Plasma catecholamines and haemodynamic changes during pneumoperitoneum

[The role of magnesium sulfate in providing hemodynamic stability in patients undergoing laparoscopic surgery: a prospective randomized controlled study]

Introduction

during laparoscopic surgery, carbon dioxide (CO2) insufflation to create pneumoperitoneum increases blood pressure, heart rate and systemic vascular resistance. The purpose of our study was to investigate the efficacy of magnesium sulfate in preventing adverse hemodynamic reactions associated with pneumoperitoneum in patients undergoing laparoscopic cholecystectomy.

Methods

we conducted a prospective, randomized, double-blind, controlled clinical study of patients scheduled for laparoscopic cholecystectomy and divided into two equal groups: the Mg2+ group received slow intravenous magnesium sulfate 50 mg/kg injection prior to pneumoperitoneum insufflation while the S group received the same volume of 0.9 % saline. Our primary endpoint was intraoperative changes in systolic blood pressure (SBP) related to pneumoperitoneum, in particular at 1 minute after insufflation. The secondary endpoints were the haemodynamic effects of pneumoperitoneum in terms of systolic blood pressure (SP), diastolic blood pressure (DP), mean arterial pressure (MAP) and heart rate (HR) from 2 minutes after insufflation to extubation and postoperatively, and the presence of possible adverse reactions related to the administration of magnesium sulphate.

Results

we included 70 patients divided into two groups of 35. SP was significantly higher in the S group at insufflation (T0), 3 min, 4 min and 5 min post-operative, and at 60 min after surgery. HR was significantly higher in patients in the S group compared to the Mg2+ group at 7 min and 8 min after insufflation. No significant differences in DP and MAP measurements were observed between the 2 groups. No adverse reactions related to magnesium administration were reported.

Conclusion

magnesium sulfate administered prior to pneumoperitoneum insufflation provided improved intraoperative hemodynamic stability during laparoscopic surgery.

Review of robot-assisted laparoscopic surgery in management of infant congenital urology: Advances and limitations in utilization and learning

As robotic-assisted (RAL) surgery expanded to treat pediatric congenital disease, infant anatomy and physiology posed unique challenges that prompted adaptations to the technology and surgical technique, which are compiled and reviewed in this manuscript. From the beginning, collaboration with anesthesia is critical for a safe, efficient case including placement of an endotracheal tube rather than a laryngeal mask (LMA) and placement of a nasogastric tube and/or rectal tube to relieve distended stomach or bowel, respectively. Furthermore, end-tidal CO₂ (EtCO₂ ) is important for monitoring and predicting the effects of pneumoperitoneum on caridiovascular physiology, incranial pressure, and risk of acidosis and hypercarbia. Positioning can further exacerbate these effects and affect intra-abdominal working space. For infant robotic pyeloplasty and heminephrectomy, a "beanbag" is commonly used for stabilization in the lateral decubitus position. We advise against the use of a "baby bump" because it brings the bowels and vasculature more anterior than expected. Pnuemoperitoneum pressure of 8-10 mmHg during port placement maximizes safety, but thereafter, the pneumoperitoneum pressure can be minimized to 6-8 mmHg during the procedure without compromising the visual field. Port sites should be marked after insufflation, followed by the open Hasson technique for peritoneal access and port placement under direct vision with intussusception of the trocars to avoid vascular or bowel injury. Additional tips can be obtained through this manuscript, immersive fellowships, and mini-fellowships. Ulitmately, infant robotic surgery has the potential to benefit many children but is presently limited by the lack of pediatric-specific robotic technology and its associated costs.

Pediatric robotic surgery: An overview

Pediatric robotic surgery offers children a minimally invasive approach with numerous advantages over open or thoracoscopic and laparoscopic surgery. However, despite its widespread adoption for adult patients, the utilization of robotic surgery within pediatrics has been relatively slower to progress. This paper provides an overview of pediatric robotic surgery and discusses benefits, limitations, and strategies for successful implementation of robotics within pediatric surgical practice.

Anesthesia for Per-oral endoscopic myotomy (POEM) – not so poetic!

Peroral endoscopic myotomy (POEM) is a promising natural orifice transluminal endoscopic procedure for the treatment of esophageal motility disorders, with similar effectiveness as of Heller myotomy. It is performed under general anesthesia in endoscopy suite. Creation of submucosal tunnel in the esophageal wall is a key component. The continuous insufflation of CO₂ inadvertently tracks into surrounding tissues and leads to capno mediastinum, capno thorax, capno peritoneum, and subcutaneous emphysema. Thus, the challenges, for an anesthesiologist are not only providing remote location anesthesia, increased risk of aspiration during induction, but also early detection of these complications and specific emergency management. Though a therapeutic innovation, POEM remains an interdisciplinary challenge with no specific anesthesia care algorithms and evidence-based recommendations. The purpose of this review is to outline the anesthesia and periprocedural practices based on existing evidence.

Predictive performance of dynamic arterial elastance for arterial pressure response to fluid expansion in mechanically ventilated hypotensive adults: a systematic review and meta-analysis of observational studies

BACKGROUND

Dynamic arterial elastance (Ea_dyn) has been extensively considered as a functional parameter of arterial load. However, conflicting evidence has been obtained on the ability of Ea_dyn to predict mean arterial pressure (MAP) changes after fluid expansion. This meta-analysis sought to assess the predictive performance of Ea_dyn for the MAP response to fluid expansion in mechanically ventilated hypotensive patients.

METHODS

We systematically searched electronic databases through November 28, 2020, to retrieve studies that evaluated the association between Ea_dyn and fluid expansion-induced MAP increases in mechanically ventilated hypotensive adults. Given the diverse threshold value of Ea_dyn among the studies, we only reported the area under the hierarchical summary receiver operating characteristic curve (AUHSROC) as the primary measure of diagnostic accuracy.

RESULTS

Eight observational studies that included 323 patients with 361 fluid expansions met the eligibility criteria. The results showed that Ea_dyn was a good predictor of MAP increases in response to fluid expansion, with an AUHSROC of 0.92 [95% confidence interval (CI) 0.89 to 0.94]. Six studies reported the cut-off value of Ea_dyn, which ranged from 0.65 to 0.89. The cut-off value of Ea_dyn was nearly conically symmetrical, most data were centred between 0.7 and 0.8, and the mean and median values were 0.77 and 0.75, respectively. The subgroup analyses indicated that the AUHSROC was slightly higher in the intensive care unit (ICU) patients (0.96; 95% CI 0.94 to 0.98) but lower in the surgical patients in the operating room (0.72; 95% CI 0.67 to 0.75). The results indicated that the fluid type and measurement technique might not affect the diagnostic accuracy of Ea_dyn. Moreover, the AUHSROC for the sensitivity analysis of prospective studies was comparable to that in the primary analysis.

CONCLUSIONS

Ea_dyn exhibits good performance for predicting MAP increases in response to fluid expansion in mechanically ventilated hypotensive adults, especially in the ICU setting.

