[Recommendations of the new S1 guidelines on airway management]. / Empfehlungen zur neuen S1-Leitlinie Atemwegsmanagement.

The German guidelines for airway management aim to optimize the care of patients undergoing anesthesia or intensive care. The preanesthesia evaluation is an important component for detection of anatomical and physiological indications for difficult mask ventilation and intubation. If predictors for a difficult or impossible mask ventilation and/or endotracheal intubation are present the airway should be secured while maintaining spontaneous breathing. In an unexpectedly difficult intubation, attempts to secure the airway should be limited to two with each method used. A video laryngoscope is recommended after an unsuccessful direct laryngoscopy. Therefore, a video laryngoscope should be available at every anesthesiology workspace throughout the hospital. Securing the airway should primarily be performed with a video laryngoscope in critically ill patients and patients at risk of pulmonary aspiration. Experienced personnel should perform or supervise airway management in the intensive care unit.

Videolaryngoscopy for Physician-Based, Prehospital Emergency Intubation: A Prospective, Randomized, Multicenter Comparison of Different Blade Types Using A.P. Advance, C-MAC System, and KingVision.

BACKGROUND: Videolaryngoscopy is a valuable technique for endotracheal intubation. When used in the perioperative period, different videolaryngoscopes vary both in terms of technical use and intubation success rates. However, in the prehospital environment, the relative performance of different videolaryngoscopic systems is less well studied. METHODS: We conducted this prospective, randomized, multicenter study at 4 German prehospital emergency medicine centers. One hundred sixty-eight adult patients requiring prehospital emergency intubation were treated by an emergency physician and randomized to 1 of 3 portable videolaryngoscopes (A.P. Advance, C-MAC PM, and channeled blade KingVision) with different blade types. The primary outcome variable was overall intubation success and secondary outcomes included first-attempt intubation success, glottis visualization, and difficulty with handling the devices. P values for pairwise comparisons are corrected by the Bonferroni method for 3 tests (P[BF]). All presented P values are adjusted for center. RESULTS: Glottis visualization was comparable with all 3 devices. Overall intubation success for A.P. Advance, C-MAC, and KingVision was 96%, 97%, and 61%, respectively (overall: P < .001, A.P. Advance versus C-MAC: odds ratio [OR], 0.97, 95% confidence interval [CI], 0.13-7.42, P[BF] > 0.99; A.P. Advance versus KingVision: OR, 0.043, 95% CI, 0.0088-0.21, P[BF] < 0.001; C-MAC versus KingVision: OR, 0.043, 95% CI, 0.0088-0.21, P[BF] < 0.001). Intubation success on the first attempt with A.P. Advance, C-MAC, and KingVision was 86%, 85%, and 48%, respectively (overall: P < .001, A.P. Advance versus C-MAC: OR, 0.89, 95% CI, 0.31-2.53, P[BF] > 0.99; A.P. Advance versus KingVision: OR, 0.24, 95% CI, 0.055-0.38, P[BF] = 0.0054; C-MAC versus KingVision: OR, 0.21, 95% CI, 0.043-.34, P[BF] < 0.003). Direct laryngoscopy for successful intubation with the videolaryngoscopic device was necessary with the A.P. Advance in 5 patients, and with the C-MAC in 4 patients. In the KingVision group, 21 patients were intubated with an alternative device. CONCLUSIONS: During prehospital emergency endotracheal intubation performed by emergency physicians, success rates of 3 commercially available videolaryngoscopes A.P. Advance, C-MAC PM, and KingVision varied markedly. We also found that although any of the videolaryngoscopes provided an adequate view, actual intubation was more difficult with the channeled blade KingVision.

Effect of ischemic and pharmacological preconditioning of lower limb muscle tissue on tissue oxygenation measured by near-infrared spectroscopy--a pilot study.

