Transcutaneous Partial Oxygen Tension Research Articles

Developing a Practical Tool for Predicting Wound Healing Outcomes of Patients with Diabetic Forefoot Ulcers: Focus on Vasculopathy and Infection.

To develop a preliminary risk scoring system to predict the prognosis of patients with diabetic forefoot ulcers based on the severity of vasculopathy and infection, which are the major risk factors for amputation. Forefoot was defined as the distal part of the foot composed of the metatarsal bones and phalanges and associated soft tissue structures. The degree of vasculopathy was graded as V0, V1, or V2 according to transcutaneous partial oxygen tension values and toe pressure. The degree of infection was graded as I0, I1, or I2 according to tissue and bone biopsy culture results. The risk scores were calculated by adding the scores for the degree of vasculopathy and infection and ranged from 0 to 4. Wound healing outcomes were graded as healed without amputation, minor amputation, or major amputation. The authors evaluated wound healing outcomes according to risk scores. As the risk score increased, the proportion of patients who underwent both major and minor amputations increased (P < .001). In the multivariate logistic analysis, the odds ratios of amputation also increased as the risk score increased. Patients with a risk score of 4 were 75- and 19-fold more likely to undergo major and minor amputations, respectively, than patients with a risk score of 0 (P = .006 and P < .001). The risk score can be used as an indicator to predict the probability of amputation in patients with diabetic forefoot ulcers.

Can macrocirculation changes predict nonhealing diabetic foot ulcers?

Transcutaneous partial oxygen tension (TcpO2) is considered the gold standard for assessment of tissue oxygenation, which is an essential factor for wound healing. The purpose of this study was to evaluate the association between macrocirculation and TcpO2 in persons with diabetes mellitus. Ninety-eight patients with diabetic foot ulcers participated in the study (61 men and 37 women). The subjects had a mean age of 66.6 years (range, 30-83 years) and were treated at the Diabetic Wound Center of Korea University Guro Hospital, Seoul, Republic of Korea. Macrocirculation was evaluated using 2 techniques: computed tomographic angiography and Doppler ultrasound. Macrocirculation scores were based on the patency of the two tibial arteries in 98 patients. Computed tomographic angiography and Doppler ultrasound scores (0-4 points) were given according to intraluminal filling defects and arterial pulse waveform of each vessel, respectively. Tissue oxygenation was measured by TcpO2. Macrocirculation scores were statistically analyzed as a function of the TcpO2. Statistical analysis revealed no significant linear trend between the macrocirculation status and TcpO2. Biavariate analysis using the Fisher exact test, Mantel-Haenszel tests, and McNemar-Bowker tests also found no significant relationship between macrocirculation and TcpO2. Computed tomographic angiography and Doppler ultrasound are not sufficiently reliable substitutes for TcpO2 measurements in regard to determining the optimal treatment for diabetic patients.

Effect of normobaric hyperoxic therapy on tissue oxygenation in diabetic feet: A pilot study

Adequate tissue oxygenation is an essential factor in diabetic foot management. Hyperbaric oxygen (HBO) therapy has been successfully used as adjunctive treatment to improve the healing of diabetic foot ulcers. However, the clinical uses of HBO therapy are limited due to the low availability of HBO chambers, poor patient compliance, and high oxidative potential. Normobaric hyperoxic (NBO) therapy may be a potentially attractive alternative to HBO therapy because of its high availability, good patient compliance, and few technical requirements. Several studies on NBO therapy to attenuate infarct volume after stroke have provided compelling evidence. However, there have been no reports regarding the effect of NBO therapy in the field of wound healing. The purpose of this study was to evaluate the effect of NBO therapy on tissue oxygenation of diabetic feet. This study included 100 patients with diabetic foot ulcers (64 males and 36 females). Transcutaneous partial oxygen tension (TcPO₂) values of diabetic feet were measured before, during, and after NBO therapy. The mean TcPO₂ values before, during, and after therapy were 46.6 ± 21.5, 88.9 ± 48.0, and 49.9 ± 23.8 mmHg (p < 0.001), respectively. The lower the initial TcPO₂ level, the more TcPO₂ increased. The results reveal that NBO therapy significantly increases the tissue oxygenation level of diabetic feet.

Is the foot elevation the optimal position for wound healing of a diabetic foot?