Cardiovascular dynamics during peroral endoscopic myotomy for esophageal achalasia: a prospective observational study using non-invasive finger cuff-derived pulse wave analysis

Peroral endoscopic myotomy (POEM) is natural orifice transluminal endoscopic surgery to treat esophageal achalasia. During POEM, cardiovascular dynamics can be impaired by capnoperitoneum, capnomediastinum, and systemic carbon dioxide accumulation. We systematically investigated changes in cardiovascular dynamics during POEM. We included 31 patients having POEM in this single-center prospective observational study. Before and every 5 min during POEM we measured mean arterial pressure (MAP), heart rate (HR), cardiac index (CI), stroke volume index (SVI), and systemic vascular resistance index (SVRI) using non-invasive finger cuff-derived pulse wave analysis. During POEM, the median MAP was higher than the median baseline MAP of 77 (67;86) mmHg. HR (median at baseline: 67 (60;72) bpm), CI (2.8 (2.5;3.2) L/min/m²), SVI (42 (34;51) mL/m²), and SVRI (1994 (1652; 2559) dyn × s × cm^-5 × m^-2) remained stable during POEM. Mixed model-derived 95% confidence limits of hemodynamic variables during POEM were 72 to 106 mmHg for MAP, 65 to 79 bpm for HR, 2.7 to 3.3 L/min/m² for CI, 37 and 46 mL/m² for SVI, and 1856 and 2954 dyn × s × cm^-5 × m^-2 for SVRI. POEM is a safe procedure with regard to cardiovascular dynamics as it does not markedly impair MAP, HR, CI, SVI, or SVRI.

Anesthetic Consideration for Peroral Endoscopic Myotomy

A recent achalasia guideline suggests that peroral endoscopic myotomy (POEM) is a safe option for achalasia that is as effective as Heller myotomy. It is recommended that POEM should be performed under general anesthesia. The incidence of adverse events such as bleeding, perforation, and carbon dioxide insufflation-related complications was lower in POEM under endotracheal general anesthesia than in POEM under sedation. Subcutaneous emphysema, pneumothorax, pneumomediastinum, pneumoperitoneum, and accompanying hemodynamic instability can be caused by carbon dioxide insufflation. Treatment of possible physiological changes and adverse events during the POEM procedure from the point of view of anesthesiologists may give endoscopists a new perspective on improving patient safety. The territory of therapeutic endoscopy can be expanded through cooperation with other departments, including anesthesia services. Efforts to understand different perspectives will certainly help not only secure patient safety but also expand the area of treatment.

Comparative evaluation of dexmedetomidine and labetalol for attenuating hemodynamic stress responses during laparoscopic cholecystectomy in borderline hypertensive patients

OBJECTIVE

Various pharmacological agents have been tried to attenuate the pressor response in laparoscopic cholecystectomy patients. We have compared single pre-induction intravenous injection of dexmedetomidine with labetalol for attenuation of haemodynamic stress response.

METHODS

A total of 160 patients were considered for this prospective, randomized, double blind clinical study done in a single tertiary care institution. Patients were either included in group D, to receive 1.0μg·kg^-1 i.v. dexmedetomidine or group L, to receive 0.3 mg·kg^-1 i.v. labetalol in 100ml of normal saline before induction of anaesthesia. Patient's hemodynamic parameters were noted pre-operatively before starting infusion and at fixed intervals afterwards till extrubation.

RESULTS

After intubation, mean systolic blood pressure (SBP) was higher in patients of group L (128.0 ± 13.866) as compared to group D (123.2 ± 10.672). Afterwards the SBP was comparable until extrubation. Similarly, after intubation patients in group D tended to have lower diastolic pressure (73.1 ± 9.683 vs. 79.2± 14.153, P value .0017) compared to patients in group L. Also, the relative incidence of bradycardia and hypotension was higher in patients who had received inj. labetalol.

CONCLUSION

In patients predisposed to significant fluctuations in blood pressure or heart rate dexmedetomidine may be more suitable than labetalol due to better preservation of normal haemodynamics especially during periods of stress showing a relatively lower incidence of side effects.

Robotic-Assisted Urologic Surgery in Infants: Positioning, Trocar Placement, and Physiological Considerations

Pediatric robotic-assisted laparoscopic procedures are becoming increasingly common. They have been shown to be safe in younger patients, including infants. Successful adoption of robotic-assisted surgery in infants requires an understanding of the technical factors unique to this patient population. This review will delineate the specific considerations to safely perform robotic-assisted laparoscopic procedures in infants, including physiological changes associated with pneumoperitoneum in infants, positioning, trocar placement, and docking.

A comparative study on the prophylactic effects of paracetamol and dexmedetomidine for controlling hemodynamics during surgery and postoperative pain in patients with laparoscopic cholecystectomy

BACKGROUND

Today, the ever-expanding technology is inevitably shadowing on all aspects of human life. This study was aimed to compare the prophylactic effects of paracetamol and dexmedetomidine for controlling hemodynamics during surgery and postoperative pain.

METHODS

The study population consisted of 132 patients aged 18 to 70 years and from both genders, who were candidates for emergency cholecystectomy or elective surgery. Group A consisted of 66 patients who received dexmedetomidine, and Group B included 66 patients with paracetamol administration. The amount of postoperative pain was measured on the basis of visual analog scale, arterial blood pressure, as well as heart rate at recovery and 4, 12, and 24 hours after surgery.

RESULTS

The mean age in the 2 groups was similar and almost equal to 52 years; there was no difference in the sex ratios in both groups (P > .05). Pain score in the paracetamol group was significantly lower than that in the dexmedetomidine group (P = .04); nevertheless, there were no group differences in the mean scores of pain during these hours (P > .05). The median opioid use in 24 hours after operation in the paracetamol group was lower when compared with that in the dexmedetomidine group, and the mean duration of analgesia in the paracetamol group was higher when comparing with dexmedetomidine group. Furthermore, in both groups, mean arterial pressure and preoperative PR interval were similar at various times.

CONCLUSION

The findings demonstrated that both regimens of drugs can control the hemodynamic status of patients during laparoscopic cholecystectomy, which provides effective postoperative analgesia for pain management.

Influence of magnesium sulfate on hemodynamic responses during laparoscopic cholecystectomy: A meta-analysis of randomized controlled studies

BACKGROUND

The impact of magnesium sulfate on hemodynamic responses during laparoscopic cholecystectomy remains controversial. We conduct a systematic review and meta-analysis to explore the influence of magnesium sulfate on hemodynamic responses for laparoscopic cholecystectomy.

METHODS

We search PubMed, EMbase, Web of science, EBSCO, and Cochrane library databases through June 2018 for randomized controlled trials (RCTs) assessing the effect of magnesium sulfate on hemodynamic responses for laparoscopic cholecystectomy. Meta-analysis is performed using the random-effect model.

RESULTS

Four RCTs involving 208 patients are included in the meta-analysis. Overall, compared with control group in laparoscopic cholecystectomy, intravenous magnesium sulfate is associated with systolic blood pressure at 30 minutes [Std. MD = -1.34; 95% confidence interval (95% CI) = -1.86 to -0.82; P < .00001], diastolic blood pressure at 30 minutes (Std. MD = -1.40; 95% CI = -1.86 to -0.94; P < .00001), mean arterial pressure at 30 minutes (Std. MD = -1.19; 95% CI = -1.91 to -0.46; P = .001), systolic blood pressure at 10 minutes (Std. MD = -1.61; 95% CI = -2.08 to -1.13; P < .00001), diastolic blood pressure at 10 minutes (Std. MD = -1.54; 95% CI = -2.68 to -0.40; P = .008), heart rate at 30 minutes (Std. MD = -2.09; 95% CI = -2.87 to -1.32; P < .00001), but results in prolonged extubation time (Std. MD = 0.96; 95% CI = 0.18-1.74; P = .02).

