- Email: [email protected]
Positive end-expiratory pressure during surgery
Correspondence
We declare no competing interests.
*Nestor E Vain, Luis M Prudent, Daniela S Satragno, Juan E Gordillo, Adriana N Gorenstein [email protected] Foundation for Maternal and Child Health (FUNDASAMIN), Honduras 4160, Buenos Aires, Argentina (NEV, LMP, DSS, AN); and Institute of Maternity Our Lady of Mercy, San Miguel de Tucumán, Argentina (JEG) 1
2
3
4
5
Vain NE, Satragno DS, Gorenstein AN, et al. Effect of gravity on volume of placental transfusion: a multicentre, randomised, non-inferiority trial. Lancet 2014; 384: 235–40. Kattwinkel J, Perlman JM, Aziz K, et al. Neonatal resuscitation: 2010 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Pediatrics 2010; 126: e1400–13. Chaparro CM, Neufeld LM, Tena Alavez G, Eguia-Líz Cedillo R, Dewey KG. Effect of timing of umbilical cord clamping on iron status in Mexican infants: a randomized controlled trial. Lancet 2006; 367: 1997–2004. Ceriani Cernadas JM, Carroli G, Pellegrini L, et al. The effect of early and delayed umbilical cord clamping on ferritin levels in term infants at six months of life: a randomized, controlled trial. Arch Argent Pediatr 2010; 108: 201–08 (in Spanish). Bewley S, Díaz-Rossello JL, Mercer J. Natural stem cell transplantation: interventions, nuances and ethics. J Cell Mol Med 2010; 14: 2840–41.
Positive end-expiratory pressure during surgery With great interest, I read the Article by PROVE Network Investigators (Aug 9, p 495)1 and the accompanying Comment. 2 Some of the study limitations that might have obscured any treatment effect (eg, protocol deviations, infrequent recruitment manoeuvres, and a high positive end-expiratory pressure [PEEP] level in the higher PEEP group) have been addressed in the accompanying Comment.2 Several additional factors might have negated any potential treatment effect. www.thelancet.com Vol 384 November 8, 2014
39% of patients in both groups had received thoracic epidural analgesia. Compared with systemic analgesia, thoracic epidural analgesia can be expected to improve the postoperative pulmonary outcome in patients undergoing abdominal surgery.3 At the same time, the combination of thoracic epidural analgesia, general anesthesia, and mechanical ventilation frequently causes hypotension, which requires therapy.4 Any possible difference in pulmonary outcome between groups might have been obscured by the beneficial pulmonary effects of thoracic epidural analgesia. Similarly, the higher incidence of intraoperative hypotension and increased need for vasoactive drugs in the high compared with the low PEEP group might not have mainly been caused by the high PEEP per se but instead by the combination of high PEEP, thoracic epidural analgesia, and general anaesthesia. To compare the primary and secondary outcome variables between patients with and without thoracic epidural analgesia would be relevant. Combined abrupt withdrawal of 12 cm H2O PEEP and restoration of spontaneous respiration at the time of extubation will have acutely increased venous return and, in turn, right and left ventricular preload. This might have increased lung water in patients with left ventricular dysfunction with unpredictable subsequent adverse pulmonary sequelae. All patients had received intermediate longacting muscle relaxants. Residual neuromuscular blockade must be expected at the end of surgery in up to 80% of cases.5 Residual neuromuscular blockade is associated with impaired postoperative lung function and postoperative pulmonary morbidity.5,6 Because the detrimental effect of residual neuromuscular blockade on postoperative pulmonary outcome might have obscured any potential treatment effects, we need to know whether neuromuscular function was quantitatively assessed before extubation.
Extubation during an inspired oxygen fraction (FiO 2) of 1·0 is associated with worse post-extubation atelectasis and oxygenation compared with extubation at a lower FiO2.7 Use of an FiO2 of 1·0 at the time of extubation in all patients might partly explain the absence of difference in postoperative atelectasis. I declare no competing interests.
