Tissue oxygenation, anemia, and perfusion in relation to wound healing in surgical patients

Broad-Spectrum Inhibition of the CC-Chemokine Class Improves Wound Healing and Wound Angiogenesis

Angiogenesis is involved in the inflammation and proliferation stages of wound healing, to bring inflammatory cells to the wound and provide a microvascular network to maintain new tissue formation. An excess of inflammation, however, leads to prolonged wound healing and scar formation, often resulting in unfavourable outcomes such as amputation. CC-chemokines play key roles in the promotion of inflammation and inflammatory-driven angiogenesis. Therefore, inhibition of the CC-chemokine class may improve wound healing. We aimed to determine if the broad-spectrum CC-chemokine inhibitor “35K” could accelerate wound healing in vivo in mice. In a murine wound healing model, 35K protein or phosphate buffered saline (PBS, control) were added topically daily to wounds. Cohorts of mice were assessed in the early stages (four days post-wounding) and in the later stages of wound repair (10 and 21 days post-wounding). Topical application of the 35K protein inhibited CC-chemokine expression (CCL5, CCL2) in wounds and caused enhanced blood flow recovery and wound closure in early-mid stage wounds. In addition, 35K promoted neovascularisation in the early stages of wound repair. Furthermore, 35K treated wounds had significantly lower expression of the p65 subunit of NF-κB, a key inflammatory transcription factor, and augmented wound expression of the pro-angiogenic and pro-repair cytokine TGF-β. These findings show that broad-spectrum CC-chemokine inhibition may be beneficial for the promotion of wound healing.

Intraoperative Hypothermia in Total Hip and Knee Arthroplasty

Total hip arthroplasty (THA) and total knee arthroplasty (TKA) are common and successful orthopedic procedures, and as their frequency continues to increase substantially, the focus on limiting perioperative complications heightens. Intraoperative normothermia is recommended to minimize additional complications, but limited evidence exists regarding the effect of hypothermia on orthopedic patients. The purpose of this retrospective study was to determine the incidence of perioperative hypothermia in the setting of TKA and THA, and to evaluate its impact on complications and outcomes. The clinical records of 2580 consecutive patients who underwent TKA or THA at a single institution between January 1, 2011, and December 31, 2013 were reviewed. After excluding patients with complex or revision procedures, a total of 2397 patients comprised the study population. Patient demographic data, surgery-specific data, postoperative complications, length of hospital stay, and 30-day readmission were recorded. Patients with a mean intraoperative temperature less than 36°C were identified as hypothermic. Statistical analysis evaluated associations with hypothermia and the effect on complications and outcomes. The incidence of mean intraoperative hypothermia was 37%, 43.9%, and 32.6% for arthroplasty, THA, and TKA, respectively. General anesthesia was significantly associated with hypothermia (P<.001). Women and THA patients were at higher risk for hypothermia. In the arthroplasty and THA cohorts, longer operating room time and re-warmer use were associated with hypothermia (P=.010). Overall, hypothermia was associated with increased estimated blood loss, but no increase in associated transfusion was demonstrated (P=.006). Hypothermia was not associated with postoperative complications. [Orthopedics. 2017; 40(1):56-63.].

Intraoperative Hypothermia During Surgical Fixation of Hip Fractures

Hip fractures are common orthopedic injuries and are associated with significant morbidity/mortality. Intraoperative normothermia is recommended by national guidelines to minimize additional morbidity/mortality, but limited evidence exists regarding hypothermia's effect on orthopedic patients. The purpose of this study was to determine the incidence of intraoperative hypothermia in patients with operatively treated hip fractures and evaluate its effect on complications and outcomes. Retrospective chart review was performed on clinical records from 1541 consecutive patients who sustained a hip fracture and underwent operative fixation at the authors' institution between January 2005 and October 2013. A total of 1525 patients were included for analysis, excluding those with injuries requiring additional surgical intervention. Patient demographic data, surgery-specific data, postoperative complications, length of stay, and 30-day readmission were recorded. Patients with a mean intraoperative temperature less than 36°C were identified as hypothermic. Statistical analysis with univariate and multivariate logistic regression modeling evaluated associations with hypothermia and effect on complications/outcomes. The incidence of intraoperative hypothermia in operatively treated hip fractures was 17.0%. Hypothermia was associated with an increase in the rate of deep surgical-site infection (odds ratio, 3.30; 95% confidence interval, 1.19-9.14; P=.022). Lower body mass index and increasing age demonstrated increased association with hypothermia (P=.004 and P=.005, respectively). To the authors' knowledge, this is the first and largest study analyzing the effect of intraoperative hypothermia in orthopedic patients. In patients with hip fractures, the study's findings confirm evidence found in other surgical specialties that hypothermia may be associated with an increased risk of deep surgical-site infection and that lower body mass index and increasing age are risk factors for intraoperative hypothermia. [Orthopedics. 2016; 39(6):e1170-e1177.].

Hyperbaric oxygen therapy promotes wound repair in ischemic and hyperglycemic conditions, increasing tissue perfusion and collagen deposition

The treatment of chronic wounds remains inconsistent and empirical. Hyperbaric oxygen therapy (HBOT) is a promising method to improve wound repair but there is still a lack of understanding of its mechanisms of action and its indications are not yet clearly defined. We studied the effects of HBOT in four different wound conditions by inflicting bilateral wounds on the dorsal aspect of the feet of nonischemic or ischemic limbs in normoglycemic or hyperglycemic rats. To create an ischemic condition, arterial resection was performed unilaterally. Forty-four animals received HBOT five times a week until complete wound closure. Wound repair was compared with 44 rats receiving standard dressing only. HBOT increased blood flow and accelerated wound closure in ischemic and hyperglycemic wounds, most significantly when the two conditions were combined. Wound contraction and reepithelialization were similarly stimulated by HBOT. The acceleration of wound contraction was not associated with increased myofibroblasts expression, nor fibroblast recruitment or higher cell count in the granulation tissue. Of note, we observed a significant increase in collagen deposition in early time points in ischemic wounds receiving HBOT. This data emphasizes that an early application of HBOT might be crucial to its efficacy. We concluded that wounds where ischemia and hyperglycemia are combined, as it is often the case in diabetic patients, have the best chance to benefit from HBOT.