CONCLUSION

Magnesium sulfate can reduce blood pressure, but with the increase in extubation time for laparoscopic cholecystectomy.

Does pneumoperitoneum affect perfusion index and pleth variability index in patients receiving combined epidural and general anesthesia?

Plethysmographic variability index (PVI) is a dynamic index used for the purpose of fluid responsiveness in patients, and the effect of pneumoperitoneum on PVI is still unclear. We therefore attempted to determine whether PVI and perfusion index (PI) change before/after pneumoperitoneum in patients receiving combined epidural and general anesthesia, which is a common anesthesia method with intravenous remifentanil. Twenty patients underwent laparoscopic cholecystectomy or colectomy. Immediately before pneumoperitoneum, variables were measured at baseline I and were then measured every min for 5 min after pneumoperitoneum start. Immediately before pneumoperitoneum release, variables were measured at baseline II and were measured every min for 5 min after pneumoperitoneum release. Compared with baseline I values, after pneumoperitoneum start, significant increases occurred in stroke volume variation (SVV) at 1-5 min, and significant decreases occurred in PI at 1-5 min. PVI did not change. Compared with baseline II values, after pneumoperitoneum release, significant increases occurred in PI at 1-5 min, and significant decreases occurred in PVI at 4-5 min and SVV at 1-5 min. In patients receiving combined epidural and general anesthesia, we newly found that PI decreased but PVI remained unchanged with a sufficient dose of remifentanil and epidural anesthesia that can block noxious stimuli and also most sympathetic activity. Furthermore, we reconfirmed that PI increased and PVI decreased upon release of pneumoperitoneum. PI and PVI values must be estimated cautiously during and after pneumoperitoneum.

Anesthetic considerations for patients with esophageal achalasia undergoing peroral endoscopic myotomy: a retrospective case series review

PURPOSE

Peroral endoscopic myotomy (POEM) is a novel technique for treating esophageal achalasia. During POEM, carbon dioxide (CO₂) is insufflated to aid surgical dissection, but it may inadvertently track into surrounding tissues, causing systemic CO₂ uptake and tension capnoperitoneum. This in turn may affect cardiorespiratory function. This study quantified these cardiorespiratory effects and treatment by hyperventilation and percutaneous abdominal needle decompression (PND).

METHODS

One hundred and seventy-three consecutive patients who underwent POEM were included in this four-year retrospective study. Procedure-related changes in peak inspiratory pressure (p_max), end-tidal CO₂ levels (etCO₂), minute ventilation (MV), mean arterial pressure (MAP), and heart rate (HR) were analyzed. We also quantified the impact of PND on these cardiorespiratory parameters.

RESULTS

During the endoscopic procedure, cardiorespiratory parameters increased from baseline: p_max 15.1 (4.5) vs 19.8 (4.7) cm H₂O; etCO₂ 4.5 (0.4) vs 5.5 (0.9) kPa [34.0 (2.9) vs 41.6 (6.9) mmHg]; MAP 73.9 (9.7) vs 99.3 (15.2) mmHg; HR 67.6 (12.4) vs 85.3 (16.4) min^-1 (P < 0.001 for each). Hyperventilation [MV 5.9 (1.2) vs 9.0 (1.8) L·min^-1, P < 0.001] was applied to counteract iatrogenic hypercapnia. Individuals with tension capnoperitoneum treated with PND (n = 55) had higher peak p_max values [22.8 (5.7) vs 18.4 (3.3) cm H₂O, P < 0.001] than patients who did not require PND. After PND, p_max [22.8 (5.7) vs 19.9 (4.3) cm H₂O, P = 0.045] and MAP [98.2 (16.3) vs 88.6 (11.8) mmHg, P = 0.013] decreased. Adverse events included pneumothorax (n = 1), transient myocardial ischemia (n = 1), and subcutaneous emphysema (n = 49). The latter precluded immediate extubation in eight cases. Postanesthesia care unit (PACU) stay was longer in individuals with subcutaneous emphysema than in those without [74.9 min (34.5) vs 61.5 (26.8 min), P = 0.007].

CONCLUSION

Carbon dioxide insufflation during POEM produces systemic CO₂ uptake and increased intra-abdominal pressure. Changes in cardiorespiratory parameters include increased p_max, etCO₂, MAP, and HR. Hyperventilation and PND help mitigate some of these changes. Subcutaneous emphysema is common and may delay extubation and prolong PACU stay.

Effect of Magnesium Sulfate and Clonidine in Attenuating Hemodynamic Response to Pneumoperitoneum in Laparoscopic Cholecystectomy

BACKGROUND

Pneumoperitoneum in laparoscopic procedures is associated with hemodynamic response, due to the release of catecholamines and vasopressin. Magnesium and clonidine have been used to attenuate such hemodynamic responses by inhibiting release of these mediators. We conducted this randomized, double-blinded study to assess which of the two attenuates hemodynamic response better.

MATERIALS AND METHODS

Ninety American Society of Anesthesiologists health status Classes I and II patients posted for elective laparoscopic cholecystectomy were randomized into three groups of thirty patients each. Group C received injection clonidine 1 μg/kg diluted in 10 mL normal saline over 10 min, prior to pneumoperitoneum. Group M received injection magnesium sulfate 50 mg/kg diluted in 10 mL normal saline over 10 min, prior to pneumoperitoneum. Group NS received 10 mL normal saline intravenously over 10 min, prior to pneumoperitoneum. Hemodynamic parameters were recorded before induction (baseline values), at the end of magnesium sulfate/clonidine/saline administration and before pneumoperitoneum (P0), 5 min (P5), 10 min (P10), 20 min (P20), 30 min (P30), and 40 min (P40) after pneumoperitoneum.

RESULTS

Systolic blood pressure, diastolic blood pressure (DBP), mean arterial pressure (MAP), and heart rate (HR) were all significantly higher in the normal saline group compared to magnesium and clonidine. On comparing patients in Group M and Group C, DBP, MAP, and HR were significantly lower in the magnesium group. Mean extubation time and time to response to verbal commands were significantly longer in the magnesium group.

CONCLUSIONS

Both magnesium and clonidine attenuated the hemodynamic response to pneumoperitoneum. However, magnesium 50 mg/kg, attenuated hemodynamic response better than clonidine 1 μg/kg.

Pediatric anesthesia for minimally invasive surgery in pediatric urology

Laparoscopic or robotic minimally invasive approaches have become the standard of care for many urological pediatric surgical procedures. Anesthetic concerns for conventional and robotic laparoscopy are similar since they both require insufflations of CO₂ to allow visualization of surgical field and perform surgery. Even if required insufflation pressures and volumes are lower in pediatric patients (given the small size of the abdomen and laxity of the abdominal walls), the associated increase of intra-abdominal pressure, along with absorption of CO₂ and surgical positioning requirement, may result in neurendocrine and mechanical impact capable to mine cardiopulmonary function. Moreover, laparoscopic approach may require specific positioning. A correct positioning is essential to allow the surgical team to optimally and safely access to the patient. The knowledge of patient's health status, along with the multiple physiologic changes that can occur and specific potential complications, allow the anesthesiologist to provide a safer an aesthesia.

