Pascal Wallot

Videolaryngoscopy with glidescope reduces cervical spine movement in patients with unsecured cervical spine.

BACKGROUND Unconscious patients with severe trauma often require urgent endotracheal intubation. In trauma victims with possible cervical spine injury, any movement of the head and neck should be avoided. STUDY OBJECTIVES We investigated the effect of GlideScope videolaryngoscopy on cervical spine movement compared with conventional laryngoscopy in anesthetized patients with unsecured cervical spines. METHODS Sixty patients scheduled for elective surgery with general anesthesia and without anticipated airway problems were enrolled in the study after ethics committee approval and written informed consent. Intubation was performed with videolaryngoscopy (GlideScope(®), Verathon Inc., Bothell, WA) or conventional laryngoscopy (MacIntosh). Using video motion analysis with a lateral view, the maximum extension angle α was measured with reference to anatomical points (baseline and line drawn from processus mastoideus to os frontale [glabella]). Values were analyzed using Mann Whitney U-tests. RESULTS The deviation of α was a median 11.8° in the videolaryngoscope group and 14.3° in the conventional group (p = 0.045), with a maximum of 19.2° (videolaryngoscopy) vs. 29.3° (conventional). Intubation by physicians with some experience in videolaryngoscopy was associated with a reduced angle deviation (α = 10.3°) compared to inexperienced physicians (12.8°, p = 0.019). Intubation time was a median 24 s (min/max 12/75 s) in the MacIntosh group and 53 s (min/max 28/210 s) in the GlideScope group. In 3 patients randomized to the conventional group in whom conventional intubation failed, intubation could be successfully performed using videolaryngoscopy. CONCLUSION GlideScope videolaryngoscopy reduces movements of the cervical spine in patients with unsecured cervical spines and therefore might reduce the risk of secondary damage during emergency intubation of patients with cervical spine trauma.

Mechanical Ventilation During Cardiopulmonary Resuscitation With Intermittent Positive-pressure Ventilation, Bilevel Ventilation, or Chest Compression Synchronized Ventilation in a Pig Model*

Objective:Mechanical ventilation with an automated ventilator is recommended during cardiopulmonary resuscitation with a secured airway. We investigated the influence of intermittent positive-pressure ventilation, bilevel ventilation, and the novel ventilator mode chest compression synchronized ventilation, a pressure-controlled ventilation triggered by each chest compression, on gas exchange, hemodynamics, and return of spontaneous circulation in a pig model. Design:Animal study. Setting:University laboratory. Subjects:Twenty-four three-month-old female domestic pigs. Interventions:The study was performed on pigs under general anesthesia with endotracheal intubation. Arterial and central venous catheters were inserted and IV rocuronium (1 mg/kg) was injected. After 3 minutes of cardiac arrest (ventricular fibrillation at t = 0 min), animals were randomized into intermittent positive-pressure ventilation (control group), bilevel, or chest compression synchronized ventilation group. Following 10 minute uninterrupted chest compressions and mechanical ventilation, advanced life support was performed (100% O2, up to six defibrillations, vasopressors). Measurements and Main Results:Blood gas samples were drawn at 0, 4 and 13 minutes. At 13 minutes, hemodynamics was analyzed beat-to-beat in the end-inspiratory and end-expiratory cycle comparing the IPPV with the bilevel group and the CCSV group. Data were analyzed with the Mann-Whitney U test. Return of spontaneous circulation was achieved in five of eight (intermittent positive-pressure ventilation), six of eight (bilevel), and four of seven (chest compression synchronized ventilation) pigs. The results of arterial blood gas analyses at t = 4 minutes and t = 13 minutes (torr) were as follows: PaO2 intermittent positive-pressure ventilation, 143 (76/256) and 262 (81/340); bilevel, 261 (109/386) (p = 0.195 vs intermittent positive-pressure ventilation) and 236 (86/364) (p = 0.878 vs intermittent positive-pressure ventilation); and chest compression synchronized ventilation, 598 (471/650) (p < 0.001 vs intermittent positive-pressure ventilation) and 634 (115/693) (p = 0.054 vs intermittent positive-pressure ventilation); PaCO2 intermittent positive-pressure ventilation, 40 (38/43) and 45 (36/52); bilevel, 39 (35/41) (p = 0.574 vs intermittent positive-pressure ventilation) and 46 (42/49) (p = 0.798); and chest compression synchronized ventilation, 28 (27/32) (p = 0.001 vs intermittent positive-pressure ventilation) and 26 (18/29) (p = 0.004); mixed venous pH intermittent positive-pressure ventilation, 7.34 (7.31/7.35) and 7.26 (7.25/7.31); bilevel, 7.35 (7.29/7.37) (p = 0.645 vs intermittent positive-pressure ventilation) and 7.27 (7.17/7.31) (p = 0.645 vs intermittent positive-pressure ventilation); and chest compression synchronized ventilation, 7.34 (7.33/7.39) (p = 0.189 vs intermittent positive-pressure ventilation) and 7.35 (7.34/7.36) (p = 0.006 vs intermittent positive-pressure ventilation). Mean end-inspiratory and end-expiratory arterial pressures at t = 13 minutes (mm Hg) were as follows: intermittent positive-pressure ventilation, 28.0 (25.0/29.6) and 27.9 (24.4/30.0); bilevel, 29.1 (25.6/37.1) (p = 0.574 vs intermittent positive-pressure ventilation) and 28.7 (24.2/36.5) (p = 0.721 vs intermittent positive-pressure ventilation); and chest compression synchronized ventilation, 32.7 (30.4/33.4) (p = 0.021 vs intermittent positive-pressure ventilation) and 27.0 (24.5/27.7) (p = 0.779 vs intermittent positive-pressure ventilation). Conclusions:Both intermittent positive-pressure ventilation and bilevel provided similar oxygenation and ventilation during cardiopulmonary resuscitation. Chest compression synchronized ventilation elicited the highest mean arterial pressure, best oxygenation, and a normal mixed venous pH during cardiopulmonary resuscitation.

