ORIGINAL ARTICLE
The Effects of Different Oxygen Concentrations on Recruitment Maneuver During General Anesthesia for Laparoscopic Surgery Ufuk Topuz, MD,* Ziya Salihoglu, MD,* Banu V. Gokay, MD,w Tarik Umutoglu, MD,* Mefkur Bakan, MD,* and Kadir Idin, MD*
Introduction and Purpose: Recruitment maneuvers (RMs), which aim to ventilate the collaborated alveolus by temporarily increasing the transpulmonary pressure, have positive effects in relation to respiration, mainly oxygenation. Although many studies have defined the pressure values used during RM and the application period, our knowledge of the effects of different oxygen concentrations is limited. In this study, we aimed to determine the effects of different oxygen concentrations during RM on the arterial oxygenation and respiration mechanics in laparoscopic cases. Materials and Methods: Thirty-two patients undergoing laparoscopic cholecystectomy were recruited into the study. The patients were randomly divided into 2 groups. RM with a 30% oxygen concentration was performed in patients within the first group (group I, n = 16), whereas patients in the second group (group II, n = 16) received RM with 100% oxygen. To study respiratory mechanics, dynamic compliance (Cdyn), airway resistance (Raw), and peak inspiratory pressure were measured at 3 different times: 5 minutes after anesthesia induction, 5 minutes after the abdomen was insufflated, and 5 minutes after the abdomen was desufflated. Arterial blood gases were measured during surgery and 30 minutes after surgery (postoperative). Results: The average postoperative partial arterial oxygen pressure values of the patients in groups I and II were 121 and 98 mm Hg, respectively. The difference between the groups was statistically significant. In addition, the decrease in compliance from induction values after desufflation in group II was statistically significant. Discussion: On the basis of our results, maintaining oxygen concentrations below 100% during RM may be more beneficial in terms of respiratory mechanics and gas exchange. Key Words: general anesthesia, laparoscopic surgery, pneumoperitoneum, respiratory mechanics, arterial blood gases, recruitment maneuver
(Surg Laparosc Endosc Percutan Tech 2014;24:410–413)
A
telectasis occurs after anesthesia induction, even in healthy patients. Intraoperative shunts increase during operation, which can disrupt gas exchange.1,2 In laparoscopic surgery, respiratory functions are more obviously Received for publication September 25, 2013; accepted January 4, 2014. From the *Department of Anesthesiology and Reanimation, Faculty of Medicine, Bezmialem Vakif University; and wDepartment of Anesthesiology and Reanimation, Faculty of Medicine, Kemerburgaz University, Istanbul, Turkey. The authors declare no conflicts of interest. Reprints: Ufuk Topuz, MD, Department of Anesthesiology and Reanimation, Faculty of Medicine, Bezmialem Vakif University, Vatan cad, Fatih, Istanbul 34093, Turkey (e-mail: ufuktopuz@hotmail. com). Copyright r 2014 by Lippincott Williams & Wilkins
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affected. Microairways are closed secondary to cephalad displacement of the diaphragm because of pneumoperitonium. Atelectasis occurs in dependent lung parts, and the functional residual capacity decreases.3–6 Recruitment maneuvers (RMs) to open collapsed alveoli and for the correction of gas exchange have been defined and are commonly applied today.7,8 The positive effects of RM on respiratory mechanics and oxygenation during and after operation have been demonstrated.7,8 In terms of respiratory mechanics and oxygenation, a number of recent studies have shown the usefulness of RM, which are applied during pneumoperitonium and laparoscopic surgery.9–13 The duration of the maneuvers and the applied pressure values have been defined in detail in previous studies. Despite these detailed definitions, the effects of oxygen and oxygen percentage used during the process have not been an area of focus. Some studies have also suggested that high oxygen concentrations during preoxygenation during anesthesia induction increases atelectasis.14,15 These studies showed that atelectasis after preoxygenation with an oxygen concentration of 100% were more profound than that with preoxygenation using lower oxygen concentrations.14,15 Although the effects of oxygen concentration changes are known, there are not enough studies comparing different oxygen concentrations during RM. We planned this study with the hypothesis that oxygen concentrations below 100% would improve the results of RM. The purpose of this study was to compare the effects of different oxygen concentrations applied during RM, on respiratory mechanics and arterial blood gases.