BACKGROUND: Ischemic or volatile anesthetic preconditioning is defined as tissue protection from impending ischemic cell damage by repetitive short periods of tissue exposure to ischemia or volatile anesthetics. Objective of this study was to elucidate, if ischemic preconditioning and pharmacological preconditioning with sevoflurane have effects on muscle tissue oxygen saturation in patients undergoing surgical revascularization of the lower limb. METHODS: In this prospective randomized pilot study ischemic and pharmacological (sevoflurane) preconditioning was performed in 40 patients with lower limb arterial occlusive disease undergoing surgical revascularization. Sevoflurane preconditioning was performed in one group (N = 20) by repetitive application of sevoflurane for six minutes interspersed by six minutes of washout. Thereafter, ischemic preconditioning was performed in all patients (N = 40) by repetitive clamping of the femoral artery for six minutes interspersed by six minutes of reperfusion. The effect of both procedures on leg muscle tissue oxygen saturation (rSO2) was measured by near-infrared spectroscopy during both procedures and during surgery and reperfusion (INVOS® 5100C Oxymeter with Small Adult SomaSensor® SAFB-SM, Somanetics, Troy, Michigan, USA). RESULTS: Repetitive clamping and reperfusion of the femoral artery resulted in significant cyclic decrease and increase of muscle rSO2 (p < 0.0001). Pharmacological preconditioning with sevoflurane resulted in a faster and higher increase of rSO2 during postoperative reperfusion (Maximal 111% baseline ± 20 versus 103% baseline ± 14, p = 0.008) consistent with an additional effect of pharmacological preconditioning on leg perfusion. CONCLUSIONS: Ischemic preconditioning of lower limb muscle tissue and pharmacological preconditioning with sevoflurane have an effect on tissue oxygenation in patients with lower limb occlusive arterial disease. TRIAL REGISTRATION: The trial has been registrated at http://www.ClinicalTrial.gov, TRIAL NUMBER: NCT02038062 at 14 January 2014.

Airway management disasters in the ICU--lessons learned?

The C-MAC video laryngoscope substantially reduced poor glottic views and increased intubation success in ICU patients with at least one predictor for difficult intubation. However, all video-assisted and optical intubation devices have different view angles, thus producing different images with particular distortion, and even experts in 'old-fashioned' airway management need a substantial level of training with a certain device before using it safely and successfully in critical situations and patients. Video laryngoscopes, regardless of a particular brand or device, cannot be used intuitively - they require expert skills and routines to be turned into a life-saving airway management tool.

[Airwaymanagement: video-assisted airway management]. / Atemwegsmanagement - Videoassistierte Verfahren.

Endotracheal intubation remains the "goldstandard" in airway management. If with use of conventional techniques intubation of the patient fails, or if an anticipated difficult airway is present, video-assisted techniques may help to increase intubation success. Video-assisted techniques give the possibility to indirectly visualise the laryngeal structures with fibreoptical or camerachip-technique, and to display the videopicture on an external or integrated monitor. For the anticipated difficult airway, awake flexible fibreoptical intubation still is the first choice. However, if Oxygenation and Ventilation can be established with bag-mask ventilation or supraglottic airways, the use of an endoscopic optical stylet or a videolaryngoscope may be alternatives. If the algorithm for the unanticipated difficult airway can be safely administered, the latter techniques may also be used as emergency intubation devices.

A randomised, controlled crossover comparison of the C-MAC videolaryngoscope with direct laryngoscopy in 150 patients during routine induction of anaesthesia.

BACKGROUND: The C-MAC® (Karl Storz, Tuttlingen, Germany) has recently been introduced as a new device for videolaryngoscopy guided intubation. The purpose of the present study was to compare for the first time the C-MAC with conventional direct laryngoscopy in 150 patients during routine induction of anaesthesia. METHODS: After approval of the institutional review board and written informed consent, 150 patients (ASA I-III) with general anaesthesia were enrolled. Computer-based open crossover randomisation was used to determine the sequence of the three laryngoscopies: Conventional direct laryngoscopy (HEINE Macintosh classic, Herrsching, Germany; blade sizes 3 or 4; DL group), C-MAC size 3 (C-MAC3 group) and C-MAC size 4 (C-MAC4 group) videolaryngoscopy, respectively. After 50 patients, laryngoscopy technique in the C-MAC4 group was changed to the straight blade technique described by Miller (C-MAC4/SBT). RESULTS: Including all 150 patients (70 male, aged (median [range]) 53 [20-82] years, 80 [48-179] kg), there was no difference of glottic view between DL, C-MAC3, C-MAC4, and C-MAC4/SBT groups; however, worst glottic view (C/L 4) was only seen with DL, but not with C-MAC videolaryngoscopy. In the subgroup of patients that had suboptimal glottic view with DL (C/L≥2a; n = 24), glottic view was improved in the C-MAC4/SBT group; C/L class improved by three classes in 5 patients, by two classes in 2 patients, by one class in 8 patients, remained unchanged in 8 patients, or decreased by two classes in 1 patient. The median (range) time taken for tracheal intubation in the DL, C-MAC3, C-MAC4 and C-MAC4/SBT groups was 8 sec (2-91 sec; n = 44), 10 sec (2-60 sec; n = 37), 8 sec (5-80 sec; n = 18) and 12 sec (2-70 sec; n = 51), respectively. CONCLUSIONS: Combining the benefits of conventional direct laryngoscopy and videolaryngoscopy in one device, the C-MAC may serve as a standard intubation device for both routine airway management and educational purposes. However, in patients with suboptimal glottic view (C/L≥2a), the C-MAC size 4 with straight blade technique may reduce the number of C/L 3 or C/L 4 views, and therefore facilitate intubation. Further studies on patients with difficult airway should be performed to confirm these findings.

