Radosław Marciniak

Randomized, comparative study of the effectiveness of three different techniques of interscalene brachial plexus block using 0.5% ropivacaine for shoulder arthroscopy

BACKGROUND Interscalene brachial plexus block is an effective regional anesthesia technique for shoulder surgeries. The superiority of the popular ultrasound-guided blocks over peripheral nerve stimulator-confirmed blocks remains unclear. In this study the efficacy of these different block techniques was compared. METHODS This prospective, randomized, clinical study included 109 patients (ASA grades I-III) who receive 20 mL 0.5% ropivacaine with ultrasound-guided blocks (U group), peripheral nerve stimulator-confirmed blocks (N group), or ultrasound-guided and peripheral nerve stimulator-confirmed blocks (dual guidance; NU group) for elective shoulder arthroscopy. Block onset time, duration, and effectiveness on the Lovett rating scale were assessed. RESULTS There was no statistically significant intergroup difference in duration of block performance, irrespective of the technique (P = 0.232). Onset time of complete warmth sensation loss (P < 0.001) and muscle strength abolition (P < 0.001) was significantly longer and mean Lovett rating scale score distribution was significantly higher in the N group than in the other groups (P < 0.001). These findings show a statistically significant correlation between the performance of the used block technique and the necessity of conversion to general anesthesia because of insufficient block in the N group (58.54%) than in the U (24.44%) and NU (19.57%) groups. CONCLUSIONS Peripheral nerve stimulator-confirmed needle placement is not necessary to ensure effectiveness of ultrasound-guided blocks, which is expressed as a lack of necessity of conversion to general anesthesia. Nevertheless, the dual guidance technique is recommended to reduce the risk of complications and might be considered the regional anesthesia of choice for shoulder surgery.

Estimation of the propagation direction and spectral properties of the EEG signals registered during sevoflurane anaesthesia using Directed Transfer Function method

Estimation of the propagation direction and spectral properties of the EEG signals registered during sevoflurane anaesthesia using Directed Transfer Function method The aim of this study was to estimate spectral properties and propagation of the EEG signals registered during sevoflurane anaesthesia between individual EEG recording channels. The intensities of activity flows were calculated for delta, theta, alpha and beta waves using the Directed Transfer Function integration procedure. It was found that delta waves played the dominant role in the EEG signal propagation during anesthesia and it was suggested that theta and alpha waves propagation could be related to the processes participating in the wakefulness control. Data obtained with DTF method were compared with data received from the analysis of cerebral blood flow with the use of PET in other laboratory. This study showed that analysis of the EEG signal propagation is useful for better understanding and thus safer induction of anaesthesia procedure.

Characteristic features of the EEG patterns during anaesthesia evoked by fluorinated inhalation anaesthetics

The presence of the EEG patterns showing some similarities with epileptiform activity as well as epileptic EEG discharges and motor seizures observed in some people during anaesthesia conducted with volatile anaesthetics indicate the necessity of better understanding the nature of these patterns. In this research EEG analysis was performed in the group of twelve adult patients without history of neurological diseases. Anaesthesia was induced with propofol. After laryngeal mask insertion the anaesthesia was maintained with mixture of air/oxygen with either isoflurane, sevoflurane or desflurane. EEG patterns during anaesthesia were evaluated using different methods of signal analysis: Higuchi’s fractal dimension, mean phase coherence, time-frequency distributions (spectrograms and scalograms) and time and frequency marginals extracted from scalograms. The purpose of this research was to demonstrate evolution of the EEG activity in the course of anaesthesia. The contribution of the alpha waves in the overall EEG pattern was gradually decreasing with increasing depth of anaesthesia with complete suppression during the deepest level of anaesthesia. The amount of alpha activity was increasing again when the patient was awakening. Diminishing of the alpha wave contribution to the overall EEG pattern corresponded to the fractal dimension decrease. Fractal dimension increased again in the burst-suppression region. Mean interhemispheric phase coherence for the anterior (frontal) as well as posterior (parieto-occipital) derivations rapidly decreased during burst-suppression activity. Correlation between spectral power, fractal dimension and mean phase coherence and the concentration of volatile anaesthetic was observed. In frequency marginals two distinctive frequencies: 5 Hz and 3 Hz were observed- the dominant 5 Hz frequency waves in frontal derivations reflecting bursts of electrical activity during deep anaesthesia.

