Antioxidative vitamin treatment: effect on lipid peroxidation and limb swelling after revascularization operations

Mechanisms and Interventions on Acute Lower Limb Ischemia/Reperfusion Injury: A Review and Insights from Cell to Clinical Investigations

AIM

This review aims to highlight mechanistic insights on skeletal muscle ischemia/reperfusion injury (IRI), a potentially life-threatening complication after acute lower limb ischemia. Lower limb IRI produces a wide spectrum of manifestations, ranging from local skeletal muscle necrosis to multi-organ failure. There is increasing evidence from both in vitro and in vivo reports to demonstrate several promising interventions that have successfully reduced IRI in skeletal muscle ischemic models. However, clinical studies to confirm their benefits are still lacking.

METHOD

We conducted a comprehensive search of English literature listed in the PubMed database (All related published articles shown in PubMed until September 2020 have been included in this review), using the following keywords: acute limb ischemia, acute arterial occlusion, compartment syndrome, ischemic reperfusion injury, revascularization and hypoxic reoxygenation.

RESULT

58 articles pertinent to acute limb ischemia models were identified. The underlying mechanisms associated with IRI in skeletal muscle are due to excessive mitochondrial production of reactive oxygen species (ROS), cellular apoptosis and activation of inflammatory cascades. Several therapeutic interventions including both pharmacological and non-pharmacological treatments have been investigated and some showed promising results. These interventions include antioxidation, anti-inflammation, anti-hypertension, controlled-reperfusion and ischemic preconditioning. Further clinical studies are needed to warrant their use in a clinical setting for lower limb IRI treatment.

CONCLUSION

This review comprehensively summarizes the mechanisms underlying IRI in lower limb ischemia. The reports currently available regarding the potential therapeutic interventions against lower limb IRI from in vitro, in vivo and clinical studies are presented and discussed. These findings may provide mechanistic insights for devising the strategies to improve the clinical outcomes in IRI patients in the near future. Further clinical studies are needed to warrant their use in a clinical setting for lower limb IRI treatment.

The Use of Transcutaneous Electrical Stimulation of the Calf in Patients Undergoing Infrainguinal Bypass Surgery

BACKGROUND

Infrainguinal bypass surgery is frequently associated with postoperative reperfusion edema of the limb. The etiology is thought to be multifactorial, and there is as yet no standardized treatment protocol for this problem. The primary aim of this study was to assess whether the use of intermittent electrical stimulation of the calf muscles after infrainguinal bypass surgery was effective in reducing the incidence of edema, and the secondary aims to determine the effect of calf muscle stimulation on arterial and venous flow in the operated leg.

METHODS

Forty patients due to undergo infrainguinal bypass surgery for critical lower-limb ischemia (Fontaine grading III-IV or Rutherford grading II-III) were recruited prospectively and randomly divided into the control group, who received the current standard of care, and study group, who received electrical calf muscle stimulation for a 1 hour session twice daily for the first postoperative week. Preoperatively and postoperatively, the leg was measured at 3 predetermined points and a duplex ultrasound scan performed.

RESULTS

The groups were well matched for all parameters. At 1 week, the below knee and calf girth were less in the study group (P = 0.025 and P = 0.043, respectively). Venous flow volumes at rest and on stimulation were higher in the study group (P = 0.010 and P = 0.029, respectively). At 6 weeks, the below knee girth and amount of pitting edema were less in the study group (P = 0.011 and P = 0.014, respectively).

CONCLUSIONS

We conclude that transcutaneous electrical stimulation of the calf decreased lower-limb swelling at 1 and 6 weeks, and increased the venous flow volume at rest and on stimulation at 1 week in patients undergoing infrainguinal bypass surgery for critical ischemia regardless of patient factors or the type of bypass surgery performed or graft used.

