[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.

[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.

Management of the predicted difficult airway: a comparison of conventional blade laryngoscopy with video-assisted blade laryngoscopy and the GlideScope.

BACKGROUND AND OBJECTIVE: We investigated whether the use of two different video laryngoscopes [direct-coupled interface (DCI) video laryngoscope and GlideScope] may improve laryngoscopic view and intubation success compared with the conventional direct Macintosh laryngoscope (direct laryngoscopy) in patients with a predicted difficult airway. METHODS: One hundred and twenty adult patients undergoing elective minor surgery requiring general anaesthesia and endotracheal intubation presenting with at least one predictor for a difficult airway were enrolled after Institutional Review Board approval and written informed consent was obtained. Repeated laryngoscopy was performed using direct laryngoscope, DCI laryngoscope and GlideScope in a randomized sequence before patients were intubated. RESULTS: Both video laryngoscopes showed significantly better laryngoscopic view (according to Cormack and Lehane classification as modified by Yentis and Lee = C&L) than direct laryngoscope. Laryngoscopic view C&L >or= III was measured in 30% of patients when using direct laryngoscopy, and in only 11% when using the DCI laryngoscope (P < 0.001). The GlideScope enabled significantly better laryngoscopic view (C&L >or= III: 1.6%) than both direct (P < 0.001) and DCI laryngoscopes (P < 0.05). Clinically relevant improvement in the specific 36 patients with insufficient direct view (C&L >or= III) could be achieved significantly more often with the GlideScope (94.4%) than with the DCI laryngoscope (63.8%; P < 0.01). Laryngoscopy time did not differ between instruments [median (range): direct laryngoscope, 13 (5-33) s; DCI laryngoscope, 14 (6-40) s; GlideScope, 13 (5-34) s]. In contrast, tracheal intubation needed significantly more time with both video laryngoscopes [DCI laryngoscope, 27 (17-94) s, P < 0.05 and GlideScope, 33 (18-68) s, P < 0.01] than with the direct laryngoscope [22.5 (12-49) s]. Intubation failed in four cases (10%) using the direct laryngoscope and in one case (2.5%) each using the DCI laryngoscope and the GlideScope. CONCLUSION: We conclude that the video laryngoscope and GlideScope in particular may be useful instruments in the management of the predicted difficult airway.

A national resuscitation registry of out-of-hospital cardiac arrest in Germany-a pilot study.

BACKGROUND: Survival rate after out-of-hospital cardiac arrest (OHCA) has not significantly increased over the last decade. However, survival rate has been used as a quality benchmark for many emergency medical services. A uniform resuscitation registry may be advantageous for quality management of cardiopulmonary resuscitation (CPR). This study was conducted to evaluate the establishment of a national CPR registry in Germany. MATERIALS AND METHODS: A prospective cohort study was performed that included 469 patients who experienced OHCA requiring CPR in the metropolitan area of Dortmund, Germany. Cardiac arrest was defined as concomitant appearance of unconsciousness, apnoea or gasping and pulselessness. All data were collected via a secure and confidential paper-based method as the data set 'Preclinical care'. RESULTS: Quality of data was classified as 'good' in 33.4%, 'moderate' in 48.4%, and 'bad' in 18.2% of the patients, respectively. Sixty-two percent had OHCA in private residences, 24% of the patients had a first monitored rhythm of ventricular fibrillation (VF) or ventricular tachycardia (VT), 35.2% had return of spontaneous circulation (ROSC) on scene, and patients presenting VF/VT as the first monitored rhythm had higher ROSC rates (51.3%) compared to patients with asystole (22.6%). CONCLUSION: The data set 'Preclinical care' proved to be congruent with the Utstein style, provided further information for national and international comparisons, and enabled a detailed analysis. Optimisation of data collection and introduction of strict control mechanisms may further improve data quality.

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.

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.

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.

Evaluation of the pediatric Bonfils fiberscope for elective endotracheal intubation.