MATERIALS AND METHODS The study was initiated after obtaining the approval of the ethics committee. Thirty-two patients undergoing laparoscopic cholecystectomy at our hospital were recruited into the study. Written informed consent was obtained from each patient. Only patients who were classified as I-II based on the American Society of Anesthesiologists (ASA) were included in the study. Patients with respiratory system and/or cardiovascular system diseases; those using drugs that may affect the respiratory function, smokers, obese patients; and patients older than 65 years were not included in the study. Patients were randomly assigned to 1 of the 2 groups. Patients in the first group (group I, n = 16) received 30% oxygen, and patients in the second group (group II, n = 16) received 100% oxygen during RM. Vascular access was established from the dorsum of the hand or antecubital area with a 20-G cannula, followed by the infusion of 0.9% NaCl and premedication was provided by IV midazolam 0.03 mg/kg (Demizolam; Dem
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I˙lac¸, Istanbul, Turkey) in a preoperative preparation room. The electrocardiography, peripheral oxygen saturation (SpO2), and noninvasive blood pressure values of the patients who were taken to the operating table were monitored using a Millenia device (Orlando). For anesthesia induction, propofol 2 mg/kg (propofol %1; Fresenius Kabi, Uppsala, Sweden), morphine 0.1 mg/kg, and cisatracurium 0.15 mg/kg (Nimbex; GlaxoSmithKline, UK) were used. A nasogastric catheter was placed after intubation. For anesthesia maintenance, sevoflurane (Sevorane; Abbott, UK) 1% to 2% in oxygen-air mixture and remifentanil (Ultiva; GlaxoSmithKline) infusion 0.1 to 0.5 mg/ kg/min were used. Neuromuscular monitoring was not used and cisatracurium 0.05 mg/kg was repeated 40 minutes after induction with 20-minute intervals. During the operation, mechanical ventilation was applied using a Dra¨ger Sulla 808 V (Lu¨beck, Germany) device, with a FiO2 value of 0.5, a tidal volume of 8 to 10 mL/kg, and a respiratory rate of 12 to 14 breaths/min. The ventilation parameters were adjusted to obtain an end-tidal carbon dioxide (EtCO2) value between 30 and 35 mm Hg. Each patient was administered an Allen test, and a cannula was placed in the radial artery after anesthesia induction. Intraperitoneal carbon dioxide (CO2) was insufflated with a 2 L/min flow rate to create a surgical field by a laparoscopic insufflation apparatus (Storz, Tuttlingen, Germany). During the operative period, the intra-abdominal pressure was maintained below 12 mm Hg. RM was applied during the operation when the clamp was placed in the cystic duct. The patients were administered RM 2 times for 30 seconds with 1-minute interval and a 30 mm Hg peak pressure using oxygen concentrations for group assignments as defined above. Dynamic compliance (Cdyn), airway resistance (Raw), and peak inspiratory pressure (PIP) were measured 3 times during the operation: 5 minutes after anesthesia induction (induction), 5 minutes after the abdomen was insufflated (insufflation), and 5 minutes after the abdomen was desufflated (desufflation). The measurements were made using a respiratory mechanics monitor (Ventrak, Respiratory Mechanics Monitoring System, Novametrix Medical Systems Wallingford, CT). The postoperative arterial blood gas of the patients was measured simultaneously and 30 minutes after the operation (postoperative). The blood gas levels were analyzed using the Ciba Corning 860 apparatus (Massachusetts). The sample size requirement was based on a previous study conducted at our institution.16 Thus, at an a error of 0.05, 16 patients per each group would provide 80% power and detect a difference of 5 mm Hg for partial arterial carbon dioxide pressure (PaCO2) levels with a SD of 4.9. For statistical analysis of the collected data, analysis of variance-repeated measures analysis, with post hoc TukeyKramer multiple comparisons test, unpaired Student t test, and w2 test were used where appropriate. Values of P < 0.05 were accepted as statistically significant.
RESULTS The characteristics of the patients in the 2 groups were statistically similar in terms of age, weight, sex, ASA score, and duration of the operation (Table 1). On the basis of blood gas analysis (Table 2), compared with the induction period, the changes in the pH and PaCO2 values during the desufflation period were r
2014 Lippincott Williams & Wilkins
Recruitment Maneuver for Pneumoperitoneum
TABLE 1. Patient and Operation Characteristics
Group I (n = 16)
Group II (n = 16)
14/2 45 ± 11 65 ± 18 8/8 44 ± 11
12/4 48 ± 13 69 ± 16 7/9 49 ± 21
Female/male Age (y) Weight (kg) ASA status I/II Duration of operation (min)
Data are shown as number of patients or mean ± SD. ASA indicates American Society of Anesthesiologists.
statistically significant for both groups (P < 0.05). However, the PaO2 level varied between measures versus the initial measure and was found to be statistically significant. For the intergroup comparison, the PaO2 value was determined as statistically significantly lower in the postoperative period in group II when compared with group I (P < 0.05). No statistically significant difference was determined in the bicarbonate values of the 2 groups. The respiratory mechanics also showed similar variations in both the groups (Table 3). At the insufflation period in both groups, Cdyn values decreased, whereas Raw and PIP values increased compared with the induction period and those changes were statistically significant (P < 0.05). Furthermore, a statistically significant correction was observed in Cdyn, Raw, and PIP values at the desufflation period when compared with the insufflation period. After desufflation, Cdyn values increased compared with insufflation period in both the groups, which were statistically
TABLE 2. Arterial Blood Gas Analyses
Group I (n = 16) pH Induction Insufflation Desufflation Postoperative PaCO2 (mm Hg) Induction Insufflation Desufflation Postoperative PaO2 (mm Hg) Induction Insufflation Desufflation Postoperative HCO3 Induction Insufflation Desufflation Postoperative
Group II (n = 16)
7.40 ± 0.07 7.39 ± 0.08 7.35 ± 0.05* 7.37 ± 0.04
7.39 ± 0.05 7.37 ± 0.04 7.35 ± 0.03* 7.37 ± 0.07
36 ± 5 39 ± 9 41 ± 7* 39 ± 8
36 ± 9 38 ± 5 40 ± 6* 39 ± 5
148 ± 25 131 ± 21* 136 ± 25* R 121 ± 24*w 24 ± 8 25 ± 7 24 ± 9 23 ± 6
153 ± 25 135 ± 15* 138 ± 26* R 98 ± 18*w # 23 ± 7 22 ± 8 21 ± 6 22 ± 5
Data are shown as mean ± SD. Desufflation indicates 5 minutes after the abdomen was desufflated; induction, 5 minutes after anesthesia induction; insufflation, 5 minutes after the abdomen was insufflated; PaCO2, partial arterial carbon dioxide pressure; PaO2, partial arterial oxygen pressure; postoperative, 30 minutes after the operation. *P < 0.05 compared with induction period. RwP < 0.05 compared with insufflation period. P < 0.05 compared with desufflation period. #P < 0.05 between groups.
