Haemodynamic changes during low-pressure carbon dioxide pneumoperitoneum in young children

BACKGROUND: Both mechanical and pharmacological effects may contribute to the haemodynamic consequences of carbon dioxide (CO2) pneumoperitoneum. The aim of the present study was to evaluate the haemodynamic effects of low-pressure pneumoperitoneum [intra-abdominal pressure (IAP) 5 mmHg] in young children (< 3 years). METHODS: Thirteen children, aged 6-36 months, ASA physical status I-III, who were scheduled for laparoscopic fundoplication for gastro-oesophageal reflux were investigated in the head-up position (10 degrees ). Noninvasive thoracic electrical bioimpedance cardiac index (CI), stroke volume index (SVI), heart rate (HR), mean arterial pressure (MAP) and peak inspiratory pressure (PIP) were recorded, together with PetCO2 and PaCO2 at five time points: before insufflation, 20, 35 and 70 min after start of CO2 insufflation and 12 min after desufflation. During insufflation, minute ventilation was not adjusted and the IAP was maintained at 5 mmHg. RESULTS: During insufflation, PetCO2 increased from 29 +/- 4 to 37 +/- 5 mmHg (P < 0.001) and PaCO2 increased from 31 +/- 4 to 39 +/- 5 mmHg (P < 0.01). CI increased from 2.39 +/- 0.86 to 2.92 +/- 0.94 l x min-1 x m2 (P < 0.01), HR increased from 108 +/- 10 to 126 +/- 22 b x min-1 (P < 0.01), MAP increased from 52 +/- 10 to 63 +/- 9 (P < 0.05) and PIP increased from 16 +/- 3 to 18 +/- 3 cm H2O (P < 0.001). There were no changes in SVI and arterial oxygen saturation. CONCLUSIONS: We conclude that low-pressure CO2 pneumoperitoneum (with IAPs not exceeding 5 mmHg) for laparoscopic fundoplication in infants and children does not decrease their cardiac index.     

不同二氧化碳气腹压力对家兔心肌细胞的影响

目的　研究不同CO2 气腹压力对家兔心肌超微结构的影响。方法　 1 8只健康家兔 ,随机分为三组。A组气腹压力 1 0mmHg ,B组 1 5mmHg ,C组 2 0mmHg。用氯胺酮和地西泮肌注麻醉。测定气腹前和气腹后 30、6 0min的MAP、CVP ,HR ,测定同一时点的内皮素 (ET)、洋地黄物质(EDLS)和心肌酶谱。实验结束 ,取左室内壁心肌组织行电镜观察。结果　 (1 )血液动力学变化 :三组的HR组内、组间比较均无差异。CVP组内比较 ,三组气腹前与气腹后 30、6 0min ,差异非常显著(P <0 0 1 ) ;组间比较 ,气腹后 30、6 0min ,A组与B组、C组差异显著 (P <0 0 5 ) ,B组与C组间无差异。MAP组内比较 ,C组气腹前与气腹后 6 0min差异显著 (P <0 0 5 ) ;组间比较 ,A组与C组、B组与C组间差异显著 (P <0 0 5 )。 (2 )EDLS :组内组间均无差异 ,但气腹后 30、6 0min时的血浆水平比气腹前增加。 (3)ET :组内组间均无差异 ,但组内比较总体呈下降趋势。 (4 )心肌酶谱 :心肌酶随气腹时间的延长和压力的升高呈上升趋势。乳酸脱氢酶 (LDH) :B组气腹前与气腹后 6 0min比较差异显著 (P <0 0 5 )。天冬氨酸转移酶 (AST) :B组气腹前与气腹后 6 0min比较差异显著 (P <0 0 5 )。 (5 )心肌超微结构的变化 :A、B、C三组动物心肌组织均有不同程度的超微结     

Effect of intraabdominal pressure elevation and positioning on hemodynamic reponses during carbon dioxide pneumoperitoneum for laparoscopic donor nephrectomy: a prospective controlled clinical study