BACKGROUND: Difficult airway management in children is a particular challenge for anesthesiologists and pediatricians. This study was designed to evaluate the performance of the recently developed pediatric versions of the Bonfils fiberscope for elective endotracheal intubation during routine surgical procedures. METHODS: After approval by the institutional review board and written informed consent, 55 children (age 6 +/- 4 years) scheduled for elective minor surgical procedures were enrolled. Nineteen children received atropine before the intubation attempt, while in the remaining 36 children, no antisialogogue was used. For endotracheal tubes up to 3.5 mm internal diameter, a fiberscope with outer diameter (OD) 2 mm, and for larger endotracheal tubes, a fiberscope OD 3.5 mm was used. Time to intubation and failure rate were obtained. RESULTS: In the 36 children without and the 19 children with atropine pretreatment, the success rate for tracheal intubation on the first attempt was 69%/78% (25/15 patients). 4/3 patients and 2/0 patients were intubated after two and three attempts, respectively, and in 5/1 patients (14%/5%) intubation failed even after three attempts. Time to intubation was median 58/60 s, 25th-75th percentile 35-100/32-110 s, and range 14-377/18-360 s. In both groups, failed intubations were because of the secretions contaminating the optic aperture. CONCLUSIONS: High failure rate and increased intubation times suggest that the pediatric Bonfils fiberscope has significant drawbacks when used for intubation of normal pediatric airways.

[Inter-hospital transfer of patients in intensive care treatment. A systematic review]. / Interhospitaltransfer - Indikationen, Ablauf und Organisation.

An obvious trend of concentrating treatment options on specialized centres may take effect later in an increased need for inter-hospital transfer. Patients initially referred to secondary or tertiary hospitals require a safe and systematically organised transport in order to ensure a continuation of initiated actions in intensive care. This review will focus of appropriate preparations, equipment and transport modalities, possible sources of shortcomings as well as solutions of conflicts during inter-hospital transfers.

[The DGAI CPR registry - the datasets "hospital care" and "long-term process"]. / Das DGAI-Reanimationsregister - Die Datensätze "Weiterversorgung" und "Langzeitverlauf"

After several years of preparation the German Society of Anaesthesiology and Intensive Care Medicine (Deutsche Gesellschaft für Anästhesiologie und Intensivmedizin--DGAI) has, during its annual conference 2007, officially launched the DGAI CPR registry. After implementation of the dataset "primary care" in 2004, the datasets "definite care" and "long-term process" have now been released. The completed, internet based database is open for any interested person or institution as a tool for quality management. Data may be recorded online, and basic analyses be performed immediately. Beyond that benchmarks with other institutions are possible, by including the well accepted Utstein style on international level too.

Revised resuscitation guidelines: adrenaline versus adrenaline/vasopressin in a pig model of cardiopulmonary resuscitation--a randomised, controlled trial.

BACKGROUND: Synergistic effects of adrenaline (epinephrine) and vasopressin may be beneficial during cardiopulmonary resuscitation. However, it is unknown whether either adrenaline alone or an alternating administration of adrenaline and vasopressin is better for restoring vital organ perfusion following basic life support (BLS) according to the revised algorithm with a compression-to-ventilation (c/v) ratio of 30:2. MATERIAL AND METHODS: After 4min of ventricular fibrillation, and 6min of BLS with a c/v ratio of 30:2, 16 pigs were randomised to receive either 45microg/kg adrenaline, or alternating 45microg/kg adrenaline and 0.4U/kg vasopressin, respectively. RESULTS: Coronary perfusion pressure (mean+/-S.D.) 20 and 25min after cardiac arrest was 7+/-4 and 5+/-3mm Hg after adrenaline, and 25+/-2 and 14+/-3mm Hg after adrenaline/vasopressin (p<0.001 and <0.01 versus adrenaline), respectively. Cerebral perfusion pressure was 23+/-7 and 19+/-9mm Hg after adrenaline, and 40+/-10 and 33+/-7mm Hg after adrenaline/vasopressin (p<0.001 and <0.01 versus adrenaline), and cerebral blood flow was 30+/-10 and 27+/-11% of baseline after adrenaline, and 65+/-40 and 50+/-31% of baseline after adrenaline/vasopressin (p<0.05 versus adrenaline), respectively. Return of spontaneous circulation (ROSC) did not differ significantly between the adrenaline group (0/8) and the adrenaline/vasopressin group (3/8). CONCLUSION: Adrenaline/vasopressin resulted in higher coronary and cerebral perfusion pressures, and cerebral blood flow, while ROSC was comparable.

[Hypothermia after cardiac arrest--daily trained clinical practice? A survey at northern Germany hospitals]. / Milde Hypothermie nach Reanimation--Standardtherapie an norddeutschen Krankenhäusern?

