Wound Oxygen Tension Research Articles

Impact of obesity on surgical site infection in colon and rectal surgery.

Obesity affects over 30% of the United States population. Over the past 10 years, there has been increased recognition of the prevalence of obesity and its contribution to worse outcomes among medical and surgical patients. In particular, obesity has been validated as a risk factor for surgical site infection (SSI) among patients undergoing major abdominal surgery with some reports demonstrating an increased risk of SSI as high as sixty percent (60%) among obese patients. For patients undergoing elective colon and rectal surgery, a higher incidence of SSI (up to 45%) has been reported in comparison to outcomes of other surgical procedures. Obesity, as well as numerous other variables, have been implicated as a potential source for this increased incidence. Although the pathophysiology of obesity-related SSI has been suggested (decreased wound oxygen tension, impaired tissue antibiotic penetration, altered immune function, etc.), the true effect of obesity has not been clearly described. The purpose of this review is to examine the growing epidemic of obesity and its specific impact on SSI for both general and colorectal surgical patients. The proposed mechanisms for why obesity increases the risk of SSI will be briefly discussed, as well.

Perioperative oxygen fraction – effect on surgical site infection and pulmonary complications after abdominal surgery: a randomized clinical trial. Rationale and design of the PROXI-Trial

BackgroundA high perioperative inspiratory oxygen fraction may reduce the risk of surgical site infections, as bacterial eradication by neutrophils depends on wound oxygen tension. Two trials have shown that a high perioperative inspiratory oxygen fraction (FiO2 = 0.80) significantly reduced risk of surgical site infections after elective colorectal surgery, but a third trial was stopped early because the frequency of surgical site infections was more than doubled in the group receiving FiO2 = 0.80. It has not been settled if a high inspiratory oxygen fraction increases the risk of pulmonary complications, such as atelectasis, pneumonia and respiratory failure. The aim of our trial is to assess the potential benefits and harms of a high perioperative oxygen fraction in patients undergoing abdominal surgery.Methods and designThe PROXI-Trial is a randomized, patient- and assessor blinded trial of perioperative supplemental oxygen in 1400 patients undergoing acute or elective laparotomy in 14 Danish hospitals. Patients are randomized to receive either 80% oxygen (FiO2 = 0.80) or 30% oxygen (FiO2 = 0.30) during surgery and for the first 2 postoperative hours. The primary outcome is surgical site infection within 14 days. The secondary outcomes are: atelectasis, pneumonia, respiratory failure, re-operation, mortality, duration of postoperative hospitalization, and admission to intensive care unit. The sample size allows detection of a 33% relative risk reduction in the primary outcome with 80% power.DiscussionThis trial assesses benefits and harms of a high inspiratory oxygen fraction, and the trial may be generalizable to a general surgical population undergoing laparotomy.Trial registrationClinicalTrials.gov identifier: NCT00364741.

Measuring Oxygen in Wounds

Publisher Summary The most important and commonly used methods for oxygen measurement, range from microelectrode measurements of wound oxygen gradients to clinically useful measurements in humans. Studies of the role of oxygen in wound healing turn on the ability to measure oxygen: in cell and tissue culture, in animal models, and in human wounds. The development of methods for the accurate measurement of wound oxygen tension has led to studies demonstrating that activation of the sympathetic nervous system by such common perioperative stressors as hypothermia, pain, and hypovolemia decreases wound oxygen tension and impairs wound healing. Tissue oxygen measurements are relatively simple to make, particularly with current highly stable probes. Concepts related to subcutaneous wound tissue oximetry and measurement of transcutaneous oxygen in patients with ulcers of the lower extremity are also discussed.

Development of subcutaneous wound oxygen measurement in humans: contributions of Thomas K Hunt, MD.

When, in the early 1960s, Thomas K. Hunt, MD began investigating the role of oxygen in wound healing, he recognized that translation to humans would require the ability to measure oxygen tension in human wounds. This article will review his contributions to the development of subcutaneous tissue oxygen measurement and to the understanding of wound physiology and oxygen delivery, particularly through use of oxygen measurement. Hunt's major contributions to the field include the observations that all wounds show some degree of hypoxia, while many are severely hypoxic; the degree of hypoxia in wounds is sufficient to impair wound healing, and particularly bacterial killing by neutrophils, collagen deposition, angiogenesis, and epithelization; the sympathetic nervous system plays a central role in decreasing wound oxygen supply; and wound oxygen delivery and wound healing capacity can be increased by controlling the sympathetic nervous system. All these observations required tissue oxygen measurement, and, in particular, translation of basic scientific observations to clinical research required a method of measuring wound oxygen tension in humans.