Basic life support with four different compression/ventilation ratios in a pig model: The need for ventilation ☆

BACKGROUND During cardiac arrest the paramount goal of basic life support (BLS) is the oxygenation of vital organs. Current recommendations are to combine chest compressions with ventilation in a fixed ratio of 30:2; however the optimum compression/ventilation ratio is still debatable. In our study we compared four different compression/ventilation ratios and documented their effects on the return of spontaneous circulation (ROSC), gas exchange, cerebral tissue oxygenation and haemodynamics in a pig model. METHODS Study was performed on 32 pigs under general anaesthesia with endotracheal intubation. Arterial and central venous lines were inserted. For continuous cerebral tissue oxygenation a Licox PtiO(2) probe was implanted. After 3 min of cardiac arrest (ventricular fibrillation) animals were randomized to a compression/ventilation-ratio 30:2, 100:5, 100:2 or compressions-only. Subsequently 10 min BLS, Advanced Life Support (ALS) was performed (100%O(2), 3 defibrillations, 1mg adrenaline i.v.). Data were analyzed with 2-factorial ANOVA. RESULTS ROSC was achieved in 4/8 (30:2), 5/8 (100:5), 2/8 (100:2) and 0/8 (compr-only) pigs. During BLS, PaCO(2) increased to 55 mm Hg (30:2), 68 mm Hg (100:5; p=0.0001), 66 mm Hg (100:2; p=0.002) and 72 mm Hg (compr-only; p<0.0001). PaO(2) decreased to 58 mmg (30:2), 40 mm Hg (100:5; p=0.15), 43 mm Hg (100:2; p=0.04) and 26 mm Hg (compr-only; p<0.0001). PtiO(2) baseline values were 12.7, 12.0, 11.1 and 10.0 mm Hg and decreased to 8.1 mm Hg (30:2), 4.1 mm Hg (100:5; p=0.08), 4.3 mm Hg (100:2; p=0.04), and 4.5 mm Hg (compr-only; p=0.69). CONCLUSIONS During BLS, a compression/ventilation-ratio of 100:5 seems to be equivalent to 30:2, while ratios of 100:2 or compressions-only detoriate peripheral arterial oxygenation and reduce the chance for ROSC.

High- Versus Low-stimulation Current Threshold for Axillary Plexus Blocks: A Prospective Randomized Triple-blinded Noninferiority Trial in 205 Patients

BACKGROUND:For nerve stimulator-guided regional anesthesia, one has to compromise between a presumed low success rate (using a high-current threshold) and a presumed increased risk of nerve damage (using a low-current threshold). We hypothesized that high-current thresholds in the range of 0.9 to 1.1 mA are not inferior with respect to the procedural and latency times compared with low threshold currents in the range of 0.3 to 0.5 mA for nerve stimulation in brachial plexus blocks. METHODS:Two hundred five patients scheduled for elective surgery were randomized to a low (0.3–0.5 mA, n = 103) or a high (0.9–1.1 mA, n = 102) stimulation current threshold for the axillary plexus block with 40 mL local anesthetic mixture (20 mL, each of prilocaine 1% and ropivacaine 0.75%). The primary end point was the time to complete sensory block. The secondary outcome measures were the time to readiness for surgery (defined as the time from the start of block procedure to complete sensory block) and the block performance time. The noninferiority margin was set at 5 minutes and was evaluated using the two-sided 95% bootstrap-confidence intervals ([CIs] 100,000 replications) for differences in means. RESULTS:The mean times to complete sensory block revealed a significant decrease with the low-current group (17.9 ± 12.1 (mean ± SD) versus 22.8 ± 12.4 minutes; 95% CI, 1.1 to 8.6; p = 0.012). The time to readiness for surgery was 30.3 ± 13.8 minutes in the low-current group and 31.7 ± 12.9 minutes in the high-current group (95% CI, –2.7 to 5.5; p = 0.49). The performance time was significantly shorter in the high-current threshold group (9.5 ± 4.7 versus 11.9 ± 5.7 minutes; 95% CI, –4 to 1.1; p = 0.001). CONCLUSION:Noninferiority for the high-current threshold technique could neither be confirmed for the primary end point nor for secondary end points. However, we consider a difference in mean times of approximately 8.5 minutes to achieve readiness for surgery acceptable for clinical practice.

