Changes in intrathoracic blood volume associated with pneumoperitoneum and positioning

Effect of the Duration of Restrictive Fluid Therapy on Acute Kidney Injury in Robot-Assisted Laparoscopic Prostatectomy

BACKGROUND

In robot-assisted laparoscopic prostatectomy (RALP), restrictive fluid therapy (RFT) is often utilized until the vesicourethral anastomosis (console period) is completed. RFT can cause acute kidney injury (AKI). Thus, RFT prolongation in surgeries that utilize the Trendelenburg position and pneumoperitoneum may increase the risk of postoperative AKI. We aimed to evaluate the effect of RFT duration on postoperative AKI.

METHODS

Forty-four patients who underwent RALP were included in this prospective observational study. Patients were divided into two groups according to the RFT duration (Group I, RFT duration ≤ 3 h, and Group II, RFT duration >3 h). AKI was diagnosed and staged according to the Kidney Disease Improving Global Outcomes criteria (KDIGO) using patients' serum creatinine levels after the first 24 h postoperatively. Hemodynamic parameters were monitored using the pressure recording analytical method.

RESULTS

The AKI incidence was significantly higher in Group II than in Group I (45.5% vs. 9.1%; p = 0.016). In both groups, all patients who developed AKI were KDIGO stage 1 and all recovered on the second postoperative day. At the end of the console period, the heart rate and arterial elastance were significantly higher, whereas the stroke volume index was significantly lower in Group II than in Group I (p = 0.041, p = 0.016, and p < 0.001, respectively). Although the amounts of fluid administered before and after the anastomosis were similar between the groups, the total amount of fluid administered was significantly different (p < 0.001). There was a significant negative correlation between RFT duration and the total amount of fluid administered (r2 = 0.43, p < 0.001). RFT duration of >3 h, total fluid administration of ≤3.3 mL/kg/h, and stroke volume index (SVI) at the end of the console period of ≤32 mL/m2 increased the risk of AKI by 12.0 times (1.7-85.2) (p = 0.013).

CONCLUSION

RFT prolongation in RALP may increase the risk of developing AKI.

Femoral Occlusion during Neonatal Cardiopulmonary Resuscitation Improves Outcomes in an Ovine Model of Perinatal Cardiac Arrest

BACKGROUND

The goal of chest compressions during neonatal resuscitation is to increase cerebral and coronary blood flow leading to the return of spontaneous circulation (ROSC). During chest compressions, bilateral femoral occlusion may increase afterload and promote carotid and coronary flow, an effect similar to epinephrine. Our objectives were to determine the impact of bilateral femoral occlusion during chest compressions on the incidence and timing of ROSC and hemodynamics.

METHODOLOGY

In this randomized study, 19 term fetal lambs in cardiac arrest were resuscitated based on the Neonatal Resuscitation Program guidelines and randomized into two groups: femoral occlusion or controls. Bilateral femoral arteries were occluded by applying pressure using two fingers during chest compressions.

RESULTS

Seventy percent (7/10) of the lambs in the femoral occlusion group achieved ROSC in 5 ± 2 min and three lambs (30%) did not receive epinephrine. ROSC was achieved in 44% (4/9) of the controls in 13 ± 6 min and all lambs received epinephrine. The femoral occlusion group had higher diastolic blood pressures, carotid and coronary blood flow.

CONCLUSION

Femoral occlusion resulted in faster and higher incidence of ROSC, most likely due to attaining increased diastolic pressures, coronary and carotid flow. This is a low-tech intervention that can be easily adapted in resource limited settings, with the potential to improve survival and neurodevelopmental outcomes.

The evaluation of cardiac functions in deep Trendelenburg position during robotic-assisted laparoscopic prostatectomy

Objective

This study aimed to demonstrate the reliability of the cardiac cycle efficiency value through its correlation with longitudinal strain by observing the effect of the deep Trendelenburg position.

Design

A prospective, observational study.

Setting

Single center.

Participants

Between May and September 2022, the hemodynamic parameters of 30 patients who underwent robotic assisted laparoscopic prostatectomy under general anesthesia were prospectively evaluated.

Measurements and main results

All invasive cardiac monitoring parameters and longitudinal strain achieved transesophageal echocardiography were recorded in pre-deep Trendelenburg position (T3) and 10th minute of deep Trendelenburg position (T4). Delta values were calculated for the cardiac cycle efficiency and longitudinal strain (values at T4 minus values at T3). The estimated power was calculated as 0.99 in accordance with the cardiac cycle efficiency values at T3 and T4 (effect size: 0.85 standard deviations of the mean difference: 0.22, alpha: 0.05). At T4, heart rate, pulse pressure variation, cardiac cycle efficiency, dP/dt and longitudinal strain were significantly lower than those at T3 (p = 0.009, p < 0.001, p < 0.001, and p < 0.001, respectively). There was a positive correlation between the delta-cardiac cycle efficiency and delta-longitudinal strain (R2 = 0.36, p < 0.001).

Conclusion

Although the absence of significant changes in mean arterial pressure and cardiac index after Trendelenburg position suggests that cardiac workload has not changed, changes in cardiac cycle efficiency and longitudinal strain indicate increased cardiac workload due to increased ventriculo-arterial coupling.

A Pilot Study to Examine the Effect of Passive Straight Leg Raise Performed During Cardiopulmonary Resuscitation on Cerebral Perfusion Measured by Noninvasive Cerebral Oximetry

Passive leg raise (PLR) during cardiopulmonary resuscitation (CPR) is simple and noninvasive maneuver, which can potentially improve patient-related outcomes. Initial CPR guidelines have previously advocated "elevation of the lower extremities to augment artificial circulation during CPR." There is lack of supporting evidence for this recommendation.

DESIGN

This was a double cross-over physiologic efficacy randomized study.

SETTING AND PATIENTS

Study in 10 subjects with in-hospital cardiac arrest for whom CPR was undertaken.

