Prolonged pneumoperitoneum at 15 mmHg causes lactic acidosis

Assessment of Risk Factors for Iatrogenic Genitourinary Injuries During a Proctectomy

BACKGROUND

It is critical to avoid iatrogenic injuries affecting genitourinary organs in order to prevent postoperative urinary or sexual dysfunction, which lead to lengthier recovery and possibly reoperation.

METHODS

Using the 2016-2019 American College of Surgeons National Quality Improvement Program (ACS NSQIP) Targeted Proctectomy Database, we collated 2577 patients with non-metastatic rectal cancer who underwent a laparoscopic or open proctectomy. Univariate analysis was used to identify differences in perioperative factors and genitourinary injuries (GUIs) between operative approaches, and multivariate logistic regression was used to identify independent risk factors for sustaining an intraoperative GUI.

RESULTS

The rates of preoperative comorbidities were significantly higher among patients who received an open operation. The proportion of GUIs was also significantly higher in this patient population. Multivariate logistic regression demonstrated that patients who underwent a laparoscopic proctectomy were associated with a 51.4% lower risk of sustaining a GUI. Furthermore, >10% body weight loss in the past 6 months and ASA class 3 status were independently associated with a higher risk of GUI regardless of operation type.

CONCLUSION

Patients who undergo a laparoscopic proctectomy are associated with a lower risk of GUI. On the other hand, patients with >10% body weight loss and ASA class 3: Severe Systemic Disease were associated with a higher risk of GUI.

Lower vs standard pressure pneumoperitoneum in robotic-assisted radical prostatectomy: a systematic review and meta-analysis

Robotic-assisted laparoscopic radical prostatectomy (RARP) has been traditionally performed at a pneumoperitoneum insufflation pressure of 12-15 mmHg. This meta-analysis and systematic review aims to assess the current evidence comparing lower to standard pressure pneumoperitoneum in RARP. Systematic searches of MEDLINE, COCHRANE, SCOPUS and EMBASE were performed to identify articles published up until November 2021 comparing lower pressure with standard pressure pneumoperitoneum in RARP. Standard pressure was defined as > 12 mmHg and lower pressure ≤ 12 mmHg. Estimated blood loss, length of operation, length of hospital stay, post-operative ileus, 30-day readmissions, Clavien-Dindo complications and rate of positive surgical margins were extracted as endpoints of interest. Our searches identified 165 abstracts of which 4 articles with 1319 patients were eligible. Cumulative analysis demonstrated reduced length of stay when a lower pressure was used: WMD - 0.23 (- 0.45 to - 0.02) days (p = 0.03) as well as a reduced rate of post-operative ileus: OR 0.41 (0.22 to 0.77) (p = 0.006). There was no significant increase in length of operation WMD - 1.79 (- 15.96 to 12.38) (p = 0.8), estimated blood loss WMD - 2.89 (- 29.41 to 23.62) (p = 0.83), 30-day readmissions or positive surgical margins OR 1.04 (0.78 to 1.38) (p = 0.81) and RD - 0.01 (- 0.04 to 0.01) (p = 0.3) when using a lower pressure. We have demonstrated reduced length of stay and rates of post-operative ileus, when performing RARP at a lower pressure without a significant increase in length of operation, estimated blood loss, positive surgical margins or complications. The recommendation to use lower pressure pneumoperitoneum is moderate to weak and more randomised control trials are required to validate these results.

The effect of different levels of pneumoperitoneum pressures on regional cerebral oxygenation during robotic assisted laparoscopic prostatectomy

Background/aim

This study aimed to evaluate the effect of low- and high-pressure pneumoperitoneum pressures applied during robotic-assisted laparoscopic prostatectomy (RALP) using near-infrared spectroscopy (NIRS) on regional cerebral oxygenation saturation (rSO₂).

Materials and methods

The prospective, comparative, and observational study included patients aged 18–80 years, with the American Society of Anesthesiologists (ASA) physical status I-II, who would undergo elective RALP. The patients were divided into two groups (12 mmHg of pneumoperitoneum pressure group, n=22 and 15 mmHg of pneumoperitoneum pressure group, n=23). Patients’ demographic data, durations of anesthesia, surgery, pneumoperitoneum, and Trendelenburg position, intraoperative estimated blood loss, fluid therapy, urine output, hemodynamic and respiratory data, and rSO₂ values were recorded at regular intervals.

Results

The rSO₂ values increased significantly during the pneumoperitoneum combined with steep Trendelenburg position (from t3 to t6 ) and at the end of the surgery ( t7 ) in both groups, compared to the values 5 min after the onset of pneumoperitoneum in the supine position ( t2 ) (P < 0.05), but no statistical significance was observed between the two groups. No cerebral desaturation was observed in any of our patients. Hemodynamic and respiratory parameters were preserved in both groups. The blood lactate levels were significantly higher in patients operated at high-pressure pneumoperitoneum, compared to those with low-pressure pneumoperitoneum (P < 0.05).

Conclusion

We believe that low-pressure pneumoperitoneum, especially in robotic surgeries, such as robotic-assisted laparoscopic prostatectomy (RALP), can be applied safely.

Laparoscopic liver resection for hepatocellular carcinoma presents less respiratory complications compared with open procedure: A propensity score analysis in the elderly

BACKGROUND

Resection is still the most efficacious treatment to hepatocellular carcinoma (HCC), among which laparoscopic liver resection (LLR) have controversial effects against conventional open procedure (OLR). With a predictable aging tendency of population worldwide, conventional surgical procedures need to be modified to better accommodate elderly patients. Here, we designed a retrospective study based on propensity score analysis, aiming to compare the efficacy of OLR and LLR in patients over 65 years.

METHODS

We retrospectively analyzed patients with an age over 65 who underwent liver resection between January 2015 and September 2018. Patients were divided into the LLR group and OLR group. Short-term and long-term outcomes were compared before and after 1:1 propensity score matching.

RESULTS

Among 240 enrolled patients, 142 were matched with comparable baseline (71 each group). In the matched cohort, LLR group presented with shorter postoperative hospital stay (median 7 vs 6 days, p = 0.003) and fewer respiratory complications (19.7% vs. 7.0%, p = 0.049), especially pleural effusion (15.5% vs. 2.8%, p = 0.020). Meanwhile, LLR had comparable overall hospital cost (6142 vs. 6243 USD, p = 0.977) compared with OLR. The overall survival (OS) and disease-free survival (DFS) did not differ in the two groups.

CONCLUSIONS

Our study showed that laparoscopic liver resection for HCC in the older age groups is associated with shorter postoperative hospital stay and comparable hospital cost compared with open procedure, which could be attributable to less respiratory complications. We recommend that laparoscopy be taken as a priority option for elderly patients with resectable HCC.

