Wound tissue oxygen tension predicts the risk of wound infection in surgical patients

[Water-filtered infrared-A (wIRA) promotes wound healing]

Water-filtered infrared-A (wIRA) is a special form of heat radiation with high tissue penetration and low thermal load to the skin surface which promotes the healing of acute and chronic wounds both by thermal and thermic as well as by non-thermal and non-thermic effects. Water-filtered infrared-A increases tissue temperature (+ 2.7 °C at a tissue depth of 2 cm), tissue oxygen partial pressure (+ 32 % at a tissue depth of 2 cm) and tissue perfusion. These three factors are decisive for a sufficient supply of tissue with energy and oxygen and consequently also for wound healing and infection defense. Water-filtered infrared-A promotes normal as well as disturbed wound healing by diminishing inflammation and exudation, by promotion of infection defense and regeneration, and by alleviation of pain. These effects have been proven in a total of seven prospective studies (of these six randomized controlled studies) with most of the effects having an evidence level of Ia or Ib. The additional cases of complicated courses of wound healing presented in this article illustrate the proven effects of wIRA. Not only in the 6 presented cases wIRA turned the complicated courses of wound healing for the better and facilitated the healing of the wounds after varying total times of irradiation (in the 6 cases 51-550 h) and after variable times of wound care and mostly after transplantation of split skin grafts. In complicated courses of wound healing wIRA does not replace consultation and, when indicated, treatment by an experienced plastic surgeon and by a surgeon specialized in septic surgery. With these limitations wIRA can be recommended as a valuable complement for the treatment of acute as well as of chronic wounds.

The Effects of Local Warming on Surgical Site Infection

BACKGROUND

Surgical site infections (SSI) account for a major proportion of hospital-acquired infections. They are associated with longer hospital stay, readmissions, increased costs, mortality, and morbidity. Reducing SSI is a goal of the Surgical Care Improvement Project and identifying interventions that reduce SSI effectively is of interest. In a single-blinded randomized controlled trial (RCT) we evaluated the effect of localized warming applied to surgical incisions on SSI development and selected cellular (immune, endothelial) and tissue responses (oxygenation, collagen).

METHODS

After Institutional Review Board approval and consent, patients having open bariatric, colon, or gynecologic-oncologic related operations were enrolled and randomly assigned to local incision warming (6 post-operative treatments) or non-warming. A prototype surgical bandage was used for all patients. The study protocol included intra-operative warming to maintain core temperature ≥36°C and administration of 0.80 FIO2. Patients were followed for 6 wks for the primary outcome of SSI determined by U.S. Centers for Disease Control (CDC) criteria and ASEPSIS scores (additional treatment; presence of serous discharge, erythema, purulent exudate, and separation of the deep tissues; isolation of bacteria; and duration of inpatient stay). Tissue oxygen (PscO2) and samples for cellular analyses were obtained using subcutaneous polytetrafluoroethylene (ePTFE) tubes and oxygen micro-electrodes implanted adjacent to the incision. Cellular and tissue ePTFE samples were evaluated using flow cytometry, immunohistochemistry, and Sircol™ collagen assay (Biocolor Ltd., Carrickfergus, United Kingdom).

RESULTS

One hundred forty-six patients participated (n=73 per group). Study groups were similar on demographic parameters and for intra-operative management factors. The CDC defined rate of SSI was 18%; occurrence of SSI between groups did not differ (p=0.27). At 2 wks, warmed patients had better ASEPSIS scores (p=0.04) but this difference was not observed at 6 wks. There were no significant differences in immune, endothelial cell, or collagen responses between groups. On post-operative days one to two, warmed patients had greater PscO2 change scores with an average PscO2 increase of 9-10 mm Hg above baseline (p<0.04).

CONCLUSIONS

Post-operative local warming compared with non-warming followed in this study, which included intra-operative warming to maintain normothermia and FIO2 level of 0.80, did not reduce SSI and had no effect on immune, endothelial cell presence, or collagen synthesis. PscO2 increased significantly with warming, however, the increase was modest and less than expected or what has been observed in studies testing other interventions.

The effects of high perioperative inspiratory oxygen fraction for adult surgical patients

BACKGROUND

Available evidence on the effects of a high fraction of inspired oxygen (FIO2) of 60% to 90% compared with a routine fraction of inspired oxygen of 30% to 40%, during anaesthesia and surgery, on mortality and surgical site infection has been inconclusive. Previous trials and meta-analyses have led to different conclusions on whether a high fraction of supplemental inspired oxygen during anaesthesia may decrease or increase mortality and surgical site infections in surgical patients.

OBJECTIVES

To assess the benefits and harms of an FIO2 equal to or greater than 60% compared with a control FIO2 at or below 40% in the perioperative setting in terms of mortality, surgical site infection, respiratory insufficiency, serious adverse events and length of stay during the index admission for adult surgical patients.We looked at various outcomes, conducted subgroup and sensitivity analyses, examined the role of bias and applied trial sequential analysis (TSA) to examine the level of evidence supporting or refuting a high FIO2 during surgery, anaesthesia and recovery.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, BIOSIS, International Web of Science, the Latin American and Caribbean Health Science Information Database (LILACS), advanced Google and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) up to February 2014. We checked the references of included trials and reviews for unidentified relevant trials and reran the searches in March 2015. We will consider two studies of interest when we update the review.

SELECTION CRITERIA

We included randomized clinical trials that compared a high fraction of inspired oxygen with a routine fraction of inspired oxygen during anaesthesia, surgery and recovery in individuals 18 years of age or older.

DATA COLLECTION AND ANALYSIS

Two review authors extracted data independently. We conducted random-effects and fixed-effect meta-analyses, and for dichotomous outcomes, we calculated risk ratios (RRs). We used published data and data obtained by contacting trial authors.To minimize the risk of systematic error, we assessed the risk of bias of the included trials. To reduce the risk of random errors caused by sparse data and repetitive updating of cumulative meta-analyses, we applied trial sequential analyses. We used Grades of Recommendation, Assessment, Development and Evaluation (GRADE) to assess the quality of the evidence.

