Influence of extradural morphine on the adrenocortical and hyperglycaemic response to surgery

[The "Big Five" of Invasiveness - the Usefulness of Drains, Probes and Catheters in Colorectal Surgery]

The perioperative management of colorectal resections is often dominated by traditional procedures and a strong focus on safety. Evidence-based measures such as those established in Fast Track or ERAS programs, are rarely applied in a standardised manner. As part of elective colorectal surgery, many patients therefore continue to routinely receive central venous access, peridural catheters, urinary catheters, drains and/or gastric tubes ("Big Five" of invasiveness). This article presents the currently available evidence on these measures in colorectal surgery. In addition, results relating to the "Big Five" from the author's own centre are presented. This review shows that the "Big Five" of invasiveness are clinically unnecessary or supported by evidence. In addition, they often impair the patient's function.

Chronic Opioid Use Is Associated With Surgical Site Infection After Lumbar Fusion

STUDY DESIGN

Retrospective, database review.

OBJECTIVE

The purpose of this study was to explore the association between preoperative opioid use and postoperative infection requiring operative wound washout in elective lumbar fusion patients.

SUMMARY OF BACKGROUND DATA

Numerous peer-reviewed publications have conducted multivariate analyses of risk factors for surgical site infection. However, few have explored preoperative opioid use. Opioids have been widely prescribed preoperatively for pain management, but their effect on postsurgical infection is currently inconclusive.

METHODS

We retrospectively queried the PearlDiver national insurance claims database and included patients from 2007 to 2017 with a history of lumbar fusion. Any interbody fusion history designated exclusion. We stratified patients by single or multilevel procedures and conducted univariate analyses of previously documented infection risk factors, as well as our variable of interest, chronic preoperative opioid use. Variables associated (P < 0.100) with the outcome measure of 90-day postoperative infection treated with operative irrigation and wound debridement were included in a multivariate analysis.

RESULTS

A total of 12,519 patients matched our inclusion criteria. Among the single-level cohort, only diabetes was observed to be associated with infection requiring operative wound washout and thus no subsequent regression was performed. For the cohort of patients who underwent multilevel fusion, chronic opioid use, diabetes, congestive heart failure, chronic obstructive pulmonary disease, and hypertension trended toward significance in the univariate analysis and were included in a logistic regression model. In the multivariate analysis, chronic opioid use (odds ratio [OR] = 1.435, P = 0.025), diabetes (OR = 1.591 P = 0.003), and congestive heart failure (OR = 1.929, P = 0.003) were identified as independent risk factors for infection requiring operative wound washout.

CONCLUSION

In this analysis, preoperative opioid use was significantly associated with infection requiring operative wound washout in multilevel lumbar fusion patients. Limiting opioid consumption may have the benefit of reducing the risk of infection following spine surgery.

LEVEL OF EVIDENCE

3.

Cortisol and Insulin Levels during Major Gynaecological Operations: The influence of Two Anaesthetic Techniques

BACKGROUND: Metabolic and hormonal changes are noticed within the first few hours after surgical injury. These changes are influenced by the intensity, duration, type of injury, and the anaesthetic techniques.AIM: To investigate the effects of anaesthesia on cortisol, insulin and glucose concentrations during major gynaecological surgeries.METHODS: Forty patients were randomly allotted to receive either balanced general anaesthesia (n=20) or combined spinal epidural anaesthesia extending from T5 to S5 (n=20). Blood samples were collected for cortisol and glucose at preinduction, 1, 3 and 4 hours, and for insulin at preinduction and 24 hours after incision.RESULTS: The mean cortisol concentration was significantly lower 4 hours after incision with combined spinal epidural anaesthesia (19.96 ± 11.32) μg/dl than with balanced general anaesthesia (38.94 ± 10.6) μg/dl, p = 0.018. The mean insulin concentration, 24 hours after incision decreased with combined spinal epidural anaesthesia, but increased with balanced general anaesthesia p = 0.403. The mean glucose concentrations were significantly lower with combined spinal epidural anaesthesia than with balanced general anaesthesia during the 4 hour study period p ≤ 0.05.CONCLUSION: combined spinal epidural anaesthesia extending from T5 to S5 resulted in lower cortisol, insulin and glucose concentrations during major gynaecological surgeries. This may be of benefit in patients scheduled for surgical operations below the umbilicus.

Comparison of Stress Hormone Response, Interleukin-6 and Anaesthetic Characteristics of Two Anaesthetic Techniques: Volatile Induction and Maintenance of Anaesthesia using Sevoflurane versus Total Intravenous Anaesthesia using Propofol and Remifentanil

This prospective randomized study compared the effects of two types of anaesthesia on peri-operative anaesthetic profiles from induction to recovery and on immunological and neurohormonal responses to anaesthesia and surgical stress. Forty patients were assigned to undergo either volatile induction and maintenance of anaesthesia (VIMA) with sevoflurane or total intravenous anaesthesia (TIVA) with propofol and remifentanil. Plasma adrenaline, noradrenaline, cortisol, glucose and interleukin-6 (IL-6) levels were measured at baseline, induction, incision and extubation. TIVA produced a significantly lower intubation score, shorter time to intubation and faster waking time than VIMA, but recovery profiles did not differ. Adrenaline, noradrenaline, cortisol and glucose levels were significantly lower with TIVA than VIMA, but there was no difference in IL-6 levels between the two groups. TIVA with propofol and remifentanil may be preferable to VIMA with sevoflurane alone because it leads to smoother, more rapid induction, more rapid awakening and lower stress responses to surgical stimuli.

