Cadaver study of oesophageal insufflation with supraglottic airway devices during positive pressure ventilation in an obstructed airway.

BACKGROUND: Supraglottic airway devices (SADs) play an increasing role in airway management in clinical anaesthesia and emergency medicine. Until now, no data exist concerning the extent of oesophageal insufflation when oropharyngeal leak pressures are exceeded. METHODS: Laryngeal masks LMA-Supreme™ and LMA-ProSeal™, laryngeal tubes LTS-D and LTS II, Combitube™, and I-Gel were inserted into unfixed human cadavers. The oesophagus was connected to a volumeter, while the trachea was closed surgically to simulate complete airway obstruction. Volumes of oesophageal insufflation resulting from pressure-controlled ventilation at inspiratory pressures of 20, 40, and 60 mbar were measured. RESULTS: No oesophageal insufflation could be detected at a ventilation pressure of 20 mbar in any device. Using inspiratory pressures of 40 and 60 mbar, oesophageal insufflation occurred in all devices, with significantly higher volumes of intraoesophageal air for both laryngeal tubes. CONCLUSIONS: The use of SADs with inspiratory pressures of 20 mbar appears to be safe regarding the risk of intragastric insufflation. Higher inspiratory pressures should be strictly avoided.

[Estimation of substitution volume after burn trauma. Systematic review of published formulae]. / Abschätzung des Substitutionsvolumens nach Verbrennungstrauma. Systematische Übersichtsarbeit über publizierte Formeln.

BACKGROUND: Fluid resuscitation after severe burns remains a challenging task particularly in the preclinical and early clinical phases. To facilitate volume substitution after burn trauma several formulae have been published and evaluated, nevertheless, the optimal formula has not yet been identified. METHODS: A systematic PubMed search was performed to identify published formulae for fluid resuscitation after severe burns. The search terms "burn", "thermal", "treatment", "therapy" or "resuscitation", "fluid", "formula" and "adult", "pediatric" or "paediatric" were used in various combinations. Analysis was limited to the period from 01.01.1950 to 30.06.2010 and database entries in PubMed (http://www.pubmed.com). Additionally, references cited in the papers were analyzed and relevant publications were also included. Publications and formulae were assessed and classified by two independent investigators. RESULTS: Within the specified time frame eight publications (five original contributions and three book chapters) were identified of which three formulae recommended colloid solutions, four recommended electrolyte solutions and one suggested hypertonic solutions within the first 24 h for fluid resuscitation. Only one formula specifically dealt with fluid resuscitation in infants. CONCLUSION: The identified formulae led to sometimes strikingly diverse calculations of resuscitation fluid volumes. Therefore their use should be monitored closely and clinical values included. Urine output is a well established individual parameter. Use of colloid and hypertonic solutions leads to a reduced total fluid volume but is still controversially discussed.

[Endotracheal tubes in pediatric patients. Published formulas to estimate the optimal size]. / Endotrachealtuben bei Kindern. Publizierte Formeln zur Abschätzung der optimalen Größe.

BACKGROUND: Estimating the endotracheal tube size with the optimal internal diameter (ID) is of outstanding importance for airway management in pediatric patients. For many years different weight, height, and/or age-based formulas have been published. The aim of the present study was to identify and to compare published formulas to estimate optimal tube size in pediatric patients. MATERIALS AND METHODS: A PubMed search was performed to identify published formulas for tube diameter in pediatric patients. The keywords "pediatric" or "paediatric", "anesthesia" or "anaesthesia", "anaesthesiology" or "anesthesiology", "size", "formula", "diameter", "tube" or "endotracheal tube" were used. Analysis was limited to articles published between 01.01.1951 and 30.06.2009. Additionally, similar publications retrieved from PubMed (related articles) and cited references were identified. Publications and formulas were assessed and classified by two independent colleagues. RESULTS: In the specified time-frame, 13 publications (11 original contributions and 2 letters to the editor) were identified with PubMed and 3 more formulas with the extended search. Altogether 22 formulas to estimate appropriate endotracheal tube size for pediatric patients (age 0-18 years) were identified: 12 age-based formulas for tubes without a cuff, 4 height-based formulas for tubes without a cuff, 2 weight-based formulas for tubes without a cuff and one multivariate formula for tubes without a cuff as well as 3 age-based formulas for cuffed endotracheal tubes. CONCLUSIONS: The identified formulas were comparatively simple to apply but were validated only for pediatric patients older than 1 year. Using tubes with a cuff can minimize the problem of optimal tube size. If a tube without a cuff is intended to be used other sizes should also be available.