Hypothermia after out of hospital cardiac arrest should be clinical practice for years. But is it really meanwhile daily trained practice? A survey at northern German hospitals gives an answer to this question.

Brain tissue oxygen pressure and cerebral metabolism in an animal model of cardiac arrest and cardiopulmonary resuscitation.

OBJECTIVE: Direct measurement of brain tissue oxygenation (PbtO2) is established during spontaneous circulation, but values of PbtO2 during and after cardiopulmonary resuscitation (CPR) are unknown. The purpose of this study was to investigate: (1) the time-course of PbtO2 in an established model of CPR, and (2) the changes of cerebral venous lactate and S-100B. METHODS: In 12 pigs (12-16 weeks, 35-45 kg), ventricular fibrillation (VF) was induced electrically during general anaesthesia. After 4 min of untreated VF, all animals were subjected to CPR (chest compression rate 100/min, FiO2 1.0) with vasopressor therapy after 7, 12, and 17 min (vasopressin 0.4, 0.4, and 0.8 U/kg, respectively). Defibrillation was performed after 22 min of cardiac arrest. After return of spontaneous circulation (ROSC), the pigs were observed for 1h. RESULTS: After initiation of VF, PbtO2 decreased compared to baseline (mean +/- SEM; 22 +/- 6 versus 2 +/- 1 mmHg after 4 min of VF; P < 0.05). During CPR, PbtO2 increased, and reached maximum values 8 min after start of CPR (25 +/- 7 mmHg; P < 0.05 versus no-flow). No further changes were seen until ROSC. Lactate, and S-100B increased during CPR compared to baseline (16 +/- 2 versus 85 +/- 8 mg/dl, and 0.46 +/- 0.05 versus 2.12 +/- 0.40 microg/l after 13 min of CPR, respectively; P < 0.001); lactate remained elevated, while S-100B returned to baseline after ROSC. CONCLUSIONS: Though PbtO2 returned to pre-arrest values during CPR, PbtO2 and cerebral lactate were lower than during post-arrest reperfusion with 100% oxygen, which reflected the cerebral low-flow state during CPR. The transient increase of S-100B may indicate a disturbance of the blood-brain-barrier.

Cerebral metabolism assessed with microdialysis in uncontrolled hemorrhagic shock after penetrating liver trauma.

In a porcine model of uncontrolled hemorrhagic shock, we evaluated the effects of fluid resuscitation versus arginine vasopressin (AVP) combined with hypertonic-hyperoncotic hydroxyethyl starch solution (HHS) on cerebral perfusion pressure (CPP) and on cerebral metabolism using intracerebral microdialysis. Sixteen anesthetized pigs were subjected to uncontrolled liver bleeding until hemodynamic decompensation, followed by resuscitation using either fluid (n = 8) or AVP/HHS (n = 8). Thirty minutes after drug administration, bleeding was controlled by manual compression, and colloid and crystalloid solutions were administered in both groups. All surviving animals were observed for one hour. After hemodynamic decompensation, fluid resuscitation resulted in a smaller increase of CPP than did AVP/HHS (mean +/- sem; 24 +/- 5 vs 45 +/- 7 mm Hg; P < 0.01). Mean (+/- sem) cerebral venous partial pressure of oxygen was significantly decreased (P < 0.01) 5 min after fluid compared with 5 min after AVP/HHS administration (36 +/- 3 vs 64 +/- 4 torr). Cerebral metabolism was comparable in both groups. In conclusion, AVP/HHS proved to be superior to fluid in the initial phase of therapy with respect to CPP and cerebral oxygenation, but was comparable to fluid regarding cerebral metabolism and secondary cell damage in surviving animals.

[Clinical management of the difficult airway]. / Klinisches Management des schwierigen Atemwegs.

Difficult airway management is among the key requirements in routine anaesthesia. Failures to secure the airways resulting in a "Cannot intubate, Cannot ventilate" situation can drastically increase morbidity and mortality of patients within a very short time. Therefore, an algorithm for management of the expected and unexpected difficult airway describing the sequence of various procedures, adapted to internal standards and to techniques that are available, has to be provided by each anaesthesia department. This not only facilitates the preparation of equipment and the training of personnel, but also ensures efficient decision making under time pressure.

