[Remote Ischemic Conditioning - Endogenous Tissue Protection and its Possible Applications in Surgery]

Tissue perfusion is pivotal to wound healing and tissue regeneration after surgery. Ischemia and reperfusion lead to inflammatory reactions with consecutive tissue damage and necrosis. Multiple conditioning techniques have been described to protect tissue from those damaging mechanisms in the perioperative period. However, most of these fail to meet the requirements of a good therapeutic effect, time and cost efficiency, non-invasiveness and applicability without the need for additional devices or drugs. Remote ischemic conditioning (RIC) is a technique to provide endogenous tissue protection, which fully meets those requirements. Repeated, short cycles of ischemia/reperfusion applied to a circumscribed vascular territory lead to the activation of endogenous signal pathways resulting in increased tolerance to hypoperfusion and limiting the damage caused by reperfusion, even in tissues located far away from the conditioned area. The non-invasive application of the conditioning stimulus requires no more than a pressure cuff, which is placed on the upper arm and is repeatedly inflated to suprasystolic pressures. Different concepts of remote ischemic pre-, peri- and postconditioning enable the usage in both elective and emergency surgical interventions. Based on encouraging experimental studies, the application of RIC has increased in the clinical setting. In addition to studies addressing cardio-, nephro- or neuroprotection there are some initial findings supporting a potential beneficial application in reconstructive microsurgery. This article aims to give an overview of the development, concepts and mechanisms of RIC with a focus on its clinical application in the field of surgery.

Upper extremity ischemia is superior to lower extremity ischemia for remote ischemic conditioning of antero-lateral thigh cutaneous blood flow

Remote ischemic conditioning (RIC) is known to improve microcirculation in various settings, but little is known about the impact of the amount of ischemic tissue mass or the limb itself. Since ischemia and subsequent necrosis of flaps is one of the most dreaded complications in reconstructive surgery, adjuvant methods to improve microcirculation are desirable. We therefore performed a randomized trial to compare the effect of arm versus leg ischemia for RIC of the cutaneous microcirculation of the antero-lateral thigh. Forty healthy volunteers were randomized to undergo 5 min of ischemia of either the upper or lower extremity, followed by 10 min of reperfusion.Ischemia was induced by a surgical tourniquet applied to the proximal limb, which was inflated to 250 mmHg for the upper and 300 mgHg for the lower extremity. This cycle was repeated a total of three times. Cutaneous microcirculation was assessed by combined laser doppler spectrophotometry on the antero-lateral aspect of the thigh to measure cutaneous blood flow (BF), relative hemoglobin content (rHb), and oxygen saturation (StO2). Baseline measurements were performed for 10 min, after which the ischemia/reperfusion cycles were begun. Measurements were performed continuously and were afterwards pooled to obtain a mean value per minute. Both groups showed significant increases in all three measured parameters of cutaneous microcirculation after three cycles of ischemia/reperfusion when compared to baseline (BF: 95.1% (P < 0.001) and 27.9% (P = 0.002); rHb: 9.4% (P < 0.001) and 5.9% (P < 0.001), StO2: 8.4% (P = 0.045) and 9.4% (P < 0.001). When comparing both groups, BF was significantly higher in the arm group (P = 0.019 after 11 min., P = 0.009 after 45 min). In conclusions, both ischemic conditioning of the upper and lower extremity is able to improve cutaneous BF on the ALT donor site. However, RIC of the upper extremity seems to be a superior trigger for improvement of cutaneous BF.

[Wound healing complications in smokers, non-smokers and after abstinence from smoking]

BACKGROUND

The pulmonary and cardiovascular ramifications of smoking are well documented and this also applies to increased wound healing complications in smokers. The aim of this study was to ascertain whether preoperatively refraining from smoking would affect the incidence of wound healing disorders.

MATERIAL AND METHODS

Between 2006 and 2008 a total of 295 patients underwent aesthetic (n = 167) or reconstructive surgery (n = 128). They were divided into three groups: A (n = 98) non-smokers for at least 2 years, B (n = 99) patients who refrained from smoking 6 weeks prior to surgery and C (n = 98) smokers. Smoking abstinence was verified by cotinine tests. Wound healing complications were defined as dehiscent wounds, wound infections, atypical scar formation and adiponecrosis.

RESULTS

Smokers developed wound healing complications in 48.2% of cases, non-smokers in 21.0% and patients who had stopped smoking for 6 weeks in 30.8% of cases (p = 0.006).

CONCLUSION

Elective surgery should only be performed on non-smokers and smokers who had refrained from smoking for at least 6 weeks to reduce wound healing complications as far as possible.

[Three case reports of frostbite. Management and literature]

Due to social and demographic changes as well as new leisure activities, the number of frostbite injuries in the general population is on the increase. Because the injuries are primarily located on the hands and feet the consequences for those concerned are devastating. We provide help in grading and introduce concrete therapeutic regimes for frostbite which are illustrated by three case reports from our clinical experience with varying risk profiles.

[Aneurysm of the radial artery in a patient with marfan syndrome]

We present a 52-year-old male patient suffering from Marfan syndrome who developed an aneurysm of the distal radial artery. The histology showed the typical marfanoid structure of a thrombosed aneurysm. As far as we know, this is the first description of a hand aneurysm in a patient with Marfan syndrome.