Von Willebrand factor hyperactivity affects the outcome of lower limb revascularization in subjects with type 2 diabetes mellitus complicated by diabetic foot vasculopathy: An observational pilot study

Aim of this study is to evaluate any differences in VWF antigen, VWF activity and ADAMTS-13 activity before and after successful and non-successful Percutaneous Transluminal Angioplasty (PTA) in subjects with type 2 diabetes (T2DM) complicated by Chronic limb-threatening ischemia (CLTI) in diabetic foot vasculopathy.

METHODS

In this prospective observational pilot study, we enrolled 35 T2DM subjects who underwent lower limb PTA. Transcutaneous oximetry was performed in all patients before and 6 weeks after PTA. The change in oxygen partial pressure (TcpO2) before and after PTA was expressed as TcpO2-delta (ΔTcpO2). VWF antigen, VWF activity and ADAMTS-13 activity were measured before and 6 weeks after PTA; changes were expressed as delta and ratio from baseline.

RESULTS

Subjects with ∆TcpO2 < 15 mmHg presented higher ΔVWF activity (p = 0.050) and lower ADAMTS-13 activity ratio (p = 0.080). Subjects with ∆TcpO2 < 30 mmHg showed lower ADAMTS-13 activity Δ and ratio (p = 0.028).

CONCLUSIONS

VWF antigen levels and VWF activity may potentially affect PTA outcome. Higher levels of VWF could derive from VWF release as consequence of PTA-induced mechanical endothelial damage and/or oxidative stress-induced modifications of VWF structure with impairment of VWF-ADAMTS13 interactions.

Incoherent optical fluctuation flowmetry for detecting limbs with hemodynamically significant stenoses in patients with type 2 diabetes

INTRODUCTION

The development of new highly accurate, inexpensive and accessible methods for the detection of lower-extremity peripheral artery disease (LE-PAD) in diabetic patients is required. The aim of this study was to evaluate the accuracy of a new incoherent optical fluctuation flowmetry (IOFF) method in detecting legs with hemodynamically significant stenoses compared to ankle brachial index (ABI) and transcutaneous oximetry (TcPO2) in patients with diabetes mellitus (DM).

MATERIALS AND METHODS

Patients were recruited into 2 groups. Group 1 included patients with DM without LE-PAD and/or diabetic foot syndrome; Group 2 included patients with DM and LE-PAD. All patients underwent the following measurements: ultrasound (reference method), ABI, TcPO2, and the new IOFF method.

RESULTS

The new IOFF method showed a sensitivity of 79.5% and a specificity of 89.8% in detecting limbs with hemodynamically significant stenosis (AUC 0.890, CI 0.822-0.957). TcpO2 allows the diagnosis of LE-PAD with 69.2% sensitivity and 86.2% specificity (AUC 0.817, CI 0.723-0.911). Using a standard ABI cut-off of less than 0.9, the sensitivity and specificity for this parameter were 34.5% and 89.7%, respectively. Increasing the diagnostic cut-off of the ABI on the study group to 0.99 improved sensitivity to 84.6% and specificity to 78% (AUC,0.824 CI 0.732-0.915).

CONCLUSIONS

The new IOFF technique has demonstrated high sensitivity and specificity in the detection of LE-PAD in patients with DM. The high accuracy, rapid measurement, and potential availability suggest that the new IOFF method has a high potential for clinical application in the detection of PAD.

Microcirculation and tissue oxygenation in the head and limbs during hyperbaric oxygen treatment

INTRODUCTION

Hyperbaric oxygen (HBO) exposure for 10-15 min has been shown to reduce peripheral blood flow due to vasoconstriction. However, the relationship between decreased peripheral blood flow and the therapeutic effects of HBO treatment on peripheral circulatory disorders remain unknown. Longer exposures have been reported to have vasodilatory effects and increase peripheral blood flow. This study investigated the effect of HBO treatment on blood flow and transcutaneous oxygen pressure (TcPO₂).

METHODS

Twenty healthy volunteers aged 20-65 years (nine males) participated in this study. All participants breathed oxygen for 60 min at 253.3 kPa. Peripheral blood flow using laser Doppler flowmetry and TcPO₂ on the ear, hand, and foot were continuously measured from pre-HBO exposure to 10 min post-exposure.

RESULTS

Peripheral blood flow in each body part decreased by 7-23% at the beginning of the HBO exposure, followed by a slow increase. Post-exposure, peripheral blood flow increased 4-76% in each body part. TcPO₂ increased by 840-1,513% during the exposure period, and remained elevated for at least 10 min after the exposure.

CONCLUSIONS

The findings of the current study suggest vasoconstriction during HBO treatment is transient, and even when present does not inhibit the development of increased tissue oxygen partial pressure. These findings are relevant to studies investigating changes in peripheral blood flow during HBO treatment in patients with circulatory disorders.