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Topuz et al
TABLE 3. Respiratory Mechanics Cdyn (mL/cm H2O) Induction Insufflation Desufflation Raw (cm H2O/L/sec) Induction Insufflation Desufflation PIP (mm Hg) Induction Insufflation Desufflation
Group I (n = 16)
Group II (n = 16)
43 ± 13 34 ± 11* 42 ± 7w
42 ± 11 32 ± 8* 37 ± 11w#
16 ± 7 23 ± 7* 18 ± 8w
17 ± 5 22 ± 7* 17 ± 7w
18 ± 5 22 ± 8* 19 ± 7w
16 ± 6 23 ± 7* 17 ± 8w
Data are shown as mean ± SD. Cdyn indicates dynamic compliance; desufflation, 5 minutes after the abdomen was desufflated; induction, 5 minutes after anesthesia induction; insufflation, 5 minutes after the abdomen was insufflated; PIP, peak inspiratory pressure; Raw, resistance of airway. *P < 0.05 compared with induction period. wP < 0.05 compared with insufflation period. #P < 0.05 between groups.
significant. In group I, Cdyn values at the desufflation period were statistically significantly higher compared with those in group II.
DISCUSSION An alveolar recruitment method is useful for increasing arterial oxygenation and improving respiratory mechanics.9,14,15 This study examines the effects of the different oxygen concentrations used in RM during pneumoperitonium on respiratory mechanics and blood gas values. As estimated, we reached higher arterial blood gas oxygen pressures in the postoperative period in patients who were administered 30% oxygen during RM compared with the group that was given 100% oxygen during RM. After desufflation compliance also remained significantly higher in the 30% oxygen group. We propose that this is related to the atelectasis development owing to the high oxygen concentration. There are several RMs that have been defined. Generally, researchers report the pressure values and times that were used during the RM in detail but do not provide any information on the gas mixture used during recruitment. The most frequently used parameters are 15 seconds of positive pressure applied at 40 cm H2O.7 This is the pressure required for the generation of vital capacity and is termed the vital capacity maneuver. Rothen et al17 stated that a 7second application of pressure was adequate for the effectiveness of vital capacity maneuver. In another study, recruitment was made by selecting a 2-minute pressurecontrolled ventilation mode while using positive endexpiratory pressure (PEEP) at 20 cm H2O, such that the respiratory frequency was 12 breaths/min and the peak pressure was 40 cm H2O.18 The inspiratory time was set as 4 seconds and the expiratory time was set as 1 second (inspiration time:expiration time = 4:1). In addition, there are many studies that address the use of PEEP postmaneuver during anesthesia or in patients with acute lung injury to prevent the regeneration of atelectasia.7,19–21 The oxygen percentage was either not specified or kept at 100% in most of these studies, and the potential effects of high oxygen concentration were not assessed. However, high
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oxygen concentrations used during operation may have harmful effects. Absorption atelectasis may occur as oxygen, which replaces the less soluble nitrogen and leaves the alveoli in patients respiring oxygen for a long time at 80% to 100% concentrations. The inadequacy of the secretion excretion, replacement of nitrogen by volatile anesthetics, and the high oxygen concentration that is used during general anesthesia can lead to the development of resorption atelectasis after general anesthesia.22 Rothen and colleagues investigated the effects of the gas composition used during general anesthesia induction on the generation of atelectasis and gas exchange. The authors used 30% oxygen in one group and 100% oxygen in the other group during induction, and they concluded that the use of low oxygen concentrations prevents the generation of atelectasis in the early period.20 Edmark et al23 investigated optimum oxygen concentration values that would discourage the generation of atelectasis, keeping in consideration that the use of low oxygen concentrations during preoxygenation may increase the risk of hypoxemia during apnea. Oxygen concentrations of 80% and 60% were used during preoxygenation, and no increase was observed in the percentage of atelectasis in either of the groups. The apnea time when oxygen saturation was decreased to 90% was found to be >5 minutes in the 80% oxygen concentration group.23 Rothen et al24 published a study similar to ours in 1995. By using 40% and 100% oxygen concentrations in the