A comparative study of esmolol and dexmedetomidine on hemodynamic responses to carbon dioxide pneumoperitoneum during laparoscopic surgery

Background:

Carbon dioxide pneumoperitoneum for laparoscopic surgery increases arterial pressures, heart rate (HR), and systemic vascular resistance. In this randomized, single-blind, placebo-controlled clinical study, we investigated and compared the efficacy of esmolol and dexmedetomidine to provide perioperative hemodynamic stability in patients undergoing laparoscopic cholecystectomy.

Methods:

Sixty patients, of either sex undergoing elective laparoscopic cholecystectomy, were randomly allocated into three groups containing twenty patients each. Group E received bolus dose of 500 μg/kg intravenous (IV) esmolol before pneumoperitoneum followed by an infusion of 100 μg/kg/min. Group D received bolus dose of 1 μg/kg IV dexmedetomidine before pneumoperitoneum followed by infusion of 0.2 μg/kg/h. Group S (control) received saline 0.9%.

Results:

Mean arterial pressure and HR in Group E and D were significantly less throughout the period of pneumoperitoneum in comparison to Group S. IV nitroglycerine was required in 45% (9 out of 20) patients in Group S to control intraoperative hypertension, and it was clinically significant in comparison to Group E and D.

Conclusion:

Both esmolol and dexmedetomidine attenuate the adverse hemodynamic response to pneumoperitoneum and provide hemodynamic stability during laparoscopic surgery.

10 cm H2O PEEP application in laparoscopic surgery and cerebral oxygenation: a comparative study with INVOS and FORESIGHT

INTRODUCTION

In the present study, changes in hemodynamic parameters and cerebral oxygen saturation (rSO2) associated with 10 cm H2O PEEP application were investigated, which is assumed beneficial for the respiratory functions and oxygenation during laparoscopic cholecystectomy (LC) applied at 30° head-up left side position. Data gathered via two devices, namely INVOS and FORESIGHT, were compared.

METHODS

After both the ethics committee approval from the hospital and patients' written consents were obtained, patients undergoing elective laparoscopic surgery (only ASA I-II) were randomly divided into two groups (Clinical trials protocol NCT02071550). Sensors of INVOS and FORESIGHT devices were placed on the right side at the forehead region. In total, 11 evaluation periods were formed, namely pre-induction (1st period), post-induction (2nd period), abdominal insufflation outset (3rd period), post-insufflation at 5-min intervals (4th, 5th, 6th, 7th, and 8th period), at the end of insufflation (9th period), at the end of operation (10th period), and at the end of anesthesia (11th period). While one of the groups did not receive PEEP (ZEEP group), the other group received 10 cm H2O along with abdominal insufflation (PEEP group). Demographic data, hemodynamic values, and rSO2 values were recorded for both groups at all 11 periods.

RESULTS

A total of 44 patients in two groups, each group containing 22 individuals, were included in the study. Systolic, diastolic, and mean arterial pressures, etCO2 and SO2 values, and demographic data were found to be similar in both groups. Heart rate was observed to be higher in the PEEP group starting with the PEEP administration. INVOS rSO2 values were found similar in both groups. However, FORESIGHT rSO2 values were found to be higher in the PEEP group compared to the ZEEP group. No patient had cerebral desaturation in both groups throughout the study.

DISCUSSION

Application of PEEP with 10 cm H2O during abdominal insufflation could increase the rSO2 value and heart rate in patients undergoing laparoscopic cholecystectomy. However, all changes observed were within normal limits. FORESIGHT device yielded more compatible results with hemodynamic data compared to INVOS.

Effects of magnesium sulfate on hemodynamic response to carbon dioxide pneumoperitoneum in patients undergoing laparoscopic cholecystectomy

Introduction:

Carbon dioxide pneumoperitoneum (PP) for laparoscopic surgery increases arterial pressure, heart rate, and systemic vascular resistance. In this randomized, double blind, prospective clinical study; we investigated the efficacy of magnesium sulfate to prevent adverse hemodynamic response associated with PP in patients undergoing laparoscopic cholecystectomy.

Materials and Methods:

Sixty patients, of either sex (18-65 years of age), undergoing elective laparoscopic cholecystectomy were randomly allocated in one of the two groups containing 30 patients each. Group M received magnesium sulfate 30 mg/kg intravenously as a bolus before PP. Group C received same volume of 0.9% saline.

Results:

Mean arterial pressure and heart rate were significantly less throughout the period of pneumoperitoneum in patients of group M. Intravenous labetalol was required in 40% (12 out of 30) of the patients in group C to control intraoperative hypertension and it was clinically significant in comparison to group M.

Conclusion:

Magnesium sulfate administered before PP attenuates adverse hemodynamic response and provides hemodynamic stability during PP created for laparoscopic surgery.

Comparative evaluation of dexmedetomidine and esmolol on hemodynamic responses during laparoscopic cholecystectomy

BACKGROUND

The advent of laparoscopic surgery has benefited the patient and surgeon; however creation of pneumoperitoneum for same has bearings during the perioperative period. These effects of pneumoperitoneum are associated with significant haemodynamic changes, increasing the morbidity of the patient.

AIM

The present study compared the efficacy of dexmedetomidine and esmolol on hemodynamic responses during laparoscopic cholecystectomy Materials and Methods: A total of 90 patients aged 20-60 y, American Society of Anaesthesiologists (ASA) physical status I or II, of either sex, planned for laparoscopic cholecystectomy were included. The patients were randomly divided into three groups of 30 each. Group D received dexmedetomidine loading dose 1 mcg/kg over a period of 15 min and maintenance 0.5 mcg/kg/h throughout the pneumoperitoneum. Group E received esmolol loading dose 1 mg/kg over a period of 5 min and maintenance 0.5 mg/kg/h throughout the pneumoperitoneum. Group C received same volume of normal saline.

MEASUREMENTS

Heart rate (HR), systolic blood pressure, diastolic blood pressure and mean arterial pressure (MAP) were recorded preoperative, after study drug, after induction, after intubation, after pneumoperitoneum at 15 min intervals, post pneumoperitoneum and postoperative period after 15 min. Propofol induction dose, intraoperative fentanyl requirement and sedation score were also recorded.

RESULTS

In group D, there was no statistically significant increase in HR and blood pressure after pneumoperitoneum at any time intervals, whereas in Group E, there was a statistical significant increase in MAP after pneumoperitoneum at 15, 45, and 60 min only and HR during the whole pneumoperitoneum period. There was a significant decrease in induction dose of propofol and intraoperative fentanyl requirement in Group D and E, compared to Group C (p<0.0001).

CONCLUSION

Dexmedetomidine is more effective than esmolol for attenuating the hemodynamic response to pneumoperitoneum in elective laparoscopic cholecystectomy. Dexmedetomidine and esmolol also reduced requirements of anaesthetic agents.

A randomized double-blind placebo-controlled clinical study on the effects of gabapentin premedication on hemodynamic stability during laparoscopic cholecystectomy

Background:

Carbon dioxide pneumoperitoneum for laparoscopic surgery increases arterial pressures, heart rate, and systemic vascular resistance. In this randomized double-blind placebo-controlled clinical study, we investigated the efficacy of gabapentin premedication to provide perioperative hemodynamic stability in patients undergoing laparoscopic cholecystectomy.

Materials and Methods:

Sixty patients, of either sex (18–65 years of age) undergoing elective laparoscopic cholecystectomy were randomly allocated to two groups of 30 patients each. Patients of group G received oral gabapentin 900 mg 2 h before induction of anesthesia, while patients in group P received placebo at the same time.

