Enhanced Recovery After Surgery (ERAS) for gastrointestinal surgery, part 2: consensus statement for anaesthesia practice

Background

The present interdisciplinary consensus review proposes clinical considerations and recommendations for anaesthetic practice in patients undergoing gastrointestinal surgery with an Enhanced Recovery after Surgery (ERAS) programme.

Methods

Studies were selected with particular attention being paid to meta‐analyses, randomized controlled trials and large prospective cohort studies. For each item of the perioperative treatment pathway, available English‐language literature was examined and reviewed. The group reached a consensus recommendation after critical appraisal of the literature.

Results

This consensus statement demonstrates that anaesthesiologists control several preoperative, intraoperative and postoperative ERAS elements. Further research is needed to verify the strength of these recommendations.

Conclusions

Based on the evidence available for each element of perioperative care pathways, the Enhanced Recovery After Surgery (ERAS ^®) Society presents a comprehensive consensus review, clinical considerations and recommendations for anaesthesia care in patients undergoing gastrointestinal surgery within an ERAS programme. This unified protocol facilitates involvement of anaesthesiologists in the implementation of the ERAS programmes and allows for comparison between centres and it eventually might facilitate the design of multi‐institutional prospective and adequately powered randomized trials.

Enhanced Recovery After Surgery (ERAS) for gastrointestinal surgery, part 1: pathophysiological considerations

BACKGROUND

The present article has been written to convey concepts of anaesthetic care within the context of an Enhanced Recovery After Surgery (ERAS) programme, thus aligning the practice of anaesthesia with the care delivered by the surgical team before, during and after surgery.

METHODS

The physiological principles supporting the implementation of the ERAS programmes in patients undergoing major abdominal procedures are reviewed using an updated literature search and discussed by a multidisciplinary group composed of anaesthesiologists and surgeons with the aim to improve perioperative care.

RESULTS

The pathophysiology of some key perioperative elements disturbing the homoeostatic mechanisms such as insulin resistance, ileus and pain is here discussed.

CONCLUSIONS

Evidence-based strategies aimed at controlling the disruption of homoeostasis need to be evaluated in the context of ERAS programmes. Anaesthesiologists could, therefore, play a crucial role in facilitating the recovery process.

Understanding the mechanisms by which isoflurane modifies the hyperglycemic response to surgery

We studied the effect of anesthesia on the kinetics of perioperative glucose metabolism by using stable isotope tracers. Twenty-three patients undergoing cystoprostatectomy were randomly assigned to receive epidural analgesia combined with general anesthesia (n = 8), fentanyl and midazolam anesthesia (n = 8), or inhaled anesthesia with isoflurane (n = 7). Whole-body glucose production and glucose clearance were measured before and during surgery. Glucose clearance significantly decreased during surgery independent of the type of anesthesia. Epidural analgesia caused a significant decrease in glucose production from 10.2 +/- 0.4 to 9.0 +/- 0.4 micromol. kg(-1). min(-1) (P < 0.05), whereas the plasma glucose concentration was not altered (before surgery, 5.0 +/- 0.2 mmol/L; during surgery, 5.2 +/- 0.1 mmol/L). Glucose production did not significantly change during fentanyl/midazolam anesthesia (before surgery, 10.5 +/- 0.5 micromol. kg(-1). min(-1); during surgery, 10.1 +/- 0.5 micromol. kg(-1). min(-1)), but plasma glucose concentration significantly increased from 4.8 +/- 0.1 mmol/L to 5.3 +/- 0.2 mmol/L during surgery (P < 0.05). Isoflurane anesthesia caused a significant increase in plasma glucose concentration (from 5.2 +/- 0.1 mmol/L to 7.2 +/- 0.5 mmol/L) and glucose production (from 10.8 +/- 0.5 micromol. kg(-1). min(-1) to 12.4 +/- 1.0 micromol. kg(-1). min(-1)) (P < 0.05). Epidural analgesia prevented the hyperglycemic response to surgery by a decrease in glucose production. The increased glucose plasma concentration during fentanyl/midazolam anesthesia was caused by a decrease in whole-body glucose clearance. The hyperglycemic response observed during isoflurane anesthesia was a consequence of both impaired glucose clearance and increased glucose production.