Skin staples versus intradermal wound closure following primary hip arthroplasty: a prospective, randomised trial including 231 cases

Intradermal wound closure is controversial in primary total hip arthroplasty. Randomised, controlled trials in wound closure following a total hip arthroplasty (THA) are scarce. Our hypothesis was that skin staples closure would be related to a similar complication rate and operative time as intradermal closure with polypropylene. From September 2011 to May 2012, 231 THAs in 219 patients with an average age of 62 years old (range: 21-91) were performed. No differences were observed in both groups according to sex, age, BMI and comorbidities (p = 0,82). Cases were divided into 3 groups according to medical factors that influence wound healing: group 1 (no medical history, 70.5%), group 2 (diabetes, tobacco smokers, obesity, corticosteroids, rheumatoid disease, 25%) and group 3 (organ transplantation, neoplastic patients or 2 or factors of group 2, 4.5%). Once randomised using a computer-generated method, all patients remained within the group to which they were allocated to wound closure with skin staples (Leukosan® SkinStapler PTW-35, BSN, Germany) that were used in 112 THAs in 105 patients (48%), or continuous 3.0 intradermal non-absorbable polypropylene suture (Prolene™ 0, Ethicon Inc. Somerville, New Jersey, USA) in 119 THA´s in 115 patients (52%). A 3.8% wound complication rate was observed in this series, with a 2.1% complication rate for the group that was closed with skin staples and a 1.7% rate for the group with intradermal suture (p = 0.7). All the complications were treated conservatively except for one acute deep infection (0.4%) that was successfully treated with debridement, component retention and intravenous antibiotics. There were no differences in both groups related to operative time or wound length.In these series of primary elective THAs, skin staples were associated with a similar complication rate to an intradermal closure technique.

Intraoperative Fluid Excess Is a Risk Factor for Pancreatic Fistula after Partial Pancreaticoduodenectomy

Background. After pancreaticoduodenectomy (PD), pancreatic fistulas (PF) are a frequent complication. Infusions may compromise anastomotic integrity. This retrospective analysis evaluated associations between intraoperative fluid excess and PF. Methods. Data on perioperative parameters including age, sex, laboratory findings, histology, infusions, surgery time, and occurrence of grade B/C PF was collected from all PD with pancreaticojejunostomy (PJ) performed in our department from 12/2011 till 02/2015. The glomerular filtration rate (GFR), infusion rate, and the ratio of both and its association with PF were calculated. ROC analysis was employed to identify a threshold. Results. Complete datasets were available for 83 of 86 consecutive cases. Median age was 66 years (34–84; 60% male), GFR was 93 mL/min (IQR 78–113), and surgery time was 259 min (IQR 217–307). Intraoperatively, 13.6 mL/min (7–31) was infused. In total, n = 18 (21%) PF occurred. When the infusion : GFR ratio exceeded 0.15, PF increased from 11% to 34% (p = 0.0157). No significant association was detected for any of the other parameters. Conclusions. This analysis demonstrates for the first time an association between intraoperative fluid excess and PF after PD with PJ even in patients with normal renal function. A carefully patient-adopted fluid management with due regard to renal function may help to prevent postoperative PF.

The Clinical Role of Intraoperative Core Temperature in Free Tissue Transfer

BACKGROUND

Lengthy microvascular procedures carry hypothermia risk, yet limited published data evaluate the overall impact of core temperature on patient and flap morbidity. Although hypothermia may contribute to complications, warming measures are challenged by conflicting reports of intraoperative hypothermia improving anastomotic patency.

METHODS

A retrospective review included all free flaps performed by plastic surgeons at an academic medical center from December 2005 to December 2010. Intraoperative core temperatures were measured by esophageal probe, and median values recorded over 5-minute intervals yielded a case mean (Tavg), maximum (Tmax), and nadir (Tmin). Outcomes included flap failure, pedicle thrombosis, recipient site infection and complications associated with patient, and flap morbidity. Analysis used Student t test, Fisher exact test, Probit, and logistic regression.

RESULTS

Of 156 consecutive free tissue transfers, the median Tavg, Tmax, and Tmin were 36.5°C, 37.1°C, and 35.8°C, respectively. The flap failure rate was 7.7% (12/156) and pedicle thrombosis occurred in 9 (6%) cases. Core temperatures did not associate with overall flap failure or pedicle thrombosis but recipient site infection occurred in 21 (13%) patients who had significantly lower mean core temperatures (Tavg=36.0°C, P<0.01). Lower Tavg and Tmax significantly predicted recipient site infection (P<0.01 and P<0.05, respectively). Cut-point analysis revealed significant increases in recipient site infection risk at Tavg less than 37.0°C (P=0.026) and Tmin less than or equal to 34.5°C (P=0.020).

CONCLUSIONS

Intraoperative hypothermia posed significant risk of flap infection with no benefit to anastomotic patency in free tissue transfer.

Increased oxygen exposure alters collagen expression and tissue architecture during ligature-induced periodontitis

BACKGROUND AND OBJECTIVE

The aim of this study was to evaluate the effects of increased oxygen availability on gene expression and on collagen deposition/maturation in the periodontium following disease.

MATERIAL AND METHODS

Male Wistar rats had ligatures placed around their molars to induce periodontal disease, and a subset of animals underwent hyperbaric oxygen (HBO) treatment for 2 h twice per day. At 15 and 28 d, tissue gene expression of COL1A1, transforming growth factor-β1 and alkaline phosphatase was determined; other histological samples were stained with Picrosirius red to evaluate levels of collagen deposition, maturation and thickness.

RESULTS

In animals that underwent HBO treatment, type I collagen expression was higher and collagen deposition, maturation and thickness were more robust. Reduced mRNA levels of transforming growth factor-beta1 and alkaline phosphatase in HBO-treated rats on day 28 suggested that a quicker resolution in both soft tissue and bone remodeling occurred following oxygen treatment. No differences in inflammation were observed between groups.

CONCLUSIONS

The extracellular matrix regenerated more quickly in the HBO-treated group as evidenced by higher collagen expression, deposition and maturation.

