Investigating the functional neuroanatomy of concrete and abstract word processing through direct electric stimulation (DES) during awake surgery.

Neuropsychological, neuroimaging and electrophysiological studies demonstrate that abstract and concrete word processing relies not only on the activity of a common bilateral network but also on dedicated networks. The neuropsychological literature has shown that a selective sparing of abstract relative to concrete words can be documented in lesions of the left anterior temporal regions. We investigated concrete and abstract word processing in 10 patients undergoing direct electrical stimulation (DES) for brain mapping during awake surgery in the left hemisphere. A lexical decision and a concreteness judgment task were added to the neuropsychological assessment during intra-operative monitoring. On the concreteness judgment, DES delivered over the inferior frontal gyrus significantly decreased abstract word accuracy while accuracy for concrete words decreased when the anterior temporal cortex was stimulated. These results are consistent with a lexical-semantic model that distinguishes between concrete and abstract words related to different neural substrates in the left hemisphere.

Defining and developing expertise in tracheal intubation using a GlideScope(®) for anaesthetists with expertise in Macintosh direct laryngoscopy: an in-vivo longitudinal study.

Although videolaryngoscopy can provide excellent views of the laryngeal structures as both the primary method of tracheal intubation and as a rescue technique for difficult direct laryngoscopy, the existing literature is inadequate to define expertise or even competence. We observed the performance of nine trainees during 890 intubations, with an additional 72 intubations performed by expert anaesthetists used as a control group. Univariate and multivariate mixed-effects logistic regression models were applied to detect potential predictors of successful intubation and define the number of intubations necessary for a trainee to achieve expertise (> 90% probability of optimal performance). Optimal performance was predicted by single laryngoscope insertion (p < 0.001) and a Cormack and Lehane grade-1 view (p < 0.001), and not by normal lifting force applied to the device (p = 0.15), with expertise reached after 76 attempts. These results indicate that expertise in videolaryngoscopy requires prolonged training and practice.

Upper limb muscular activity and perceived workload during laryngoscopy: comparison of Glidescope(R) and Macintosh laryngoscopy in manikin: an observational study.

BACKGROUND: The interaction between operators and their working environment during laryngoscopy is poorly understood. Numerous studies have focused on the forces applied to the patient's airway during laryngoscopy, but only a few authors have addressed operator muscle activity and workload. We tested whether different devices (Glidescope(®) and Macintosh) use different muscles and how these differences affect the perceived workload. METHODS: Ten staff anaesthetists performed three intubations with each device on a manikin. Surface electromyography was recorded for eight single muscles of the left upper limb. The NASA Task Load Index (TLX) was administered after each experimental session to evaluate perceived workload. RESULTS: A consistent reduction in muscular activation occurred with Glidescope(®) compared with Macintosh for all muscles tested (mean effect size d=3.28), and significant differences for the upper trapezius (P=0.002), anterior deltoid (P=0.001), posterior deltoid (P=0.000), and brachioradialis (P=0.001) were observed. The overall NASA-TLX workload score was significantly lower for Glidescope(®) than for Macintosh (P=0.006), and the factors of physical demand (P=0.008) and effort (P=0.006) decreased significantly. CONCLUSIONS: Greater muscular activity and workload were observed with the Macintosh laryngoscope. Augmented vision and related postural adjustments related to using the Glidescope(®) may reduce activation of the operator's muscles and task workload.

A new difficult airway management algorithm based upon the El Ganzouri Risk Index and GlideScope® videolaryngoscope. A new look for intubation?