Background Carbon dioxide (CO₂) pneumoperitoneum (PP) increases mean arterial blood pressure (MAP) and systemic vascular resistance (SVR) but decreases stroke volume (SV) and cardiac output (CO). This study evaluated the hemodynamic effects of elevated intraabdominal pressure (IAP) occurring during laparoscopic donor nephrectomy (LDN).Methods Twenty-two patients undergoing LDN were investigated and hemodynamic parameters, P_vCO₂ (carbon dioxide partial pressure), and VCO₂ (carbon dioxide production) were monitored during the procedure. Before and after PP, IAP was raised from 12 to 20 mmHg and the hemodynamic effects were measured every 30 s.Results During IAP of 12 mmHg and stable serum CO₂, there was no change in SV compared to preinsufflation levels. When IAP was elevated from 12 to 20 mmHg, SV initially decreased (p < 05), followed by an increase in MAP and SVR (p < 0.05).Conclusion This study shows that with the fluid and ventilation protocol used, PP has no significant effect on SV at an IAP of 12 mmHg, whereas increasing IAP to 20 mmHg does. In this study, the hemodynamic effects induced by CO₂ PP of 12 mmHg are not due to changes in serum CO₂ . Compression of the venous system during a PP of 20 mmHg reduces preload, with an subsequent increase in SVR.     

Hemodynamic and Respiratory Effects of Robot-assisted Laparoscopic Fundoplication in Children

Laparoscopic fundoplication is increasingly used for treating gastro-esophageal reflux disease in children. Mechanical and pharmacological effects may contribute to hemodynamic and respiratory changes during carbon dioxide pneumoperitoneum. The aim of the present study was to evaluate the hemodynamic and respiratory effects of pneumoperitoneum (PP) with an intra-abdominal pressure (IAP) of 12 mmHg in children undergoing robot-assisted laparoscopic fundoplication during total intravenous anesthesia. Ten children, aged 8–16 years, American Society of Anesthesiologists physical status II–III, scheduled for robot-assisted laparoscopic fundoplication in the reverse Trendelenburg position were investigated. Minute ventilation (MV), peak inspiratory pressure (PIP), IAP, heart rate (HR), mean arterial blood pressure (MAP) were recorded, together with pH, base excess, HCO₃⁻, P_etCO₂, P_aCO₂, and P_aO₂ at six time points: before insufflation, 10, 30, 60, 90 minutes after creating PP and after desufflation. The IAP was maintained at 12 mmHg. During insufflation MAP increased significantly from 70.6 (±9.0) to 84.8 (±10.4) mmHg, MV was increased from 4.6 (±0.8) to 5.5 (±0.9) lmin⁻¹, PIP increased, P_aO₂ and pH decreased. P_etCO₂ increased from 33.1 (±1.6) to 36.6 (±1.6) mmHg together with P_aCO₂. Hemodynamic and respiratory effects due to the intra-abdominal insufflation of CO₂ with an IAP of 12 mmHg are well tolerated, and anesthesia with remifentanil, propofol and mivacurium facilitates extubation immediately at the end of surgery.     

CO2气腹对肝硬变大鼠门脉血流影响的实验研究

目的　探讨CO2 气腹对肝硬变大鼠门脉血流量的影响。　方法　制作肝硬变大鼠模型 ,施加不同压力的气腹 ,分别测平均动脉压、门静脉压力、下腔静脉压、门静脉血流 ,计算门静脉阻力。　结果　平均动脉压、下腔静脉压在不同气腹压力下无明显变化 ,两组大鼠门静脉压力在 10mmHg时出现显著差异 ,随着压力的升高而升高。正常大鼠的门静脉血流量在 2 0mmHg下与 0mmHg下比较有显著差异 ,而肝硬变大鼠的门静脉血流量在 10mmHg下与 0mmHg下比较已有显著差异。正常大鼠门静脉阻力随着压力的升高在 10mmHg时出现显著差异 ,以后继续升高 ,肝硬化大鼠门静脉阻力随着压力的升高持续升高。　结论　CO2 气腹致肝硬化大鼠门静脉血流减少 ,且减少程度重于正常大鼠     

Comparative analysis of the hemodynamic and respiratory parameters during laparoscopic versus open living donor nephrectomy: an experimental model

