Transcutaneous carbon dioxide tension for the evaluation of limb ischemia

Purpose  Understanding the hemodynamics of critical limb ischemia caused by chronic peripheral arterial occlusive disease is important to evaluate its severity and the efficacy of treatment. We investigated the usefulness of transcutaneous carbon dioxide tension (tcPCO₂) measurement for evaluating ischemic limbs, in conjunction with the measurement of ankle pressure (AP), toe pressure (TP), skin perfusion pressure (SPP), and transcutaneous oxygen tension (tcPO₂). Methods  We measured tcPCO₂ in the dorsum of the foot in 158 patients (304 limbs) with arteriosclerosis obliterans. Results  The tcPCO₂ in normal limbs without any clinical sign or abnormal noninvasive measurement was 43.7 ± 3.7 mmHg; that in noncritical ischemic limbs was 45.5 ± 9.0 mmHg, which was not significantly different from that in the normal limbs; and that in critically ischemic limbs was 87.6 ± 35.5 mmHg, which was significantly different from that in the normal limbs. All limbs with a tcPCO₂ of 100 mmHg or higher, indicative of critical ischemia, had a tcPCO₂ of less than 100 mmHg after revascularization. Conclusion  We found tcPCO₂ to be a useful measurement for diagnosing the severity of limb ischemia, and for evaluating the effect of treatment, especially in patients with critically ischemic limbs.     

Effects of the electrode temperature of a new monitor, TCM4, on the measurement of transcutaneous oxygen and carbon dioxide tension

The transcutaneous measurement of oxygen (tcP_{O 2}) and carbon dioxide (tcP_{CO 2}) tensions may serve as a surrogate of arterial oxygen (Pa_O2) and carbon dioxide (Pa_{CO 2}) tensions, respectively. We investigated the effects of the electrode temperature of a new device, TCM4, on the measurement of tcP_{O 2} and tcP_{CO 2}. Twenty-five patients scheduled for major lower abdominal surgery were enrolled. The electrode of the TCM4 was attached to the chest, with its temperature set to 37°C, 40°C, 42°C, 43°C, or 44°C. tcP_{O 2}, tcP_{CO 2}, end-tidal carbon dioxide tension (Et_{CO 2}), Pa_{O 2}, and Pa_{CO 2} were simultaneously measured at various Et_{CO 2} levels and inhaled oxygen concentrations. The times required for stabilization of the tcP_{O 2} and tcP_{CO 2} values were measured. A Bland-Altman plot was used to compare the two measurements. The time required for stabilization was shorter with a higher electrode temperature, but the shortest time was still more than 150 s. TcP_{O 2} correlated well with Pa_{O 2} at 43°C and 44°C. TcP_{CO 2} correlated well with Pa_{CO 2} and Et_{CO 2} at 43°C. The bias and limits of agreement were larger with lower electrode temperature for TcP_{O 2}—Pa_{O 2}, tcP_{CO 2}—Pa_{CO 2}, and tcP_{CO 2}—Et_{CO 2}. We concluded that the electrode of the TCM4 should be heated to at least 43°C to measure tcP_{O 2} and tcP_{CO 2}. However, the absolute values of tcP_{O 2} and tcP_{CO 2} could not be used as surrogate measurements of Pa_{O 2} and Pa_{CO 2}, respectively.     

The Usefulness of Transcutaneous Oximetry in Assessing the Success of Percutaneous Transluminal Angioplasty