[Tonsillectomy in children: preoperative evaluation of risk factors]. / Tonsillektomie bei kindern: präoperative evaluation von risikofaktoren.

Tonsillectomy is one of the most frequently performed surgical procedures in children and is associated with a relatively high risk of postoperative complications. The question often arises whether paediatric obstructive sleep apnoea should be diagnosed with preoperative sleep testing and whether preoperative coagulation tests should be performed in every child undergoing tonsillectomy. In order to answer these questions, the relevant German and English literature was analysed. Adenotonsillectomy in childhood usually resolves the underlying sleep-related breathing disorder. Nevertheless, especially in children with clinical risk factors such as severe sleep apnoea, obesity or craniofacial malformation, respiratory complications should be expected in the postoperative phase. Routine sleep tests prior to tonsillectomy are neither necessary nor practical for preoperative evaluation. Inherited coagulation disorders have only a limited effect on the occurrence of postoperative bleeding and the predictive value of routine coagulation tests is limited. As long as a thorough clinical history is negative, routine coagulation tests are not helpful or necessary prior to tonsillectomy in children.

[Infrastructure of emergency medical services. Comparison of physician-staffed ambulance equipment in the state of Baden-Wuerttemberg in 2001 and 2005]. / Strukturqualität im Notarztdienst. Vergleich der Ausstattung arztbesetzter Rettungsmittel in Baden-Württemberg in den Jahren 2001 und 2005.

BACKGROUND: A survey amongst emergency physician bases in the federal state of Baden-Wuerttemberg in 2001 concerning equipment available for airway management and the treatment of acute coronary syndromes showed striking differences with respect to implementation of European norms and international recommendations. The survey was repeated in 2005 to evaluate the development of the equipment in physician-staffed ambulance systems. METHODS: A questionnaire was sent to all emergency physician bases (ground ambulance and helicopter) registered with the Ministry of Health in Baden-Wuerttemberg. Questions encompassed availability of options to verify correct tracheal tube position (e.g. capnometry), supraglottic airway devices as alternatives to mask ventilation and tracheal intubation, 12-lead ECG and fibrinolytic agents. RESULTS: In 2001, 116 out of 127 bases (91.3%) participated and in 2005, 107 out of 120 bases (89.2%) returned the questionnaire. With availability in 97.2% of bases, prevalence of supraglottic airway devices is almost state-wide (2001: 54.3%, p<0.001, Fisher's exact test). The topics verification of tracheal tube position (2005: 73.8%, 2001: 26.7%, p<0.001), 12-lead ECG (2005: 89.7%, 2001: 52.6%, p<0.001) and fibrinolytic therapy (2005: 59.8%, 2001: 12.9%, p<0.001) showed noticeable increases in the corresponding availability, however, distinct regional structural deficits were still present in 2005. CONCLUSIONS: A favourable trend could be found concerning the equipment of physician-staffed ambulances state-wide. Further efforts must be undertaken to ensure the complete implementation of legal requirements and international recommendations concerning provision of medical equipment.

[Comparison of two different laryngeal mask models for airway management in patients with immobilization of the cervical spine]. / Vergleich von zwei Larynxmaskenmodellen zur Atemwegssicherung bei Patienten mit Immobilisation der Halswirbelsäule.

