Impact of the pericapsular nerve group (PENG) block on postoperative analgesia and functional recovery following total hip arthroplasty: a randomised, observer-masked, controlled trial.

The pericapsular nerve group (PENG) block is a novel regional anaesthesia technique that aims to provide hip analgesia with preservation of motor function, although evidence is currently lacking. In this single-centre, observer-masked, randomised controlled trial, patients undergoing total hip arthroplasty received pericapsular nerve group block or no block (control group). Primary outcome measure was maximum pain scores (0-10 numeric rating scale) measured in the first 48 h after surgery. Secondary outcomes included postoperative opioid consumption; patient mobilisation assessments; and length of hospital stay. Sixty patients were randomly allocated equally between groups. The maximum pain score of patients receiving the pericapsular nerve group block was significantly lower than in the control group at all time-points, with a median (IQR [range]) of 2.5 (2.0-3.7 [0-7]) vs. 5.5 (5.0-7.0 [2-8]) at 12 h; 3 (2.0-4.0 [0-7]) vs. 6 (5.0-6.0 [2-8]) at 24 h; and 2.0 (2.0-4.0 [0-5]) vs. 3.0 (2.0-4.7 [0-6]) at 48 h; all p < 0.001. Moreover, the pericapsular nerve group showed a significant reduction in opioid consumption, better range of hip motion and shorter time to ambulation. Although no significant difference in hospital length of stay was detected, our results suggest improved postoperative functional recovery following total hip arthroplasty in patients who received pericapsular nerve group block.

Failed back surgery syndrome: a new strategy by the epidural injection of MESNA.

PURPOSE: Evaluate the efficacy and safety of MESNA (sodium 2-mercaptoethanesulfonate) injection into the epidural space in the FBSS. METHODS: We designed a prospective phase II longitudinal study. Six consecutive patients were enrolled. Patients underwent one peridural injection per week for 3 weeks. NRS and ODI were investigated before and 48 h after injections, and at 1 week, 1 month and 2 months after the last procedures. Opioids intake is investigated before procedures and 1 week, 1 month and 3 months after the last procedures. Lumbosacral MRI is performed before the first procedure, at the end and 3 months after the last procedures. RESULTS: From baseline, at 3 months, NRS in standing, sitting and lying position improved, respectively, of 34.29, 30.56 and 26.47%; ODI improved of 20.3%; the average decrease in morphine intake was 20.54%. No difference in MR images was found. Conclusions Our preliminary results suggest that MESNA might be an efficacy alternative to common practice.

Ex vivo animal-model assessment of a non-invasive system for loss of resistance detection during epidural blockade.

During recent decades epidural analgesia has gained widespread recognition in many applications. In this complex procedure, anaesthetist uses a specific needle to inject anesthetic into the epidural space. It is crucial the appropriate insertion of the needle through inhomogeneous tissues placed between the skin and the epidural space to minimize anesthetic-related complications (e.g., nausea, headache, and dural puncture). Usually, anaesthetists perform the procedure without any supporting tools, and stop pushing the syringe when they sense a loss of resistance (LOR). This phenomenon is caused by the physical properties of the epidural space: the needle breaks the ligamentum flavum and reaches the epidural space, in this stage the anaesthetist perceives a LOR because the epidural space is much softer than the ligamentum flavum. To support the clinician in this maneuver we designed a non-invasive system able to detect the LOR by measuring the pressure exerted on the syringe plunger to push the needle up to the epidural space. In a previous work we described the system and its assessment during in vitro tests. This work aims at assessing the feasibility of the system for LOR detection on a more realistic model (ex vivo pig model). The system was assessed by analyzing: its ability to hold a constant value (saturation condition) during the insertion of the needle, and its ability to detect the entrance within the epidural space by a decrease of the system's output. Lastly, the anaesthetist was asked to assess how the ex vivo procedure mimics a clinical scenario. The system reached the saturation condition during the needle insertion; this feature is critical to avoid false positive during the procedure. However, it was not easy to detect the entrance within the epidural space due to its small volume in the animal model. Lastly, the practitioner found real the model, and performed the procedures in a conventional manner because the system did not influence his actions.

Bronchial blockers under pressure: in vitro model and ex vivo model.

