Major Upper Abdominal Surgery Research Articles

Circulating-water garment or the combination of a circulating-water mattress and forced-air cover to maintain core temperature during major upper-abdominal surgery

BackgroundA recent heat-balance study in volunteers suggested that greater efficacy of circulating-water garments (CWGs) results largely from increased heat transfer across the posterior skin surface since heat transfer across the anterior skin surface was similar with circulating-water and forced-air. We thus tested the hypothesis that the combination of a circulating-water mattress (CWM) and forced-air warming prevents core temperature reduction during major abdominal surgery no worse than a CWG does. MethodsFifty adult patients aged between 18 and 85 yr old, undergoing major abdominal surgery, were randomly assigned to intraoperative warming with a combination of forced-air and a CWM or with a CWG (Allon ThermoWrap). Core temperature was measured in the distal oesophagus. Non-inferiority of the CWM to the CWG on change from baseline to median intraoperative temperature was assessed using a one-tailed Student’s t-test with an equivalency buffer of −0.5°C. ResultsData analysis was restricted to 16 CWG and 20 CWM patients who completed the protocol. Core temperature increased in both groups during the initial hours of surgery. We had sufficient evidence (P=0.001), to conclude that the combination of a CWM and forced-air warming was non-inferior to a CWG in preventing temperature reduction, with mean (95% CI) difference in the temperature change between the CWM and the CWG groups (CWM−CWG) of 0.46°C (−0.09°C, 1.00°C). ConclusionsThe combination of a CWM and forced-air warming is significantly non-inferior in maintaining intraoperative core temperature than a CWG.Trial registry: This trial has been registered at clinical trials.gov, identifier: NCT 00651898.

A randomized study of the serum pharmacokinetics of lower thoracic extended-release epidural morphine (DepoDur®) after lidocaine-epinephrine test dose administration in patients undergoing upper abdominal surgery

The primary objective was to evaluate the serum pharmacokinetic profile of a single 15-mg dose of extended-release epidural morphine (EREM) administered at the lower thoracic epidural space alone or following a lidocaine-epinephrine test dose in patients undergoing major upper abdominal surgery. This randomized, open-label study recruited men and women > or = 18 years of age scheduled for major upper abdominal surgery. Patients were randomly assigned to 1 of 5 treatment groups and were administered a single 15-mg dose of EREM or EREM preceded by a 3 ml lidocaine (1.5%)/epinephrine (1 : 200,000) test dose with or without a saline flush: EREM alone; test dose + flush + 3-minute wait + EREM; test dose + flush + 10-minute wait + EREM; test dose + flush + 15-minute wait + EREM; or test dose + 3-minute wait + EREM. EREM was administered at the lower thoracic epidural intervertebral space (T8 - T12) approximately 30 minutes before the surgical incision. Noncompartmental pharmacokinetic parameters were determined based on the serum concentration-time profiles of morphine and morphine metabolites. Effectiveness and safety were also assessed. The intent-to-treat and safety populations included 39 patients; the pharmacokinetic population included 37 patients. Administration of EREM 3 minutes after a lidocaine-epinephrine test dose, with or without a flush, resulted in an increased mean maximum serum concentration of morphine (Cmax; flush, 30.2 +/- 8.5 ng/ml; no flush, 25.6 +/- 10.1 ng/ml; EREM alone, 11.5 +/- 7.3 ng/ml) and a decreased median time to Cmax (tmax; flush, 0.2 h; no flush, 0.2 h; EREM alone, 2.0 h) compared with administration of EREM alone, without affecting relative morphine bioavailability. Flushing the catheter and waiting 15 minutes normalized the Cmax (11.4 +/- 6.4 ng/ml) but not the median tmax (0.5 h). There were no significant group differences in safety, tolerability, or analgesic effectiveness. The interaction between EREM and a lidocaine-epinephrine test dose administered at T8 - T12 can be minimized by waiting 15 minutes after test dose administration. The overall safety and effectiveness of 15 mg EREM administered at the lower thoracic epidural intervertebral space in patients undergoing major upper abdominal surgery appears similar to that observed in previous studies assessing lumbar administration. ClinicalTrials.gov Identifier: NCT00728832.