Detection of the EEG spike-wave patterns evoked by volatile anaesthetics

The goal of this work is automatic detection of spike-wave patterns in EEG-signal evoked by volatile anesthetics (isoflurane, sevoflurane or desflurane). The EEG-signal was translated into a sequence of symbols coding information about fragments of records with EEG patterns detected as spike-wave forms. Their shape was described by only four parameters such as mobility of the form, spike variance, wave slope and sum of wave amplitudes. The sensivity of 0.84 and specifity of 0.93 were received.

Correlation of Depth of Anesthesia Indexes with MAC in Volatile Anesthesia

The aim of this study is to investigate the effectiveness of the commercial EEG-based indexes (BIS, SE/RE, AEP) and the sample entropy measure in assessing the depth of anesthesia in case of different agents (isoflurane, desflurane and sevoflurane) and induction protocols (propofol, VIMA, VCRII). The relationships between the indexes and the anesthetic concentration were quantified in 82 orthopedic patients using the linear Pearsons correlation coefficient and the Spearman’s rank correlation coefficient. The highest Spearman’s rank correlation coefficient was observed for the SE in sevoflurane, and for RE in isoflurane and desflurane anesthesia. If the linear Pearson’s correlation coefficient is considered, BIS gives better correlation in isoflurane and desflurane, and SE in sevoflurane anesthesia.

Randomised controlled trial of analgesic effectiveness of three different techniques of single-shot interscalene brachial plexus block using 20 mL of 0.5% ropivacaine for shoulder arthroscopy

BACKGROUND Shoulder arthroscopic procedures impose a challenge to anaesthesiologists in terms of postoperative analgesia. Proper pain management after arthroscopic procedures improves patient satisfaction and facilitates early rehabilitation. METHODS We performed a randomized, prospective clinical study to assess the influence of anthropometric parameters and IBPB technique on the quality of postoperative analgesia. A total of 106 randomly selected patients of ASA I-III status scheduled for elective shoulder arthroscopy. Reasons for exclusion were neurological deficit in the upper arm, allergies to amide-type local anesthetics, coagulopathy, and pregnancy.The patients received 20 mL of 0.5% ropivacaine for an ultrasound-guided interscalene brachial plexus block (IBPB) (group U), peripheral nerve stimulation (PNS)-confirmed IBPB (group N), or ultrasound-guided, PNS-confirmed IBPB (dual guidance; group NU). RESULTS We observed that the three groups did not differ in mean time of sensory and motor block terminations. In individual cases in each group, sensory block lasted up to 890-990 minutes, providing satisfactory long lasting postoperative analgesia in patients receiving IBPB. We observed a negative correlation between body mass index and termination of motor block (P = 0.037, Pearsons correlation coefficient) and a positive correlation between age and termination of sensory block (P = 0.0314, Pearsons correlation coefficient) in group U compared to the other two groups. We found a positive correlation between male gender and termination of motor block (P = 0.0487, Pearsons correlation coefficient) in group N compared to the other two groups. CONCLUSION In our study, patients received satisfactory analgesia in the postoperative period regardless of technique used, age, gender, or potentially uncommon anthropometry.

Effects of volatile anaesthetics concentration on spectro-temporal pattern of EEG

The aim of this study was to compare the effects of volatile anaesthetics (isoflurane, desflurane and sevoflurane) on spectro-temporal pattern of EEG registered in 75 patients. The relationships between the relative powers calculated for the frequency bands: delta (1-3 Hz), theta (4-7 Hz), alpha (8-13 Hz) and beta (14-25 Hz) and the anaesthetics concentrations were identified. Increasing concentration produced increases in delta and theta waves powers accompanied by the decreases in the powers of alpha and beta ones. Comparing branches of increasing and decreasing concentration the hysteresis phenomenon, i.e. systematic decrease or increase of each waves powers differently for each of the fluorinated inhalation anaesthetics, was observed at the end of anaesthesia. Moreover, a biphasic effect, i.e. an initial increase followed by a decrease of high frequency activity with a simultaneous increase in low frequency activity was observed for propofol induced before the start of volatile anaesthesia.