OBJECTIVE: to identify whether monitoring transcutaneous oxygen pressure (TcpO(2)) can provide an objective method of assessing the results of PTA. MATERIALS AND METHODS: fifty-seven patients (39 Fontaine stage II, <18 stage III or IV) had ABI, TcpO(2) at rest (stages III and IV) or during exercise (stage II) and total work capacity of the leg (stage II) measured before, 24-48 h, 2 and 6 weeks after PTA. RESULTS: a significant increase of ABI in both groups of patients was detected immediately after successful PTA. TcpO(2) measured on the foot at rest increased in stages III and IV patients immediately after PTA (from 14 (IQR)18 to 25 (IQR)32 mmHg,p <0.05) and again after 6 weeks in comparison to follow up two (from 25 (IQR)32 to 35 (IQR)21 mmHg,p <0.05). In patients in stage II TcpO(2) decreased in a typical fashion during exercise. Total oxygen drop was most evident before treatment (352 (IQR)458 smmHg) and decreased significantly immediately after PTA (148 (IQR)175 smmHg, p<0.001). CONCLUSIONS: TcpO(2) measurement is an useful method for investigating the success of PTA. While the macrocirculation improves immediately after successful recanalisation, complete normalisation of the microcirculation may take some weeks, especially stages III and IV disease.     

Oxygen Tension Monitoring in Uremic Patients During Hemodialysis Treatment

The aim of this study was to evaluate the influence on cerebral and cutaneous vascular regions of PaO2 reduction during acetate dialysis, by monitoring conjunctival oxygen tension (PcjO2) and transcutaneous oxygen tension (PtcO2) during hemodialysis (HD) treatment. The study was performed on 23 patients with end-stage renal disease in chronic HD. All patients underwent dialytic treatment with cuprophan membranes and acetate containing dialysate. PcjO2 and PtcO2 were recorded and PaO2 and arterial carbon dioxide tension (PaCO2) were also measured. Results of the study show that hypoxemia during acetate dialysis with cuprophan membranes is not accompanied by changes of PcjO2 and therefore by changes in cerebral oxygenation. Moreover, PtcO2 remains constant during dialysis treatment. Furthermore, maintenance of normal oxygen tension at the conjunctival level is not obtained at the expense of the peripheral region of the skin.     

Intraoperative transcutaneous oxygen tension criteria for completion arteriography

During the past three years, we studied the value of transcutaneous oxygen monitoring in 28 lower extremity vascular bypass procedures. In 21 reconstructions, a rapid rise in the transcutaneous oxygen tension following reperfusion was indicative of a patent graft and patent runoff vessels. Inadequate revascularization was identified in three of four patients in whom transcutaneous oxygen tension failed to rise following femorodistal arterial bypass (positive predictive value 75%). A normal intraoperative transcutaneous oxygen tension study following femorodistal bypass had a negative predictive value of 95%. The overall accuracy was 91%. Transcutaneous oxygen tension monitoring during lower extremity vascular bypass procedures is useful in assessing the success of revascularization and may be used to select which patients should undergo completion arteriography as opposed to those in whom an arteriogram is not essential.     

Transcutaneous CO2 tension measurement as an indicator of severity of hemorrhagic shock

This study was undertaken to evaluate whether transcutaneous CO₂ tension (PtcCO₂) could be used as an indicator of the global systemic severity of hemorrhagic shock. PtcCO₂ levels in ten anesthetized mongrel dogs were measured during hemorrhage and during volume restoration and were correlated with mixed venous CO₂ tension ( ). After withdrawal of 30ml·kg⁻¹ blood, both PtcCO₂ and increased significantly (from 43±7 to 70±27 torr (P<0.05) and from 48±6 to 59±12 torr (P<0.05), respectively). Throughout the experiments, PtcCO₂ levels changed almost in parallel to levels. However, changes in PtcCO₂ exceeded those in from the end of hemorrhage, at which time cardiac output decreased to 35% of the baseline value, until the end of volume restoration, and the changes in PtcCO₂ showed a close logarithmic relationship with (r=0.78,n=110). Additionally, arterio-transcutaneous CO₂ tension gradients showed a close exponential correlation with cardiac output per body weight (CO/BW) during the shedding phase (r=0.85,n=60), although the correlation with CO/BW lessened during the retransfusion phase (r=0.55,n=60). PtcCO₂ was roughly correlated with during hemorrhagic shock, and levels of PtcCO₂ higher than reflected critical tissue perfusion.     