Clinical and predictive value of blood lactate levels during cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (HIPEC): a comparative analysis

Postoperative outcome after cytoreductive surgery followed by hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) is strongly related to surgical and anesthesiologic expertise. This study aims to evaluate the clinical significance and prognostic value of lactate levels (LL) measured during CRS-HIPEC on postoperative outcome compared to similar major surgical procedures. Patients who were treated between January and September 2019 at our Institute and met the inclusion criteria were selected. Patients were divided into three groups: group 1: patients who underwent major surgical procedures; group 2: patients who underwent CRS without HIPEC; group 3: patients who underwent CRS with HIPEC. Intraoperative LL were analyzed and correlated with surgical procedure and postoperative outcome. We observed a significant increase of LL during surgical/CRS phase (group 1: p = 0.0001; group 2: p = 0.001; group 3: p = 0.057), rather than during the HIPEC phase in group 3 (p = ns). In patients undergoing CRS and peritonectomies, the mean LL were significantly higher compared to group 1 (p = 0.05). Although not statistically significant, the complication rate was higher in patients with end-CRS lactate values > 2 mMol/l, especially in the group undergoing CRS plus HIPEC. Our pilot study shows that higher LL during peritoneal cancer surgery are expected compared to major surgical procedures. Cytoreductive phase, rather than HIPEC, is related to an increase of LL. The role of LL as an early marker of postoperative complications after CRS-HIPEC should be further verified in properly designed studies.

Impact of pneumoperitoneum on intra-abdominal microcirculation blood flow: an experimental randomized controlled study of two insufflator models during transanal total mesorectal excision : An experimental randomized multi-arm trial with parallel treatment design

OBJECTIVE

To compare changes in microcirculation blood flow (MCBF) between pulsatile and continuous flow insufflation. Transanal total mesorectal excision (TaTME) was developed to improve the quality of the resection in rectal cancer surgery. The AirSeal IFS® insufflator facilitates the pelvic dissection, although evidence on the effects that continuous flow insufflation has on MCBF is scarce.

METHODS

Thirty-two pigs were randomly assigned to undergo a two-team TaTME procedure with continuous (n = 16) or pulsatile insufflation (n = 16). Each group was stratified according to two different pressure levels in both the abdominal and the transanal fields, 10 mmHg or 14 mmHg. A generalized estimating equations (GEE) model was used.

RESULTS

At an intra-abdominal pressure (IAP) of 10 mmHg, continuous insufflation was associated with a significantly lower MCBF reduction in colon mucosa [13% (IQR 11;14) vs. 21% (IQR 17;24) at 60 min], colon serosa [14% (IQR 9.2;18) vs. 25% (IQR 22;30) at 60 min], jejunal mucosa [13% (IQR 11;14) vs. 20% (IQR 20;22) at 60 min], renal cortex [18% (IQR 15;20) vs. 26% (IQR 26;29) at 60 min], and renal medulla [15% (IQR 11;20) vs. 20% (IQR 19;21) at 90 min]. At an IAP of 14 mmHg, MCBF in colon mucosa decreased 23% (IQR 14;27) in the continuous group and 28% (IQR 26;31) in the pulsatile group (p = 0.034).

CONCLUSION

TaTME using continuous flow insufflation was associated with a lower MCBF reduction in colon mucosa and serosa, jejunal mucosa, renal cortex, and renal medulla compared to pulsatile insufflation.

Complications of CO2 insufflation during endoscopic vein harvesting

Over the past few decades, the use of endoscopic harvest of the saphenous vein has gained popularity due to a significant reduction in rates of wound infection and improved cosmesis. The widespread adoption of this technique has introduced a set of complications associated with the use CO₂ insufflation which facilitates exposure during the vein harvest. We describe a case of pneumoperitoneum with systemic acidosis and subcutaneous air following endoscopic vein harvest for coronary artery bypass grafting and review the complications that may arise from CO₂ insufflation during endoscopic vein harvesting.

Preoperative progressive pneumoperitoneum complementing chemical component relaxation in complex ventral hernia repair

BACKGROUND

A rarely used technique for enabling closure of large ventral hernias with loss of domain is preoperative progressive pneumoperitoneum (PPP), which uses intermittent insufflation to gradually stretch the contracted abdominal wall muscles, increasing the capacity of the abdominal cavity. This allows the re-introduction of herniated viscera into the abdominal cavity and assists in closure of giant hernias which may otherwise be considered inoperable.

METHODS

This was a prospective study assessing 16 patients between 2013 and 2015 with multi-recurrent ventral hernia. All patients were treated preoperatively with both Botulinum Toxin A (BTA) injections to the lateral abdominal wall muscles to confer flaccid paralysis, and short-term PPP to passively expand the abdominal cavity. All patients underwent serial abdominal CT imaging, with pre- and post-treatment circumference measurements of the peritoneal cavity and hernia sac, prior to undergoing operative mesh repair of their hernia.

RESULTS

The mean hernia defect size was 236 cm², with mean 28 % loss of domain. The mean overall duration of PPP was 6.2 days. The mean gain in abdominal circumference was 4.9 cm (5.6 %) (p 0.002) after BTA and PPP. Fascial closure and mesh hernia repair were performed in all 16 patients, with no patients suffering from postoperative abdominal hypertension, ventilatory impairment, or wound dehiscence. There are no hernia recurrences to date. Eight patients (50 %) experienced PPP-related complications, consisting of subcutaneous emphysema, pneumothorax, pneumomediastinum, pneumocardium, and metabolic acidosis. No complication required intervention.

CONCLUSIONS

PPP is a useful adjunct in the repair of complex ventral hernia. It passively expands the abdominal cavity, allowing viscera to re-establish right of domain. At the same time, it helps to minimize the risks of postoperative abdominal compartment syndrome and the sequelae of fascial closure under tension. However, its benefits must be carefully weighed with the risk of serious complications, such as infection, perforation, pneumothorax, and pneumomediastinum.

Examining clinical outcomes utilizing low-pressure pneumoperitoneum during robotic-assisted radical prostatectomy

The objective of the study was to assess the safety and clinical outcomes of performing RARP utilizing LPP 12 mmHg with locally confined adenocarcinoma of the prostate. Utilizing the Metro Health RALP database registry and the Michigan Urological Clinic records, we retrospectively reviewed the records of consecutive RALPs performed between December 2012 and March 2015 by a single robotic surgeon. 100 patients underwent RARP utilizing 15 mmHg of standard pressure pneumoperitoneum (SPP) and 100 patients underwent RALP utilizing 12 mmHg lower pressure pneumoperitoneum (LPP). Intraoperative parameters reviewed included operative time (OT) and blood loss (BL). Postoperative parameters reviewed included length of hospital stay (LOS), postoperative ileus, fistulas, urinary retention and hematoma formation. Surgical outcomes reviewed included pathological stage and combined Gleason score. Patient age, BMI, mean combined Gleason score and pathological stage were similar in both groups. Mean OT for the LPP group was 105.49 (66-166) and for the standard pressure pneumoperitoneum (SPP) group 111.31 (61-231) min. The length of stay in both groups was similar, averaging 1.53 (1-6) days for the LPP group and 1.57 (1-6) days for the SPP group. The LPP group had a lower postop ileus rate of 4 vs 8 % in the SPP group, but they were not statistically different. Likewise, the positive margin rate, readmission rate, hematoma rate, retention rate and urinary fistula rate were similar and not statistically different for both groups. Pneumoperitoneum of 12 mmHg is noninferior to 15 mmHg during RARP and does not alter the clinical outcomes.

