Effects of epidural anaesthesia on intestinal oxygenation in pigs

Effect of Cranial Flexion of Pelvic Limbs on Interlaminar Length of the Lumbosacral Space in Sternally and Laterally Recumbent Juvenile Duroc and Adult Yucatan Pigs

Epidural puncture in swine is technically challenging. Several combinations of limb and body positions have been suggested to increase lumbosacral interlaminar space (LSS) and lumbosacral angle (LSA). This study investigated whether cranial hyperflexion of pelvic limbs increased LSS and LSA in laterally and sternally recumbent juvenile Duroc and adult Yucatan pigs and assessed which position produced the largest LSS. Juvenile Duroc (n = 7) and adult Yucatan (n = 7) pigs were euthanized and randomly placed in 4 positions: sternal with neutral limbs, sternal with cranially hyperflexed limbs, lateral with neutral limbs, and lateral with hyperflexed limbs. LSS and LSA were measured on transverse axial CT images of the spine and compared by using multivariate ANOVA and the Student t test. In both age groups, LSS was greater in lateral flexed (juvenile, 7.0 ± 0.7 mm; adult, 15.9 ± 1.1 mm) and sternal flexed (juvenile, 7.5 ± 1 mm; adult, 17.1 ± 1.1 mm) positions than in lateral neutral (juvenile, 5.4 ± 0.9 mm; adult, 9.6 ± 1.6 mm) position. In addition, in both age groups, LSS and LSA in lateral neutral position were smaller than lateral flexed, sternal neutral, and sternal flexed positions. In adults, LSS was greater in lateral flexed and sternal flexed than in sternal neutral position. Hyperflexion of pelvic limbs increases LSS and LSA in sternally recumbent adult Yucatan pigs and laterally recumbent adult Yucatan and juvenile Duroc swine. Increased LSS from positioning pigs with pelvic limbs flexed in sternal or lateral recumbence may facilitate epidural puncture compared with neutral limb positioning.

Effects of Thoracic Epidural Anaesthesia on the Serosal Microcirculation of the Human Small Intestine

BACKGROUND

The effect of thoracic epidural analgesia (TEA) on splanchnic blood flow during abdominal surgery remains unclear. The purpose of this study was to examine whether the hemodynamic effects of TEA resulted in microcirculatory alterations to the intestinal serosa, which was visualized using incident dark-field (IDF) videomicroscopy.

METHODS

An observational cohort study was performed. In 18 patients, the microcirculation of the intestinal serosa was visualized with IDF. Microcirculatory and hemodynamic measurements were performed prior to (T1) and after administering a bolus of levobupivacaine (T2). If correction of blood pressure was indicated, a third measurement was performed (T3). The following microcirculatory parameters were calculated: microvascular flow index, proportion of perfused vessels, perfused vessel density and total vessel density. Data are presented as median [IQR].

RESULTS

Mean arterial pressure decreased from 73 mmHg (68-83) at T1 to 63 mmHg (±11) at T2 (p = 0.001) with a systolic blood pressure of 114 mmHg (98-128) and 87 (81-97), respectively (p = 0.001). The microcirculatory parameters of the bowel serosa, however, were unaltered. In seven patients, blood pressure was corrected to baseline values from a MAP of 56 mmHg (55-57), while microcirculatory parameters remained constant.

CONCLUSION

We examined the effects of TEA on the intestinal serosal microcirculation during abdominal surgery using IDF imaging for the first time in patients. Regardless of a marked decrease in hemodynamics, microcirculatory parameters of the bowel serosa were not significantly affected.

TRIAL REGISTRY NUMBER

ClinicalTrials.gov identifier NCT02688946.

Thoracic epidural analgesia reduces gastric microcirculation in the pig

Background

Thoracic epidural analgesia (TEA) is used for pain relief during and after abdominal surgery, but the effect of TEA on the splanchnic microcirculation remains debated. We evaluated whether TEA affects splanchnic microcirculation in the pig.

Methods

Splanchnic microcirculation was assessed in nine pigs prior to and 15 and 30 min after induction of TEA. Regional blood flow was assessed by neutron activated microspheres and changes in microcirculation by laser speckle contrast imaging (LSCI).