BACKGROUND: An El Ganzouri risk index test (EGRI) score of seven and the ability to achieve difficult laryngeal exposure with the GlideScope® may represent a highly predictive decisional threshold. Hence, we hypothesized that a new difficult airways algorithm that is EGRI- and GlideScope®-based may enable tracheal intubation in every patient. METHODS: Thirteen staff practitioners trained in videolaryngoscopic intubation followed the algorithm from 2008 through 2010. Elective and emergency neurosurgical patients assessed as having an EGRI score of seven and higher underwent flexible fiberoptic bronchoscopy (FFB) intubation while conscious. Those with a score of six and lower were intubated with the GlideScope®, excluding patients with morbid obesity or pharyngo-laryngeal or neck tumors. A decision to perform alternative procedures, difficult laryngeal exposure [Cormack and Lehane (CL) grades III-IV], difficult ventilation and failure to intubate were recorded. RESULTS: The decisional rule was applied in 6,276 patients and resulted in six FFB intubations in conscious patients. The overall incidence of CL grade III-IV views was 0.2%. Difficult videolaryngoscopy was found in 14 patients (0.14%) with a score of 6 and lower. Post-hoc examinations of FFB intubations revealed five difficult laryngeal exposures. The positive predictive value was 85.7%, while the negative predictive value was 99.9%. The incidence of difficult ventilation and difficult laryngeal exposure was 0.03%. Two patients with neck tumors were assigned to alternative procedures. CONCLUSION: Adherence to the decisional process of the algorithm and to GlideScope® videolaryngoscopy achieved successful tracheal intubation in our cohort of patients.

Safety and efficacy of ultrasound assistance during internal jugular vein cannulation in neurosurgical infants.

OBJECTIVE: Ultrasound guidance (USG) for internal jugular cannulation is the best solution in difficult settings where paediatric patients are involved. This is an outcome study on efficacy and complications of the USG for the internal jugular vein (IJV) cannulation in neurosurgical infants as well as an ultrasound study of anatomical findings of the IJVs in infants. DESIGN AND SETTINGS: A prospective study conducted in two Academic Neurosurgical hospitals. PARTICIPANTS: In 191 babies (body weight <15 kg), anatomical findings were studied. We performed CVC echo guided placement in 135/191 infants (weighting <10 kg). RESULTS: After a brief training period, both institutions adopted a common protocol and USG device. We obtained successful cannulation in all patients. Carotid puncture (1.5%) was the only main complication registered and minor complications were poor. Time required for cannulation was 12.5 +/- 5.7 min. Anatomical findings (in 191 patients) were IJV laterality in 34.6% cases, IJV antero-lateral in 59.7% and anterior in 5.7%. A linear relation was found between weight and internal jugular vein diameter even if R(2) = 0.43 and the model cannot be used to predict the exact size of the vein. In 62/135 babies weighting <10 kg, anatomical measurements were done in supine and Trendelemburg position. Trendelemburg position increases significantly (P < 0.001) IJV diameter, but not IJV depth. CONCLUSIONS: We considered ultrasound guidance as the first choice in infants because it can enhance IJV cannulation success, safety, and allows one to measure relationships and diameter of the IJV and optimise the central line positioning.

Predictive value of the El-Ganzouri multivariate risk index for difficult tracheal intubation: a comparison of Glidescope videolaryngoscopy and conventional Macintosh laryngoscopy.

BACKGROUND: The predictive value of the El-Ganzouri risk index (EGRI) for difficult intubation has been evaluated using Macintosh laryngoscopy as reference standard. The Glidescope videolaryngoscope provides improved visualization of the glottis. We studied the predictive value of the EGRI using videolaryngoscopy as reference standard. METHODS: Data from two subsequent groups of patients, intubated with Macintosh laryngoscopy (ML, n = 994) and videolaryngoscopy (VL, n = 843), were retrospectively analysed. The EGRI was taken as index test. The two types of laryngoscopy were adopted as reference for the presence of Cormack and Lehane grading III-IV. For both groups, sensitivity, specificity, and positive and negative post-test probabilities (PTP) were calculated for thresholds on the EGRI scale. Receiver operating characteristic curves and corresponding areas (AUC) were obtained. RESULTS: Sensitivity and specificity were 69.7% and 66.3% at the cut-off value of 2 in the ML group, and 93.3% and 76.6% at the cut-off value of 3 in the VL group. Corresponding positive and negative PTP were 12.81% and 3.15% in the ML group, and 6.73% and 0.16% in the VL group. At the threshold of 4, positive and negative PTP were 31.34% and 4.85% in the ML group. At the threshold of 7, positive and negative PTP were 85.71% and 1.08% in the VL group. The AUC was 0.74 in the ML group and 0.91 in the VL group. CONCLUSIONS: The predictive value of the EGRI may have been underestimated due to limited accuracy of Macintosh laryngoscopy. Using videolaryngoscopy, the EGRI might be reconsidered as a decisional tool.

