Brazilian Journal of Anesthesiology
https://bjan-sba.org/article/doi/10.1590/S0034-70942005000500004
Brazilian Journal of Anesthesiology
Scientific Article

Impacto do acoplamento de máscara facial sobre a oxigenação

Oxygenation: the impact of face mask coupling

Waldemar Montoya de Gregori; Lígia Andrade da Silva Telles Mathias; Luiz Piccinini Filho; Ernesto Leonardo de Carpio Pena; Aníbal Heberto Mora Vicuna; Joaquim Edson Vieira

http://dx.doi.org/10.1590/S0034-70942005000500004 Braz J Anesthesiol, vol.55, n5, p.500-507, 2005
PDF Português
PDF English
Downloads: 0
Views: 1022

Resumo

JUSTIFICATIVA E OBJETIVOS: As diferentes técnicas de oxigenação existentes têm o objetivo de produzir desnitrogenização prévia ao período de apnéia durante a indução. A principal razão em que a concentração inspirada de oxigênio (CIO2) não atinge 100% é a falta de acoplamento adequado da máscara facial, permitindo a entrada de ar ambiente. Embora os anestesiologistas conheçam este princípio, nem todos o aplicam corretamente, facilitando a entrada de ar no fluxo de gases frescos (FGF) e, conseqüentemente, diluindo a CIO2. Este estudo procurou avaliar comparativamente, através da variação da CEO2, (concentração expirada de O2), a eficácia da técnica de oxigenação com máscara facial, nas condições habitualmente empregadas pelos anestesiologistas, simulando situações de vazamentos progressivos. MÉTODO: Foram estudadas as CEO2 de 15 voluntários, estado físico ASA I, submetidos à técnica de oxigenação com oito respirações profundas (capacidade vital) em 60s com fluxo de gás fresco de 10 L.min-¹. A máscara facial foi bem acoplada com CIO2 de 100% (Ac100), ou variando de 50% a 90% (Ac50; Ac60; Ac70; Ac80; Ac90); máscara acoplada pela gravidade e CIO(2)100% (Grav) e máscara a 1 cm da face e CIO2 a 100% (Afast). A CEO2 foi registrada em intervalos de 10s até 60s. Nos testes estatísticos p < 0,05 foi considerado significativo. RESULTADOS: A CEO2 aumentou em todos os grupos (p < 0,001), mas somente o grupo Ac100 atingiu valores próximos do ideal (82,20 - 87). Comparando-se as CEO2 atingidas no final de 60s, observou-se diferença estatística significativa entre as técnicas Ac100 e Grav (82,20 e 65,87), mostrando que a utilização da máscara acoplada apenas pela gravidade não produziu oxigenação adequada. Não houve diferença significativa entre os grupos Grav e Ac70 (65,87 e 62,67) em todos momentos estudados, sugerindo que a técnica do acoplamento pela gravidade simula aos 60s, uma CIO2 de 70%. A CEO2 média do grupo Afast atingiu valor de 47,20, que mostra que essa técnica pode ser associada a risco inaceitável de hipoxemia. CONCLUSÕES: Houve aumento progressivo da CEO2 em todos os grupos estudados, embora com redução da eficácia da técnica de oxigenação devida às várias situações de não acoplamento adequado. Este estudo mostrou, assim, a importância da atenção ao momento da oxigenação, utilizando-se a máscara bem acoplada, eliminando-se as condutas habituais de máscara afastada ou acoplada pela gravidade.

Palavras-chave

EQUIPAMENTOS, GASES, VENTILAÇÃO

Abstract

BACKGROUND AND OBJECTIVES: Different oxygenation techniques aim at promoting denitrogenation before apnea during induction. The main reason why CIO2 = 100% cannot be reached is the lack of adequate face mask coupling, allowing the entry of room air. Although anesthesiologists know this principle, not all of them apply it correctly, facilitating the entry of air in fresh gases flow and consequently diluting CIO2. This prospective study was performed to comparatively evaluate, through the variation of oxygen expired concentration (CEO2), the efficacy of the oxygenation technique via face mask in the conditions routinely used by anesthesiologists, simulating situations of progressive leaks. METHODS: Oxygen end-tidal concentrations of 15 volunteers, physical status ASA I, were studied with 8 deep breaths (vital capacity) in 60 s with fresh gas flow of 10 L.min-1. The face mask was: tightly fitted with 100% CIO2 (Tf100) or varying from 50% to 90%, (Tf50, Tf60, Tf70, Tf80, Tf90); gravity-coupled to face and 100% CIO2 (Grav) and moved 1 cm away from face with 100% CIO2 (Aw). CEO2 was recorded at 10 s intervals. P < 0.05 was considered statistically significant. RESULTS: CEO2 has increased for all groups (p < 0.001), but only Tf100 reached values close to ideal (82.20 - 87). Comparing mean CEO2 of Grav and Tf100 at the end of 60s, (82.20 and 65.87) there was a difference of approximately 20% between both techniques, since gravity-coupled mask only did not provide adequate oxygenation. There were no significant differences between groups Tf70 and Grav (65.87 and 62.67) in all studied moments, suggesting that the latter simulates a 70% CIO2 at 60 s. Mean Aw group CEO2 increased to 47.20 at 60s showing that this technique may be associated to unacceptable risk of hypoxemia. CONCLUSIONS: All situations of face mask coupling gradually increased CEO2, although with decreased oxygenation efficacy due to situations of face mask malposition. This study has shown the need for attention during oxygenation, using well coupled face mask and eliminating normal practices of moved away or gravity-coupled masks.