Results:

Mean arterial pressure in patients of group G were significantly lower (P < 0.05) after tracheal intubation and pneumoperitoneum and remained lower, as compared to group P, throughout the pneumoperitoneum. Similarly, heart rate in group G was significantly lower (P < 0.05) after tracheal intubation and pneumoperitoneum and remained lower, in comparison to group P, throughout the peumoperitoneum. Intravenous labetalol was required, to control intraoperative hypertension, in 33.3% (10 out of 30) patients in group P. There was no significant difference in the incidence of adverse effects between the two groups.

Conclusion:

Gabapentin premedication provided perioperative hemodynamic stability during laparoscopic surgery.

Dynamic variables of fluid responsiveness during pneumoperitoneum and laparoscopic surgery

BACKGROUND

Few data exist on dynamic variables predicting fluid responsiveness during laparoscopic surgery. The aim of this study was to explore the effects of laparoscopy on four dynamic variables: respiratory variations in pulse pressure (ΔPP), stroke volume variation by Vigileo/FloTrac (SVV (Vigileo) ), pleth variability index (PVI) and respiratory variations in pulse oximetry plethysmography waveform amplitude (ΔPOP), and their relation to fluid challenges during laparoscopic surgery.

METHODS

ΔPP, SVV (Vigileo) , PVI and ΔPOP were studied in 20 adult patients before and during pneumoperitoneum (10-12 mmHg). During ongoing laparoscopic surgery, relations between the dynamic variables and changes in stroke volume oesophageal Doppler, (SV(OD) ) after fluid challenges (250 ml colloid) were evaluated.

RESULTS

Pneumoperitoneum changed the dynamic variables as follows {mean [95% confidence interval (CI)]}: ΔPP 0.5 (-1.3, 2.3)%, P = 0.53; SVV (Vigileo) 0.6 (-1.3, 2.5)%, P = 0.52; PVI 2.9 (0.4, 5.3)%, P = 0.025. For ΔPOP, median difference (95% CI) was 2.5 (-0.15, 6.7)%, P = 0.058. During laparoscopic surgery, areas under receiver operating characteristics curves (95% CI) were ΔPP 0.53 (0.31-0.75), SVV (Vigileo) 0.74 (0.51-0.90), PVI 0.61 (0.38-0.81), ΔPOP 0.63 (0.40-0.82). Correlation coefficients (P-values) between changes in dynamic variables and changes in SV(OD) were ΔPP r = -0.65, P = 0.009; SVV (Vigileo) r = -0.73, P = 0.002; PVI r = -0.22, P = 0.44; ΔPOP r = -0.32, P = 0.24.

CONCLUSION

ΔPP and SVV (Vigileo) did not change as pneumoperitoneum was established, whereas PVI increased and ΔPOP tended to increase. All four dynamic variables predicted fluid responsiveness relatively poor during ongoing laparoscopic surgery. ΔPP and SVV (Vigileo) tracked changes in stroke volume induced by fluid challenges during ongoing laparascopic surgery, whereas ΔPOP and PVI did not.

Comparative study of intravenously administered clonidine and magnesium sulfate on hemodynamic responses during laparoscopic cholecystectomy

Background:

Both magnesium and clonidine are known to inhibit catecholamine and vasopressin release and attenuate hemodynamic response to pneumoperitoneum. This randomized, double blinded, placebo controlled study has been designed to assess which agent attenuates hemodynamic stress response to pneumoperitoneum better.

Materials and Methods:

120 patients undergoing elective laparoscopic cholecystectomy were randomized into 4 groups of 30 each. Group K patients received 50 ml normal saline over a period of 15 min after induction and before pneumoperitoneum, group M patients received 50 mg/kg of magnesium sulfate in normal saline (total volume 50 ml) over same time duration. Similarly group C1 patients received 1 μg/kg clonidine and group C2 1.5 μg/kg clonidine respectively in normal saline (total volume 50 ml). Blood pressure and heart rate were recorded before induction (baseline value), at the end of infusions and every 5 min after pneumoperitoneum.

Statistical Analysis:

Paired t test was used for intra-group comparison and ANOVA for inter-group comparison.

Results:

Systolic blood pressure was significantly higher in control group as compared to all other groups during pneumoperitoneum. On comparing patients in group M and group C1, no significant difference in systolic BP was found at any time interval. Patients in group C2 showed best control of systolic BP. As compared to group M and group C1, BP was significantly lower at 10, 30 and 40 min post pneumoperitoneum. No significant episodes of hypotension were found in any of the groups. Extubation time and time to response to verbal command like eye opening was significantly longer in group M as compared to other groups.

Conclusion:

Administration of magnesium sulfate or clonidine attenuates hemodynamic response to pneumoperitoneum. Although magnesium sulfate 50 mg/kg produces hemodynamic stability comparable to clonidine 1 μg/kg, clonidine in doses of 1.5μg/kg blunts the hemodynamic response to pneumoperitoneum more effectively.

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.

Magnesium sulphate attenuates arterial pressure increase during laparoscopic cholecystectomy

BACKGROUND

Magnesium is well known to inhibit catecholamine release and attenuate vasopressin-stimulated vasoconstriction. We investigated whether i.v. magnesium sulphate attenuates the haemodynamic stress responses to pneumoperitoneum by changing neurohumoral responses during laparoscopic cholecystectomy.

METHODS

Thirty-two patients undergoing laparoscopic cholecystectomy were randomly assigned to two groups; a control group was given saline, and a magnesium group received magnesium sulphate 50 mg kg(-1) immediately before pneumoperitoneum. Arterial pressure, heart rate, serum magnesium, plasma renin activity (PRA), and catecholamine, cortisol, and vasopressin levels were measured.

RESULTS

Systolic and diastolic arterial pressures were greater in the control group (P<0.05) than in the magnesium group at 10, 20, and 30 min post-pneumoperitoneum. Norepinephrine or epinephrine levels [pg ml(-1), mean (SD)] were higher in the control group than in the magnesium group at 5 [211 (37) vs 138 (18)] or 10 min [59 (19) vs 39 (9)] post-pneumoperitoneum, respectively (P<0.05). In the control group, vasopressin levels [pg ml(-1), mean (SD)] were higher compared with the magnesium group at 5 [64 (18) vs 35 (9), P<0.01] and 10 min [65 (18) vs 47 (11), P<0.05] post-pneumoperitoneum. There were no significant differences between the groups in PRA and cortisol levels.

CONCLUSIONS

I.V. magnesium sulphate before pneumoperitoneum attenuates arterial pressure increases during laparoscopic cholecystectomy. This attenuation is apparently related to reductions in the release of catecholamine, vasopressin, or both.