MAIN RESULTS

We included 28 randomized clinical trials (9330 participants); in the 21 trials reporting relevant outcomes for this review, 7597 participants were randomly assigned to a high fraction of inspired oxygen versus a routine fraction of inspired oxygen.In trials with an overall low risk of bias, a high fraction of inspired oxygen compared with a routine fraction of inspired oxygen was not associated with all-cause mortality (random-effects model: RR 1.12, 95% confidence interval (CI) 0.93 to 1.36; GRADE: low quality) within the longest follow-up and within 30 days of follow-up (Peto odds ratio (OR) 0.99, 95% CI 0.61 to 1.60; GRADE: low quality). In a trial sequential analysis, the required information size was not reached and the analysis could not refute a 20% increase in mortality. Similarly, when all trials were included, a high fraction of inspired oxygen was not associated with all-cause mortality to the longest follow-up (RR 1.07, 95% CI 0.87 to 1.33) or within 30 days of follow-up (Peto OR 0.83, 95% CI 0.54 to 1.29), both of very low quality according to GRADE. Neither was a high fraction of inspired oxygen associated with the risk of surgical site infection in trials with low risk of bias (RR 0.86, 95% CI 0.63 to 1.17; GRADE: low quality) or in all trials (RR 0.87, 95% CI 0.71 to 1.07; GRADE: low quality). A high fraction of inspired oxygen was not associated with respiratory insufficiency (RR 1.25, 95% CI 0.79 to 1.99), serious adverse events (RR 0.96, 95% CI 0.65 to 1.43) or length of stay (mean difference -0.06 days, 95% CI -0.44 to 0.32 days).In subgroup analyses of nine trials using preoperative antibiotics, a high fraction of inspired oxygen was associated with a decrease in surgical site infections (RR 0.76, 95% CI 0.60 to 0.97; GRADE: very low quality); a similar effect was noted in the five trials adequately blinded for the outcome assessment (RR 0.79, 95% CI 0.66 to 0.96; GRADE: very low quality). We did not observe an effect of a high fraction of inspired oxygen on surgical site infections in any other subgroup analyses.

AUTHORS' CONCLUSIONS

As the risk of adverse events, including mortality, may be increased by a fraction of inspired oxygen of 60% or higher, and as robust evidence is lacking for a beneficial effect of a fraction of inspired oxygen of 60% or higher on surgical site infection, our overall results suggest that evidence is insufficient to support the routine use of a high fraction of inspired oxygen during anaesthesia and surgery. Given the risk of attrition and outcome reporting bias, as well as other weaknesses in the available evidence, further randomized clinical trials with low risk of bias in all bias domains, including a large sample size and long-term follow-up, are warranted.

Continuous wound infusion of ropivacaine for the control of pain after thoracolumbar spinal surgery: a randomized clinical trial

PURPOSE

A prospective randomized clinical trial was carried out to observe the analgesic efficacy of ropivacaine for postoperative pain following thoracolumbar spinal surgery.

METHODS

Seventy-one patients with elective posterior thoracolumbar spinal surgery were randomly divided into two groups. Local group received 0.33 % ropivacaine by pump through the wound, and intravenous group received flurbiprofen axetil, pentazocine and palonosetron via intravenous pump. We evaluated the level of pain, the incidence of adverse reactions at 2, 4, 6, 12, 24, 36 and 48 h after operation, and the occurrence of chronic pain 3 months later.

RESULTS

There were no significant differences in the pain level between the two groups. However, the incidence of nausea, vomiting and chronic pain was significantly lower in the local group.

CONCLUSIONS

Our results showed that local infusion of ropivacaine achieved similar analgesic effects to intravenous delivery of analgesic drugs, but significantly reduced incidence of nausea, vomiting and chronic pain.

Intra-operative tissue oxygen tension is increased by local insufflation of humidified-warm CO2 during open abdominal surgery in a rat model

INTRODUCTION

Maintenance of high tissue oxygenation (PtO2) is recommended during surgery because PtO2 is highly predictive of surgical site infection and colonic anastomotic leakage. However, surgical site perfusion is often sub-optimal, creating an obstructive hurdle for traditional, systemically applied therapies to maintain or increase surgical site PtO2. This research tested the hypothesis that insufflation of humidified-warm CO2 into the abdominal cavity would increase sub-peritoneal PtO2 during open abdominal surgery.

MATERIALS AND METHODS

15 Wistar rats underwent laparotomy under general anesthesia. Three sets of randomized cross-over experiments were conducted in which the abdominal cavity was subjected to alternating exposure to 1) humidified-warm CO2 & ambient air; 2) humidified-warm CO2 & dry-cold CO2; and 3) dry-cold CO2 & ambient air. Sub-peritoneal PtO2 and tissue temperature were measured with a polarographic oxygen probe.

RESULTS

Upon insufflation of humidified-warm CO2, PtO2 increased by 29.8 mmHg (SD 13.3; p<0.001), or 96.6% (SD 51.9), and tissue temperature by 3.0°C (SD 1.7 p<0.001), in comparison with exposure to ambient air. Smaller, but significant, increases in PtO2 were seen in experiments 2 and 3. Tissue temperature decreased upon exposure to dry-cold CO2 compared with ambient air (-1.4°C, SD 0.5, p = 0.001).

CONCLUSIONS

In a rat model, insufflation of humidified-warm CO2 into the abdominal cavity during open abdominal surgery causes an immediate and potentially clinically significant increase in PtO2. The effect is an additive result of the delivery of CO2 and avoidance of evaporative cooling via the delivery of the CO2 gas humidified at body temperature.

Smoking as an independent predictor of reoperation after lumbar laminectomy: a study of 500 cases

OBJECT

This study aimed to identify the factors predicting an increased risk for reoperation in patients who had undergone a lumbar laminectomy.

METHODS

The authors retrospectively reviewed the electronic medical records of all patients who had undergone firsttime, bilateral laminectomy at 1, 2, or 3 levels for lumbar spondylosis at the authors' institution. Patients who underwent fusion, laminotomy, discectomy, or complete facetectomy were excluded. The patients' preoperative symptoms and comorbidities were also obtained from their medical records.