The effect of combined spinal-epidural anesthesia on stress responses during total knee replacement

BACKGROUND

Intraoperative stress may evoke various changes in hormonal secretion and autonomic nervous system activity. We designed this study to investigate the effect of combined spinal-epidural anesthesia on stress hormone responses.

METHODS

Thirty women more than 60 years of age, undergoing bilateral total knee replacement surgery were studied. Patients were randomized to receive either general anesthesia (group I), or combined spinal-epidural anesthesia (group II). Blood samples were obtained immediately before anesthesia induction, immediately after skin incision, after first knee prosthesis insertion, and end of operation, immediately for measurement of cortisol, epinephrine, and norepinephrine.

RESULTS

The plasma concentration of cortisol, epinephrine and norepinephrine were significantly lower in group II after the prosthesis insertion and at the end of operation, immediately. The plasma concentration of cortisol was significantly higher than basal values in both of two groups through the surgery.

CONCLUSIONS

Combined spinal-epidural anesthesia has the blocking effect of releasing catecholamine during total knee replacement surgery and immediately after the surgery. The effect of combined spinal-epidural anesthesia on stress responses during total knee replacement is better than that of general anesthesia.

Electroacupuncture analgesia in dogs: is there a difference between uni- and bi-lateral stimulation?

OBJECTIVE

To compare the analgesic effect of uni- and bi-lateral electroacupuncture (EA) in response to thermal and mechanical nociceptive stimuli and to investigate the cardiorespiratory, endocrine, and behavioral changes in dogs submitted to EA.

STUDY DESIGN

Prospective, randomized cross-over experimental study.

ANIMALS

Eight adult, clinically healthy, cross-breed dogs, weighing 13 +/- 4 kg.

METHODS

Dogs underwent electrostimulation at false acupoints (T-false); bilateral EA at acupoints, stomach 36, gall bladder 34 and spleen 6 (T-EA/bil); unilateral EA at the same points (T-EA/uni) or were untreated (T-control). All animals received acepromazine (0.05 mg kg(-1)) IV; and heart rate, pulse oximetry, indirect arterial blood pressure, respiratory rate, Pe'CO(2), rectal temperature, and plasma cortisol concentration were measured before, during, and after EA. Analgesia was tested using thoracic and abdominal cutaneous thermal and mechanical stimuli, and an interdigital thermal stimulus. Behavior was classified as calm or restless. Analysis of variance for repeated measures followed by Tukey's test was used for analysis of the data.

RESULTS

There were no cardiorespiratory differences among the treatments. The cutaneous pain threshold was higher after EA, compared with false points. The latency period was shorter and analgesia was more intense in T-EA/bil than T-EA/uni, when both were compared with T-false and T-control. Six out of eight animals treated with EA were calm during treatment, and 5/8 and 4/8 of the T-false and T-control animals, respectively, were restless. Latency to interdigital thermal stimulation increased in T-EA/bil compared with the others. There was no difference in plasma cortisol concentrations among the treatments.

CONCLUSIONS

Bilateral EA produced a shorter latency period, a greater intensity, and longer duration of analgesia than unilateral stimulation, without stimulating a stress response.

CLINICAL RELEVANCE

Bilateral EA produces a better analgesic effect than unilateral EA.

Comparison of postoperative pain management techniques on endocrine response to surgery: a randomised controlled trial

The present study compared three postoperative pain management techniques in patients undergoing lower abdominal surgery: intermittent opiate regimen (IOR), patient-controlled analgesia (PCA), and patient-controlled epidural analgesia (PCEA), on cortisol and prolactin levels during the first 48 h postoperatively. Ninety-two patients scheduled for a lower abdominal surgery, were randomly assigned to one of three study groups: IOR (N=31), PCA (N=31), and PCEA (N=30). Patients of the IOR group received postoperatively 50-75 mg of pethidine IM on demand. Patients of the PCA group received a loading dose of morphine (3-4 mg), followed by 1mg bolus of morphine IV per demand. Patients of the PCEA group received 3 ml of 0.1% bupivacaine plus 2 microg/ml of fentanyl per demand, with continuous background infusion of 6ml/h. Venous blood samples were collected preoperatively, and 24 and 48 h after surgery, and were later assayed for serum cortisol and prolactin levels. Patients of the PCEA group exhibited diminished postoperative elevation of serum cortisol levels at 24 and 48 h (24.4, 18.6 microg/dl, respectively) compared with both IOR (31.9, 21.9) and PCA (28.5, 22.3) groups. Similarly, patients of the PCEA group exhibited diminished postoperative elevation of serum prolactin level (20.7, 15.7 ng/mL) compared with PCA (24.9, 17.1) group. The present results indicate that the PCEA technique offers an advantageous treatment associated with reduced postoperative pain, and attenuated neuroendocrine response.

Effects of surgical stress on brain prostaglandin E2 production and on the pituitary–adrenal axis: Attenuation by preemptive analgesia and by central amygdala lesion