Keywords

EQUIPMENTS, GASES, VENTILATION

References

Campbell IT, Beatty PC. Monitoring pre-oxygenation. Br J Anaesth. 1994;72:3-4.

, . Preoxygenation: physiology and practice. Lancet. 1992;339:31-32.

Baraka AS, Taha SK, El-Khatib MF. Oxygenation using tidal volume breathing after maximal exhalation. Anesth Analg. 2003;97:1533-1535.

Berry CB, Myles PS. Preoxygenation in healthy volunteers: a graph of oxygen "washin" using end-tidal oxygraphy. Br J Anaesth. 1994;72:116-118.

McGowan P, Skinner A. Preoxygenation-the importance of a good face mask seal. Br J Anaesth. 1995;75:777-778.

Warden JC. Accidental intubation of the oesophagus and preoxygenation. Anaesth Intensive Care. 1980;8:377.

Kung MC, Hung CT, Lam A. Arterial desaturation during induction in healthy adults: should preoxygenation be a routine?. Anaesth Intensive Care. 1991;19:192-196.

Schlack W, Heck Z, Lorenz C. Mask tolerance and preoxygenation: a problem for anesthesiologists but not for patients. Anesthesiology. 2001;94.

Dillon JB, Darsie ML. Oxygen for acute respiratory depression due to administration of thiopental sodium. J Am Med Assoc. 1955;159:1114-1116.

Hamilton WK, Eastwood DW. A study of denitrogenization with some inhalation anesthetic systems. Anesthesiology. 1955;16:861-867.

Gold M, Duarte I, Muravchick S. Arterial oxygenation in conscious patients after 5 minutes and after 30 seconds of oxygen breathing. Anesth Analg. 1981;60:313-315.

Nimmagadda U, Chiravuri SD, Salem MR. Preoxygenation with tidal volume and deep breathing techniques: the impact of duration of breathing and fresh gas flow. Anesth Analg. 2001;92:1337-1341.

Norris MC, Dewan DM. Preoxygenation for cesarean section: a comparison of two techniques. Anesthesiology. 1985;62:827-829.

Goldberg ME, Norris MC, Larijani GE. Preoxygenation in the morbidly obese: a comparison of two techniques. Anesth Analg. 1989;68:520-522.

Baraka A, Taha S, Aouad M. Preoxygenation: comparison of maximal breathing and tidal volume breathing techniques. Anesthesiology. 1999;91:612-616.

Valentine SJ, Marjot R, Monk CR. Preoxygenation in the elderly: a comparison of the four-maximal-breath and three-minute techniques. Anesth Analg. 1990;71:516-519.

Bhatia PK, Bhandari SC, Tulsiani KL. End-tidal oxygraphy and safe duration of apnoea in young adults and elderly patients. Anaesthesia. 1997;52:175-178.

Nimmagadda U, Salem MR, Joseph NJ. Efficacy of preoxygenation with tidal volume breathing. Comparison of breathing systems. Anesthesiology. 2000;93:693-698.

Benumof JL. Preoxygenation: best method for both efficacy and efficiency?. Anesthesiology. 1999;91:603-605.

Berthoud M, Read DH, Norman J. Pre-oxygenation: how long?. Anaesthesia. 1983;38:96-102.

Drummond GB, Park GR. Arterial oxygen saturation before intubation of the trachea. An assessment of oxygenation. Br J Anaesth. 1984;56:987-993.

Russell GN, Smith CL, Snowdon SL. Pre-oxygenation and the parturient patient. Anaesthesia. 1987;42:346-351.

Duda D, Brandt L, Rudlof B. Effect of different pre-oxygenation procedures on arterial oxygen status. Anaesthesist. 1988;37:408-412.

Carmichael FJ, Cruise CJ, Crago RR. Preoxygenation: a study of denitrogenation. Anesth Analg. 1989;68:406-409.

Edmark L, Kostova-Aherdan K, Enlund M. Optimal oxygen concentration during induction of general anesthesia. Anesthesiology. 2003;98:28-33.

5dd6d5690e88259f7c13f286 rba Articles
Links & Downloads
2352-2291 (Electronic) 0104-0014 (Printed)
Braz J Anesthesiol ©2024 All rights reserved.

Braz J Anesthesiol

Share this page
Page Sections