The Effect of Early Postoperative Physical Activity on Tissue Oxygen and Wound Healing

Background. Supplemented postoperative activity was compared to standard activity for effects on wound healing, subcutaneous tissue perfusion, and oxygen (PscO2 ) following hip replacement (THR).

Methods. 58 patients were randomized to standard post-THR activity (N = 27) or supplemental activity (N = 31) (arm and leg exercises, walking protocol). PscO2 was measured with a microelectrode/tonometer system and perfusion determined by oxygen response. Healing was evaluated by (1) tissue cellularity, (2) mRNA for pro collagen, (3) hydroxyproline, and (4) DNA content obtained from a subcutaneous implant removed on the 7th postoperative day.

Results. Activity significantly increased DNA levels, but did not increase PscO2 , perfusion, cellularity, or collagen measures.

Conclusions. Healing measures were not improved with increased activity levels. However, activity did not reduce PscO2 or wound healing. The majority of patients adhered to additional activity and tolerated the protocol well. Increased activity was associated with earlier discharge, suggesting other recovery-related benefits.

Measurement of Peripheral Venous Oxygen Saturation in the Leg Using Near-Infrared Spectroscopy

Background:

It has been suggested that poor healing of wounds may be associated with reduced tissue oxygenation. A non-invasive method of assessing peripheral venous oxygenation has been investigated.

Method:

Changes in oxyhaemoglobin (O2Hb), deoxyhaemoglobin (HHb), oxidized cytochrome aa3 (cyt aa3) and total haemoglobin (tHb) were monitored in the left lower leg of seven healthy volunteers. A short period of venous occlusion was achieved by rapidly inflating a sphygmomanometer cuff placed around the leg to 60 mmHg. The changes in O2Hb and tHb, with respect to the baseline readings, were evaluated. PSvO2 was calculated from (ΔO2Hb/ΔtHb) × 100%.

Results:

From 17 sets of readings on the seven volunteers the median PSvO2 calculated was 64% (range 50–86%).

Conclusion:

This method appears to be a simple means of evaluating PSvO2. A change in cyt aa3 was often seen associated with the venous occlusion.

Fluid therapy in the perioperative setting-a clinical review

BACKGROUND

Perioperative hypovolemia and fluid overload have effects on both complications following surgery and on patient survival. Therefore, the administration of intravenous fluids before, during, and after surgery at the right time and in the right amounts is of great importance. This review aims to analyze the literature concerning perioperative fluid therapy in abdominal surgery and to provide evidence-based recommendations for clinical practice.

RESULTS

Preoperative oral or intravenous administration of carbohydrate containing fluids has been shown to improve postoperative well-being and muscular strength and to reduce insulin resistance. Hence, the intake of fluid (preferably containing carbohydrates) should be encouraged up to 2 h prior to surgery in order to avoid dehydration. Excessive intravenous fluid administration adds to tissue inflammation and edema formation, thereby compromising tissue healing. During major abdominal surgery a "zero-balance" intraoperative fluid strategy aims at avoiding fluid overload (and comparable to the so-called restrictive approach) as well as goal-directed fluid therapy (GDT). Both proved to significantly reduce postoperative complications when compared to "standard fluid therapy". Trials comparing "restrictive" or zero-balance and GDT have shown equal results, as long as fluid overload is avoided in the GDT group as well (categorized as "zero-balance GDT"). It is possible that high-risk surgical patients, such as those undergoing acute surgery, may benefit from the continuous monitoring of circulatory status that the GDT provides. Data on this group of patients is not available at present, but trials are ongoing.

CONCLUSION

In elective surgery, the zero-balance approach has shown to reduce postoperative complications and is easily applied for most patients. It is less expensive and simpler than the zero-balance GDT approach and therefore recommended in this review. In outpatient surgery, 1-2 L of balanced crystalloids reduces postoperative nausea and vomiting and improves well-being.

Rotator cuff tears: Review of epidemiology, clinical assessment and operative treatment

Rotator cuff tears (RTCs) are the most common cause of shoulder disability. There has been a proportional increase in the prevalence of RCT in accordance with the rising trend of an ageing population. In this article we review the current literature encompassing RCT epidemiology, risk factors and aetiopathogenesis. We also summarize the current diagnostic modalities, treatment options, rehabilitation and outcomes.

The Impact of Current Smoking and Smoking Cessation on Short-Term Morbidity Risk After Lumbar Spine Surgery

STUDY DESIGN

A retrospective review of prospectively collected data.

OBJECTIVE

The aim of this study was to determine the impact of current smoking or prior smoking cessation on 30-day morbidity risk following lumbar spine surgery.

SUMMARY OF BACKGROUND DATA

Prior studies have reported conflicting data regarding the impact of smoking on morbidity risk, and few studies have investigated smoking cessation.

METHODS

A large, multicenter, prospectively collected clinical registry was queried for all adult patients undergoing lumbar spine surgery in 2012 and 2013, and 35,477 cases were identified. Morbidity data are collected by on-site clinical personnel for 30 days postoperatively. Patients were divided into categories of "never-smoker," for patients with no reported cigarette use (n = 27,246), "former smoker," for patients who quit smoking more than 12 months before surgery (n = 562), and "current smoker," for patients still using cigarettes (n = 7669). A univariate analysis was conducted to identify un-adjusted differences in morbidity risk, and a multivariate analysis was conducted in an attempt to control for confounders.

RESULTS

In the multivariate analysis, current smokers had a significantly higher risk of both superficial surgical site infection and overall wound complications, than never-smokers (P < 0.05 for each). Current smokers also had a significantly higher risk of total 30-day morbidity (P = 0.04). There was a trend toward former smokers also having an increased risk, but this did not reach significance in any category. Patients with a pack-year smoking history of 1 to 20 pack-years and more than 40 pack-years both had a significantly higher risk of superficial surgical site infections (P < 0.05 for each).

CONCLUSION

Current smoking is associated with a small but significant increase in systemic morbidity and wound complications following elective lumbar spine procedures. Increasing pack year history was also associated with wound complication risk, suggesting a dose-related effect. The data provide preliminary support for future studies on smoking cessation.

