Positive end-expiratory pressure improves arterial oxygenation during prolonged pneumoperitoneum

The safety of CO2 pneumoperitoneum for elderly patients during laparoscopic colorectal surgery

OBJECTIVE

The aim of this study was to compare the anesthetic outcomes of elderly and younger patients perioperatively, and to evaluate the safety of this procedure in elderly.

METHODS

A total of 25 patients undergoing elective laparoscopic colorectal surgery were enrolled in this study prospectively. Ten patients were more than or equal to 70 years (Group E) and 15 patients were less than or equal to 69 years (Group Y). The parameters between groups for perioperative hemodynamics, arterial blood chemistry, and perfusion of intraabdominal organs were recorded and compared periodically from before induction of anesthesia till after the operation.

RESULTS

Group E had a higher ASA degree (P<0.01) than group Y. During the operation, the HCO3 and PaCO2 value increased whereas the pH value decreased significantly. All these parameters recovered gradually at the end of the surgery; some serum electrolytes decreased, especially K and Ca. The central venous pressure increased after volume expansion and the beginning of operation, and then decreased postoperatively. Mean arterial pressure had a marked change during volume expansion period and early after the induction of anesthesia. pHi decreased when the operation began. PgCO2 increased significantly at the end of the surgery. Central venous pressure of group E was higher than that of group Y at 5 minutes during operation, whereas mean arterial pressure of elder group was lower than that of younger group at 15 minutes after the end of operation. Other hemodynamic parameters did not differ significantly from the results.

CONCLUSION

There is no significantly adverse effect for elderly patients during perioperative period. Adequate intraoperative administration and monitoring are beneficial for maintaining a safe anesthesia.

Hemodynamic perturbations during robot-assisted laparoscopic radical prostatectomy in 45° Trendelenburg position

BACKGROUND

Robot-assisted laparoscopic radical prostatectomy has gained widespread use. However, circulatory effects in patients subjected to an extreme Trendelenburg position (45°) are not well characterized.

METHODS

We studied 16 patients (ASA physical status I-II) with a mean age of 59 years scheduled for robot-assisted laparoscopic radical prostatectomy (45° head-down tilt, with an intraabdominal pressure of 11-12 mm Hg). Hemodynamics, echocardiography, gas exchange, and ventilation-perfusion distribution were investigated before and during pneumoperitoneum, in the Trendelenburg position and, in 8 of the patients, also after the conclusion of surgery.

RESULTS

In the 45° Trendelenburg position, central venous pressure increased almost 3-fold compared with the initial value, with an associated 2-fold increase in mean pulmonary artery pressure and pulmonary capillary wedge pressure (P<0.01). Mean arterial blood pressure increased by 35%. Heart rate, stroke volume, cardiac output, and mixed venous oxygen saturation were unaffected during surgery, as were echocardiographic heart dimensions. After induction of anesthesia, isovolumic relaxation time was prolonged, with no further change during the study. Deceleration time was normal and stable. In the horizontal position after pneumoperitoneum exsufflation, filling pressures and mean arterial blood pressure returned to baseline levels. Pneumoperitoneum reduced lung compliance by 40% (P<0.01). Addition of the Trendelenburg position caused a further decrease (P<0.05). Arterial blood acid-base balance was normal. End-tidal carbon dioxide tension increased whereas arterial carbon dioxide was unaffected with unchanged ventilation settings. Pneumoperitoneum increased PaO2 (P<0.05). Ventilation-perfusion distribution, shunt, and dead space were unaltered during the study.

CONCLUSIONS

Pneumoperitoneum and 45° Trendelenburg position caused 2- to 3-fold increases in filling pressures, without effects on cardiac performance. Filling pressures were normalized immediately after surgery. Lung compliance was halved. Gas exchange was unaffected. No perioperative cardiovascular complications occurred.