Chest Compression Synchronized Ventilation versus Intermitted Positive Pressure Ventilation during Cardiopulmonary Resuscitation in a Pig Model

Background Guidelines recommend mechanical ventilation with Intermitted Positive Pressure Ventilation (IPPV) during resuscitation. The influence of the novel ventilator mode Chest Compression Synchronized Ventilation (CCSV) on gas exchange and arterial blood pressure compared with IPPV was investigated in a pig model. Methods In 12 pigs (general anaesthesia/intubation) ventricular fibrillation was induced and continuous chest compressions were started after 3min. Pigs were mechanically ventilated in a cross-over setting with 5 ventilation periods of 4min each: Ventilation modes were during the first and last period IPPV (100% O2, tidalvolumes = 7ml/kgKG, respiratoryrate = 10/min), during the 2nd, 3rd and 4th period CCSV (100% O2), a pressure-controlled and with each chest compression synchronized breathing pattern with three different presets in randomized order. Presets: CCSVA: Pinsp = 60mbar, inspiratorytime = 205ms; CCSVB: Pinsp = 60mbar, inspiratorytime = 265ms; CCSVC: Pinsp = 45mbar, inspiratorytime = 265ms. Blood gas samples were drawn for each period, mean arterial (MAP) and centralvenous (CVP) blood pressures were continuously recorded. Results as median (25%/75%percentiles). Results Ventilation with each CCSV mode resulted in higher PaO2 than IPPV: PaO2: IPPVfirst: 19.6(13.9/36.2)kPa, IPPVlast: 22.7(5.4/36.9)kPa (p = 0.77 vs IPPVfirst), CCSVA: 48.9(29.0/58.2)kPa (p = 0.028 vs IPPVfirst, p = 0.0001 vs IPPVlast), CCSVB: 54.0 (43.8/64.1) (p = 0.001 vs IPPVfirst, p = 0.0001 vs IPPVlast), CCSVC: 46.0 (20.2/58.4) (p = 0.006 vs IPPVfirst, p = 0.0001 vs IPPVlast). Both the MAP and the difference MAP-CVP did not decrease during twelve minutes CPR with all three presets of CCSV and were higher than the pressures of the last IPPV period. Conclusions All patterns of CCSV lead to a higher PaO2 and avoid an arterial blood pressure drop during resuscitation compared to IPPV in this pig model of cardiac arrest.

Separation of stimulating catheters for continuous peripheral regional anesthesia during their removal – two case reports and a critical appraisal of the use of steel-coil containing stimulating catheters

Purpose Stimulating catheters are widely used for continuous peripheral nerve block techniques in regional anesthesia. The incidence of reported complications is somewhat similar to that for non-stimulating catheters. However, as many stimulating catheters contain a coiled steel wire for optimal stimulation, they may cause specific complications. Clinical features In this report, we present two cases of complicated removals of stimulating catheters. During both removals, a part of the metal wire was left “decoiled” next to the supraclavicular and interscalene plexus, respectively. The strategies used to determine steel wire localization and a description of the successful removal of these steel wires are included in this report. Conclusion Catheter separation and problems with residual metal wire components of stimulating catheters seem to be a rare but specific problem during removal. Anesthesiologists should strictly avoid catheter shearing during insertion, adhere to the manufacturer’s instructions, and take care during catheter removal. Manufacturers should focus on technical solutions to avoid rare but relevant complications such as catheter tip decoiling and separation of stimulating catheters during removal.

AP015 Chest compression synchronized ventilation during CPR: Technical solution and flow-volume curves of a novel ventilator mode

Mechanical ventilation with an automated ventilator is recommended during CPR with secured airway 1 . We developed and investigated the novel ventilator mode Chest Compression Synchronized Ventilation (CCSV), a pressure controlled ventilation triggered by each chest compression. The new ventilator mode and trigger technology are described and the resulting flow-volume curves were investigated in a pig model.