LEVEL OF EVIDENCE

3.

Wound Healing Concepts in Clinical Practice of OMFS

BACKGROUND

Wound healing is a complex and dynamic process and a thorough knowledge of the basics of physiology of wound healing is a must to implement principles of chronic wound care. Understanding wound healing at multiple levels-biochemical, physiologic, cellular and molecular provides the surgeon with a framework for basing clinical decisions aimed at optimizing the healing response.

OBJECTIVE

This review article describes the classification of wounds and aims to highlight the fundamentals of wound repair, enumerating the dressings used commonly and also, the newer concepts of wound healing.

MATERIALS AND METHODS

Search engines and medical databases were tapped to gather information on the subject. Search words employed were "Wounds", "wounds in OSMF", "Wound healing", "Repair", "Dressings in OMFS".

RESULTS

The search resulted in total of 153 articles which we reviewed to add to the literature the concepts of wound healing and to throw some light on recent advances in wound care.

CONCLUSIONS

Wound healing remains a challenging clinical problem and correct, efficient wound management is essential to positively influence the wound healing course and reduce potential complications.

Effects of topical oxygen therapy on ischemic wound healing

[Purpose] This study evaluated the effects of topical oxygen therapy on the hind limb wounds of rats under ischemic conditions. [Subjects and Methods] Twelve injured rats were treated with topical oxygen on skin wounds located on the hind limb and compared with twelve injured control rats. Indexes including gross morphology of the wound, wound healing time, wound healing rate, and histological and immunohistochemical staining of sections of wound tissue were examined at different time points after intervention. [Results] The wound healing time was shorter in the topical oxygen therapy group than the control group. The wound healing rate and granulation tissue formation in the topical oxygen therapy group showed significant improvement on days 3, 7, and 14. Through van Gieson staining, the accumulation of collagen fiber in the topical oxygen therapy group was found to have improved when compared with the control group on day 7. Through semiquantitative immunohistochemical staining, many more new vessels were found in the topical oxygen therapy group compared with the model control group on day 7. [Conclusion] The results of the experiment showed that topical oxygen therapy improved ischemic wound healing.

The Chitranjan Ranawat Award: Running Subcuticular Closure Enables the Most Robust Perfusion After TKA: A Randomized Clinical Trial

BACKGROUND

Maintaining robust perfusion is an important physiologic parameter in wound healing. The effect of different closure techniques on wound perfusion after total knee arthroplasty (TKA) has not been established previously and may have implications for wound healing.

QUESTIONS/PURPOSES

We asked whether a running subcuticular, vertical mattress, or skin staple closure technique enables the most robust wound perfusion after TKA as measured by laser-assisted indocyanine green angiography (LA-ICGA) in patients without specific risk factors for wound healing complications.

METHODS

Forty-five patients undergoing primary TKA without comorbidities known to impact wound healing and perfusion were prospectively randomized to receive superficial skin closure with one of the following techniques: (1) running subcuticular (3-0 monofilament); (2) vertical mattress (2-0 nylon); or (3) skin staples. Twenty procedures were performed by RTT, 15 by RJS, and 10 by FHS. All surgeons used an anterior skin incision over the medial third of the patella in combination with a median parapatellar arthrotomy. Perfusion was assessed with a LA-ICGA device and software system immediately after closure to quantify fluorescence. Twenty-seven points were assessed immediately after closure in the operating room in each patient (nine along the incision and nine pairs medial and lateral to the incision). Mean incision perfusion was determined from the nine points along the incision with higher values indicating greater blood flow. Mean perfusion impairment was determined by calculating the difference between the nine pairs of surrounding skin and the nine points along the incision with smaller values indicating less perfusion impairment. These parameters were compared with analysis of variance (ANOVA) and subsequent pairwise comparisons with an unadjusted analysis as well as a multivariate analysis that adjusted for age, sex, and body mass index. Patients were followed for a mean of 7 months after surgery (range, 3-12 months) for possible incision-related complications. No patents were lost to followup.

RESULTS

Running subcuticular closure demonstrated the best overall perfusion. Mean incision perfusion in fluorescent units with SD was as follows: running subcuticular, 64 (16); vertical mattress, 32 (18); and staples, 19 (7) (ANOVA p < 0.001). The running subcuticular closure demonstrated the least impairment of perfusion among the closures compared. Mean perfusion impairment was as follows: running subcuticular, 21 (12); vertical mattress, 37 (24); and staples, 69 (27) (ANOVA p < 0.001). All Tukey-adjusted pairwise comparisons from both metrics likewise favored the subcuticular closure (p < 0.001) both before and after adjusting for age, sex, and body mass index. One patient in the vertical mattress cohort experienced a surgical site infection; no other wound-related complications were observed in this study.

CONCLUSIONS

The method of closure can influence skin and soft tissue perfusion after TKA. Running subcuticular closure enables the most physiologic robust blood flow, which may improve wound healing. However, the clinical importance of these findings remains uncertain, because patients in this study were selected because they lacked risk factors for wound healing complications. Studies with this modality in specific patient populations at higher risk for wound complications will be necessary to quantify the clinical advantage of using running subcuticular closure.

LEVEL OF EVIDENCE

Level I, therapeutic study.

Perioperative hypothermia: Causes, consequences and treatment

Perioperative hypothermia, core temperature below 36.0 °C, transpires due to disruption of thermoregulation by anesthesia coupled with cold exposure to procedural surroundings and cleansing agents. Although most publications have focused on thermoregulation disruption with general anesthesia, neuraxial anesthesia may also cause significant hypothermia. The clinical consequences of perioperative hypothermia are multiple and include patient discomfort, shivering, platelet dysfunction, coagulopathy, and increased vasoconstriction associated with a higher risk of wound infection. Furthermore, postoperative cardiac events occur at a higher rate; although it is unclear whether this is due to increased oxygen consumption or norepinephrine levels. Hypothermia may also affect pharmacokinetics and prolong postoperative recovery times and hospital length of stay. In order to combat perioperative hypothermia, many prevention strategies have been examined. Active and passive cutaneous warming are likely the most common and aim to both warm and prevent heat loss; many consider active warming a standard of care for surgeries over one hour. Intravenous nutrients have also been examined to boost metabolic heat production. Additionally, pharmacologic agents that induce vasoconstriction have been studied with the goal of minimizing heat loss. Despite these multiple strategies for prevention and treatment, hypothermia continues to be a problem and a common consequence of the perioperative period. This literature review presents the most recent evidence on the disruption of temperature regulation by anesthesia and perioperative environment, the consequences of hypothermia, and the methods for hypothermia prevention and treatment.

