Myocardial ischemic conditioning: physiological aspects and clinical applications in cardiac surgery

Ischemia-reperfusion is a major determinant of myocardial impairment in patients undergoing cardiac surgery. The main goal of research in cardioprotection is to develop effective techniques to avoid ischemia-reperfusion lesions. Myocardial ischemic conditioning is a powerful endogenous cardioprotective phenomenon. First described in animals in 1986, myocardial ischemic conditioning consists of applying increased tolerance of the myocardium to sustained ischemia by exposing it to brief episodes of ischemia-reperfusion. Several studies have sought to demonstrate its effective cardioprotective action in humans and to understand its underlying mechanisms. Myocardial ischemic conditioning has two forms: ischemic preconditioning [IPC] when the conditioning stimulus is applied before the index ischemia and ischemic postconditioning when the conditioning stimulus is applied after it. The cardioprotective action of ischemic conditioning was reproduced by applying the ischemia-reperfusion stimulus to organs remote from the heart. This non-invasive manner of applying ischemic conditioning has led to its application in clinical settings. Clinical trials for the different forms of ischemic conditioning were mainly developed in cardiac surgery. Many studies suggest that this phenomenon can represent an interesting adjuvant to classical cardioprotection during on-pump cardiac surgery. Ischemic conditioning was also tested in interventional cardiology with interesting results. Finally, advances made in the understanding of mechanisms that underlie the cardioprotective action of ischemic conditioning have paved the way to a new form of myocardial conditioning which is pharmacological conditioning

Ultrasound does not shorten the duration of procedure but provides a faster sensory and motor block onset in comparison to nerve stimulator in infraclavicular brachial plexus block / 대한마취과학회지

BACKGROUND: Infraclaviculr Brachial plexus (ICBP) block is useful for upper extremity surgery. The aim of this study was to compare the ultrasound (US) technique with the nerve stimulation (NS) technique in their success rates and times to perform ICBP block. METHODS: 60 patients undergoing surgery of the upper limb were randomly allocated into two groups (n = 30 per group). Group 1; US, and Group 2; NS. Procedure time (including time for initial ultrasound examination), the success rate and the onset time of sensory and motor blockade were assessed. RESULTS: The time needed to perform the ICBP block is similar in both groups (220 seconds +/- 130 in US group versus 281 +/- 134 seconds in NS group; P = 0.74). The success rate of all the nerve blocks in the US group was 100%. The success rate in the NS group was 73.3%, 76.7%, 76.7% and 100% for radial, ulnar, medial, and musculocutaneous nerve, respectively. A significantly faster onset of sensory block for the radial, ulnar, median, musculocutaneous, and the four nerves considered together were observed. The onset of motor block for the radial, ulnar, and medial nerves was faster in the US group. However, the onset of motor block for the musculocutaneous nerve and the four nerves considered together was comparable between the two groups. CONCLUSIONS: The ultrasound-guided infraclavicular brachial plexus block is a significantly efficacious method with faster onset but similar procedure time compared to the nerve stimulation technique.