Increased intrabdominal pressure induced by pneumoperitoneum induces modifications in cardiovascular and respiratory systems. The aim of the study was to analyze the hemodynamic and respiratory modifications produced by pneumoperitoneum during living donor nephrectomy in a porcine experimental model. Twenty pigs underwent left nephrectomy, 10 by laparoscopy and 10 by an open approach. The following parameters were measured: mean arterial pressure (MAP), central venous pressure, cardiac output (CO), systemic vascular resistance (SVR), end tidal CO2 (ETCO2), minute volume (MV), respiratory airway pressure (RAP), and "compliance." Both groups were monitored for cardiac and respiratory systems at basal, 5, 30, and 60 minutes as well as postsurgery. The comparative analysis demonstrated increased CO with a higher difference at 30 minutes (4.33 +/- 0.73 vs 8.54 +/- 1.26 L/min, P < .001); decreased SVR (1118.81 +/- 302.52 vs 663.37 +/- 81.45 dinas x s x cm(-5), P < .001), and elevated MAP among the laparoscopic group (66.5 +/- 11.52 vs 80.25 +/- 2.49 mm Hg, P = .004). Analysis of respiratory modifications showed an initial increase in ETCO2 (44.3 +/- 2.6 vs 54.1 +/- 12.56 mm Hg, P < .035) and a higher MV administered (5.6 +/- 0.1 vs 7.01 +/- 0.96 L/min, P = .03) to the laparoscopy group. An increased RAP was observed at 5 minutes (22.11 +/- 2.76 vs 28.8 +/- 3.68 mm Hg, P < .001), in the laparoscopic group and lower levels of "compliance" at the same moment in that group (16 +/- 1.66 vs 14.9 +/- 4.07 cm H2O). Laparoscopic nephrectomy caused an increase in CO and MAP and decreased SVR. Likewise there were elevations of RAP, ETCO2, and MV and a slight decrease in the "compliance."     

Resuscitation fluid volume and abdominal compartment syndrome in patients with major burns

Abdominal compartment syndrome (ACS) is rarely reported as a complication of severe burn. This study clarified the risk of burned patients with and without ACS, especially regarding the resuscitation fluid volume. Extensively burned patients admitted to our burn unit from January 2003, through to June 2004, were examined. Vital signs, blood gas analysis, bladder pressure to estimate intra-abdominal pressure (IAP), peak inspiratory pressure (PIP), resuscitation fluid volume, and urine output (UO) were analyzed. Intra-abdominal hypertension (IAH) was defined as an IAP of more than 30 cm of H2O. Eight of 48 patients suffering from a more than 30% total burn surface area developed ACS in 18.3+/-4.9 h. In these patients, IAP (49+/-12 cmH2O), PIP (50+/-16 cmH2O), heart rate (115+/-8/min), and PaCO2 (54.6+/-10.1 mmHg) were higher than normal, and their resuscitation volume was 0.40+/-0.11 L/kg. Also, a significant correlation between the IBP, PIP and resuscitation volume was observed. Most patients with severe burns required more than 300 mL/kg of resuscitation fluid for the first 24 h after injury that led to ACS and had higher HR, IBP, PIP and PaCO2 despite arterial pressure showing no significant difference.     

The optimum pneumoperitoneum pressure for laparoscopic surgery in the rat model

Background: There is increasing interest in the rat model of laparoscopic surgery. This study evaluates the cardiorespiratory effects of increasing CO₂ pneumoperitoneum (PP) in the rat. Methods: Nine Sprague-Dawley rats were subjected to CO₂ PP at pressures of 2, 5, 10, and 15 mmHg or control (no PP) under anesthesia. Catheters were placed in the femoral artery and the jugular vein to measure heart rate (HR), blood pressure (MAP), and arterial pH, PCO₂, PO₂, and HCO₃. A thermistor probe in the aortic arch measured cardiac output (CO) and blood temperature (BT). Results: CO₂ PP had no effect on CO, MAP, or BT at any pressure. CO₂ PP greater than 5 mmHg caused significant bradycardia and CO₂ PP greater than 10 mmHg caused significant respiratory acidosis. Conclusions: CO₂ PP pressures above 10 mmHg in rat should be avoided when performing laparoscopic surgery in the rat model.     

Effects of increased intra-abdominal pressure and volume expansion on renal function in the rat.

BACKGROUND: The effects of increased intra-abdominal pressure (IAP) and volume expansion on renal function in the rat were studied to gain more knowledge of the oliguria seen during laparoscopic procedures and to reduce the detrimental renal effects of IAP. METHODS: IAP was elevated to 5 or 10 mmHg by insufflation of CO(2) and maintained for 2 h in anaesthetized and mechanically ventilated rats. Rats with normal IAP served as controls. An angiotensin II receptor I antagonist, candesartan, was given as a bolus injection and a 5% volume expansion was achieved by i.v. saline infusion. An angiotensin-converting enzyme (ACE) inhibitor was also given. Renal parameters were the glomerular filtration rate (GFR), urine production, the urinary concentrations of sodium and potassium and the osmolality in the urine. The arterial acid-base balance and blood pressure were also monitored. RESULTS: The GFR deteriorated by 70% during pneumoperitoneum (PP) of 10 mmHg. There was a dramatic drop in sodium excretion (88-97%). With candesartan and elevated IAP, there was a drop in mean arterial pressure (from 90 to 55 mmHg) and the negative renal effects were very pronounced. Renal function was better preserved during elevated IAP in combination with volume expansion. CONCLUSIONS: Capnoperitoneum suppresses renal function, especially in combination with angiotensin II receptor 1 blockade and ACE inhibition. Volume expansion reduces the deleterious effects of PP on renal function during elevated IAP. The results suggest that patients should not be given pharmaceuticals blocking the renin-angiotensin-aldosterone system prior to procedures that may increase IAP. It may be beneficial, however, to reduce angiotensin II tension by volume expansion.     