Positive end-expiratory pressure (PEEP) during anaesthesia for the prevention of mortality and postoperative pulmonary complications

BACKGROUND

General anaesthesia causes atelectasis which can lead to impaired respiratory function. Positive end-expiratory pressure (PEEP) is a mechanical manoeuvre which increases functional residual capacity (FRC) and prevents collapse of the airways thereby reducing atelectasis. It is not known whether intra-operative PEEP alters the risk of postoperative mortality and pulmonary complications.

OBJECTIVES

To assess the benefits and harms of intraoperative PEEP, for all adult surgical patients, on postoperative mortality and pulmonary outcomes.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2009, Issue 4), MEDLINE (via Ovid) (1966 to January 2010), EMBASE (via Ovid) (1980 to January 2010), CINAHL (via EBSCOhost) (1982 to January 2010), ISI Web of Science (1945 to January 2010) and LILACS (via BIREME interface) (1982 to January 2010).

SELECTION CRITERIA

We included randomized clinical trials that evaluated the effect of PEEP versus no PEEP, during general anaesthesia, on postoperative mortality and postoperative respiratory complications. We included studies irrespective of language and publication status.

DATA COLLECTION AND ANALYSIS

Two investigators independently selected papers, extracted data that fulfilled our outcome criteria and assessed the quality of all included trials. We undertook pooled analyses, where appropriate. For our primary outcome (mortality) and two secondary outcomes (respiratory failure and pneumonia), we calculated the number of further patients needed (information size) in order to make reliable conclusions.

MAIN RESULTS

We included eight randomized trials with a total of 330 patients. Two trials had a low risk of bias. There was no difference demonstrated for mortality (relative risk (RR) 0.95, 95% CI 0.14 to 6.39). Two statistically significant results were found: the PEEP group had a higher PaO(2)/FiO(2) on day 1 postoperatively (mean difference (MD) 22.98, 95% CI 4.40 to 41.55) and postoperative atelectasis (defined as an area of collapsed lung, quantified by computerized tomography (CT) scan) was less in the PEEP group (SMD -1.2, 95% CI -1.78 to -0.79). There were no adverse events reported in the three trials that adequately measured these outcomes (barotrauma and cardiac complications). Using information size calculations, we estimated that a further 21,200 patients would need to be randomized in order to make a reliable conclusion about PEEP and mortality.

AUTHORS' CONCLUSIONS

There is currently insufficient evidence to make conclusions about whether intraoperative PEEP alters the risk of postoperative mortality and respiratory complications among undifferentiated surgical patients.

Management of mechanical ventilation during laparoscopic surgery

Laparoscopy is widely used in the surgical treatment of a number of diseases. Its advantages are generally believed to lie on its minimal invasiveness, better cosmetic outcome and shorter length of hospital stay based on surgical expertise and state-of-the-art equipment. Thousands of laparoscopic surgical procedures performed safely prove that mechanical ventilation during anaesthesia for laparoscopy is well tolerated by a vast majority of patients. However, the effects of pneumoperitoneum are particularly relevant to patients with underlying lung disease as well as to the increasing number of patients with higher-than-normal body mass index. Moreover, many surgical procedures are significantly longer in duration when performed with laparoscopic techniques. Taken together, these factors impose special care for the management of mechanical ventilation during laparoscopic surgery. The purpose of the review is to summarise the consequences of pneumoperitoneum on the standard monitoring of mechanical ventilation during anaesthesia and to discuss the rationale of using a protective ventilation strategy during laparoscopic surgery. The consequences of chest wall derangement occurring during pneumoperitoneum on airway pressure and central venous pressure, together with the role of end-tidal-CO2 monitoring are emphasised. Ventilatory and non-ventilatory strategies to protect the lung are discussed.