IMPLICATIONS

Epidural analgesia combined with general anesthesia prevented the hyperglycemic response to surgery by decreasing endogenous glucose production. The increased glucose plasma concentration in patients receiving fentanyl/midazolam anesthesia was caused by a decrease in whole-body glucose clearance. The hyperglycemic response observed during inhaled anesthesia with isoflurane was a consequence of both impaired glucose clearance and increased glucose production.

Airway topicalisation in morbidly obese patients using atomised lidocaine: 2% compared with 4%

We evaluated the technique of airway anaesthesia using atomised lidocaine for awake oral fibreoptic intubation in morbidly obese patients using two doses of local anaesthetic. Morbidly obese patients were allocated to receive either 2% or 4% lidocaine (40 ml) for oral airway anaesthesia using an atomiser with high oxygen flow. Patients were carefully sedated using midazolam and fentanyl. Outcomes included patient tolerance to airway manipulation, haemodynamic parameters, and serial plasma lidocaine concentrations. In all, 27 patients were enrolled in the study (2% cohort n = 14, 4% cohort n = 13). Patient characteristics and time for topicalisation and airway management were similar. Haemodynamic parameters did not change significantly. Tolerance to insertion of the Ovassapian airway, bronchoscopy, and tracheal tube positioning was excellent (12 vs 12 patients, 12 vs 12 patients, and 8 vs 12 patients had no response, respectively, 2% vs 4%). Differences did not reach statistical significance. Peak plasma lidocaine concentration was significantly lower in the 2% group (2.8 (0.8) microg.ml(-1) compared with 6.5 (1.0) microg.ml(-1), p < 0.05). Airway anaesthesia using atomised lidocaine for awake fibreoptic intubation in the morbidly obese is efficacious, rapid, and safe. Compared with 4% lidocaine, the 2% dose provides acceptable intubating conditions in most cases and produces lower plasma lidocaine levels.

Epidural blockade improves substrate utilization after surgery

The purpose of this study was to test the hypothesis that epidural blockade with local anesthetic improves the anticatabolic effects of glucose after colorectal surgery. Sixteen patients were randomly assigned to undergo a 6-h stable isotope infusion study (3 h fasted, 3 h glucose infusion at 4 mg. kg(-1). min(-1)) on the second postoperative day with or without perioperative epidural blockade. Protein synthesis, breakdown and oxidation, and glucose production and clearance were assessed by L-[1-(13)C]leucine and [6, 6-(2)H(2)]glucose. Epidural blockade did not affect protein and glucose metabolism in the fasted state. Glucose infusion increased glucose clearance (P < 0.05), accompanied by an increase in the respiratory quotient (P < 0.05) and a decrease in leucine oxidation (P < 0.05) only in the presence of epidural blockade. An inverse correlation (r = -0.74, P < 0.05) between changes in glucose clearance and leucine oxidation was observed. In conclusion, epidural blockade facilitates whole body glucose uptake and inhibits endogenous protein oxidation after abdominal surgery, indicating a shift from a protein to a more glucose-dominated substrate utilization.

Integrated analysis of protein and glucose metabolism during surgery: effects of anesthesia

The aim of this study was to assess dynamic changes in protein and glucose metabolism during surgery. Twelve patients undergoing colorectal surgery received either intravenous propofol anesthesia (n = 6) or inhalational anesthesia with desflurane (n = 6). Pre- and intraoperative protein and glucose kinetics were analyzed by an isotope dilution technique using L-[1-(13)C]leucine and [6,6-(2)H(2)]glucose. Plasma concentrations of glucose, lactate, free fatty acids, insulin, glucagon, and cortisol were measured before and after 2 h of surgery. The rates of appearance of leucine and glucose, leucine oxidation, protein synthesis, and glucose clearance decreased during surgery, independent of the type of anesthesia (P < 0.05). A correlation between the rate of appearance of leucine and glucose was observed (r = 0.755, P < 0.001). Intraoperative plasma cortisol and glucose concentrations increased (P < 0.05), whereas plasma concentrations of lactate, free fatty acids, insulin, and glucagon did not change. Surgery causes a depression of whole body protein and glucose metabolism, independent of the anesthetic technique. There is a correlation between perioperative glucose production and protein breakdown.