Short chain fatty acids exchange across the gut and liver in humans measured at surgery

Short chain fatty acids (SCFAs; acetate, propionate and butyrate) are important energy sources for colonocytes and are assumed to play a key role in gut health. Local effects of SCFAs have been investigated, but less is known about whole body metabolism of these SCFAs. The aim of the present study was to quantify the role of the gut and liver in interorgan exchange of SCFAs in humans in vivo. Twenty-two patients undergoing major upper abdominal surgery were studied. Blood was sampled from a radial artery, the portal and a hepatic vein. Portal, splanchnic and arterial blood flow was measured using intra-operative Duplex ultrasonography. SCFAs were measured on a liquid chromatography system combined with mass spectrometry. SCFAs were released by the gut, 34.9 (9.1) micromol kg bodyweight(-1)h(-1). SCFAs uptake by the liver was significant for propionate and butyrate; -5.6 (1.3) and -3.8 (1.6) micromol kg bodyweight(-1)h(-1) (p=0.0002 and p=0.03) respectively and counterbalanced gut release. Liver uptake of acetate was not significant, -5.2 (6.6) micromol kg bodyweight(-1)h(-1) (p=0.434). Splanchnic (i.e., gut+liver) SCFAs release was significant for acetate and propionate, 17.3 (7.3) and 1.2 (0.4) micromol kg bodyweight(-1)h(-1) (p=0.027 and p=0.0038), respectively. Splanchnic release of butyrate was not significantly different from zero (1.9 (1.2) micromol kg bodyweight(-1)h(-1), p=0.129). BMI and previous colonic resection did not affect gut release of SCFAs. This is the first in vivo study on the role of the gut and liver in SCFAs exchange in humans in vivo. It is shown that intestinal SCFAs release by the gut is equalled by hepatic uptake.

Epidural Ropivacaine Concentrations for Intraoperative Analgesia During Major Upper Abdominal Surgery: A Prospective, Randomized, Double-Blinded, Placebo-Controlled Study

The postoperative beneficial effects of thoracic epidural analgesia (TEA) within various clinical pathways are well documented. However, intraoperative data are lacking on the effect of different epidurally administered concentrations of local anesthetics on inhaled anesthetic, fluid and vasopressor requirement, and hemodynamic changes. We performed this study among patients undergoing major upper abdominal surgery under combined TEA and general anesthesia. Forty-five patients undergoing major upper abdominal surgery were randomly assigned to one of three treatment groups receiving intraoperative TEA with either 10 mL of 0.5% (Group 1) or 0.2% (Group 2) ropivacaine (both with 0.5 microg/mL sufentanil supplement), or 10 mL saline (Group 3) every 60 min. Anesthesia was maintained with desflurane in nitrous oxide (60%) initiated at an age-adapted 1 minimum alveolar concentration (MAC) until incision. Desflurane administration was then titrated to maintain an anesthetic level between 50 and 55, as assessed by continuous Bispectral Index monitoring and the common clinical signs (PRST score). Lack of intraoperative analgesia, as defined by an increase in pulse rate, sweating, and tearing (PRST) score >2 or an increase of mean arterial blood pressure (MAP) >20% of baseline, was treated by readjusting the end-tidal concentration of desflurane toward 1 MAC, and above this level by additional rescue i.v. remifentanil infusion. Hypotension, as defined as a decrease in MAP >20% of baseline, was treated by reducing the end-tidal desflurane concentration to a Bispectral Index level of 50-55 and below that with crystalloid or norepinephrine infusion, depending on central venous pressure. End-tidal desflurane concentration could be significantly reduced in Group 1 to 0.7 +/- 0.1 MAC (P < 0.001) and to 0.8 +/- 0.1 MAC (P < 0.001) in Group 2, but not in Group 3. Significant hypotension occurred within 20 min in all patients of Groups 1 and 2 (MAP from 80 +/- 10 to 56 +/- 5) (Group 1), 78 +/- 18 to 58 +/- 7 mm Hg (Group 2), P < 0.01, whereas MAP remained unchanged in Group 3 (74 +/- 12 to 83 +/- 15 mm Hg, P = 0.42). Heart rate did not change significantly over time within any of the groups. Furthermore, groups did not differ significantly regarding i.v. fluid and norepinephrine requirement. Patients in Group 3 received more remifentanil throughout the surgical procedure (7.2 +/- 4.9 mg x kg(-1) x h(-1)) when compared with Group 2 (1.6 +/- 2.2 mg x kg(-1) x h(-1)), P < 0.01. Remifentanil infusion among patients receiving ropivacaine 0.5% was not necessary at any time. Epidural administration of 0.5% ropivacaine leads to a more pronounced sparing effect on desflurane concentration for an adequate anesthetic depth when compared with a 0.2% concentration of ropivacaine at comparable levels of vasopressor support and i.v. fluid requirement.