Results

As assessed by LSCI 15 min following TEA, gastric arteriolar flow decreased by 22 % at the antrum (p = 0.020) and by 19 % at the corpus (p = 0.029) of the stomach. In parallel, the microcirculation decreased by 19 % at the antrum (p = 0.015) and by 20 % at the corpus (p = 0.028). Reduced arteriolar flow and microcirculation at the antrum was confirmed by a reduction in microsphere assessed regional blood flow 30 min following induction of TEA (p = 0.048). These manifestations took place along with a drop in systolic blood pressure (p = 0.030), but with no significant change in mean arterial pressure, cardiac output, or heart rate.

Conclusion

The results indicate that TEA may have an adverse effect on gastric arteriolar blood flow and microcirculation. LSCI is a non-touch technique and displays changes in blood flow in real-time and may be important for further evaluation of the concern regarding the effect of thoracic epidural anesthesia on gastric microcirculation in humans.

Trial registrations

Not applicable, non-human study.

Thoracic epidural anesthesia with ropivacaine does not compromise the tolerance of acute normovolemic anemia in pigs

BACKGROUND

The initial treatment of an acute blood loss with acellular fluids leads to the dilution of the red cell mass remaining in the vasculature, that is, to acute normovolemic anemia. Whether the compensation and, thus, the tolerance of acute anemia, are affected by sympathetic block induced by thoracic epidural anesthesia has not yet been investigated.

METHODS

Eighteen anesthetized and mechanically ventilated pigs were instrumented with thoracic epidural catheters and randomly assigned to receive an epidural injection of either 5-ml ropivacaine 0.2% (n = 9) aiming for a Th5-Th10 block or saline (n = 9) followed by continuous epidural infusion of 5 ml/h of either fluid. Subsequently, acute normovolemic anemia was induced by replacement of whole blood with 6% hydroxyethyl starch solution until a "critical" limitation of oxygen transport capacity was reached as indicated by a sudden decrease in oxygen consumption. The critical hemoglobin concentration quantified at this time point was the primary endpoint; secondary endpoints were hemodynamic and oxygen transport parameters.

RESULTS

Thoracic epidural anesthesia elicited only a moderate decrease in mean arterial pressure and cardiac index and a transient decrease in oxygen extraction ratio. During progressive anemia, the compensatory increases in cardiac index and oxygen extraction ratio were not compromised by thoracic epidural anesthesia. Critical hemoglobin concentration was reached at identical levels in both groups (ropivacaine group: 2.5 ± 0.6 g/dl, saline group: 2.5 ± 0.6 g/dl).

CONCLUSION

Thoracic epidural anesthesia with ropivacaine 0.2% does not decrease the tolerance to acute normovolemic anemia in healthy pigs. The hemodynamic compensation of acute anemia is fully preserved despite sympathetic block, and the critical hemoglobin concentration remains unaffected.

Effect of thoracic epidural anaesthesia on splanchnic blood flow

BACKGROUND

Thoracic epidural anaesthesia (TEA) is used widely in colorectal surgery. However, there is increasing concern that epidurals are associated with postoperative hypotension, mediating a potential reduction in splanchnic flow. The aim was to review the literature on the effects of TEA on splanchnic blood flow.

METHODS

PubMed and Cochrane databases were searched. Search terms used were: English language, 'thoracic epidural splanchnic flow', 'thoracic epidural gut blood flow', 'thoracic epidural intestinal blood flow' and 'thoracic epidural colonic blood flow'. Abstracts were reviewed by two independent researchers and irrelevant studies excluded. The full text of the remaining articles was then retrieved.

RESULTS

Twenty-two abstracts were reviewed and three excluded. Nineteen papers were reviewed in full and seven irrelevant articles excluded. Five human studies investigated the effects of TEA on splanchnic flow. Two studies measured splanchnic flow directly and found an epidural-mediated fall in flow, unresponsive to intravenous fluids and requiring vasopressors or inotropes to restore baseline flow. The remaining three studies had inconsistent findings and haemodynamic stability was maintained. The seven animal studies identified were heterogeneous in both methodology and findings. Three suggested a protective role for thoracic epidurals in septic shock and pancreatitis.

CONCLUSION

These findings are inconsistent; however, the two studies that investigated the effects of vasoconstrictors on splanchnic blood flow directly both found a significant epidural-mediated reduction in splanchnic blood flow that was unresponsive to fluid therapy.