The effectiveness of antioxidant vitamins C and E in reducing myocardial infarct size in patients subjected to percutaneous coronary angioplasty (PREVEC Trial): study protocol for a pilot randomized double-blind controlled trial

BACKGROUND

Acute myocardial infarction (AMI) is the leading cause of mortality worldwide. Oxidative stress has been involved in the ischemia-reperfusion injury in AMI. It has been suggested that reperfusion accounts for up to 50% of the final size of a myocardial infarct, a part of the damage likely to be prevented.Therefore, we propose that antioxidant reinforcement through vitamins C and E supplementation should protect against the ischemia-reperfusion damage, thus decreasing infarct size.The PREVEC Trial (Prevention of reperfusion damage associated with percutaneous coronary angioplasty following acute myocardial infarction) seeks to evaluate whether antioxidant vitamins C and E reduce infarct size in patients subjected to percutaneous coronary angioplasty after AMI.

METHODS/DESIGN

This is a randomized, 1:1, double-blind, placebo-controlled clinical trial.The study takes place at two centers in Chile: University of Chile Clinical Hospital and San Borja Arriarán Clinical Hospital.The subjects will be 134 adults with acute myocardial infarction with indication for percutaneous coronary angioplasty.This intervention is being performed as a pilot study, involving high-dose vitamin C infusion plus oral administration of vitamin E (Vitamin-treatment group) or placebo (Control group) during the angioplasty procedure. Afterward, the Vitamin-treatment group receives oral doses of vitamins C and E, and the Control group receives placebo for 84 days after coronary angioplasty.Primary outcome is infarct size, assessed by cardiac magnetic resonance (CMR), measured 6 and 84 days after coronary angioplasty.Secondary outcomes are ejection fraction, measured 6 and 84 days after coronary angioplasty with CMR, and biomarkers for oxidative stress, antioxidant status, heart damage, and inflammation, which will be measured at baseline, at the onset of reperfusion, 6 to 8 hours after revascularization, and at hospital discharge.

DISCUSSION

The ischemia-reperfusion event occurring during angioplasty is known to increase myocardial infarct size. The cardioprotective benefits of high doses of vitamin C combined with vitamin E have not been fully explored. The PREVEC Trial seeks to determine the suitability of the therapeutic use of vitamins C and E against the reperfusion damage produced during angioplasty.Patient recruitment opened in February 2013. The trial is scheduled to end in March 2016.

TRIAL REGISTRATION

ISRCTN56034553.

Molecular basis of cardioprotective effect of antioxidant vitamins in myocardial infarction

Acute myocardial infarction (AMI) is the leading cause of mortality worldwide. Major advances in the treatment of acute coronary syndromes and myocardial infarction, using cardiologic interventions, such as thrombolysis or percutaneous coronary angioplasty (PCA) have improved the clinical outcome of patients. Nevertheless, as a consequence of these procedures, the ischemic zone is reperfused, giving rise to a lethal reperfusion event accompanied by increased production of reactive oxygen species (oxidative stress). These reactive species attack biomolecules such as lipids, DNA, and proteins enhancing the previously established tissue damage, as well as triggering cell death pathways. Studies on animal models of AMI suggest that lethal reperfusion accounts for up to 50% of the final size of a myocardial infarct, a part of the damage likely to be prevented. Although a number of strategies have been aimed at to ameliorate lethal reperfusion injury, up to date the beneficial effects in clinical settings have been disappointing. The use of antioxidant vitamins could be a suitable strategy with this purpose. In this review, we propose a systematic approach to the molecular basis of the cardioprotective effect of antioxidant vitamins in myocardial ischemia-reperfusion injury that could offer a novel therapeutic opportunity against this oxidative tissue damage.