Kneeling-induced calf ischemia: a pilot study in apparently healthy European young subjects

PURPOSE

Many tasks, sports or leisure activities require maximal knee flexion. We hypothesized that this position could result in reduced calf perfusion, in young European subjects.

METHODS

We quantified calf ischemia resulting from the knee flexion with transcutaneous oxygen pressure (TcpO2) sensors by assessing the decrease from rest of TcpO2 (DROP) defined as limb changes minus chest changes. A minimal DROP (DROPm) <-15 mmHg defines the presence of ischemia. From the crawling position, participants kneeled for 3 min while bending as in prostration/prayer position (P). Thirty-five participants repeated this maneuver a second time, while 7 participants were also required to sit on their heels with the torso in the vertical position to attain knee flexion without significant groin flexion (S).

RESULT

In 41 healthy young volunteers (30 males), 25 [20-31] years old, 37 patients showed a DROPm < -15 mmHg from "R" to "P" in one (n = 4) or both (n = 33) calves (90.2%; 95% CI 76.9-97.3). After backward regression of the DROPm, there was no significant association with side, body weight of systolic blood pressure. However, age was strongly associated with DROPm (OR 5.34 [2.45-8.69]) so that DROPm was significantly higher in older, with a correlation ρ = 0.31 (p = 0.003).

CONCLUSION

Kneeling dramatically reduces calf perfusion, likely through popliteal artery kinking, possibly through muscle crushing. Eastern lifestyle includes routine flexed position since childhood. Whether or not such a chronic training reduces the risk of kneeling-induced ischemia in adults is unknown to date.

Comparison of tissue oxygenation achieved breathing oxygen using different delivery devices and flow rates

INTRODUCTION

Divers with suspected decompression illness require high concentration oxygen (O₂). There are many different O₂ delivery devices, with few data comparing their performance. This study evaluated O₂ delivery, using tissue O₂ partial pressure (P_tcO₂), in healthy divers breathing O₂ via three different delivery devices.

METHODS

Twelve divers had P_tcO₂ measured at six limb sites. Participants breathed O₂ from: a demand valve using an intraoral mask with a nose clip (NC); a medical O₂ rebreathing system (MORS) with an oronasal mask and with an intraoral mask; and a non-rebreather mask (NRB) at 15 or 10 L·min⁻¹ O₂ flow. In-line inspired O₂ F_IO₂) and nasopharyngeal F_IO₂ were measured. Participants provided subjective ratings of device comfort, ease of breathing, and overall ease of use.

RESULTS

P_tcO₂ values and nasopharyngeal FIO₂ were similar with the demand valve with intraoral mask, MORS with both masks and the NRB at 15 L·min⁻¹. P_tcO₂ and nasopharyngeal F_IO₂ values were significantly lower with the NRB at 10 L·min⁻¹. The NRB was rated as the most comfortable to wear, easiest to breathe with, and overall the easiest to use.

CONCLUSION

Of the commonly available devices promoted for O₂ delivery to injured divers, similar PtcO₂ and nasopharyngeal F_IO₂ values were obtained with the three devices tested: MORS with an oronasal or intraoral mask, demand valve with an intraoral mask and NRB at a flow rate of 15 L·min⁻¹. P_tcO₂ and nasopharyngeal F_IO₂ values were significantly lower when the flow rate using the NRB was decreased to 10 L·min⁻¹.

Comparison of tissue oxygenation achieved breathing oxygen from a demand valve with four different mask configurations

INTRODUCTION

High concentration normobaric oxygen (O₂) is a priority in treating divers with suspected decompression illness. The effect of different O₂ mask configurations on tissue oxygenation when breathing with a demand valve was evaluated.

METHODS

Sixteen divers had tissue oxygen partial pressure (PtcO₂) measured at six limb sites. Participants breathed O₂ from a demand valve using: an intraoral mask (IOM®) with and without a nose clip (NC), a pocket face mask and an oronasal mask. In-line inspired O₂ (FIO₂) and nasopharyngeal FIO₂ were measured. Participants provided subjective ratings of mask comfort, ease of breathing and holding in position.

RESULTS

PtcO₂ values and nasopharyngeal FIO₂ (median and range) were greatest using the IOM with NC and similar with the IOM without NC. O₂ measurements were lowest with the oronasal mask which also was rated as the most difficult to breathe from and to hold in position. The pocket face mask was reported as the most comfortable to wear. The NC was widely described as uncomfortable. The IOM and pocket face mask were rated best for ease of breathing. The IOM was rated as the easiest to hold in position.

CONCLUSION

Of the commonly available O₂ masks for use with a demand valve, the IOM with NC achieved the highest PtcO₂ values. PtcO₂ and nasopharyngeal FIO₂ values were similar between the IOM with and without NC. Given the reported discomfort of the NC, the IOM without NC may be the best option.