INTERVENTION

Subjects were randomized to receive two cycles of CPR with PLR followed by two cycles of CPR without PLR (Group I) or vice-versa (Group II). Subjects had their foreheads (right and left) fitted with near infrared spectroscopy (NIRS) electrodes (O3 System-Masimo, Masimo corporation Forty Parker, Irvine CA) while undergoing CPR during the study. NIRS readings, a measure of mixed venous, arterial, and capillary blood oxygen saturation, act as a surrogate measure of cerebral blood perfusion during CPR.

MEASUREMENT AND MAIN RESULTS

PLR was randomly used "first" in five of them, whereas it was used "second" in the remaining five subjects. In subjects in whom PLR was performed during first two cycles (Group I), NIRS values were initially significantly greater. The performance of PLR during CPR in Group II attenuated the decline in NIRS readings during CPR.

CONCLUSIONS

PLR during CPR is feasible and leads to augmentation of cerebral blood flow. Furthermore, the expected decline in cerebral blood flow over time during CPR may be attenuated by this maneuver. The clinical significance of these findings will require further investigations.

Effect of pneumoperitoneum and Trendelenburg position on internal carotid artery blood flow measured by ultrasound during robotic prostatectomy

INTRODUCTION

Robotic prostatectomy requires pneumoperitoneum and a steep Trendelenburg position; however, this condition may compromise cerebral blood flow. Here, we evaluated the effect of pneumoperitoneum and the steep Trendelenburg position on internal carotid artery (ICA) blood flow measured by Doppler ultrasound during robotic prostatectomy.

METHODS

Patients who underwent robotic prostatectomy were prospectively recruited. The ICA blood flow was measured at the following five time-points: with the patient awake and in the supine position (Ta), 10 min after anaesthetic induction in the supine position (T1), 10 (T2) and 30 (T3) min after pneumoperitoneum in the steep Trendelenburg position, and at the end of surgery in the supine position after desufflation of the pneumoperitoneum (T4). Hemodynamic and cerebrovascular variables were measured at each time-point.

RESULTS

A total of 28 patients were evaluated. The ICA blood flows were significantly lower at T2 and T3 than at T1 (162.3±44.7 [T2] vs. 188.0±49.6 mL/min [T1], P=0.002; 163.1±39.9 [T3] vs. 188.0±49.6 mL/min [T1], P=0.009). The ICA blood flow also differed significantly between Ta and T1 (236.8±58.3 vs. 188.0±49.6 mL/min, P<0.001). Heart rates, cardiac indexes, peak systolic velocity, and end-diastolic velocity were significantly lower at T2 and T3 than at T1. However, ICA diameter, mean blood pressure, and end-tidal carbon dioxide partial pressure did not differ significantly at all time-points.

CONCLUSION

Pneumoperitoneum and the steep Trendelenburg position caused decreased ICA blood flow, suggesting that they should be carefully performed during robotic prostatectomy, especially in patients at risk of postoperative cerebrovascular accident. This article is protected by copyright. All rights reserved.

Pronounced haemodynamic changes during and after robotic-assisted laparoscopic prostatectomy: a prospective observational study

OBJECTIVES

Robotic-assisted laparoscopic prostatectomy (RALP) is typically conducted in steep Trendelenburg position (STP). This study investigated the influence of permanent 45° STP and capnoperitoneum on haemodynamic parameters during and after RALP.

DESIGN

Prospective observational study.

SETTING

Haemodynamic changes were recorded with transpulmonary thermodilution and pulse contour analysis in men undergoing RALP under standardised anaesthesia.

PARTICIPANTS

Informed consent was obtained from 51 patients scheduled for elective RALP in a University Medical Centre in Germany.

INTERVENTIONS

Heart rate, mean arterial pressure, central venous pressure (CVP), Cardiac Index (CI), systemic vascular resistance (SVR), Global End-Diastolic Volume Index (GEDI), global ejection fraction (GEF), Cardiac Power Index (CPI) and stroke volume variation (SVV) were recorded at six time points: 20 min after induction of anaesthesia (T1), after insufflation of capnoperitoneum in supine position (T2), after 30 min in STP (T3), when controlling Santorini's plexus in STP (T4), before awakening in supine position (T5) and after 45 min in the recovery room (T6). Adverse cardiac events were registered intraoperatively and postoperatively.

RESULTS

All haemodynamic parameters were significantly changed by capnoperitoneum and STP during RALP and partly normalised at T6. CI, GEF and CPI were highest at T6 (CI: 3.9 vs 2.2 L/min/m²; GEF: 26 vs 22%; CPI: 0.80 vs 0.39 W/m²; p<0.001). CVP was highest at T4 (31 vs 7 mm Hg, p<0.001) and GEDI at T6 (819 vs 724 mL/m², p=0.005). Mean SVR initially increased (T2) but had decreased by 24% at T6 (p<0.001). SVV was highest at T5 (12 vs 9%, p<0.001). Two of the patients developed cardiac arrhythmia during RALP and one patient suffered postoperative cardiac ischaemia.

CONCLUSIONS

RALP led to pronounced perioperative haemodynamic changes. The combination of increased cardiac contractility and heart rate reflects a hyperdynamic situation during and after RALP. Anaesthesiologists should be aware of unnoticed pre-existing heart failure to worsen during STP in patients undergoing RALP.

Comparison of volume-controlled, pressure-controlled, and pressure-controlled volume-guaranteed ventilation during robot-assisted laparoscopic gynecologic surgery in the Trendelenburg position

Background: Pressure-controlled ventilation volume-guaranteed (PCV-VG) is being increasingly used for ventilation during general anesthesia. Carbon dioxide (CO₂) pneumoperitoneum in the Trendelenburg position is routinely used during robot-assisted laparoscopic gynecologic surgery. Here, we hypothesized that PCV-VG would reduce peak inspiratory pressure (Ppeak), compared to volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV). Methods: In total, 60 patients were enrolled in this study and randomly assigned to receive VCV, PCV, or PCV-VG. Hemodynamic variables, respiratory variables, and arterial blood gases were measured in the supine position 15 minutes after the induction of anesthesia (T0), 30 and 60 minutes after CO₂ pneumoperitoneum and Trendelenburg positioning (T1 and T2, respectively), and 15 minutes after placement in the supine position at the end of anesthesia (T3). Results: The Ppeak was higher in the VCV group than in the PCV and PCV-VG groups (p=0.011). Mean inspiratory pressure (Pmean) was higher in the PCV and PCV-VG groups than in the VCV group (p<0.001). Dynamic lung compliance (Cdyn) was lower in the VCV group than in the PCV and PCV-VG groups (p=0.001). Conclusion: Compared to VCV, PCV and PCV-VG provided lower Ppeak, higher Pmean, and improved Cdyn, without significant differences in hemodynamic variables or arterial blood gas results during robot-assisted laparoscopic gynecologic surgery with Trendelenburg position.