An outcome study on complications using routine ultrasound assistance for internal jugular vein cannulation.

BACKGROUND: Ultrasound guidance for central venous cannulation is advised by recent guidelines, but is not being applied in everyday practice. The purpose of this study was to determine the reduction in complications when applying an ultrasound locating device for internal jugular vein catheterization. METHODS: An observational study was conducted from November 2004 to October 2005 in a tertiary neurosurgical hospital on 300 patients undergoing internal jugular vein cannulation using an ultrasound technique. Patients were not randomized and operators were trained using theoretical and practical courses. Prior to the study, the investigators, who were consultant anaesthesiologists, had to perform at least 20 successful supervised cannulations. RESULTS: Cannulation was successful in all cases. The incidence of arterial puncture was 2.7%, and multiple venous punctures represented the main minor complication (14%). Bivariate analysis of the overall complications revealed no significant correlation with age group, American Society of Anesthesiologists' (ASA) classification, body mass index, or position and diameter of the vein. CONCLUSIONS: Ultrasound cannulation of the internal jugular vein minimized complications. These could be avoided when new ultrasound probes and specific needles are introduced.

Early experience with remote pressure sensor respiratory plethysmography monitoring sedation in the MR scanner.

BACKGROUND AND OBJECTIVE: The importance of monitoring the breathing pattern during sedation of children undergoing magnetic resonance scans is indicated in guidelines, but no appropriate magnetic resonance-compatible devices are available. We report preliminary findings from a technique referred to as remote pressure sensor respiratory plethysmography. METHODS: A data acquisition system was developed, enabling measurement of respiratory rate, plethysmogram amplitude, proportion of inspiratory time over cycle time, thoraco-abdominal phase shift and sigh rate. Correlation between plethysmogram amplitude and tidal volume was investigated on adult volunteers. Twenty-seven children undergoing sedation were monitored with remote pressure sensor respiratory plethysmography, in addition to SPO2 and PetCO2. Differences in monitoring parameters were searched for among three groups: patients who received chloral hydrate only (chloral succeeded, CS group), those who received a supplementation of sodium thiopental (chloral failed, CF group), and those who were sedated with sodium thiopental directly (no chloral, NC group). Correlations were searched for among monitoring parameters, and with total dose of thiopental. The long-term behaviour of respiratory rate, proportion of inspiratory time over cycle time and phase shift was studied. RESULTS: Plethysmogram amplitude was found to correlate linearly with tidal volume (r>0.92), with a slope varying up to 22%. While 11% of patients did not tolerate the capnometric probe and readings were discontinuous in 26%, all of them tolerated remote pressure sensor respiratory plethysmography belts. Sighs and non-respiratory movements of the torso could be distinguished on remote pressure sensor respiratory plethysmography waveforms. No significant inter-group differences were found in PetCO2, SPO2, respiratory rate and phase shift. Proportion of inspiratory time over cycle time was higher in the NC group when compared to the CS group (0.497+/-0.03 vs. 0.463+/-0.008; P=0.02), the CF group being characterized by intermediate values (0.480+/-0.008); when compared to the CS group, sigh rate was lower in the CF group (0.04+/-0.04 vs. 0.14+/-0.08; P=0.04) and in the NC group (0.06+/-0.05 vs. 0.14+/-0.08, P=0.03). A positive correlation was found between total dose of thiopental and proportion of inspiratory time over cycle time, with r=0.4 and P=0.04. A large baseline variability in phase shift was found. No long-term trends predictive of patient movement could be identified. CONCLUSIONS: Breathing pattern monitoring is feasible through pneumatic devices, which are well tolerated. The resulting correlation with changes in tidal volume can be better when compared to visual inspection. Proportion of inspiratory time over cycle time and sigh rate convey information related to the state of the sedated patient. These results are not specific to the technology employed, and large-scale studies on the clinical usefulness of breathing pattern monitoring are motivated.