RM in 12 brain surgery and general surgery cases, respectively, the authors assessed these patients in terms of atelectasis by computer tomography, blood gas assessments, and compliance measurements. The authors found that atelectasis developed in all patients after anesthesia induction, and this atelectasis was abolished with the RM in all patients. Furthermore, the authors determined that the amount of atelectasis was increased to a value closed to prerecruitment value 5 minutes after the RM with 100% oxygen, whereas there was a small increase in the amount of atelectasis, which reached about one sixth of the initial area of atelectasis 40 minutes after the RM with 40% oxygen. However, compliance changes showed no difference between groups and they found no correlation between compliance and atelectasis. The authors attributed this to the existence of factors other than atelectasis that could affect compliance. In our study, when compared with insufflation period, compliance increased in both groups in the desufflation period, which corresponds to the post-RM period; however, it did not reach the original value at the induction period in the group that was administered 100% oxygen. When compared with the aforementioned study, our patient group had higher risk for atelectasis because of laparoscopy. The fact that our study included only healthy patients with normal respiratory function may be considered a weakness. Studies that include patients, who are also susceptible to atelectasis (such as obesity) or patients with respiratory disease and who also have low PaO2 levels, may be of greater value. We conclude that oxygen concentration is as important as the pressure values and times used during RM when applied to prevent atelectasis. On the basis of our results, during RM it is reasonable to keep oxygen concentration at a level low enough to maintain SpO2 > 90%. The unfavorable results of redundant high oxygen concentrations during RM may not be clinically significant in healthy individuals, but patients who are vulnerable to low PaO2 levels may be impacted. Further studies are required to assess the optimum oxygen concentrations for RM that r
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should be used to prevent hypoxia in both healthy individuals and patients with comorbidities. Use of CT scan to determine the quantity and location of possible atelectasis and additional ventilation/perfusion studies and respiratory function analysis could be useful to evaluate the effects of RM with different oxygen concentrations. REFERENCES 1. Marshall BE, Wyche MQ Jr. Hypoxemia during and after anesthesia. Anesthesiology. 1972;37:178–209. 2. Hedenstierna G. Gas exchange during anesthesia. Br J Anaesth. 1990;64:507–514. 3. Andersson LE, Ba˚a˚th M, Tho¨rne A, et al. Effect of carbon dioxide pneumoperitoneum on development of atelectasis during anesthesia, examined by spiral computed tomography. Anesthesiology. 2005;102:293–299. 4. El-Dawlatly AA, Al-Dohayan A, Abdel-Meguid ME, et al. The effects of pneumoperitoneum on respiratory mechanics during general anesthesia for bariatric surgery. Obes Surg. 2004;14:212–225. 5. Nguyen NT, Wolfe BM. The physiologic effects of pneumoperitoneum in the morbidly obese. Ann Surg. 2005;241:219–226. 6. Salihoglu Z, Demiroluk S, Baca B, et al. Effects of pneumoperitoneum and positioning on respiratory mechanics in chronic obstructive pulmonary disease patients during Nissen fundoplication. Surg Laparosc Endosc Percutan Tech. 2008;18:437–440. 7. Rothen HU, Sporre B, Englberg G, et al. Re-expansion of atelectasis during general anesthesia: a computed tomography study. Br J Anaesth. 1993;71:788–795. 8. Tusman G, Bo¨hm SH, Vazquez de Anda GF, et al. “Alveolar recruitment strategy” improves arterial oxygenation during general anesthesia. Br J Anaesth. 1999;82:8–13. 9. Whalen FX, Gajic O, Thompson GB, et al. The effects of the alveolar recruitment maneuver and positive end-expiratory pressure on arterial oxygenation during laparoscopic bariatric surgery. Anesth Analg. 2006;102:298–305. 10. Cinnella G, Grasso S, Spadaro S, et al. Effects of recruitment maneuver and positive end-expiratory pressure on respiratory mechanics and transpulmonary pressure during laparoscopic surgery. Anesthesiology. 2013;118:114–122. 11. Talab HF, Zabani IA, Abdelrahman HS, et al. Intraoperative ventilatory strategies for prevention of pulmonary atelectasis in
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12.
13. 14. 15.
16. 17. 18.
19. 20. 21. 22. 23. 24.