Effect of Systolic Cardiac Function on Passive Leg Raising for Predicting Fluid Responsiveness: A Prospective Observational Study

BACKGROUND

Passive leg raising (PLR) represents a "self-volume expansion (VE)" that could predict fluid responsiveness, but the influence of systolic cardiac function on PLR has seldom been reported. This study aimed to investigate whether systolic cardiac function, estimated by the global ejection fraction (GEF) from transpulmonary-thermodilution, could influence the diagnostic value of PLR.

METHODS

This prospective, observational study was carried out in the surgical Intensive Care Unit of the First Affiliated Hospital of Sun Yat-sen University from December 2013 to July 2015. Seventy-eight mechanically ventilated patients considered for VE were prospectively included and divided into a low-GEF (<20%) and a near-normal-GEF (≥20%) group. Within each group, baseline hemodynamics, after PLR and after VE (250 ml 5% albumin over 30 min), were recorded. PLR-induced hemodynamic changes (PLR-Δ) were calculated. Fluid responders were defined by a 15% increase of stroke volume (SV) after VE.

RESULTS

Twenty-five out of 38 patients were responders in the GEF <20% group, compared to 26 out of 40 patients in the GEF ≥20% group. The thresholds of PLR-ΔSV and PLR-Δ cardiac output (PLR-ΔCO) for predicting fluid responsiveness were higher in the GEF ≥20% group than in the GEF <20% group (ΔSV: 12% vs. 8%; ΔCO: 7% vs. 6%), with increased sensitivity (ΔSV: 92% vs. 92%; ΔCO: 81% vs. 80%) and specificity (ΔSV: 86% vs. 70%; ΔCO: 86% vs. 77%), respectively. PLR-Δ heart rate could predict fluid responsiveness in the GEF ≥20% group with a threshold value of -5% (sensitivity 65%, specificity 93%) but could not in the GEF <20% group. The pressure index changes were poor predictors.

CONCLUSIONS

In the critically ill patients on mechanical ventilation, the diagnostic value of PLR for predicting fluid responsiveness depends on cardiac systolic function. Thus, cardiac systolic function must be considered when using PLR.

TRIAL REGISTRATION

Chinese Clinical Trial Register, ChiCTR-OCH-13004027; http://www.chictr.org.cn/showproj.aspx?proj=5540.

Intraocular Pressure Changes during Laparoscopic Surgery in Trendelenburg Position in Patients Anesthetized with Propofol-based Total Intravenous Anesthesia Compared to Sevoflurane Anesthesia: A Comparative Study

Background:

Intraocular pressure (IOP) is increased during laparoscopic surgery with Trendelenburg position and may contribute to deleterious effects on optic nerve in susceptible patients.

Aims:

The primary objective of this study is to compare the effects of propofol-based total intravenous anesthesia (TIVA) with those of sevoflurane anesthesia on IOP in patients undergoing lower abdominal laparoscopic surgery in Trendelenburg position. Secondary objectives are to compare hemodynamic changes, mean arterial pressure (MAP), end-tidal CO₂, and peak inspiratory pressure changes.

Materials and Methods:

Sixty patients with physical status American Society of Anesthesiologists classes I and II were randomly allocated in two groups: Group A (propofol) and Group B (sevoflurane). IOP along with other parameters was measured at seven points including baseline (T0), 5 min after induction (T1), 5 min after CO₂ pneumoperitoneum in supine position (T2), 30 min after CO₂ pneumoperitoneum with Trendelenburg position (T3), 5 min after returning to supine position (T4), 5 min after CO₂ desufflation (T5), and 5 min after extubation (T6).

Results:

The change in IOP was different between the two groups. Maximum rise in IOP was seen at T3, and mean ± standard deviation IOP was 15.5 ± 0.9 mmHg and 19.8 ± 1.2 mmHg in Group A and Group B, respectively (P < 0.01). In Group A (propofol), IOP remained almost equal to the baseline value at T3 and the IOP difference was 0.3 ± 0.9 mmHg less than baseline (statistically insignificant, P > 0.05), while in Group B (sevoflurane), IOP increased significantly at T3 and the difference was 4.0 ± 1.2 mmHg (P < 0.001). The IOP was significantly greater (P < 0.01) from T2 to T6 in sevoflurane group than propofol group.

Conclusion:

Propofol-based TIVA is more effective than inhalational anesthesia with sevoflurane in attenuating the increase in IOP during laparoscopic surgery requiring CO₂ pneumoperitoneum with Trendelenburg position.

What is the evidence for the use of low-pressure pneumoperitoneum? A systematic review

Background

Laparoscopic surgery has several advantages when compared to open surgery, including faster postoperative recovery and lower pain scores. However, for laparoscopy, a pneumoperitoneum is required to create workspace between the abdominal wall and intraabdominal organs. Increased intraabdominal pressure may also have negative implications on cardiovascular, pulmonary, and intraabdominal organ functionings. To overcome these negative consequences, several trials have been performed comparing low- versus standard-pressure pneumoperitoneum.

Methods

A systematic review of all randomized controlled clinical trials and observational studies comparing low- versus standard-pressure pneumoperitoneum.

