LETTER TO THE EDITOR
Aveolar recruitment maneuver in anesthetic practice: How, when and why it may be useful
Mrs. Editor,
It was with great interest that I read the above-mentioned article published by our respectful journal. I would like to congratulate the authors for the appreciable initiative. Concerned with explaining some aspects, I thought about making some observations:
I wish to congratulate the authors for their elegant study which has called our attention for the possibility of optimizing our anesthetic technique to benefit patients.
Yours truly
Fabiano Timbó Barbosa, TSA, M.D.
REFERENCES
01. Hedenstierna G Atelectasis and gas exchange during anaesthesia. Electromedica, 2003;71:70-73.
02. Smith RA, Bratzke EC, Miguel RV Constant positive airway pressure reduces hypoventilation induced by inhalation anesthesia. J Clin Anesth, 2005;17:44-50.
03. Rusca M, Proietti S, Schnyder P et al Prevention of atelectasis formation during induction of general anesthesia. Anesth Analg, 2003;97:1835-1839.
04. Yoshino J, Akata T, Takahashi S Intraoperative changes in arterial oxygenation during volume-controlled mechanical ventilation in modestly obese patients undergoing laparotomies with general anesthesia. Acta Anaesthesiol Scand, 2003;47: 742-750.
05. Wetterslev J, Hansen EG, Roikjaer O et al Optimizing preoperative compliance with PEEP during upper abdominal surgery: effects on perioperative oxygenation and complications in patients without preoperative cardiopulmonary dysfunction. Eur J Anaesth, 2001;18:358-365.
06. Coussa M, Proietti S, Schnyder P et al Prevention of atelectasis formation during the induction of general anesthesia in morbidly obese patients. Anesth Analg, 2004;98:1491-1495.
Reply
Mrs. Editor,
I was happy to receive Dr. Fabiano's flattering letter. I thank for the praises and would like to add some comments:
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In fact, high tidal volumes promote cyclic alveolar hyperdistension and collapse as mentioned in our study. He is right when stating that there are no evidences of problems in anesthetized patients with high volumes, provided patients have no pulmonary disease; however it is known that such high volumes when used for a long time may promote volutrauma and should be avoided in any situation.
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In fact, CPAP can only be used in patients under spontaneous ventilation, so it could only be used in anesthetized patients being weaned from ventilatory prosthesis and close to extubation. It is possible that, in patients free from pulmonary disease, pressure levels for recruitment are lower than 30 to 40 cmH
2O, as mentioned by Dr. Fabiano in the study by Smith et al. These pressure levels of 30 to 40 cmH
2O mentioned by us were used in patients with ARDS, that is, patients with decreased pulmonary compliance
1,2.
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We advocate PaO
2 or PaO
2/FiO
2 ratio evaluation to check alveolar recruitment efficacy because it is simpler and of lower cost as compared to the other method described in the literature, which is chest tomography. Yoshino et al.'s conclusion, after observing that obese and overweighed patients ventilated without recruitment maneuver or PEEP evolved with decreased PaO
2/FiO
2 ratio, is in line with the literature. When there are facts changing ventilatory mechanics or in the presence of pulmonary diseases, there is higher possibility of atelectasis and higher is the importance of adequate ventilation.
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Dr. Fabiano is right with regard to the fact that "further studies are needed to define the optimal ARM time and its real role in the more favorable evolution of patients" and is in line with our conclusions that routine recruitment maneuver in anesthesia cannot be recommended because it is not based on studies with high levels of evidence.
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PEEP and low FiO
2 are undoubtedly effective methods to prevent alveolar collapse.
With this literature review we tried to bring to anesthesiologists intensive care practices which may help solving some anesthetic complications.
We greatly thank Dr. Fabiano for the opportunity to further discuss this subject.
Domingos Dias Cicarelli, TSA, M.D.
REFERENCES
01. Carvalho CRR Ventilação Mecânica I. Clínicas Brasileiras de Medicina Intensiva, 1ª Ed, São Paulo, Atheneu, 2000.
02. Carvalho CRR Ventilação Mecânica II. Clínicas Brasileiras de Medicina Intensiva, 1ª Ed, São Paulo, Atheneu, 2000.
01. Carvalho CRR Ventilação Mecânica I. Clínicas Brasileiras de Medicina Intensiva, 1ª Ed, São Paulo, Atheneu, 2000.
Publication Dates
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Publication in this collection
29 May 2006 -
Date of issue
June 2006