[Nonanalgesic effects of thoracic epidural anesthesia]

Thoracic epidural anesthesia, which has been performed since the 1950s, has progressed from being one analgesic technique among others to its present status as the technique of choice for managing pain after major abdominal and thoracic surgery. In addition to providing effective analgesia, the epidural infusion of local anesthetic agents produces a sympathetic block that offers advantages over other types of pain control, particularly with respect to the cardiovascular, respiratory, and gastrointestinal systems. Thoracic epidural anesthesia provides dynamic pain relief, allowing the patient to resume activity early. It also permits early extubation and is associated with fewer postoperative pulmonary complications, shorter duration of paralytic ileus, and a better response to the stress of anesthesia and surgery. However, meta-analyses have not yet demonstrated that postoperative outcomes are improved. This review describes the nonanalgesic effects of thoracic epidural anesthesia.

The neuronal guidance protein netrin-1 reduces alveolar inflammation in a porcine model of acute lung injury

Introduction

Acute lung injury (ALI) is an inflammatory disorder of pulmonary or extrapulmonary origin. We have previously demonstrated that netrin-1 dampens murine ALI, and in an attempt to advance this finding into future clinical practice we evaluated whether netrin-1 would reduce alveolar inflammation during porcine ALI.

Methods

This was a controlled in vivo experimental study in pigs. We induced ALI through lipoploysaccharide (LPS) infusion (50 μg/kg) for 2 hours. Following this, we exposed animals to either vehicle, intravenous netrin-1 (netrin-1 i.v.) or inhaled netrin-1 (netrin-1 inh.). Serum samples and bronchoalveolar lavage (BAL) were obtained to determine levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, interleukin-6 and interleukin-8 at baseline and 6 hours following treatment. Myeloperoxidase activity (MPO) and protein levels were determined in the BAL, and tissue samples were obtained for histological evaluation. Finally, animals were scanned with spiral CT.

Results

Following LPS infusion, animals developed acute pulmonary injury. Serum levels of TNF-α and IL-6 were significantly reduced in the netrin-1 i.v. group. BAL demonstrated significantly reduced cytokine levels 6 hours post-netrin-1 treatment (TNF-α: vehicle 633 ± 172 pg/ml, netrin-1 i.v. 84 ± 5 pg/ml, netrin-1 inh. 168 ± 74 pg/ml; both P < 0.05). MPO activity and protein content were significantly reduced in BAL samples from netrin-1-treated animals. Histological sections confirmed reduced inflammatory changes in the netrin-1-treated animals. Computed tomography corroborated reduced pulmonary damage in both netrin-1-treated groups.

Conclusions

We conclude that treatment with the endogenous anti-inflammatory protein netrin-1 reduces pulmonary inflammation during the initial stages of ALI and should be pursued as a future therapeutic option.

Intestinal effects of thoracic epidural anesthesia

PURPOSE OF REVIEW

Thoracic epidural anesthesia (TEA) is most frequently used after major surgery. However, despite ongoing research, the influence of TEA on the intestinal perioperative pathophysiology is not fully understood.

RECENT FINDINGS

According to recent results, the splanchnic sympathetic activity is reduced during TEA both in animal models and in clinical TEA. The splanchnic sympathetic activity during high TEA is still unknown. Intestinal perfusion effects of TEA are still unclear as the technique and extent of TEA, hemodynamic alteration and size of measurement result in--seemingly--conflicting reports. Postoperative ileus after laparotomy is ameliorated by TEA. Recent findings suggest beneficial effects also after major laparoscopic procedures. Finally, the impact of TEA on the intestinal pathophysiology in critical illness is an area of growing clinical and scientific interest, although this knowledge is just at its beginning.

SUMMARY

Further research concerning the use of TEA in major laparoscopic procedures and its potential to improve or endanger anastomotic healing is warranted. The experimental studies of TEA in critical illness should be expanded.

Effects of thoracic epidural anesthesia on hemodynamics and global oxygen transport in ovine endotoxemia