Surgical stress is the combined result of tissue injury, anesthesia, and postoperative pain. It is characterized by elevated levels of adrenocorticotropin (ACTH), corticosterone (CS), and elevated levels of prostaglandin E2 (PGE2) in the periphery and in the spinal cord. The present study examined the effects of perioperative pain management in rats undergoing laparotomy on serum levels of ACTH, CS, and on the production of PGE2 in several brain regions, including the amygdala. The amygdala is known to modulate the pituitary-adrenal axis response to stress. We, therefore, also examined the effects of bilateral lesions in the central amygdala (CeA) on laparotomy-induced activation of the pituitary-adrenal axis in rats. In the first experiment, rats either underwent laparotomy or were not operated upon. Half the rats received preemptive analgesia extended postoperatively, the other received saline. ACTH, CS serum levels, and ex vivo brain production of PGE2 were determined. In the second experiment, rats underwent bilateral lesions of the CeA. Ten days later, rats underwent laparotomy, and ACTH and CS serum levels were determined. Laparotomy significantly increased amygdala PGE2 production, and CS and ACTH serum levels. This elevation was markedly attenuated by perioperative analgesia. Bilateral CeA lesions also attenuated the pituitary-adrenal response to surgical stress. The present findings suggest that the amygdala plays a regulatory role in mediating the neuroendocrine response to surgical stress. Effective perioperative analgesia attenuated the surgery-induced activation of pituitary-adrenal axis and PGE2 elevation. The diminished elevation of PGE2 may suggest a mechanism by which pain relief mitigates pituitary-adrenal axis activation.

Epidural analgesia in gastrointestinal surgery

BACKGROUND

The ideal perioperative analgesia should provide effective pain relief, avoid the detrimental effects of the stress response, be simple to administer without the need for intensive monitoring, and have a low risk of complications.

METHODS

This review defines the physiological effects of epidural analgesia and assesses whether the available evidence supports its preferential use in gastrointestinal surgery. All papers studied were identified from a Medline search or selected by cross-referencing.

RESULTS

Epidural analgesia is associated with a shorter duration of postoperative ileus, attenuation of the stress response, fewer pulmonary complications, and improved postoperative pain control and recovery. It does not reduce anastomotic leakage, intraoperative blood loss, transfusion requirement, risk of thromboembolism or cardiac morbidity, or hospital stay compared with that after conventional analgesia in unselected patients undergoing gastrointestinal surgery. Thoracic epidural analgesia reduces hospital costs and stay in patients at high risk of cardiac or pulmonary complications.

CONCLUSIONS

Epidural analgesia enhances recovery after gastrointestinal surgery. The results support the development of structured regimens of early postoperative feeding and mobilization to exploit the potential for thoracic epidural analgesia to reduce hospital stay after gastrointestinal surgery.

Effects of systemic and epidural morphine on antidiuretic hormone levels in children

BACKGROUND

Although the use of opioids during general anaesthesia suppresses stress response to surgery and pain, the effects on antidiuretic hormone (ADH) are controversial. The aim of this study was to find the effects of morphine with either intravenous infusion or epidural route on ADH and other stress hormones.

METHODS

Fifty children aging (1-15 years) undergoing major genito-urinary or abdominal operations were included in this study. The patients were allocated randomly to two groups receiving either a single dose of epidural morphine 0.1 mg.kg-1 (EP group, n = 25) postinduction or morphine infusion (INF group; n = 25) at 0.02 mg.kg-1.h-1 following 0.05 mg.kg-1 bolus. Blood samples were withdrawn for plasma ADH, osmolality, glucose, cortisol, insulin and morphine level analysis following induction and 1, 5, 12 and 24 h after initial morphine administration.

RESULTS

The two groups were similar in demographic factors, pain scores, sedation scores, and incidence of nausea and vomiting. The amount of morphine received was different between groups and the changes in serum levels of morphine were statistically significant in EP group ( P < 0.05). The changes in cortisol, blood glucose and insulin levels were insignificant in both groups (P > 0.05). The changes of ADH levels were significant at time-points in both groups, reaching control levels at the 24th hour (P < 0.05).

CONCLUSION

Despite the effective pain therapy and suppression of cortisol and insulin response to surgical stimulus, the increase in ADH secretion is not effected by systemic or epidural morphine administration.

The analgesic efficacy and neuroendocrine response in paediatric patients treated with two analgesic techniques: using morphine-epidural and patient-controlled analgesia

BACKGROUND

Pain treatment is one of the main concerns of paediatric anaesthesiologists. The purpose of this study was to assess and compare the quality of analgesia and stress suppression by morphine when used [epidural (single shot) (EP) or with intravenous (i.v.) for patient-controlled analgesia (PCA) in children].

METHODS

Forty-four children, aged 5-15 years, and who were undergoing major genitourinary or lower abdominal surgery with a standardized general anaesthesia technique, were included in this study. In the EP group (n=24) 0.1 mg x kg(-1) morphine in 0.2 ml x kg(-1) saline were given epidurally at the L3-4 level and in the PCA group (n=20) 0.1 mg x kg-1 morphine was given i.v. immediately after intubation. Postoperative PCA bolus doses were 0.5 mg for patients weighing less than 20 kg, 1 mg for children weighing 20-30 kg and 1.5 mg for children weighing 30-40 kg. Blood samples were withdrawn following induction and at 1, 8, 12 and 24 h after morphine administration for measurement of blood glucose, insulin, cortisol and morphine levels. Patients were observed for 24 h postoperatively; heart rate, systolic blood pressure, respiratory rate, FACES pain scores, sedation scores and complications were recorded.

RESULTS

The PCA group received 0.56 +/- 0.33 mg x kg(-1) x day(-1) morphine. The FACES pain scores, sedation scores, cortisol, blood glucose and insulin levels were similar in both groups. Haemodynamic and respiratory evaluations and cortisol levels were stable but blood glucose and insulin changes at certain time periods were significant (P < 0.05). Serum morphine levels and incidence of vomiting were different between groups (P < 0.05). Serum morphine levels were similar at the first hour.

CONCLUSIONS

Both techniques provided sufficient pain relief and attenuated the hormonal response without life-threatening complications.