The effect of insufflation pressure on pulmonary mechanics in infants during laparoscopic surgical procedures

BACKGROUND: Few studies have reported objective measurements of pulmonary changes under controlled conditions in infants undergoing laparoscopic procedures. We objectively measured the pulmonary effects of laparoscopically-induced pneumoperitoneum in infants less than 1 year of age undergoing surgical procedures under general anaesthesia. METHODS: Nineteen ASA I-II patients less than 1 year of age were enrolled in this direct observational study. Anaesthetic technique included inhalation induction using sevoflurane/O2/air and neuromuscular blockade. Infants were ventilated using 10-15 ml.kg-1 tidal volume at a respiratory rate sufficient to achieve normocarbia [PECO2 4.6-5.8 kPa (35-45 mmHg)]. Opioids and regional anaesthesia techniques were used when appropriate. Peak inspiratory pressure (PIP), expiratory tidal volume (Vt), endtidal carbon dioxide concentration (PECO2) and dynamic compliance (COMPdyn) were recorded at baseline, 5, 10 mmHg and maximal insufflation pressure (Pmax). Pmax was limited to 12 mmHg for infants <5 kg, 15 mmHg for infants >5 kg. At steady state Pmax, ventilator changes were implemented to restore Vt and PECO2 to within 10% of baseline. Each patient served as his own control. RESULTS: At Pmax, average PIP increased 18%, average Vt decreased 33%, average PECO2 concentration increased 13%, average COMPdyn decreased 48%; O2 saturation fell in 41% of patients. Twenty ventilator adjustments were required; one patient experienced no changes in measured pulmonary mechanics, requiring no ventilator changes. CONCLUSIONS: Pulmonary mechanics in infants change significantly during laparoscopic CO2 pneumoperitoneum; the magnitude of change correlates directly with intraperitoneal pressure. Greater than 90% of infants required at least one ventilatory intervention to restore baseline Vt and PECO2.     

Inert gas exchange during pneumoperitoneum at incremental values of positive end-expiratory pressure

Laparoscopy is a surgical technique for a growing variety of abdominal operations. In patients undergoing this procedure, arterial blood oxygenation and hemodynamics are frequently depressed. This study evaluated the effect of different levels of positive end-expiratory pressure (PEEP) during intraperitoneal CO(2) insufflation on the lung's ventilation-perfusion distribution in a porcine model. We studied 13 anesthetized pigs with an intraperitoneal pressure of 15 cm H(2)O applied at either incremental values of PEEP (5-20 cm H(2)O, increments of 5 cm H(2)O) or a constant PEEP of 5 cm H(2)O. The effects of CO(2) pneumoperitoneum on inert gas exchange and hemodynamics were examined with the multiple inert gas elimination technique. During pneumoperitoneum, gas exchange was most augmented by 15 and 20 cm H(2)O of PEEP. Although the differences in hemodynamics between the individual settings were insignificant, 10 cm H(2)O of PEEP provided the smallest impairment of hemodynamics. We conclude that PEEP of 15 H(2)O during pneumoperitoneum resulted in a modest hemodynamic depression but significant gas exchange augmentation in our experiment. IMPLICATIONS: Anesthetized pigs, with a pneumoperitoneum of 15 cm H(2)O, were treated either with incremental values of positive end-expiratory pressure (5-20 cm H(2)O, increments of 5 cm H(2)O) or with a constant positive end-expiratory pressure of 5 cm H(2)O. Fifteen and 20 cm H(2)O resulted in significantly improved pulmonary gas exchange compared with 5 cm H(2)O.     

Effects of the Beach Chair Position, Positive End-expiratory Pressure, and Pneumoperitoneum on Respiratory Function in Morbidly Obese Patients during Anesthesia and Paralysis

Background: The authors studied the effects of the beach chair (BC) position, 10 cm H2O positive end-expiratory pressure (PEEP), and pneumoperitoneum on respiratory function in morbidly obese patients undergoing laparoscopic gastric banding.