Evidence-Based Approach to Advanced Wound Care Products

There is increasing pressure from industry to use advanced wound care products and technologies. Many are very expensive but promise to reduce overall costs associated with wound care. Compelling anecdotal evidence is provided that inevitably shows wounds that failed all other treatments but responded positively to the subject product. Evidence-based medicine is the standard by which physician-scientists must make their clinical care decisions. In an attempt to provide policy makers with the most current evidence on advanced wound care products, the Department of Veteran Affairs conducted an Evidence-based Synthesis Program review of advanced wound care products. This paper suggests how to take this information and apply it to policy to drive evidence-based care to improve outcomes and fiduciary responsibility.

Effect of intraoperative PEEP application on colonic anastomoses healing: An experimental animal study

PURPOSE

This study aimed to assess the effect of intraoperative PEEP intervention on the healing of colonic anastomoses in rabbits.

MATERIALS AND METHODS

Thirty-two New Zealand type male rabbits were divided into two groups of sixteen animals each. Following ventilation with tracheostomy, colonic resection and anastomosis were performed in both groups. While 10 cm H2O PEEP level was applied in Group I (PEEP), Group II (ZEEP) was ventilated without PEEP throughout the surgery. Half of the both PEEP and ZEEP group animals were killed on the third postoperative day, while the remaining half on the seventh. Anastomotic bursting pressures, the tissue concentrations in hydroxyproline, and histological assessments were performed. Besides, intraoperative oxygen saturation and postoperative arterial blood gas parameters were also compared.

RESULTS

On the first postoperative day, both arterial oxygen tension (PO2) and oxygen saturation (SO2) in the PEEP group were significantly higher than in the ZEEP group. On the seventh postoperative day, the bursting pressures of the anastomoses were significantly higher in the PEEP group, however the hydroxyproline content was significantly lower in the PEEP group than that in the ZEEP group. At day 7, PEEP group was significantly associated with increased neoangiogenesis compared with the ZEEP group.

CONCLUSION

The anastomotic healing process is positively influenced by the intraoperative PEEP application.

In vitro and clinical experience of Cutimed Sorbact: the evidence base

In the previous chapter, Keith Cutting and James McGuire explored the link between infection and wound chronicity and explained how Cutimed Sorbact can be used to promote healing in chronic wounds. The following sections summarise the existing evidence for the Cutimed Sorbact range of dressings.

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.

A topical aqueous oxygen emulsion stimulates granulation tissue formation in a porcine second-degree burn wound

BACKGROUND

Oxygen is an essential substance for wound healing. Limited studies have shown that topical oxygen can influence healing. This study evaluated the effects of a Topical Oxygen Emulsion (TOE) on burn wound healing.

METHODS

A porcine second-degree burn wound model was used in the study. Burn wounds were randomly assigned to TOE, vehicle control, and no-treatment (air) groups. Effects of TOE on the granulation tissue formation and angiogenesis were studied using hematoxylin and eosin histological analysis. Protein production and gene expression of types I and III collagen and vascular endothelial growth factor (VEGF) were determined using immunofluorescent staining and Reverse Transcription and Polymerase Chain Reaction (RT-PCR), respectively.

RESULTS

The TOE treated wounds exhibited better angiogenesis and granulation tissue formation by histology examination. The immunofluorescence staining and RT-PCR analysis demonstrated that protein production and mRNA expression of VEGF and collagen III were significantly higher in TOE treatment group than vehicle alone and air control groups, while there was no significant difference in the level of collagen I.

CONCLUSIONS

Our data demonstrate that TOE enhances burn wound healing via stimulating the expression of VEGF and type III collagen and strongly indicates the potential use of TOE in wounds.

The effect of intraoperative fluid volume administration on pancreatic fistulas after pancreaticoduodenectomy

BACKGROUND

Fluid therapy may be one of the most controversial topics in perioperative management. However, data concerning the influence of perioperative fluid administration on complications after pancreaticoduodenectomy are sparse.

METHODS

A group of 147 patients underwent pancreaticoduodenectomy for benign or malignant pathology of the pancreas or the periampullary region between 2005 and 2009. Clinical data, overall morbidity, and long-term outcomes were recorded.

RESULTS

We categorized the patients into two groups according to intraoperative fluid volume administration: a low fluid volume group (LFVG, <8.2 ml kg(-1) hr(-1), n = 90) group, and a high fluid volume group (HFVG, ≥8.2 ml kg(-1) hr(-1), n = 57). In terms of colloid administration, the high fluid volume group received significantly more colloid both during the intraoperative period and 0-12 hr after surgery (p < .001 and p < .007, respectively). Pancreatic fistula rates were significantly greater in the high fluid volume group (p = .035). However, the long-term survival rate was not different between the two groups.

CONCLUSIONS

High intraoperative fluid volume administration is associated with an increased incidence of pancreatic fistulas after pancreaticoduodenectomy.

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.

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.

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.

Aging, hypercoagulability, and leg necrosis in critical limb ischemia

BACKGROUND

Aging is associated with changes in coagulation status and progression of arterial insufficiency. The purpose of this study was to identify interrelationships among aging, coagulation status, and leg necrosis in patients with critical limb ischemia (CLI).

METHODS

Between March 2010 and February 2013, 103 consecutive patients with CLI were enrolled in this study. Retrospective analyses were performed on patient characteristics including age, gender, the presence or the absence of leg necrosis, diabetes mellitus (DM), hypertension, and smoking, and preoperatively measured baseline coagulability factors, which included measurements of coagulation factors anticardiolipin antibodies IgG and IgM, lupus anticoagulant and factor 8, the fibrinolytic factor tissue plasminogen activator (t-PA), and natural anticoagulants proteins C and S and antithrombin III.