Appropriate Nutritional Support for Patients Undergoing Major Upper Abdominal Surgery

Annals of Surgery: March 2009 - Volume 249 - Issue 3 - p 543-544 doi: 10.1097/SLA.0b013e31819aad99

Appropriate Nutritional Support for Patients Undergoing Major Upper Abdominal Surgery

Appropriate Nutritional Support for Patients Undergoing Major Upper Abdominal Surgery

Evaluation of abdominal binder after major upper gastrointestinal surgery

The aim of the study was to evaluate the use of an elastic abdominal binder after open major upper abdominal surgery. In the trial, 50 patients undergoing major upper abdominal surgery were include...

Postoperative ileus—an update on preventive techniques

This article reviews techniques currently used to prevent or reduce the duration of postoperative ileus (POI), which is considered an undesirable stress response to major abdominal surgery that leads to discomfort, morbidity and prolonged hospital stay. In several randomized studies, a number of techniques have been demonstrated to reduce the occurrence and/or duration of POI: thoracic epidural analgesia with local anesthetics, peripheral opioid antagonists, laxatives, chewing gum, intravenous and incisional local anesthetics, and avoidance of routine nasogastric intubation and fluid excess. Early institution of oral feeding and laparoscopic surgery might also be effective, but there is less clear evidence available to support their use. When some of these techniques are combined as part of the concept of multimodal postoperative rehabilitation (fast-track surgery), the duration of POI after open or laparoscopic abdominal surgery can be reduced to 24-48 h in most patients. There is a need for data on the effect of these techniques on POI when applied to major upper abdominal surgeries and emergency abdominal operations (e.g. trauma, peritonitis, etc.).

Evaluation of the stability and safety of Venolipid MCT/LCT 20% administered by an all-in-one system in patients after major gastrointestinal surgery

Summary Background & aims A structured fat emulsion containing 50% medium-chain triglycerides (MCTs) is used for total parenteral nutrition for surgical patients. Due to stability and safety considerations, it is commonly infused separately from dextrose solution, increasing cost and risk of contamination. We evaluated the physiochemical stability and clinical safety of an all-in-one admixture. Methods The physiochemical stability of an all-in-one admixture containing 20% medium- and long-chain triglycerides (Venolipid MCT/LCT 20%), dextrose, amino acids, electrolytes, trace elements and vitamins was compared to a two-in-one system. Solutions were stored at 4 °C for 1 week; appearance, pH, osmolality and particle size and distribution were analyzed at room temperature on days 1, 4 and 7. Clinical safety of the all-in-one admixture versus use of separate systems was determined in patients after major upper abdominal surgery in a prospective, randomized, controlled study (total n = 30). Results During storage, the all-in-one admixture maintained its colour. No precipitation, flocculation or creaming was observed. The pH and average particle size did not change significantly. There were no adverse clinical events related to the all-in-one admixture after continuous infusion for 5 days. Conclusion The all-in-one admixture containing Venolipid MCT/LCT 20% can be stored at 4 °C for 1 week and safely used in patients after major upper abdominal surgery.