Methods: The authors studied 20 patients (body mass index 42 +/- 5 kg/m2) during the supine and BC positions, before and after pneumoperitoneum was instituted (13.6 +/- 1.2 mmHg). PEEP was applied during each combination of position and pneumoperitoneum. The authors measured elastance (E,rs) of the respiratory system, end-expiratory lung volume (helium technique), and arterial oxygen tension. Pressure-volume curves were also taken (occlusion technique). Patients were paralyzed during total intravenous anesthesia. Tidal volume (10.5 +/- 1 ml/kg ideal body weight) and respiratory rate (11 +/- 1 breaths/min) were kept constant throughout.

Results: In the supine position, respiratory function was abnormal: E,rs was 21.71 +/- 5.26 cm H2O/l, and end-expiratory lung volume was 0.46 +/- 0.1 l. Both the BC position and PEEP improved E,rs (P < 0.01). End-expiratory lung volume almost doubled (0.83 +/- 0.3 and 0.85 +/- 0.3 l, BC and PEEP, respectively; P < 0.01 vs. supine zero end-expiratory pressure), with no evidence of lung recruitment (0.04 +/- 0.1 l in the supine and 0.07 +/- 0.2 in the BC position). PEEP was associated with higher airway pressures than the BC position (22.1 +/- 2.01 vs. 13.8 +/- 1.8 cm H2O; P < 0.01). Pneumoperitoneum further worsened E,rs (31.59 +/- 6.73; P < 0.01) and end-expiratory lung volume (0.35 +/- 0.1 l; P < 0.01). Changes of lung volume correlated with changes of oxygenation (linear regression, R2 = 0.524, P < 0.001) so that during pneumoperitoneum, only the combination of the BC position and PEEP improved oxygenation.     

Impact of carbon dioxide and helium insufflation on cardiorespiratory function during prolonged pneumoperitoneum in an experimental rat model

BACKGROUND: Experimental studies on laparoscopic surgery are often performed in rats. However, the hemodynamic and respiratory responses related to the pneumoperitoneum have not been studied extensively in rats. Therefore, the aim of this study was to investigate in spontaneously breathing rats the effects of CO2 and helium, insufflation pressure, and duration of pneumoperitoneum on blood pressure, arterial pH, pCO2, pO2, HCO3-, base excess, and respiratory rate. METHODS: Five groups of 9 Brown Norway rats were anesthetized and underwent CO2 insufflation (6 or 12 mmHg), helium insufflation (6 or 12 mmHg), or abdominal wall lifting (gasless control) for 120 min. Blood pressure was monitored by an indwelling carotid artery catheter. Baseline measurements of mean arterial pressure (MAP), respiratory rate, arterial blood pH, pCO2, pO2, HCO3-, and base excess were recorded. Blood gases were analyzed at 5, 30, 60, 90, and 120 min during pneumoperitoneum, and MAP and respiratory rate were recorded at 5 and 15 min and at 15-min intervals thereafter for 2 h. RESULTS: CO2 insufflation (at both 6 and 12 mmHg) caused a significant decrease in blood pH and increase in arterial pCO2. Respiratory compensation was evident since pCO2 returned to preinsufflation levels during CO2 insufflation at 12 mmHg. There was no significant change in blood pH and pCO2 in rats undergoing either helium insufflation or gasless procedures. Neither insufflation pressure nor the type of insufflation gas had a significant effect on MAP over time. CONCLUSION: The cardiorespiratory changes during prolonged pneumoperitoneum in spontaneously breathing rats are similar to those seen in clinical practice. Therefore, studies conducted in this animal model can provide valuable physiological data relevant to the study of laparoscopic surgery.     