Hans-Joachim Priebe [email protected] Department of Anaesthesia, University Hospital Freiburg, Freiburg im Breisgau 79106, Germany 1
2 3
4
5
6
7
The PROVE Network Investigators for the Clinical Trial Network of the European Society of Anaesthesiology. High versus low positive end-expiratory pressure during general anaesthesia for open abdominal surgery (PROVHILO trial): a multicentre randomised controlled trial. Lancet 2014; 384: 495–503. Futier E. Positive end-expiratory pressure in surgery: good or bad? Lancet 2014; 384: 472–74. Pöpping DM, Elia N, Marret E, Remy C, Tramèr MR. Protective effects of epidural analgesia on pulmonary complications after abdominal and thoracic surgery. A meta-analysis. Arch Surg 2008; 143: 990–99. De Kock M, Laterre P-F, Andruetto P, et al. Ornipressin (Por 8): an efficient alternative to counteract hypotension during combined general/epidural anesthesia. Anesth Analg 2000; 90: 1301–07. Plaud B, Debaene B, Donati F, Marty J. Residual paralysis after emergence from anesthesia. Anesthesiology 2010; 112: 1013–22. Berg H, Viby-Mogensen J, Roed J, et al. Residual neuromuscular block is a risk factor for postoperative pulmonary complications: A prospective, randomised, and blinded study of postoperative pulmonary complications after atracurium, vecuronium and pancuronium. Acta Anaesthesiol Scand 1997; 41: 1095–103. Benoît Z, Wicky S, Fischer J-F, et al. The effect of increased FiO2 before tracheal extubation on postoperative atelectasis. Anesth Analg 2002; 95: 1777–81.
We read with interest the PROVHILO study 1 comparing high with low positive end-expiratory pressure (PEEP) during general anaesthesia for open abdominal surgery. The researchers concluded that high PEEP and recruitment manoeuvres during open abdominal surgery do not protect against postoperative pulmonary complications. 1 We commend the investigators for providing such highly needed data; however, we believe that a major contributing factor that could
Jim Varney/Science Photo Library
amenable to treatment with stem cells when a sibling is born. Bewley and colleagues 5 describe our thinking quite well: “There is no proven benefit of interrupting umbilical blood flow before its natural cessation. Until then, the only ethical bank recipient is the newborn infant.”
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We declare no competing interests.
*Nestor E Vain, Luis M Prudent, Daniela S Satragno, Juan E Gordillo, Adriana N Gorenstein [email protected] Foundation for Maternal and Child Health (FUNDASAMIN), Honduras 4160, Buenos Aires, Argentina (NEV, LMP, DSS, AN); and Institute of Maternity Our Lady of Mercy, San Miguel de Tucumán, Argentina (JEG) 1
2
3
4
5
Vain NE, Satragno DS, Gorenstein AN, et al. Effect of gravity on volume of placental transfusion: a multicentre, randomised, non-inferiority trial. Lancet 2014; 384: 235–40. Kattwinkel J, Perlman JM, Aziz K, et al. Neonatal resuscitation: 2010 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Pediatrics 2010; 126: e1400–13. Chaparro CM, Neufeld LM, Tena Alavez G, Eguia-Líz Cedillo R, Dewey KG. Effect of timing of umbilical cord clamping on iron status in Mexican infants: a randomized controlled trial. Lancet 2006; 367: 1997–2004. Ceriani Cernadas JM, Carroli G, Pellegrini L, et al. The effect of early and delayed umbilical cord clamping on ferritin levels in term infants at six months of life: a randomized, controlled trial. Arch Argent Pediatr 2010; 108: 201–08 (in Spanish). Bewley S, Díaz-Rossello JL, Mercer J. Natural stem cell transplantation: interventions, nuances and ethics. J Cell Mol Med 2010; 14: 2840–41.
