A. Donner

Indocyanine green video angiographies help to identify burns requiring operation

The key decision in the treatment of thermal injuries is the determination of the depth of the burn wound and the resultant decision on treatment options. The trend in the treatment of deep dermal and full thickness burns is toward very early excision and grafting to reduce the risk of infection, decrease scar formation, shorten hospital stay, and thereby reducing costs. Traditionally, this has involved serial clinical examinations, which involves primarily subjective judgment. Various objective examination techniques, supplementing the clinical diagnosis, have been suggested, but none has yet achieved widespread clinical acceptance. It has frequently been postulated that the blood flow in injured tissue indicates the extent of tissue damage. In this study, the clinical and scientific impact of indocyanine green (ICG) video angiography was tested in 20 patients. A wide range of depth of injury and etiology was included and analyzed. In all cases considered, video angiography was possible. The measurements and observations correlated well with the actual burn depth, which was assessed clinically (pre- and intraoperative assessment) and histologically (biopsies). In conclusion, ICG video angiography seems to be a practical method to describe vascular patency in a burn wound. The results indicate that ICG fluorescence angiography is a practical, accurate, and effective adjunct to clinical methods for estimating burn wound depth and thereby to assist in the rational assessment of treatment options. Furthermore, it allows an objective, qualitative and quantitative observation of the dynamic changes in burn wound depth, which are observed during the acute post-burn period, thereby indicating optimal timing of the first operation.

Propofol without muscle relaxants for conventional or fiberoptic nasotracheal intubation: a dose-finding study.

UNLABELLED Endotracheal intubation has been performed during the administration of propofol anesthesia without neuromuscular blockade. In this study, we determined the propofol dose required for conventional nasotracheal or for fiberoptic nasotracheal intubation of all patients. Thirty-two patients undergoing maxillofacial surgery were randomly assigned to the conventional (n = 16) or to the fiberoptic (n = 16) intubation group. In both groups, anesthesia was induced by using IV fentanyl and IV titrated propofol according to clinical need (spontaneous respiration rate, verbal response). An endotracheal tube was placed nasally in the pharynx and the vocal cords visualized by using a fiberscope inserted via the tube. In the conventional group, the larynx was visualized additionally with a laryngoscope blade (Miller). In both groups propofol was titrated until the vocal cords opened. Patients were tracheally intubated, and the propofol dose was recorded. In all patients, the trachea could be intubated without the use of muscle relaxants. Considerable interindividual differences of dose requirements were observed. The amount of propofol required in the conventional group was significantly (P < 0.0001) larger (median +/- SD: 2.74 +/- 1.59 mg/kg; range 1.95-7.07 mg/kg) than in the fiberoptic group (1.37 +/- 0.59 mg/kg; 0.72-2.86 mg/kg). Hemodynamics remained stable in all patients. Postintubational hoarseness occurred in three patients of each group. Fiberoptic nasal intubation without a muscle relaxant can be facilitated with significantly smaller and more predictable dosages of propofol than conventional nasal endotracheal intubation. The possibility of titrating the propofol dose under assisted ventilation until the vocal cords open during fiberoptic nasotracheal intubation and the better predictability of the required dose favors the fiberoptic approach. IMPLICATIONS In this study, contrary to all preceding studies using predefined doses of propofol and opioids, we determined the minimal required propofol dose in combination with fentanyl for conventional or fiberoptic nasotracheal intubation without muscle relaxants.

Value of Flumazenil in Benzodiazepine Self-Poisoning

SummaryThe efficacy of the benzodiazepine-antagonist flumazenil (Ro 15-1788) was evaluated in 26 patients with coma due to benzodiazepine self poisoning, alone or in combination with alcohol or other psychoactive drugs. 77% of the patients responded to the administration of a mean dose of 1.73mg (range 0.2 to 8mg) with immediate awakening or an improvement of at least 2 coma grades. In the patients without response (n=3) or with minor improvement (n=3) other psychoactive drugs turned out to be predominantly responsible for their comatose state. Adverse effects offlumazenil treatment such as altered blood pressure or increased heart rate were observed, but were generally mild. An acute benzodiazepine withdrawal syndrome was seen in 2 cases. In conclusion, flumazenil proved to be effective in the treatment of severe benzodiazepine intoxication. Beyond that, in cases of mixed over dosage or initially unknown diagnosis the antidote assisted in the clarification of the clinical condition.