Reduction of postoperative mortality and morbidity with epidural or spinal anaesthesia: results from overview of randomised trials

OBJECTIVES

To obtain reliable estimates of the effects of neuraxial blockade with epidural or spinal anaesthesia on postoperative morbidity and mortality.

DESIGN

Systematic review of all trials with randomisation to intraoperative neuraxial blockade or not.

STUDIES

141 trials including 9559 patients for which data were available before 1 January 1997. Trials were eligible irrespective of their primary aims, concomitant use of general anaesthesia, publication status, or language. Trials were identified by extensive search methods, and substantial amounts of data were obtained or confirmed by correspondence with trialists.

MAIN OUTCOME MEASURES

All cause mortality, deep vein thrombosis, pulmonary embolism, myocardial infarction, transfusion requirements, pneumonia, other infections, respiratory depression, and renal failure.

RESULTS

Overall mortality was reduced by about a third in patients allocated to neuraxial blockade (103 deaths/4871 patients versus 144/4688 patients, odds ratio=0.70, 95% confidence interval 0.54 to 0.90, P=0. 006). Neuraxial blockade reduced the odds of deep vein thrombosis by 44%, pulmonary embolism by 55%, transfusion requirements by 50%, pneumonia by 39%, and respiratory depression by 59% (all P<0.001). There were also reductions in myocardial infarction and renal failure. Although there was limited power to assess subgroup effects, the proportional reductions in mortality did not clearly differ by surgical group, type of blockade (epidural or spinal), or in those trials in which neuraxial blockade was combined with general anaesthesia compared with trials in which neuraxial blockade was used alone.

CONCLUSIONS

Neuraxial blockade reduces postoperative mortality and other serious complications. The size of some of these benefits remains uncertain, and further research is required to determine whether these effects are due solely to benefits of neuraxial blockade or partly to avoidance of general anaesthesia. Nevertheless, these findings support more widespread use of neuraxial blockade.

Acupuncture for management of pain

Acupuncture is the technique of inserting needles into specific areas of the body to elicit a physiologic response. Although acupuncture is based on the paradigms of traditional Chinese medicine, there are numerous physiologic and clinical studies that document and validate its use. Control of pain is a major indication for the use of acupuncture. It can be used in conjunction with analgesic drugs or alone to make patients more comfortable.

Perioperative myocardial cell injury: the relationship between troponin T and cortisol

STUDY OBJECTIVE

To investigate whether there is an association between Troponin T (TnT), reflecting myocardial cell injury, and cortisol, reflecting the degree of surgical trauma and associated stress, in light of our recent evaluation of TnT as a marker of perioperative myocardial cell injury.

DESIGN

Prospective, cohort study.

PATIENTS

70 patients (67.4 +/- 8.7 yrs) with definite or at-risk coronary artery disease (CAD) undergoing elective noncardiac surgery (vascular n = 38, abdominal n = 21, orthopedic n = 8) with general (n = 63) or regional (n = 4) anesthesia with postoperative on-demand analgesia.

MEASUREMENTS AND MAIN RESULTS

Morning blood samples for TnT (upper limit of normal: <0.2 ng/mL), CK-MB (reference range </=12 U/L), and cortisol (normal morning range 7-25 mcg/dL) were taken on the day before surgery, on the morning of surgery before induction of anesthesia, and on the first 5 postoperative days. Data were compared by analysis of variance. Three patients were excluded from the study because of incomplete blood samples of TnT or cortisol. Preoperative mean cortisol levels (mcg/dL +/- SD) were within the normal range and equal in TnT positive (n = 13) and negative (n = 54) patients (16.1 +/- 4.5 vs. 15.6 +/- 5.8). On the 1st postoperative day, there was a substantial increase of cortisol in the TnT positive group (35.7 +/- 26.9). Cortisol remained high until the 5th postoperative day (24.7 +/- 9. 4). There was a significant difference in the cortisol concentration in TnT-positive compared to TnT-negative patients (p < 0.001), a significant difference in the perioperative cortisol concentration over time (p < 0.05), and a significant interaction (p < 0.001). But there was no consistent temporal relationship between the increase of TnT and the increase of cortisol.

CONCLUSIONS

The significant relationship between a highly sensitive and specific marker of myocardial cell injury and a marker of stress suggests that cardiac-risk patients undergoing stressful surgical procedures might benefit from close perioperative TnT monitoring with early recognition of myocardial cell injury.

Analgesic agents for the postoperative period. Opioids

Opioids are the most commonly used medication for patients with acute pain. Morphine is the prototype with which all other opioids are compared. Synthetic and semisynthetic derivatives of morphine have unique properties, allowing for the use of a larger selection of medication. An understanding of the mechanisms of action, adverse effects, and routes of administration of the various potent opioids is important for good postoperative pain management.

Measurement of pain

Pain is a personal, subjective experience influenced by cultural learning, the meaning of the situation, attention, and other psychologic variables. Approaches to the measurement of pain include verbal and numeric self-rating scales, behavioral observation scales, and physiologic responses. The complex nature of the experience of pain suggests that measurements from these domains may not always show high concordance. Because pain is subjective, patients' self-reports provide the most valid measure of the experience. The VAS and the MPQ are probably the most frequently used self-rating instruments for the measurement of pain in clinical and research settings. The MPQ is designed to assess the multidimensional nature of pain experience and has been demonstrated to be a reliable, valid, and consistent measurement tool. A short-form MPQ is available for use in specific research settings when the time to obtain information from patients is limited and when more information than simply the intensity of pain is desired. The DDS was developed using sophisticated psychophysical techniques and was designed to measure separately the sensory and unpleasantness dimensions of pain. It has been shown to be a valid and reliable measurement of pain with ratio-scaling properties and has recently been used in a clinical setting. Behavioral approaches to the measurement of pain also provide valuable data. Further development and refinement of pain measurement techniques will lead to increasingly accurate tools with greater predictive powers.