The C-MAC videolaryngoscope for prehospital emergency intubation: a prospective, multicentre, observational study.

BACKGROUND: In this preliminary prospective observational study at four physician-led air rescue centres, the efficacy of the C-MAC (Karl Storz, Tuttlingen, Germany), a new portable videolaryngoscope, was evaluated during prehospital emergency endotracheal intubations. METHODS: 80 consecutive patients requiring prehospital emergency intubation, treated by a physician introduced in the use of the C-MAC were enrolled in this study. RESULTS: Indication for prehospital intubation was trauma in 45 cases (including maxillo-facial trauma in 10 cases), cardiopulmonary resuscitation in 14 cases, and unconsciousness of neurological aetiology and cardiogenic dyspnoea in 21 cases. Forty-nine patients were intubated with a C-MAC blade size 3, and 31 with a C-MAC blade size 4. Median time to successful intubation was 20 (min-max: 5-300) seconds; 63 patients were intubated on the first attempt, 13 on the second and four after more than two attempts. A Cormack-Lehane class 1 view of the glottis was seen in 46 patients, class 2a view in 21, class 2b in eight, class 3 in three and class 4 in two. Six patients could not be intubated with the videolaryngoscopic view, but were successfully intubated at the same attempt using the C-MAC with the direct laryngoscopic view. CONCLUSION: The C-MAC videolaryngoscope was suitable for prehospital emergency endotracheal intubations with complicated airway conditions, such as maxillo-facial trauma. The option to perform direct laryngoscopy and videolaryngoscopy with the same device appears to be exceptionally important in the prehospital setting.

First clinical evaluation of the C-MAC D-Blade videolaryngoscope during routine and difficult intubation.

In the present preliminary study we evaluated the C-MAC® D-Blade (Karl Storz, Tuttlingen, Germany), a new videolaryngoscopic C-MAC blade for difficult intubation, during both routine and difficult intubations. First, both the conventional direct laryngoscopy and the D-Blade were used in 15 consecutive patients with normal airways during routine induction of anesthesia. Second, the D-Blade was used as a rescue device in 20 of 300 (6.7%) consecutive patients, when conventional direct laryngoscopy failed. In the 15 patients during routine induction of anesthesia, with direct laryngoscopy, a Cormack-Lehane (C/L) grade 1 and grade 2a view was seen in 7 and 8 patients, respectively. It was possible to insert the D-Blade and to get a video view of the glottis on the first attempt in all patients; with the D-Blade, all 15 patients had a C/L 1 view. The time to successful intubation with the D-Blade was 15 (8-26) seconds (median (range)). In the 20 patients, in whom unexpected difficulty with direct laryngoscopy was observed, C/L grades 3 and 4 were present in 15 and 5 patients, respectively. With the use of the D-Blade, indirect C/L video view improved to C/L class 1 in 15 patients, and to 2a in 5 patients, respectively. The time from touching the laryngoscope to optimal laryngoscopic view was 11 (5-45) seconds and for successful intubation 17 (3-80) seconds. In all 35 patients, with the D-Blade no direct view of the glottis was possible and subsequently a semiflexible tube guide was required.

Effects of cerebral hypoperfusion on bispectral index: a randomised, controlled animal experiment during haemorrhagic shock.