Pretreatment with endothelium-derived nitric oxide synthesis modulators on gastrointestinal microcirculation during NOTES: an experimental study

BACKGROUND AND STUDY AIMS

On-demand endoscopic insufflation during natural orifice transluminal endoscopic surgery (NOTES) adversely affects microcirculatory blood flow (MBF), even with low mean intra-abdominal pressure, suggesting that shear stress caused by time-varying flow fluctuations has a great impact on microcirculation. As shear stress is inversely related to vascular diameter, nitric oxide (NO) production acts as a brake to vasoconstriction.

OBJECTIVE

To assess whether pretreatment by NO synthesis modulators protects gastrointestinal MBF during transgastric peritoneoscopy.

METHODS

Fourteen pigs submitted to cholecystectomy by endoscope CO₂ insufflation for 60 min were randomized into 2 groups: (1) 150 mg/kg of N-acetyl cysteine (NAC, n = 7) and (2) 4 ml/kg of hypertonic saline 7.5 % (HS, n = 7), and compared to a non-treated NOTES group (n = 7). Five animals made up a sham group. Colored microspheres were used to assess changes in MBF.

RESULTS

The average level of intra-abdominal pressure was similar in all groups (9 mmHg). In NOTES group microcirculation decrease compared with baseline was greater in renal cortex, mesocolon, and mesentery (41, 42, 44 %, respectively, p < 0.01) than in renal medulla, colon, and small bowel (29, 32, 34, respectively, p < 0.05). NAC avoided the peritoneoscopy effect on renal medulla and cortex (4 and 14 % decrease, respectively) and reduced the impact on colon and small bowel (20 % decrease). HS eliminated MBF changes in colon and small bowel (14 % decrease) and modulated MBF in renal medulla and cortex (19 % decrease). Neither treatment influenced mesentery MBF decrease.

CONCLUSIONS

Both pretreatments can effectively attenuate peritoneoscopy-induced deleterious effects on gastrointestinal MBF.

Effect of transgastric natural orifice transluminal endoscopic surgery peritoneoscopy on abdominal organ microcirculation: an experimental controlled study

BACKGROUND AND AIMS

On-demand insufflation during endoscopic peritoneoscopy causes wide variations in intra-abdominal pressure. Its effects on splanchnic microcirculation may differ from those of steady intra-abdominal pressure, because pressure characteristics affect crucial intravascular hemodynamic forces--pressure and shear--adapting flow to local metabolic needs. Our aim was to assess the effect of natural orifice transluminal endoscopic surgery (NOTES) peritoneoscopy on splanchnic microcirculatory blood flow.

METHODS

Twenty-one swine were randomized to the following: cholecystectomy by transgastric NOTES (n = 8), cholecystectomy by standard laparoscopy (Lap) (n = 8), and a sham group (n = 5). During NOTES, CO2 was manually insufflated with a maximum allowed pressure of 30 mm Hg. In the Lap group, intra-abdominal pressure was maintained at 14 mm Hg. Systemic hemodynamics were measured, and microcirculatory blood flow was quantified by using colored microspheres.

RESULTS

Mean intra-abdominal pressure was lower in NOTES than in the Lap group (P = .038). In both groups, cardiac index and preload remained unchanged, whereas systemic vascular resistances increased over time, with a lesser increase in the Lap group (2-way analysis of variance; P = .041). In pneumoperitoneum groups, microcirculatory blood flow decreased similarly in the renal medulla, stomach, small bowel, colon, and mesocolon by 30%, 45%, 34%, 32%, and 37%, respectively. In NOTES, there was a greater microcirculatory blood flow decrease in the renal cortex (NOTES 41% vs Lap 35%; P = .044) and mesentery (NOTES 44% vs Lap 38%; P = .041).

CONCLUSIONS

These findings suggest that both types of pneumoperitoneum have similar physiologic effects on microcirculatory blood flow. However, on-demand pneumoperitoneum (NOTES group) caused a greater microcirculatory blood flow decrease in areas with low metabolic needs, redistributing blood flow toward metabolically active areas.

Anaesthesia Management of a Patient with Incidentally Diagnosed Diaphragmatic Hernia During Laparoscopic Surgery

Diaphragmatic hernia is usually congenital. However, it is rarely traumatic and can stay asymptomatic. In this report, we aimed to present the anaesthetic management of a patient with diaphragmatic hernia due to previous trauma (14 years ago), which was diagnosed incidentally during surgery for rectal cancer. The patient (53 years, 56 kg, 165 cm, American Society of Anaesthesiologist (ASA) II), to whom laparoscopic surgery was planned because of rectal cancer, had a history of falling from a height 14 years ago. Preoperatively, the patient did not have any sign except small right diaphragmatic elevation on the chest x-ray. After induction, maintenance of anaesthesia was continued with sevoflurane and O2/N2O. The patient was given a 30° Trendelenburg position. When the trochars were inserted by the surgeon, the diaphragmatic hernia was seen on the right part of the diaphragm, which was hidden by the liver. The surgery was continued laparoscopically but with low pressure (12 mmHg), because the patient did not have any haemodynamic and respiratory instability. The patient, who had stable haemodynamic parameters and no respiratory complications during the operation, was transferred to the ward for monitorised care. Traumatic diaphragmatic hernias can be detected incidentally after a long period of acute event. In our case, it was diagnosed during laparoscopic surgery. The surgery was completed with appropriate and careful haemodynamic monitoring and low intra-abdominal pressure under inhalational anaesthesia without any impairment in the patient's haemodynamic and respiratory parameters.

Randomized comparison of surgical stress and the nutritional status between laparoscopy-assisted and open distal gastrectomy for gastric cancer

BACKGROUND

Laparoscopy-assisted distal gastrectomy (LADG) for gastric cancer may prevent the development of an impaired nutritional status due to reduced surgical stress compared with open distal gastrectomy (ODG).

METHODS

This study was performed as an exploratory analysis of a phase III trial comparing LADG and ODG for stage I gastric cancer during the period between May and December of 2011. All patients received the same perioperative care via fast-track surgery. The level of surgical stress was evaluated based on the white blood cell count and the interleukin-6 (IL-6) level. The nutritional status was measured according to the total body weight, amount of lean body mass, lymphocyte count, and prealbumin level.

RESULTS

Twenty-six patients were randomized to receive ODG (13 patients) or LADG (13 patients). The baseline characteristics and surgical outcomes were similar between the two groups. The median IL-6 level increased from 0.8 to 36.3 pg/dl in the ODG group and from 1.5 to 53.3 pg/dl in the LADG group. The median amount of lean body mass decreased from 48.3 to 46.8 kg in the ODG group and from 46.6 to 46.0 kg in the LADG group. There are no significant differences between two groups.

