Transcutaneous oxygen tension in the leg during exercise in patients with chronic cardiac failure

The transcutaneous partial pressure of oxygen measured in the lower limb was compared in 16 patients with chronic cardiac failure and seven normal subjects. At rest, there was no significant difference between patients and normals. At peak exercise, the partial pressure of oxygen fell significantly in those in heart failure, whereas no change was observed in normal subjects. No changes in arterial oxygen saturation (oximetry) were observed. These changes are likely to reflect abnormalities of peripheral perfusion of the skin.     

Transcutaneous oxygen saturation and carbon dioxide tension during meals in patients with chronic obstructive pulmonary disease

The effect on transcutaneous SaO2 and transcutaneous carbon dioxide tension (PtCO2) of eating was assessed in 44 patients with severe COPD (FEV1 less than 50 percent). The SaO2, PtCO2, and heart rate (HR) were measured every minute before, during, and until 30 minutes after a standardized meal (445 kcal) was consumed. All patients were measured twice on the same day, while eating a meal with high (80 percent) and low (28 percent) carbohydrate content, respectively. The mean meal desaturation (delta SaO2) was less than 1 percent in normoxemic patients but was -3.2 +/- 0.7 percent (p less than 0.001) in hypoxemic (PaO2 less than 7.3 kPa) patients. Significant differences between hypoxemic patients with a delta SaO2 greater than 4 percent and less than or equal to 4 percent, respectively, were found in FEV1 (16 +/- 3 percent and 29 +/- 8 percent; p less than 0.001), respiratory muscle strength (3.9 +/- 1.2 kPa and 5.9 +/- 1.2 kPa; p less than 0.01), HR (112 +/- 12 beats per minute and 90 +/- 18 beats per minute; p less than 0.001), body weight (54.9 +/- 7.5 kg and 74.7 +/- 10.4 kg; p less than 0.001), and fat-free mass (42.0 +/- 6.6 kg and 52.6 +/- 5.8 kg; p less than 0.005) but not in baseline SaO2 and PtCO2. The decrease in SaO2 and the increase in HR were less during the carbohydrate-rich meal. No significant fluctuations in PtCO2 were found after either meal. Meal-related oxygen desaturation cannot explain weight loss in normoxemic patients with COPD but may contribute to a limited dietary intake in a subgroup of hypoxemic patients exhibiting marked oxygen desaturation during meals. A single carbohydrate-rich meal does not have an immediate impact on PtCO2 in stable COPD.     

Transcutaneous oxygen tension in sick infants

The clinical usefulness of the transcutaneous O2 electrode was investigated in 30 sick infants; 159 simultaneous measurements of arterial PO2 and transcutaneous PO2 were made. During the comparisons, arterial blood pressure, heart rate, and thoracic impedance were continuously recorded, and skin axillary and environmental temperatures and hematocrit were noted. Despite a wide range of arterial blood pressure and hematocrits, arterial PO2 and transcutaneous PO2 were similar (slope, 0.963), except for 2 groups of sick infants. Some infants with severe, persistent pulmonary hypertension who were receiving an intravascular infusion of tolazoline and infants with mean arterial blood pressures more than 2.5 SD less than the predicted average had values for transcutaneous PO2 that were lower than PO2. The surface O2 electrode is safe and relatively easy to use and provides data that can help in the management of most sick infants.     