BACKGROUND: The aim of this porcine haemorrhagic shock model was to investigate the changes of bispectral index (BIS) after slow and fast recovery of cerebral perfusion, and its correlation with plasma propofol concentrations. METHODS: After Animal Investigational Committee approval, 16 pigs during propofol anaesthesia underwent a liver trauma with severe hypotension, and were randomly assigned to receive therapy for either slow recovery (fluid resuscitation; slow group; n=8) or fast recovery of cerebral perfusion (vasopressor combined with hypertonic-saline-starch; fast group; n=8), respectively. Cerebral perfusion pressure (CPP=MAP-ICP), cerebral tissue oxygenation index (TOI), BIS, and plasma concentrations of propofol and haemoglobin were measured at baseline (Pre-shock), haemodynamic decompensation (Shock), and 5 (Therapy) and 30 min (End) after therapy, respectively. RESULTS: CPP, TOI, and BIS decreased significantly during shock (pre-shock vs. shock, fast: CPP: 65+/-14 vs. 15+/-4 mmHg; TOI: 64+/-6 vs. 47+/-7%; BIS 60+/-5 vs. 9+/-10; slow: CPP: 60+/-12 vs. 13+/-7 mmHg; TOI: 68+/-7 vs. 49+/-7%; BIS 63+/-5 vs. 13+/-12; P<0.05). In the fast group, CPP, TOI, and BIS increased after therapy compared to the slow group (Therapy, fast: CPP: 47+/-15 mmHg, TOI: 61+/-7%, BIS: 47+/-21; slow: CPP: 18+/-9 mmHg, TOI: 51+/-5%, BIS: 21+/-19; P<0.05). Propofol and haemoglobin concentrations were comparable between groups throughout the resuscitation phase. CONCLUSIONS: In a haemorrhagic shock scenario, therapies with different impact on cerebral perfusion resulted in differing changes of BIS values, while plasma propofol and haemoglobin concentrations were comparable during the resuscitation phase; this suggests that BIS may also have reflected changes of cerebral perfusion.

Laryngeal tube S II, laryngeal tube S disposable, Fastrach laryngeal mask and Fastrach laryngeal mask disposable during elective surgery: a randomized controlled comparison between reusable and disposable supraglottic airway devices.

BACKGROUND AND OBJECTIVE: Analogue disposable devices of the laryngeal tube S II (LTS II) and the Fastrach laryngeal intubation mask (ILMA, Fastrach), namely the laryngeal tube disposable (LTS-D) and the Fastrach laryngeal intubation mask disposable (Fastrach-D), have recently been introduced. The purpose of this study was to compare each reusable device with the corresponding disposable one, during routine surgery. METHODS: After informed consent, 120 American Society of Anesthesiologists I-III patients scheduled for routine minor surgery were randomly allocated to the LTS II (n = 30), the LTS-D (n = 30), the Fastrach (n = 30) and the Fastrach-D (n = 30) groups, respectively. Overall insertion success rates, time to first sufficient ventilation (V(e)t > or = 200 ml), resulting airway leak pressures (ALPs), subjective assessment of handling as well as patient comfort were determined. RESULTS: Insertion success rates of the LTS II, LTS-D, Fastrach and Fastrach-D were 30/30, 29/30, 30/30 and 30/30, respectively. Time to successful insertion in the LTS II vs. the LTS-D group, as well as in the Fastrach vs. the Fastrach-D group, showed significant differences [median (min-max) s: 38 (13-187), 23 (9-108), P < 0,05; 27.5 (6-110), 16 (8-82), P < 0.05]. The highest ALP could be observed in the LTS-D group [median (min-max): 40 (16-40), P < 0.001 vs. all other devices] and the lowest ALP in the Fastrach-D group [median (min-max): 24.5 (12-40)]. ALP did not differ significantly in any group during variation of cuff volume by +/-20 ml. Subjective assessment of handling was significantly (P < 0.001) better in the LTS-D group than in the LTS II, Fastrach and Fastrach-D groups. CONCLUSION: LTS II, LTS-D, Fastrach and Fastrach-D were all suitable for routine airway management. The LTS-D showed the best properties in terms of airway sealing and handling.

The C-MAC videolaryngoscope: first experiences with a new device for videolaryngoscopy-guided intubation.

We studied the efficacy of the C-MAC (Karl Storz, Tuttlingen, Germany), a new portable videolaryngoscope, in 60 patients during routine induction of anesthesia. It was possible to insert the blade (Size 3) of the C-MAC and to get a view of the glottis on the first attempt in all patients. Tracheal intubation also was successful in all 60 patients; 52 patients were intubated on the first attempt, 6 on the second, and 2 on the third. In 8 patients (13%), a gum elastic bougie guide was required. A Cormack-Lehane Class 1 view of the glottis was seen in 30 patients without external manipulation and in 45 with external manipulation, Class 2a view in 22 without and 12 with, Class 2b in 2 without, and Class 3 in 2 without manipulation. The median time taken for tracheal intubation was 16 s (range, 6-58 s). In addition, we describe our experience with 3 patients in whom we had unexpected difficulty with direct laryngoscopy with a conventional Macintosh laryngoscope (Cormack-Lehane Class 3, 4, and 4, respectively). These patients' airways were successfully managed on the first attempt when using the C-MAC Size 4 blade (improvement to Cormack-Lehane Class 1, 2a, and 2b, respectively) in a modified manner by uploading the epiglottis, which is known as "straight blade technique."