Besides providing effective analgesia, thoracic epidural anesthesia (TEA) has been shown to decrease perioperative morbidity and mortality. Because of its vasodilatory properties in association with the sympathetic blockade, however, TEA may potentially aggravate cardiovascular dysfunctions resulting from sepsis and systemic inflammatory response syndrome. The objective of the present study was to assess the effects of TEA on hemodynamics, global oxygen transport, and renal function in ovine endotoxemia. After a baseline measurement in healthy sheep (n = 18), Salmonella typhosa endotoxin was centrally infused at incremental doses to induce and maintain a hypotensive-hypodynamic circulation using an established protocol. The animals were then randomly assigned to one of two groups. In the treatment group, continuous TEA was initiated with 0.1 mL.kg of 0.125% bupivacaine at the onset of endotoxemia and maintained with 0.1 mL.kg.h. In the control group, the same amount of isotonic sodium chloride solution was injected through the epidural catheter. In the animals surviving the entire experiment (n = 7 per group), cardiac index and mean arterial pressure decreased in a dose-dependent manner during endotoxin infusion. In the TEA group, neither systemic hemodynamics nor global oxygen transport were impaired beyond the changes caused by endotoxemia itself. Urinary output was increased in the TEA group as compared with the control group (P < 0.05). In this model of endotoxic shock, TEA improved renal perfusion without affecting cardiopulmonary hemodynamics and global oxygen transport.

Epidural anaesthesia and analgesia for surgery: still going strong?

PURPOSE OF REVIEW

The discussion on the value of epidural anaesthesia and analgesia for surgery is fuelled by current controversies regarding effects on postoperative morbidity and mortality, potential benefits for outcome and the fear of rare, but catastrophic neurological complications. This review of the most recent publications on the topic since April 2002 illustrates some of the aspects contributing to the ongoing discussion.

RECENT FINDINGS

In contradiction to previous meta-analyses, recent trials could not demonstrate significant improvements of overall morbidity or mortality by epidural anaesthesia and analgesia. However, the technique was shown again to provide superior analgesia and a reduction of perioperative stress response and respiratory complications. Analysis of the current literature strongly supports that epidural anaesthesia and analgesia remains a safe practice with a low rate of severe complications, in particular in paediatric surgery. Several developments in equipment, techniques and especially drugs have been reported, resulting in improved balanced anaesthesia and analgesia and contributing to the safety of this technique.

SUMMARY

In an era of evidence-based medicine, further meta-analyses and well-planned large randomized trials have to address the controversial issues of epidural anaesthesia and analgesia and postoperative outcome. In the context of a more holistic 'rehabilitative' management of the perioperative period, this technique might well represent a key factor to improve outcome, reduce hospital stay and thereby healthcare costs. Recent innovations and developments in techniques and drugs as well as established guidelines should further minimize potential errors and harmful complications.

Effects of systemically applied clonidine on intestinal perfusion and oxygenation in healthy pigs during general anaesthesia and laparotomy 1

BACKGROUND AND OBJECTIVE

Clonidine, which is used for induction of sympatholysis and prevention or treatment of alcohol withdrawal in anaesthesia and intensive care medicine, may have deleterious effects on intestinal mucosal perfusion. This study was designed to investigate the effects of clonidine on intestinal perfusion and oxygenation.

METHODS

Following ethical approval 17 anaesthetized, and acutely instrumented pigs were randomly assigned to two groups: eight animals received intravenous clonidine (2 microg kg(-1) bolus and 2 microg kg(-1) h(-1)), nine animals served as a control group. Measurement points for systemic and regional haemodynamic and oxygenation parameters were 135 and 315 min after starting the clonidine application.

RESULTS

Clonidine elicited systemic haemodynamic changes (median [25-75th interquartile range]): heart rate (106 [91, 126] to 84 [71, 90] beats min(-1)) cardiac output (147 [123, 193] to 90 [87, 107] mL min(-1) kg(-1)) and mean arterial pressure (77 [72, 93] to 69 [61, 78] mmHg) decreased. Despite systemic haemodynamic changes, the superior mesenteric artery blood flow did not change in the clonidine group. The vascular resistance of the superior mesenteric artery decreased. The small intestinal oxygen supply, the mucosal and the serosal tissue oxygen partial pressure did not change.

CONCLUSIONS

Systemic sympatholysis induced by intravenously applied clonidine in addition to basic intravenous anaesthesia elicited a decrease in cardiac output and mean arterial pressure. However, regional macrohaemodynamic perfusion was maintained and intestinal oxygenation did not change. Clonidine does not impair intestinal mucosal and serosal oxygenation under physiological conditions.