RESULTS

Among 103 patients with CLI, a total of 49 legs from 41 patients presented varying degrees of necrosis. CLI patients with DM and hypertension showed significantly increased incidences of leg necrosis compared with those without (P = 0.000, 0.039, respectively). Patients with CLI and leg necrosis were significantly older compared with the age of those without necrosis (P = 0.007). Blood levels of anticardiolipin antibodies IgG and IgM, factor 8, lupus anticoagulant, and t-PA tended to increase with age. However, blood levels of proteins C and S and antithrombin III decreased with patient age. Patients with CLI and leg necrosis showed significantly increased levels of lupus anticoagulant (P = 0.049) and significantly decreased levels of proteins C and S (P = 0.009 and 0.018, respectively) compared with patients without leg necrosis.

CONCLUSIONS

Patients with CLI and leg necrosis were significantly older compared with those without necrosis; similarly, our results revealed age-related hypercoagulability, with significantly elevated coagulation factor lupus anticoagulant and decreased natural anticoagulants protein C and S levels. From these observations, we conclude that age-related hypercoagulability may be an important mechanism that may facilitate leg necrosis in patients with CLI.

Influence of oxygen on wound healing dynamics in healing-impaired diabetic mice

A previous experiment using an in vivo mouse model has proved that hypoxia increased angiogenesis during wound healing. It was hypothesised that one of the mechanisms for wound healing impairment in diabetes includes insufficient angiogenic ability in response to hypoxia. The current study aims to investigate the influence of hypoxia on wound healing in diabetic mice. Oxygen-impermeable (hypoxic group) and -permeable membranes (normoxic group) were used to control topical oxygen tension. Membranes were applied to symmetrical excisional wounds on diabetic mice. Wound area, granulated tissue thickness, and vascular density were analyzed. As results, a decrease in wound size on day 7 was observed in the normoxic group (20.7 ± 3.64%) compared with the hypoxic group (34.1 ± 4.98%). The normoxic group also showed significantly thicker granulated tissue than the hypoxic group (225.7 ± 54.7 vs 128.7 ± 42.4 µm). There was no significant difference in mean vascular density between normoxic and hypoxic groups (0.046 ± 0.022 vs 0.038 ± 0.017 mm(2)/mm(2), p = 0.80). Contrary to healthy mice, diabetic mice have shown no enhancement of angiogenesis in hypoxic condition. The findings illustrate that neovascularisation in response to hypoxia is diminished in diabetic wounds.

The role of iron in the skin and cutaneous wound healing

In this review article we discuss current knowledge about iron in the skin and the cutaneous wound healing process. Iron plays a key role in both oxidative stress and photo-induced skin damage. The main causes of oxidative stress in the skin include reactive oxygen species (ROS) generated in the skin by ultraviolet (UVA) 320-400 nm portion of the UVA spectrum and biologically available iron. We also discuss the relationships between iron deficiency, anemia and cutaneous wound healing. Studies looking at this fall into two distinct groups. Early studies investigated the effect of anemia on wound healing using a variety of experimental methodology to establish anemia or iron deficiency and focused on wound-strength rather than effect on macroscopic healing or re-epithelialization. More recent animal studies have investigated novel treatments aimed at correcting the effects of systemic iron deficiency and localized iron overload. Iron overload is associated with local cutaneous iron deposition, which has numerous deleterious effects in chronic venous disease and hereditary hemochromatosis. Iron plays a key role in chronic ulceration and conditions such as rheumatoid arthritis (RA) and Lupus Erythematosus are associated with both anemia of chronic disease and dysregulation of local cutaneous iron hemostasis. Iron is a potential therapeutic target in the skin by application of topical iron chelators and novel pharmacological agents, and in delayed cutaneous wound healing by treatment of iron deficiency or underlying systemic inflammation.

A prospective case-control study of non-healing wounds of the lower limbs - the value of biopsies for ulcerating carcinoma

BACKGROUND

In some leg ulcer patients there is cancer that is responsible for lack of healing of such a wound.

AIM

This study was aimed at prospective analysis of histopathology of non-healing wounds (NHWs) in the patient presenting with high and low suspicion for ulcerating carcinoma.

MATERIAL AND METHODS

Forty patients with NHWs were enrolled and had been prospectively divided into two groups: 25 patients with high suspicion for ulcerating carcinoma according to their medical history and physical examination, and the second group of 15 patients without suspicion for malignancy (control group). All NHWs were photographed and underwent biopsies.

RESULTS

In the control group biopsies did not reveal cancers. On the contrary, in 10 patients (40%) from high suspicion group biopsies revealed cancers: seven basal cell carcinomas (BCCs), one - malignant melanoma, one - Bowen's disease and one - squamous cell carcinomas. Histopathology of six of seven BCCs suggested that non-healing benign wound might have preceded malignancy. We found that leg ulcers which were small (wound area less than 3 cm(2) ), longstanding (duration 24 ≤ weeks), presenting with granulation tissue covering ≥75% of the wound area, with a dull pink appearance of the granulation tissue, or an atypical clinical presentation, can actually be an ulcerating carcinoma. Dull pink granulation tissue or an atypical clinical presentation of ulceration, as a single clinical finding, suggested an underlying malignancy with a statistical significance (71.5% vs. 0%; P = 0.001 and 27.8% vs. 0%; P = 0.0049 respectively).

CONCLUSIONS

Prevalence of malignancy, primarily: BCCs in NHWs, may be higher than expected and clinical features suggestive of such a nature of ulcer are an indication for diagnostic biopsy.

Effect of the blood HbA1c level on surgical treatment outcomes of diabetics with ankle fractures

OBJECTIVE

To investigate whether blood haemoglobin A 1c (HbA1c) levels was predicative of diabetic patients' responsiveness to surgical treatment of ankle fractures.

METHODS

The relationship between blood HbA1c levels and surgical treatment outcomes of 21 diabetic patients undergoing open reduction internal fixation (ORIF) for ankle fractures was analyzed with Pearson correlation testing and t testing. All patients were treated with ORIF using standard surgical techniques. Treatment outcomes were defined using radiological outcome, the American Orthopaedic Foot and Ankle Score (AOFAS) ankle-hindfoot scale score, surgical revision rate, and complication rate.