Low dose clonidine premedication accentuates the hyperglycemic response to surgery

PURPOSE

To investigate the influence of low dose clonidine premedication on perioperative glucose homeostasis.

METHODS

Sixteen patients undergoing abdominal hysterectomy for benign uterine myoma were randomly assigned to receive either iv clonidine (1 microg x kg(-1)) 30 min before induction of general anesthesia (clonidine, n=8) or saline (control, n=8). Plasma concentrations of glucose, insulin, cortisol, epinephrine and norepinephrine were measured before, during and two hours after surgery. At the same time heart rate, mean arterial pressure and cardiac output were recorded.

RESULTS

In both groups, glucose concentrations significantly increased during and after surgery. Intraoperative glucose plasma concentration in the clonidine group was higher than in the control group (clonidine: 6.8 +/- 0.6 mmol x L(-1) vs control: 5.7 +/- 0.8 mmol x L(-1), P < 0.05). This was accompanied by a lower insulin plasma concentration (clonidine: 3.9 +/- 1.9 microU x mL(-1) vs control: 6.5 +/- 2.8 microU x mL(-1), P <0.05). Heart rate, mean arterial pressure and cardiac output remained unchanged throughout the study period without any differences between the groups. While norepinephrine plasma concentrations increased in the control group only (P <0.05), the plasma concentrations of epinephrine and cortisol increased in both groups (P <0.05). Clonidine significantly attenuated the cortisol response as reflected by lower intra- and postoperative cortisol plasma concentrations than in the control group (P <0.05).

CONCLUSION

Premedication with clonidine 1 microg x kg(-1) accentuates the hyperglycemic response to lower abdominal surgery caused by the decrease in insulin plasma concentrations.

Sevoflurane versus isoflurane--anaesthesia for lower abdominal surgery. Effects on perioperative glucose metabolism

BACKGROUND

The aim of this study was to determine the impact of sevoflurane anaesthesia on metabolic and endocrine responses to lower abdominal surgery.

METHODS

A prospective randomized controlled study in 20 patients undergoing abdominal hysterectomy. Patients were randomly assigned to receive either sevoflurane (S) or isoflurane anaesthesia (I). Using a stable isotope dilution technique, endogenous glucose production (EGP) and plasma glucose clearance (GC) were determined pre- and postoperatively (6,6-2H2-glucose). Plasma concentrations of glucose, insulin, cortisol, epinephrine and norepinephrine were measured preoperatively, 5 min after induction of anaesthesia, during surgery and 2 h after the operation.

RESULTS

EGP increased in both groups with no intergroup differences (preop. S 12.2 +/- 1.6, I 12.4 +/- 1.6; postop. S 16.3 +/- 1.9*, I 19.0 +/- 3.1* micromol kg(-1) min(-1), all values are means +/- SD, *P < 0.05 vs. preop.). Plasma glucose concentration increased and GC decreased in both groups. There were no differences between groups. (Glucose conc. mmol l(-1) preop.: S 4.1 +/- 0.3, I 3.9 +/- 0.5; 5 AI S 5.1 +/- 0.6*, I 5.1 +/- 1.0*, postop. S 7.0 +/- 1.0*, I 7.1 +/- 1.4*; * = P < 0.05 vs. preop.; GC ml kg(-1)min(-1) preop. S 3.0 +/- 0.4, I 3.2 +/- 0.4; postop. S 2.4 +/- 0.3*, I 2.7 +/- 0.3*; *=P < 0.05 vs. preop.) Insulin plasma concentrations were unchanged. Cortisol plasma concentrations increased intra- and postoperatively with no changes between the groups. Norepinephrine plasma concentration increased in the S group after induction of anaesthesia. I group norepinephrine was increased 2 h after operation and showed no intergroup differences.

CONCLUSION

Sevoflurane, as well as isoflurane, does not prevent the metabolic endocrine responses to surgery.

The independent effect of propofol anesthesia on whole body protein metabolism in humans

BACKGROUND

The purpose of this study was to examine the effect of general anesthesia with propofol in the absence of surgical stimulation on whole body protein metabolism.