Lung function after major upper abdominal surgery in patients with mild to moderate COPD: A randomized comparison between repeat boluses of epidural morphine/ropivacaine and a P.C.E.A for postoperative analgesia

Lung function after major upper abdominal surgery in patients with mild to moderate COPD: A randomized comparison between repeat boluses of epidural morphine/ropivacaine and a P.C.E.A for postoperative analgesia

Combined spinal – epidural anesthesia in major abdominal surgery in high‐risk neonates and infants

Combined spinal-epidural anesthesia (CSE-A) is reportedly safe and effective for the pediatric population in infraumbilical surgery. Our main purpose was to describe our experience of this technique in neonates and infants undergoing elective major upper abdominal surgery. Spinal anesthesia was performed in 28 neonates and infants with isobaric bupivacaine 0.5%, 1 mg.kg(-1) followed by placement of a caudal epidural catheter to thoracic spinal segments. The catheter tip position was confirmed radiographically. Respiratory and hemodynamic data were collected before and after the CSE-A and throughout the operation, as a measure of anesthetic effectiveness. Complications related to the anesthesia technique were collected as a measure of the anesthetic technique safety. Satisfactory surgical anesthesia was achieved in 24 neonates and infants, four patients were converted to general anesthesia. Respiratory and hemodynamic variables did not change significantly during surgery, compared with baseline values: oxygen saturation (P = 0.07), systolic and diastolic blood pressures (P = 0.143, P = 0.198 respectively), heart rate (P = 0.080) and respiratory rate (P = 0.127). However, twenty infants were fussy during the surgical procedures and were calmed with intravenous midazolam; our patients required oxygen supplementation and transient manual ventilation intraoperatively. Combined spinal-epidural anesthesia could be considered as an effective anesthetic technique for elective major upper abdominal surgery in awake or sedated neonates and infants, and could be used cautiously by a pediatric anesthesiologist as an alternate to general anesthesia in high-risk neonates and infants undergoing upper gastrointestinal surgery.

Percutaneous Transhepatic Cholangiodrainage as Rescue Therapy for Symptomatic Biliary Leakage Without Biliary Tract Dilation After Major Surgery

Symptomatic biliary leakage following major upper abdominal surgery is a severe complication resulting in increased morbidity and mortality. Treatment options usually include either endoscopic intervention or surgical revision. These options may be burdened by a high perioperative risk for the patient (e.g., patients with severe disease) or simply may not be possible (e.g., nonpreserved gastroduodenal passage). In the past, percutaneous transhepatic cholangiodrainage did only seem to be a viable option for patients with dilated bile ducts. Here, we present our experience in a consecutive series of patients with symptomatic biliary leakage following major upper abdominal surgery and without dilation of the biliary system that underwent percutaneous transhepatic cholangiodrainage. Percutaneous transhepatic cholangiodrainage was feasible in 15 of 18 patients (83.3%). The procedure was technically not possible in three patients (16.7%). In 10 of the 15 patients (66.6%) with feasible percutaneous transhepatic cholangiodrainage, biliary leakage was definitely controlled without the need for surgical revision. Depending on the experience with the interventional procedure, percutaneous transhepatic cholangiodrainage should be considered as an alternative for treatment of symptomatic biliary leakage instead of immediate reoperation.