Cerebral metabolism during deep hypothermic circulatory arrest vs moderate hypothermic selective cerebral perfusion in a piglet model: a microdialysis study.

BACKGROUND: Few data exist regarding antegrade selective cerebral perfusion (ASCP) and its application in newborn and juvenile patients. Clinical data suggest ASCP alone to be superior to deep hypothermic circulatory arrest (DHCA); however, the effects of moderate hypothermia during ASCP on cerebral metabolism in this patient population are still unclear. METHODS: After obtaining the approval from animal investigation committee, 16 piglets were randomly assigned to circulatory arrest combined with either ASCP at 27 degrees C or DHCA at 18 degrees C for 90 min. Cerebral oxygen extraction fraction (COEF) from blood as well as cerebral tissue glucose, glycerol, lactate, pyruvate, and the lactate/pyruvate ratio (L/P ratio) by microdialysis were obtained repeatedly. RESULTS: COEF was lower during cooling and rewarming, respectively, in the DHCA18 group compared to the ASCP27 group (30 +/- 8 vs 56 +/- 13% and 35 +/- 6 vs 58 +/- 7%, respectively). Glucose decreased in both the DHCA18 and ASCP27 groups during the course of cardiopulmonary bypass (CPB), but were higher in the ASCP27 group during ASCP, compared to the DHCA18 group during circulatory arrest (0.7 +/- 0.1 vs 0.2 +/- 0.1 mm.l(-1), P < 0.05). Pyruvate was higher (ASCP27 vs DHCA18: 53 +/- 17 vs 6 +/- 2 microm.l(-1), P < 0.05), and the L/P ratio increased during circulatory arrest in the DHCA18 group, compared to the selective perfusion phase of the ASCP27 group (DHCA18 vs ASCP27: 1891 +/- 1020 vs 70 +/- 28, P < 0.01). CONCLUSIONS: In this piglet model, both cerebral oxygenation and microdialysis findings suggested a depletion of cerebral energy stores during circulatory arrest in the DHCA18 group, compared to selective cerebral perfusion combined with circulatory arrest in the ASCP27 group.

Laryngeal tube S II, ProSeal laryngeal mask, and EasyTube during elective surgery: a randomized controlled comparison with the endotracheal tube in nontrained professionals.

BACKGROUND AND OBJECTIVE: EasyTube (EZT), ProSeal laryngeal mask airway (PLMA), and Laryngeal tube S II (LTS II) have recently been introduced as supraglottic airway devices and have been proposed as emergency airway alternatives. The purpose of this study was to compare the performance of the three devices, if used by anaesthesiologists without extensive hands-on training, with the endotracheal tube during routine surgical procedures. METHODS: After informed consent, 88 ASA I-II patients scheduled for routine minor surgery were randomly allocated to EZT (n=22), PLMA (n=22), and LTS II (n=22) groups and the endotracheal tube (n=22) group, respectively. Overall success rates, insertion times, cuff pressures, and resulting airway leak pressures as well as subjective assessment of handling were determined. RESULTS: Overall insertion success rate of the EZT, PLMA, LTS II, and endotracheal tube was 14 out of 22 (64%), 20 out of 22 (91%), 21 out of 22 (96%), and 21 out of 22 (96%), respectively. Time to first successful ventilation with the EZT was significantly (P<0.05) longer than that with PLMA, LTS II, and endotracheal tube [median (minimum-maximum): 56 (27-150), 25 (12-70), 24 (11-150), and 20 (8-74) s, respectively]. The lowest airway leak pressure could be observed with the EZT [median (minimum-maximum), 19 (9-40) cmH2O] and the highest airway leak pressure with the LTS II [median (minimum-maximum), 40 (22-40) cmH2O]. Subjective assessment of handling was significantly (P<0.05) poorer in the EZT group compared with PLMA, LTS II, and endotracheal tube groups, respectively. CONCLUSION: In contrast to the EZT, both PLMA and LTS II proved to be suitable for routine airway management by anaesthesiologists without extensive hands-on device training.