The changes in brain surface,intracerebral tissue,and transconjunctival oxygen tension during hypo- and hyperventilation

To evaluate the validity of organ surface oxygen tension monitoring for assessment of cerebral perfusion, the oxygen tension in brain surface (Pbs_{O 2}), intracerebral tissue (Pic_{O 2}), and conjunctiva (Pcj_{O 2}) were measured simultaneously during hypo- and hyperventilation in dogs, and the comparative study was done.Pbs_{O 2} and Pic_{O 2} significantly increased during hypoventilation and decreased during hyperventilation. And the values of Pbs_{O 2} and Pic_{O 2} were correlated to the corresponding Pa_{CO 2} values significantly (P 0.001 in each case). On the contrary, Pcj_{O 2} did not change significantly during hypo- and hyperventilation.These findings indicate that Pbs_{O 2} as well as Pic_{O 2} could reflect the changes in cerebral perfusion caused by induced hyper- and hypocapnia but that Pcj_{O 2} could not.(Arai T, Silvern DA, Gupte PM et al.: The changes in brain surface intracerebral tissue, and transconjunctival oxygen tension during hypo- and hyperventilation. J Anesth 4: 110–115, 1990)     

Evaluation of transcutaneous oxygen tension monitoring during cosmetic surgery

Transcutaneous oxygen monitoring during rhytidectomy surgery under local anesthesia was evaluated in 18 patients. Blood gas analysis of samples of arterial blood obtained from the superficial temporal arteries during rhytidectomy was compared with transcutaneous PO₂ values. Simple linear regression analysis indicated that the transcutaneous PO₂ correlates strongly with arterial PO₂. Transcutaneous PO₂ monitoring could be a reliable, inexpensive, and continuous method of assessing gradual or sudden changes in arterial PO₂,provided the sensor is fastidiously maintained and properly applied, elements which are critical to relying on this particular device. However, this instrument has no advantages over the digital pulse oximeter.Presented at the American Society for Aesthetic Plastic Surgery, New Orleans, LA, April 15, 1986     

Changes in percutaneous oxygen tension induced by spinal anesthesia

Purpose To check the level of spinal anesthesia is sometimes difficult in patients with dementia. In spinal anesthesia, peripheral oxygen tension may increase in the anesthetized area because of vasodilatation due to sympathetic block. The purpose of this study was to determine whether changes in percutaneous oxygen tension (tcPO₂) were suitable for checking the level of spinal anesthesia. Methods Thirty patients, aged 40 to 70 years, scheduled for surgery of the lower extremities under spinal anesthesia, were enrolled. Spinal anesthesia was performed at L4-5 with hyperbaric 0.5% tetracaine 10 to 12 mg, administered with the patient in the lateral position; the patients were then immediately returned to the supine position. The anesthesia level was checked by cold test 10 min after the spinal anesthesia, and it was confirmed that the upper level was between T3 and T11. Then oxygen 6 l·min⁻¹ was administered by mask. Six electrodes of a tcPO₂ monitor, (TCM 400) were attached before anesthesia, three electrodes at the right, center, and left side of the T3 level, and the other three at the right, center, and left at the T11 level. TcPO₂ was measured before and 10 min after spinal anesthesia, and 5 min after starting oxygen inhalation. Results TcPO₂ increased significantly after spinal anesthesia only at T11, and was increased by oxygen administration at both T3 and T11. The increase of tcPO₂ after oxygen administration was larger at T3 than T11, without any differences in absolute values. Conclusion Measurement of TcPO₂ might be useful as one of the objective methods to distinguish anesthetized and nonanesthetized areas in spinal anesthesia. This study was performed at Ofuna Chuo Hospital.     