The Cardiovascular Effects of Thoracic Epidural Injection of Ropivacaine during Sevoflurane General Anesthesia

Background: Thoracic epidural anesthesia (TEA) combined with general anesthesia is commonly used in major upper abdominal surgery. The advantages of this method is the suppression of the perioperative stress response, the improvement in endocardial perfusion, and the reduction of myocardial oxygen consumption, postoperative morbidity and mortality. In particular, this method reduces the level of postoperative ileus and intestinal anastomosis leakage during gastrointestinal surgery. However, there is the possibility of severe cardiovascular depression using this combination method. This study evaluates the cardiovascular effects of extensive TEA combined with sevoflurane general anesthesia. Methods: Fifty patients scheduled subtotal gastrectomy were enrolled in this study. After administering a bolus injection of 20 ml of 0.375% ropivacaine through an epidural catheter during sevoflurane general anesthesia, mean arterial pressure, heart rate, stroke volume, cardiac output, and systemic vascular resistance measured by Hemosonic (HemoSonicTM 100, Arrow, USA) every 5 minutes over a 30-minute period after the injection. Results: All the data showed a significant decrease from 5 minutes after the epidural bolus injection except for the stroke volume, but that was not important clinically. Conclusions: A thoracic epidural injection of 20 ml of 0.375% ropivacaine can be used safely during sevoflurane anesthesia without severe cardiovascular complications during upper abdominal surgery.

Peritoneal cytokines are associated with reports of fatigue following major abdominal surgery

Study Objective: To evaluate the influence of major abdominal surgery on the plasma levels of inflammatory cytokines interleukin-6 (IL-6), interleukin-8 (IL-8) and granulocyte colony-stimulating factor (G-CSF).Design: Prospective study.Setting: University hospital.Patients: 10 ASA physical status I and II patients undergoing upper abdominal surgery.Interventions: All patients received combined general-epidural anesthesia with isoflurane and nitrous oxide, after insertion of an epidural catheter at T7-T9 dosed with 1.5% lidocaine.Measurements and Main Results: Plasma cytokine (IL-6, IL-8, G-CSF) levels were determined with an enzyme-linked immunosorbent assay (ELISA) at pre-anesthesia, 0, 2, and 4 hours during surgery, and at the end of surgery, followed by sampling on the morning of postoperative days 1 (POD1) and 3 (POD3). Plasma cortisol levels were also determined. The plasma levels of IL-6 increased gradually after skin incision and reached the maximal value at the end of surgery (p < 0.001). IL-8 levels also increased from the baseline value to their maximum at the end of surgery (p < 0.05). G-CSF levels were elevated from the pre-anesthesia value to their maximum by the end of operation (p < 0.005). Plasma cortisol levels were increased after skin incision (p < 0.001). Postoperative cytokine levels correlated significantly with each other (r = 0.68, p < 0.05 for IL-6 vs. IL-8; r = 0.81, p < 0.005 for IL-6 vs. G-CSF; and r = 0.84, p < 0.005 for IL-8 vs. G-CSF). Postoperative IL-6 levels and intraoperative blood loss correlated significantly (r = 0.64, p < 0.05).Conclusions: These results suggest that major upper abdominal surgery stimulates the release of inflammatory cytokines presumably from the operation site. Further study is warranted to evaluate the modulation of inflammatory responses in the perioperative period.

Postoperative Pain Relief After Hepatic Resection in Cirrhotic Patients: The Efficacy of a Single Small Dose of Ketamine Plus Morphine Epidurally

In cirrhotic patients undergoing hepatic surgery, postoperative analgesia remains a challenge. In this study, we evaluated the efficacy of a single dose of morphine combined with small-dose ketamine given epidurally for postoperative pain relief. One-hundred-four classification “Child A” cirrhotic patients were randomly assigned to two groups: 1) (MKG, n = 54): epidural morphine (3.5–5 mg) plus ketamine (20/30 mg); and 2) epidural morphine (3.5/5 mg) (MG, n = 50). The level of analgesia, side effects, psychomimetic and neurological disorders, additional analgesic needs, and overall quality of the analgesia were recorded. The mean duration of analgesia was longer in the MKG group (27.2 ± 8 h versus 16.4 ± 10 h;P < 0.05). In the MKG group, the visual analog scale (VAS) score began to be significantly lower from 14 h at rest and 12 h on coughing until the end of the study. The need for additional analgesia was also smaller in the MKG group (P < 0.05): at 24 h, only 10% of patients in the MKG group needed complementary analgesia, whereas in the MG group it was 100% (P = 0.003). Side effects were similar in both groups. Psychomimetic side effects and neurological disorders were not detected. These results suggest that postoperative analgesia provided by a single dose of epidural morphine with small-dose ketamine is effective in cirrhotic Child’s A patients having major upper abdominal surgery.