A new universal laryngoscope blade: a preliminary comparison with Macintosh laryngoscope blades.

The Dörges universal laryngoscope blade has several features designed to facilitate tracheal intubation. The number of laryngoscope blades may be reduced from four to two, or even one, which indicate less space requirement and costs. This new universal laryngoscope blade, has a lower profile (height 15 vs. 22 mm) than a Macintosh laryngoscope blade size 3 and 4, which may facilitate manoeuvring of the laryngoscope in the mouth. In random order, 40 non-anaesthesia senior house officers used a Macintosh laryngoscope blade size 3 or 4 in an adult airway management trainer, a Macintosh laryngoscope blade size 2 in a paediatric airway management trainer, and the Dörges universal laryngoscope blade for both airway management trainers to perform orotracheal intubation. The number of intubation attempts and failures was counted. Participants reported the laryngoscopic view according to Cormack and Lehane. The time from touching the laryngoscope to the first adequate lung insufflation was measured, and subjective assessment regarding handling of both blades was recorded. Number of intubation failures, the laryngoscopic view according to Cormack and Lehane, and subjective assessment was comparable between groups. Orotracheal intubation of the adult airway management trainer with the Dörges universal laryngoscope blade took significantly less time compared to the Macintosh laryngoscope blades (14 (7-57) vs. 20 (8-43) s; P<0.001); all other intubating times were comparable. In conclusion, in this model, the Dörges universal laryngoscope blade was comparable to the Macintosh laryngoscope blades size 2-4, and may save time, cost and space.

Effects of decreasing inspiratory flow rate during simulated basic life support ventilation of a cardiac arrest patient on lung and stomach tidal volumes.

If the airway of a cardiac arrest patient is unprotected, basic life support with low rather than high inspiratory flow rates may reduce stomach inflation. Further, if the inspiratory flow rate is fixed such as with a resuscitator performance may improve; especially when used by less experienced rescuers. The purpose of the present study was to assess the effect of limited flow ventilation on respiratory variables, and lung and stomach volumes, when compared with a bag valve device. After institutional review board approval, and written informed consent was obtained, 20 critical care unit registered nurses volunteered to ventilate a bench model simulating a cardiac arrest patient with an unprotected airway consisting of a face mask, manikin head, training lung [with lung compliance, 50 ml/0.098 kPa (50 ml/cmH(2)O); airway resistance, 0.39 kPa/l/s (4 cmH(2)O/l/s)] oesophagus [lower oesophageal sphincter pressure, 0.49 kPa (5 cmH(2)O)] and simulated stomach. Each volunteer ventilated the model with a self-inflating bag (Ambu, Glostrup, Denmark; max. volume, 1500 ml), and a resuscitator providing limited fixed flow (Oxylator EM 100, CPR Medical devices Inc., Toronto, Canada) for 2 min; study endpoints were measured with 2 pneumotachometers. The self-inflating bag vs. resuscitator resulted in comparable mean +/- SD mask tidal volumes (945 +/- 104 vs. 921 +/- 250 ml), significantly (P < 0.05) higher peak inspiratory flow rates (111 +/- 27 vs. 45 +/- 21 l/min), and peak inspiratory pressure (1.2 +/- 0.47 vs. 78 +/- 0.07 kPa), but significantly shorter inspiratory times (1.1 +/- 0.29 vs. 1.6 +/- 0.35 s). Lung tidal volumes were comparable (337 +/- 120 vs. 309 +/- 61 ml), but stomach tidal volumes were significantly (P < 0.05) higher (200 +/- 95 vs. 140 +/- 51 ml) with the self-inflating bag. In conclusion, simulated ventilation of an unintubated cardiac arrest patient using a resuscitator resulted in decreased peak flow rates and therefore, in decreased peak airway pressures when compared with a self-inflating bag. Limited flow ventilation using the resuscitator decreased stomach inflation, although lung tidal volumes were comparable between groups.

Decreasing peak flow rate with a new bag-valve-mask device: effects on respiratory mechanics, and gas distribution in a bench model of an unprotected airway.