Pheochromocytoma: diagnostic and therapeutic update

Pheochromocytomas are catecholamine-secreting tumors that arise from chromaffin cells of the sympathetic nervous system. In 80-85% of cases, these tumors are located in the adrenal medulla while the remainder is located in extra-adrenal chromaffin tissues (paragangliomas). Pheochromocytomas account for 6.5% of incidentally discovered adrenal tumors. These tumors may be sporadic or the result of several genetic diseases: multiple endocrine neoplasia type 2, von Hippel-Lindau syndrome, neurofibromatosis type 1, and familial paraganglioma associated with mutations in succinate dehydrogenase subunits. Diagnosis of pheochromocytoma should first be established biochemically by measuring plasma free metanephrines and urinary fractionated metanephrines. The radiological imaging tests of choice are computed tomography (CT) or magnetic resonance imaging (MRI). The first-line specific functional imaging test is scintigraphy with (123)I-metaiodobenzylguanidine (MIBG); if this test is unavailable, scintigraphy with (131)I-MIBG is the second choice. Positron emission tomography (PET) with (18)F-F-fluorodopamine (F-DA) is useful in metastatic disease. The treatment of choice is laparoscopic surgery after adequate alpha adrenergic blockade. Approximately 10% of tumors are malignant. Chemotherapy is used for inoperable disease. Prognosis is good except in malignant disease, in which 5-year survival is less than 50%. The identification of the genes causing hereditary pheochromocytoma has led to changes in the recommendation for genetic testing.

Effects of different anesthetic techniques on antidiuretic hormone secretion during laparoscopic cholecystectomy

BACKGROUND

With the advent of minimally invasive surgery, laparoscopic cholecystectomy has become the standard treatment for symptomatic gallbladder disease. This study aimed to evaluate the effects of using high- versus low-pressure pneumoperitoneum with different anesthetic techniques on hemodynamics and antidiuretic hormone (ADH) secretion.

METHODS

For this prospective study, 60 patients scheduled for elective laparoscopic cholecystectomy were randomly recruited. They were classified into four equal groups: group 1 received general anesthesia with low insufflation pressure (7-9 mmHg); group 2 received general anesthesia with high insufflation pressure (13-15 mmHg); group 3 received general anesthesia in addition to epidural analgesia with low insufflation pressure; and group 4 received general anesthesia in addition to epidural analgesia with high insufflation pressure. Routine intraoperative monitoring was done. The study parameters included heart rate per minute, mean blood pressure (mmHg), and ADH levels (via blood samples) before anesthesia, after induction, 30 and 45 min after abdominal insufflation, and finally, 2 h postoperatively.

RESULTS

The heart rate showed significant increases after pneumoperitoneum in group 2, as compared with the other three groups. Significant differences in mean blood pressure were observed between the study groups. In groups 1 and 4, mean arterial pressure (MAP) significantly decreased after 15 min, and this decrease persisted until the end of the study. In group 2, MAP significantly increased after 15, 30, 45, and 60 min and after 60 min postoperatively. In group 3, MAP significantly decreased after 30 min, and this decrease persisted 1 h after surgery. There were no significant differences in ADH levels before and after induction of anesthesia among any of the study groups. In groups 1 and 4, no statistically significant changes in ADH levels were observed throughout the study period except a mild increase in ADH levels 30 and 45 min after abdominal insufflation. In group 2, after pneumoperitoneum, there was statistically significant increase in ADH levels from the baseline value of 6.422 +/- 0.551 pmol/l to 7.749 +/- 0.635 pmol/l at 30 min and to 6.457 +/- 0.450 pmol/l at 45 min. In group 3, there was a statistically significant decrease in ADH levels from the baseline value of 6.551 +/- 0.356 pmol/l to 6.125 +/- 0.618 pmol/l at 30 min, to 6.118 +/- 0.491 pmol/l at 45 min, and to 6.169 +/- 0.676 pmol/l at 2 h after abdominal insufflation.

CONCLUSION

Pneumoperitoneum can affect several homeostatic systems, leading to hemodynamic and hormonal stress responses. The use of general anesthesia plus epidural analgesia with low insufflation pressure, general anesthesia with low insufflation pressure, or general anesthesia plus epidural analgesia with high insufflation pressure is safe and effective in attenuating these responses.

Effects of Positioning in Laparoscopic Adnexal Surgery on QT Dispersion and Heart Rate Variability Under Sevoflurane Anesthesia

PURPOSE

This study compared the intraoperative changes in the corrected QT dispersion and heart rate variability, predictors of autonomic cardiac function, in laparotomic and laparoscopic adnexal surgery.

MATERIALS AND METHODS

The study was conducted on 46 American Society of Anaesthesiologists class I/II patients, aged 33-51 years, randomized to one of two groups, for elective gynecologic laparotomy or laparoscopy for a benign adnexal mass. Anesthesia was induced and maintained with sevoflurane. Corrected QT dispersion and spectral powers of heart rate variability were measured at baseline, before the induction of anesthesia, and intraoperatively during the adnexal surgery for 15 minutes. The lithotomy and Trendelenburg positions were set at 145 degrees and 30 degrees between thigh and body, respectively. Pneunoperitoneum was established at 12 mm Hg. Laparoscopic surgery was performed via one principal and two ancillary ports. Data were analyzed using the Wilcoxon and Mann-Whitney tests.

RESULTS

A significant increase was observed in intraoperative standard deviation of RR interval values of heart rate variability in both groups compared to preoperative values (P < 0.05). The corrected QT dispersion and low and high frequency heart rate variability showed no significant changes between the two groups.

CONCLUSION

Gynecologic laparoscopy with pneumoperitoneum in the lithotomy and Trendelenburg positions is as safe as laparatomy and seems not to deteriorate the autonomic cardiac function.

Are there changes in leg vascular resistance during laparoscopic cholecystectomy with CO2 pneumoperitoneum?

BACKGROUND

The prompt haemodynamic response to carbon dioxide insufflation during laparoscopic cholecystectomy suggests involvement of the sympathetic system. The aim of the present study was to examine if a change in vascular resistance in leg skeletal muscle could be an important mechanism behind the increased afterload. Furthermore, the arterio-venous differences of the catecholamines were measured in the leg before and during insufflation of carbon dioxide into the peritoneal cavity.

METHODS

Ten patients (ASA I) scheduled for laparoscopic cholecystectomy were included. After induction of anaesthesia, catheters were introduced percutaneously into the radial artery, the femoral vein and the cubital vein for pressure monitoring and blood sampling. The arterial blood flow in the legs was measured by mercury-in-Silastic strain gauge venous occlusion plethysmography. Vascular resistance in the right leg (LVR) was calculated from the formula: (MAP-FVP)/calf blood flow. Measurements were made before and 5 min after insufflation of pneumoperitoneum.

RESULTS

Induction of pneumoperitoneum increased the heart rate (P < 0.05) and also increased mean arterial pressure and femoral vein pressure as well as the calculated leg vascular resistance (P < 0.01). Calf blood flow did not change significantly in either leg. Both arterial and venous noradrenaline concentrations were higher after insufflation (P < 0.01).

CONCLUSION

In patients without heart or lung disease, pneumoperitoneum at an intra-abdominal pressure level of 11-13 mmHg increased the peripheral vascular resistance in the leg while the arterial blood flow in the leg was unaffected. Catecholamine levels increased, but were still low. Therefore, we suggest that the increase in peripheral vascular resistance is caused by increased myogenic activity in the resistance vessels secondary to increased arterial and transmural pressure rather than by increased neurogenic sympathetic activity.

Randomized clinical trial of the effect of pneumoperitoneum on cardiac function and haemodynamics during laparoscopic cholecystectomy

BACKGROUND

Conventional laparoscopic cholecystectomy (CLC) with carbon dioxide pneumoperitoneum may cause major cardiovascular changes. The aim of this study was to evaluate the effect of carbon dioxide pneumoperitoneum and positional changes on haemodynamics and cardiac function in patients assigned randomly to CLC or gasless laparoscopic cholecystectomy (GLC).