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obese patients undergoing laparoscopic bariatric surgery. Anesth Analg. 2009;109:1511–1516. Futier E, Constantin JM, Pelosi P, et al. Intraoperative recruitment maneuver reverses detrimental pneumoperitoneuminduced respiratory effects in healthy weight and obese patients undergoing laparoscopy. Anesthesiology. 2010;113:1310–1319. Salihoglu Z, Baca B, Koksal S, et al. Analysis of laparoscopic colorectal surgery in high-risk patients. Surg Laparosc Endosc Percutan Tech. 2009;19:397–400. Pang CK, Yap J, Chen PP. The effect of an alveolar recruitment strategy on oxygenation during laparoscopic cholecystectomy. Anaesth Intensive Care. 2003;31:176–180. Valenza F, Vagginelli F, Tiby A, et al. Effects of the beach chair position, positive end-expiratory pressure, and pneumoperitoneum on respiratory function in morbidly obese patients during anesthesia and paralysis. Anesthesiology. 2007;107: 725–732. Salihoglu Z, Demiroluk S, Cakmakkaya S, et al. Influence of patient positioning on respiratory mechanics during pneumoperitoneum. Middle East J Anesthesiol. 2002;16:521–528. Rothen HU, Neumann P, Berglund JE, et al. Dynamics of reexpansion of atelectasis during general anesthesia. Br J Anaesth. 1999;82:551–556. Claesson J, Lehtipalo S, Johansson G, et al. Evaluation of intestinal preconditioning in a porcine model using classic ischemic preconditioning or lung recruitment maneuvers. Shock. 2008;29:98–103. Rothen HU, Sporre B, Englberg G, et al. Reexpansion of atelectasis during general anesthesia may have a prolonged effect. Acta Anaesthesiol Scand. 1995;39:118–125. Rothen HU, Sporre B, Englberg G, et al. Prevention of atelectasis during general anesthesia. Lancet. 1995;345:1387–1391. Rothen HU, Sporre B, Englberg G, et al. Atelectasis and pulmonary shunting during induction of general anesthesia: can they be avoided? Acta Anaesthesiol Scand. 1996;40:524–529. Salihoglu Z. Oxygen concentration during recruitment manoeuvre. Aust J Physiother. 2008;54:150. Edmark L, Kostova-Aherdan K, Enlund M, et al. Optimal oxygen concentration during induction of general anesthesia. Anesthesiology. 2003;98:28–33. Rothen HU, Sporre B, Engberg G, et al. Influence of gas composition on recurrence of atelectasis after a reexpansion maneuver during general anesthesia. Anesthesiology. 1995; 82:832–842.
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The Effects of Different Oxygen Concentrations on Recruitment Maneuver During General Anesthesia for Laparoscopic Surgery Ufuk Topuz, MD,* Ziya Salihoglu, MD,* Banu V. Gokay, MD,w Tarik Umutoglu, MD,* Mefkur Bakan, MD,* and Kadir Idin, MD*
Introduction and Purpose: Recruitment maneuvers (RMs), which aim to ventilate the collaborated alveolus by temporarily increasing the transpulmonary pressure, have positive effects in relation to respiration, mainly oxygenation. Although many studies have defined the pressure values used during RM and the application period, our knowledge of the effects of different oxygen concentrations is limited. In this study, we aimed to determine the effects of different oxygen concentrations during RM on the arterial oxygenation and respiration mechanics in laparoscopic cases. Materials and Methods: Thirty-two patients undergoing laparoscopic cholecystectomy were recruited into the study. The patients were randomly divided into 2 groups. RM with a 30% oxygen concentration was performed in patients within the first group (group I, n = 16), whereas patients in the second group (group II, n = 16) received RM with 100% oxygen. To study respiratory mechanics, dynamic compliance (Cdyn), airway resistance (Raw), and peak inspiratory pressure were measured at 3 different times: 5 minutes after anesthesia induction, 5 minutes after the abdomen was insufflated, and 5 minutes after the abdomen was desufflated. Arterial blood gases were measured during surgery and 30 minutes after surgery (postoperative). Results: The average postoperative partial arterial oxygen pressure values of the patients in groups I and II were 121 and 98 mm Hg, respectively. The difference between the groups was statistically significant. In addition, the decrease in compliance from induction values after desufflation in group II was statistically significant. Discussion: On the basis of our results, maintaining oxygen concentrations below 100% during RM may be more beneficial in terms of respiratory mechanics and gas exchange. Key Words: general anesthesia, laparoscopic surgery, pneumoperitoneum, respiratory mechanics, arterial blood gases, recruitment maneuver
(Surg Laparosc Endosc Percutan Tech 2014;24:410–413)
A
telectasis occurs after anesthesia induction, even in healthy patients. Intraoperative shunts increase during operation, which can disrupt gas exchange.1,2 In laparoscopic surgery, respiratory functions are more obviously Received for publication September 25, 2013; accepted January 4, 2014. From the *Department of Anesthesiology and Reanimation, Faculty of Medicine, Bezmialem Vakif University; and wDepartment of Anesthesiology and Reanimation, Faculty of Medicine, Kemerburgaz University, Istanbul, Turkey. The authors declare no conflicts of interest. Reprints: Ufuk Topuz, MD, Department of Anesthesiology and Reanimation, Faculty of Medicine, Bezmialem Vakif University, Vatan cad, Fatih, Istanbul 34093, Turkey (e-mail: ufuktopuz@hotmail. com). Copyright r 2014 by Lippincott Williams & Wilkins
410 | www.surgical-laparoscopy.com
affected. Microairways are closed secondary to cephalad displacement of the diaphragm because of pneumoperitonium. Atelectasis occurs in dependent lung parts, and the functional residual capacity decreases.3–6 Recruitment maneuvers (RMs) to open collapsed alveoli and for the correction of gas exchange have been defined and are commonly applied today.7,8 The positive effects of RM on respiratory mechanics and oxygenation during and after operation have been demonstrated.7,8 In terms of respiratory mechanics and oxygenation, a number of recent studies have shown the usefulness of RM, which are applied during pneumoperitonium and laparoscopic surgery.9–13 The duration of the maneuvers and the applied pressure values have been defined in detail in previous studies. Despite these detailed definitions, the effects of oxygen and oxygen percentage used during the process have not been an area of focus. Some studies have also suggested that high oxygen concentrations during preoxygenation during anesthesia induction increases atelectasis.14,15 These studies showed that atelectasis after preoxygenation with an oxygen concentration of 100% were more profound than that with preoxygenation using lower oxygen concentrations.14,15 Although the effects of oxygen concentration changes are known, there are not enough studies comparing different oxygen concentrations during RM. We planned this study with the hypothesis that oxygen concentrations below 100% would improve the results of RM. The purpose of this study was to compare the effects of different oxygen concentrations applied during RM, on respiratory mechanics and arterial blood gases.