Reducing inspiratory flow rate and peak airway pressure may be important in order to minimise the risk of stomach inflation when ventilating an unprotected airway with positive pressure ventilation. The purpose of this study was to assess the effects of a newly developed bag-valve-mask device (SMART BAG), O-Two Systems International, Ont., Canada) that limits peak inspiratory flow. A bench model simulating a patient with an unintubated airway was used consisting of a face mask, manikin head, training lung (lung compliance, 100 ml/cm H(2)O, airway resistance 4 cm H(2)O/l/s, lower oesophageal sphincter pressure 20 cm H(2)O and simulated stomach). Twenty nurses were randomised to each ventilate the manikin using a standard single person technique for 1 min (respiratory rate, 12/min) with either a standard adult self-inflating bag, or the SMART BAG. The volunteers were blinded to the experimental design of the model until completion of the experimental protocol. The SMART BAG vs. standard self-inflating bag resulted in significantly (P<0.05) lower mean+/-S.D. peak inspiratory flow rates (32+/-2 vs. 61+/-13 l/min), peak inspiratory pressure (12+/-2 vs. 17+/-2 cm H(2)O), lung tidal volumes (525+/-111 vs. 680+/-154 ml) and stomach tidal volumes (0+/-0 vs. 17+/-36 ml), longer inspiratory times (1.9+/-0.3 vs. 1.5+/-0.3 s), but significantly higher mask leakage (26+/-13 vs. 14+/-8%); mask tidal volumes (700+/-104 vs. 785+/-172 ml) were comparable. The mask leakage observed is not an uncommon factor in bag-valve-mask ventilation with leakage fractions of 25-40% having been previously reported. The differences observed between the standard BVM and the SMART BAG are due more to the anatomical design of the mask and the non-anatomical shape of the manikin face than the function of the device. Future studies should remove the mask to manikin interface and should introduce a standardized mask leakage fraction. The use of a two-person technique may have removed the problem of mask leakage. In conclusion, using the SMART BAG during simulated ventilation of an unintubated patient in respiratory arrest significantly decreased inspiratory flow rate, peak inspiratory pressure, stomach tidal volume, and resulted in a significantly longer inspiratory time when compared to a standard self-inflating bag.

Optimizing bag-valve-mask ventilation with a new mouth-to-bag resuscitator.

When ventilating an unintubated patient with a self-inflating bag, high peak inspiratory flow rates may result in high peak airway pressure with subsequent stomach inflation; this may occur frequently when rescuers without daily experience in bag-valve-mask ventilation need to perform advanced airway management. The purpose of this study was to assess the effects of a newly developed self-inflating bag (mouth-to-bag resuscitator; Ambu, Glostrup, Denmark) that limits peak inspiratory flow. A bench model simulating a patient with an unintubated airway was used, consisting of a face mask, manikin head, training lung (lung compliance, 100 ml/0.098 kPa (100 ml/cm H(2)O)); airway resistance, 0.39 kPa/l per second (4 cm H(2)O/l/s), oesophagus (LESP, 1.96 kPa (20 cm H(2)O)) and simulated stomach. Twenty nurses were randomised to ventilate the manikin for 1 min (respiratory rate: 12 per minute) with either a standard self-inflating bag or the mouth-to-bag resuscitator, which requires the rescuer to blow up a single-use balloon inside the self-inflating bag, which in turns displaces air towards the patient. When supplemental oxygen is added, ventilation with up to 100% oxygen may be obtained, since expired air is only used as the driving gas. The mouth-to-bag resuscitator therefore allows two instead of one hand sealing the mask on the patient's face. The volunteers were blinded to the experimental design of the model until completion of the experimental protocol. The mouth-to-bag resuscitator versus standard self-inflating bag resulted in significantly (P<0.05) higher mean+/-S.D. mask tidal volumes (1048+/-161 vs. 785+/-174 ml) and lung tidal volumes (911+/-148 vs. 678+/-157 ml), longer inspiratory times (1.7+/-0.4 vs. 1.4+/-0.4 s), but significantly lower peak inspiratory flow rates (50+/-9 vs. 62+/-13 l/min) and mask leakage (10+/-4 vs. 15+/-9%); peak inspiratory pressure (17+/-2 vs. 17+/-2 cm H(2)O) and stomach tidal volumes (16+/-30 vs. 18+/-35 ml) were comparable. In conclusion, employing the mouth-to-bag resuscitator during simulated ventilation of an unintubated patient in respiratory arrest significantly decreased inspiratory flow rate and improved lung tidal volumes, while decreasing mask leakage.