BACKGROUND: Reduced cervical spine mobility can impair laryngoscopy and tracheal intubation. Supraglottic airway devices can be important alternatives for oxygenation under these circumstances. The Ambu laryngeal mask (ALM) and the LMA-Classic (LMA) are compared in patients with immobilization of the cervical spine. METHODS: In 60 patients scheduled for elective ambulatory interventions, ALM or LMA were inserted after cervical immobilization with an extrication collar and assessment of laryngoscopic view. Insertion time (removal of facemask until first tidal volume), number of insertion attempts, airway leak pressure (cuff pressure 60 cm H(2)O), intraoperative complications and postoperative complaints were assessed. RESULTS: Demographical data, insertion attempts, insertion time (ALM 15.6+/-4.4 s, LMA 15.5+/-4.9 s) and airway leak pressure (ALM 25.6+/-5.2 cm H(2)O, LMA 26.5+/-6.5 cm H(2)O) were comparable. Traces of blood were found in 6 LMAs and 3 ALMs after removal, mild trouble with swallowing (visual analogue scale, VAS 2-4) in the recovery room and after 24 h were complaints by 1 ALM and 2 LMA patients. CONCLUSIONS: LMA-Classic and Ambu laryngeal masks are suitable for rapid and reliable airway management in patients with cervical immobilization.

[Polytrauma with tension pneumothorax with inserted chest tube]. / Polytrauma mit Spannungspneumothorax bei liegender Thoraxdrainage.

The authors report a case of a 25-year-old woman with a polytrauma, caused by a free fall of 12 metres in suicidal intention. Following endotracheal intubation and mechanical ventilation by an emergency physician at the scene, the patient was delivered to the emergency room of an university hospital. An ultrasonic check of the abdomen revealed free fluid in the abdominal cavity, and a rupture of liver and spleen was suspected. Since breath sounds over the right lung were diminished, a chest tube was inserted immediately in the fifth intercostal space in the anterior axillary line. About 300 millilitres of blood were drained by the tube. Shortly thereafter, a laparotomy was performed, where spleen and liver rupture were confirmed and treated. After 60 minutes, the patient developed severe hypotension coupled with ventricular tachycardia and fibrillation, and resuscitation measures had to be initiated. Since breath sounds over the right lung were missing, a tension pneumothorax was suspected and a thoracotomy performed immediately. While huge amounts of air and blood were emerging from the thoracic cavity, a rupture of the right mainstem bronchus as well as of the right pulmonary artery and vena subclavia was identified. The chest tube was found dislocated into the subcutaneous tissue. Despite of open heart compression, application of adrenaline and noradrenaline and substitution of packed red blood cells and of crystalloid and colloid solutions, all resuscitation measures failed so that the patient died shortly after on the operation table. This case illustrates first the difficulties of an adequate thoracic trauma management, particularly, when clinical symptoms are discrete, second the problems of the insertion and control of a chest tube, and third risks associated with wrong position or secondary dislocation which may include - as in our case - "masking" of severe injury patterns and delay of life-saving measures such as an immediate thoracotomy. In order to improve prognosis of patients with poly-/thoracic trauma, establishment of spiral-CT in emergency centres, routine bronchoscopy and safe handling of chest tubes may be helpful.

Automated speech recognition for time recording in out-of-hospital emergency medicine-an experimental approach.

Precise documentation of medical treatment in emergency medical missions and for resuscitation is essential from a medical, legal and quality assurance point of view [Anästhesiologie und Intensivmedizin, 41 (2000) 737]. All conventional methods of time recording are either too inaccurate or elaborate for routine application. Automated speech recognition may offer a solution. A special erase programme for the documentation of all time events was developed. Standard speech recognition software (IBM ViaVoice 7.0) was adapted and installed on two different computer systems. One was a stationary PC (500MHz Pentium III, 128MB RAM, Soundblaster PCI 128 Soundcard, Win NT 4.0), the other was a mobile pen-PC that had already proven its value during emergency missions [Der Notarzt 16, p. 177] (Fujitsu Stylistic 2300, 230Mhz MMX Processor, 160MB RAM, embedded soundcard ESS 1879 chipset, Win98 2nd ed.). On both computers two different microphones were tested. One was a standard headset that came with the recognition software, the other was a small microphone (Lavalier-Kondensatormikrofon EM 116 from Vivanco), that could be attached to the operators collar. Seven women and 15 men spoke a text with 29 phrases to be recognised. Two emergency physicians tested the system in a simulated emergency setting using the collar microphone and the pen-PC with an analogue wireless connection. Overall recognition was best for the PC with a headset (89%) followed by the pen-PC with a headset (85%), the PC with a microphone (84%) and the pen-PC with a microphone (80%). Nevertheless, the difference was not statistically significant. Recognition became significantly worse (89.5% versus 82.3%, P<0.0001 ) when numbers had to be recognised. The gender of speaker and the number of words in a sentence had no influence. Average recognition in the simulated emergency setting was 75%. At no time did false recognition appear. Time recording with automated speech recognition seems to be possible in emergency medical missions. Although results show an average recognition of only 75%, it is possible that missing elements may be reconstructed more precisely. Future technology should integrate a secure wireless connection between microphone and mobile computer. The system could then prove its value for real out-of-hospital emergencies.