Evaluation of Sympathetic Blockade after Intrathecal and Epidural Lidocaine in Rats by Laser Doppler Perfusion Imaging

The widespread use of neuraxial anaesthesia increases the need for animal models to evaluate therapeutic prospects, mechanisms and risks of this technique. As a methodological prerequisite, we characterised the sympathetic blockade after different modes of neuraxial anaesthesia with regard to segments supplying the splanchnic region. Under haemodynamic monitoring, lidocaine 2% or saline were infused via intrathecal (10 microl), lumbar epidural (10 and 30 microl) or thoracic epidural (10 and 30 microl) catheters. Segmental spread of neuraxially infused local anaesthetic was assessed using methylene blue. Mean arterial blood pressure decreased more severely after neuraxial lidocaine in thoracic epidural (10 and 30 microl) compared to high-volume (30 microl anaesthesia animals. Determination of the sympathetic blockade by means of laser Doppler perfusion imaging was restricted to the paws due to a higher density of subcutaneous blood vessels as compared to the abdominal wall (mean +/- SD: 3.93 +/- 0.06 vs. 1.35 +/- 0.05/384 mm(2), p < 0.05). Only high-volume (30 microl) lumbar and thoracic epidural anaesthesia (10 and 30 microl) increased skin perfusion in both hind and front paws. This extensive sympathetic blockade was demonstrated to include splanchnic segments using thermography. Segmental spread of methylene blue did not closely correspond to laser Doppler findings and should be interpreted as minimum rather than exact epidural spread of local anaesthetic.

Non-analgetic effects of thoracic epidural anaesthesia

PURPOSE OF REVIEW

This review presents a brief overview of the non-analgetic effects of thoracic epidural anaesthesia. It covers the cardiac, pulmonary and gastrointestinal effects of thoracic epidural anaesthesia. The results of newer studies are of particular importance regarding mortality and major morbidity after thoracic epidural anaesthesia.

RECENT FINDINGS

The clinical effects of thoracic epidural anaesthesia are mainly attributed to a transient thoracic sympathetic block affecting different organs. Furthermore, local anaesthetic itself reabsorbed from the epidural space may contribute to the non-analgetic effects of thoracic epidural anaesthesia. Experimental studies have suggested that thoracic epidural anaesthesia may attenuate the perioperative stress response after major surgery. The possible beneficial mechanisms of action include an improvement of left ventricular function by direct anti-ischaemic effects, a reduction in cardiovascular complications, an advance on gastrointestinal function, and a reduction in pulmonary complications, as well as a positive impact on the coagulation system and the postoperative inflammatory response. However, it is questionable whether these effects of thoracic epidural anaesthesia may lead to an improved perioperative outcome after major surgery. Recent studies have suggested that, despite the superior quality of pain relief and better quality of life, thoracic epidural anaesthesia does not reduce mortality and major morbidity, especially after major abdominal and cardiac surgery.

SUMMARY

Despite this controversy, the numerous positive effects and advantages of thoracic epidural anaesthesia are the reasons for its increasing popularity. However, the advantages of thoracic epidural anaesthesia must be incorporated into a multimodal treatment management aimed at improving outcomes after surgery.

Effects of xenon anaesthesia on intestinal oxygenation in acutely instrumented pigs

BACKGROUND

Xenon is a narcotic gas that might be able to replace volatile anaesthetics or nitrous oxide due to its favourable pharmacological properties, such as providing haemodynamic stability. Intestinal oxygenation is affected by most volatile anaesthetics as a result of cardiodepressive effects. Reducing oxygenation of the gut might be a factor leading to perioperative organ dysfunction. This animal study was designed to assess the effects of xenon on intestinal oxygenation.

METHODS

After ethical approval, 24 anaesthetized, acutely instrumented pigs were randomly assigned to three groups: nine animals received xenon anaesthesia with inspiratory concentrations of 0, 20, 50 and 65% in addition to their basic i.v. anaesthesia, nine animals served as a study control group, and five animals were used to assess model stability. Measurement of systemic and regional haemodynamic and oxygenation parameters was made 30 min after changing the xenon concentration.

RESULTS

Xenon elicited dose-dependent systemic haemodynamic changes: heart rate and cardiac output decreased by 30%, while mean arterial pressure was stable. Superior mesenteric artery blood flow was lower in the xenon group. Vascular resistance of the superior mesenteric artery increased. The small intestinal oxygen supply decreased with increasing xenon concentration; the mucosal tissue oxygen partial pressure decreased but did not reach hypoxic (<5 mm Hg) values. Serosal tissue oxygen partial pressure was maintained.