Local oxygen content in the skin is increased in chronic venous incompetence

In skin lesions of chronic venous incompetence (CVI) transcutaneous oxygen pressure (tcpO(2)) at the ankle is often reduced. However, in some CVI patients the tcpO(2) during suprasystolic occlusion remains significantly higher than in healthy subjects. The aim of the present study was to investigate which kind of CVI patients develop this phenomenon and whether the higher tcpO(2) during occlusion is caused by a smaller oxygen consumption of the skin or by an increased local oxygen content. The oxygen consumption of the skin was measured by the pO(2) decrease (DeltatcpO(2)/Deltat) after stopping the arterial oxygen supply when the hemoglobin was saturated by oxygen inhalation, i.e., at tcpO(2) values above 120-130 mmHg. By multiplying the tcpO(2) with the mean oxygen solubility coefficient of the skin the content of physically dissolved oxygen is obtained. The decrease of tcpO(2) in the 55- to 45-mmHg range indicates the consumption of oxygen physically dissolved and chemically bound to hemoglobin. It gave a parameter for estimating the local hemoglobin content of the skin. These values and the minimal tcpO(2) after a 5-min arterial occlusion were measured in 14 healthy subjects, in 13 patients with varicose veins, but no skin lesions, in 10 patients with CVI lesions like white atrophy and lipodermatosclerosis and in 16 CVI patients with open venous ulcers. During suprasystolic occlusion tcpO(2) at the ankle remained significantly higher in CVI patients with skin lesions than in the healthy control subjects (25.6 +/- 18.9 versus 8.0 +/- 7.0 mmHg). The steepness of the tcpO(2) decrease caused by cutaneous oxygen consumption in healthy subjects was not significantly different from the CVI patients. In contrast, the decrease of tcpO(2) at the ankle between 55 and 45 mmHg was 1.9 +/- 2.0 mmHg/s in the control group and 0.7 +/- 0.5 mmHg/s in the group with open venous ulcers. These results indicate a higher hemoglobin content in the skin of the CVI patients than in healthy subjects. Obviously, the hemoglobin bound oxygen content in the skin of CVI patients is increased. Thus, a lack of oxygen is unlikely to be the primary reason for the development of skin lesions in CVI.     

Transcutaneous oxygen tension measurements during methacholine challenge of prematurity in infants with chronic lung disease

Chronic lung disease (CLD) of prematurity may be caused by a number of insults during mechanical ventilation, including barotrauma and hyperoxia. To evaluate bronchial hyperresponsiveness (BHR) in infants with CLD of prematurity, we measured changes in transcutaneous oxygen tensions (tcPO₂) during methacholine inhalation challenge. Twelve infants with CLD and 22 age-matched children without respiratory diseases were enrolled in this study (ages—5 to 36 months; mean age—16.2 months). Serial doses of methacholine were doubled until a 10% decrease in tcPO₂ from baseline was reached. The cumulative dose of methacholine inhaled by the time tcPO₂ had been reached (Dmin-PO₂) was considered to represent the dose at which reactivity to methacholine (RO₂meth) had occurred. In the CLD group, Dmin-PO₂ (3.50 ± 0.1 log.milli-units) was significantly lower than in the preterm control infant group (4.31 ± 0.2 log·milli-units) and the term infant group (4.21 ± 0.1 log.milli-units) (P = 0.004, P < 0.001). Dmin-PO₂ in the preterm control infant group was not significantly different than in the term infant group (P > 0.5). These results suggest that infants who require additional therapeutic oxygen and mechanical ventilation during the early months of life are at risk of developing early-onset, long-lasting respiratory disease that is related to an acquired BHR. Pediatr Pulmonol. 1998; 25:338–342. © 1998 Wiley-Liss, Inc.     

Transcutaneous oxygen tension in patients with post-thrombotic leg ulcers: treatment with intermittent pneumatic compression

Transcutaneous oxygen tension (TcPO2) and the effect of intermittent pneumatic compression on tissue oxygenation were studied in 10 patients with post-thrombotic leg ulcers. Oxygen tension was measured near the edge of the leg ulcer before and after 60 min of intermittent compression at 50 mmHg. The control group consisted of nine subjects with no evidence of peripheral vascular disease. The mean TcPO2 for the controls was 59.7 (SEM2.9) mmHg and for the study group 26.2 (SEM7.0) mmHg before treatment and 42.7 (SEM6.4) mmHg after treatment (p less than 0.005). Oxygen tension increased in nine patients in the study group. The change in TcPO2 correlated highly significantly (r = 0.912, p less than 0.002) with the reduction of oedema and the inverse change of skin temperature. The results suggest that intermittent pneumatic compression decreases interstitial fluid volume and venous stasis, both of which may lead to increased tissue oxygenation.     