Cardioprotection against ischaemia/reperfusion by vitamins C and E plus n-3 fatty acids: molecular mechanisms and potential clinical applications

The role of oxidative stress in ischaemic heart disease has been thoroughly investigated in humans. Increased levels of ROS (reactive oxygen species) and RNS (reactive nitrogen species) have been demonstrated during ischaemia and post-ischaemic reperfusion in humans. Depending on their concentrations, these reactive species can act either as benevolent molecules that promote cell survival (at low-to-moderate concentrations) or can induce irreversible cellular damage and death (at high concentrations). Although high ROS levels can induce NF-κB (nuclear factor κB) activation, inflammation, apoptosis or necrosis, low-to-moderate levels can enhance the antioxidant response, via Nrf2 (nuclear factor-erythroid 2-related factor 2) activation. However, a clear definition of these concentration thresholds remains to be established. Although a number of experimental studies have demonstrated that oxidative stress plays a major role in heart ischaemia/reperfusion pathophysiology, controlled clinical trials have failed to prove the efficacy of antioxidants in acute or long-term treatments of ischaemic heart disease. Oral doses of vitamin C are not sufficient to promote ROS scavenging and only down-regulate their production via NADPH oxidase, a biological effect shared by vitamin E to abrogate oxidative stress. However, infusion of vitamin C at doses high enough to achieve plasma levels of 10 mmol/l should prevent superoxide production and the pathophysiological cascade of deleterious heart effects. In turn, n-3 PUFA (polyunsaturated fatty acid) exposure leads to enhanced activity of antioxidant enzymes. In the present review, we present evidence to support the molecular basis for a novel pharmacological strategy using these antioxidant vitamins plus n-3 PUFAs for cardioprotection in clinical settings, such as post-operative atrial fibrillation, percutaneous coronary intervention following acute myocardial infarction and other events that are associated with ischaemia/reperfusion.

Pathophysiology and treatment of edema following femoropopliteal bypass surgery

Substantial lower-limb edema affects the majority of patients who undergo peripheral bypass surgery. Edema has impairing effects on the microvascular and the macrovascular circulation, causes discomfort and might delay the rehabilitation process of the patient. However, the pathophysiology of this edema is not well understood. The Cochrane Library and Medline were used to retrieve literature on edema following peripheral bypass surgery. Factors other than local wound healing alone are suggested in the literature to play a role, given the severity and duration of this edema. Hyperemia, microvascular permeability, reperfusion-associated inflammation and lymphatic disruptions are likely to facilitate the development of edema. Preventive methods could be lymphatic-sparing surgery, intraoperative antioxidative therapy and postoperative elevation. Successful treatment strategies to reduce postoperative edema are based on lymph massage and external compression. In conclusion, the pathophysiology of edema following peripheral surgery is not fully understood, although reperfusion-associated inflammation and lymphatic disruptions are likely to play a crucial role. When future less-invasive techniques prove to be successful, postoperative edema might be minimized. Until then, a careful lymphatic-sparing dissection should be executed when performing a peripheral bypass reconstruction. Postoperatively, the use of compression stockings and leg elevation are currently the golden standards.

Prevention of postoperative atrial fibrillation: novel and safe strategy based on the modulation of the antioxidant system

Postoperative atrial fibrillation (AF) is the most common arrhythmia following cardiac surgery with extracorporeal circulation. The pathogenesis of postoperative AF is multifactorial. Oxidative stress, caused by the unavoidable ischemia-reperfusion event occurring in this setting, is a major contributory factor. Reactive oxygen species (ROS)-derived effects could result in lipid peroxidation, protein carbonylation, or DNA oxidation of cardiac tissue, thus leading to functional and structural myocardial remodeling. The vulnerability of myocardial tissue to the oxidative challenge is also dependent on the activity of the antioxidant system. High ROS levels, overwhelming this system, should result in deleterious cellular effects, such as the induction of necrosis, apoptosis, or autophagy. Nevertheless, tissue exposure to low to moderate ROS levels could trigger a survival response with a trend to reinforce the antioxidant defense system. Administration of n-3 polyunsaturated fatty acids (PUFA), known to involve a moderate ROS production, is consistent with a diminished vulnerability to the development of postoperative AF. Accordingly, supplementation of n-3 PUFA successfully reduced the incidence of postoperative AF after coronary bypass grafting. This response is due to an up-regulation of antioxidant enzymes, as shown in experimental models. In turn, non-enzymatic antioxidant reinforcement through vitamin C administration prior to cardiac surgery has also reduced the postoperative AF incidence. Therefore, it should be expected that a mixed therapy result in an improvement of the cardioprotective effect by modulating both components of the antioxidant system. We present novel available evidence supporting the hypothesis of an effective prevention of postoperative AF including a two-step therapeutic strategy: n-3 PUFA followed by vitamin C supplementation to patients scheduled for cardiac surgery with extracorporeal circulation. The present study should encourage the design of clinical trials aimed to test the efficacy of this strategy to offer new therapeutic opportunities to patients challenged by ischemia-reperfusion events not solely in heart, but also in other organs such as kidney or liver in transplantation surgeries.