[Benefit-risk and monitoring modalities of different techniques and methods of postoperative analgesia]

This review aimed to determine the benefits-risks ratio of postoperative analgesia. The various agents usually used for intravenous postoperative analgesia (paracetamol, NSAID's, opioids), and the techniques for postoperative analgesia (PCA, epidural, perinervous block) are analysed. The rules proposed for the monitoring of postoperative analgesia are considered.

[Postoperative locoregional analgesia in the adult: epidural and peripheral techniques. Indications, adverse effects and monitoring]

Regional analgesia is a very effective way to treat postoperative pain. Lumbar and thoracic epidural analgesia are well adapted to major abdominal and thoracic surgery. Nevertheless, respiratory side effects induced by opioids are potentially severe and an adequate monitoring is essential. In orthopaedic surgery, perineural blocks are the best technique to manage postoperative pain and perineural catheters may be used. The importance of intra-articular analgesia, simple and safe, is not fully understood. The association of a local anaesthetic inducing a minor motor block and a strong sensitive block (bupivacaine, ropivacaine), with an opioid seems to be the best pharmacologic choice regarding quality of analgesia and safety. Benefits of postoperative regional analgesia on mortality and morbidity are not demonstrated. Medical and nursing staff and specialized units should improve quality of postoperative regional analgesia as well. General guidelines for the practice of regional anaesthesia must be closely followed.

A surgically placed epidural catheter in a patient with spinal trauma

PURPOSE

To report the successful perioperative anaesthetic and analgesic management of a spinal trauma patient with a surgically placed epidural catheter.

CLINICAL FEATURES

A 15-yr-old adolescent woman sustained an unstable spinal column injury with an incomplete neurological deficit following a high speed motor vehicle accident. She was scheduled for spinal decompression and stabilisation through a left thoracoabdominal approach. Balanced general anaesthesia was undertaken. Prior to closure, a multi-orifice epidural catheter was surgically placed under direct vision 5 cm into the anterior epidural space. The catheter was then tunnelled out through the psoas muscle and secured in place. Combined epidural-general anaesthesia was then initiated for the duration of the case using 5 ml bupivacaine 0.25% after an initial test dose of 3 ml lidocaine 1.5% with epinephrine. An infusion of bupivacaine 0.10% and fentanyl 5 micrograms.ml-1 at 8 ml.hr-1 using patient controlled epidural analgesia (PCEA) provided excellent postoperative pain control for four days. She had an uncomplicated postoperative course.

CONCLUSION

A surgically placed epidural catheter provided excellent, safe, perioperative anaesthesia and analgesia in this patient with unstable spinal trauma.

Total-body oxygen consumption after isoflurane anesthesia: effects of mild hypothermia and combined epidural-general anesthesia

STUDY OBJECTIVES

To determine the effects of epidural anesthesia and avoidance of intraoperative heat loss on the increase in total-body oxygen consumption in the immediate postoperative period after major intraabdominal surgery.

DESIGN

Prospective, randomized (with regard to temperature management) study.

SETTING

University medical center.

PATIENTS

24 ASA physical status I, II, and III adults.

INTERVENTIONS

All patients received either isoflurane-nitrous oxide (N2O)-opioid general anesthesia or combined epidural-general anesthesia; patients were randomly assigned to active intraoperative warming or routine thermal care.

MEASUREMENTS AND MAIN RESULTS

VO2 was measured by indirect calorimetry preoperatively (T0), immediately postoperatively (T1), and 60 to 90 minutes later (T2). For all patients, VO2 was 57 +/- 45% (mean +/- SD) greater at T1 than at T0 (p < 0.05). After isoflurane-N2O-opioid general anesthesia, VO2 increased 15 +/- 20% in normothermic patients (core temperature, 36.4 +/- 0.2 degrees C) compared with 69 +/- 52% in hypothermic patients (35.0 +/- 0.5 degrees C). After combined epidural-general anesthesia, VO2 increased 86 +/- 39% on emergence in normothermic (36.4 +/- 0.2 degrees C) and 58 +/- 11% in hypothermic (35.1 +/- 0.4 degrees C) patients.

CONCLUSIONS

Total-body VO2 was increased in the immediate postoperative period. After general anesthesia, the magnitude of the increase in VO2 was significantly less in normothermic patients than in hypothermic patients. After combined epidural-general anesthesia, VO2 was increased in normothermic and in hypothermic patients.

Autonomic nervous system and neuroendocrine changes in patients with idiopathic trigeminal neuralgia

To investigate sympathetic nervous system and neuroendocrine changes in idiopathic trigeminal neuralgia, we determined the plasma level of the catecholamines norepinephrine and epinephrine, as well as cortisol and ACTH in 16 patients (55.3 +/- 8.3 years) with trigeminal neuralgia at four different times during the day (7.00, 13.00, 17.00 and 23.00). Morning and evening values of plasma norepinephrine as well as the daily mean value (dmv) were significantly higher (p < 0.01) in patients with trigeminal neuralgia than in an age- and gender-matched control group. Moreover, morning, afternoon and dmv epinephrine values were also significantly elevated. The dmv norepinephrine levels correlated with the intensity of the attacks (r = 0.68, p < 0.01), the frequency of the attacks (r = 0.75, p < 0.01) and the duration of the disease (r = 0.78, p < 0.01). In addition to elevated catecholamines, trigeminal neuralgia patients also demonstrated significantly increased morning, evening and daily mean values of plasma cortisol. Thus, patients with trigeminal pain have an increased sympathetic nervous system activity for an extended period of time without a direct link to pain attacks, which suggests that the sympathetic nervous system itself is at least co-activated in trigeminal neuralgia and perhaps plays a role in the induction and maintenance of trigeminal pain. The neuroendocrine changes are similar to cluster headache and point to a central dysregulation of the hypothalamic-pituitary-adrenal axis, possibly due to the cyclic phenomena in idiopathic trigeminal neuralgia.