MATERIALS AND METHODS The study was initiated after obtaining the approval of the ethics committee. Thirty-two patients undergoing laparoscopic cholecystectomy at our hospital were recruited into the study. Written informed consent was obtained from each patient. Only patients who were classified as I-II based on the American Society of Anesthesiologists (ASA) were included in the study. Patients with respiratory system and/or cardiovascular system diseases; those using drugs that may affect the respiratory function, smokers, obese patients; and patients older than 65 years were not included in the study. Patients were randomly assigned to 1 of the 2 groups. Patients in the first group (group I, n = 16) received 30% oxygen, and patients in the second group (group II, n = 16) received 100% oxygen during RM. Vascular access was established from the dorsum of the hand or antecubital area with a 20-G cannula, followed by the infusion of 0.9% NaCl and premedication was provided by IV midazolam 0.03 mg/kg (Demizolam; Dem
Surg Laparosc Endosc Percutan Tech
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Volume 24, Number 5, October 2014
I˙lac¸, Istanbul, Turkey) in a preoperative preparation room. The electrocardiography, peripheral oxygen saturation (SpO2), and noninvasive blood pressure values of the patients who were taken to the operating table were monitored using a Millenia device (Orlando). For anesthesia induction, propofol 2 mg/kg (propofol %1; Fresenius Kabi, Uppsala, Sweden), morphine 0.1 mg/kg, and cisatracurium 0.15 mg/kg (Nimbex; GlaxoSmithKline, UK) were used. A nasogastric catheter was placed after intubation. For anesthesia maintenance, sevoflurane (Sevorane; Abbott, UK) 1% to 2% in oxygen-air mixture and remifentanil (Ultiva; GlaxoSmithKline) infusion 0.1 to 0.5 mg/ kg/min were used. Neuromuscular monitoring was not used and cisatracurium 0.05 mg/kg was repeated 40 minutes after induction with 20-minute intervals. During the operation, mechanical ventilation was applied using a Dra¨ger Sulla 808 V (Lu¨beck, Germany) device, with a FiO2 value of 0.5, a tidal volume of 8 to 10 mL/kg, and a respiratory rate of 12 to 14 breaths/min. The ventilation parameters were adjusted to obtain an end-tidal carbon dioxide (EtCO2) value between 30 and 35 mm Hg. Each patient was administered an Allen test, and a cannula was placed in the radial artery after anesthesia induction. Intraperitoneal carbon dioxide (CO2) was insufflated with a 2 L/min flow rate to create a surgical field by a laparoscopic insufflation apparatus (Storz, Tuttlingen, Germany). During the operative period, the intra-abdominal pressure was maintained below 12 mm Hg. RM was applied during the operation when the clamp was placed in the cystic duct. The patients were administered RM 2 times for 30 seconds with 1-minute interval and a 30 mm Hg peak pressure using oxygen concentrations for group assignments as defined above. Dynamic compliance (Cdyn), airway resistance (Raw), and peak inspiratory pressure (PIP) were measured 3 times during the operation: 5 minutes after anesthesia induction (induction), 5 minutes after the abdomen was insufflated (insufflation), and 5 minutes after the abdomen was desufflated (desufflation). The measurements were made using a respiratory mechanics monitor (Ventrak, Respiratory Mechanics Monitoring System, Novametrix Medical Systems Wallingford, CT). The postoperative arterial blood gas of the patients was measured simultaneously and 30 minutes after the operation (postoperative). The blood gas levels were analyzed using the Ciba Corning 860 apparatus (Massachusetts). The sample size requirement was based on a previous study conducted at our institution.16 Thus, at an a error of 0.05, 16 patients per each group would provide 80% power and detect a difference of 5 mm Hg for partial arterial carbon dioxide pressure (PaCO2) levels with a SD of 4.9. For statistical analysis of the collected data, analysis of variance-repeated measures analysis, with post hoc TukeyKramer multiple comparisons test, unpaired Student t test, and w2 test were used where appropriate. Values of P < 0.05 were accepted as statistically significant.
RESULTS The characteristics of the patients in the 2 groups were statistically similar in terms of age, weight, sex, ASA score, and duration of the operation (Table 1). On the basis of blood gas analysis (Table 2), compared with the induction period, the changes in the pH and PaCO2 values during the desufflation period were r
2014 Lippincott Williams & Wilkins
Recruitment Maneuver for Pneumoperitoneum
TABLE 1. Patient and Operation Characteristics
Group I (n = 16)
Group II (n = 16)
14/2 45 ± 11 65 ± 18 8/8 44 ± 11
12/4 48 ± 13 69 ± 16 7/9 49 ± 21
Female/male Age (y) Weight (kg) ASA status I/II Duration of operation (min)
Data are shown as number of patients or mean ± SD. ASA indicates American Society of Anesthesiologists.