Local and systemic treatments for acute edema after burn injury: a systematic review of the literature

Burn injury is a complex trauma that results in local and generalized edema. Edema fluid limits the exchange of vital nutrients in healing the burn wound and will compromise vulnerable tissues. Although the importance of edema control in tissue salvage is recognized, treatments targeted at edema control have not been critically reviewed. Thus, the objective was to assess the evidence for the effectiveness of local and systemic treatments for edema management immediately after burn injury. Searches for randomized controlled trials were conducted of online databases, research and thesis registers, and grey literature repositories. Handsearches included journals, bibliographies, and proceedings. Authors were contacted to clarify and submit extra study details. Eight studies were included. Management of acute major burn resuscitation including colloid increases lung edema (mean difference [MD], 0.04 ml/ml alv vol; 95% confidence interval [CI], 0.03-0.04; P < .00001) and mortality (risk ratio, 3.67; 95% CI, 1.16-11.58; P = .03). Continuous administration of vitamin C in acute burn resuscitation reduces local wound edema (MD, -3.50 ml/g; 95% CI, -4.63 to -2.37; P < .00001) and systemic fluid retention (MD, -8.60 kg; 95% CI, -13.47 to -3.73; P = .0005). Local acute hand burn edema is reduced (MD, -29.00 ml; 95% CI, -53.14 to -4.86; P = .02), and active hand motion increased (MD, 10.00°; 95% CI, 4.58-15.42; P = .0003), using electrical stimulation with usual physiotherapy. Each review outcome was based on a small single-facility study. Thus, future research in intervention for acute burn edema must focus on multicentre trials and validation of outcome measures in the burn population.

Prospective randomized controlled trial to analyze the effects of intermittent pneumatic compression on edema following autologous femoropopliteal bypass surgery

Background

Patients who undergo autologous femoropopliteal bypass surgery develop postoperative edema in the revascularized leg. The effects of intermittent pneumatic compression (IPC) to treat and to prevent postreconstructive edema were examined in this study.

Methods

In a prospective randomized trial, patients were assigned to one of two groups. All patients suffered from peripheral arterial disease, and all were subjected to autologous femoropopliteal bypass reconstruction. Patients in group 1 used a compression stocking (CS) above the knee exerting 18 mmHg (class I) on the leg postoperatively for 1 week (day and night). Patients in group 2 used IPC on the foot postoperatively at night for 1 week. The lower leg circumference was measured preoperatively and at five postoperative time points. A multivariate analysis was done using a mixed model analysis of variance.

Results

A total of 57 patients were analyzed (CS 28; IPC 29). Indications for operation were severe claudication (CS 13; IPC 13), rest pain (10/5), or tissue loss (7/11). Revascularization was performed with either a supragenicular (CS 13; IPC10) or an infragenicular (CS 15; IPC 19) autologous bypass. Leg circumference increased on day 1 (CS/IPC): 0.4%/2.7%, day 4 (2.1%/6.1%), day 7 (2.5%/7.9%), day 14 (4.7%/7.3%), and day 90 (1.0%/3.3%) from baseline (preoperative situation). On days 1, 4, and 7 there was a significant difference in leg circumference between the two treatment groups.