Cerebral effects of three resuscitation protocols in uncontrolled haemorrhagic shock: a randomised controlled experimental study.

BACKGROUND: To compare haemodynamic and cerebral variables during aggressive fluid resuscitation vs. administration of a hypertonic starch solution (HS) combined with either noradrenaline [norepinephrine] or arginine vasopressin in an animal model of uncontrolled haemorrhagic shock. METHODS: After Animal Investigational Committee approval, 24 anaesthetised pigs underwent a liver trauma. At haemodynamic decompensation, animals were randomly assigned to receive fluid resuscitation (6% HES 130/0.4, 20 mL/kg, and Ringer, 40 mL/kg; FR group, n=8), or noradrenaline (bolus 20 microg/kg, continuously 1 microg/kg/min) combined with HS (7.2% NaCl/6% HES 200/0.5; 4 mL/kg) (n=8; NA/HS group), or vasopressin (bolus 0.2U/kg, continuously 0.04 U/kg/min) combined with HS (4 mL/kg) (n=8; AVP/HS group), respectively. Thirty minutes after drug administration, bleeding was controlled manually. RESULTS: Mean arterial blood pressure (MAP), cerebral perfusion pressure (CPP), and brain tissue oxygen pressure (P(bt)O(2)) decreased significantly with haemorrhage in all groups (p<0.05). AVP/HS resulted in a faster and higher increase of MAP and CPP compared to both NA/HS and FR (p<0.001 vs. FR; p<0.01 vs. NA/HS). Compared to FR, P(bt)O(2) increased faster with AVP/HS and NA/HS (p<0.05) after therapy, and ICP was lower at the end of the study period (p<0.05). All animals (8/8) of the AVP/HS group survived, compared to 4/8 and 4/8 in the NA/HS and FR group, respectively (p=0.07). CONCLUSIONS: Following uncontrolled haemorrhagic shock in this animal model, combination of HS with arginine vasopressin increased CPP and cerebral oxygenation faster than aggressive fluid resuscitation, without re-increasing ICP.

Impact of different compression-ventilation ratios during basic life support cardiopulmonary resuscitation.

BACKGROUND: The 2005 revised guidelines for cardiopulmonary resuscitation (CPR) suggest a universal compression-to-ventilation (C:V) ratio of 30:2. The effects of this ratio in a realistic CPR scenario have not been investigated completely. MATERIAL AND METHODS: After 4 min of untreated ventricular fibrillation (VF), 24 pigs were randomly assigned to 6 min of basic-life support (BLS) CPR with 21% oxygen, and either (1) chest compressions only ("CC" group, n=8), or (2) cycles of 30 compressions followed by two breaths with a self-inflating bag (Fio2 0.21, C:V ratio 30:2; "30:2" group, n=8), or (3) 15 compressions followed by two breaths (C:V ratio 15:2; "15:2" group, n=8), all followed by advanced life support. RESULTS: Arterial PO2 during BLS-CPR was higher in the 15:2 group compared to the 30:2 and CC groups (74+/-3 vs. 59+/-2 and 33+/-4 mmHg, respectively; p<0.05). Both mixed-venous PO2 and SO2 were higher in the 15:2 and 30:2 groups, compared to the CC group ( PO2 : 23+/-2 and 25+/-1 vs. 17+/-1 mmHg; SO2: 21+/-6 and 19+/-3 vs. 8+/-1 %, respectively; p<0.05). Arterial pH decreased in the 30:2 and CC groups compared to the 15:2 group (7.33+/-0.03 and 7.25+/-0.02 vs. 7.51+/-0.04, respectively; p<0.001). 4/8, 2/8, and 0/8 animals in the 15:2, 30:2, and CC groups, respectively, had ROSC at the end of the study period (p=ns). CONCLUSIONS: Increasing the chest compression ratio from 15:2 to 30:2 resulted in changes in arterial, but not mixed-venous, blood gases; therefore, the advantages of more chest compressions may outweigh a decrease in gas exchange.

Regional and local brain oxygenation during hemorrhagic shock: a prospective experimental study on the effects of small-volume resuscitation with norepinephrine.