Transcutaneous Monitoring of Blood Gas Tensions in Patients on Intermittent Peritoneal Dialysis

A relative contraindication to intermittent peritoneal dialysis (IPD) is chronic lung disease. To evaluate whether the instillation of 2 L of fluid into the peritoneal cavity affects respiratory function, five IPD patients were studied in the supine position during the first 4 h of a routine IPD session. Blood gas tensions were monitored transcutaneously throughout the study period. At the onset of dialysis, mean transcutaneous blood oxygen tension (PtcO2) was 70.6 +/- 9.1 mm Hg. It decreased to 55 +/- 9.9 mm Hg (22% change from basal values) during the instillation of dialysate. Upon drainage, PtcO2 returned to baseline. This sequence of events repeated itself on subsequent exchanges, although with decreasing decrements of PtcO2 with each consecutive exchange (decrease to 58.6 +/- 7.05, 61 +/- 6.5, 63.8 +/- 5.2 mm Hg corresponding to 16%, 12.7%, and 9.6%, respectively, during the second to fourth exchanges). Transcutaneous blood carbon dioxide tension, PtcCO2, showed a very mild increase during the study (33 +/- 7.1 to 38 +/- 6.0 mm Hg). In two patients, the same study protocol was performed during the last 4 h of an IPD session. In these two patients, there was only a 5% variation of PtcO2 from baseline values. These results suggest that an adaptive response to the hypoxemia induced by dialysate instillation rapidly occurs in IPD patients.     

Microvascular regeneration in meshed skin transplants after severe burns

Function of the skin lymphatics as well as blood perfusion of a meshed transplant is crucial for the healing. The lymphatic regeneration and arterial perfusion of skin transplants after severe burns of the extremities had been studied in eight patients by microlymphography, laser doppler perfusion imaging and transcutaneous oxygen pressure measurements 1, 6 and 18 months after transplantation.One month after transplantation, only fragmented as well as many giant lymphatic skin vessels were present in the transplant. After 6 months a normal lymphatic network had developed in all grafts. The extension of the dye in the lymphatics decreased from 4.5 (0-16) at 1 month to 3.0 (1-6) mm after 18 months, indicating improved lymph drainage capacity. The permeability of the lymphatics in the graft was normal. After 1 month, median laser flux in the transplant was 155.6% (105-246%) of the normal skin but it normalised within 18 months. By contrast, transcutaneous oxygen measurement (TcPO₂) increased from 44 (21-47) to 55 (50-76) mmHg.In meshed transplants used to cover severely burned skin morphological and functional normal lymphatics develop within 6 months and the initially increased laser flux due to inflammatory reaction normalises. Our results provide important insights into the healing process of skin transplants after burn.     

Transcutaneous oxygen tension in selection of amputation level

The utility of transcutaneous oxygen tension measurements in selection of a reliable amputation level was evalulated. Measurements were made at the proposed level of amputation in 37 patients, 22 of whom underwent major limb amputation and in 15 amputation was confined to the forefoot or toes. In patients with successful amputation healing, mean transcutaneous oxygen tension on the anterior skin surface was 50 ± 8 mm Hg (index 0.79 ± 0.1 mm Hg). In contrast, patients with failure of healing had a mean transcutaneous oxygen tension of 22 ± 16 mm Hg (index 0.32 ± 0.19 mm Hg) (p < 0.001). Measurements on the posterior or plantar skin surface and posteroanterior differences provided even greater separation between success and failure groups, with no overlap of transcutaneous oxygen tension values or index.Transcutaneous oxygen tension measurement is easily obtained and noninvasive, and can be applied to all patients irrespective of Doppler signals, non-compressible vessels, or painful lesions. Transcutaneous oxygen tension appears to predict successful healing with accuracy, and should be a useful addition to clinical judgment in selection of optimal amputation level.     