RESULTS

HbA1c levels were found to have a statistically significant correlation with poor radiological outcomes (r = 0.547) and AOFAS ankle-hindfoot scores (r = -0.592). Additionally, though rates of poor radiological outcome, revision, and complication were high in the diabetic population as a whole, these rates were considerably higher among individuals with elevated HbA1c (≥6.5%) and considerably lower among individuals with lower HbA1c (<6.5%) levels.

CONCLUSION

Blood HbA1c levels appear to be predictive of risk and complication rates in the surgical treatment outcomes of diabetic patients with ankle fractures.

Biological effects of a disposable, canisterless negative pressure wound therapy system

OBJECTIVE

Recent developments of negative pressure wound therapy (NPWT) systems have focused on making pumps smaller, lighter, and more portable. The recently introduced PICO system manages wound fluid through a highly breathable film within the dressing, thereby negating the need for a canister, which allows greater mobility and patient concordance. The aim of this study is to compare the biological effects of this system compared to a traditional NPWT system.

METHODS

Laboratory tests were carried out to demonstrate the fluid handling properties of the PICO™ system. Porcine full thickness defect wounds and sutured incisional wounds were used to compare the biological effects. Wounds were treated with PICO dressings or traditional NPWT dressings and connected to either a PICO device or a traditional NPWT device.

RESULTS

The PICO dressing manages exudate predominantly through evaporative loss (up to 85% of all fluid entering the dressing). Both traditional NPWT and the PICO system maintained therapeutic levels of negative pressure in all wounds. Both NPWT systems produced similar effects on wound edge contraction and microvascular blood flow in defect wounds. No significant changes in blood flow or wound contraction were noted in incision wounds for any NPWT combinations tested.

CONCLUSIONS

The disposable, canisterless PICO NPWT system functions in the same manner as the traditional NPWT systems with regard to fluid handling, pressure transmission to the wound bed, tissue contraction, and changes in blood flow.

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.

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.

Abdominal surgical site infections: a prospective study of determinant factors in Harare, Zimbabwe

Surgical site infections (SSIs) are reported in lower frequencies in the developed countries than in the developing world. A prospective evaluation of risk factors in 285 patients undergoing abdominal surgery procedures in Zimbabwe was therefore undertaken. Overall infection rate was 26%. The age group 30-39 years had the highest number of dirty wounds and the highest rate of human immunodeficiency virus (HIV) infection. Multivariate regression analysis showed a correlation between wound class and SSI (P < 0·05). This was also noted for American Society of Anesthesiologists (ASA) score (P < 0·05). HIV-infected patients had 52% SSIs and non-infected patients had 26% (P < 0·05). Patients receiving blood transfusion had 51% SSIs and those not transfused had 17% (P < 0·01). Patients receiving pre- and intra-operative prophylactic antibiotics had 18% SSIs and those receiving postoperative administration had 37% (P < 0·01). Treatment ranged from dressings only in 11% to surgical intervention in 30% resulting in prolongation of median hospital stay from 8 to 18 days (P < 0·001). Mortality was 7%. High wound class, high ASA score, blood transfusion, HIV infection and delayed use of prophylactic antibiotics were risk factors for SSIs, resulting in surgical interventions, prolonged hospital stay and mortality.

Modulation of thioacetamide-induced liver fibrosis/cirrhosis by sildenafil treatment

Sildenafil citrate is a phosphodiesterase-5 inhibitor, approved for the treatment of erectile dysfunction. It enhances nitric-oxide-induced vasodilatation and it promotes angiogenesis. A relationship between angiogenesis and hepatic fibrosis has long been speculated, where the 2 are believed to progress together. In this study, the ability of sildenafil (10 mg·(kg body mass)(-1), orally, once daily) to prevent and also reverse liver fibrosis/cirrhosis experimentally induced by thioacetamide injection (200 mg·kg(-1), intraperitoneal (i.p.), 3 times·week(-1)) in male Sprague-Dawley rats has been investigated. Sildenafil administration, either to prevent or to reverse liver fibrosis/cirrhosis significantly improved the estimated hepatic functions, reduced hepatic hydroxyproline and, in turn, hepatic collagen content, as well as reducing serum levels of the pro-fibrogenic mediator transforming growth factor β1. In co-ordination with such improvement, fibrosis grades declined and fibrosis retracted. Herein, the observed results provide evidence for the potential therapeutic efficacy of sildenafil as an antifibrotic agent.

Clinical outcomes of WF10 adjunct to standard treatment of diabetic foot ulcers

OBJECTIVE

To study clinical outcomes and safety of WF I 0 as an adjunct to standard treatment for diabetic foot ulcers (DFU) and to determine the optimal number of WF I 0 cycles that should be administered.

METHOD

A prospective, open-label study of WF I 0 adjunct to standard treatment for severe DFU but salvageable foot was carried out between July 2009 and June 20 I 0. Patients were classified into three groups, according to common clinical presentations: neuropathic ulcer, ischaemic ulcer and severely infected ulcer. Ulcer assessments were monitored using the wound severity score (WSS; range 0-16).The clinical outcomes at 24 weeks were defined as 'good' (ulcer achieved endpoint [WSS=0-1 ]), 'fair'(improved from baseline [WSS=2-4]) and 'poor' (not improved or worsened [WSS > 4]).

RESULTS

From a total of 129 patients, 21 ( 16%) presented with neuropathic ulcers, 49 (38%) with ischaemic ulcers and 59 (46%) with severely infected ulcers.AII neuropathic ulcers achieved either a good or fair outcome, with 81% achieving a good outcome, as did 49% and 81% of ischaemic and severely infected ulcers, respectively. Minor amputations were necessary for 14 patients (I I%), but no major amputation was required. Twenty seven patients (21 %) had transient reduction of haematocrit after WF I 0 therapy. One hundred and one patients (78 %) received only I cycle of WF I 0.