BACKGROUND: Pressures (Pe) exerted by bronchial blockers on the inner wall of the bronchi may cause mucosal ischaemia. Our aims were as follows: (i) to compare the intracuff pressure (Pi) and Pe exerted by commercially available bronchial blockers in an in vitro and an ex vivo model; (ii) to investigate the influence of both the inflated intracuff volume and cuff diameter on Pe; and (iii) to estimate the minimal sealing volume (VSmin) and the corresponding Pe for each bronchial blocker studied. METHODS: The Pe exerted by seven commercial bronchial blockers was measured at different inflation volumes using a custom-designed system using in vitro and ex vivo animal models with two internal diameters (12 and 15 mm). RESULTS: In the same conditions, Pi was significantly lower than Pe (P<0.05), and Pe was higher in the in vitro model than in the ex vivo model. The Pe increased with the inflated volume, with use of the small-diameter model (P<0.05). Ex vivo models needed a higher minimal sealing volume than the in vitro models, and this volume increased with the diameter (e.g. the VSmin at a positive pressure of 25 cm H2O required a Pe ranging from 12 to 78 mm Hg on the 15 mm ex vivo model and from 66 to 110 mm Hg on the 12 mm ex vivo model). CONCLUSIONS: The Pi cannot be used to approximate Pe. The diameter of the model, the inflated volume, and the bronchial blocker design all influence Pe. A pressure higher than the critical ischaemic threshold (i.e. 25 mm Hg) was needed to prevent air leak around the cuff in the in vitro and ex vivo models.

A cost-effective, non-invasive system for pressure monitoring during epidural needle insertion: Design, development and bench tests.

Epidural blockade procedures have gained large acceptance during last decades. However, the insertion of the needle during epidural blockade procedures is challenging, and there is an increasing alarming risk in accidental dural puncture. One of the most popular approaches to minimize the mentioned risk is to detect the epidural space on the base of the loss of resistance (LOR) during the epidural needle insertion. The aim of this paper is to illustrate an innovative and non-invasive system able to monitor the pressure exerted during the epidural blockade procedure in order to detect the LOR. The system is based on a Force Sensing Resistor (FSR) sensor arranged on the top of the syringe's plunger. Such a sensor is able to register the resistance opposed to the needle by the different tissues transducing the pressure exerted on the plunger into a change of an electrical resistance. Hence, on the base of a peculiar algorithm, the system automatically detects LOR providing visual and acoustic feedbacks to the operator improving the safety of the procedure. Experiments have been performed to characterize the measurement device and to validate the whole system. Notice that the proposed solution is able to perform an effective detection of the LOR.

Design and characterization of a measurement system for monitoring pressure exerted by bronchial blockers: In vitro trials.

Bronchial blockers (BBs) allow occluding the bronchial duct and collapsing the "dependent" lung in a number of thoracic surgery. The occlusion is obtained through a cuff that, inflated with a proper air volume, exerts a pressure, Pe, on the inner wall of the mainstem bronchus. In this work a measurement chain, based on two piezorestistive force sensors, was developed and calibrated to measure Pe exerted by six BBs, as a function of inflated volume on in vitro models (two latex ducts with diameters similar to the ones of the adult mainstem bronchi: 12 mm and 15 mm). Pe showed wide changes considering different BBs, and significantly increases with the decrease of the model's diameter, at the same inflated volume. Lastly, the minimum occlusive volume (MOV) to sail the two models was estimated for each BB. These experiments were performed by applying a pressure difference across the cuff of 25 cmH2O, in order to simulate the worst condition in a clinical scenario. Results show that MOV depends on both the type of BB and the duct diameter. The knowledge of this volume allows estimating the minimum value of Pe exerted by BBs to avoid air leakage.

Force and pressure distribution using Macintosh and GlideScope laryngoscopes in normal airway: an in vivo study.