CONCLUSIONS

The level of surgical stress and the nutritional status were found to be similar between the ODG and LADG groups in a randomized comparison using the same perioperative care of fast-track surgery.

Comparison of oxidative stress status in dogs undergoing laparoscopic and open ovariectomy

The present study evaluated and compared the oxidative stress status of dogs undergoing laparoscopic or open ovariectomy. Twelve healthy female dogs were divided into two groups according to the type of the surgical procedure, laparoscopic or open ovariectomy. Plasma total oxidant status (TOS), total antioxidant status (TAS) and oxidative stress index (OSI) levels for the evaluation of oxidative stress were determined. Increases in plasma TOS and OSI levels and decreases in TAS levels were observed in both groups after surgery. The TOS level was significantly lower in the laparoscopic ovariectomy group compared with the open surgery group. Laparoscopic ovariectomy is a safe and beneficial surgical alternative to traditional ovariectomy with respect to oxidative stress status in dogs.

Anaesthesia for Robotic Gynaecological Surgery

Robotic surgery is gaining widespread popularity due to advantages such as reduced blood loss, reduced postoperative pain, shorter hospital stay and better visualisation of fine structures. Robots are being used in urological, cardiac, thoracic, orthopaedic, gynaecological and general surgery. Robotic surgery received US Food and Drug Administration approval for use in gynaecological surgery in 2005.

The various gynaecological robotic operations being performed are myomectomy, total and supracervical hysterectomy, ovarian cystectomy, sacral colpopexy, tubal reanastomosis, lymph node dissection, surgery of retroperitoneal ectopic pregnancy, Moskowitz procedure and endometriosis surgery.

The anaesthetic considerations include difficult access to the patient intraoperatively, steep Trendelenburg position, long surgical duration and the impact of pneumoperitoneum. We highlight the complications encountered in these surgeries and methods to prevent these complications.

Robotic gynaecological surgery can be safely performed after considering the physiological effects of the steep Trendelenburg position and of pneumoperitoneum. The benefits of the surgical procedure should be weighed against the risks in patients with underlying cardiorespiratory problems.

Incidence of gastric mucosal injury as measured by reactance in critically ill patients

Gastric reactance has been proposed as a measure of mucosal ischemic injury in the critically ill. The purpose of this study was to evaluate the incidence of gastric mucosal injury as measured by gastric reactance in different subgroups of critical patients. We studied 100 adult patients admitted to 7 different hospital intensive care units, requiring a nasogastric tube. Gastric impedance measurements were continuously obtained from each patient for 24 hours. Patients were managed based on conventional protocols by hospital staff, blinded to the changes in gastric impedance parameters. The low-frequency central reactance (X L) reflects tissue edema caused by prolonged ischemia. The previously reported threshold of X L ≥ 13 - jΩ was used to classify injured mucosa; 80% of all patients had mean X L above this threshold. No significant differences were found in the incidence of mucosal ischemia between medical versus surgical, hemodynamic versus respiratory or neurological patients. Significant lower urine output was found in patients with X L above threshold (P < .01); also, there was a significant effect of fluid balance in those patients (P < .05). More complicated patients had higher average reactance. This study shows that gastric ischemia as estimated by gastric reactance has a very high incidence in the critically ill, independently of the reason for admission. High reactance is related with higher morbidity in agreement with other reports using different methods of assessing splanchnic hypoperfusion in this patient population.

The effect of heating insufflation gas on acid-base alterations and core temperature during laparoscopic major abdominal surgery

Background

Carbon dioxide (CO₂) has different biophysical properties under different thermal conditions, which may affect its rate of absorption in the blood and the related adverse events. The present study was aimed to investigate the effects of heating of CO₂ on acid-base balance using Stewart's physiochemical approach, and body temperature during laparoscopy.

Methods

Thirty adult patients undergoing laparoscopic major abdominal surgery were randomized to receive either room temperature CO₂ (control group, n = 15) or heated CO₂ (heated group, n = 15). The acid-base parameters were measured 10 min after the induction of anesthesia (T1), 40 min after pneumoperitoneum (T2), at the end of surgery (T3) and 1 h after surgery (T4). Body temperature was measured at 15-min intervals until the end of the surgery.

Results

There were no significant differences in pH, PaCO₂, the apparent strong ion difference, the strong ion gap, bicarbonate ion, or lactate between two groups throughout the whole investigation period. At T2, pH was decreased whereas PaCO₂ was increased in both groups compared with T1 but these changes were not significantly different. Body temperatures in the heated group were significantly higher than those in the control group from 30 to 90 min after pneumoperitoneum.

Conclusions

The heating of insufflating CO₂ did not affect changes in the acid-base status and PaCO₂ in patients undergoing laparoscopic abdominal surgery when the ventilator was set to maintain constant end-tidal CO₂. However, the heated CO₂ reduced the decrease in the core body temperature 30 min after the pneumoperitoneum.

Inclusion of a nitric oxide congener in the insufflation gas repletes S-nitrosohemoglobin and stabilizes physiologic status during prolonged carbon dioxide pneumoperitoneum

A method to maintain organ blood flow during laparoscopic surgery has not been developed. Here we determined if ethyl nitrite, an S-nitrosylating agent that would maintain nitric oxide bioactivity (the major regulator of tissue perfusion), might be an effective intervention to preserve physiologic status during prolonged pneumoperitoneum. The study was conducted on appropriately anesthetized adult swine; the period of pneumoperitoneum was 240 minutes. Cohorts consisted of an anesthesia control group and groups insufflated with CO2 alone or CO2 containing fixed amounts of ethyl nitrite (1-300 ppm). Insufflation with CO2 alone produced declines in splanchnic organ blood flows and it reduced circulating levels of S-nitrosohemoglobin (i.e., nitric oxide bioactivity); these reductions were obviated by ethyl nitrite. In a specific example, preservation of kidney blood flow with ethyl nitrite kept serum creatinine and blood urea nitrogen concentrations constant whereas in the CO2 alone group both increased as kidney blood flow declined. The data indicate ethyl nitrite can effectively attenuate insufflation-induced decreases in organ blood flow and nitric oxide bioactivity leading to reductions in markers of acute tissue injury. This simple intervention provides a method for controlling a major source of laparoscopic-related morbidity and mortality: tissue ischemia and altered postoperative organ function.

Systematic review of oxidative stress associated with pneumoperitoneum

Background

There have been several reports of ischaemic complications after routine laparoscopy. The aim of this review was to investigate the relationship between this oxidative stress and pneumoperitoneum.

Methods

Medline, Medline in-process, The Cochrane Library, PubMed and EMBASE were searched for papers on oxidative stress and pneumoperitoneum, from 1947 to March 2008 with no language restriction or restriction on trial design. Papers that did not investigate pneumoperitoneum as a causative factor, or did not report outcome measures related to oxidative stress, were excluded.