CONCLUSION

WF I 0 as an adjunct to standard DFU treatment showed good clinical outcomes in the neuropathic ulcer group and the severely infected ulcer group. A side effect of WF I 0, transient reduction of haematocrit, was observed in 21% of patients. Most patients required only one cycle of WF I 0.

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.

Influence of oxygen on wound healing dynamics: assessment in a novel wound mouse model under a variable oxygen environment

Introduction

Although oxygen is essential for the wound healing process, tissue hypoxia is known to stimulate angiogenesis. To explore these inconsistent findings, we estimated the influence of the oxygen environment on wound healing with our original model.

Methods

Experiment 1 (Establishment of the model): To modify the topical oxygen tension, oxygen impermeable (polyvinylidene chloride) and permeable (polymethylpentene) membranes were applied to symmetrical excisional wounds in ddy mice (n = 6). Oxygen tension under the membrane was quantified with a device using photo-quenching technique. Experiment 2 (Influence of oxygen environment on wound healing): The wound area, granulation thickness and vascular density were analyzed under different oxygen environments (n = 24).

Results

Experiment 1: The permeable group maintained equivalent oxygen level to atmosphere (114.1±29.8 mmHg on day 7), while the impermeable group showed extremely low oxygen tension (5.72±2.99 mmHg on day 7). Accordingly, each group was defined as the normoxia group and the hypoxia group. Experiment 2: Percent decrease in wound size was significantly enhanced in the normoxia group (11.1±1.66% on day 7) in comparison with the hypoxia group (27.6±3.47% on day 7). The normoxia group showed significantly thicker granulation tissue than the hypoxia group (491.8±243.2 vs. 295.3±180.9 µm). Contrarily, the vascular density of the hypoxia group significantly increased on day 7 (0.046±0.025 vs. 0.011±0.008 mm²/mm²).

Conclusions

Our original model successfully controlled local oxygen concentration around the wound, and the hypoxic wounds showed increased angiogenesis but with a smaller amount of granulation tissue and delayed wound closure. Enhanced neovascularization in the hypoxic group likely implies compensative response to an insufficient ambient oxygen supply.

Stratification of Highest-Risk Patients with Chronic Skin Ulcers in a Stanford Retrospective Cohort Includes Diabetes, Need for Systemic Antibiotics, and Albumin Levels

Chronic nonsurgical skin wounds such as venous stasis and diabetic ulcers have been associated with a number of comorbid conditions; however, the strength of these associations has not been compared. We utilized the Stanford Translational Research Integrated Database Environment (STRIDE) system to identify a cohort of 637 patients with chronic skin ulcers. Preliminary analysis () showed that 49.7% of the patients had a poor prognosis such as amputation or a nonhealing ulcer for at least a year. Factors significantly associated () with these outcomes included diabetes mellitus, chronic kidney disease, peripheral neuropathy, peripheral arterial disease, and need for systemic antibiotics. Patients with poor outcomes also tended to have lower hemoglobin levels (), higher WBC levels (), and lower albumin levels (). On multivariate analysis, however, only diabetes mellitus (OR 5.87, 1.36–25.3), need for systemic antibiotics (OR 3.88, 1.06–14.2), and albumin levels (0.20 per unit, 0.07–0.60) remained significant independent predictors of poor wound-healing outcomes. These data identify patients at the highest risk for poor wound-healing and who may benefit the most from more aggressive wound care and treatment.

Transcutaneous oxygen tension in the anterior skin of the knee after minimal incision total knee arthroplasty

BACKGROUND

Delayed wound healing after total knee arthroplasty (TKA) can lead to devastating complications. The lateral flap is reported to be more hypoxic than the medial flap in conventional TKA. However, the surgical approach significantly affects the cutaneous blood supply. Our hypothesis was that postoperative oxygenation of the skin over the anterior knee would be different in minimal incision TKA.

METHODS

This prospective observation study included 21 patients who underwent minimal incision TKA. Transcutaneous oxygen tension (TcPO2) was measured perioperatively at four sites around the midline incision: superio-medial, superio-lateral, inferio-medial, and inferio-lateral. The ratio of the regional TcPO2 to the reference TcPO2 was calculated as the regional perfusion index (RPI). We compared the RPI among four sites and evaluated the association between the RPI and wound healing.

RESULTS

At all measurement sites, the RPI significantly decreased after surgery (days 1 and 7; p<0.01). On day 7, the RPI at inferio-medial and inferio-lateral sites were significantly lower than superio-medial and superio-lateral sites, respectively (p<0.05). No significant difference between the medial and lateral sites was observed. In three patients, delayed healing was noted at the inferio-lateral wound edge, where the RPI significantly decreased on day 1.

CONCLUSION

The distal part of the wound was significantly more hypoxic than the proximal part in minimal incision TKA. Atraumatic wound edge retraction should be carried out especially in the distal part. Although further investigation is necessary, delayed wound healing is potentially associated with regional skin hypoxia on day 1.

Temperature preference during forelimb regeneration in the red-spotted newt Notophthalmus viridescens

Red-spotted newts (Notophthalmus viridescens) are model organisms for regenerative research. These animals can regenerate limbs, tails, jaws, spinal cords, as well as the lens of the eye. Newts are small ectotherms that are aquatic as adults; as ectotherms, they naturally conform to the temperature of their surroundings. Environmental temperatures, however, can increase or decrease the red-spotted newt's metabolic processes, including their rate of tissue regeneration; whether an optimal temperature for this rate of regeneration exists is unknown. However, newts do exhibit behavioral preferences for certain temperatures, and these thermal preferences can change with season or with acclimation. Given this flexibility in behavioral thermoregulation, we hypothesized that the process of tissue regeneration could also affect thermal preference, given the metabolic costs or altered temperature sensitivities of tissue regrowth. It was predicted that regenerating newts would select an environmental temperature that maximized the rate of regeneration, however, this prediction was not fully supported. Thermal preference trials revealed that newts consistently selected temperatures between 24 and 25°C throughout regeneration. This temperature selection was warmer than that of uninjured conspecifics, but was lower than temperatures that would have further augmented the rate of regeneration. Interestingly, regenerating newts maintained a more stable temperature preference than sham newts, suggesting that accuracy in thermoregulation may be more important to regenerating individuals, than to noninjured individuals.