Positive end-expiratory pressure in pressure-controlled ventilation improves ventilatory and oxygenation parameters during laparoscopic cholecystectomy

BACKGROUND

During laparoscopy, pneumoperitoneum may result in intraoperative atelectasis, which impairs normal gas exchange. This study investigated whether positive end-expiratory pressure (PEEP) of 5 cmH(2)O in pressure-controlled ventilation (PCV) mode can improve ventilatory and oxygenation parameters during pneumoperitoneum.

METHODS

Thirty patients, aged 18-65 years, undergoing laparoscopic cholecystectomy were randomly allocated to the ZEEP (PEEP = 0 cmH(2)O) or PEEP (PEEP = 5 cmH(2)O) group. PCV was started after induction of anesthesia. Apart from PEEP level, all other ventilator settings were identical for both groups. Peak airway pressure was set at induction and reset after pneumoperitoneum to deliver tidal volume of 8 ml/kg in both groups. Hemodynamic, ventilatory, and oxygenation parameters were measured after induction of anesthesia (T1) and 30 min after pneumoperitoneum (T2).

RESULTS

Oxygenation index (PaO(2)/FiO(2)) was significantly higher in the PEEP group than in the ZEEP group at T2 (P = 0.031). In both groups, dynamic compliance significantly decreased over 40 min from T1 to T2. There were no significant differences in hemodynamics between the two groups during the study period.

CONCLUSION

Application of PEEP of 5 cmH(2)O should be considered in PCV during laparoscopic surgeries to decrease intraoperative atelectasis caused by pneumoperitoneum to improve gas exchange and oxygenation.

Perioperative management of patients with cytoreductive surgery for peritoneal carcinomatosis

Cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (HIPEC) has become an important tool in the management of patients with peritoneal malignancies. It is a complex surgical procedure with significant fluid loss during debulking leading to relevant pathophysiological alterations and therefore a challenge for anesthesiologists and critical care physicians. This review summarizes perioperative changes in hemodynamics, oxygen supply, coagulation, hematopoetic parameters and fluid status during cytoreductive surgery and HIPEC and how to deal with these pathophysiological alterations.

Beneficial effects of high positive end-expiratory pressure in lung respiratory mechanics during laparoscopic surgery

BACKGROUND

The effect of neuromuscular blockade (NMB) and positive end-expiratory pressure (PEEP) on the elastic properties of the respiratory system during pneumoperitoneum (PnP) remains a controversial subject. The main objective of the present study was to evaluate the effects of NMB and PEEP on respiratory mechanics.

METHODS

We performed a dynamic analysis of respiratory mechanics in patients subjected to PnP. Twenty-one patients underwent cholecystectomy videolaparoscopy and total intravenous anesthesia. The respiratory system resistance (R(RS)), pulmonary elastance (E(P)), chest wall elastance (E(CW)), and respiratory system elastance (E(RS)) were computed via the least squares fit technique using an equation describing the motion of the respiratory system, which uses primary signs such as airway pressure, tidal volume, air flow, and esophageal pressures. Measurements were taken after tracheal intubation, PnP, NMB, establishment of PEEP (10 cmH2O), and PEEP withdrawal [zero end-expiratory pressure (ZEEP)].

RESULTS

PnP significantly increased E(RS) by 27%; both E(P) and E(CW) increased 21.3 and 64.1%, respectively (P < 0.001). NMB did not alter the respiratory mechanic properties. Setting PEEP reduced E(RS) by 8.6% (P < 0.05), with a reduction of 10.9% in E(P) (P < 0.01) and a significant decline of 15.7% in R(RS) (P < 0.05). These transitory changes in elastance disappeared after ZEEP.

CONCLUSIONS

We concluded that the 10 cmH2O of PEEP attenuates the effects of PnP in respiratory mechanics, lowering R(RS), E(P), and E(RS). These effects may be useful in the ventilatory approach for patients experiencing a non-physiological increase in IAP owing to PnP in laparoscopic procedures.