RESULTS

Over an average follow-up period of 46.8 months, of 500 patients who had undergone laminectomy at 1, 2, or 3 levels, 81 patients (16.2%) developed subsequent spinal disorders that required a reoperation. A multiple logistic regression analysis identified smoking as an independent predictor of reoperation (OR 2.15, p = 0.01). Smoking was also an independent predictor of reoperation after a single-level laminectomy (OR 11.3, p = 0.02) and after a multilevel (that is, involving 2 or 3 levels) laminectomy (OR 1.98, p = 0.05). For 72 patients undergoing reoperation only for spinal degeneration, smoking remained an independent, statistically significant predictor of reoperation (OR 2.06, p = 0.04). Nine patients underwent reoperation for nondegenerative conditions (hematoma, wound infection, or wound dehiscence), and in these patients, chronic obstructive pulmonary disease was the only statistically significant predictor of reoperation (OR 8.92, p = 0.03).

CONCLUSIONS

Smoking was the strongest predictor of reoperation in patients who had undergone single-level laminectomy, multilevel laminectomy, or reoperation for progression of spinal degeneration. These findings suggest that smokers have worse outcomes of lumbar decompression than nonsmokers.

Photoacoustic lifetime imaging for direct in vivo tissue oxygen monitoring

Measuring the partial pressure of oxygen (pO₂) in tissue may provide physicians with essential information about the physiological state of tissue. However, currently available methods for measuring or imaging tissue pO₂ have significant limitations, preventing them from being widely used in clinics. Recently, we have reported a direct and noninvasive in vivo imaging modality based on the photoacoustic lifetime which overcomes certain drawbacks of the existing methods. The technique maps the excited triplet state of oxygen-sensitive dye, thus reflecting the spatial and temporal distributions of tissue oxygen. Here, we present two studies which apply photoacoustic lifetime imaging (PALI) to monitor changes of tissue oxygen induced by external modulations. The first study modulates tissue oxygen by controlling the percentage of oxygen a normal mouse inhales. We demonstrate that PALI is able to reflect the change in oxygen level with respect to normal, oxygen-rich, and oxygen-poor breathing conditions. The second study involves an acute ischemia model using a thin thread tied around the hindlimb of a normal mouse to reduce the blood flow. PALI images were acquired before, during, and after the restriction. The drop of tissue pO₂ and recovery from hypoxia due to reperfusion were tracked and observed by PALI.

Surgical site infections (SSIs) after stoma reversal (SR): risk factors, implications, and protective strategies

BACKGROUND

Stoma reversals (SRs) are commonly performed with potentially significant postoperative complications including surgical site infections (SSIs). Our aim was to determine the incidence and risk factors for SSIs in a large cohort of SR patients.

DESIGN

We reviewed our institutional 2006-2011 American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database for 30-day SSIs in patients undergoing SR. Records were additionally reviewed for 10 non-ACS-NSQIP variables. The primary outcome was SSI after SR. Secondary outcomes were additional 30-day postoperative complications and length-of-stay. Predictors of SSIs were identified using multivariable logistic regression.

RESULTS

From 528 SR patients, 36 patients developed a SSI (6.8 %). Most patients underwent SR for loop ileostomies (76.5 %) after index operations for ulcerative colitis (38.6 %) and colorectal cancer (27.8 %). SSI patients had fewer subcutaneous drains compared to patients with no SSI and had significantly higher rates of smoking, ASA 3-4 classification and laparotomies at SR (p < 0.05). Patients with SSI had increased length-of-stay and 30-day morbidities including sepsis and returns to the operating room (p < 0.05) compared to no-SSI patients. On multivariable analysis, subcutaneous drain placement was suggestive of SSI protection (odds ratio [OR] 0.52, 95 % confidence interval [CI] 0.2-1.1), but only smoking was significantly associated with an increased risk for SSI (OR 2.4, 95 % CI 1.1-5.4).

CONCLUSIONS

Smoking increased the risk of SR SSIs in patients by over twofold, and SR SSIs are associated with additional significant morbidities. Smoking cessation should be an important part of any SSI risk-reduction strategy.

Dynamic oxygenation measurements using a phosphorescent coating within a mammary window chamber mouse model

Phosphorescent lifetime imaging was employed to measure the spatial and temporal distribution of oxygen partial pressure in tissue under the coverslip of a mammary window chamber breast cancer mouse model. A thin platinum-porphyrin coating, whose phosphorescent lifetime varies monotonically with oxygen partial pressure, was applied to the coverslip surface. Dynamic temporal responses to induced modulations in oxygenation levels were measured using this approach.

Efficacy of postoperative continuous wound infiltration with local anesthesia after open hepatectomy

Objectives:

Local anesthetic wound infiltration is widely used as an effective adjunct during multimodal postoperative pain management. The aim of this study was to evaluate the effectiveness of continuous wound infusion of ropivacaine in postoperative pain relief, opioid sparing, incidence of nausea and vomiting, and bowel and liver function improvement in patients undergoing open hepatectomy.

Methods:

Forty patients undergoing open hepatectomy were enrolled in this prospective, randomized, double-blinded, placebo-controlled trial. Patients were divided into 2 groups: the 0.9% saline continuous infusion group (the control group; n=20) and the ropivacaine continuous infusion group (the Ropi group; n=20). Outcomes measured postoperatively were pain score at rest and on movement, sufentanil consumption, incidence of nausea and vomiting, and sedation score across 48 postoperative hours. Time to bowel recovery, liver function change, mean length of hospitalization, patient satisfaction, and other data after 48 postoperative hours were collected until hospital discharge.

Results:

Pain scores at rest were lower for the ropivacaine group and reached significance after 8 and 16 hours (P<0.01). Sufentanil consumption (41.50±21.80 vs. 89.70±35.22 μg; P<0.01) after 48 hours, time to bowel recovery (1.80±0.70 vs. 3.15±1.04 d; P<0.01), incidence of nausea and vomiting (1.75±0.72 vs. 2.40±0.68; P<0.05), and mean length of hospitalization (5.6±2.44 vs. 7.35±2.85 d; P<0.01) were significantly reduced, and the sedation score and liver function change were also comparable between the 2 groups. There was no difference with respect to pain scores on movement, nor with respect to patient satisfaction.