Results

A total of 73 relevant papers were identified: 36 animal studies, 21 human clinical trials, nine case reports, five review articles and two comments. Pneumoperitoneum causes a reduction in splanchnic blood flow, resulting in biochemical evidence of oxidative stress in a pressure- and time-dependent manner. There is evidence that the use of carbon dioxide for insufflation is contributory. Several measures proposed to minimize the oxidative stress have shown promise in animal studies, but few have been evaluated in the clinical setting.

Conclusion

There is an increasing body of evidence, mainly from animal studies, that pneumoperitoneum decreases splanchnic perfusion with resulting oxidative stress. It is now appropriate to investigate the clinical significance of pneumoperitoneum-associated oxidative stress.

Effects of adding small amounts of oxygen to a carbon dioxide-pneumoperitoneum of increasing pressure in rabbit ventilation models

OBJECTIVE

To evaluate the metabolic consequences of the addition of oxygen to the CO(2)-pneumoperitoneum.

DESIGN

Prospective randomized study in rabbits. After 30 minutes of ventilation pneumoperitoneum was maintained for 90 minutes with pure CO(2) or CO(2) with 2% or 6% of oxygen. The intraperitoneal pressure was increased from 10 to 15 and 20 mm Hg every 30 minutes. Ventilation rate was either fixed or a progressive hyperventilation. End points were changes in arterial blood gases (Pco(2), Po(2)), pH, acid-base balance (actual base excess [ABE], standard bicarbonate [SBC], standard base excess [SBE], hydrogen carbonate [HCO(3)(-)], concentration of total carbon dioxide [Tco(2)]); oxygen and oximetry (oxyhemoglobin [O(2)Hb], oxygen saturation [So(2)], reduced hemoglobin [RHb], total oxygen concentration [To(2)], and oxygen tension at half saturation assessing hemoglobin oxygen affinity [p50]); and lactate concentrations assayed every 15 minutes.

SETTING

University research center.

ANIMALS

Twenty-four adult female New Zealand white rabbits.

INTERVENTION(S)

Anesthesia, mechanical ventilation, and pneumoperitoneum.

RESULT(S)

The effects of CO(2)-pneumoperitoneum on all end points increased with the elevated intraperitoneal pressure and were more pronounced when ventilation was fixed. Changes were less when 2% or 6% of oxygen had been added to the CO(2)-pneumoperitoneum. With use of logistic regression, the addition of oxygen, intraperitoneal pressure, and ventilation were found to be independent variables affecting Pco(2), pH, ABE, SBE, HCO(3)(-), O(2)Hb, So(2), p50, and end-tidal CO(2).

CONCLUSION(S)

The metabolic consequences of the combined effect of increased intraperitoneal pressure and CO(2)-pneumoperitoneum were less when 2% to 6% of oxygen was added or when animals were hyperventilated. We suggest that metabolic and mesothelial hypoxemia caused by CO(2) absorption can be reduced by adding small amounts of oxygen and by hyperventilation.

A brief review: anesthesia for robotic prostatectomy

A brief review of the anesthesia for robotic prostatectomies, with a description of the procedure, the physiological principles involved, anesthetic management, problems, and possible complications.

Positive end-expiratory pressure improves arterial oxygenation during prolonged pneumoperitoneum

BACKGROUND

Laparoscopic surgery usually requires the use of a pneumoperitoneum by insufflating gas in the peritoneal space. The gas most commonly used for insufflation is carbon dioxide. Increased intra-abdominal pressure causes cephalad displacement of the diaphragm resulting in compressed lung areas, which leads to formation of atelectasis, especially during mechanical ventilation. The aim of this prospective study was to investigate the effect of prolonged intraperitoneal gas insufflation on arterial oxygenation and hemodynamics during mechanical ventilation with and without positive end-expiratory pressure (PEEP).

METHODS

Twenty patients undergoing totally endoscopic robot-assisted radical prostatectomy were randomly allocated to one of two groups. In the PEEP group (n = 10) a constant PEEP of 5 cmH(2)O was used, whereas in the ZPEEP group (n = 10) no PEEP was used.

RESULTS

Application of PEEP (5 cmH(2)O) resulted in significantly higher P(a)O(2) levels after 3 h (182 +/- 49 vs. 224 +/- 35 mmHg) and 4 h (179 +/- 48 vs. 229 +/- 29 mmHg) of pneumoperitoneum; after desufflation, P(a)O(2) values decreased significantly below preinsufflation values. While there were no significant differences in heart rate, central venous pressure (CVP) and mean arterial blood pressure (MAP) during pneumoperitoneum between both groups, baseline values in CVP and MAP differed significantly between both groups with higher levels in the ZPEEP group.

CONCLUSION

The application of a constant positive airway pressure of 5 cmH(2)O preserves arterial oxygenation during prolonged pneumoperitoneum.

A method to attenuate pneumoperitoneum-induced reductions in splanchnic blood flow

OBJECTIVE

To determine if increasing nitric oxide bioactivity by inclusion of ethyl nitrite (ENO) in the insufflation admixture would attenuate pneumoperitoneum-induced decreases in splanchnic perfusion.

SUMMARY BACKGROUND DATA

Organ blood flow is reduced during pneumoperitoneum and can contribute to laparoscopy-associated morbidity and mortality. Previous attempts to control such decreases in flow have been ineffective.

METHODS

Laser-Doppler flow probes were placed on the liver and right kidney of anesthetized pigs. After a baseline recording period, animals were insufflated to a final intraperitoneal pressure of 15 mm Hg. Group one received CO2 (standard practice), whereas group 2 received CO2 plus 100 ppm ENO. Insufflation was maintained for 60 minutes and then the abdomen was manually deflated; monitoring was continued for another 60 minutes.

RESULTS

CO2 insufflation (n = 5) cut liver blood flow in half; liver flow remained at this level throughout the postinsufflation period. Inclusion of 100 ppm ENO (n = 6) attenuated both the acute and prolonged blood flow decreases. Statistical modeling of the data showed that, on average, liver blood flow was 14.3 U/min higher in the ENO pigs compared with the CO2 group (P = 0.0454). In contrast, neither treatment significantly altered kidney blood flow (P = 0.6215).

CONCLUSION

The data indicate that ENO can effectively attenuate pneumoperitoneum-induced blood flow decreases within the peritoneal cavity. The result suggests a novel therapeutic method of regulating hemodynamic changes during laparoscopic procedures.

Peritoneal pH during laparoscopy is dependent on ambient gas environment: helium and nitrous oxide do not cause peritoneal acidosis

BACKGROUND

Little is know about the effects of different insufflation gases on peritoneal pH during laparoscopy. However, these changes may influence the intracellular signalling system, resulting in altered cell growth or adhesiveness. The aim of this study was to determine the effects of carbon dioxide (CO(2)), nitrous oxide (N(2)O), and helium (He) on parietal and visceral peritoneal pH. The effect of different intraabdominal pressures on parietal and visceral peritoneal pH was also examined.