[Special features of laparoscopic operations from an anesthesiologic viewpoint: a review]

The value of laparoscopic procedures has increased over the last decade. Many patients undergoing laparoscopic surgery also have coexisting diseases. The hemodynamic effects of intraperitoneal carbon dioxide insufflation depend on the extent of intraperitoneal pressure, severity of preexisting cardiopulmonary diseases, volume state of the patient and alterations of acid-base balance due to a capnoperitoneum. In addition to endocrinologic reactions, patient positioning also affects hemodynamic parameters. In high risk patients extended cardiopulmonary monitoring with an arterial line and repeated blood gas analysis is recommended intraoperatively, in addition to assessment of end-expiratory CO(2). In this patient group the intra-abdominal pressure should be maintained in the range of 5-7 mmHg.

Peri-operative anaesthetic management of cytoreductive surgery with hyperthermic intraperitoneal chemotherapy

Cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (HIPEC) is a long and complex procedure with significant blood and fluid loss during debulking and important pathophysiological alterations during the HIPEC phase. We performed a retrospective analysis of 78 consecutive patients undergoing cytoreductive surgery with HIPEC at a university hospital. Our data demonstrate large intra-operative fluid turnover, with 51% of patients requiring a blood transfusion. During HIPEC, airway pressure and central venous pressure increased with a lower oxygenation ratio as a result of increased intra-abdominal pressure with the closed abdomen technique. As a consequence of the raised body temperature, heart rate, end tidal carbon dioxide and arterial lactate levels increased with a slight metabolic acidosis. Peri-operative analysis of routine clotting parameters revealed disturbances of the coagulation status. For pain management, 72% of patients received supplementary thoracic epidural analgesia with consequential peri-operative opioid sparing and a reduced duration of postoperative ventilation.

Laparoscopic cholecystectomy with carbon dioxide pneumoperitoneum is safe even for high-risk patients

BACKGROUND

Because of absorbed carbon dioxide (CO(2)) and elevated intraabdominal pressure (IAP), CO(2) pneumoperitoneum (CO(2)PP) has potentially harmful intraoperative circulatory and ventilatory effects. Although not clinically significant for healthy patients, these effects are assumed to be deleterious for patients with a high risk for anesthesia (American Society of Anesthesiology [ASA] 3 and 4) and significant cardiopulmonary, renal, or hepatic diseases. The authors assessed CO(2)PP-related adverse effects by comparing ASA 3 and 4 patients who underwent laparoscopic cholecystectomy (LC) with or without CO(2)PP.

METHODS

A total of 20 successive ASA 3 and 4 patients who underwent LC were randomized into CO(2)PP (n = 10) and abdominal wall elevator (Laparolift) (n = 10) groups. The parameters for perioperative hemodynamics, ventilation, perfusion of intraabdominal organs, and blood chemistry were recorded periodically from before the induction of the anesthesia until postoperative day 2 and compared between the groups.

RESULTS

Mean age, height, weight, the proportional number of ASA 3 vs ASA 4 patients, the volume of perioperative fluid loading, and the dose of analgesics did not differ significantly between the groups. The length of the operation was 49.9 +/- 10.6 min for the CO(2)PP group and 50.6 +/- 17.2 min for Laparolift group (nonsignificant difference). The mean central venous pressure (CVP) 30 min after insufflation was higher (12.3 +/- 4.8 vs 7.9 +/- 3.7 mmHg) and the (Gastric Mucosal pH) pHi at the end of the operation was lower (7.29 +/- 0.07 vs 7.35 +/- 0.04) in the CO(2)PP group than in the Laparolift group (p < 0.05). Later, CVP and pHi did not differ significantly. Other parameters of hemodynamics including oxygenation, perfusion, and blood chemistry did not differ significantly.

CONCLUSIONS

For LC for patients with an ASA 3 and 4 risk for anesthesia, no significant adverse effects could be attributed to CO(2 )pneumoperitoneum. For high-risk patients, preoperative preparation and active perioperative monitoring are essential for safe anesthesia for LC with or without CO(2)PP.