METHODS

Six unpremedicated patients were studied. General anesthesia included propofol (120 microg x kg(-1) x min(-1)), vecuronium bromide, and oxygen-enriched air. Changes in protein breakdown, protein oxidation, and synthesis were measured by an isotope dilution technique using a constant infusion of the stable isotope tracer L-[1-13C]leucine (0.008 mg x kg(-1) x min(-1)) before and during 100 min of propofol anesthesia. The plasma concentrations of glucose, lactate, non-esterified fatty acids, and cortisol were measured before and during anesthesia.

RESULTS

An isotopic steady state of plasma [1-13C]alpha-ketoisocaproate (taken to represent the intracellular leucine precursor pool enrichment for protein synthesis) and expired 13C-carbon dioxide were obtained before and during propofol infusion. Whole body protein breakdown decreased during propofol anesthesia by 6% (P < 0.05), whereas protein synthesis and oxidation did not change significantly. Plasma concentration of cortisol decreased after 90 min of propofol anesthesia (P < 0.05). No significant changes of plasma concentrations of glucose, lactate, and non-esterified fatty acids occurred during propofol administration.

CONCLUSIONS

Propofol anesthesia did not significantly affect whole body protein synthesis and oxidation but caused a small, although significant, decrease in whole body protein breakdown, possibly mediated through the suppression of plasma cortisol concentration.

Randomized clinical trial of the impact of insulin therapy on liver function in patients undergoing major liver resection

BACKGROUND

Postoperative liver dysfunction is the major source of morbidity and mortality in patients undergoing partial hepatectomy. This study tested the benefits of a metabolic support protocol based on insulin infusion, for reducing liver dysfunction following hepatic resection.

METHODS

Consecutive consenting patients scheduled for liver resection were randomized to receive preoperative dextrose infusion followed by insulin therapy using the hyperinsulinaemic normoglycaemic clamp protocol (n = 29) or standard therapy (control group, n = 27). Patients in the insulin therapy group followed a strict dietary regimen for 24 h before surgery. Intravenous dextrose was started at 2 mg per kg per min the night before and continued until surgery. Hyperinsulinaemic therapy for a total of 24 h was initiated at 2 munits per kg per min at induction of anaesthesia, and continued at 1 munit per kg per min after surgery. Normoglycaemia was maintained (3.5-6.0 mmol/l). Control subjects received no additional dietary supplement and a conventional insulin sliding scale during fasting. All patients were tested serially to evaluate liver function using the Schindl score. Liver tissue samples were collected at two time points during surgery to measure glycogen levels.

RESULTS

Demographics were similar in the two groups. More liver dysfunction occurred in the control cohort (liver dysfunction score range 0-8 versus 0-4 with insulin therapy; P = 0.031). Median (interquartile range) liver glycogen content was 278 (153-312) and 431 (334-459) µmol/g respectively (P = 0.011). The number of complications rose with increasing severity of postoperative liver dysfunction (P = 0.032) CONCLUSION: The glucose-insulin protocol reduced postoperative liver dysfunction and improved liver glycogen content.

REGISTRATION NUMBER

NCT00774098 (http://www.clinicaltrials.gov).

Randomized clinical trial of the anabolic effect of hypocaloric parenteral nutrition after abdominal surgery

BACKGROUND

The observed failure of hypocaloric nutrition to establish an anabolic state after surgery may reflect inadequate control for the type and quality of analgesia in the studies performed. This study was designed to test the hypothesis that hypocaloric nutrition induces anabolism in patients who receive effective segmental pain relief using perioperative epidural analgesia.

METHODS

Sixteen patients who underwent colorectal surgery and received epidural analgesia were randomly assigned to receive intravenous glucose either without (glucose only) or with amino acids (nutrition). Feeding was administered over 48 h from surgical skin incision until the second day after operation. Glucose provided 50 per cent of the patient's resting energy expenditure (REE). Amino acids were infused at rates that provided 20 per cent of REE. Leucine rate of appearance (Ra), leucine oxidation and non-oxidative leucine disposal (NOLD) were assessed by measuring L-[1-13C]leucine kinetics. A positive leucine balance, that is the difference between NOLD and leucine Ra, indicated anabolism.

RESULTS

After surgery, leucine Ra in the nutrition group was lower than that in the glucose only group (mean(s.d.) 88(25) versus 131(22) micromol per kg per h). The leucine balance remained negative in the glucose only group, whereas it became positive in the nutrition group (mean(s.d.) -24(3) versus 38(12) micromol per kg per h; P < 0.001).