METHODS

We conducted both an ambient gas study and a pressure study. For the ambient gas study, 20 pigs were divided into the following four groups: (a) CO(2), (b) He, (c) N(2)O, and (d) abdominal wall lift (Lift) laparoscopy. Parietal and visceral peritoneal pH were measured at 15 min intervals for 180 min. For the pressure study, 15 pigs were divided into the following three groups: (a) CO(2), (b) He, (c) N(2)O laparoscopy. Baseline values were established for parietal and visceral peritoneal pH. Intraabdominal pressure was then increased stepwise at 1-mmHg intervals to 15 mmHg. After pressure was maintained for 15 min at each setting, parietal and visceral peritoneal pH were measured.

RESULTS

Ambient gas environment was the major determinant of parietal peritoneal pH. Carbon dioxide caused parietal peritoneal acidosis. Helium, N(2)O, and Lift caused alkalotic parietal peritoneal pH. Intraabdominal pressure had a minor effect on parietal peritoneal pH. At higher intraabdominal pressure (12-15 vs 5-8 mmHg), CO(2) caused a slight decrease in parietal peritoneal pH, whereas N(2)O and He caused a slight increase in parietal peritoneal pH. Visceral peritoneal pH remained relatively unaffected during all studies.

CONCLUSIONS

Parietal peritoneal pH during laparoscopy was highly dependent on the ambient gas environment. The effect of intraabdominal pressure on parietal peritoneal pH was of minor significance. Carbon dioxide caused a slight worsening of parietal peritoneal acidosis at higher intraabdominal pressure, whereas, N(2)O, He, and Lift did not cause parietal peritoneal acidosis.

Systemic and peritoneal angiogenic response after laparoscopic or conventional colon resection in cancer patients: a prospective, randomized trial

PURPOSE

Angiogenesis is essential for wound healing. Vascular endothelial growth factor and endostatin are both endogenous angiogenic factors thought to be involved in the initiation and termination of angiogenesis. The aim of this study was to assess the local and systemic angiogenic profile in patients undergoing laparoscopic or open surgery for colon cancer.

METHODS

Patients with primary colon carcinoma were prospectively randomized to curative laparoscopic (n = 12) or conventional (n = 14) resection. Vascular endothelial growth factor and endostatin levels in serum and wound fluid were investigated.

RESULTS

In both groups vascular endothelial growth factor levels in wound fluid were significantly higher than postoperative serum levels, whereas endostatin levels in wound fluid were lower than serum levels and decreased progressively after surgery. The vascular endothelial growth factor levels in wound fluid measured at Day 4 were significantly higher in the laparoscopy group than in the laparotomy patients.

CONCLUSIONS

Wound healing is associated with a strong local increase in pro-angiogenic factors and a decrease in antiangiogenic factors. The investigation of locally produced factors offered greater insight into the process of angiogenesis during wound healing than could be acquired from the circulation.

Carbon dioxide pneumoperitoneum causes severe peritoneal acidosis, unaltered by heating, humidification, or bicarbonate in a porcine model

BACKGROUND

Carbon dioxide (CO(2)) is the most common gas used for insufflation in laparoscopy, but its effects on peritoneal physiology are poorly understood. This study looks at the changes in peritoneal and bowel serosal pH during CO(2) pneumoperitoneum, and whether heating and humidification with or without bicarbonate alters the outcomes.

METHODS

Twenty-one pigs divided into four groups as follows: (1) standard (STD) laparoscopy (n = 5); (2) heated and humidified (HH) laparoscopy (n = 6); (3) heated and humidified with bicarbonate (HHBI) laparoscopy (n = 5); and (4) laparotomy (n = 5). Peritoneal pH, bowel serosal pH, and arterial blood gas (ABG) were obtained at 15-min intervals for 3 h.

RESULTS

Severe peritoneal acidosis (pH range 6.59-6.74) was observed in all laparoscopy groups, and this was unaltered by heating and humidification or the addition of bicarbonate. Bowel serosal acidosis was observed in all laparoscopy groups with onset of pneumoperitoneum, but it recovered after 45 minutes. No significant changes in peritoneal or bowel serosal pH were observed in the laparotomy group.

CONCLUSION

CO(2) pneumoperitoneum resulted in severe peritoneal acidosis that was unaltered by heating and humidification with or without bicarbonate. Alteration in peritoneal pH may conceivably be responsible for providing an environment favorable for tumor-cell implantation during laparoscopy.

Effects of carbon dioxide pneumoretroperitoneum on free radical formation in remote organs and use of verapamil as an antioxidant

BACKGROUND AND PURPOSE

Pneumoretroperitoneum (Prp) acts as an ischemia/reperfusion (I/R) model. Ischemia/reperfusion (I/R) injury causes production of reactive oxygen species, which affect organs remote from the sites of I/R. The aim of this study was to assess the remote organ changes after Prp and to explore the effects of antioxidants.

MATERIALS AND METHODS

Eighteen adult rabbits were randomized to three groups, each consisting of six rabbits. Group I (control) underwent balloon dissection of the left retroperitoneal space without gas insufflation. In group II (Prp), carbon dioxide at 10 mm Hg was applied for 2 hours after the balloon dissection (ischemia period) and for 1 hour after desufflation (reperfusion period). In group III (Prp + antioxidant), 5 minutes before the experiment, verapamil at 0.2 mg/kg was given intravenously and the same procedure was employed as in group II. Hepatic, pulmonary, opposite kidney, and treated kidney malondialdehyde (MDA) and reduced glutathione (GSH) levels were evaluated to show response to Prp.

RESULTS

Pneumoretroperitoneum exerted oxidative stress on all tissues with an increase of MDA (P < 0.05) and a decrease of GSH (P < 0.05). The verapamil-treated group showed lower values of MDA (P < 0.05) and higher values of GSH (P < 0.05) than group II.

CONCLUSION

Pneumoretroperitoneum increased oxidative stress in all remote organs tested. Verapamil reduced the oxidative stress. We concluded that Prp should be employed carefully in patients with limited vital organ capacity. Verapamil administration may be considered for protection against tissue injury attributable to oxidative stress in these patients.

A review of laparoscopy for non-obstetric–related surgery during pregnancy

PURPOSE

Similar to the general population, parturients (and their fetuses) could benefit from the reduced manipulation associated with laparoscopy. The purpose of this article is to review the current state of knowledge (both clinical and experimental) with respect to the fetal effects of maternal laparoscopy for non-obstetric-related surgery during pregnancy.

METHODS

Human and experimental animal results are examined, and we present preliminary data from our own laboratory.

CONCLUSIONS

Future experiments are proposed to further develop and refine standards of care for general surgeons and obstetricians who are presented with gravid females in abdominal distress.

Peritoneal response to pneumoperitoneum and laparoscopic surgery

BACKGROUND

It is generally believed that laparoscopic surgery inflicts less trauma to the peritoneum than open surgery. Local peritoneal fibrinolysis is a critical factor in adhesion development. The objective was to investigate fibrinolytic changes in the peritoneum during laparoscopic and open surgery.