METHODS

Fifty patients with American Society of Anesthesiologists physical status I and II were randomly allocated to CLC (28 patients) or GLC (22). Left ventricular end-diastolic and end-systolic diameters, fractional shortening and cardiac output were determined by transoesophageal echocardiography. Measurements were performed before (phase 1) and 10 and 30 min (phases 2 and 3 respectively) after pneumoperitoneum or abdominal wall traction, and after desufflation or release of abdominal wall traction (phase 4) in supine, Trendelenburg and reverse Trendelenburg positions.

RESULTS

Mean diastolic diameter, systolic diameter, mean arterial pressure and heart rate were significantly higher, and fractional shortening was significantly lower, with carbon dioxide pneumoperitoneum than with the gasless procedure during phases 2 and 3. There were no significant differences in cardiac output between the two groups.

CONCLUSION

Carbon dioxide pneumoperitoneum was associated with increased preload and afterload in patients undergoing laparoscopic cholecystecomy. It also decreased heart performance (fractional shortening), but did not affect cardiac output.

Increased spillover of norepinephrine to the portal vein during CO-pneumoperitoneum in pigs

BACKGROUND

Elevated intra abdominal pressure (IAP) during CO2-insufflation has been associated with increased catecholamine concentrations in plasma. We have previously indicated that this may be due to a regional increased spillover from the abdominal region. In this experimental study we investigated catecholamine spillover from the drainage area of the portal vein during CO2-pneumoperitoneum.

METHODS

Eight pigs under general anesthesia were investigated before and after CO2-pneumoperitoneum with an IAP of 15 mmHg. Regional spillover of catecholamines was determined by measuring plasma catecholamine concentrations and flow simultaneously. Plasma concentrations of catecholamines were measured from the portal and femoral veins, the pulmonary and carotid arteries. Flow data were collected with laser-Doppler transit time flow probes around the portal and femoral veins. Cardiac output was measured by the thermo-dilution technique. Estimated spillover was calculated by the veno-arterial difference multiplied by flow.

RESULTS

We found a significant increase in estimated spillover of norepinephrine from the drainage area of the portal vein from 10 (-1.2, 78) ng x min(-1) to 27 (1.8, 475) ng x min(-1)[median (range)] (P = 0.05), but no change in estimated spillover of norepinephrine from the drainage area of the femoral vein. Plasma concentrations of norepinephrine increased in central venous and arterial blood. There was no significant change in epinephrine concentrations in arterial blood.

CONCLUSION

Estimated norepinephrine spillover from the drainage area of the portal vein increased during CO2-pneumoperitoneum in pigs. This may indicate that the increased norepinephrine concentrations found in arterial plasma reflects a local activation of sympathetic nerves in the region of the portal drainage area.

Effects of perioperative alpha1 block on haemodynamic control during laparoscopic surgery for phaeochromocytoma

BACKGROUND

Laparoscopic surgery for phaeochromocytoma can cause excessive catechol amine release with severe hypertension and sinus tachycardia. i.v. calcium antagonists may be used to prevent increases in blood pressure during phaeochromocytoma resection. We investigated the effects of perioperative alpha(1) adrenergic block with urapidil on intraoperative haemodynamic events. The aim was to block the alpha(1) adrenergic receptors before any acute catecholamine release, to prevent any severe rise in blood pressure.

METHODS

Eighteen patients with a phaeochromocytoma received a continuous i.v. infusion of urapidil 10-15 mg h(-1) for 3 days before surgery and until the adrenal gland had been removed. Plasma catecholamine concentrations were measured before surgery, after induction of anaesthesia, at the end of pneumoperitoneal insufflation, during gland manipulation, after gland resection, and in the recovery room after extubation. Arterial pressure was recorded concomitantly. Hypertensive events were treated with boluses of nicardipine with or without esmolol.

RESULTS

All patients had the adrenal tumour removed without any severe rise in blood pressure or other complication. Creation of a pneumoperitoneum and adrenal gland manipulation induced significant catecholamine release associated with hypertension in 6 and 12 patients, respectively. No correlation was found between hypertensive events and plasma catecholamine levels suggesting alpha(1) receptor block with urapidil is efficacious.

CONCLUSIONS

Perioperative alpha(1) block using i.v. urapidil is a safe and efficient alternative during surgical management of phaeochromocytoma.

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.

Effects of intra-abdominal CO2-insufflation on normal and impaired myocardial function: an experimental study

BACKGROUND

Intra-abdominal pressure (IAP) elevation during CO2-pneumoperitoneum increases cardiac afterload and may enhance dysfunction of the already compromised heart. This study focused on the effects of acute IAP increases on left and right ventricular loadings and contractility in the heart with impaired global function.

METHODS

Impairment of myocardial function (IMF) was pharmacologically induced in 16 pigs by administration of halothane and propranolol, while baseline arterial pressure was maintained by intravenous phenylephrine. Intra-abdominal pressure was gradually increased by 10 mmHg up to 30 mmHg in the supine position (IMF group 1, n = 8) or in a head-down tilted position (IMF group 2, n = 8). In two control groups with normal myocardial function, IAP was also increased in the supine position or the head-down tilted position. Cardiac function in all groups was assessed by epicardial echocardiography, intraventricular pressure measurements and pulmonary artery catheterization.

RESULTS

The increase in IAP was accompanied by a transient rise in LV end-systolic wall stress and reduced cardiac output significantly by 16-24% in all groups. In the IMF groups, LV end-diastolic transmural pressure increased by 34-60% to peak values of 24 mmHg, while cross-sectional LV end-diastolic areas remained unchanged. Increases in right ventricular end-diastolic volume and decreases in right ventricular ejection fraction as well as in cardiac output were most pronounced at IAP 20 mmHg and significantly stronger in both IMF groups than in the control groups (P < 0.001).

CONCLUSION

Following the acute elevation of IAP, the right ventricular volume load shifted more extensively in the IMF groups than in the animals with normal myocardial function. Myocardial function in the impaired heart may worsen during IAP elevation due to right ventricular load alterations rather than a LV afterload increase.

Catecholamine release during laparoscopic fundoplication with high and low doses of remifentanil

BACKGROUND

Reports on stress responses to laparoscopic surgery have been conflicting. Depth of anesthesia may influence the neuro-hormonal release, including catecholamines. Opioids depress general sympathetic activation in a dose-dependent manner. We investigated the hypothesis that remifentanil would depress the catecholamine response to pneumoperitoneum and laparoscopic surgery differently with a high dose (HD) compared with a low dose (LD).

METHODS

In a randomized, prospective study we investigated 18 ASA I-II patients undergoing laparoscopic fundoplication with an intra-abdominal pressure of 12 mmHg. The patients were randomized to receive either a LD (0.13 microg kg-1x min-1) or HD (0.39 microg kg-1 x min-1) of remifentanil with a target-controlled infusion (TCI) technique. Bispectral index of EEG (BIS) was maintained at 40-55 by propofol delivered by a TCI system. Arterial catecholamines were analyzed at different times during the procedure.

RESULTS

Norepinephrine increased equally in both groups during pneumoperitoneum and surgical intervention. Epinephrine stayed low in the HD-group, while increasing during surgery in the LD-group.