Conclusions:

Surgical wound infusion with ropivacaine after hepatectomy can improve pain relief at rest and accelerate recovery and discharge.

Risk Factors Associated With Surgical Site Infection After Pediatric Posterior Spinal Fusion Procedure

Objective.

To identify risk factors associated with surgical site infection (SSI) after pediatric posterior spinal fusion procedure by examining characteristics related to the patient, the surgical procedure, and tissue hypoxia.

Design.

Retrospective case-control study nested in a hospital cohort study.

Setting.

A 475-bed, tertiary care children's hospital.

Methods.

All patients who underwent a spinal fusion procedure during the period from January 1995 through December 2006 were included. SSI cases were identified by means of prospective surveillance using National Nosocomial Infection Surveillance system definitions. Forty-four case patients who underwent a posterior spinal fusion procedure and developed an SSI were identified and evaluated. Each case patient was matched (on the basis of date of surgery, ± 3 months) to 3 control patients who underwent a posterior spinal fusion procedure but did not develop an SSI. Risk factors for SSI were evaluated by univariate analysis and multivariable conditional logistic regression. Odds ratios (ORs), with 95% confidence intervals (CIs) andPvalues, were calculated.

Results.

From 1995 to 2006, the mean annual rate of SSI after posterior spinal fusion procedure was 4.4% (range, 1.1%—6.7%). Significant risk factors associated with SSI in the univariate analysis included the following: a body mass index (BMI) greater than the 95th percentile (OR, 3.5 [95% CI, 1.5–8.3]); antibiotic prophylaxis with clindamycin, compared with other antibiotics (OR, 3.5 [95% CI, 1.2 10.0]); inappropriately low dose of antibiotic (OR, 2.6 [95% CI, 1.0–6.6]); and a longer duration of hypothermia (ie, a core body temperature of less than 35.5°C) during surgery (OR, 0.4 [95% CI, 0.2–0.9]). An American Society of Anesthesiologists (ASA) score of greater than 2, obesity (ie, a BMI greater than the 95th percentile), antibiotic prophylaxis with clindamycin, and hypothermia were statistically significant in the multivariable model.

Conclusion.

An ASA score greater than 2, obesity, and antibiotic prophylaxis with clindamycin were independent risk factors for SSI. Hypothermia during surgery appears to provide protection against SSI in this patient population.

Thermoregulation and Risk of Surgical Site Infection

Surgical site infections (SSIs) occur in approximately 2%–5% of patients undergoing surgery in the acute care setting in the United States. These infections result in increased length of stay, higher risk of death, and increased cost of care compared with that in uninfected surgical patients. Given the inclusion of maintenance of perioperative normothermia for all major surgeries as a means of lowering the risk of infection in the Surgical Care Improvement Project 2009, we prepared a summary of the literature to determine the strength and quantity of the evidence underlying the performance measure. Although the data are generally supportive of perioperative normothermia as a means of reducing the risk of SSIs, a more rigorous approach using standard SSI definitions as well as standardized temperature measurements (and timing thereof) will further delineate the role played by temperature regulation in SSI development.

A dissolved oxygen dressing: A pilot study in an ischemic skin flap model

Objectives

To determine if skin flap failure rates could be improved with the use of a dissolved oxygen wound dressing in a porcine model.

Methods

Full-thickness skin flaps (4 × 16 cm) were raised on pigs. Flaps were randomly assigned after surgery to experimental treatment with a dissolved oxygen dressing (treatment group) or a hydrogel dressing (control group). Flaps were evaluated daily for 14 days. Skin flaps that failed any one of four key clinical outcomes were considered failures. Histological parameters (including skin and subcutaneous necrosis, inflammation, ischemia, fibrosis, and bacterial load) were compared by a blinded histopathologist.

Results

Sixteen full-thickness skin flaps were raised on four pigs. All animals survived surgery and all incisions were evaluable. Clinical flap failure was observed in six (75%) control-treated wounds and in two (25%) dissolved oxygen-treated wounds. Histological evaluation demonstrated no significant differences in the proximal 75% of the flaps. There were significant differences in a number of histological parameters in the distal 25% in favor of the dissolved oxygen dressing.

Conclusions

Flaps treated with a dissolved oxygen dressing had fewer clinical failures and improved histological profiles compared with control-treated flaps, suggesting that increasing local oxygen supply may improve the local wound healing environment.

Effect of postoperative use of nasal oxygen catheter supplementation in wound healing following total knee arthroplasty

OBJECTIVES

Healing is an event that is fundamental to the success of total knee arthroplasty. The aims of the present study were to compare the rates of complications related to wound healing between two groups of volunteers submitted to total knee arthroplasty and to evaluate the effects of postoperative oxygen supplementation by means of a nasal catheter.

METHOD

A total of 109 patients who underwent total knee arthroplasty were randomized into two groups, namely, groups that did and did not receive postoperative oxygen supplementation via a nasal catheter. The surgical wound was monitored every day during the hospital stay and on the 7th, 14th, 21st, 30th and 42nd postoperative days. Characteristics related to healing were observed, including hyperemia, dehiscence, necrosis, phlyctenules and deep and superficial infection.

RESULTS

There were no cases of deep infection. Hyperemia was statistically correlated with the total number of complications in the groups, with oxygen demonstrated to be a protective factor against hyperemia. Approximately 30% of the patients who exhibited hyperemia had other complications, independent of oxygen supplementation.

CONCLUSION

Oxygen supplementation following total knee arthroplasty was shown to be effective in diminishing hyperemia around the operative wound. The development of hyperemia was a precursor to other complications, irrespective of whether oxygen supplementation was used.