Multimodal analgesia and intravenous nutrition preserves total body protein following major upper gastrointestinal surgery

Background and Objectives: This study examined whether perioperative multimodal analgesia (MMA) improves the effectiveness of intravenous nutrition (IVN) as a means of preventing protein wasting following major upper abdominal surgery (UAS). The MMA regimen utilized combined epidural opioid/local anesthetic and the systemic nonsteroidal anti-inflammatory drug (NSAID) ketorolac for 48 hours. Methods: In a prospective, randomized, nonblinded study, 47 patients scheduled for major UAS were allocated to receive the following: MMA [plusmn] intravenous lipid-based nutrition (IVN) or patient-controlled analgesia with opioids (PCA) [plusmn] IVN. Pain scores, nitrogen balance, total body protein (TBP), arterial blood gases, and various hormones were measured. Results: Pain control was significantly better in the MMA patients at rest and coughing. Only the MMA + IVN group maintained TBP, mean ([plusmn]95% confidence interval) preoperative day 1, 10.5 ([plusmn]1.0) kg; day 14, 10.7 ([plusmn]1.2) kg, whereas TBP decreased in the other groups (P = .04). Nitrogen balance was significantly greater in patients receiving IVN on day 7 (P = .01), but there was no effect related to the analgetic regimen. Decreased PaO2 seen on postoperative day 2 was not prevented by MMA. The hormonal response to surgery was not influenced by treatment modality, apart from a return to postprandial insulin levels on postoperative day 7 in those patients receiving IVN (P = .002). Conclusions: In conclusion, we have shown that the combination of MMA and IVN prevents protein loss and improves pain control after major UAS. Our results suggest that after UAS, MMA significantly reduced pain and, in combination with IVN, preserves total body protein and fat. This is the first direct evidence of such effects associated with a commonly used multimodal regimen. Reg Anesth Pain Med 2002;27:15-22.

Patient‐controlled pethidine after major upper abdominal surgery: comparison of the epidural and intravenous routes*†

We compared epidural (n = 17) and intravenous (n = 20) patient‐controlled analgesia (PCA) using pethidine (bolus 10 mg, lockout interval 10 min, 4‐h maximum dose 3 mg.kg−1) after total gastrectomy. We found that mean (SD) pethidine consumption in the first 24 h was 33% less in the epidural group [255 (85) mg] than in the intravenous group [379 (129) mg, p = 0.002], although most of this difference occurred in the first 8 h. Plasma concentrations of pethidine were lower at 8 h (p &lt; 0.01) in the epidural group, but were similar at 24 h. Pain scores, side‐effects, patient satisfaction and patient outcome were similar between groups. Epidural and intravenous pethidine PCA provided similar efficacy after major abdominal surgery, although the epidural route can reduce the amount of pethidine used initially.

Evaluation of the safety and efficacy of epidural ketamine combined with morphine for postoperative analgesia after major upper abdominal surgery