BACKGROUND: Forces applied on oropharyngeal soft tissues by direct laryngoscopy may cause damage to the patients. The aim of this study was to measure the forces applied during the manoeuvres to achieve glottis visualization and tracheal intubation, comparing direct laryngoscopy and videolaryngoscopy in vivo. METHODS: Thirty adult patients (ASA physical status 1 or 2, BMI between 18 and 30 kg/m2, no difficulty to intubate) were randomly and blindly assigned to one of two groups. Forces and pressure distribution applied during glottis visualization and intubation were measured using film pressure transducers, comparing Macintosh direct laryngoscope and GlideScope videolaryngoscope. RESULTS: Fifteen patients from each group, all with Cormack-Lehane grade 1 view, were analyzed. Forces applied during the intubation with the GlideScope were significantly lower than forces applied with the Macintosh (8+4 N vs. 40+14 N, respectively, P<0.001). Considering the Macintosh laryngoscope, the minimal force applied for glottis visualization was significantly lower than the one applied for intubation (16+6 N vs. 40+14 N, respectively, P<0.005). When using the Macintosh laryngoscope, forces were concentrated mostly on the tip, whereas with the GlideScope forces' concentration in a particular area was not observed. CONCLUSION: Our study shows that in patients with normal airways the GlideScope allows a view of glottis and permits a successful tracheal intubation applying lower force (significantly in intubation) as compared to the Macintosh laryngoscope. Also, the GlideScope probe distributes the forces more homogeneously to the tissue thus further reducing the potential for tissue damage.

Force and pressure distribution using Macintosh and GlideScope laryngoscopes in normal and difficult airways: a manikin study.

BACKGROUND: The forces applied to the soft tissues of the upper airway may have a deleterious effect. This study was designed to evaluate the performance of the GlideScope compared with the Macintosh laryngoscope. METHODS: Twenty anaesthetists and 20 trainees attempted tracheal intubation of a Laerdal SimMan manikin. Forces and pressure distribution applied by both laryngoscope blades onto the soft upper airway tissues were measured using film pressure transducers. The minimal force needed to achieve a successful intubation, in the same simulated scenario, was measured; additionally, we considered the visualization score achieved by using the Cormack-Lehane grades. RESULTS: All participants applied, on average, lower force with the GlideScope than with the Macintosh in each simulated scenario. Forces [mean (sd)] applied in the normal airway scenario [anaesthetists: Macintosh 39 (22) N and GlideScope 27 (15) N; trainees: Macintosh 45 (24) N and GlideScope 21 (15) N] were lower than forces applied in the difficult airway scenario [anaesthetists: Macintosh 95 (22) N and GlideScope 66 (20) N; trainees: Macintosh 100 (38) N and GlideScope 48 (16) N]. All the intubations using the GlideScope were successful, regardless of the scenario and previous intubation experience. The average pressure on the blades was 0.13 MPa for the Macintosh and 0.07 MPa for the GlideScope, showing a higher uniformity for the latter. CONCLUSIONS: The GlideScope allowed the participants to obtain a successful intubation applying a lower force. A flatter and more uniform pressure distribution, a higher successful rate, and a better glottic view were observed with the GlideScope.

Cardiac output estimation in mechanically ventilated patients: a comparison between prolonged expiration method and thermodilution.

A non-invasive method to estimate cardiac output (CO) in mechanically ventilated patients, based on prolonged expiration, has been previously described. With the aim to assess its performances, we prospectively enrolled fifteen cardiac surgery patients, and compared the results obtained with the non-invasive method with the ones obtained using two invasive approaches based on thermodilution. The correlations between the prolonged expiration method with both the thermodilution-based ones show high values (ρ(2)>0.77 and ρ(2)>0.89). This encouraging agreement is also confirmed by the closeness between the measured values of CO: the mean differences considering all patients and the two reference invasive techniques are -0.8 % and -7.5 %. These values show the slight underestimation of CO by the proposed non-invasive method with respect to the gold standard. On the other hand the described method could represent a good compromise between accuracy and non-invasiveness, which fosters the implementation of a new monitoring tool suitable for a semi-continuous CO assessment.

Influence of ventilatory settings on indirect calorimetry in mechanically ventilated patients.

With the aim to assess metabolic monitor's suitability to the use in mechanically ventilated patients, a method, based on the comparison between the measurements performed by the monitor and the ventilator, is here described. In particular, the effects of positive end-expiratory pressure and oxygen inspiratory fraction (FiO(2)) on the metabolic measurements in presence of bias flow are investigated. In this study a metabolic monitor is used to estimate the energy expenditure of 10 mechanically ventilated cardiosurgical patients at different positive end-expiratory pressure, FiO(2) and two different modes of ventilation, with bias flow. The influence of the ventilatory settings on the parameters measured by the monitor is here quantified: a slight decrease of respiratory quotient and a slight increase of resting energy expenditure are observed with the increase of FiO(2). This study shows a good agreement between the measurements of the two devices: FiO(2), expiratory volume (mean difference lower than 3%), and respiratory frequency (mean difference lower than 1%). This also demonstrates the capability of the metabolic monitor to reject the effect of the bias flow.