Results and conclusions

Quality assessment showed that the overall quality of evidence was moderate to low. Postoperative pain scores were reduced by the use of low-pressure pneumoperitoneum. With appropriate perioperative measures, the use of low-pressure pneumoperitoneum does not seem to have clinical advantages as compared to standard pressure on cardiac and pulmonary function. Although there are indications that low-pressure pneumoperitoneum is associated with less liver and kidney injury when compared to standard-pressure pneumoperitoneum, this does not seem to have clinical implications for healthy individuals. The influence of low-pressure pneumoperitoneum on adhesion formation, anastomosis healing, tumor metastasis, intraocular and intracerebral pressure, and thromboembolic complications remains uncertain, as no human clinical trials have been performed. The influence of pressure on surgical conditions and safety has not been established to date. In conclusion, the most important benefit of low-pressure pneumoperitoneum is lower postoperative pain scores, supported by a moderate quality of evidence. However, the quality of surgical conditions and safety of the use of low-pressure pneumoperitoneum need to be established, as are the values and preferences of physicians and patients regarding the potential benefits and risks. Therefore, the recommendation to use low-pressure pneumoperitoneum during laparoscopy is weak, and more studies are required.

Cardiac and hemodynamic consequences during capnoperitoneum and steep Trendelenburg positioning: lessons learned from robot-assisted laparoscopic prostatectomy

STUDY OBJECTIVE

To determine and interpret the changes in preload, afterload, and cardiac function in the different phases of robot-assisted laparoscopic prostatectomy.

DESIGN

Prospective, observational monocenter study.

SETTING

Operating room at a university hospital.

PATIENTS

31 consecutive, ASA physical status 1, 2, and 3 patients.

INTERVENTIONS

Observations were made at 5 distinct time points: baseline after induction of anesthesia, after initiation of capnoperitoneum, immediately after a 45° head-down tilt, 15 minutes after the 45° head-down tilt was established, after the release of the capnoperitoneum, and 5 minutes after the patient was returned to a horizontal position (end).

MEASUREMENTS

Transpulmonary thermodilution and pulse contour analysis were used to record hemodynamic changes in preload, afterload, and cardiac function.

MAIN RESULTS

While central venous pressure increased threefold from baseline, none of the other preload parameters showed excessive fluid overload or demand. There was no significant change in cardiac contractility over time. Afterload increased significantly during the capnoperitoneum and significantly decreased compared with baseline after the release of abdominal pressure at the end of the procedure. Heart rate and cardiac index increased significantly during robot-assisted laparoscopic prostatectomy.

CONCLUSIONS

Selective arterial vasodilation at the time of capnoperitoneum may normalize afterload and myocardial oxygen demand.

Passive leg raise (PLR) during cardiopulmonary (CPR) - a method article on a randomised study of survival in out-of-hospital cardiac arrest (OHCA)

BACKGROUND

It is estimated that about 275,000 inhabitants experience an out-of-hospital cardiac arrest (OHCA) every year in Europe. Survival in out-of-hospital cardiac arrest is relatively low, generally between five per cent and 10%. Being able to explore new methods to improve the relatively low survival rate is vital for people with these conditions. Passive leg raise (PLR) during cardiopulmonary resuscitation (CPR) has been found to improve cardiac preload and blood flow during chest compressions. The aim of our study is to evaluate whether early PLR during CPR also has an impact on one-month survival in sudden and unexpected out-of-hospital cardiac arrest (OHCA).

METHOD/DESIGN

A prospective, randomized, controlled trial in which all patients (≥18 years) receiving out-of hospital CPR are randomized by envelope to be treated with either PLR or in the flat position. The ambulance crew use a special folding stool which allows the legs to be elevated about 20 degrees. Primary end-point: survival to one month. Secondary end-point: survival to hospital admission to one month and to one year with acceptable cerebral performance classification (CPC) 1-2.

DISCUSSION

PLR is a simple and fast maneuver. We believe that the greatest benefit with PLR is when performed early in the process, during the first minutes of CPR and before the first defibrillation. To reach power this study need 3000 patients, we hope that this method article will encourage other sites to contact us and take part in our study.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01952197.

Cardiac ultrasound and abdominal compartment syndrome

This review focuses on the available literature published about the evaluation of haemodynamic consequences of the abdominal compartment syndrome (ACS). Animal and clinical studies described decreased venous return, systemic vasoconstriction, systolic and diastolic dysfunction of left and right ventricles. Doppler echocardiography is a non-invasive bedside procedure which provides a complete haemodynamic evaluation of patients with ACS. Despite numerous evaluations in anesthesia during laparoscopic surgery, the use of echocardiography remains scarce in critically ill patients with ACS.

Anaesthesia for laparoscopic kidney transplantation: Influence of Trendelenburg position and CO2 pneumoperitoneum on cardiovascular, respiratory and renal function

Background:

Laparoscopic donor nephrectomy is a routine practice since 1995. Until now, the recipient has always undergone open surgery for transplantation. In our institute, laparoscopic kidney transplantation (LKT) started in 2010. To facilitate this surgery, the patient must be in steep Trendelenburg position for a long duration. Hence, we decided to study the effect of CO2 pnuemoperitoneum and Trendelenburg position in chronic renal failure (CRF) patients undergoing LKT.

Methods:

A total of 20 adult CRF patients having mean age of 31.7±10.36 years and body mass index 19.65±3.41 kg/m² without significant coronary artery disease were selected for the procedure. Cardiovascular parameters heart rate (HR), mean arterial pressure (MAP), Central venous pressure (CVP) and respiratory parameters (ETCO₂, peak airway pressure) were noted at the time of induction, after induction, 15 min after creation of pnuemoperitoneum, 30 min after Trendelenburg position, 15 min after decompression of pnuemoperitonuem and after extubation. Arterial blood gas analysis was carried out after induction, 15 min after creation of pnuemoperitoneum, 30 min after Trendelenburg position and 15 min after clamp release. Total duration of surgery, anastomosis time, time for the establishment of urine output and total urine output were noted. Serum creatinine on the 1^st and 7^th post-operative day were recorded.

Results:

Significant increase in HR was observed after creation of CO₂ pneumoperitoneum and just before extubation. Significant increase in the MAP and CVP was noted after creation of pneumoperitoneum and after giving Trendelenburg position. No significant rise in the ETCO₂ and PaCO₂ was observed. Significant increase in the base deficit was observed after the clamp release, but none of the patients required correction.