statistically significant for both groups (P < 0.05). However, the PaO2 level varied between measures versus the initial measure and was found to be statistically significant. For the intergroup comparison, the PaO2 value was determined as statistically significantly lower in the postoperative period in group II when compared with group I (P < 0.05). No statistically significant difference was determined in the bicarbonate values of the 2 groups. The respiratory mechanics also showed similar variations in both the groups (Table 3). At the insufflation period in both groups, Cdyn values decreased, whereas Raw and PIP values increased compared with the induction period and those changes were statistically significant (P < 0.05). Furthermore, a statistically significant correction was observed in Cdyn, Raw, and PIP values at the desufflation period when compared with the insufflation period. After desufflation, Cdyn values increased compared with insufflation period in both the groups, which were statistically
TABLE 2. Arterial Blood Gas Analyses
Group I (n = 16) pH Induction Insufflation Desufflation Postoperative PaCO2 (mm Hg) Induction Insufflation Desufflation Postoperative PaO2 (mm Hg) Induction Insufflation Desufflation Postoperative HCO3 Induction Insufflation Desufflation Postoperative
Group II (n = 16)
7.40 ± 0.07 7.39 ± 0.08 7.35 ± 0.05* 7.37 ± 0.04
7.39 ± 0.05 7.37 ± 0.04 7.35 ± 0.03* 7.37 ± 0.07
36 ± 5 39 ± 9 41 ± 7* 39 ± 8
36 ± 9 38 ± 5 40 ± 6* 39 ± 5
148 ± 25 131 ± 21* 136 ± 25* R 121 ± 24*w 24 ± 8 25 ± 7 24 ± 9 23 ± 6
153 ± 25 135 ± 15* 138 ± 26* R 98 ± 18*w # 23 ± 7 22 ± 8 21 ± 6 22 ± 5
Data are shown as mean ± SD. Desufflation indicates 5 minutes after the abdomen was desufflated; induction, 5 minutes after anesthesia induction; insufflation, 5 minutes after the abdomen was insufflated; PaCO2, partial arterial carbon dioxide pressure; PaO2, partial arterial oxygen pressure; postoperative, 30 minutes after the operation. *P < 0.05 compared with induction period. RwP < 0.05 compared with insufflation period. P < 0.05 compared with desufflation period. #P < 0.05 between groups.
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TABLE 3. Respiratory Mechanics Cdyn (mL/cm H2O) Induction Insufflation Desufflation Raw (cm H2O/L/sec) Induction Insufflation Desufflation PIP (mm Hg) Induction Insufflation Desufflation
Group I (n = 16)
Group II (n = 16)
43 ± 13 34 ± 11* 42 ± 7w
42 ± 11 32 ± 8* 37 ± 11w#
16 ± 7 23 ± 7* 18 ± 8w
17 ± 5 22 ± 7* 17 ± 7w
18 ± 5 22 ± 8* 19 ± 7w
16 ± 6 23 ± 7* 17 ± 8w
Data are shown as mean ± SD. Cdyn indicates dynamic compliance; desufflation, 5 minutes after the abdomen was desufflated; induction, 5 minutes after anesthesia induction; insufflation, 5 minutes after the abdomen was insufflated; PIP, peak inspiratory pressure; Raw, resistance of airway. *P < 0.05 compared with induction period. wP < 0.05 compared with insufflation period. #P < 0.05 between groups.
significant. In group I, Cdyn values at the desufflation period were statistically significantly higher compared with those in group II.
DISCUSSION An alveolar recruitment method is useful for increasing arterial oxygenation and improving respiratory mechanics.9,14,15 This study examines the effects of the different oxygen concentrations used in RM during pneumoperitonium on respiratory mechanics and blood gas values. As estimated, we reached higher arterial blood gas oxygen pressures in the postoperative period in patients who were administered 30% oxygen during RM compared with the group that was given 100% oxygen during RM. After desufflation compliance also remained significantly higher in the 30% oxygen group. We propose that this is related to the atelectasis development owing to the high oxygen concentration. There are several RMs that have been defined. Generally, researchers report the pressure values and times that were used during the RM in detail but do not provide any information on the gas mixture used during recruitment. The most frequently used parameters are 15 seconds of positive pressure applied at 40 cm H2O.7 This is the pressure required for the generation of vital capacity and is termed the vital capacity maneuver. Rothen et al17 stated that a 7second application of pressure was adequate for the effectiveness of vital capacity maneuver. In another study, recruitment was made by selecting a 2-minute pressurecontrolled ventilation mode while using positive endexpiratory pressure (PEEP) at 20 cm H2O, such that the respiratory frequency was 12 breaths/min and the peak pressure was 40 cm H2O.18 The inspiratory time was set as 4 seconds and the expiratory time was set as 1 second (inspiration time:expiration time = 4:1). In addition, there are many studies that address the use of PEEP postmaneuver during anesthesia or in patients with acute lung injury to prevent the regeneration of atelectasia.7,19–21 The oxygen percentage was either not specified or kept at 100% in most of these studies, and the potential effects of high oxygen concentration were not assessed. However, high