[First clinical experiences with the new LTS. A laryngeal tube with an oesophageal drain]. / Erste klinische Erfahrungen mit dem neuen LTS. Ein Larynx-Tubus mit ösophagealer Drainagemöglichkeit.

OBJECTIVE: The feasibility of prototypes of the LTS, a laryngeal tube with an additional oesophageal drain tube for pressure relief, was tested for ventilation during surgery. METHODS: After approval of the ethics committee, a LTS was placed in 30 orthopaedic patients, ASA I and II, induction of general anaesthesia with fentanyl and propofol. Position of the LTS was verified by auscultation and end tidal CO(2)-measurement. Oxygen saturation, number of placement attempts, cuff pressure, time until first tidal volume, tidal volume and airway pressures were registered intraoperatively. Patients were questioned about hoarseness and soar throat 1 h, 6 h and 24 hours after surgery, graded on a visual analogue scale (VAS). RESULTS: 16 women and 14 men were investigated. In 29 patients (96.7%), the LTS was placed successfully (second attempt in three patients). In one patient, sufficient ventilation was not possible. In this case and in another patient with sufficient ventilation but estimated duration of surgery >3 h, endotracheal intubation was performed. Average time until first tidal volume was 17.3 seconds, ventilation was performed for 74 minutes. Pulse oximetric oxygen saturation was > or =97% at all times. Auscultation over the stomach was negative in all patients with an average cuff pressure of 73.7 cm H(2)O. During controlled ventilation aiming at an end tidal CO(2) of 35 mmHg (average 36.3 mmHg), an average tidal volume of 579 ml was reached, resulting in an inspiratory peak pressure of 20.2 cm H(2)O. Minimal traces of blood on the LTS were found in 5 patients, hoarseness was present in one patient after 6 hours, soar throat was stated after 1 hour by one patient (VAS 3), after 6 hours by 6 (average VAS 2.7) and after 24 hours by 3 patients (VAS 1.3). CONCLUSIONS: The LTS can be used for ventilation during elective surgery and can be placed with a high success rate. Postoperative complaints are infrequent and mild.

[Prehospital use of hypertonic solutions for traumatic brain injury]. / Präklinische Anwendungsmöglichkeiten hypertoner Infusionslösungen bei Patienten mit Schädel-Hirn-Trauma.

Hypertonic solutions efficaciously lower increased intracranial pressure and improve cerebral hemodynamics in particular at the level of microcirculation. Therefore hypertonic solutions have been introduced to the in-hospital intensive care treatment of brain-injured patients. In view of the disturbed cerebral perfusion and oxygenation in the acute phase following traumatic brain injury, early initiation of treatment is desirable to improve long-term outcome and to minimize secondary brain damage. Two different hypertonic isooncotic solutions are licensed in Germany for prehospital and in-hospital treatment of acute hypotension due to hypovolaemia and haemorrhagic shock. Both solutions offer interesting therapeutic options for treatment of patients with increased intracranial pressure. Limitation of license to the treatment of shock in Germany does not allow routine prehospital use in isolated head trauma at the moment. In other European countries, the approval for the prehospital use of hypertonic isooncotic solutions has been modified.

[Comparison of different laryngeal mask airways in a resuscitation model]. / Vergleich verschiedener Larynxmasken am Reanimationsmodell.