CONCLUSION

Patients who receive hypocaloric parenteral nutrition can be rendered anabolic after colorectal surgery in the presence of epidural analgesia.

Effect of desflurane/remifentanil anaesthesia on glucose metabolism during surgery: a comparison with desflurane/epidural anaesthesia

BACKGROUND

The aim of this study was to investigate the effect of general anaesthesia combined with remifentanil or epidural blockade on glucose metabolism during surgery.

METHODS

We randomly assigned patients undergoing elective colorectal surgery to receive either desflurane anaesthesia supplemented with intravenous remifentanil (n = 7) or desflurane anaesthesia supplemented with epidural bupivacaine (n = 7). Plasma concentrations of glucose, lactate, free fatty acids (FFA), insulin, glucagon and cortisol were measured before and after 2 h of surgery. Pre- and intraoperative whole body glucose production and glucose clearance, an indicator of glucose uptake, were determined by an isotope dilution technique using [6,6-2H2]glucose.

RESULTS

In both groups intraoperative glucose production ( P< 0.05) and uptake ( P< 0.05) decreased. Plasma glucose concentrations ( P< 0.05) increased during surgery but did not exceed the normal range (remifentanil group: 5.7 +/- 0.7 mmol l-1, epidural group: 5.8 +/- 0.4 mmol l-1). The plasma concentrations of lactate, FFA, insulin and glucagon remained unchanged during the operation. The plasma cortisol concentration in both groups increased intraoperatively (P< 0.05).

CONCLUSION

Both desflurane/remifentanil and desflurane/epidural anaesthesia decrease the intraoperative rate of whole body glucose production, thereby attenuating the hyperglycaemic response to colorectal surgery.

Effect of epidural blockade on protein, glucose, and lipid metabolism in the fasted state and during dextrose infusion in volunteers

BACKGROUND

To interpret correctly the results from studies performed during surgery and anesthesia it is necessary to dissect the separate effect of the anesthetic technique itself. The purpose of this study was to investigate the metabolic effects of epidural blockade (T7-S1) with bupivacaine 0.25% after 12 h fasting and during administration of 4 mg x kg(-1) x min(-1) dextrose in six healthy volunteers.

METHODS

Each volunteer was assigned to randomly undergo a 6-h multiple stable isotope infusion study (3 h fasted, 3 h dextrose infusion) with or without epidural blockade. L-[1-13C]leucine, [6,6-2H2]glucose, and [1,1,2,3,3-2H5]glycerol were infused to measure protein synthesis, breakdown, and amino acid oxidation; glucose production and clearance; and lipolysis. Plasma concentrations of glucose, lactate, glycerol, free fatty acids, insulin, and glucagon were determined.

RESULTS

Epidural blockade with bupivacaine had no influence on protein oxidation, breakdown and synthesis, glucose production, glucose clearance and lipolysis in the fasted state. Plasma concentrations of metabolic substrates and hormones also were not affected. Dextrose infusion significantly increased glucose clearance and plasma concentrations of glucose and insulin, while endogenous glucose production and lipolysis decreased to a similar degree in both groups. Protein synthesis, breakdown, and oxidation did not change during dextrose infusion.

CONCLUSIONS

Epidural blockade with bupivacaine in the absence of surgery has no effect on fasting protein, glucose, and lipid metabolism. Epidural blockade does not modify the inhibitory influence of dextrose administration on endogenous glucose production and lipolysis.

Atomised lidocaine for airway topical anaesthesia in the morbidly obese: 1% compared with 2%

Airway anaesthesia using atomised lidocaine for awake oral fibreoptic intubation in morbidly obese patients was evaluated using two doses of local anaesthetic. In this randomised, blinded prospective study, 40 ml of atomised 1% (n = 11) or 2% (n = 10) lidocaine was administered with high oxygen flow as carrier. Outcomes included time for intubation, patient tolerance to airway manipulation, haemodynamic parameters, the bronchoscopist's overall satisfaction, and serial serum lidocaine concentrations. Patients receiving lidocaine 1% had a longer mean (SD) time from the start of topicalisation to tracheal tube cuff inflation than those receiving lidocaine 2% (8.6 (0.9) min vs 6.9 (0.5) min, respectively; p < 0.05). Patients in the 1% cohort demonstrated increased responses to airway manipulation (p < 0.0001), reflecting lower bronchoscopist's satisfaction scores (p < 0.03). Haemodynamic responses to topicalisation and airway manipulation were similar in both groups. Peak plasma concentration was lower in the 1% group (mean (SD) 1.4 (0.3) and 3.8 (0.5) microg.ml(-1), respectively; p < 0.001). Airway anaesthesia using atomised lidocaine for awake oral fibreoptic intubation in the morbidly obese is efficacious, rapid and safe. Compared with lidocaine 1%, the 2% dose provides superior intubating conditions.