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oxygen concentrations used during operation may have harmful effects. Absorption atelectasis may occur as oxygen, which replaces the less soluble nitrogen and leaves the alveoli in patients respiring oxygen for a long time at 80% to 100% concentrations. The inadequacy of the secretion excretion, replacement of nitrogen by volatile anesthetics, and the high oxygen concentration that is used during general anesthesia can lead to the development of resorption atelectasis after general anesthesia.22 Rothen and colleagues investigated the effects of the gas composition used during general anesthesia induction on the generation of atelectasis and gas exchange. The authors used 30% oxygen in one group and 100% oxygen in the other group during induction, and they concluded that the use of low oxygen concentrations prevents the generation of atelectasis in the early period.20 Edmark et al23 investigated optimum oxygen concentration values that would discourage the generation of atelectasis, keeping in consideration that the use of low oxygen concentrations during preoxygenation may increase the risk of hypoxemia during apnea. Oxygen concentrations of 80% and 60% were used during preoxygenation, and no increase was observed in the percentage of atelectasis in either of the groups. The apnea time when oxygen saturation was decreased to 90% was found to be >5 minutes in the 80% oxygen concentration group.23 Rothen et al24 published a study similar to ours in 1995. By using 40% and 100% oxygen concentrations in the RM in 12 brain surgery and general surgery cases, respectively, the authors assessed these patients in terms of atelectasis by computer tomography, blood gas assessments, and compliance measurements. The authors found that atelectasis developed in all patients after anesthesia induction, and this atelectasis was abolished with the RM in all patients. Furthermore, the authors determined that the amount of atelectasis was increased to a value closed to prerecruitment value 5 minutes after the RM with 100% oxygen, whereas there was a small increase in the amount of atelectasis, which reached about one sixth of the initial area of atelectasis 40 minutes after the RM with 40% oxygen. However, compliance changes showed no difference between groups and they found no correlation between compliance and atelectasis. The authors attributed this to the existence of factors other than atelectasis that could affect compliance. In our study, when compared with insufflation period, compliance increased in both groups in the desufflation period, which corresponds to the post-RM period; however, it did not reach the original value at the induction period in the group that was administered 100% oxygen. When compared with the aforementioned study, our patient group had higher risk for atelectasis because of laparoscopy. The fact that our study included only healthy patients with normal respiratory function may be considered a weakness. Studies that include patients, who are also susceptible to atelectasis (such as obesity) or patients with respiratory disease and who also have low PaO2 levels, may be of greater value. We conclude that oxygen concentration is as important as the pressure values and times used during RM when applied to prevent atelectasis. On the basis of our results, during RM it is reasonable to keep oxygen concentration at a level low enough to maintain SpO2 > 90%. The unfavorable results of redundant high oxygen concentrations during RM may not be clinically significant in healthy individuals, but patients who are vulnerable to low PaO2 levels may be impacted. Further studies are required to assess the optimum oxygen concentrations for RM that r
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should be used to prevent hypoxia in both healthy individuals and patients with comorbidities. Use of CT scan to determine the quantity and location of possible atelectasis and additional ventilation/perfusion studies and respiratory function analysis could be useful to evaluate the effects of RM with different oxygen concentrations. REFERENCES 1. Marshall BE, Wyche MQ Jr. Hypoxemia during and after anesthesia. Anesthesiology. 1972;37:178–209. 2. Hedenstierna G. Gas exchange during anesthesia. Br J Anaesth. 1990;64:507–514. 3. Andersson LE, Ba˚a˚th M, Tho¨rne A, et al. Effect of carbon dioxide pneumoperitoneum on development of atelectasis during anesthesia, examined by spiral computed tomography. Anesthesiology. 2005;102:293–299. 4. El-Dawlatly AA, Al-Dohayan A, Abdel-Meguid ME, et al. The effects of pneumoperitoneum on respiratory mechanics during general anesthesia for bariatric surgery. Obes Surg. 2004;14:212–225. 5. Nguyen NT, Wolfe BM. The physiologic effects of pneumoperitoneum in the morbidly obese. Ann Surg. 2005;241:219–226. 6. Salihoglu Z, Demiroluk S, Baca B, et al. Effects of pneumoperitoneum and positioning on respiratory mechanics in chronic obstructive pulmonary disease patients during Nissen fundoplication. Surg Laparosc Endosc Percutan Tech. 2008;18:437–440. 7. Rothen HU, Sporre B, Englberg G, et al. Re-expansion of atelectasis during general anesthesia: a computed tomography study. Br J Anaesth. 1993;71:788–795. 8. Tusman G, Bo¨hm SH, Vazquez de Anda GF, et al. “Alveolar recruitment strategy” improves arterial oxygenation during general anesthesia. Br J Anaesth. 1999;82:8–13. 9. Whalen FX, Gajic O, Thompson GB, et al. The effects of the alveolar recruitment maneuver and positive end-expiratory pressure on arterial oxygenation during laparoscopic bariatric surgery. Anesth Analg. 2006;102:298–305. 10. Cinnella G, Grasso S, Spadaro S, et al. Effects of recruitment maneuver and positive end-expiratory pressure on respiratory mechanics and transpulmonary pressure during laparoscopic surgery. Anesthesiology. 2013;118:114–122. 11. Talab HF, Zabani IA, Abdelrahman HS, et al. Intraoperative ventilatory strategies for prevention of pulmonary atelectasis in
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