Conclusions

Edema following femoropopliteal bypass surgery occurs in all patients. For the prevention and treatment of that edema the use of a class I CS proved superior to treatment with IPC. The use of CS remains the recommended practice following femoropopliteal bypass surgery.

Pharmacological interventions versus no pharmacological intervention for ischaemia reperfusion injury in liver resection surgery performed under vascular control

BACKGROUND

Vascular occlusion to reduce blood loss is used during elective liver resection but results in significant ischaemia reperfusion injury. This, in turn, might lead to significant postoperative liver dysfunction and morbidity. Various pharmacological drugs have been used with an intention to ameliorate the ischaemia reperfusion injury in liver resections.

OBJECTIVES

To assess the benefits and harms of different pharmacological agents versus no pharmacological interventions to decrease ischaemia reperfusion injury during liver resections where vascular occlusion was performed during the surgery.

SEARCH STRATEGY

We searched The Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE, and Science Citation Index Expanded until January 2009.

SELECTION CRITERIA

We included randomised clinical trials, irrespective of language or publication status, comparing any pharmacological agent versus placebo or no pharmacological agent during elective liver resections with vascular occlusion.

DATA COLLECTION AND ANALYSIS

Two authors independently identified trials for inclusion and independently extracted the data. We analysed the data with both the fixed-effect and the random-effects models using RevMan Analysis. We calculated the risk ratio (RR) or mean difference (MD) with 95% confidence intervals (CI) based on intention-to-treat analysis or available case analysis.

MAIN RESULTS

We identified a total of 15 randomised trials evaluating 11 different pharmacological interventions (methylprednisolone, multivitamin antioxidant infusion, vitamin E infusion, amrinone, prostaglandin E1, pentoxifylline, mannitol, trimetazidine, dextrose, allopurinol, and OKY 046 (a thromboxane A2 synthetase inhibitor)). All trials had high risk of bias. There were no significant differences between the groups in mortality, liver failure, or perioperative morbidity. The trimetazidine group had a significantly shorter hospital stay than control (MD -3.00 days; 95% CI -3.57 to -2.43). There were no significant differences in any of the clinically relevant outcomes in the remaining comparisons. Methylprednisolone improved the enzyme markers of liver function and trimetazidine, methylprednisolone, and dextrose reduced the enzyme markers of liver injury compared with controls. However, there is a high risk of type I and type II errors because of the few trials included, the small sample size in each trial, and the risk of bias.

AUTHORS' CONCLUSIONS

Trimetazidine, methylprednisolone, and dextrose may protect against ischaemia reperfusion injury in elective liver resections performed under vascular occlusion, but this is shown in trials with small sample sizes and high risk of bias. The use of these drugs should be restricted to well-designed randomised clinical trials before implementing them in clinical practice.

Pilot study on the effect of parenteral vitamin E on ischemia and reperfusion induced liver injury: a double blind, randomized, placebo-controlled trial

BACKGROUND AND AIMS

Liver surgery usually involves ischemia and reperfusion (I/R) which results in oxidative stress and cell damage. The administration of antioxidants should diminish or prevent this damage. The purpose of this study was to investigate the effect of the antioxidant vitamin E on I/R injury.

METHODS

We carried out a placebo-controlled double-blind study on 68 patients undergoing elective, tumor-related, partial liver resection. 47 patients were qualified for the per protocol population based evaluation. The patients were randomly assigned to two groups. The day before surgery one group received three infusions containing vitamin E (600 IU=540 mg vitamin E emulsion). The other group received three infusions of placebo.

RESULTS

Length of stay in the intensive care unit (ICU) was significantly shorter in the verum group than in the placebo group (P<0.05). There were signs of improvement for AUC AST (P<0.05), ALT and GLDH in the verum group after surgery. Serum vitamin E concentration increased after administration of vitamin E infusion and declined in both treatment groups after surgery (P<0.01). In the verum group vitamin E deficiency was prevented while vitamin E concentration remained low in the placebo group (P<0.01).

CONCLUSIONS

The findings from this study indicate that preoperative administration of vitamin E is safe and that this treatment may have beneficial effects by reducing the impact of I/R injury in liver surgery.