Prospective randomized clinical trial comparing nitrous oxide and carbon dioxide pneumoperitoneum for laparoscopic surgery

BACKGROUND: Recent publications demonstrating the safety and advantages of N2O for pneumoperitoneum (PP) prompted us to reconsider N2O as an agent for PP in general surgical laparoscopy. The purpose of this prospective, double-blind, randomized clinical trial was to determine whether N2O PP has any benefits over CO2 PP. STUDY DESIGN: One hundred three patients received N2O (group I, n = 52) or CO2 (group II, n = 51) PP for elective laparoscopic surgery. Heart rate, mean arterial blood pressure, end-tidal CO2, minute ventilation, and O2 saturation were recorded before PP, during PP, and in the recovery room. Postoperative pain medication use was recorded. Pain was assessed by means of visual analog scale (VAS) at postoperative hours 2 and 4, and on day 1. RESULTS: There were no differences between groups I and II in patient age, gender, weight, anesthesia risk (American Society of Anesthesiologists Score > 2), operative time, duration of PP, or length of hospital stay. Mean end-tidal CO2 increase under anesthesia was greater in group II than group I (3.0 versus 0.5 mmHg, p < 0.001) despite a greater mean intraoperative increase in minute ventilation in group II than group I (0.7 versus -0.2 L/min p < 0.001). The patients who had N2O PP had less pain 2 hours postoperatively (VAS: 4.9 versus 5.7, p <0.05), 4 hours postoperatively (VAS: 3.3 versus 5.1, p < 0.01), and 1 day postoperatively (VAS: 1.7 versus 3.5, p < 0.01) than patients who had CO2 PP. Postoperative narcotic or ketorolac use was not statistically different between groups. There were no adverse events related to either N2O or CO2 pneumoperitoneum. CONCLUSIONS: These results suggest that the use of N2O PP has sufficient advantages over CO2 that it should be considered as the standard agent for therapeutic PP.     

Effects of the beach chair position, positive end-expiratory pressure, and pneumoperitoneum on respiratory function in morbidly obese patients during anesthesia and paralysis

BACKGROUND: The authors studied the effects of the beach chair (BC) position, 10 cm H2O positive end-expiratory pressure (PEEP), and pneumoperitoneum on respiratory function in morbidly obese patients undergoing laparoscopic gastric banding. METHODS: The authors studied 20 patients (body mass index 42 +/- 5 kg/m2) during the supine and BC positions, before and after pneumoperitoneum was instituted (13.6 +/- 1.2 mmHg). PEEP was applied during each combination of position and pneumoperitoneum. The authors measured elastance (E,rs) of the respiratory system, end-expiratory lung volume (helium technique), and arterial oxygen tension. Pressure-volume curves were also taken (occlusion technique). Patients were paralyzed during total intravenous anesthesia. Tidal volume (10.5 +/- 1 ml/kg ideal body weight) and respiratory rate (11 +/- 1 breaths/min) were kept constant throughout. RESULTS: In the supine position, respiratory function was abnormal: E,rs was 21.71 +/- 5.26 cm H2O/l, and end-expiratory lung volume was 0.46 +/- 0.1 l. Both the BC position and PEEP improved E,rs (P < 0.01). End-expiratory lung volume almost doubled (0.83 +/- 0.3 and 0.85 +/- 0.3 l, BC and PEEP, respectively; P < 0.01 vs. supine zero end-expiratory pressure), with no evidence of lung recruitment (0.04 +/- 0.1 l in the supine and 0.07 +/- 0.2 in the BC position). PEEP was associated with higher airway pressures than the BC position (22.1 +/- 2.01 vs. 13.8 +/- 1.8 cm H2O; P < 0.01). Pneumoperitoneum further worsened E,rs (31.59 +/- 6.73; P < 0.01) and end-expiratory lung volume (0.35 +/- 0.1 l; P < 0.01). Changes of lung volume correlated with changes of oxygenation (linear regression, R2 = 0.524, P < 0.001) so that during pneumoperitoneum, only the combination of the BC position and PEEP improved oxygenation. CONCLUSIONS: The BC position and PEEP counteracted the major derangements of respiratory function produced by anesthesia and paralysis. During pneumoperitoneum, only the combination of the two maneuvers improved oxygenation.     

Hemodynamic and pulmonary changes during open, carbon dioxide pneumoperitoneum, and abdominal wall-lifting cholecystectomy