Lumbar epidural morphine infusions for children undergoing cardiac surgery

OBJECTIVE

To determine whether outcomes and costs in children undergoing cardiac surgery are affected by the method of postoperative pain management.

DESIGN

Retrospective, case control.

SETTING

Tertiary care children's hospital in a university setting.

PARTICIPANTS

Two groups of children undergoing cardiac surgery for palliation or repair of congenital heart disease oer a 21-month period between January 1993 and September 1994.

INTERVENTIONS

Lumbar epidural morphine infusions (LEM) in one group, and IV opioid (IVO) medication in the other for postoperative pain control.

MEASUREMENTS AND MAIN RESULTS

Hospital courses of 27 LEM patients and 27 IVO patients were analyzed. In LEM patients, epidural catheters were placed following anesthetic induction, but before anticoagulation. A bolus of 50 micrograms/kg of preservative-free morphine sulfate was administered through the catheter, followed by a continuous infusion at 3 to 4 micrograms/kg/h for 22 to 102 (median, 46) hours postoperatively. The IVO patients received 50 micrograms/kg, IV, of fentanyl before incision followed by a continuous infusion at 0.3 microgram/kg/min. The fentanyl infusion rate was decreased to 0.1 microgram/kg/min postoperatively and maintained for 24 hours. Although the LEM group was demographically similar to the IVO group, times to tracheal extubation, transfer from the intensive care unit, and resumption of regular diet were significantly shorter in LEM patients. LEM and IVO patients received similar amounts of fentanyl during surgery (10.4 +/- 19.3 micrograms/kg/h v 13.7 +/- 8.1 micrograms/kg/h, p = 0.4). However, during postoperative recovery, LEM patients who were extubated late received significantly less supplemental opioid medication than IVO patients extubated late during the first 5 postoperative days. No complications related to dural puncture, bleeding into the epidural space, or respiratory depression were encountered. Pruritus and nausea/vomiting were the most commonly reported morbidities in both groups. Fifty-six percent (15/27) of LEM patients and 41% of IVO patients reported pruritus (p = 0.4). There was no significant difference in the incidence of nausea and vomiting between the groups (34% v 30%, respectively).

CONCLUSIONS

Given the present methodologic limitations, the authors found improved outcomes only in LEM patients extubated late compared with IVO patients. Randomized, prospective studies to evaluate this conclusion and to determine the comparative efficacy and safety of LEM infusions are in progress.

Epidural anaesthesia and analgesia do not affect energy expenditure after major abdominal surgery

Our objective was to determine the effect of perioperative epidural anaesthesia and analgesia on the increase in energy expenditure which accompanies major elective abdominal surgery in a prospective, randomized study. Eight patients undergoing elective resections of the colon and/or rectum received general anaesthesia alone (nitrous oxide, oxygen, and isoflurane, supplemented with intravenous fentanyl to a maximum of 10 micrograms.kg-1), and 12 patients received perioperative epidural anaesthesia and analgesia using lidocaine (carbonated lidocaine 2% with epinephrine 1:200,000, 20 ml over 30 min) and morphine (preservative-free morphine 0.10 mg.kg-1 after catheter insertion and 0.05 to 0.10 mg.kg-1 every 12 hr as needed until the morning following surgery) via a lower lumbar catheter in addition to general anaesthesia. Respiratory gas exchange was measured using a metabolic cart and canopy system early on the morning of surgery, six hours postoperatively, and on the first and second postoperative mornings. Parenteral analgesic administration (P < 0.001) and visual analogue pain scores (P < 0.05) were lower in the patients receiving epidural anaesthesia and time to first parenteral analgesia was longer (P < 0.005). Oxygen consumption, carbon dioxide production, and energy expenditure increased after surgery (all P < 0.001) but were very similar in the two groups (all P > or = 0.8) before and after surgery. Despite substantial effects on postoperative pain, we conclude that oxygen consumption and energy expenditure following major abdominal surgery are not diminished by perioperative epidural anaesthesia and analgesia.

Perioperative complications of anesthesia

An overview of several perioperative complications and their management strategies is presented. Operative hypothermia, malignant hyperthermia, bronchospasm, and side effects of spinal opioid agents are discussed. Ramifications of these complications may extend well beyond the operative period and influence patient outcome. Therefore, it is necessary that the surgeon have a fundamental understanding of the pathophysiology and modalities of treatment in the context of anesthesia and surgery.