Multivitamin administration before ischemia reduces ischemia-reperfusion injury in rabbit skeletal muscle

This study investigated the effect of a multivitamin preparation administered before ischemia or before reperfusion, on ischemia-reperfusion (I/R) injury of skeletal muscle. An in vivo hindlimb skeletal muscle I/R model (2.5 h/2 h) was carried out on adult New Zealand white rabbits. Animals used as I/R models were treated with a multivitamin preparation (0.4 ml/kg bw i.v. bolus), containing alpha-tocopherol, ascorbic acid, retinol, vitamin B complex, 30 min before starting ischemia (group MV(isc)) or 5 min before reperfusion (group MV(rep)) and compared to animals with I/R without treatment (group IR) and sham operated animals (group SHAM). Interstitial edema (muscle interfiber area, %MIFA) and changes in microvessel size (microvessel cross sectional area, MVCSA, microm(2)) were measured. Plasma malondialdehyde concentrations (MDA-TBA, nmol/ml) served as a measure of lipid peroxidation. After 2h of reperfusion, ischemia-reperfusion developed a significant microvascular constriction and an interstitial edema (IR, vs SHAM;P<< 0.01), but administration of antioxidative vitamins before the onset of ischemia reduced microvascular constriction and edema formation (P<< 0.05 vs IR group). In a similar manner, administration of vitamins before ischemia lowered plasma MDA-TBA levels as compared to the untreated group during reperfusion (p<< 0. 05). In animals treated with vitamins before reperfusion, the biochemical and morphological results showed no differences as compared to the untreated group. Antioxidative treatment with a multivitamin preparation exerted a beneficial effect on I/R injury of skeletal muscle when the aforementioned vitamins were administered before ischemia but not before the onset of reperfusion.

Normothermic liver ischemia and antioxidant treatment during hepatic resections

The purpose of our study was to evaluate the clinical impact of reperfusion injury after normothermic ischemia during major liver resections and the effect of an intraoperative antioxidant infusion. This prospective randomized study comprised 50 patients; half of them (treatment group) were given an antioxidant infusion containing tocopherol and ascorbate immediately prior to reperfusion onset. Venous blood samples for the determination of MDA-TBARS (malondialdehyde-thiobarbituric acid reactive substances) by a HPLC-based test as a marker of lipid peroxidation were taken prior to ischemia, 30 min after reperfusion onset and at the end of the operation. In the control group there was a significant increase of MDA-TBARS (p = 0.001) at 30 min after reperfusion onset. At the end of the operation the values had returned to the initial level. The treatment group showed only a marginal increase (p-value for the difference between the two groups: 0.007). After exclusion of the patients with histologically proven advanced cirrhosis the increase in the control group (p < 0.001) and the difference between the increase in the two groups (p = 0.001) became more significant. Prothrombin time was also significantly better in the treatment group (p = 0.003). Postoperative complications such as prolonged liver failure, bleeding disorders and infections were seen more often in the control group. In our study MDA-TBARS was increased after liver ischemia, but in patients with advanced cirrhosis the effect was smaller or even absent. This increase and possible clinical consequences of reperfusion injury could be reduced by intraoperative administration of an antioxidant infusion.

Determination of ascorbic acid in plasma and urine by high performance liquid chromatography with ultraviolet detection

A reliable simple reversed-phase liquid chromatographic method for the routine determination of ascorbic acid in plasma and urine with ultraviolet detection is described. This method enables the complete separation of the ascorbic acid peak from others with a recovery of above 95% within 8 minutes. The method can be used for analysing multiple samples within a day. In addition, the storage conditions and stability of ascorbic acid in plasma and urine were investigated. Samples of plasma and urine can be stored on ice in darkness for at least 60 min without reduction of ascorbic acid concentration. Prepared samples can be stored in darkness at 4 degrees C for at least 120 min and in liquid nitrogen for 42 days.