Transcutaneous oxygen tension in arms of women with unilateral postmastectomy lymphedema

Previous reports suggest that skin blood flow is reduced in arms of women with lymphedema due to breast cancer treatment. Since tissue oxygenation depends on blood flow, we sought to determine if transcutaneous oxygen tension (TcPO2) is also reduced and if so, if therapy that reduces edema has a beneficial effect. TcPO2 was measured in fibrotic areas of affected arms and in corresponding sites on non-affected arms of 15 women with unilateral arm lymphedema before and after CDP therapy sequences. Fibrosis was assessed by indentation recovery times (IRT) after applying an indenter-like device to tissue. Volumes and edema percentages were determined from circumferences using automated software calculations. Treatment significantly (p < 0.01) reduced arm edema from 28.6 +/- 22.9% to 18.1 +/- 17.7% (mean +/- SD) and fibrotic segment edema from 42.6 +/- 30.1% to 25.0 +/- 20.4%, and softened fibrotic tissue judged by reductions in IRT (88.7 +/- 60.7 sec vs. 23.1 +/- 38.8 sec, p < 0.001). TcPO2 did not differ between arms initially and did not change with treatment, being 60.1 +/- 8.8 mmHg at the start and 61.8 +/- 9.2 mmHg at the end of treatment. Thus, despite significant amounts of initial edema, TcPO2 was not initially less in affected arms nor was it changed by therapy that improved both edema and fibrosis.     

Transcutaneous oxygen tension monitoring after successful revascularization in diabetic patients with ischaemic foot ulcers.

OBJECTIVE: To monitor transcutaneous oxygen tension (TcPO2) after percutaneous transluminal angioplasty (PTA) in diabetic patients with ischaemic foot ulcers. RESEARCH DESIGN AND METHODS: Twenty-three diabetic patients with ischaemic foot ulcers who underwent successful revascularization by PTA (SR group) were retrospectively selected. Twenty diabetic patients who underwent unsuccessful revascularization (UR group) were also included. Transcutaneous oxygen tension was measured at the dorsum of the foot before and 1 (+/- 1), 7 (+/- 1), 14 (+/- 1), 21 (+/- 1) and 28 (+/- 1) days after the surgical procedure. RESULTS: After PTA, TcPO2 progressively improved in the SR group, reaching its peak 4 weeks after angioplasty. A concomitant decrease of cutaneous carbon dioxide tension (TcPCO2) was also observed immediately after PTA which reached the lowest levels 3 weeks later. In the UR group, TcPO2 showed a slight improvement immediately after PTA but remained stable throughout the observation, while TcPCO2 levels did not change. Finally, the percentage of SR patients with a TcPO2 > or = 30 mmHg was 38.5% 1 week after PTA, while it increased to 75% 3 weeks later. CONCLUSION: Transcutaneous oxygen tension monitoring showed that after successful revascularization it takes 3-4 weeks for cutaneous oxygenation to improve and reach the optimal levels for wound healing. Transcutaneous carbon dioxide tension monitoring may be more useful to identify the negative outcome of a revascularization procedure. Our findings suggest that, when the surgical approach can be delayed, the best timing to perform a more aggressive debridement or minor amputations is 3-4 weeks after successful revascularization.     

Transcutaneous oxygen tension measurements during graded hemorrhage and reinfusion

Measurement of transcutaneous oxygen tension (PtCO2) has been suggested as a useful monitoring tool in the hypovolemic patient. Our study was undertaken to evaluate changes in PtCO2 that occur during graded hemorrhage and reinfusion, and to compare PtCO2 values to standard cardiorespiratory and biochemical parameters during hypovolemia. Seven mongrel dogs were bled 50% of their estimated blood volume (44 mL/kg) over one hour. This was followed by a one-hour monitoring period, a 30-minute reinfusion period, and an additional one-hour monitoring period. Pulmonary capillary wedge pressure (PCWP), central venous pressure (CVP), cardiac output (CO), mean arterial pressure (MAP), mixed venous oxygen tension (MvO2), arterial blood gases, and PtCO2 were measured serially throughout the study period. Cardiac index (CI), peripheral vascular resistance (PVR), O2 consumption, delivery, and percentage of extraction were calculated for each sampling period. A statistically significant fall in CI, MvO2 and PCWP occurred following the first 10% of blood loss; PtCO2 and MAP fell significantly after 20% hemorrhage; CVP fell after 30% hemorrhage. PtCO2 rose significantly after the first 10% of reinfusion, and it continued to rise during the entire reinfusion period, as did MvO2, CO, MAP, CVP, and PCWP. In contrast to the other measured variables, the elevations in PtCO2, and MvO2 were more pronounced early in the reinfusion period. During postreinfusion monitoring, PtCO2, MvO2, CO, and PCWP fell significantly despite maintenance of prehemorrhage MAP and CVP. Overall PtCO2 correlated well with MvO2 and the O2 extraction ratio, and to a lesser extent with CI, MAP, and O2 delivery.(ABSTRACT TRUNCATED AT 250 WORDS)     

