasogastric tube
* Facial hair
* Claustrophobia

Primary outcomes:
measure: rate of increase of fractional expired oxygen level
timeFrame: every 10 seconds during each 3 minute preoxygenation period
Secondary outcomes:
measure: Level of fractional expired oxygen. Patient tolerance. Ease of preoxygenation administration. Presence of secondary effects (gastric reflux, respiratory discomfort, burps)
timeFrame: every minute during each 3 minute preoxygenation trial and at the end of each trial
Other outcomes:
Locations:
city: Montreal
country: Canada
facility: Maisonneuve-Rosemont Hospital
state: Quebec
Study officials:
affiliation: Maisonneuve-Rosemont Hospital
name: Pierre Drolet, MD, FRCPC
role: STUDY_DIRECTOR
affiliation: Maisonneuve-Rosemont Hospital / Université de Montréal
name: Mihai L Georgescu, MD, resident
role: PRINCIPAL_INVESTIGATOR
References:
citation: HAMILTON WK, EASTWOOD DW. A study of denitrogenation with some inhalation anesthetic systems. Anesthesiology. 1955 Nov;16(6):861-7. doi: 10.1097/00000542-195511000-00004. No abstract available.
citation: Campbell IT, Beatty PC. Monitoring preoxygenation. Br J Anaesth. 1994 Jan;72(1):3-4. doi: 10.1093/bja/72.1.3. No abstract available.
citation: Dixon BJ, Dixon JB, Carden JR, Burn AJ, Schachter LM, Playfair JM, Laurie CP, O'Brien PE. Preoxygenation is more effective in the 25 degrees head-up position than in the supine position in severely obese patients: a randomized controlled study. Anesthesiology. 2005 Jun;102(6):1110-5; discussion 5A. doi: 10.1097/00000542-200506000-00009.
citation: Wax DB. Mechanism of benefit of head-up preoxygenation in obese patients. Anesthesiology. 2006 Feb;104(2):381; author reply 381. doi: 10.1097/00000542-200602000-00035. No abstract available.
citation: Pelosi P, Ravagnan I, Giurati G, Panigada M, Bottino N, Tredici S, Eccher G, Gattinoni L. Positive end-expiratory pressure improves respiratory function in obese but not in normal subjects during anesthesia and paralysis. Anesthesiology. 1999 Nov;91(5):1221-31. doi: 10.1097/00000542-199911000-00011.
citation: Parameswaran K, Todd DC, Soth M. Altered respiratory physiology in obesity. Can Respir J. 2006 May-Jun;13(4):203-10. doi: 10.1155/2006/834786.
citation: Jense HG, Dubin SA, Silverstein PI, O'Leary-Escolas U. Effect of obesity on safe duration of apnea in anesthetized humans. Anesth Analg. 1991 Jan;72(1):89-93. doi: 10.1213/00000539-199101000-00016.
citation: Goldberg ME, Norris MC, Larijani GE, Marr AT, Seltzer JL. Preoxygenation in the morbidly obese: a comparison of two techniques. Anesth Analg. 1989 Apr;68(4):520-2. No abstract available.
citation: Coussa M, Proietti S, Schnyder P, Frascarolo P, Suter M, Spahn DR, Magnusson L. Prevention of atelectasis formation during the induction of general anesthesia in morbidly obese patients. Anesth Analg. 2004 May;98(5):1491-5, table of contents. doi: 10.1213/01.ane.0000111743.61132.99.
citation: Eichenberger A, Proietti S, Wicky S, Frascarolo P, Suter M, Spahn DR, Magnusson L. Morbid obesity and postoperative pulmonary atelectasis: an underestimated problem. Anesth Analg. 2002 Dec;95(6):1788-92, table of contents. doi: 10.1097/00000539-200212000-00060.
citation: Rose DK, Cohen MM. The airway: problems and predictions in 18,500 patients. Can J Anaesth. 1994 May;41(5 Pt 1):372-83. doi: 10.1007/BF03009858.
citation: Gagnon C, Fortier LP, Donati F. When a leak is unavoidable, preoxygenation is equally ineffective with vital capacity or tidal volume breathing. Can J Anaesth. 2006 Jan;53(1):86-91. doi: 10.1007/BF03021532.
citation: Ho-Tai LM, Devitt JH, Noel AG, O'Donnell MP. Gas leak and gastric insufflation during controlled ventilation: face mask versus laryngeal mask airway. Can J Anaesth. 1998 Mar;45(3):206-11. doi: 10.1007/BF03012903.
citation: Baillard C, Fosse JP, Sebbane M, Chanques G, Vincent F, Courouble P, Cohen Y, Eledjam JJ, Adnet F, Jaber S. Noninvasive ventilation improves preoxygenation before intubation of hypoxic patients. Am J Respir Crit Care Med. 2006 Jul 15;174(2):171-7. doi: 10.1164/rccm.200509-1507OC. Epub 2006 Apr 20.
citation: Berthoud MC, Peacock JE, Reilly CS. Effectiveness of preoxygenation in morbidly obese patients. Br J Anaesth. 1991 Oct;67(4):464-6. doi: 10.1093/bja/67.4.464.
citation: Kashyap L, Yaddanapudi LN, Sandhya. Arterial desaturation during induction with and without preoxygenation: evaluation of four techniques. Anaesth Intensive Care. 1993 Dec;21(6):811-3. doi: 10.1177/0310057X9302100611.
citation: Rapaport S, Joannes-Boyau O, Bazin R, Janvier G. [Comparison of eight deep breaths and tidal volume breathing preoxygenation techniques in morbid obese patients]. Ann Fr Anesth Reanim. 2004 Dec;23(12):1155-9. doi: 10.1016/j.annfar.2004.10.012. French.