Endogenous bone regeneration is dependent upon a dynamic oxygen event

Amputation of the digit tip within the terminal phalangeal bone of rodents, monkeys, and humans results in near-perfect regeneration of bone and surrounding tissues; however, amputations at a more proximal level fail to produce the same regenerative result. Digit regeneration is a coordinated, multifaceted process that incorporates signaling from bioactive growth factors both in the tissue matrix and from several different cell populations. To elucidate the mechanisms involved in bone regeneration we developed a novel multi-tissue slice-culture model that regenerates bone ex vivo via direct ossification. Our study provides an integrated multi-tissue system for bone and digit regeneration and allows us to circumvent experimental limitations that exist in vivo. We used this slice-culture model to evaluate the influence of oxygen on regenerating bone. Micro-computed tomography (µCT) and histological analysis revealed that the regenerative response of the digit is facilitated in part by a dynamic oxygen event, in which mutually exclusive high and low oxygen microenvironments exist and vacillate in a coordinated fashion during regeneration. Areas of increased oxygen are initially seen in the marrow and then surrounding areas of vasculature in the regenerating digit. Major hypoxic events are seen at 7 days postamputation (DPA 7) in the marrow and again at DPA 12 in the blastema, and manipulation of oxygen tensions during these hypoxic phases can shift the dynamics of digit regeneration. Oxygen increased to 21% oxygen tension can either accelerate or attenuate bone mineralization in a stage-specific manner in the regenerative timeline. These studies not only reveal a circumscribed frame of oxygen influence during bone regeneration, but also suggest that oxygen may be one of the primary signaling influences during regeneration.

Can hyperbaric oxygen be used to prevent deep infections in neuro-muscular scoliosis surgery?

BACKGROUND

The prevalence of postoperative wound infection in patients with neuromuscular scoliosis surgery is significantly higher than that in patients with other spinal surgery. Hyperbaric oxygen has been used as a supplement to treat postsurgical infections. Our aim was to determine beneficiary effects of hyperbaric oxygen treatment in terms of prevention of postoperative deep infection in this specific group of patients in a retrospective study.

METHODS

Forty two neuromuscular scoliosis cases, operated between 2006-2011 were retrospectively reviewed. Patients who had presence of scoliosis and/or kyphosis in addition to cerebral palsy or myelomeningocele, postoperative follow-up >1 year and posterior only surgery were the subjects of this study. Eighteen patients formed the Hyperbaric oxygen prophylaxis (P-HBO) group and 24, the control group. The P-HBO group received 30 sessions of HBO and standard antibiotic prophylaxis postoperative, and the control group (received standard antibiotic prophylaxis).

RESULTS

In the P-HBO group of 18 patients, the etiology was cerebral palsy in 13 and myelomeningocele in 5 cases with a mean age of 16.7 (11-27 yrs). The average follow-up was 20.4 months (12-36mo). The etiology of patients in the control group was cerebral palsy in 17, and myelomeningocele in 7 cases. The average age was 15.3 years (8-32 yrs). The average follow-up was 38.7 months (18-66mo). The overall incidence of infection in the whole study group was 11.9% (5/42). The infection rate in the P-HBO and the control group were 5.5% (1/18), and 16.6% (4/24) respectively. The use of HBO was found to significantly decrease the incidence of postoperative infections in neuromuscular scoliosis patients.

CONCLUSION

In this study we found that hyperbaric oxygen has a possibility to reduce the rate of post-surgical deep infections in complex spine deformity in high risk neuromuscular patients.

Does close temperature regulation affect surgical site infection rates?

The argument for close temperature control, to which regulatory bodies have held health systems in an effort to reduce the burden of hospital-acquired infections, is not fully supported by current evidence. The literature is complex on the topic, and overinterpretation of historical data supporting close temperature regulation does not preclude an important recognition of these early works' contribution to high-quality surgical care. Avoidance of hypothermia through the regular use of active rewarming should be a routine part of safe surgical care. The biochemical basis of emphasizing temperature regulation is sound, and ample evidence shows the frank physiologic derangements seen when biological processes occur at suboptimal temperature. It is also recognized that patients tend to do better when warmed during the perioperative period, suggesting that warming devices are an important and essential adjunct to good perioperative care. Clinicians, researchers, and policymakers must be careful in how they apply these well-supported findings to process metrics in an era of limited resources with increasingly stringent quality guidelines and outcomes measures. Discrete temperature targets in current measures are not supported by the existing literature. Not only do these targets artificially anchor clinicians to temperature values with an inadequate scientific basis but they demand intensive resources from health institutions that could potentially be better used on quality requirements with stronger evidence of their ultimate effect on patient care.

The impact of glycosylated hemoglobin and diabetes mellitus on wound-healing complications and infection after foot and ankle surgery

BACKGROUND

The relationship between hyperglycemia and adverse outcomes after surgery has been widely documented. Long-term glucose control has been recognized as a risk factor for postoperative complications. In the foot and ankle literature, long-term glycemic control as a potential perioperative risk factor is not well studied. Our goal was to investigate whether hemoglobin A1c (HbA1c) level was independently associated with postoperative complications in a retrospective cohort study.

METHODS

Three hundred twenty-two patients with a diagnosis of diabetes mellitus were enrolled in the study to assess risk factors associated with postoperative foot and ankle surgery complications.

RESULTS

Bivariate analyses showed that HbA1c level and having at least one comorbidity were associated with postoperative infections. However, after adjusting for other covariates, the only significant factor was HbA1c level, with each increment of 1% increasing the odds of infection by a factor of 1.59 (95% confidence interval [CI], 1.28-1.99). For postoperative wound-healing complications, bivariate analyses showed that body mass index, having at least one comorbidity, and HbA1c level were significant factors. After adjusting for other covariates, the only significant factors for developing postoperative wound complications were having at least one comorbidity (odds ratio, 2.03; 95% CI, 1.22-3.37) and HbA1c level (each 1% increment) (odds ratio, 1.25; 95% CI, 1.02-1.53).

CONCLUSIONS

In this retrospective study, HbA1c level had the strongest association with postoperative foot and ankle surgery complications in patients with diabetes.

Influence of oxygen on wound healing

Oxygen has an important role in normal wound healing. This article reviews the evidence concerning the role of oxygen in wound healing and its influence on the different stages of wound healing. The evidence reviewed has demonstrated that improving oxygenation may be helpful in limiting wound infection, although there is a lack of good quality studies on the role of oxygen in the proliferative phase and in reepithelialisation. Overall, the relationship between oxygen and wound healing is complex. Knowledge of this aspect is important as many treatment modalities for refractory wounds are based on these principles.