Reliability of pressure waveform analysis to determine correct epidural needle placement in labouring women

Pressure waveform analysis provides a reliable confirmatory adjunct to the loss-of-resistance technique to identify the epidural space during thoracic epidural anaesthesia, but its role remains controversial in lumbar epidural analgesia during labour. We performed an observational study in 100 labouring women of the sensitivity and specificity of waveform analysis to determine the correct location of the epidural needle. After obtaining loss-of-resistance, the anaesthetist injected 5 ml saline through the epidural needle (accounting for the volume already used in the loss-of-resistance). Sterile extension tubing, connected to a pressure transducer, was attached to the needle. An investigator determined the presence or absence of a pulsatile waveform, synchronised with the heart rate, on a monitor screen that was not in the view of the anaesthetist or the parturient. A bolus of 4 ml lidocaine 2% with adrenaline 5 μg.ml^-1 was administered, and the epidural block was assessed after 15 min. Three women displayed no sensory block at 15 min. The results showed: epidural block present, epidural waveform present 93; epidural block absent, epidural waveform absent 2; epidural block present, epidural waveform absent 4; epidural block absent, epidural waveform present 1. Compared with the use of a local anaesthetic bolus to ascertain the epidural space, the sensitivity, specificity, positive and negative predictive values of waveform analysis were 95.9%, 66.7%, 98.9% and 33.3%, respectively. Epidural waveform analysis provides a simple adjunct to loss-of-resistance for confirming needle placement during performance of obstetric epidurals, however, further studies are required before its routine implementation in clinical practice.

Intraoperative epidural blockade prevents the increase in protein breakdown after abdominal surgery

BACKGROUND

The aim of this study was to investigate the effect of epidural blockade with bupivacaine, restricted to the intraoperative period, on protein catabolism after major abdominal surgery.

METHODS

Fourteen patients undergoing cystoprostatectomy were randomly assigned to receive either general anaesthesia with isoflurane (control group, n=7) or a combination of general anaesthesia and epidural blockade with bupivacaine from segment T4 to S5 (epidural group, n=7). Rates of urea (Ra urea) and glucose production (Ra glucose) were measured three days before and three days after the operation using stable isotope tracers ([15N2]urea, [6,6-2H2]glucose). Protein breakdown was calculated from the urea production rate. Plasma concentrations of metabolic substrates (urea, glucose, lactate, glycerol, amino acids) and hormones (insulin, glucagon, cortisol, adrenaline, noradrenaline) were also determined.

RESULTS

Protein breakdown significantly increased after surgery in the control group (P<0.05), while it remained unaltered in the epidural group (control; 66 (54-76), epidural; 43 (29-58) mg x kg(-1) x h(-1), P<0.05, median (range)). Glucose plasma concentration and Ra glucose increased in both groups to a similar extent (P<0.05). Plasma concentration of branched chain amino acids decreased after epidural analgesia to a value significantly lower than in the control group (P<0.05). Glutamine plasma concentration decreased in the control group (P<0.05), but did not change in the epidural group. There were no differences in plasma concentrations of insulin, cortisol and catecholamines between the two groups. Glucagon plasma concentration in the epidural group was significantly lower than in the control group (P<0.05).

CONCLUSION

Intraoperative epidural blockade inhibits the increase in protein breakdown after abdominal surgery.

Time of peritoneal cavity exposure influences postoperative glucose production

PURPOSE

To examine the effect of the duration of peritoneal cavity exposure on glucose metabolism after abdominal surgery.