Effects of abdominal surgery on somatosensory evoked potentials during nitrous oxide-enflurane anesthesia

The effect of abdominal surgery on median nerve somatosensory evoked potentials (SEPs) was studied in 8 enflurane and nitrous oxide anesthesia (GOE) patients. We further compared the effect of epidural anesthesia. The first recording was done immediately prior to induction. Anesthesia was then induced with 5 mg.kg(-1) i.v. of thiopental and maintained with 1.0% enflurane, 66% N(2)O and 33% O(2). Before skin incision for abdominal surgery, the second recording was performed under GOE anesthesia and the third recording during surgery. Then 2% lidocaine was injected into the epidural space through a preinserted catheter, and after 15 min the fourth recording was obtained. The latencies of peaks N1, P2 and N2 and the amplitudes of N1-P2 and P2-N2 were measured. The latencies of N1, P2 and N2 increased and the amplitudes of N1-P2 and P2-N2 deceased significantly after the induction of anesthesia compared with the control values. During abdominal surgery the latencies of N1 and P2 decreased and the amplitudes of N1-P2 and P2-N2 increased. After epidural anesthesia, however, the latencies of N1 and P2 increased and the amplitudes of N1-P2 and P2-N2 decreased significantly and returned almost to the values recorded under preoperative GOE anesthesia. These phenomena indicated that the excitations produced by surgical stimulation in nerve ending might have been transmitted to the central nervous system via spinal nerves and blocked by epidural anesthesia.

Reduction of postoperative morbidity following patient-controlled morphine

The present study examined the impact of two methods of pain management on recovery in 38 women undergoing hysterectomy. One group received IV morphine in the recovery room and IM morphine on the ward on a PRN basis (PRN group). In the other group, a loading dose of morphine 8 mg IV was given when the patient first complained of pain and patient-controlled IV morphine (PCA) was initiated and continued for 48 h (PCA group). Both groups received similar amounts of morphine overall, differently distributed over time. The PCA patients received 8 mg.h-1 in the recovery room (approximately 2.5 hrs) and less thereafter. The PRN patients received approximately 2 mg.h-1 for the entire 48-hr period. Pain control was better throughout convalescence and less variable across time with PCA management. Minute ventilation also recovered faster and by day four was 25 per cent above the preoperative baseline in the PCA group. In addition, oral temperature became normal one day earlier, ambulation recovered more rapidly and patients were discharged from hospital earlier. The data suggest that early treatment with relatively high, self-titrated morphine doses may alter the course of the metabolic response to surgery.

[Use of morphinomimetics in regional anesthesia]

Pain relief is one of medicine's most important challenges and the first aim of anaesthesia. The most common technique of postoperative analgesia remains intramuscular or subcutaneous opiates. There has been a better understanding of the mechanisms of action of opiates over the last decade, and new techniques and methods of administration have been developed especially their regional application. In 1979, two reports acted as catalysts to promote further studies. Wang et al. reported on the efficacy of intrathecal morphine to relieve unbearable malignant pain in 8 patients whereas Behar et al reported on the efficacy of morphine by epidural route. More recently, several studies pointed out the usefulness of the peripheral perineural route for opiates. However, this remains controversial, as some discrepancies persist in the results. The classification of opiate receptors and their relationship to opiate analgesia, as well as the mechanisms of action of regionally administered opiates are analyzed. The dual pre- and postsynaptic actions of spinal opiates are then considered. The parts played by the different neurotransmitters and pathways are set out. The evidence for opiate receptors at peripheral nerve sites and the different hypotheses suggested to explain the effect of opiates given by the perineural route are discussed. The pharmacokinetics and pharmacodynamics of opiates given by the subarachnoid and epidural routes are considered, in particular with respect to the comparative pharmacology of the commonly used opiates. The adverse effects of spinal opiates are reviewed, with their potential risks, and their clinical and therapeutic implications. Opiates and local anaesthetics given by the spinal route are compared. The clinical applications of intrathecal and epidural opiates are discussed, especially in the fields of postoperative analgesia, treatment of chest trauma, and cancer pain. Lastly, the few controlled studies concerning the use of opiates in peripheral nerve blocks, especially brachial plexus blocks, and the prospects of this new technique of giving opiates regionally are discussed.

Influence of intraperitoneal anesthesia on pain and the sympathoadrenal response to abdominal surgery

The effects of intraperitoneal administration of bupivacaine on pain and the sympathoadrenal response to surgery were studied in a double-blind randomized trial in 19 patients undergoing cholecystectomy. Bupivacaine (2 mg/kg) was dissolved in 300 ml isotonic saline and administered into the peritoneal cavity 10 min before the operation (n = 9). Saline was administered in a comparable group of patients (n = 10). There were no significant differences in pain scores between the groups during the first day after surgery (P greater than 0.05). Postoperative requirements of pethidine during the first 2 days after surgery did not differ significantly between the groups. Blood glucose levels were significantly lower in the bupivacaine-treated group 1 h (P less than 0.05) and 4 h (P less than 0.05) after skin incision. No significant differences were observed between the groups regarding plasma catecholamine and serum cortisol levels during and after surgery. Differences between the groups regarding urine output of catecholamines during the first and second postoperative days were not significant. Our results suggest that single administration of a local anesthetic intraperitoneally does not reduce pain or the sympathoadrenal response to upper abdominal surgery.

Effect of total intravenous anaesthesia with midazolam/alfentanil on the adrenocortical and hyperglycaemic response to abdominal surgery

The effect of anaesthesia on the hyperglycaemic and adrenocortical response induced by surgery was studied in patients undergoing abdominal hysterectomy. The study group was anaesthetized with midazolam and alfentanil using a totally intravenous anaesthetic technique. A reference group received anaesthesia with thiopentone, alfentanil and nitrous oxide. Midazolam 0.42 mg.kg-1 was given as a loading infusion followed by a maintenance infusion of 0.125 mg.kg-1.h-1. Alfentanil was given as a bolus dose of 0.075 mg.kg-1 in both groups, followed by a loading infusion of 0.3 mg.kg-1.h-1 for 15 min and a maintenance infusion of 0.065 mg.kg-1.h-1. Increments of alfentanil were given whenever heart rate or systolic blood pressure exceeded pre-induction values by more than 10%. During anaesthesia mean arterial pressure and heart rate were similar in both groups and there was no difference in alfentanil requirement. An immediate increase in blood glucose concentrations was seen following incision, but maximum concentrations were measured in the early postoperative period. Serum cortisol concentrations decreased after induction of anaesthesia. During surgery they returned to pre-induction values, and in the postoperative period they increased to about twice the pre-induction values. It is concluded that midazolam/alfentanil anaesthesia is as effective as anaesthesia induced by thiopentone, alfentanil and nitrous oxide in suppressing the stress-response to surgery until the postoperative period. No signs of prolonged adrenocortical depression were observed.