[Home care to tracheotomized patients: evaluation of the customer satisfaction in the city of Milano]. / L'assistenza domiciliare al paziente tracheotomizzato: esperienza di valutazione del livello di soddisfazione nella città di Milano.

Home care for tracheotomised patients appears to be a relevant problem in health care management. In order to allow patients to be cured at home high care standard have to be assured, and a multidisciplinary level of assistance implemented for preventing complications like respiratory infections. This study was conducted in order to assess patients and/or care givers level of satisfaction through a telephone survey. It was aimed at allowing those responsible for the given services to assess whether improvements can be achieved particularly in so far as the actual clinical and managerial pathway is concerned.

The tension-time index of the diaphragm revisited in quadriplegic patients with diaphragm pacing.

The fatigue threshold of the human diaphragm, index of its endurance and fatigability, corresponds, during spontaneous breathing, to a tension-time index (TTdi = Pdi/Pdimax x T1/Ttot (i.e., the inspiratory time over the total breath duration) of 0.15 to 0.18. We studied three quadriplegic patients with diaphragm pacing in order to reassess this threshold in patients in whom the contribution of the other respiratory muscles is lacking. Transdiaphragmatic pressure (Pdi) was obtained from the difference between gastric (Pga) and esophageal (Pes) pressures while the electromyograms (EMG) of both hemidiaphragms were recorded with surface electrodes. Four runs at different TTdi were performed on different days in each subject, varying either the Pdi developed per breath, changing the frequency of stimulation, or the T1/Ttot. The time of fatigue was defined when Pdi decreased during the trials by 35% from baseline. No evidence of transmission fatigue (i.e., decline in action potential amplitude) was observed. The TTdi at which fatigue occurred in all the quadriplegic patients was around 0.10 to 0.12, well below the values previously described. After fatigue had occurred, the force recovery during the force-frequency curve was not complete after 2 h at low frequencies, whereas at high frequencies it was fully complete at 30 min. We conclude that when respiration is accomplished only by the diaphragm, without the contribution of the other respiratory muscles, the fatigue threshold is lower than previously reported.

Influences of neural mechanisms on heart period and arterial pressure variabilities in quadriplegic patients.

The heart period (R-R) variability power spectrum presents two components, at low (LF; approximately 0.10 Hz) and high (approximately 0.25 Hz) frequencies, whose reciprocal powers appear to furnish an index of sympathovagal interaction modulating heart rate. In addition, the LF component of the systolic arterial pressure variability spectrum furnishes a marker of sympathetic modulation of vasomotor activity. The contribution of spinal and supraspinal neural circuits to the genesis of these rhythmic oscillatory components remains largely unsettled. Therefore we performed spectral analysis of R-R and systolic arterial pressure variabilities in 15 chronic neurologically complete quadriplegic patients (QP) and in 15 control subjects during resting conditions, controlled respiration, and head-up tilt. At rest, in seven QP the LF component was undetectable in both cardiovascular variability spectra; in two QP this component was present only in R-R variability spectrum, whereas the remaining six showed a significantly reduced LF in both signals. In QP, the LF component, when present, underwent paradoxical changes with respect to controls, decreasing during tilt and increasing during controlled respiration. In five QP in whom the recording session was repeated after 6 mo, a significant increase in LF was observed in both variability spectra. These data confirm the finding that a disconnection of sympathetic outflow from supraspinal centers can cause the disappearance of the LF spectral component. However, LF presence in some QP supports the hypothesis of a spinal rhythmicity likely to be modulated by the afferent sympathetic activity.