METHODS

In eight otherwise healthy patients (ASA 1) with uterine myoma, endogenous glucose production (Ra glucose) was measured immediately before and two hours after abdominal hysterectomy by a stable isotope dilution technique using primed continuous infusions of [6,6-2H2]-glucose. Plasma concentrations of glucose, lactate, insulin, glucagon, cortisol, epinephrine and norepinephrine were determined before, during (5 and 60 min after peritoneal incision, skin closure) and two hours after surgery. Pre- and postoperative glucose clearance was calculated as Ra glucose divided by plasma glucose concentration.

RESULTS

Ra glucose increased from 11.8 +/- 1.2 to 16.8 +/- 3.2 micromol x kg(-1) x min(-1) two hours after hysterectomy (P < 0.05) with a correlation between the degree of increase and the time of peritoneal cavity exposure (r = 0.859, P = 0.006). Plasma glucose concentration increased after surgery from 4.7 +/- 0.8 to 8.3 +/- 1.9 mmol x l(-1) (P < 0.05), while glucose clearance decreased from 2.6 +/- 0.4 to 2.1 +/- 0.4 ml x kg(-1) x min(-1) (P < 0.05). Plasma concentrations of cortisol and catecholamines increased after hysterectomy (cortisol from 6 +/- 2 to 31 +/- 7 microg x dl(-1), epinephrine from 25 +/- 14 to 205 +/- 132 pg x ml(-1), norepinephrine from 182 +/- 82 to 377 +/- 132 pg x ml(-1), P < 0.05), whereas plasma lactate, insulin and glucagon concentrations remained unchanged.

CONCLUSION

The magnitude of increase of glucose production after abdominal hysterectomy is associated with the duration of peritoneal cavity exposure.

[Clonidine compared to midazolam for intravenous premedication for ambulatory procedures. A controlled double blind study in ASA 1 patients]

OBJECTIVE

Midazolam is frequently used for premedication in day-case surgical patients whereas clonidine is rarely administered for this indication. However, clonidine has several useful effects that make the drug an interesting alternative to conventional premedicants. Thus, in this randomised, double-blind, and controlled study the anxiolytic effect of midazolam was compared to that of clonidine. Furthermore, effects on postoperative complaints and minor complications, and readiness for discharge were investigated.

METHODS

100 ASA-1 patients undergoing wisdom teeth extraction on a day-case basis were included into the analysis. A further 50 patients who received no premedication served as a control group. General anaesthesia was standardised (propofol-fentanyl-isoflurane in N2O/O2). The anxiolytic effect of the premedication was assessed using the Erlanger anxiety- and tension scale (EAS). The test was applied before and after intravenous premedication with 1.5 micrograms/kg clonidine or 50 micrograms/kg midazolam and repeated once postoperatively. During recovery the incidence and severity of pain, nausea and vomiting, and shivering were recorded. The readiness for discharge was assessed using standardised discharge criteria. The recording of data was completed by a telephone interview on the day after surgery.

RESULTS

The demographic data of the groups did not differ. In the two treatment groups there was a time-dependent decrease of anxiety and tension. However, postoperatively there was no difference between the levels of anxiety and inner tension between the premedicated patients and the untreated control group. Furthermore there was no difference in the incidence and severity of any postoperative complications. Time until the patients were ready for discharge did not differ between the three groups.

CONCLUSION

The effects of an intravenous premedication with 1.5 micrograms/kg clonidine or 50 micrograms/kg midazolam, respectively in young ASA-1 patients undergoing minor surgical procedures on a day-case basis are restricted to decrease of anxiety and inner tension before surgery. No beneficial effects were found during the postoperative period compared with untreated control patients.

Propofol/sufentanil anesthesia suppresses the metabolic and endocrine response during, not after, lower abdominal surgery

We investigated the influence of propofol/sufentanil anesthesia on metabolic and endocrine responses during, and immediately after, lower abdominal surgery. Twenty otherwise healthy patients undergoing abdominal hysterectomy for benign myoma received either continuous infusions of propofol supplemented with sufentanil (0.01 microg. kg(-1). min(-1), n = 10) or enflurane anesthesia (enflurane, n = 10). Plasma concentrations of glucose, lactate, free fatty acids, triglycerides, insulin, glucagon, cortisol, epinephrine, and norepinephrine were measured before, during, and 2 h after surgery. Pre- and postoperative endogenous glucose production (R(a) glucose) was analyzed by an isotope dilution technique by using [6,6-(2)H(2)] glucose. Propofol/sufentanil anesthesia prevented the increase in plasma cortisol and catecholamine concentrations and attenuated the hyperglycemic response during surgery without showing any difference after the operation. Mediated through a higher glucagon/insulin quotient (propofol/sufentanil 15 +/- 7 versus enflurane 8 +/- 4 pg/microU, P < 0.05), the R(a) glucose postoperatively increased more in the propofol/sufentanil than in the enflurane group (propofol/sufentanil 15.6 +/- 2.0 versus enflurane 13.4 +/- 2.2 micromol. kg(-1). min(-1), P < 0.05).