Postoperative pain treatment SIAARTI Recommendations 2010. Short version.

The aim of these recommendations is the revision of data published in 2002 in the "SIAARTI Recommendations for acute postoperative pain treatment". In this version, the SIAARTI Study Group for acute and chronic pain decided to grade evidence based on the "modified Delphi" method with 5 levels of recommendation strength. Analgesia is a fundamental right of the patient. The appropriate management of postoperative pain (POP) is known to significantly reduce perioperative morbidity, including the incidence of postoperative complications, hospital stay and costs, especially in high-risk patients (ASA III-V), those undergoing major surgery and those hospitalized in a critical unit (Level A). Therefore, the treatment of POP represents a high-priority institutional objective, as well as an integral part of the treatment plan for "perioperative disease", which includes analgesia, early mobilization, early enteral nutrition and active physiokinesitherapy (Level A). In order to improve an ACUTE PAIN SERVICE organization, we recommend: --a plan for pain management that includes adequate preoperative evaluation, pain measurement, organization of existing resources, identification and training of involved personnel in order to assure multimodal analgesia, early mobilization, early enteral nutrition and active physiokinesitherapy (Level A); --the implementation of an Acute Pain Service, a multidisciplinary structure which includes an anesthetist (team coordinator), surgeons, nurses, physiotherapists and eventually other specialists; --referring to high-quality indicators in establishing an APS and considering the following key points in its organization (Level C): --service adoption; --identifying a referring anesthetist who is on call 24 hours a day; --patient care during the night and weekend; --sharing, drafting and updating written therapeutic protocols; --continuous medical education; --systematic pain assessment; --data collection regarding the efficacy and safety of the implemented protocols; --at least one audit per year. --a preoperative evaluation, including all the necessary information for the management of postoperative analgesia (Level C); --to adequately inform the patient about the risks and benefits of drugs and procedures used to obtain the maximum efficacy from the administered treatments (Level D). We describe pharmacological and loco-regional techniques with special attention to day surgery and difficult populations. Risk management pathways must be the reference for early identification and treatment of adverse events and chronic pain development.

Static forces variation and pressure distribution in laryngoscopy performed by straight and curved blades.

A theoretical analysis of the forces acting on the laryngoscope during the lifting of the epiglottis is carried out by applying the basic principles of statics. The static model of a laryngoscope equipped with a straight and a curved blade and the forces variation, as a function of the introduction angle and of tissue reaction application point, are described. The pharyngeal tissues and epiglottis pressure distribution on the blade is obtained, with a 1mm(2) resolution, by measurements performed in-vitro on a simulation mannequin, using straight and curved blades. The straight blade requires more effort than the curved one to obtain the same visualization of vocal cords, however forces exerted by using a laryngoscope with a curved blade do not vary linearly with the application point of tissue reaction. Average intensity of the tissue reaction has been found in the order of 32+/-11 N. Pressure distribution is maximally concentrated on the tip of curved blades (0.5 MPa on 5mm axial length), whereas it is more dispersed on straight blades (0.2 MPa on 10mm axial length). The inclination of the handle also influences the effort of the operator: for both blades, from 0 rad to 1.57 rad, the lifting force shows a total variation of about 13% of the top value, the transversal forces vary less than 6% of the top value.

[Evaluation of the withdrawal of ACE inhibitors in coronary artery surgery]. / Valutazione della sospensione degli ACE-inibitori in chirurgia cardiaca coronarica.

During cardiac surgery, as a result of surgical aggression, myocardial ischaemia and cardiopulmonary bypass, the renin-angiotensin-aldosterone mechanism is intensely activated. Our aim is to document whether, in the case of patients undergoing chronic treatment with lisinopril, the non-withdrawal of this inhibitor's administration before cardiac surgery and the administering of a last dose on the day of the operation are associated with coronary haemodynamic alterations. A study was made of 18 patients submitted to myocardial revascularization under extracorporeal circulation and distributed in two groups: group A) without ACE inhibitorsplacebo, group B) with ACE inhibitors (Lisinopril). Coronary blood flow (CBF) was determined by inverted thermodilution via Baim's catheter. Coronary and metabolic haemodynamic values were calculated. Lisinopril had no significant influence on the CBF or on the other above-mentioned values. Therefore, it is not necessary to withdraw ACE inhibitors in cardiac surgery interventions.