METHODS

At laparotomy (n = 10) peritoneal biopsies were taken at opening of the abdomen and just before closure. At laparoscopy (n = 12) opening peritoneal biopsies were taken after carbon dioxide insufflation, and closure biopsies just before exsufflation. Tissue concentrations of tissue-type plasminogen activator (tPA), plasminogen activator inhibitor type 1 (PAI-1) and the resulting tPA activity were assayed.

RESULTS

Concentrations of tPA in peritoneal tissue declined during operation in both groups, but significantly so only in the laparotomy group (- 53 per cent; P = 0.01). PAI-1 levels were higher in opening biopsies from the laparoscopy group (P = 0.004). There was an increase in PAI-1 concentration during laparotomy, but not during laparoscopy. At the end of the operation, there was no difference between the groups. The resulting tPA activity did not differ between groups at opening or closure. In both groups there was a significant decline during operation (laparotomy: - 59 per cent, P = 0.02; laparoscopy: - 63 per cent, P = 0.01).

CONCLUSION

These findings indicate that the peritoneal response to open and laparoscopic surgery is similar. The initial rise in peritoneal PAI-1 concentration during laparoscopy suggests an adverse effect of carbon dioxide insufflation, which might affect peritoneal repair.

Effects of prolonged pneumoperitoneum on hemodynamics and acid-base balance during totally endoscopic robot-assisted radical prostatectomies

Laparoscopic techniques have become a standard approach for diagnostic and therapeutic procedures in many surgical disciplines. Recent progress in endoscopic surgery is based on the integration of computer-enhanced telemanipulation systems. Because robot-assisted radical prostatectomies take up to 10 hours, the present study was performed to evaluate the effects of prolonged intraperitoneal CO2 insufflation on hemodynamics and gas exchange in 15 patients with prostate cancer. When CO2 insufflation was initiated, peak inspiratory pressure increased and reached significant values after a 1.5-hour period of intraperitoneal CO2 insufflation. With the release of CO2, peak inspiratory pressure decreased close to baseline values. A significant increase in heart rate was observed after a 4-hour period of increased intraabdominal pressure. Mean arterial blood pressure and central venous pressure remained stable during CO2 insufflation. Minute ventilation was adjusted according to repeated blood gas analyses to maintain pH, base excess (BE), bicarbonate (HCO3?), and PaCO2 within physiologic ranges. The present data show, that prolonged CO2 insufflation during totally endoscopic robot-assisted radical prostatectomy results in only minor changes in hemodynamics and acid-base status. Because of the limited experience with long-term pneumoperitoneum, we consider invasive haemodynamic monitoring and repeat blood gas analysis essential for such operations.

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.

Hepatic vascular response to elevated intraperitoneal pressure in the rat

The rat is increasingly being used to study the physiological response to elevated intra-abdominal pressure (IAP) during laparoscopic surgery. Although decreased portal venous flow associated with the elevated IAP has been reported in large animals, little information is available in rats. Furthermore, the relative blood flow changes in the hepatic artery and portal vein have not been reported. Therefore, this study was performed to elucidate the change in systemic and splanchnic circulation, including hepatic arterial and portal venular flow, during pneumoperitoneum in rats. Sprague-Dawley rats were assigned into either a ventilated or nonventilated group and then subjected to various levels of IAP (0, 5, 10, and 20 mm Hg) using carbon dioxide gas. At each pressure, both cardiac output and splanchnic organ flow were determined using fluorescent microspheres. There was no obvious hemodynamic difference between the ventilated and nonventilated groups. Mean arterial pressure and cardiac index were significantly lower with 20 mm Hg of IAP compared to 0 mm Hg in both groups. Flow to the spleen, stomach, duodenum, total intestine, and portal vein was all decreased by increasing IAP (P < 0.05 at 20 mm Hg compared to 0 mm Hg) and was significantly correlated to the decrease in cardiac index. However, the hepatic arterial flow was relatively preserved throughout all levels of IAP, suggesting activation of the hepatic arterial buffer response. We conclude that the decreased splanchnic flow during pneumoperitoneum largely depends on the decreased cardiac index. Hepatic artery flow, however, is selectively preserved and may provide protection for liver function during sustained elevations in IAP.

Reduction of CO(2)-pneumoperitoneum-induced metabolic hypoxaemia by the addition of small amounts of O(2) to the CO(2) in a rabbit ventilated model. A preliminary study

BACKGROUND

CO(2)-pneumoperitoneum used in endoscopic surgery induces system effects by CO(2) absorption. This study investigated the effect of the addition of O(2) to CO(2)-pneumoperitoneum, upon CO(2) absorption.

METHODS

The effect of a pneumoperitoneum using 100% CO(2) or 94% CO(2) + 6% O(2) upon arterial blood gases, acid base and O(2) homeostasis was evaluated. In series A suboptimal ventilation and a pneumoperitoneum pressure (PP) of 10 mmHg was used. In series B adequate ventilation and PP of 6 mmHg was used.

RESULTS

CO(2)-pneumoperitoneum profoundly affected blood gases and acid base homeostasis i.e. increasing pCO(2), HCO(3)(P < 0.001) and lactate concentrations (P < 0.05) and decreasing pH, actual base excess and standard bicarbonate (P < 0.001), resulting in metabolic hypoxaemia with desaturation, lower pO(2) (P < 0.001) and O(2)Hb (P < 0.05). These effects were more pronounced with higher PP and suboptimal ventilation.

CONCLUSION

CO(2)-pneumoperitoneum profoundly affected blood gases and acid base homeostasis resulting in metabolic hypoxaemia. The addition of 6% of O(2) to the CO(2)-pneumoperitoneum prevented these effects to a large extent. If these preliminary data are confirmed in the human, the addition of a few percent of O(2) to CO(2) could become important for endoscopic surgery of long duration, especially in obese patients with limited cardiorespiratory adaptation and steep Trendelenburg.

Metabolic and hemodynamic effects of CO2 pneumoperitoneum in a controlled hemorrhage model

BACKGROUND

Intracavity infusion of fibrin sealant-based agents, as a novel modality to control internal bleeding, is associated with an increase of pneumoperitoneum (PP) pressure. The safe limit of such increase has not been well defined in hypovolemic subjects. The purpose of this study was to evaluate the hemodynamic and metabolic effects of increasing PP pressure and to define the limits of carbon dioxide (CO2) insufflation in a controlled hemorrhage rat model.

METHODS

Ninety male rats (474 +/- 6 g, 37 degrees +/- 1 degrees C) were anesthetized, and mechanically ventilated. Animals were randomly distributed among 14 groups (n = 6-8) with an increasing amount of blood loss (0, 10, 15, and 17.5 mL/kg) and 15 minutes of CO2 insufflation at 0, 5, 10, and 15 mm Hg starting 15 minutes after hemorrhage, followed by desufflation. Mean arterial pressure (MAP), heart rate, and survival were recorded and arterial and venous blood samples were collected at baseline, at 15 minutes after hemorrhage, after insufflation, and after desufflation procedures to determine arterial blood gases and lactic acid levels.