IMPLICATIONS

The concept of stress-free anesthesia using propofol combined with sufentanil is valid only during surgery. The metabolic endocrine stress response 2 h after the operation is more pronounced than after inhaled anesthesia.

Assessment of perioperative glycerol metabolism by stable isotope tracer technique

The aim of this study was to investigate metabolic changes during and after abdominal hysterectomy with specific regard to glycerol metabolism. Seven otherwise healthy patients with benign uterine myoma were enrolled in this study. Glycerol turnover and hepatic glucose production were measured before and after the operation by using stable-isotope technique ([1,1,2,3,3-2H5]-glycerol, [6,6-2H2]-glucose). Metabolic substrates (glycerol, nonesterified fatty acids, beta-hydroxybutyrate, glucose, lactate) and hormones (insulin, glucagon, cortisol, catecholamines) were determined pre-, intra- and postoperatively. Hysterectomy was associated with an increase of postoperative glycerol turnover from 3.56 +/- 1.28 to 6.46 +/- 2.44 mumol.kg-1.min-1 (P < 0.05). This increment was inversely related to the age of the patients (r = 0.872, P < 0.05). Glycerol concentration tended to increase perioperatively. These changes, however, were not of statistical significance. Hepatic glucose production and glucose plasma levels increased postoperatively from 9.75 +/- 1.61 to 12.79 +/- 1.45 mumol.kg-1.min-1 (P < 0.05) and 4.6 +/- 0.9 to 6.2 +/- 0.9 mmol/L (P < 0.05), respectively. Cortisol and catecholamine levels rose during and after surgery, while insulin and glucagon remained unchanged. The enhanced rate of lipolysis after hysterectomy was not detectable from plasma glycerol levels alone. The results of this study showed that using stable isotope technique allowed a more differentiated look at metabolic pathways than static plasma substrate concentrations, especially under perioperative conditions.

Glucose infusion does not suppress increased lipolysis after abdominal surgery

The purpose of this study was to investigate the effect of glucose infusion on lipid metabolism after abdominal surgery. Patients (n = 6) with non-metastasized colorectal carcinoma were investigated on the second day after surgery and healthy volunteers were studied after an overnight fast. The rates of glycerol appearance (R(a) glycerol), i.e., lipolysis rates, were assessed by primed continuous infusion of [1,1,2,3,3,-5H2]glycerol before and after 3 h of glucose infusion (4 mg x kg(-1) x min(-1)). Plasma concentrations of glycerol, free fatty acids, glucose, lactate, insulin, and glucagon were determined. Fasting R(a) glycerol was higher in patients than in volunteers (7.7 +/- 1.8 versus 1.9 +/- 0.3 micromol x kg(-1) x min(-1), P < 0.05). Glucose infusion suppressed the R(a) glycerol in volunteers to 1.0 +/- 0.2 micromol x kg(-1) x min(-1) (P < 0.05), whereas lipolysis was not affected in patients. Plasma concentrations of glycerol and free fatty acids similarly decreased during glucose administration by 50% in both groups (P < 0.05). In contrast to the patients, a significant correlation (r = 0.78, P < 0.05) between the R(a) glycerol and plasma glycerol concentration was observed in normal subjects. The hyperglycemic response to glucose infusion was significantly more pronounced (P < 0.05) in patients (10.7 +/- 0.7 mmol/L) than in volunteers (7.1 +/- 0.4 mmol/L), whereas the plasma insulin increased to the same extent in the two groups (P < 0.001). In conclusion, lipolysis rates are increased after abdominal surgery and glucose administration, most likely due to insulin resistance, and fail to inhibit stimulated whole-body lipolysis.