Conclusion:

LKT performed in steep Trendelenburg position with CO₂ pneumoperitoneum significantly influenced cardiovascular and respiratory homeostasis; however, measured parameters remained within clinically acceptable range without affecting early function of the transplanted kidney.

Effects of different tidal volumes in pulmonary and extrapulmonary lung injury with or without intraabdominal hypertension

PURPOSE

We hypothesized that: (1) intraabdominal hypertension increases pulmonary inflammatory and fibrogenic responses in acute lung injury (ALI); (2) in the presence of intraabdominal hypertension, higher tidal volume reduces lung damage in extrapulmonary ALI, but not in pulmonary ALI.

METHODS

Wistar rats were randomly allocated to receive Escherichia coli lipopolysaccharide intratracheally (pulmonary ALI) or intraperitoneally (extrapulmonary ALI). After 24 h, animals were randomized into subgroups without or with intraabdominal hypertension (15 mmHg) and ventilated with positive end expiratory pressure = 5 cmH(2)O and tidal volume of 6 or 10 ml/kg during 1 h. Lung and chest wall mechanics, arterial blood gases, lung and distal organ histology, and interleukin (IL)-1β, IL-6, caspase-3 and type III procollagen (PCIII) mRNA expressions in lung tissue were analyzed.

RESULTS

With intraabdominal hypertension, (1) chest-wall static elastance increased, and PCIII, IL-1β, IL-6, and caspase-3 expressions were more pronounced than in animals with normal intraabdominal pressure in both ALI groups; (2) in extrapulmonary ALI, higher tidal volume was associated with decreased atelectasis, and lower IL-6 and caspase-3 expressions; (3) in pulmonary ALI, higher tidal volume led to higher IL-6 expression; and (4) in pulmonary ALI, liver, kidney, and villi cell apoptosis was increased, but not affected by tidal volume.

CONCLUSIONS

Intraabdominal hypertension increased inflammation and fibrogenesis in the lung independent of ALI etiology. In extrapulmonary ALI associated with intraabdominal hypertension, higher tidal volume improved lung morphometry with lower inflammation in lung tissue. Conversely, in pulmonary ALI associated with intraabdominal hypertension, higher tidal volume increased IL-6 expression.

The effect of nitroglycerin on hemodynamic changes during laparoscopic low anterior resection

BACKGROUND

More laparoscopic low anterior resections (LAR) are being performed in recent years. There has been controversy around the hemodynamic changes affected by the Trendelenburg position and pneumoperitoneum during LAR. The goal of this study was to analyze the effect of nitroglycerin (NTG) on hemodynamic changes during LAR.

METHODS

Forty ASA physical status I-II patients undergoing LAR were randomized into two groups: the NTG infused group (N group, n = 20) and the control group (C group, n = 20). Anesthesia was maintained with sevoflurane at 1-3 vol%, air/oxygen (50%/50%) and continuous infusion with remifentanil. The N group patients were given 0.5 µg/kg/min of NTG during anesthesia. Mean arterial pressure (MAP), heart rate (HR), central venous pressure (CVP), cardiac index (CI), stroke volume (SV) and systemic vascular resistance (SVR) were assessed 10 min after induction (T1), 5 min after pneumoperitoneum in the supine position (T2), 10 min after pneumoperitoneum in the Trendelenburg position (T3), 30 min after pneumoperitoneum in the Trendelenburg position (T4), 1 hr after pneumoperitoneum in the Trendelenburg position (T5) in addition to 5 (T6), 10 (T7) and 30 min (T8) after removal of the pneumoperitoneum in the supine position.

RESULTS

The increases of MAP were milder in the N group (22.6-7.3%) than the C group (32.3-17.7%) during pneumoperitoneum and while in the Trendelenburg position. The significant decreases of HR were maintained in the C group, but the changes in HR were not significant in N group during the operation. The increases in CVP were less in N group than C group. The increases of SVR were milder in N group (19.4-1.4%) than C group (41.7-16.6%) during pneumoperitoneum in the Trendelenburg position.

CONCLUSIONS

Intraoperative NTG infusions were effective to some degree in reducing the hemodynamic changes during pneumoperitoneum with Trendelenburg positioning for LAR.

Peripheral venous pressure as an alternative to central venous pressure in patients undergoing laparoscopic colorectal surgery

BACKGROUND

Peripheral venous pressure (PVP) is strongly correlated with central venous pressure (CVP) during various surgeries. Laparoscopic surgery in the Trendelenburg position with pneumoperitoneum typically increases CVP. To determine whether PVP convincingly reflects changes in CVP, we evaluated the correlation between PVP and CVP in patients undergoing laparoscopic colorectal surgery.

METHODS

Both CVP and PVP were measured simultaneously at predetermined time intervals during elective laparoscopic colorectal surgery in 42 patients without cardiac disease. The pairs of venous pressure measurements were analysed for correlation, and the Bland-Altman plots of repeated measures were used to evaluate the agreement between CVP and PVP.

RESULTS

A total of 420 data pairs were obtained. The overall mean CVP was 11.3 (sd 4.5) mm Hg, which was significantly lower than the measured PVP of mean 12.1 (4.5) mm Hg (P=0.005). There was a strong positive correlation between overall CVP and PVP (correlation coefficient=0.96, P<0.0001). The mean bias (PVP-CVP) corrected for repeated measurements using random-effects modelling was 0.9 mm Hg [95% confidence interval (CI) 0.54-1.19 mm Hg] with 95% limits of agreement of -1.2 mm Hg (95% CI -1.75 to -0.62 mm Hg) to 2.9 mm Hg (95% CI 2.35-3.48 mm Hg).

CONCLUSIONS

PVP displays a strong correlation and agreement with CVP under the increased intrathoracic pressure of pneumoperitoneum in the Trendelenburg position and may be used as an alternative to CVP in patients without cardiac disease undergoing laparoscopic colorectal surgery.