Positive end-expiratory pressure during surgery With great interest, I read the Article by PROVE Network Investigators (Aug 9, p 495)1 and the accompanying Comment. 2 Some of the study limitations that might have obscured any treatment effect (eg, protocol deviations, infrequent recruitment manoeuvres, and a high positive end-expiratory pressure [PEEP] level in the higher PEEP group) have been addressed in the accompanying Comment.2 Several additional factors might have negated any potential treatment effect. www.thelancet.com Vol 384 November 8, 2014
39% of patients in both groups had received thoracic epidural analgesia. Compared with systemic analgesia, thoracic epidural analgesia can be expected to improve the postoperative pulmonary outcome in patients undergoing abdominal surgery.3 At the same time, the combination of thoracic epidural analgesia, general anesthesia, and mechanical ventilation frequently causes hypotension, which requires therapy.4 Any possible difference in pulmonary outcome between groups might have been obscured by the beneficial pulmonary effects of thoracic epidural analgesia. Similarly, the higher incidence of intraoperative hypotension and increased need for vasoactive drugs in the high compared with the low PEEP group might not have mainly been caused by the high PEEP per se but instead by the combination of high PEEP, thoracic epidural analgesia, and general anaesthesia. To compare the primary and secondary outcome variables between patients with and without thoracic epidural analgesia would be relevant. Combined abrupt withdrawal of 12 cm H2O PEEP and restoration of spontaneous respiration at the time of extubation will have acutely increased venous return and, in turn, right and left ventricular preload. This might have increased lung water in patients with left ventricular dysfunction with unpredictable subsequent adverse pulmonary sequelae. All patients had received intermediate longacting muscle relaxants. Residual neuromuscular blockade must be expected at the end of surgery in up to 80% of cases.5 Residual neuromuscular blockade is associated with impaired postoperative lung function and postoperative pulmonary morbidity.5,6 Because the detrimental effect of residual neuromuscular blockade on postoperative pulmonary outcome might have obscured any potential treatment effects, we need to know whether neuromuscular function was quantitatively assessed before extubation.
Extubation during an inspired oxygen fraction (FiO 2) of 1·0 is associated with worse post-extubation atelectasis and oxygenation compared with extubation at a lower FiO2.7 Use of an FiO2 of 1·0 at the time of extubation in all patients might partly explain the absence of difference in postoperative atelectasis. I declare no competing interests.
Hans-Joachim Priebe [email protected] Department of Anaesthesia, University Hospital Freiburg, Freiburg im Breisgau 79106, Germany 1
2 3
4
5
6
7
The PROVE Network Investigators for the Clinical Trial Network of the European Society of Anaesthesiology. High versus low positive end-expiratory pressure during general anaesthesia for open abdominal surgery (PROVHILO trial): a multicentre randomised controlled trial. Lancet 2014; 384: 495–503. Futier E. Positive end-expiratory pressure in surgery: good or bad? Lancet 2014; 384: 472–74. Pöpping DM, Elia N, Marret E, Remy C, Tramèr MR. Protective effects of epidural analgesia on pulmonary complications after abdominal and thoracic surgery. A meta-analysis. Arch Surg 2008; 143: 990–99. De Kock M, Laterre P-F, Andruetto P, et al. Ornipressin (Por 8): an efficient alternative to counteract hypotension during combined general/epidural anesthesia. Anesth Analg 2000; 90: 1301–07. Plaud B, Debaene B, Donati F, Marty J. Residual paralysis after emergence from anesthesia. Anesthesiology 2010; 112: 1013–22. Berg H, Viby-Mogensen J, Roed J, et al. Residual neuromuscular block is a risk factor for postoperative pulmonary complications: A prospective, randomised, and blinded study of postoperative pulmonary complications after atracurium, vecuronium and pancuronium. Acta Anaesthesiol Scand 1997; 41: 1095–103. Benoît Z, Wicky S, Fischer J-F, et al. The effect of increased FiO2 before tracheal extubation on postoperative atelectasis. Anesth Analg 2002; 95: 1777–81.
We read with interest the PROVHILO study 1 comparing high with low positive end-expiratory pressure (PEEP) during general anaesthesia for open abdominal surgery. The researchers concluded that high PEEP and recruitment manoeuvres during open abdominal surgery do not protect against postoperative pulmonary complications. 1 We commend the investigators for providing such highly needed data; however, we believe that a major contributing factor that could
Jim Varney/Science Photo Library
amenable to treatment with stem cells when a sibling is born. Bewley and colleagues 5 describe our thinking quite well: “There is no proven benefit of interrupting umbilical blood flow before its natural cessation. Until then, the only ethical bank recipient is the newborn infant.”
1669