Predictive values in the progression of chronic venous insufficiency associated with superficial venous incompetence

The purpose of this study was to define predictive values in the progression of chronic venous insufficiency in patients with isolated superficial venous incompetence using duplex ultrasound and air plethysmography (APG). Five hundred eight legs in 371 patients with isolated superficial venous incompetence were included in this study. A color duplex scanner with a 5- to 10-MHz linear transducer was used to assess the distribution and the extent of venous reflux as well as the duration of reflux and the retrograde peak velocity at the saphenofemoral junction, greater saphenous vein in the thigh, and the saphenopopliteal junction. Venous reflux was considered to be present if the duration of reflux was greater than 0.5 s. The extent of greater saphenous vein is divided into 3 types. Type I: reflux from the groin to the ankle. Type II: reflux from the groin to the below-knee level. Type III: reflux from the groin to the above-knee level. Values obtained by APG were the venous volume (VV), venous filling index (VFI), ejection fraction (EF), and residual venous fraction (RVF). Between-group differences were analyzed using Wilcoxon's nonparametric rank sum test. Type I limbs had highest incidence of advanced chronic venous symptoms. Based on the duplex-derived duration of reflux and retrograde peak velocity in Type I limbs, there were three major groups: limbs with a retrograde peak velocity greater than 30 cm/s and a duration of reflux less than 3 s (group A), limbs with a retrograde peak velocity greater than 30 cm/s and a duration of reflux greater than 3 s (group B) and limbs with a retrograde peak velocity of less than 30 cm/s and a duration of reflux greater than 3 s (group C). Most of the class 2 and class 3 limbs belonged to Group C, whereas most of the class 4 limbs and all of the class 5 and class 6 limbs belonged to group A and group B. APG-derived VFI had significantly higher values in group A and group B compared with group C (P<0.002). Peak velocity greater than 30 cm/s had a high positive predictive value of 75.0% with a sensitivity of 91.1%. Although duplex-derived duration of reflux is widely used to assess venous reflux, our data suggest that the peak velocity is a better predictor of the progression of chronic venous insufficiency and that it correlates well with the severity of the clinical manifestation in cases with isolated superficial venous insufficiency.Presented in part at the 41st Annual World Congress, International College of Angiology, Sapporo, Japan, July, 1999.     

Transcutaneous oxygen tension (TcPO2) measurement as a diagnostic tool in patients with peripheral vascular disease

Transcutaneous oxygen tension (TcPO2) was measured through Clark's electrode at the dorsum of the foot in 52 healthy controls whose ages ranged from twenty to sixty-five years (mean 45.05 +/- 14.09) and 36 nondiabetic patients with peripheral vascular disease (PVD) (5 stage I, 16 stage II, 4 stage III, 11 stage IV), under standardized conditions at rest and during recovery from limb ischemia obtained with pneumatic cuff compression for 3 minutes. At rest the TcPO2 averaged 71.20 +/- 14.26 mm Hg (range 46-92) in the controls and 51.56 +/- 26.38 in the PVD patients (p less than .01). A wide overlap was observed between the two groups and among the different stages of the disease, and consequently, the diagnostic value of TcPO2 at rest was limited (sensitivity equal to 32%). During the recovery from ischemia the time constant (recovery half-time, T1/2) averaged 38.01 +/- 7.23 sec in the controls and 55.84 +/- 19.82 in the PVD patients (p less than .01). The T1/2 added to the diagnostic value of the method, making it more sensitive (55%), especially for stage II patients. The TcPO2 at rest was lower with increasing severity of the disease; both the TcPO2 at rest and the T1/2 correlated with the ankle-arm pressure index in the diseased limbs (r = .48 and -.41 respectively, p less than .001).(ABSTRACT TRUNCATED AT 250 WORDS)     