Transcutaneous carbon dioxide monitoring accurately predicts arterial carbon dioxide partial pressure in patients undergoing prolonged laparoscopic surgery

BACKGROUND

There may be large differences between measurements of end-tidal carbon dioxide partial pressure (Petco(2)) and arterial carbon dioxide partial pressure (Paco(2)) during laparoscopic surgeries. Transcutaneous carbon dioxide (Ptcco(2)) monitoring can be used to noninvasively and continuously estimate Paco(2). In the present study we evaluated the accuracy of Ptcco(2) monitoring in predicting the Paco(2) during laparoscopic surgeries with prolonged pneumoperitoneum.

METHODS

Sixteen patients who underwent laparoscopic radical gastrectomy or radical proctectomy under general anesthesia were included in the study. Their Paco(2), Petco(2), and Ptcco(2) values were measured at 3 time points before and after pneumoperitoneum. Agreement among measures was assessed by the Bland-Altman method.

RESULTS

Forty-eight sample sets were obtained. The average Paco(2)- Ptcco(2) difference was -0.9 + or - 6.4 mm Hg (mean + or - 2 SD). The average Paco(2) - Petco(2) difference was 7.5 + or - 7.0 mm Hg (mean + or - 2 SD). Paco(2) - Ptcco(2) was less than or equal to + or -5 mm Hg for 88% of the samples. Paco(2) - Petco(2) was less than or equal to + or -5 mm Hg for 17% of the samples (P < 0.05).

CONCLUSIONS

While undergoing long-term pneumoperitoneum laparoscopic surgery, Ptcco(2) monitoring is more accurate than is PETCO(2) monitoring in predicting the patients' Paco(2).

Passive leg raising is predictive of fluid responsiveness in spontaneously breathing patients with severe sepsis or acute pancreatitis

OBJECTIVE

Rapid fluid loading is standard treatment for hypovolemia. Because volume expansion does not always improve hemodynamic status, predictive parameters of fluid responsiveness are needed. Passive leg raising is a reversible maneuver that mimics rapid volume expansion. Passive leg raising-induced changes in stroke volume and its surrogates are reliable predictive indices of volume expansion responsiveness for mechanically ventilated patients. We hypothesized that the hemodynamic response to passive leg raising indicates fluid responsiveness in nonintubated patients without mechanical ventilation.

DESIGN

Prospective study.

SETTING

Intensive care unit of a general hospital.

PATIENTS

We investigated consecutive nonintubated patients, without mechanical ventilation, considered for volume expansion.

INTERVENTIONS

We assessed hemodynamic status at baseline, after passive leg raising, and after volume expansion (500 mL 6% hydroxyethyl starch infusion over 30 mins).

MEASUREMENTS AND MAIN RESULTS

We measured stroke volume using transthoracic echocardiography, radial pulse pressure using an arterial catheter, and peak velocity of femoral artery flow using continuous Doppler. We calculated changes in stroke volume, pulse pressure, and velocity of femoral artery flow induced by passive leg raising (respectively, Deltastroke volume, Deltapulse pressure, and Deltavelocity of femoral artery flow). Among 34 patients included in this study, 14 had a stroke volume increase of >or=15% after volume expansion (responders). All patients included in the study had severe sepsis (n = 28; 82%) or acute pancreatitis (n = 6; 18%). The Deltastroke volume >or=10% predicted fluid responsiveness with sensitivity of 86% and specificity of 90%. The Deltapulse pressure >or=9% predicted fluid responsiveness with sensitivity of 79% and specificity of 85%. The Deltavelocity of femoral artery flow >or=8% predicted fluid responsiveness with sensitivity of 86% and specificity of 80%.

CONCLUSIONS

Changes in stroke volume, radial pulse pressure, and peak velocity of femoral artery flow induced by passive leg raising are accurate and interchangeable indices for predicting fluid responsiveness in nonintubated patients with severe sepsis or acute pancreatitis.

Abdominal compression increases upper airway collapsibility during sleep in obese male obstructive sleep apnea patients

STUDY OBJECTIVES

Abdominal obesity, particularly common in centrally obese males, may have a negative impact on upper airway (UA) function during sleep. For example, cranial displacement of the diaphragm with raised intra-abdominal pressure may reduce axial tension exerted on the UA by intrathoracic structures and increase UA collapsibility during sleep.

DESIGN

This study aimed to examine the effect of abdominal compression on UA function during sleep in obese male obstructive sleep apnea patients.

SETTING

Participants slept in a sound-insulated room with physiologic measurements controlled from an adjacent room.

PARTICIPANTS

Fifteen obese (body mass index: 34.5 +/- 1.1 kg/m2) male obstructive sleep apnea patients (apnea-hypopnea index: 58.1 +/- 6.8 events/h) aged 50 +/- 2.6 years participated.

INTERVENTIONS

Gastric (PGA) and transdiaphragmatic pressures (P(DI)), UA closing pressure (UACP), UA airflow resistance (R(UA)), and changes in end-expiratory lung volume (EELV) were determined during stable stage 2 sleep with and without abdominal compression, achieved via inflation of a pneumatic cuff placed around the abdomen. UACP was assessed during brief mask occlusions.

MEASUREMENTS AND RESULTS

Abdominal compression significantly decreased EELV by 0.53 +/- 0.24 L (P=0.045) and increased PGA (16.2 +/- 0.8 versus 10.8 +/- 0.7 cm H2O, P < 0.001), P(DI) (11.7 +/- 0.9 versus 7.6 +/- 1.2 cm H2O, P < 0.001) and UACP (1.4 +/- 0.8 versus 0.9 +/- 0.9 cm H2O, P = 0.039) but not R(UA)(6.5 +/- 1.4 versus 6.9 +/- 1.4 cm H2O x L/s, P=0.585).

CONCLUSIONS

Abdominal compression negatively impacts on UA collapsibility during sleep and this effect may help explain strong associations between central obesity and obstructive sleep apnea.