[Complications associated with inguinal orchiectomy and scrotal orchiectomy]

Inguinal excision of testis is technically an elementary surgical procedure. According to the indication (e.g., malignant tumors, infarction, inflammation), an inguinal or alternatively a transcrotal approach is possible. Despite its straightforwardness, surgery of the scrotum includes remarkable risks and complications such as postoperative hemorrhage, hematoma formation, infections, and disturbances of wound healing followed by insufficient unfavorable cosmetic results. Nerve injury may be accompanied by temporary or persistent paresthesias which have been documented in our patients undergoing orchiectomy.

Anesthesia, microcirculation, and wound repair in aging

Age-related changes in skin contribute to impaired wound healing after surgical procedures. Changes in skin with age include decline in thickness and composition, a decrease in the number of most cell types, and diminished microcirculation. The microcirculation provides tissue perfusion, fluid homeostasis, and delivery of oxygen and other nutrients. It also controls temperature and the inflammatory response. Surgical incisions cause further disruption of the microvasculature of aged skin. Perioperative management can be modified to minimize insults to aged tissues. Judicious use of fluids, maintenance of normal body temperature, pain control, and increased tissue oxygen tension are examples of adjustable variables that support the microcirculation. Anesthetic agents influence the microcirculation of a combination of effects on cardiac output, arterial pressure, and local microvascular changes. The authors examined the role of anesthetic management in optimizing the microcirculation and potentially improving postoperative wound repair in older persons.

Adipose-derived mesenchymal stem cells from ventral hernia repair patients demonstrate decreased vasculogenesis

INTRODUCTION

In adipose tissue healing, angiogenesis is stimulated by adipose-derived stromal stem cells (ASCs). Ventral hernia repair (VHR) patients are at high risk for wound infections. We hypothesize that ASCs from VHR patients are less vasculogenic than ASCs from healthy controls.

METHODS

ASCs were harvested from the subcutaneous fat of patients undergoing VHR by the component separation technique and from matched abdominoplasty patients. RNA and protein were harvested on culture days 0 and 3. Both groups of ASCs were subjected to hypoxic conditions for 12 and 24 hours. RNA was analyzed using qRT-PCR, and protein was used for western blotting. ASCs were also grown in Matrigel under hypoxic conditions and assayed for tubule formation after 24 hours.

RESULTS

Hernia patient ASCs demonstrated decreased levels of VEGF-A protein and vasculogenic RNA at 3 days of growth in differentiation media. There were also decreases in VEGF-A protein and vasculogenic RNA after growth in hypoxic conditions compared to control ASCs. After 24 hours in hypoxia, VHR ASCs formed fewer tubules in Matrigel than in control patient ASCs.

CONCLUSION

ASCs derived from VHR patients appear to express fewer vasculogenic markers and form fewer tubules in Matrigel than ASCs from abdominoplasty patients, suggesting decreased vasculogenic activity.

Anaesthetic perioperative management of patients with pancreatic cancer

Pancreatic cancer remains a significant and unresolved therapeutic challenge. Currently, the only curative treatment for pancreatic cancer is surgical resection. Pancreatic surgery represents a technically demanding major abdominal procedure that can occasionally lead to a number of pathophysiological alterations resulting in increased morbidity and mortality. Systemic, rather than surgical complications, cause the majority of deaths. Because patients are increasingly referred to surgery with at advanced ages and because pancreatic surgery is extremely complex, anaesthesiologists and surgeons play a crucial role in preoperative evaluations and diagnoses for surgical intervention. The anaesthetist plays a key role in perioperative management and can significantly influence patient outcome. To optimise overall care, patients should be appropriately referred to tertiary centres, where multidisciplinary teams (surgical, medical, radiation oncologists, gastroenterologists, interventional radiologists and anaesthetists) work together and where close cooperation between surgeons and anaesthesiologists promotes the safe performance of major gastrointestinal surgeries with acceptable morbidity and mortality rates. In this review, we sought to provide simple daily recommendations to the clinicians who manage pancreatic surgery patients to make their work easier and suggest a joint approach between surgeons and anaesthesiologists in daily decision making.

The association of perioperative dexamethasone, smoking and alcohol abuse with wound complications after laparotomy

BACKGROUND

A number of perioperative risk factors may suppress the immune system and contribute to the development of post-operative complications. The association between surgical site infection (SSI) and other wound-related complications resulting from immunosuppression through either perioperative administration of dexamethasone, pre-operative smoking or alcohol abuse is, however, uncertain.

METHODS

This study was a post hoc analysis of data from the PROXI randomized trial in 1386 patients who underwent emergency or elective laparotomy. We assessed the associations of use of dexamethasone, smoking status and alcohol abuse with the primary outcome, being a composite of SSI, anastomotic leak, wound dehiscence, burst abdomen and 30-day mortality.

RESULTS

The primary outcome occurred in 21% of patients receiving dexamethasone versus 28% of patients not receiving dexamethasone, and this was not statistically significant when adjusting for stratification variables originally used in the PROXI trial [OR 0.90, 95% CI (0.65-1.24)]. In smokers, the primary outcome occurred in 32%, compared with 23% of non-smokers (P = 0.0001). Smokers also had a higher frequency of SSI (25% vs 17%, P < 0.0001) and burst abdomen (3.8% vs 2.4%, P = 0.04). In alcohol abusers, the primary outcome occurred in 48%, compared with 25% in patients who did not abuse alcohol (P = 0.0006). Burst abdomen occurred more commonly in alcohol abusers (15% vs 2.3%, P < 0.0001).

CONCLUSION

Perioperative administration of dexamethasone was not significantly associated with SSI or other wound-related complications. Conversely, smoking and alcohol abuse were both significant predictors of the primary outcome consisting of wound-related complications and mortality.

Effects of intra-operative end-tidal carbon dioxide levels on the rates of post-operative complications in adults undergoing general anesthesia for percutaneous nephrolithotomy: A clinical trial

Background:

A retrospective study has shown lesser days of hospital stay in patients with increased levels of intra-operative end-tidal carbon dioxide (ETCO₂). It is probable that hypercapnia may exert its beneficial effects on patients’ outcome through optimization of global hemodynamic and tissue oxygenation, leading to a lower rate of post-operative complications. This study was designed to test the hypothesis that higher values of intra-operative ETCO₂ decrease the rate of post-operative complications.