Pain Significantly Influences Postoperative Wound Oxygen Tension

Pain Significantly Influences Postoperative Wound Oxygen Tension

Oxygen Tension on the Surface of Suction Blister Wounds Measured with a Polarographic Technique in Healthy Volunteers

A polarographic oxygen electrode, operated at a temperature close to that of the local tissue, was used to measure oxygen tension in blister wounds in healthy volunteers (n: 18). The coefficient of variation (CV) in repeated assessments in single wounds on the lower leg varied between 7.8% and 15%. When deter mined in different volunteers, wound oxygen tension (PO2) was 8.9±2.0 kilopas cals (kPa) (mean±SD) (CV: 22.7%) on the day of infliction and 7.2±1.4 kPa (CV: 20.0%) on day 1. The oxygen values decreased gradually as healing pro ceeded. It was not established at which stage the reformed epidermis constituted an impediment to oxygen passage from the wound to the electrode, and to avoid this factor it would seem prudent to restrict measuring of wound PO2 to the first two to three days. The wound PO2 values were proportional to the oxygen pres sure of air inhaled at 101 kPa and 283 kPa. In forearm wounds, values de creased to zero kPa during brachial arterial occlusion. The oxygen values did not increase beyond the preocclusion level following the release of occlusive pressure. Repeated injections of increasingly concentrated noradrenalin into the blister wound resulted in a decrease in PO2 followed at higher concentrations by an increase. The findings indicate that the technique may be useful for as sessing oxygen supply to blister wounds.

Tissue Oxygenation, Anemia, and Perfusion in Relation to Wound Healing in Surgical Patients

Oxygen tension and collagen deposition were measured in standardized, subcutaneous wounds in 33 postoperative surgical patients. Pertinent clinical and wound parameters were analyzed by Pearson's correlation test and sequential linear regression analysis. Collagen deposition was directly and significantly proportional to wound oxygen tension and measures of perfusion. There were no significant correlations with hematocrit, estimated blood loss, length of operation, smoking, age, weight, sex, or urine output. This study in humans confirms animal experiments showing that collagen deposition and tensile strength in wounds are limited by perfusion and tissue oxygen tension. It appears unnecessary to maintain hemoglobin at normal levels to support repair, provided that peripheral perfusion can be maintained at a high level in compensation for anemia. These circumstances reflect the fact that although oxygen is essential to many aspects of healing, and must be delivered at adequate partial pressures, reparative tissue consumes relatively little of it.

Pyoderma Gangrenosum

Four patients with pyoderma gangrenosum were treated with hyperbaric oxygen to prepare the wounds for skin grafting. Each wound responded to a course of daily hyperbaric oxygen with reduction of infection and increased capillary angiogenesis. During follow-up periods of 12 to 30 months, all wounds remained healed. Although the exact etiology of pyoderma gangrenosum is unknown, vasculitis with wound ischemia and infection are prominent components. Inspired oxygen partial pressures of 1100 to 1300 mmHg elevate wound oxygen tension despite relative ischemia. The impaired intracellular bacterial killing of hypoxic leukocytes is corrected during each day's 2-hour bolus of hyperbaric oxygen. Daily wound oxygenation increases collagen production by fibroblasts to support capillary angiogenesis.

Wound oxygen tension of large vs. small wounds in man

Wound oxygen tension of large vs. small wounds in man

Oxygen supply in healing tissue

Three different methods were used for measuring the oxygen tension in healing tissue. Average extracellular wound oxygen tension and its response to systemic hyperoxia and hypoxia were recorded in rats by using perfused Teflon tonometer coils 50 cm long within cylindrical sponge granulomas implanted subcutaneously. Dead space pO 2 and its variations with changing ambient pO 2 were determined. In the second method, intercapillary oxygen gradients and tissue oxygen tensions in various parts of the connective tissue capsule surrounding subcutaneous sponge implants were determined with ultramicro oxygen electrodes under visual control. The effects of oxygen breathing on tissue oxygen gradients were also recorded. In the third part of the study measurements were made with ultra-micro electrodes of the oxygen microclimate during healing in rabbit ear chambers. The dead space pO 2 varied between 0 and 3 mm Hg. Fibroblast proliferation appeared to be greatest in the zone where pO 2 was between 20 and 30 mm Hg. Collagen accumulation appeared in a region of slightly higher oxygen tension. The growing edge of granulation tissue contained cells similar to macrophages and the pO 2 in this zone was 5 to 15 mm Hg. Breathing of pure oxygen greatly increased the intercapillary oxygen gradients in the vicinity of the advancing capillary arcade. Measurements during exposure to oxygen suggest that the demand for oxygen in the area of collagen formation is less than that in the zone of active fibroblast proliferation.