Effect of mechanical vibration on transcutaneous oxygen levels in the feet of type 2 diabetes mellitus patients

BACKGROUND AND OBJECTIVE

Foot conditions in patients with diabetes mellitus (DM) are major causes of morbidity and disability. Whole body vibration may promote blood circulation in the lower limbs, hence facilitating perfusion and promoting the supply of nutrients and oxygen to comprised tissues. Transcutaneous oxygen levels (TcPO₂)>40mmHg in cases of diabetic foot syndrome are associated with a good prognosis in the resolution of ulcers. The objective of this study was to determine whether whole body vibration favors some parameters of interest related to complications associated with the diabetic foot syndrome.

PATIENTS AND METHODS

Fifty-four patients with DM were included in a 12-week exercise program based on whole body vibration. Glycemic control was determined on the basis of the patients' levels of glycated hemoglobin (HbA_1c); sensitivity and TcPO₂ levels of each foot were also recorded. Assessments were performed prior to initiating the whole body vibration program and at the end of it.

RESULTS

No significant changes were observed in the patients' HbA_1c (P=.442) levels or sensitivity (P=.07). A significant 7mmHg increase (P<.0001; effect size: d=0.53) was observed in the concentration of TcPO₂.

CONCLUSIONS

Whole body vibration may increase TcPO₂ levels with useful implications for the prevention or management of complications associated with restricted blood perfusion in the diabetic foot syndrome.

Rearfoot Transcutaneous Oximetry is a Useful Tool to Highlight Ischemia of the Heel

PURPOSE

To demonstrate the usefulness of rearfoot transcutaneous oximetry to assess the peripheral arterial disease in diabetic patients with heel ulcer.

METHODS

From our database of 550 critical limb ischemia diabetic patients followed after a percutaneous transluminal angioplasty, we have selected patients with below the knee arterial disease. Patients were grouped according to the dorsal transcutaneous oximetry value (Group A < 30 mmHg; Group B ≥ 30 mmHg). Patients of Group B had a second oximetry performed at the rearfoot, close to the lesion localized in all cases at the heel. Finally, the analysis of the arterial pattern disease has been done.

RESULTS

We selected 191 patients: Group A (151 patients), dorsal transcutaneous oximetry of 11.8 ± 0.7 mmHg; Group B (40 patients), dorsal transcutaneous oximetry of 44.2 ± 10.1 mmHg. In Group B, rearfoot oximetry was 20.5 ± 5 mmHg, significantly lower than dorsal oximetry (p = 0.0179). The anterior tibial artery was involved in all patients of Group A. In Group B, the anterior tibial artery was involved in 15 subjects and never alone; the posterior tibial artery was involved in 20 subjects and in 11 cases alone. The peroneal artery was affected in 20 subjects and in 14 patients alone.

CONCLUSION

When a heel lesion is present and the transcutaneous oximetry recorded on the dorsum of the foot does not confirm the presence of critical limb ischemia (not ≤30 mmHg), a second oximetry recorded on the rearfoot is useful to point out ischemia of the peroneal artery and/or of the posterior tibial artery.

Transcutaneous oximetry: normal values for the lower limb

INTRODUCTION

Current guidelines for transcutaneous oximetry measurement (TCOM) for the lower limb define tissue hypoxia as a transcutaneous oxygen partial pressure < 40 mmHg. Values obtained with some newer machines and current research bring these reference values into question.

AIM

To determine 'normal' TCOM values for the lower limb in healthy, non-smoking adults using the TCM400 oximeter with tc Sensor E5250.

METHOD

Thirty-two healthy, non-smoking volunteers had TCOM performed at six positions on the lower leg and foot. Measurements were taken with subjects lying supine breathing air, then with leg elevated and whilst breathing 100 % oxygen.

RESULTS

Room-air TCOM values (mean mmHg, 95 % confidence interval (CI) ) were: lateral leg 41.3, CI 37.8 to 44.7; lateral malleolus 38.6, CI 34.1 to 43.1; medial malleolus 43.9, CI 40.2 to 47.6; dorsum, between first and second toe 39.3, CI 35.9 to 42.7; dorsum, proximal to fifth metatarsal-phalangeal joint 46.4, CI 43.4 to 49.3; plantar 52.3, CI 49.6 to 55.1. Using the currently accepted value of less than 40 mmHg for tissue hypoxia, 24 of our 32 'healthy' subjects had at least one air sensor reading that would have been classified as hypoxic. Seventeen subjects had TCOM values less than 100 mmHg when breathing 100 % normobaric oxygen.

CONCLUSION

Normal lower limb TCOM readings using the TCOM400 with tc Sensor E5250 may be lower than 40 mmHg, used to define tissue hypoxia, but consistent with the wide range of values found in the literature. Because of the wide variability in TCOM at the different sensor sites we cannot recommend one TCOM value as indicative of tissue hypoxia. A thorough clinical assessment of the patient is essential to establish appropriateness for hyperbaric oxygen treatment, with TCOM used as an aid to help guide this decision, but not as an absolute diagnostic tool.