Arterialization of epigastric skin flaps in rabbits

Summary This preliminary experimental investigation revealed that arterial blood supply via the inferior epigastric vein (reversed blood flow) nourished an epigastric skin flap well enough to survive. Histological examinations showed no differences between skin of the flap and normal skin (Figs. 4, 5). Free nonvascularised skin flaps (group 1) showed necroses and secondary wound healing. However, the question remains unsolved whether or not the blood flow is re-reversed again postoperatively and how circulation of the flap stabilizes after the first postoperative days.     

Arterial oxygen content regulates plasma erythropoietin independent of arterial oxygen tension: a blinded crossover study

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Limberg皮瓣在面部缺损创面修复中的应用

目的:观察Limberg皮瓣修复面部缺损创面的效果.方法:9例面部肿物切除后皮肤软组织缺损患者设计Limberg皮瓣修复创面.其中肿瘤患者3例;色素痣患者6例.结果:9例患者术后皮瓣均未出现动脉供血和静脉回流障碍,皮瓣色泽、质地较好;伤口Ⅰ期愈合,随访3～6月未见肿物或色素痣复发,瘢痕不明显,形态满意.结论:Limberg皮瓣修复面部中小缺损创面效果良好.设计原则包括:将旋转瓣设计在临近皮肤最松弛区域并且最好完整覆盖一个凸出的美学单位;如果局部旋转后发生猫耳畸形,可以使用皮下蒂皮瓣或者改良的Limberg皮瓣(DuFourmentel皮瓣);如缺损为圆形,用阅读者皮瓣(the reading man procedure)效果可能更好.     

Bipedicled skin flaps for reconstruction of the abdominal wall in newborn omphalocele

Despite technical refinements in surgery and advances in postoperative intensive care, abdominal wall closure in giant omphalocele remains a difficult endeavor. In this respect, bipedicled skin flaps obtained with longitudinal incisions along the margins of the rectus abdominis muscle may represent a good alternative solution to achieve a complete, tension-free midline closure. Incisional areas can subsequently be easily covered with split-thickness thigh grafts. Two neonatal cases were treated with this technique with good results. This has enabled avoidance of palliative coverage as well as complex musculo-cutaneous reconstructions at a later age.     

足部大面积皮肤软组织缺损的皮瓣修复临床分析

目的:比较足部大面积皮肤软组织缺损应用不同类型皮瓣(小腿主干血管逆行皮瓣、皮神经营养血管逆行皮瓣和游离皮瓣)修复的临床效果。方法:57例足部大面积皮肤软组织缺损的患者清创后,应用不同类型的皮瓣进行修复,并比较其成活面积、观察其疗效。其中,小腿主干血管逆行皮瓣14例,面积:7～9cm×11～20cm,平均:8cm×16cm,采用胫后动脉逆行皮瓣3例,腓动脉逆行皮瓣11例;皮神经营养血管逆行皮瓣26例,面积:7～9cm×9～15cm,平均:8cm×11cm,采用腓肠神经营养血管逆行岛状皮瓣23例,隐神经营养血管逆行岛状皮瓣3例;游离皮瓣17例,面积:9.5～15cm×12～28cm,平均:12cm×25cm,采用股前外侧皮瓣13例,隐动脉皮瓣3例,胸背动脉皮瓣1例。结果:57例皮瓣中,完全坏死2例,部分坏死7例,其余全部成活。坏死者全部涉及前足皮肤缺损,其中,主干血管逆行皮瓣完全坏死1例,部分坏死2例;皮神经营养血管逆行皮瓣远端部分坏死5例;游离皮瓣完全坏死1例。统计学分析:皮瓣面积按类型比较(ANOVA),P=0.000,差异有非常显著性意义;皮瓣成活率按类型比较(Kruskal-Wallis Test),P=0.455,差异无显著性意义。经3～18个月随访,所有成活皮瓣血运、外形、质地、功能均满意。结论:大部分足部大面积皮肤软组织缺损可选用皮神经营养血管逆行皮瓣进行修复,但如果涉及前足,特别是缺损较大时,选择游离皮瓣更为适宜。