Background: Carbon dioxide (CO2) pneumoperitoneum effects are still controversial. The aim of this study was to investigate cardiopulmonary changes in patients subjected to different surgical procedures for cholecystectomy. Methods: In this study, 15 patients were assigned randomly to three groups according to the surgical procedure to be used: open cholecystectomy (OC), CO2 pneumoperitoneum cholecystectomy (PP), and laparoscopic gasless cholecystectomy (abdominal wall lifting [AWL]), respectively. A pulmonary artery catheter was used for hemodynamic monitoring in all patients. A subcutaneous multiplanar device (Laparo Tenser) was used for abdominal wall lifting. To avoid misinterpretation of results, conventional anesthesia was performed with all parameters, and the position of the patients held fixed thoroughout surgery. The following parameters were analyzed: mean arterial pressure (MAP), heart rate (HR), cardiac output (CO), cardiac index (CI), stroke volume index (SVI), central venous pressure (CVP), systemic vascular resistances index (SVRI), mean pulmonary arterial pressure (MPAP), pulmonary capillary wedge pressure (PCWP), pulmonary vascular resistances index (PVRI), peak inspiratory pressure (PIP), end-tidal CO2 pressure (ETCO)2, CO2 arterial pressure (PaCO2), and arterial pH. Results: All the operations were completed successfully. The Laparo Tenser allowed good exposition of the surgical field. A slight impairment of the cardiopulmonary functions, with reduction of SVRI, MAP, and CI and elevation of pulmonary pressures and vascular resistance, followed induction of anesthesia. However, these effects tended to normalize in the OC and AWL groups over time. In contrast, CO2 insufflation produced a complex hemodynamic and pulmonary syndrome resulting in increased right- and left side filling pressures, significant cardiac index reduction, derangement of the respiratory mechanics, and respiratory acidosis. All of these effects normalized after desufflation. Conclusions: Cardiopulmonary adverse effects of general anesthesia were significant but transitory and normalized during surgery. Carbon dioxide pneumoperitoneum caused a significant impairment in cardiopulmonary functions. In high-risk patients, gasless laparoscopy may be preferred for reliability and absence of cardiopulmonary alterations. apd: 21 December 2000     

Pneumoperitoneum versus abdominal wall lift: effects on central haemodynamics and intrathoracic pressure during laparoscopic cholecystectomy

BACKGROUND: It has been shown repeatedly that laparoscopic cholecystectomy using pneumoperitoneum (CO2 insufflation) may be associated with increased cardiac filling pressures and an increase in blood pressure and systemic vascular resistance. In the present study, the effects on the central circulation during abdominal wall lift (a gasless method of laparoscopic cholecystectomy) were compared with those during pneumoperitoneum. The study was also aimed at elucidating the relationships between the central filling pressures and the intrathoracic pressure. METHODS: Twenty patients (ASA I), scheduled for laparoscopic cholecystectomy, were randomised into two groups, pneumoperitoneum or abdominal wall lift. Measurements were made by arterial and pulmonary arterial catheterization before and during pneumoperitoneum or abdominal wall lift with the patient in the horizontal position. Measurements were repeated after head-up tilting the patients as well as after 30 min head-up tilt. The intrathoracic pressure was monitored in the horizontal position before and during intervention using an intraesophageal balloon. RESULTS: After pneumoperitoneum or abdominal wall lifting there were significant differences between the two groups regarding MAP, SVR, CVP, CI, and SV. Analogous to previous studies, in the pneumoperitoneum group CVP, PCWP, MPAP, and MAP as well as SVR were increased after CO2 insufflation (P < 0.01), while CI and SV were not affected. In contrast, in the abdominal wall lift group, CI and SV were significantly increased (P < 0.01), as was MAP (P < 0.01), while CVP, PCWP, MPAP, and SVR were not significantly affected. There was a significant difference in intraesophageal pressure between the two groups. In the pneumoperitoneum group, the intraesophageal pressure was increased by insufflation (P < 0.01) while, in the abdominal wall lift group, it was unaffected. In the pneumoperitoneum group the mean increases in cardiac filling pressures were of the same magnitude as the mean increase in the intraesophageal pressure. CONCLUSIONS: In healthy patients, abdominal wall lift increased cardiac index while pneumoperitoneum did not. Cardiac filling pressures and systemic vascular resistance were increased by pneumoperitoneum but unaffected by abdominal wall lift. The recorded elevated cardiac filling pressures during pneumoperitoneum may be only a reflection of the increased intra-abdominal pressure.     