BACKGROUND: Patients with uncontrolled hemorrhage may benefit if resuscitation with large amounts of fluids is replaced by a small volume or vasopressor until surgery. Norepinephrine (NE) is commonly used as a vasopressor to control hypotension. The purpose of this study was to compare the effects of hypertonic-hyperoncotic saline starch solution (HHS) either alone or combined with NE on brain tissue oxygen pressure (PbtO2) and brain oxygen saturation (rSO2) in a model of uncontrolled hemorrhage. METHODS: After approval of the animal investigation committee, 22 anesthetized pigs underwent simulated penetrating liver trauma. At hemodynamic decompensation, animals were randomly assigned to receive HHS (Hyperhaes; 4 mL/kg; n = 8) with normal saline placebo, low-dose NE (low NE; 500 microg, and 1 microg/kg/min; n = 7), or high-dose NE (high NE; 1,000 microg, and 1 microg/kg/min; n = 7). Bleeding was controlled manually 30 minutes after drug administration. RESULTS: Cerebral perfusion pressure (CePP), PbtO2, and rSO2 decreased with hemorrhage in all groups (baseline vs. decompensation, CePP-HHS, 83 +/- 5 mm Hg vs. 9 +/- 1 mm Hg; low NE, 67 +/- 6 mm Hg vs. 16 +/- 2 mm Hg; high NE, 77 +/- 7 mm Hg vs. 15 +/- 1 mm Hg. PbtO2-HHS, 100% vs. 29%; low NE, 100% vs. 33%; high NE, 100% vs. 27%. rSO2-HHS, 100% vs. 70%; low NE, 100% vs. 76%; high NE, 100% vs. 63%). Therapy with HHS, low NE, and high NE resulted in a comparable increase of CePP, PbtO2, and rSO2, respectively (5 minutes after therapy, CePP-HHS, 29 +/- 3 mm Hg; low NE, 27 +/- 3 mm Hg; high NE, 28 +/- 3 mm Hg. PbtO2-HHS, 207%; low NE, 129%; high NE, 170%. rSO2-HHS, 94%; low NE, 83%; high NE, 87%). Overall survival was six of eight, four of seven, and six of seven, respectively. CONCLUSION: After uncontrolled hemorrhagic shock, addition of different dosages of NE to HHS, compared with HHS alone, showed no beneficial effect on CePP, rSO2, or PbtO2.

Measurement of blood flow index during antegrade selective cerebral perfusion with near-infrared spectroscopy in newborn piglets.

BACKGROUND: Neonates with complex congenital heart defects have traditionally undergone surgery during deep hypothermic cardiac arrest (HCA). Selective cerebral perfusion (SCP) is thought to minimize ischemic brain injury by providing adequate cerebral blood flow. We investigated SCP with different flow rates compared with HCA with respect to cerebral perfusion and tissue oxygenation as assessed by near-infrared spectroscopy. METHODS: Twenty-one piglets were placed on cardiopulmonary bypass at 18 degrees C, then underwent either HCA or SCP at 25 or 50 mL x kg(-1) x min(-1) for 90 min. The blood flow index (BFI) derived by indocyanine green and tissue oxygen index (TOI) were determined by near-infrared spectroscopy. Mean cerebral blood flow velocity (FV(mean)) was recorded by transcranial Doppler ultrasound. RESULTS: Both BFI and FV(mean) increased significantly (126 +/- 27% of baseline; 19 +/- 2 cm/s) in the SCP 50 group compared with HCA (no flow) and SCP 25 (65 +/- 24%; 10 +/- 1 cm/s), respectively. TOI increased in the SCP 50 group compared with baseline (74 +/- 4% vs 65 +/- 4%), and was higher compared with HCA (52 +/- 2%) and SCP 25 (59 +/- 2%). Intracranial pressure increased nonsignificantly compared with baseline in the SCP 50 group. CONCLUSIONS: Both BFI and FV(mean) suggested increased cerebral perfusion in the SCP 50 group compared with the HCA and SCP 25 groups. TOI was significantly higher in both the SCP 25 and SCP 50 groups compared with HCA. SCP at 25 mL x kg(-1) x min(-1) may be most appropriate for cerebral protection.

Release of protein S100B in haemorrhagic shock: effects of small volume resuscitation combined with arginine vasopressin.