CONCLUSIONS

Xenon, in addition to basic i.v. anaesthesia, elicited a decrease in cardiac output and maintained mean arterial pressure. Intestinal oxygenation was maintained, although regional macrohaemodynamic perfusion decreased. Xenon does not impair intestinal oxygenation under physiological conditions.

Effects of thoracic epidural anaesthesia on intestinal microvascular perfusion in a rodent model of normotensive endotoxaemia

OBJECTIVE

To investigate whether sympathetic blockade by means of thoracic epidural anaesthesia (TEA) increases intestinal perfusion during normotensive endotoxaemia.

DESIGN

A prospective, randomised and controlled animal study.

SETTING

Animal laboratory in a university hospital.

SUBJECTS

Sprague-Dawley male rats.

INTERVENTIONS

The rats were anaesthetised with urethane and ketamine, mechanically ventilated and haemodynamically monitored. Lidocaine or saline were infused continuously via thoracic epidural catheters followed by a continuous intravenous infusion of Escherichia coli lipopolysaccharide (1.5 mg/kg per h). Densities of perfused and non-perfused capillaries (i.e., with and without erythrocyte perfusion, respectively) as well as erythrocyte velocity in both the mucosa and the muscularis of the terminal ileum were determined using intravital microscopy.

MEASUREMENTS AND RESULTS

Measurements were performed at baseline, after 30 min of epidural infusion as well as after 60 and 120 min of lipopolysaccharide infusion. In animals receiving TEA, mean arterial pressure and heart rate were significantly reduced throughout the experiment. In the muscularis the endotoxaemia-induced increase in non-perfused capillaries was absent with epidural lidocaine (0 [0/0] versus 39 [36/137] cm(-1), median [25(th)/75(th) percentile]), whereas in the mucosa perfused capillary density declined to a greater extent than in controls (-47 [-53/-23]%) versus -19 [-34/+10]%, p<0.05). Erythrocyte velocity decreased with endotoxaemia and was not influenced by epidural lidocaine.

CONCLUSIONS

Microvascular perfusion data during endotoxaemia show a redistribution of blood flow towards the mucosa. TEA seems to impede this redistribution resulting in improved muscularis and worsened mucosal microvascular perfusion.

Effects of thoracic epidural anaesthesia on microvascular gastric mucosal oxygenation in physiological and compromised circulatory conditions in dogs

BACKGROUND

The effects of thoracic epidural anaesthesia (TEA) on gastric mucosal microvascular haemoglobin oxygenation (microHbO(2)) are unclear. At the splanchnic level, reduction of sympathetic tone may promote vasodilation and increase microHbO(2). However, these splanchnic effects are counteracted by systemic effects of TEA (e.g., decreased cardiac output (CO) and mean arterial pressure (MAP)), thus making the net effect on microHbO(2) difficult to predict. In this respect, effects of TEA on microHbO(2) may differ between physiological and compromised circulatory conditions, and additionally may depend on adequate fluid resuscitation. Furthermore, TEA may alter the relationship between regional microHbO(2) and systemic oxygen-transport (DO(2)).

METHODS

Chronically instrumented dogs (flow probes for CO measurement) were anaesthetized, their lungs ventilated and randomly received TEA with lidocaine (n=6) or epidural saline (controls, n=6). Animals were studied under physiological and compromised circulatory conditions (PEEP 10 cm H(2)O), both with and without fluid resuscitation. We measured gastric mucosal microHbO(2) by reflectance spectrophotometry, systemic DO(2), and systemic haemodynamics (CO, MAP).

RESULTS

Under physiological conditions, TEA preserved microHbO(2) (47 (3)% and 49 (5)%, mean (sem)) despite significantly decreasing DO(2) (11.3 (0.8) to 10.0 (0.7) ml kg(-1) min(-1)) and MAP (66 (2) to 59 (3) mm Hg). However, during compromised circulatory conditions, TEA aggravated the reduction in microHbO(2) (to 32 (1)%), DO(2) (to 6.7 (0.8) ml kg(-1) min(-1)) and MAP (to 52 (4) mm Hg), compared with controls. During TEA, fluid resuscitation completely restored these variables. TEA preserved the correlation between microHbO(2) and DO(2), compared with controls.

CONCLUSIONS

TEA maintains microHbO(2) under physiological conditions, but aggravates the reduction of microHbO(2) induced by cardiocirculatory depression, thereby preserving the relationship between gastric mucosal and systemic oxygenation.