不同CO_2气腹压力对腹腔镜下治疗胃癌的临床效果的影响

目的考察不同CO_2气腹压力对腹腔镜下治疗胃癌的临床效果的影响。方法选取2015年3月至2016年3月行腹腔镜下胃癌根治术的患者87例进行前瞻性研究。根据患者在腹腔镜手术中CO_2的气腹压力,随机分为低CO_2气腹组(7~9 mm Hg,29例)、中CO_2气腹组(10~12 mm Hg,29例)和高CO_2气腹组(13~15 mm Hg,29例),分别监测患者在气腹前(T0)、气腹后1 h(T1)、气腹后2 h(T2)和气腹停止后1 h(T3)各时间点三组患者的平均动脉压(MAP)、心率(HR)、酸碱度(pH)、动脉血二氧化碳分压(Pa CO_2)、动脉血氧分压(Pa O_2)、胱抑素C(Cys-C)和尿量。采用SPSS 17.0版软件对所有数据进行分析,术中相关指标及各时间点HR、MAP、pH、Pa CO_2、Pa O_2、Cys-C和尿量的变化,均以均数±标准差(x珋±s)的形式表示,组间比较采用t检验;计数资料采用χ2检验;以P0.05表示差异有统计学意义。结果与各组T0时间点和低CO_2气腹组相比,中、高CO_2气腹组T1至T3时间点的HR、MAP、Pa CO_2和Cys-C均显著升高,而尿量显著降低,差异具有统计学意义P0.05。结论低CO_2气腹压力对行腹腔镜治疗胃癌患者术中的循环和呼吸系统影响最小,并且可显著减轻气腹压力对肾功能的损伤,临床效果好、可推广应用于临床。     

The effects of tidal volume and respiratory rate on oxygenation and respiratory mechanics during laparoscopy in morbidly obese patients

Morbidly obese (MO) patients undergoing laparoscopy have lower PaO(2) compared with normal-weight (NW) patients. We hypothesized that increases in tidal volume (V(T)) or respiratory rate (RR) would improve oxygenation. All measurements were performed at: 1) baseline: V(T) 600-700 mL and 10 breaths/min, 2) double V(T): V(T) 1200-1400 mL and 10 breaths/min, and 3) double rate: V(T) 600-700 mL and 20 breaths/min. We calculated static respiratory system compliance (Cst,rs) and inspiratory resistance (RI,rs). End-tidal CO(2) was measured with a mass spectrometer, and PaO(2) and PaCO(2) with a continuous blood gas monitor. Supine anesthetized MO patients had 29% lower Cst,rs than the NW patients (P < 0.05). Positioning patients head-up or head-down before pneumoperitoneum did not significantly affect Cst,rs in either group (P = 0.8). Doubling the V(T), but not RR, increased Cst,rs in both groups. Pneumoperitoneum caused large decreases in Cst,rs in both groups (both P < 0.001). During pneumoperitoneum, changing the body position, V(T), or RR did not further affect Cst,rs in either group (P > 0.7). Before pneumoperitoneum, RI,rs was higher in the MO patients compared with the NW patients regardless of body position (P = 0.01). Doubling either RR or V(T) before pneumoperitoneum did not change RI,rs in either group. After pneumoperitoneum, RI,rs increased in both the head-down and head-up positions (P < 0.05), but not in the supine position. Regardless of the conditions studied, alveolar-arterial difference in oxygen tension was always significantly higher in MO patients (P < 0.05). The alveolar-arterial difference in oxygen tension was not affected by body position, pneumoperitoneum, or the mode of ventilation. Arterial oxygenation during laparoscopy was affected only by body weight and could not be improved by increasing either the V(T) or RR. IMPLICATIONS: Morbid obesity decreases arterial oxygenation and respiratory system compliance. During laparoscopy, arterial oxygenation is affected only by the patient's body weight. Increases in tidal volume or respiratory rate do not improve arterial oxygenation.     

Anaesthesia for laparoscopic surgery in paediatrics

Laparoscopic surgery is an emerging procedure in the treatment of many surgical pathologies. Laparoscopy in the paediatric patient reduces surgical trauma and improves cosmetic RESULTS. Physiological changes during laparoscopic surgery are mainly related to the increased intra-abdominal pressure (IAP) associated with CO2 insufflation of the abdomen, the patient's postural modifications (head-up or head-down) and CO2 absorption and its general effects. Increases in IAP affect both ventilation and circulation. Increased IAP induces a mechanical compression of the diaphragm that reduces pulmonary compliance, vital capacity, functional residual capacity (FRC) and total lung volume. Pneumoperitoneum in children has a major impact on cardiac volumes and function, mainly through the effect on ventricular load conditions. The acute increase in IAP affects both preload and afterload, while the systolic cardiac performance remains unchanged. During anaesthesia for videolaparoscopy it is important not to exceed an intrabdominal pressure of 6 mmHg in newborns and infants and 12 mmHg in older children. In our clinical experience the respiratory, cardiocirculatory and temperature parameters have been slightly influenced during laparoscopy, but have always been maintained within the normal ranges. Laparoscopic videosurgery in newborns, infants and paediatric age group patients can be performed safely and with satisfactory clinical results.