BACKGROUND: The present study was designed to evaluate the effect of conventional fluid resuscitation and small volume resuscitation alone and combined with arginine vasopressin (AVP) on cerebral perfusion pressure (CPP) and protein S100B during experimental haemorrhagic shock. MATERIAL AND METHODS: Thirty anaesthetised pigs underwent a penetrating liver trauma. Following haemodynamic decompensation, pigs received either (1) a combination of crystalloid (40 mL kg(-1)) and colloid (20 mL kg(-1)) solutions (fluid, n=10), (2) hypertonic-hyperoncotic solution (HHS; 4 mL kg(-1)) combined with normal saline (HHS+NS; n=10) or (3) HHS combined with AVP (0.2 U kg(-1) followed by an infusion of 2 U kg(-1)h(-1); HHS+AVP; n=10). RESULTS: Compared to baseline, CPP decreased and S100B levels increased significantly at haemodynamic decompensation (S100B: fluid, 0.52+/-0.23 microg L(-1) vs. 0.85+/-0.37 microg L(-1), p<0.05; HHS+NS, 0.47+/-0.18 microg L(-1) vs. 0.90+/-0.33 microg L(-1), p<0.05; HHS+AVP, 0.53+/-0.18 microg L(-1) vs. 0.90+/-0.39 microg L(-1), p<0.01). During the initial 10 min of therapy, CPP of HHS+NS was significantly higher compared to the fluid group, increased more rapidly in the HHS+AVP group, but was not significantly different thereafter. S100B levels decreased close to baseline values (p<0.001), and did not differ between groups. CONCLUSION: HHS+AVP resulted in higher CPP compared to fluid and HHS+NS in the initial phase of therapy, but did not differ thereafter. Haemorrhage-induced hypotension yielded increased S100B levels that were comparable in groups throughout the study period.

Impact of norepinephrine and fluid on cerebral oxygenation in experimental hemorrhagic shock.

Few data exist regarding resuscitation of hypovolemic shock in infants, and alternative strategies such as vasopressor therapy merit further evaluation. However, the effects of norepinephrine on cerebral perfusion and oxygenation during hemorrhagic shock in the pediatric population are still unclear. Eight anesthetized piglets were subjected to hypotension by blood withdrawal of 25 mL/kg. Norepinephrine was titrated to achieve baseline mean arterial blood pressure (MAP), and cerebral oxygenation was determined by brain tissue Po2 (Ptio2) and near-infrared spectroscopy-derived tissue oxygen index (TOI). Then, norepinephrine was stopped, MAP was allowed to decrease again below 30 mm Hg, and shed blood was retransfused. During hemorrhage, TOI dropped from 69+/-3 to 59+/-3%, and Ptio2 from 29+/-6 to 13+/-1 mm Hg (mean+/-SEM; p<0.001). Following norepinephrine, cerebral perfusion pressure (CPP) could be restored immediately, whereas TOI and Ptio2 did not increase significantly. In contrast, following retransfusion, TOI and Ptio2 increased to 68+/-3% and 27+/-7 mm Hg reaching baseline values, respectively. In conclusion, while norepinephrine increased CPP immediately, cerebral oxygenation as reflected by TOI and Ptio2 could not be improved by norepinephrine, but only by retransfusion.

Arginine vasopressin during sinus rhythm: effects on haemodynamic variables, left anterior descending coronary artery cross sectional area and cardiac index, before and after inhibition of NO-synthase, in pigs.

UNLABELLED: We have shown previously that arginine vasopressin (AVP) given during sinus rhythm increases mean arterial blood pressure (MAP) and left anterior descending (LAD) coronary artery cross sectional area. AVP was assumed to result in vasodilatation via activation of the endothelial nitric oxide system. The purpose of the present study was to assess the effects of AVP before and after NO-inhibition. Nine domestic pigs were instrumented for measurement of haemodynamic variables using micromanometer-tipped catheters, and measurement of LAD coronary artery cross sectional area employing intravascular ultrasound (IVUS). Haemodynamic variables, LAD coronary artery cross sectional area and cardiac output were measured at baseline, 90 s and 5, 15, and 30 min after AVP (0.4 U kg (-1) IV) before and after blockade of nitric oxide synthase with N(G)-nitro L-arginine methyl ester (L-NAME). Compared with baseline, AVP significantly increased MAP after 90 s (89+/-4 versus 160+/-5 mm Hg), increased LAD coronary artery cross sectional area (11.3+/-1 versus 11.8+/-1 mm(2)) and decreased cardiac index (138+/-6 versus 53+/-6 mL/min kg(-1)). After blockade of nitric oxide synthase, AVP significantly increased MAP after 90 s (135+/-4 versus 151+/-3 mm Hg), increased LAD coronary artery cross sectional area (8.7+/-1 versus 8.9+/-1 mm(2)), and significantly decreased cardiac index (95+/-6 versus 29+/-4 mL/min kg (-1)). IMPLICATIONS: During sinus rhythm, AVP increased MAP and LAD coronary artery cross sectional area, but decreased cardiac index.