Study Objective: To evaluate the efficacy of the combination of epidural ketamine and morphine compared with epidural morphine alone for postoperative pain relief following major upper abdominal surgery. Study design: Prospective, randomized, double-blinded study. Setting: Tertiary care referral and teaching hospital Patients: 46 ASA physical status I and II patients who underwent major upper abdominal procedures. Interventions: Patients were randomly allocated to one of the two treatment groups: patients in Group 1 received epidural morphine 50 μg/kg whereas patients in Group 2 received epidural ketamine 1 mg/kg combined with 50 μg/kg of morphine postoperatively. Measurements: A blinded observer using a visual analog scale (VAS) for pain assessment followed up patients for 48 hours postoperatively. Top-up dose of epidural morphine was provided when VAS was higher than 4. Analgesic requirements and side effects were compared between the two groups. Results: Only 40 patients completed the study. There were no differences between the two groups with respect to age, gender, weight, duration, or type of surgical procedure or intraoperative opioid requirements. Onset of analgesia was faster (p < 0.001) in Group 2 (11 min) than in Group 1 patients (25 min). The time for first requirement of analgesia was significantly (p < 0.01) longer (19.8 ± 9.8 hours) in Group 2 patients than Group 1 (12.8 ± 6.2 hours). Total number of supplemental doses of epidural morphine required in the first 48 hours postoperatively was also significantly less (p < 0.005) in Group 2 compared to Group 1. Patients in Group 2 had higher sedation scores than Group I patients for the first 2 hours postoperatively. None of the patients in either group developed hallucinations or respiratory depression. Other side effects such as pruritus, nausea, and vomiting were also similar in both groups. Conclusions: The addition of epidural ketamine 1 mg/kg to morphine 50 μg/kg improved analgesia after major upper abdominal surgery without increasing side effects.

Splanchnic circulation and regional sympathetic outflow during peroperative PEEP ventilation in humans

The splanchnic organs represent a major target for sympathetic outflow and an important region for haemodynamic effects on cardiovascular homeostasis. We have studied regional haemodynamic and sympathetic changes in the splanchnic bed during standardized circulatory stress from positive end-expiratory pressure ventilation (PEEP). We investigated eight patients undergoing major upper abdominal surgery using a radiotracer method to measure plasma spillover of norepinephrine as an index of sympathetic nerve activity using arterial, portal and hepatic venous blood sampling. Mesenteric and hepatic perfusion were measured by ultrasound transit time flowmetry and blood-gas analyses. Steady state measurements were performed before and during PEEP ventilation at 10 cm H2O. Plasma spillover of norepinephrine in the mesenteric and hepatic organs represented mean 49 (SEM 8)% and 7 (2)%, respectively, of systemic norepinephrine spillover at baseline, and PEEP ventilation did not cause any significant changes. However, PEEP ventilation significantly decreased portal venous blood flow while hepatic blood flow was preserved by a compensatory increase in hepatic arterial blood flow. Mesenteric and hepatic oxygen delivery changed according to blood flow, and there were no changes in regional oxygen consumption. Thus PEEP ventilation altered mesenteric and hepatic perfusion, independent of any change in corresponding sympathetic nerve activity. Regulation of hepatic blood supply, not related to sympathetic activity, maintained liver oxygenation during PEEP ventilation despite a simultaneous decrease in mesenteric perfusion.

Postoperative Analgesia by Continuous Extradural Infusion of Ropivacaine After Upper Abdominal Surgery

Comment: The authors adopted a different approach to traditional dose-response studies. Instead of using one concentration of ropivacaine and varying the infusion rate, they used differing concentrations of ropivacaine at the fixed rate of 10 mL/hr. With these methods, the authors demonstrated superior analgesia as measured by a visual analog scale for pain at rest and on coughing with the 0.2 and the 0.3% concentrations. The 0.3% concentration had the lowest intravenous morphine requirement during the study period. One of ten patients in each of the 0.2 and 0.3% groups developed motor block, whereas no motor block occurred in the control or 0.1% infusion groups. The 0.2 and the 0.3% concentrations were also associated with a higher incidence of hypotension that was easily treated with an increase in the intravenous infusion rate. Thus, the 0.3% concentration seems to be the best epidural solution for the immediate 24-hr postoperative period in terms of achieving analgesia after major upper abdominal surgery without the addition of neuraxial opioids. One major risk following abdominal surgery is pulmonary infection.1 Coughing and deep breathing are important to prevent both atelectasis and infection. The benefit of decreased pain with coughing outweighs the small risk of minor hypotension. Furthermore, patients will not be ambulating during the first 24-hr period. It would be interesting to extend this study beyond the 24-hr period to determine whether there would be any benefit to then switching to the lower concentrations.