CONCLUSION

High dose of remifentanil depressed the epinephrine response to pneumoperitoneum and surgery, indicating no general activation of the sympathetic nervous system. Neither a LD nor HD of remifentanil depressed the norepinephrine response during pneumoperitoneum. This suggests a centrally independent release of norepinephrine.

Pathogenesis of CO(2) pneumoperitoneum-induced metabolic hypoxemia in a rabbit model

STUDY OBJECTIVE

To investigate the effects of carbon dioxide (CO(2)) pneumoperitoneum-induced changes in blood gases, acid-base balance, and oxygen homeostasis in rabbits.

DESIGN

Prospective, randomized, controlled study (Canadian Task Force classification I).

SETTING

University training and teaching center.

SUBJECTS

Twenty-six adult female New Zealand white rabbits.

INTERVENTION

Anesthesia and pneumoperitoneum.

MEASUREMENTS AND MAIN RESULTS

In anesthetized rabbits arterial blood gases, acid-base balance, oxygenation values, and lactate concentrations were assayed during 2 hours. Spontaneous breathing, superficial and optimal ventilation without pneumoperitoneum, and with pneumoperitoneum at low (6 mm Hg) and higher (10 mm Hg) insufflation pressures were compared. The CO(2) pneumoperitoneum profoundly affected blood gases, acid-base balance, and oxygen homeostasis. Carboxemia with increasing end-tidal CO(2) and partial pressure of CO(2) (p <0.001), acidosis with decreasing pH (p <0.001), and base deficiency with decreasing actual base excess (p <0.001), standard base excess and standard bicarbonate and acid excess with increasing hydrogen bicarbonate (p <0.05 and <0.01) were found. Desaturation (p <0.01) with decreasing oxyhemoglobin p <0.05) and hemoglobin oxygen affinity (p <0.01) were also found. Carboxemia with acidosis was more pronounced with higher (p <0.01) than with lower (p >0.05) intraperitoneal pressures, and also with spontaneous breathing (p <0.05) and superficial ventilation (p <0.001) than with optimal ventilation, resulting in metabolic hypoxemia.

CONCLUSION

In superficially ventilated and spontaneously breathing rabbits, CO(2) pneumoperitoneum profoundly affected blood gases, acid-base balance, and oxygen homeostasis, resulting in metabolic hypoxemia. With optimal ventilation and low intraperitoneal pressure carboxemia, respiratory acidosis, and changes in oxygen metabolism were minimal.

Skin conductance correlates with perioperative stress

BACKGROUND

Skin conductance (SC) as a measure of emotional state or arousal may be a tool for monitoring surgical stress in anaesthesia. When an outgoing sympathetic nervous burst occurs to the skin, the palmar and plantar sweat glands are filled up, and the SC increases before the sweat is removed and the SC decreases. This creates a SC fluctuation. The purpose of this study was to measure SC during laparoscopic cholecystectomy with propofol and remifentanil anesthaesia and to evaluate whether number and amplitude of SC fluctuations correlate with perioperative stress monitoring.

METHODS

Eleven patients were studied nine times before, during and after anaesthesia. SC was compared to changes in stress measures such as blood pressure, heart rate, norepinephrine and epinephrine levels. SC was also compared to changes in Bispectral index (BIS).

RESULTS

The blood pressure, epinephrine levels and norepinephrine levels were positively correlated with both the number (P < 0.001) and amplitude (P < 0.01) of the SC fluctuations. Moreover, the BIS was positively correlated with the number (P < 0.001) and amplitude (P < 0.001) of the SC fluctuations. Furthermore, during tracheal intubation, the mean levels of the number of SC fluctuations from the 11 patients had the same stress response as measured in changes of the mean levels of norepinephrine. The mean BIS did not show any stress response during tracheal intubation.

CONCLUSION

Number of SC fluctuations may be a useful method for monitoring the perioperative stress.

[Laparoscopic adrenalectomy for pheochromocytoma. Perioperative blockade with urapidil]

OBJECTIVE

To investigate the effects of coeliosurgery by catecholamine assays and the use of urapidil in the management of phaeochromocytoma.

STUDY DESIGN

Prospective cohort study.

PATIENTS

Nine consecutive patients from April 1997 to April 2001.

METHODS

Urapidil (250 mg.j-1) was administered by continuous intravenous infusion three days before surgery and continued throughout anaesthesia. Plasma catecholamine concentrations were measured before surgery, after induction of anaesthesia, during insufflation, after adrenalectomy and in the recovery room. Haemodynamic disorders were treated by nicardipine +/- esmolol bolus doses.

RESULTS

Creation of pneumoperitoneum and adrenal gland manipulations resulted in significant catecholamine releases associated with hypertension in five and eight patients respectively. Preventive urapidil use enabled easy control of blood pressure variations by additive antihypertensive drugs.

CONCLUSION

Perioperative alpha 1 blockade by urapidil enables an effective and easy control of acute preoperative haemodynamic changes.

Preserved CO(2) reactivity and increase in middle cerebral arterial blood flow velocity during laparoscopic surgery in children

In adult patients, the creation of pneumoperitoneum (PP) by means of carbon dioxide (CO(2)) insufflation leads to an increase in cerebral blood flow velocity (CBFV), which is thought to be caused by hypercapnia. We evaluated whether PP leads to an increase of CBFV in children, and whether this increase is directly related to PP. The effects of PP on middle cerebral artery blood flow velocity were investigated in 12 children (mean age 3 yr, range 15-63 mo) undergoing laparoscopic herniorrhaphy under general anesthesia with sevoflurane and nitrous oxide/oxygen. CBFV was measured by using transcranial Doppler ultrasonography. During CO(2) insufflation, the end-tidal CO(2) concentration was kept constant by adjustment of ventilation by increasing minute volume. The CBFV increased significantly at an intraabdominal pressure of 12 mm Hg compared with baseline from 68 +/- 11 cm/s to 81 +/- 12 cm/s (P < 0.05). CO(2) reactivity remained in the normal range (4.0% +/- 1.9%/mm Hg) during PP. We conclude that the induction of PP leads to an increase in middle cerebral artery blood flow velocity in young children independent from hypercapnia, whereas CO(2) reactivity remains normal.

IMPLICATIONS

Laparoscopic surgery is performed frequently in pediatric patients. Cerebral blood flow velocities increase during insufflation of the intraperitoneal cavity for minimally invasive surgery in children. The vasoreactivity as part of the cerebral autoregulation remains unaffected.

Laparoscopic surgery in older adults

This article provides an overview of the current role of laparoscopic surgery in older patients. A retrospective review and analysis of the recent English-language literature on laparoscopic procedures with special attention devoted to those articles focused on geriatric patients was performed. Laparoscopic surgery has rapidly become the fastest-growing discipline within the surgical arena and new applications for laparoscopy continue to be reported. The primary benefits to patients of these developments are smaller scars, decreased postoperative pain, and more-rapid return to normal activity. As society ages, more older patients will present with pathology amenable to laparoscopic intervention. Several aspects of laparoscopy impose unique physiologic stresses and, as such, may alter surgical risk to the geriatric patient. In addition, older patients often have delayed surgical interventions because of more-conservative medical management or unusual symptomatology, which may further complicate the laparoscopic approach. These limitations may alter the risk-to-benefit ratio of laparoscopic versus open procedures. Despite this lack of elucidation of full-risk profiles, laparoscopic approaches should be considered regardless of a patient's age.