Materials and Methods:

In this randomized, double-blind clinical trial, 78 adult patients scheduled for percutaneous nephrolithotomy (PCNL) were prospectively enrolled and randomly divided into three groups. ETCO₂ was set and maintained throughout the procedure at 31-33, 37-39 and 43-45 mmHg in the hypocapnia, normocapnia and hypercapnia groups, respectively. The rates of post-operative complications were compared among the three groups.

Results:

Seventy-five patients completed the study (52 male and 23 female). Ten (38.5%), four (16%) and two (8.3%) patients developed post-operative vomiting in the hypocapnia, normocapnia and hypercapnia groups, respectively (P = 0.025). The nausea score was significantly lower in the hypercapnic group compared with the other groups (3.9 ± 1.8, 3.2 ± 2.1 and 1.3 ± 1.8 in the hypocapnia, normocapnia and hypercapnia groups, respectively; P = 0.000). Time to return of spontaneous respiration and awakening were significantly decreased in the hypercapnia group compared with the other groups (P < 0.01).

Conclusion:

Mild intra-operative hypercapnia has a protecting effect against the development of post-operative nausea and vomiting and decreases the duration of emergence and recovery from general anesthesia.

Obesity and surgical wound healing: a current review

Objective. The correlation between obesity and deficient wound healing has long been established. This review examines the current literature on the mechanisms involved in obesity-related perioperative morbidity. Methods. A literature search was performed using Medline, PubMed, Cochrane Library, and Internet searches. Keywords used include obesity, wound healing, adipose healing, and bariatric and surgical complications. Results. Substantial evidence exists demonstrating that obesity is associated with a number of postoperative complications. Specifically in relation to wound healing, explanations include inherent anatomic features of adipose tissue, vascular insufficiencies, cellular and composition modifications, oxidative stress, alterations in immune mediators, and nutritional deficiencies. Most recently, advances made in the field of gene array have allowed researchers to determine a few plausible alterations and deficiencies in obese individuals that contribute to their increased risk of morbidity and mortality, especially wound complications. Conclusion. While the literature discusses how obesity may negatively affect health on various of medical fronts, there is yet to be a comprehensive study detailing all the mechanisms involved in obesity-related morbidities in their entirety. Improved knowledge and understanding of obesity-induced physiological, cellular, molecular, and chemical changes will facilitate better assessments of surgical risks and outcomes and create efficient treatment protocols for improved patient care of the obese patient population.

Prevention of surgical site infections

In the current era of pay-for-performance standards, the incidence of surgical site infections is increasingly becoming an institutional marker of quality assurance. Surgical site infections lead to increased morbidity and mortality in the surgical population and contribute to an already rising healthcare cost. As a result, the surgical community goes to great lengths to prevent this costly and occasionally lethal complication. Many practices are evidence based, however, many are not. In this article, the most commonly used preventive strategies in practice today and the evidence behind each are reviewed. In addition, an overview of the epidemiology, pathophysiology and microbiology of surgical site infections will be provided.

Perioperative supplemental oxygen to reduce surgical site infection after open fixation of high-risk fractures: a randomized controlled pilot trial

BACKGROUND

Higher concentrations of fraction of inspired oxygen (FIO2) have been shown to be associated with lower risk for surgical site infection in multiple studies outside the domain of orthopedic surgery. We evaluated the efficacy of high FIO2 administered during the perioperative period to reduce the rate of surgical site infection after open fixation of lower-extremity fractures at high risk of infection.

METHODS

We conducted a randomized controlled, parallel design, double-blind study. Patients sustaining high-energy tibial plateau, tibial pilon, and calcaneus fractures treated in a staged fashion were selected for enrollment because these injuries are associated with high risk of infection. The study population included 222 patients with 235 fractures. Consenting patients were randomized by random number sequence to either the treatment or the control group. Treatment group patients received 80% FIO2 intraoperatively and for 2 hours afterward. Control group patients received 30% FIO2 during the same period. Surgeons, patients, and personnel who performed wound assessments were blinded to group assignment. The primary outcome measure was surgical site infection as defined by the Centers for Disease Control criteria for postoperative wound infection.

RESULTS

The overall rates of postoperative surgical site infection were 12% (14 of 119 fractures) in the treatment group and 16% (19 of 116 fractures) in the control group (p = 0.31). Multivariate analysis, accounting for risk factors for infection, yielded the closest to a statistically significant reduction in the odds of infection with treatment (odds ratio, 0.54; p = 0.17). No treatment-associated events were observed.

CONCLUSION

Use of a high concentration of FIO2 during the perioperative period is safe and shows a trend toward reduction of surgical site infection in patients undergoing open operative fixation of high-energy traumatic lower-extremity fractures. Further study in a larger patient population is indicated.

LEVEL OF EVIDENCE

Therapeutic study, level III.

Continuous topical oxygen for the treatment of chronic wounds: a pilot study

Oxygen is essential for all stages of wound healing. Previous research has shown topical administration of oxygen to have positive effects on wound healing. In this study, the application of transdermal continuous topical oxygen therapy (TCOT) was evaluated for its effect on chronic wound healing in 9 patients. After 4 weeks of treatment, mean wound surface area and wound infection checklist scores were significantly reduced. Signs of bacterial damage were also reduced. Findings from this study suggest TCOT may be beneficial in promoting chronic wound healing.

Pain in Intensive Care: A Personalised Healthcare Approach

For patients admitted to intensive care, pain is a common experience with potentially significant consequences. Pain management needs to evolve from the traditional ‘one-size-fits-all’ plan to a more personalised approach. This can be achieved by appreciating the numerous potential causes of pain, using appropriate assessment tools, utilising a range of potential treatment options and addressing the challenges associated with pain management in this heterogeneous population. At this point a truly multimodal, multidisciplinary management plan can be implemented, aimed at improving pain control and ultimately patient outcomes.