Early postnatal behavioral changes in the Mecp2-308 truncation mouse model of Rett syndrome

In a mouse model of Rett syndrome (RTT) which expresses a truncated form of methyl-CpG-binding protein 2 (Mecp2) gene (Mecp2-308), we performed a neurobehavioral evaluation across the life span, starting from soon after birth till adulthood. A focus was made on those developmental phases and behavioral domains which have not been previously investigated. The results evidenced subtle anomalies on postnatal days (pnds) 3 to 9 (so-called presymptomatic phase) in spontaneous movements by hemizygous neonatal male mice. Specifically as early as pnd 3, mutant pups exhibited more intense curling and more side responses and on pnd 9 more pivoting and head rising behaviors than wild type (wt) littermates. A significant decrease in ultrasonic vocalization rate, also emerged in Mecp2-308 pups. The same mice were also characterized by increased anxiety-like behaviors (open-field and zero-maze tests) during the early symptomatic phase, in the absence of changes in cognitive passive-avoidance task and rotarod performances. Upon the clearly symptomatic stage, 5-month-old Mecp2-308 mice were also associated with reduced spontaneous home-cage motor activity, motor coordination impairments (rotarod and dowel tests), and a more marked profile of D-amphetamine (10 mg/kg) released stereotyped behavioral syndrome than wt mice. Present results provide an interesting timeline of the progression of symptoms in the Mecp2-308 model and emphasize the need for increased attention to the presymptomatic phase which may be especially informative in mouse models of human neurodevelopmental disorders. This analysis has provided evidence of precocious behavioral markers of RTT and has identified an early developmental window of opportunities on which potential therapies could be investigated.

[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.

How to measure and interpret volumetric measures of preload

PURPOSE OF REVIEW

To update the situation over the past few years on the clinical application of volumetric measures of preload in critically ill patients.

RECENT FINDINGS

Cardiac filling pressures monitoring is unreliable for assessing cardiac preload in mechanically ventilated critically ill patients. The transpulmonary dilution indicator technique was shown to better identify preload than pulmonary arterial catheterization. Measuring static preload index as intrathoracic blood volume or global end diastolic volume provides a good preload index, either in experimental or in different clinical settings.

SUMMARY

Volumetric measures of preload are good preload indexes. These data are to be interpreted together with the clinical patient's condition, conventional hemodynamic data and the course of illness in critically ill patients. In order to evaluate whether the application of a predefined therapy algorithm based on volumetric monitoring can improve patients' outcome, more studies are needed.

Physiological responses to endoscopic surgery in children

The knowledge on the physiological impact of endoscopic surgery in infants and children is limited. Cardiovascular effects of pneumoperitoneum are mainly the result of an increase in intraabdominal pressure, absorption of carbon dioxide, and a stimulation of the neurohumoral vasoactive system. In infants, pneumoperitoneum alters the heart rate, mean arterial pressure, left ventricular endsystolic and end-diastolic volume, and meridional wall stress. Urine production is significantly reduced, and cerebral oxygenation and blood flow are altered. However, postoperative immune function is preserved or restored faster, and specific physiological responses to endoscopic surgery are well tolerated by otherwise healthy infants and children. The effects in children with specific conditions, such as sepsis, cancer, or organ dysfunction, remain to be investigated.

Forehead reflectance oximetry: a clinical comparison with conventional digit sensors during laparotomic and laparoscopic abdominal surgery

OBJECTIVE

This study compared the performance of forehead reflectance and conventional pulse oximetry (SpO(2)) in mechanically ventilated, anesthetized patients undergoing major abdominal surgery with either laparoscopic or laparotomic techniques.

METHODS

SpO(2) was continuously measured both with a forehead reflectance and a conventional digit sensor in 20 ASA physical status I-III, anesthetized patients undergoing either a laparotomic (group Laparotomy, n = 10) or laparoscopic (group Laparoscopy, n = 10) major abdominal surgery. SpO(2) values measured with the two sensors were continuously recorded at 10-second intervals during the entire procedure, and then analyzed for consistency.

RESULTS

In group Laparotomy finger and forehead readings remained consistently similar during the study period; on the contrary, in group Laparoscopy forehead SpO(2) readings showed a much wider variability. The mean (95% Confidence Intervals) difference between finger and forehead SpO(2) readings was 2.0% (-1.3% to +6.0%) in group Laparotomy and 2.5% (-3.5% to +8.4%) in group Laparoscopy (p = 0.001); however, in group Laparoscopy the mean difference between digit and forehead SpO(2) values increased from 0.2% (CI(95): -2.1% to +2.5%) during the first hour to 4.5% (CI(95): -2.5% to +11-5%) in the second hour (p = 0.0005), and 3.1% (CI(95): -2.4% to + 8.6%) in the third hour of surgery (p = 0.0005). Clinically relevant desaturation (decrease of SpO(2) < 89% for > or =30 s) detected with the forehead sensor in the Laparoscopy group was significantly more frequent and longer lasting than with conventional digit sensor. No differences were observed in group Laparotomy.

CONCLUSIONS

Forehead reflectance oximetry is as accurate as conventional digit based oximetry in mechanically ventilated patients undergoing laparotomic surgery in the supine position, but is significantly influenced by patient positioning and pneumoperitoneum during laparoscopic surgery.

Stroke volume equation for impedance cardiography

The study's goal was to determine if cardiac output (CO), obtained by impedance cardiography (ICG), would be improved by a new equation N, implementing a square root transformation for dZ/dtmax/Z0, and a variable magnitude, mass-based volume conductor Vc. Pulmonary artery catheterisation was performed on 106 cardiac surgery patients pre-operatively. Post-operatively, thermodilution cardiac output (TDCO) was simultaneously compared with ICG CO. dZ/dtmax/Z0 and Z0 were obtained from a proprietary bioimpedance device. The impedance variables, in addition to left ventricular ejection time TLVE and patient height and weight, were input using four stroke volume (SV) equations: Kubicek (K), Sramek (S), Sramek-Bernstein (SB), and a new equation N. CO was calculated as SV x heart rate. Data are presented as mean +/- SD. One way repeated measures of ANOVA followed by the Tukey test were used for inter-group comparisons. Bland-Altman methods were used to assess bias, precision and limits of agreement. P< 0.05 was considered statistically significant. CO implementing N (6.06 +/- 1.48 l min(-1)) was not different from TDCO (5.97 +/- 1.41 l min(-1)). By contrast, CO calculated using K (3.70 +/- 1.53 l min(-1)), S (4.16 +/- 1.83 l min(-1)) and SB (4.37 +/- 1.82 l min(-1)) was significantly less than TDCO. Bland-Altman analysis showed poor agreement between TDCO and K, S and SB, but not between TDCO and N. Compared with TDCO, equation N, using a square-root transformation for dZ/dtmax/Z0, and a mass-based Vc, was superior to existing transthoracic impedance techniques for SV and CO determination.