Lower limb oedema following distal arterial bypass grafting

Lower-limb oedema following arterial bypass surgery for ischemia is a common sequela which can complicate wound healing or delay resumption of mobility. Its exact pathogenesis remains uncertain but many theories have been proposed. Lymphatic disruption during arterial exposure, and endothelial damage from atrophy of the media and oxygen-derived free radical release are currently favoured hypotheses. Infrequently, deep vein thrombosis follows surgery and may exacerbate the condition. Efforts aimed at reducing the oedema, such as the use of lymphatic preserving incisional approaches or the use of antioxidants, have given conflicting results. The use of compression hosiery and leg elevation appear to be the most effective measures in reducing postoperative lower limb oedema.

Short-term parenteral application of alpha-tocopherol leads to increased concentration in plasma and tissues of the rat

Numerous studies suggest that supplemental vitamin E prior to or during vast surgeries might diminish or even prevent ischemia/reperfusion-induced injuries. In the present placebo-controlled study male Sprague-Dawley rats were supplemented parenterally or orally with alpha-tocopherol for three consecutive days. The applied amount of alpha-tocopherol was 2.3 micromol per day for oral and 1.2 micromol per day for parenteral supplementation. The enrichment of vitamin E concentrations in plasma and tissue samples (aortic endothelium, liver, and lung) was determined by HPLC. The vitamin E level was elevated following intravenous supplementation in plasma (21.4 +/- 1.9 micromol/L vs. 10.2 +/- 1.7 micromol/L in parenteral control group), in aortic endothelium (1.1 +/- 0.2 pmol/mm2 vs. 0.5 +/- 0.1 pmol/mm2) and in liver and lung (41.3 +/- 7.5 pmol/mg vs. 22.9 +/- 6.5 pmol/mg and 75.6 +/- 13.6 pmol/mg vs. 51.7 +/- 5.9 pmol/mg, respectively). Oral supplementation for three days also led to an increased level in liver (38.2 +/- 7.7 pmol/mg vs. 22.9 +/- 6.6 pmol/mg in oral control group) and in lung (67.8 +/- 5.7 pmol/mg vs. 51.7 +/- 9.3 pmol/mg) but not in aortic endothelium or plasma (0.8 +/- 0.3 pmol/mm2 vs. 0.6 +/- 0.3 pmol/mm2 and 12.0 +/- 2.2 micromol/L vs. 10.7 +/- 2.6 micromol/L).

The impact of antioxidant and splanchnic-directed therapy on persistent uncorrected gastric mucosal pH in the critically injured trauma patient

BACKGROUND

Critically ill trauma patients with gastric intramucosal acidosis, as measured by gastric tonometry, have an increased incidence of multiple organ dysfunction syndrome despite supranormal O2 delivery. We altered our resuscitation protocol to maximize splanchnic blood flow and decrease oxygen-derived free radical damage.

DESIGN

Prospective clinical trial with historical controls.

METHODS

The protocol differed from control by including administration of folate, mannitol, and low-dose isoproterenol. All patients had gastric tonometers and pulmonary artery catheters. If the intramucosal pH (pHi) was less than 7.25, splanchnic-sparing inotropic and vasodilatory agents were used to optimize systemic cardiac output. Two groups of trauma patients with persistent intramucosal acidosis at 24 hours (pHi < 7.25) were compared: a control group (n = 7), and patients who received the splanchnic/antioxidant protocol (n = 13).

RESULTS

The two groups were similar based on Acute Physiology and Chronic Health Evaluation II score, Injury Severity Score, age, cardiac index, oxygen delivery, and oxygen consumption. The "splanchnic therapy" group had fewer organ system failures as well as shortened length of intensive care unit and hospital stay. Three of 7 patients in the control group and 2 of 13 patients in the splanchnic therapy group had a final pHi < 7.25.

CONCLUSION

Gastric tonometry-guided resuscitation and antioxidant/splanchnic therapy in critically ill trauma patients with persistent gastric mucosal acidosis may decrease multiple organ dysfunction syndrome.