OBJECTIVE: The standard laryngeal mask airway LMA-Classic is recommended in the ILCOR guidelines as alternative to facemask and tracheal tube during cardiopulmonary resuscitation. LMA-Unique, LMA-Fastrach and LMA-ProSeal are additional variants that are compared with the standard LMA in a resuscitation model. METHODS: Tidal volumes, chest compressions and signs of gastric inflation are measured in a standardized resuscitation model (Ambu Cardiac Care Trainer with notebook and thumper). Ten 3-minute resuscitation cycles were performed with facemask and all LMAs (Classic, Unique, Fastrach, ProSeal, all size 4) with a ventilation : compression ratio of 2:15. To allow comparison with tracheal tube and to judge safety margins, another ten resuscitation cycles were performed with tracheal tube and all laryngeal masks with continuous chest compressions after two initial ventilations. The bag-valve device used for ventilation was replaced by an automatic transport ventilator in a third series with continuous chest compressions. Cuff pressures were set at 80 cm H2O. RESULTS: During interrupted chest compressions, adequate ventilation was possible with all devices. Tidal volumes for facemask, LMA-Fastrach and LMA-ProSeal were significantly (p < 0.001) higher than with LMA- Classic and LMA-Unique. During continuous chest compressions, significant differences (p < 0.001) occurred when comparing tracheal tube, Fastrach and ProSeal with the other two laryngeal mask airways, which did not reach recommended tidal volumes. During ventilation with the automatic transport ventilator, values for all devices except LMA-ProSeal dropped significantly, adequate ventilation was possible with tracheal tube, Fastrach and ProSeal. Signs of gastric inflation were found during ventilation with facemask and - to a lesser extent - with LMA-Classic. CONCLUSION: In the resuscitation model chosen, all laryngeal mask airways are possible alternatives for ventilation during cardiopulmonary resuscitation. The new LMA-ProSeal and also the LMA-Fastrach allow higher tidal volumes even during elevated intrathoracic pressures caused by continuous chest compressions, performing superior to the standard laryngeal mask airway. For inclusion of these devices in the ILCOR guidelines, further research in patients is warranted.

[Equipment of physician-staffed ambulance systems in the state of Baden-Wuerttemberg]. / Ausstattung von Notarztbesetzten Rettungsmitteln in Baden-Württemberg.

BACKGROUND: Laws regulating emergency medical systems in the federal state of Baden-Wuerttemberg call for equipment of physician-staffed ambulances that is based on current knowledge in emergency medicine. The grade of implementation is determined using single issue complexes. METHODS: A total of 127 emergency physician bases were located and each received a questionnaire regarding the equipment of the physician-staffed ambulances and helicopters and planned supplementation of the equipment, deadline was 30 June 2001. RESULTS: Of the 127 stations 116 (91.3%) participated. A 12-lead ECG is available in 52.6%, out-of-hospital fibrinolysis is possible in 15 bases (12.9%). Alternatives to endotracheal intubation are carried in 53.3% (cricothyroidotomy: 83.3%) and 31 bases provide capnometry or other devices for verifying correct tube placement. A mobile phone is available in 88 bases (75.9%). CONCLUSIONS: When comparing equipment of physician-staffed ambulances statewide, striking differences can be found.

Predominant involvement of motor fibres in patients with critical illness polyneuropathy.

Critical illness polyneuropathy (CIP) is a recognized cause of muscle weakness and failure of weaning from a ventilator. In order to characterize the features of CIP, we have examined 28 consecutive surgical patients with severe sepsis using bedside electrophysiology. Of the 28 patients (median APACHE II score 31), 20 developed moderate to severe CIP, as shown by the presence of moderate to severe denervation activity on resting EMG. The median nerve compound muscle action potential (CMAP) amplitudes were reduced to 3.24 (SEM 0.48) mV, while sensory nerve action potential (SNAP) amplitudes obtained from the same nerve were normal (13.1 (1.9) microV). In approximately 50% of these patients, the reduction in CMAP exceeded 50% of the lower limit of normal. Similar results were obtained from stimulation of the ulnar nerve. We conclude that CIP is a major complication in patients with severe sepsis and prolonged artificial ventilation. It predominantly involves motor fibres and thus markedly interferes with weaning from the ventilator.