腭裂术后VPI患者的辅音发声特点

目的观察腭裂术后腭咽闭合不全（VPI）患者的辅音发声特点。方法腭裂术后VPI患者56例（VPI组,年龄5～18岁）,手术史〉3 a且没有进行语音训练;健康儿童20例（对照组,年龄5～16岁）。分析两组辅音[b]、[d]、[g]、[z]、[x]的充值条和擦音乱纹出现率,以及语句中[ti]的嗓音起声时间（VOT）和[ma]、[ba]的过渡音征。结果 VPI组辅音冲直条和擦音乱纹出现率显著低于对照组（P均〈0.05）;VPI组的VOT接近零甚至成为负值,与对照组相比,P〈0.01;两组[ba]的正渡率差异显著（P〈0.05）。结论腭裂术后VPI患者的辅音发声特点为辅音脱落或弱化、清辅音浊化、口辅音鼻化等。     

Relationship between mixed venous oxygen saturation and cardiac index in patients with chronic congestive heart failure

The use of mixed venous oxygen saturation (SvO2) in patients with chronic congestive heart failure (CHF) has been advocated to analyze the action of therapy on cardiac index (CI). To evaluate the relationship between CI and SvO2, ten CHF patients (mean age 65 years) were studied before and one, two, three, four (T4), six, eight and 24 hours after oral administration of an angiotensin converting enzyme (ACE) inhibitor (perindopril, 4 mg). At T4, a 12 percent increase in CI (p less than 0.01) was associated with a 16 percent decrease in arteriovenous oxygen difference (p less than 0.01), a 13 percent increase in mixed venous oxygen pressure (PvO2) (p less than 0.01), and a 9 percent increase in SvO2 (p less than 0.05) with no significant change in arterial oxygen pressure. There was no correlation between CI and SvO2 (r = 0.22) and between CI and PvO2 (r = 0.23). Individual analyses were performed and patients were divided into two groups based on CI versus SvO2 r value; group 1, n = 6, r greater than 0.65 (0.65-0.90), group 2, n = 4, r less than 0.65 (0.14-0.20). The lack of correlation in group 2 was due to a drug-dependent increase in oxygen consumption (VO2) +18 percent vs -3 percent in group 1 (p less than 0.05) associated with a lack of increase in PvO2 +3 percent vs +14 percent in group 1 (p less than 0.05) despite a similar increase in oxygen availability +19 percent versus +16 percent. It was concluded that (1) a correlation between CI and SvO2 is not found in every patient with CHF; (2) the lack of correlation in four out of our ten patients was due to an associated and significant increase in CI and VO2 in group 2; (3) group 2 patients probably had an important oxygen debt before treatment; (4) SvO2 cannot be used instead of CI to determine the hemodynamic consequences of the use of cardiovascular drugs.     

Effect of nasogastric feedings on arterial oxygen tension in patients with symptomatic chronic obstructive pulmonary disease

Meal-induced hypoxemia may occur in asymptomatic patients with chronic obstructive pulmonary disease (COPD). The need to address the nutritional requirements in symptomatic COPD patients has recently been reported. Accordingly, we studied the effect of nasogastric feedings on arterial oxygen tension in patients receiving nasogastric feedings. Eleven patients studied had heterogeneous symptomatic COPD with various requirements for either bronchodilators, oxygen, or ventilator support. Samples for arterial blood gas (ABG) determinations were drawn (first ABG value) at the time of interrupting continuous feedings (75 ml/hr) or just before a small bolus feeding (75 ml). A repeat ABG sample (second ABG value) was drawn 30 minutes later. There was a small but statistically significant difference between the first and second arterial oxygen tension values. This difference, however, was not clinically significant. Our preliminary results suggest that symptomatic COPD patients experience hypoxemia with nasogastric feedings.