Epidural sufentanil for intra- and postoperative analgesia in thoracic surgery: a comparative study with intravenous sufentanil

A comparative study was undertaken to evaluate the effectiveness of epidural sufentanil in providing intra- and postoperative analgesia during thoracic surgery. Sufentanil was chosen on the basis of its high lipid solubility and its potent opiate receptor binding. Epidural sufentanil was compared with intravenous sufentanil as the major intraoperative analgetic agent in an anesthesia regimen with midazolam and nitrous oxide. Epidural sufentanil significantly decreased the need for supplementary intravenous analgesia. In the epidural sufentanil group the immediate postoperative analgesia was found to be better, with a longer duration of action, compared with the intravenous sufentanil group. Postoperatively epidural sufentanil was compared with epidural morphine. Sufentanil provided good analgesia with a very fast onset and a mean duration of almost 7 h. Severe respiratory depression was observed in one patient within 1 h of extubation, probably due to the combined effects of the narcotic administration and residual midazolam. It is concluded that 50 micrograms of sufentanil administered in the thoracic epidural space provides valuable intraoperative analgesia which can easily be extended into the postoperative period, although all necessary precautions for epidural opiate administration should be taken.

Opioid receptor systems and the endorphins: a review of their spinal organization

A review of the spinal organization of opioid receptor systems and endorphins is presented. The review is a consideration of the physiological mechanisms underlying the effect of spinal opioids, the pharmacology of the opioid receptors that moderate a variety of spinal processing systems, and the endorphin systems that act upon the spinal receptors.

Stress and the pituitary-adrenal axis

The hypothalamo-pituitary-adrenal axis is controlled by complex regulatory mechanisms. Numerous factors such as CRF, vasopressin, oxytocin, angiotensin II and conceivably other hormones--all controlled by various substances acting on central locations--stimulate the release of the stress hormone ACTH. On the other hand, glucocorticoids inhibit the secretion of ACTH by acting at the hypothalamic and/or pituitary level. The release of ACTH is therefore the final outcome of the interactions between the hypothalamus, the adrenal gland and possibly other organs. The multimolecular nature of the factors responsible for the control of the pituitary-adrenal axis is an attractive hypothesis because of the great variety of stress stimuli. The various factors could have specific roles in various stress situations. They provide a highly sensitive mechanism regulating very finely the stress hormone in response to a whole variety of endogenous and exogenous stimuli. Depending on the type of stress, they may therefore singly or in combination affect the amount and duration of ACTH and steroid secretion. The released glucocorticoids may then produce their numerous effects on inflammatory and immunological processes, carbohydrate metabolism, shock and water balance. It has been postulated that these effects may be important in order to prevent host responses from over-reacting to stress and threatening homeostasis. However, proof of the necessity of the glucocorticoid hypersecretion in response to stress remains elusive.

Influence of induction of anaesthesia with midazolam on the neuro-endocrine response to surgery

The effect of midazolam, for induction of anaesthesia, on the glycaemic and adrenocortical responses to lower pelvic surgery in female patients has been studied and compared with a comparable group of patients receiving thiopentone. Although midazolam has been shown to obtund adrenaline and noradrenaline release to electrical or surgical stress in the rat and dog, there was no blunting of the glycaemic response to surgery in man. Plasma cortisol levels in response to surgery and anaesthesia were comparable in the two groups of patients.

Epidural diamorphine and the metabolic response to upper abdominal surgery

The effect of the administration of diamorphine 10 mg epidurally on the metabolic response to cholecystectomy was investigated and compared with a control group of patients given intravenous papaveretum. There were no significant differences in blood glucose, lactate and pyruvate, and plasma nonesterified fatty acid values between the epidural diamorphine group and the control group. Plasma cortisol concentrations were significantly lower in the epidural diamorphine group postoperatively and this was associated with a marked improvement in pain relief. We conclude that epidural opiates do not directly influence the metabolic response to surgery, but decrease the cortisol response postoperatively secondary to improved analgesia.

Epidural fentanyl counteracts sympathetic gastric inhibition

Postoperative paralytic ileus is in part mediated by the sympathetic gastrointestino-gastrointestinal (GI-GI) reflex. The modulation of this reflex by epidural fentanyl (50 micrograms) was studied in chloralose-anesthetized, ventilated cats. The vagi were cut in the neck but could be efferently stimulated. Gastric volume, arterial pressure and heart rate were followed and the GI-GI reflex was elicited by intestinal distension, mesenteric afferent nerve stimulation or heating or capsaicin administered intra-arterially to an intestinal loop. Epidural fentanyl enhanced the gastric contraction response to efferent vagal stimulation and considerably counter-acted the GI-GI reflex inhibition of vagally induced tone. These effects were reversed by epidural naloxone (10 micrograms). In contrast, 50 micrograms of fentanyl i.v. only enhanced the effect of vagal stimulation but had no influence on the inhibitory GI-GI reflex responses. Apparently, epidural fentanyl may inhibit the GI-GI reflex by a spinal point of action.