Oxygen and wound care: a review of current therapeutic modalities and future direction

While the importance of oxygen to the wound healing process is well accepted, research and technological advances continue in this field and efforts are ongoing to further utilize oxygen as a therapeutic modality. In this paper, the authors briefly review the role of oxygen in wound healing and discuss the distinct mechanism of action as well as the advantages and disadvantages of the three major oxygen-based therapies currently in clinical use (Hyperbaric Oxygen and Topical Oxygen and Continuous Diffusion of Oxygen), as well as review the existing literature regarding these distinct therapeutic modalities.

Leukocyte DNA Damage and Wound Infection after Nitrous Oxide Administration

Background:

Nitrous oxide inactivates methionine synthase and may lead to DNA damage and wound infection. By using single-cell gel electrophoresis (comet assay), the authors determined the effect of nitrous oxide on DNA damage in circulating leukocytes.

Methods:

In this double-blind, randomized controlled trial, 91 patients undergoing major colorectal surgery were randomized to receive 70% nitrous oxide (n = 31) or nitrous oxide-free anesthesia using 30 (n = 30) or 80% (n = 30) oxygen. Venous blood was collected before and 24 h after surgery. The primary outcome was extent of DNA damage, quantified as the percentage of DNA staining intensity in the comet tail using digital fluorescence microscopy. Incidence of postoperative wound infection was also recorded.

Results:

Nitrous oxide exposure was associated with a two-fold increase in the percentage of DNA intensity in tail (P = 0.0003), but not in the 30 (P = 0.181) or 80% oxygen groups (P = 0.419). There was a positive correlation between the duration of nitrous oxide exposure and extent of DNA damage, r = 0.33, P = 0.029. However, no correlation was observed in nitrous oxide-free patients. The proportions of postoperative wound infection, using the Centers for Disease Control and Prevention criteria, were 19.4% (6 of 31) in the 70% nitrous oxide group and 6.7% (2 of 30) in both the 30 and 80% oxygen groups, P = 0.21. An increase in DNA damage was associated with a higher risk of wound infection, adjusted odds ratio (95% CIs): 1.19 (1.07–1.34), P = 0.003.

Conclusions:

Nitrous oxide increased DNA damage compared with nitrous oxide-free anesthesia and was associated with postoperative wound infection.

Risk factor of surgical site infection after pancreaticoduodenectomy

BACKGROUND

Although surgical site infection (SSI) following pancreaticoduodenectomy is a common complication, the risk factors remain unclear.

PATIENTS AND METHODS

A retrospective study of 408 consecutive patients undergoing pancreaticoduodenectomy was conducted and the risk factors for SSI were assessed. The bacterial composition was also analyzed.

RESULTS

Sixty-one patients developed incisional SSI, and 195 developed organ/space SSI. A multivariate analysis identified that length of operation>480 min (odds ratio [OR] 3.22), main pancreatic duct (MPD)≤3 mm (OR 2.18), and abdominal wall thickness>10 mm (OR 2.16) were significant risk factors for incisional SSI. The development of pancreatic fistula (OR 7.56), use of semi-closed drainage system (OR 3.68), body mass index>23.5 kg/m2 (OR 3.04), MPD≤3 mm (OR 2.21), and length of operation>480 min (OR 1.78) were significantly associated with organ/space SSI. Bacterial isolation at the SSI foci revealed that gut-derived micro-organisms were the predominant bacterial species.

CONCLUSIONS

The presence of pancreatic fistula was the strongest risk factor for organ/space SSI. Efforts to reduce the development of pancreatic fistulas, to decrease length of operation, and to use a closed drainage system would decrease the incidence of SSI following pancreaticoduodenectomy. If SSI that requires antibacterial treatment occurs, then the treatment should target enterobacteria.

Dopexamine can attenuate the inflammatory response and protect against organ injury in the absence of significant effects on hemodynamics or regional microvascular flow

Introduction

The effects of dopexamine, a β2-agonist, on perioperative and sepsis-related hemodynamic, microvascular, immune, and organ dysfunction are controversial and poorly understood. We investigated these effects in a rodent model of laparotomy and endotoxemia.

Methods

In two experiments, 80 male Wistar rats underwent laparotomy. In 64 rats, this was followed by administration of endotoxin; the remainder (16) underwent sham endotoxemia. Endotoxemic animals received either dopexamine at 0.5, 1, or 2 μg/kg/min or 0.9% saline vehicle (controls) as resuscitation fluid. The effects of dopexamine on global hemodynamics, mesenteric regional microvascular flow, renal and hepatic function and immune activation were evaluated.

Results

Endotoxin administration was associated with a systemic inflammatory response (increased plasma levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, and IL-10, as well as cell-adhesion molecules CD11a and CD11b), and increased pulmonary myeloperoxidase (MPO) activity (indicating pulmonary leukocyte infiltration), whereas biochemical changes demonstrated lactic acidosis with significant renal and hepatic injury. Dopexamine administration was associated with less-severe lactic acidosis (pooled dopexamine versus controls, (lactate, 2.2 mM ± 0.2 mM versus 4.0 mM ± 0.5 mM; P < 0.001) and reductions in the systemic inflammatory response (pooled dopexamine versus control, 4 hour (TNF-α): 324 pg/ml ± 93 pg/ml versus 97 pg/ml ± 14 pg/ml, p < 0.01), pulmonary myeloperoxidase (MPO) activity, and hepatic and renal injury (pooled dopexamine versus control (ALT): 81 IU/L ± 4 IU/L versus 138 IU/L ± 25 IU/L; P < 0.05; (creatinine): 49.4 μM ± 3.9 μM versus 76.2 μM ± 9.8 μM; P < 0.005). However, in this study, clinically relevant doses of dopexamine were not associated with clinically significant changes in MAP, CI, or gut regional microvascular flow.

Conclusions

In this model, dopexamine can attenuate the systemic inflammatory response, reduce tissue leukocyte infiltration, and protect against organ injury at doses that do not alter global hemodynamics or regional microvascular flow. These findings suggest that immunomodulatory effects of catecholamines may be clinically significant when used in critically ill surgical patients and are independent of their hemodynamic actions.