In managing diabetic foot ulcers, foot elevation has generally been recommended to reduce oedema and prevent other sequential problems. However, foot elevation may decrease tissue oxygenation of the foot more than the dependent position since the dependent position is known to increase blood flow within the arterial system. In addition, diabetic foot ulcers, which have peripheral vascular insufficiency, generally have less oedema than other wounds. Therefore, we argue that foot elevation may not be helpful for healing of vascularly compromised diabetic foot ulcers since adequate tissue oxygenation is an essential factor in diabetic wound healing. The purpose of this study was to evaluate the influence of foot height on tissue oxygenation and to determine the optimal foot position to accelerate wound healing of diabetic foot ulcers. This study included 122 cases (73 males and 47 females; two males had bilateral disease) of diabetic foot ulcer patients aged 40-93 years. Trans-cutaneous partial oxygen tension (TcpO(2)) values of diabetic feet were measured before and after foot elevation (n=21). Elevation was achieved by placing a foot over four cushions. We also measured foot TcpO(2) values before and after lowering the feet (n=122). Feet were lowered to the patient's tibial height, approximately 30-35 cm, beside a bed handrail. Due to the large number of lowering measurements, we divided them into five sub-groups according to initial TcpO(2.) Tissue oxygenation values were compared. Foot-elevation-lowered TcpO(2) values before and after elevation were 32.5+/-22.2 and 23.8+/-23.1 mmHg (p<0.01), respectively. Foot-lowering-augmented TcpO(2) values before and after lowering were 44.6+/-23.8 and 58.0+/-25.9 mmHg (p<0.01), respectively. The lower the initial TcpO(2) level, the more the TcpO(2) level increased. The foot lowering, rather than elevation, significantly augments TcpO(2) and may stimulate healing of diabetic foot ulcers.

The Role of Hemodynamic Measurements in the Management of Venous and Ischemic Ulcers

There is a need for quantitative investigations in the vascular laboratory to manage lower extremity ulcers. The majority of leg ulcers are of venous (45%-60%) or arterial origin (10%-20%). Despite the increasing complexity of new devices used in vascular surgical practice, the anklebrachial pressure index (ABPI) remains the cornerstone for the differential diagnosis of ischemic ulcers. The toe-brachial pressure index and the pole test represent attractive alternative tests especially in patients with diabetes. Color flow Doppler imaging (CFDI) is advantageous over ABPI in cases in which wounds and ulcers prevent the use of a cuff by virtue of their size or location; additionally CFDI technology can detect nonflow limiting lesions, lesions to nonaxial arteries such as the deep femoral artery, or lesions limited to a single tibial artery. Continued improvements in the accuracy of CFDI have prompted some vascular surgeons to replace contrast arteriography in distal bypass procedures. Transcutaneous partial oxygen tension measurement (TcPO(2)) is another noninvasive method that is reliable to select the level of amputation and recommended to determine tissue viability in critically ischemic limbs and in the management of the diabetic foot. CFDI has revolutionized the diagnostic approach to venous disorders and it is considered the gold standard for the assessment of the venous system of the lower limb, causes minimal inconvenience to patients, and is easily repeatable, but it is considered highly operator dependent. Various plethysmography techniques are of limited application in ulcer investigations, because of their difficulty to calibrate signal, unless time measurements such as the postexercise refilling time are used.

Comparison of the effects of combined nicotine replacement therapy vs. cigarette smoking in males

This open study assessed the effects of nicotine replacement therapy (NRT) on the normalizing of exhaled carbon monoxide (CO), transcutaneous partial oxygen tension (tcpO 2 ), plasma cotinine and thiocyanate levels, and cardiovascular risk markers in abstinent subjects compared with untreated smokers after 4, 8, 12, and 26 weeks. The trial enrolled 197 subjects in two parallel groups: 164 subjects who received NRT (patch plus gum) for 12 weeks and 33 untreated smokers (controls). At 26 weeks, 123/164 participants in the treatment group had completed the study; 51/123 (41.5%) sustained abstinence from smoking, whereas 72/123 (58.5%) had relapsed. Changes in cotinine (abstainers: 291.6 ng/ml at baseline vs. 27.3 ng/ml at week 26; p<.0001) and thiocyanate levels (abstainers: 10.4 ng/ml at baseline vs. 6.2 ng/ml at week 26; p<.0001) and expired CO (abstainers: 30.4 ppm at baseline vs. 4.2 ppm at week 26; p<.0001) accurately reflected the changes in smoking and/or NRT use in both abstainers and relapsers. After they stopping smoking, tcpO2 significantly improved in abstainers (34.9 mmHg at baseline vs. 50.4 mmHg at week 26; p<0.0001). Inverse correlations between the number of daily cigarettes and plasma cotinine, thiocyanate, and exhaled CO levels were observed in both relapsers and smokers. A clinically significant increase in HDL cholesterol (39.0 vs. 44.7 mg/dl; p<.0001) occurred in the abstainers between baseline and study end. Use of combination NRT to achieve abstinence resulted in marked improvements in biochemical parameters in abstainers and partial improvements in relapsers. The safety of combination NRT was confirmed by the absence of overdose-related adverse events.

The role of microcirculatory techniques in patients with diabetic foot syndrome.