Effects of continuous negative extra-abdominal pressure on cardiorespiratory function during abdominal hypertension: an experimental study

OBJECTIVE

To investigate whether negative extra-abdominal pressure (NEXAP) improves respiratory function and induces a blood shift from the intrathoracic compartment and to assess whether these effects are influenced by abdominal pressure.

DESIGN AND SETTING

Prospective, randomized, controlled trial in the animal laboratory of a university hospital.

SUBJECTS

Eight sedated and paralyzed pigs (19.6+/-3.4 kg).

INTERVENTIONS

Application of NEXAP (-20 cmH(2)O).

MEASUREMENTS AND RESULTS

Airway, esophageal, gastric and central venous pressures were recorded simultaneously. Intrathoracic blood volume was assessed by PiCCO. The effects of NEXAP were assessed with and without abdominal hypertension by intraperitoneal insufflation of helium. NEXAP caused a lasting drop of gastric (1.97+/-2.26 mmHg) and esophageal (1.21+/-0.67 mmHg) pressures, while end-expiratory airway pressure was similar, hence transpulmonary pressure increased. Intrathoracic blood volume dropped from 358+/-47 to 314+/-47 ml. The fall was associated with a decrease in central venous pressure (R(2)=0.820). When peritoneal pressure was raised (24.7+/-5.5 mmHg), the effects were less marked. However, the difference between negative pressure around the abdomen and the pressure inside the abdomen (effective NEXAP) was correlated with the proportional changes in intrathoracic blood volume (R(2)=0.648), being greater with more negative effective NEXAP. NEXAP improved chest wall elastance during abdominal hypertension (from 0.067+/-0.023 to 0.056+/-0.021 cmH(2)O/ml).

CONCLUSIONS

NEXAP increases lung volume and causes a shift of blood from the intrathoracic compartment. It needs to be tailored against abdominal pressure to be effective.

Intra-abdominal hypertension and the abdominal compartment syndrome

BACKGROUND

Abdominal compartment syndrome (ACS) occurs when intra-abdominal pressure is abnormally high in association with organ dysfunction. It tends to have a poor outcome, even when treated promptly by abdominal decompression.

METHODS

A search of the Medline database was performed to identify articles related to intra-abdominal hypertension and ACS.

RESULTS

Currently there is no agreed definition or management of ACS. However, it is suggested that intra-abdominal pressure should be measured in patients at risk, with values above 20 mmHg being considered abnormal in most. Abdominal decompression should be considered in patients with rising pressure and organ dysfunction, indicated by increased airway pressure, reduced cardiac output and oliguria. Organ dysfunction often occurs at an intra-abdominal pressure greater than 35 mmHg and may start to develop between 26 and 35 mmHg. The mean survival rate of patients affected by compartment syndrome is 53 per cent.

CONCLUSION

The optimal time for intervention is not known, but outcome is often poor, even after decompression. Most of the available information relates to victims of trauma rather than general surgical patients.

An increase of abdominal pressure increases pulmonary edema in oleic acid-induced lung injury

Increased abdominal pressure is common in intensive care unit patients. To investigate its impact on respiration and hemodynamics we applied intraabdominal pressure (aIAP) of 0 and 20 cm H(2)O (pneumoperitoneum) in seven pigs. The whole-lung computed tomography scan and a complete set of respiratory and hemodynamics variables were recorded both in healthy lung and after oleic acid (OA) injury. In healthy lung, aIAP 20 cm H(2)O significantly lowered the gas content, leaving the tissue content unchanged. In OA-injured lung at aIAP 0 cm H(2)O, the gas content significantly decreased compared with healthy lung. The excess tissue mass (edema) amounted to 30 +/- 24% of the original tissue weight (455 +/- 80 g). The edema was primarily distributed in the base regions and was not gravity dependent. Heart volume, central venous, pulmonary artery, wedge, and systemic arterial pressures significantly increased. At aIAP 20 cm H(2)O in OA-injured lung, the central venous and pulmonary artery pressures further increased. The gas content further decreased, and the excess tissue mass rose up to 103 +/- 37% (tissue weight 905 +/- 134 g), with homogeneous distribution along the cephalocaudal and sternovertebral axis. We conclude that in OA-injured lung, the increase of IAP increases the amount of edema.

Intraocular pressure changes during laparoscopy in patients anesthetized with propofol total intravenous anesthesia versus isoflurane inhaled anesthesia

We examined intraocular pressure (IOP) changes during gynecologic laparoscopy performed under either thiopental-isoflurane anesthesia or total IV propofol anesthesia. Forty adult women with no preexisting eye disease scheduled for gynecologic CO(2) insufflation laparoscopy were included in the study. Heart rate, mean arterial blood pressure, peak and plateau airway pressure, ETCO(2), and IOP (using a Schioetz tonometer) were measured at defined intervals during the procedure. IOP decreased significantly after the induction of anesthesia in both groups, and remained so throughout the procedure in the propofol group. In the isoflurane group, however, IOP was increased significantly above the preinduction level after pneumoperitoneum with head-down position. There was no correlation between IOP and blood pressure or airway pressure. In conclusion, propofol total IV anesthesia may be a better choice for laparoscopic surgery should control of IOP be a concern.

IMPLICATIONS

In this study, we examined the effect of two anesthetic techniques on the intraocular pressure changes during laparoscopic surgery in healthy subjects. Propofol IV anesthesia protected against increases in intraocular pressure with pneumoperitoneum and head-down position.

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.