RESULTS

In nonhemorrhaged animals, increasing PP pressure up to 15 mm Hg produced only transient changes in MAP and no increase in lactate level. A moderate hemorrhage (10 mL/kg) limited the safe abdominal pressure to 10 mm Hg with metabolic changes that were restored 15 minutes after desufflation. Higher PP pressure (15 mm Hg) at this hemorrhage level produced a significant decline in MAP (42%, p < 0.001) and progressive metabolic acidosis with a 2.1-fold increase (p < 0.01) in lactate level. The more severe hemorrhage (15 mL/kg) further reduced the limits of PP pressure such that 10 and 15 mm Hg resulted in a progressive decline of blood pressures (52% and 54%, respectively; p < 0.001) and severe metabolic acidosis as manifested by 3.3- and 3.1-fold rises in lactate levels, respectively. In the most severe hemorrhaged animals (17.5 mL/kg), the 50% mortality was primarily determined by the severity of the blood loss and the additional PP at 5 mm Hg had no significant impact.

CONCLUSION

The safe limit of PP pressurization with CO2 is dependent on the amount of blood loss. In this mechanically ventilated rat model, increasing the amount of blood loss from 0 to 15 mL/kg reduces the tolerable level of abdominal insufflation pressure from 15 mm Hg to 5 mm Hg. A 5-mm Hg PP pressure appears safe even in the most severely hemorrhaged animals.

Gastric air tonometry during laparoscopic cholecystectomy: a comparison of two PaCO2 levels

PURPOSE

Pneumoperitoneum can cause disturbances in acid-base balance and splanchnic perfusion. We studied the effect of ventilation on acid-base balance and gastric mucosal tonometric values in patients undergoing laparoscopic cholecystectomy.

METHODS

Twenty-four patients (ASA I-II) were randomly allocated into two groups. In the fixed ventilation group, ventilation was constant allowing free increase in PCO2, while in the constant CO2 group end-tidal PCO2 was fixed with ventilatory adjustment. Intraabdominal pressure was limited to 12 mmHg. Arterial acid-base balance, automated air tonometric variables and gastric mucosal to arterial PCO2 gap were determined frequently from anesthesia induction until three hours postoperatively.

RESULTS

During pneumoperitoneum, in the fixed ventilation group arterial PCO2 changed from 5.0 +/- 0.2 to 6.6 +/- 0.4 kPa and pH from 7.43 +/- 0.03 to 7.33 +/- 0.04, tonometric PCO2 from 5.1 +/- 0.5 to 6.9 +/- 0.4 and pH from 7.44 +/- 0.04 to 7.33 +/- 0.04. In the constant CO2 group these variables remained at control levels (P < 0.01 between groups). The PCO2 gap remained unchanged without any differences between the groups. In the recovery room all measured variables were within normal range in both groups.

CONCLUSION

Despite inter-group differences in arterial and tonometric PCO2 and pH values during CO2 pneumoperitoneum, the patients did not develop splanchnic hypoperfusion detectable by air tonometric method, as indicated by normal PCO2 gap in both groups throughout the study.

Simplified laparoscopic approach to "second-look" laparotomy: a review

Acute mesenteric vascular accidents are being diagnosed more commonly as a consequence of an aging population and often result in emergency bowel resection for ischemia. Because predicting postoperative intestinal viability remains difficult, second-look laparotomy has been advocated to improve outcomes. Recently, laparoscopy has emerged as an alternative to laparotomy for the diagnosis and treatment of ongoing postoperative ischemia. A review of the literature since 1994 reveals that, to date, 19 procedures have been reported to prevent 13 (68%) unnecessary laparotomies. We describe our laparoscopic second- look technique and review the literature. Second-look laparoscopy has been shown repeatedly to be a safe alternative to laparotomy. It is simple and reduces negative second-look laparotomy in critically ill patients.

Pneumoperitoneum secondary to endoscopic harvest of saphenous vein graft

Endoscopic harvest of saphenous vein graft for coronary artery bypass grafting decreases leg wound complications compared with traditional longitudinal incision. A case of pneumoperitoneum secondary to endoscopic harvest of saphenous vein using insufflation of carbon dioxide is reported. Hypercarbia, increased peak airway pressure, but no significant changes of hemodynamics, or myocardial ischemia were noted. The management of this rare complication is described.

Laparoscopic aortofemoral bypass grafting: human cadaveric and initial clinical experiences

PURPOSE

Postoperative complications are mainly related to the surgical trauma derived from the extensive abdominal incision and dissection after a conventional aortofemoral bypass grafting procedure. In an attempt to reduce postoperative complications, a concept of video-endoscopic vascular surgery on the infrarenal aortoiliac artery has been developed. On the basis of our experience with the practicability of video-endoscopic vascular surgery in the pelvic region in an animal study and in a pilot study of human cadavers, the purpose of this report was to describe three different methods that we evaluated on human cadavers and that we partly applied to patients.

METHODS

In this experimental study, three different approaches were used to perform video-endoscopic aortofemoral bypass grafting. We performed an observational trial on human corpses (n = 24) with the transabdominal-retroperitoneal approach (TARA), the extraperitoneal approach (EPA), and the transabdominal left paracolic approach (TAPA). The EPA also was applied to patients with aortoiliac occlusive diseases.

RESULTS

The TARA on cadavers (n = 4) soon was abandoned because it caused a burdensome sliding of the intestine into the operative field adjacent to the renal vessels, particularly in cases with obese subjects. In comparison, the TAPA (n = 6) with right-sided positioning of the patient retained the intestine in the right upper abdomen throughout the procedure. Until a surgeon actually is acquainted with the anatomic landmarks and the laparoscopic preparation technique, the EPA (n = 14) is a challenging procedure that necessitates thorough training. As with the TAPA, the EPA represents a procedure that reveals constant exposure of the operating field, even in cases with obese subjects. In the clinical observational study (n = 7), aortobifemoral bypass grafting was achieved totally laparoscopically with the EPA. The mean operating time was 6.5 hours and ranged from 3 to 10 hours. Blood transfusions were necessary after surgery in three patients (range, 1 to 3 red packed blood cells). One patient, who had had occlusion of the inferior mesenteric artery, died of ischemic colitis at postoperative day 10. The other patients had uneventful postoperative courses with minor wound discomfort.

CONCLUSION

Laparoscopic vascular surgery seems to be a promising procedure to minimize postoperative complications. On the basis of our experience, we do not favor the TARA. Because it necessitates steep Trendelenburg positioning to displace intra-abdominal organs, the TARA is not an appropriate approach, particularly in obese and cardiopulmonary frail cases. Contrarily, the TAPA and the EPA deliver potentially better results in terms of exposing the operative field and thus reducing operating time and perioperative morbidity rates. A prospective cadaveric and clinical trial may be justified to further evaluate the use of these surgical techniques.