Diabetic foot syndrome (DFS) is a frequent complication of long-standing diabetes mellitus, occurring in 10 to 30 percent of all diabetics with a vital risk for the affected limb and high mortality rates. Macroangiopathy, diabetic polyneuropathy and infections are trigger factors for DFS. Recent results imply a pathogenic role of functional and structural microcirculatory changes. The exact role of microangiopathy and the value of microcirculatory diagnostic methods in DFS have not yet been defined. 78 patients with DFS (28 type I, 50 type II diabetics, mean age 63 years) were evaluated with video capillary microscopy, transcutaneous partial oxygen tension (tcpO2) measurement and laser Doppler fluxmetry (LDF) at the forefoot of the affected leg at admission and after revascularisation. Mean hospital stay was 28 +/- 11.7 days. Patients were stratified according to the etiology of DFS in patients with neuropathic lesions, macroangiopathic ulcers and mixed neuropathic-angiopathic lesions. All groups had impaired microcirculation, and significant differences between groups were found in respect to capillary density. Reactive hyperemia, LDF pattern and tcpO2 did not differ significantly. Microcirculatory examinations did not yield additional information to clinical and Doppler sonographic results. In clinical practice, the role of microcirculation evaluation techniques for diabetic foot syndrome is limited.

Transcutaneous Partial Oxygen Tension and Lung Mechanics During Methacholine Inhaled Challenge

Transcutaneous Partial Oxygen Tension and Lung Mechanics During Methacholine Inhaled Challenge

Transcutaneous partial oxygen tension and skin blood flow monitoring: Continuous, noninvasive measures of cardiorespiratory change

Transcutaneous partial oxygen tension (tc pO 2) and skin blood flow (via heat clearance) were measured noninvasively in 22 male subjects who performed stress-inducing tasks (i.e. hand-grip exercise, cold pressor test, breath holding, hyperventilation and mirror-tracing). An analysis of variance and covariance was conducted for tc pO 2 heat clearance, heart rate, respiration rate, finger pulse volume and systolic/diastolic blood pressure. Results indicate that tc pO 2 can depict phasic cardiorespiratory challenge. Heat clearance proved to be less sensitive to the demand conditions used here. An analysis of covariance revealed a negative correlation between tc pO 2 and blood pressure and respiration rate, as well as a positive correlation between tc pO 2 and heat clearance. This suggests that phasic changes in tc pO 2 are induced by both peripheral vasomotor activity and changes in arterial pO 2.

Catecholamines in arterial and venous umbilical blood: placental extraction, correlation with fetal hypoxia, and transcutaneous partial oxygen tension.

In 34 parturient women the levels of free epinephrine (E), norepinephrine (NE), and dopamine (D) were determined by a radioenzymatic method using maternal venous and umbilical arterial and venous blood. The study was conducted to investigate the relationship between fetal catecholamines and hypoxia, fetal heart rate (FHR), and transcutaneous pO2 (tcpO2). The placental catecholamine extraction rates were also calculated. Results The NE concentrations (10,200 pg/ml) and the E concentrations (1,120 pg/ml) in the fetal arterial blood were highly elevated with mean values increased 4-fold over umbilical vein values. Compared with the maternal venous blood, NE values were increased 20-fold, and E values 10-fold. Free D concentrations in fetal arterial blood (130 pg/ml) had risen 2.5-fold over maternal levels. These results suggest that the catecholamines measured in cord blood are of fetal origin and that the placenta has a high capacity for inactivation of free catecholamines. The placental extraction rate is 77 +/- 14% for NE, 76 +/- 16% for E, and 33 +/- 25% for D. The placental extraction rates for E and NE were virtually identical; in agreement with morphological studies they demonstrated absence of sympathetic innervation on the fetal side of the placenta. Highly significant correlations were found between fetal arterial NE concentrations and the 1-minute APGAR score, pH and base deficit in the umbilical artery and alterations of the FHR (deceleration area, baseline FHR). Further analysis of FHR alterations reveals that an increase in deceleration area without tachycardia is not correlated with an increase of fetal arterial NE concentration. A significant rise in NE was only found with additional tachycardia which is often associated with a loss of oscillation amplitude. Fetal arterial E concentrations were found to correlate with the fetal parameters indicating increased adrenal secretion of the hormone during fetal stress. However, correlation coefficients were lower than those obtained for NE. A significant effect of fetal hypoxia on arterial and venous D levels could not be demonstrated. Fetal tcpO2 varies between 0-25 mm Hg during the last two hours before delivery. In most cases tcpO2 was lower than the arterial pO2. Besides epidermal thickness and artifacts, skin perfusion is a major factor influencing the tcpO2 (transcutaneous arterial pO2 difference). Vasoconstriction of the cutaneous vessels induced by increased NE secretion during hypoxia may obviously produce a fall in tcpO2.(ABSTRACT TRUNCATED AT 400 WORDS)