Hydrocortisone improved haemodynamics and fluid requirement in surviving but not non-surviving of severely burned patients

Recent studies have shown that administration of hydrocortisone may lead to a reduction of catecholamines and to an improved outcome in septic patients. However, there are no data on the use of hydrocortisone in burn patients although in these patients reduction of vasopressors might be even more crucial for outcome due to improvement of skin perfusion. This study presents the first results on the impact of hydrocortisone administration in norepinephrine dependent severely burned patients. In a prospective cohort study fourteen consecutive severely burned patients received, 12h after norepinephrine dependency, a hydrocortisone bolus of 100mg followed by 0.18mg/(kgh) hydrocortisone. The course of the necessary norepinephrine dose, as well as the fluid balance was documented 12h prior and after the first dosage of hydrocortisone. Statistical analysis showed an unexpected increase of the required norepinephrine dosage. A statistical post hoc evaluation of surviving and non-surviving patients revealed a significant increase of norepinephrine in non-survivors whereas in survivors it was possible to reduce norepinephrine significantly. Furthermore, the median fluid requirement of surviving patients could be significantly reduced whereas in the group of non-survivors there was no change of volume needed. Our data suggests that hydrocortisone might be useful in selected patients with severe burn injuries. However, patients not responding to hydrocortisone administrations seem to have a poor prognosis. Our findings are in contrast to previously published data on septic patients, in whom hydrocortisone administration resulted in a reduction of norepinephrine. In burned patients the severity of trauma seems to have more profound influence on the pathophysiological mechanism of sepsis. Due to the high number of non-responders, the potential immune suppression and impaired wound healing caused by the side effects of hydrocortisone, further selection criteria seem to be necessary. A short ACTH-test might be considered prior to hydrocortisone administration to select patients who might benefit from this therapy. In summary, further prospective controlled studies will be necessary to establish hydrocortisone in the routine therapy of severely burned patients.

Tubeless Laryngotracheal Surgery in Infants and Children via Jet Ventilation Laryngoscope

We present the first use of tubeless superimposed combined high‐ and low‐frequency jet ventilation (SHFJV) with a jet laryngoscope in laryngotracheal surgery in infants and children. Twenty‐eight patients underwent 53 operative procedures. The average age of the patients was 7.3 years. The most common diagnoses were laryngeal papillomatosis and subglottic stenosis. The duration of jet ventilation averaged 33 min. The gas exchange was sufficient in each case. The advantages of SHFJV in the surgery of the laryngotracheal area in infants and children are optimal view at the larynx and trachea, maximum space for the handling, application of the laser without risks, no time limitation, suitability for stenosis, and neither anesthetic nor surgical complications.

Strömungsverhalten des Atemgases bei superponierter Hochfrequenz-Jet-Ventilation (SHFJV) über das Jet-Laryngoskop

ZusammenfassungIn der laryngealen Chirurgie werden, um eine endotracheale Intubation zu vermeiden, schon seit Jahren routinemäßig hochfrequente Beatmungsformen eingesetzt. Wir haben in einer Weiterentwicklung dieser Beatmungstechnik eine hochfrequente mit einer normofrequenten Jet-Ventilation kombiniert und konnten mit dieser superponierten Hochfrequenz Jet-Ventilation (SHFJV) sehr gute klinische Ergebnisse erzielen. Ziel unserer Gasgeschwindigkeitsmessungen am Lungensimulator an definierten Meßstellen, die dem mikrolaryngealen Operationsgebiet und der Trachea entsprechen, war es, einen Hinweis auf den Wirkungsmechanismus der SHFJV zu erhalten. Es zeigte sich, daß die Superposition der beiden Jetgasströme in der Inspiration eine höhere Geschwindigkeit und dadurch eine Vergrößerung des Tidalvolumens und des Entrainments bewirkt. So ist eine Beatmung auch bei Vorliegen eines völlig offenen Systems möglich. In der Exspirationsphase wird die Geschwindigkeit des normofrequenten Gasstroms durch den entgegengerichteten hochfrequenten Gasstrom verringert und so ein positiver endexspiratorischer Druck aufgebaut. Die Pulsationen des hochfrequenten Strahls bewirken eine permanente Belüftung der Alveolen. Die Anordnung der Düsen im Jet-Laryngoskop führt dazu, daß bereits an der Rohrspitze keine hohen Strahlgeschwindigkeiten mehr vorliegen und diese mit zunehmender Entfernung von den Düsen weiter abnehmen. Dadurch werden Schäden an der Larynxschleimhaut vermieden.AbstractHigh-frequency ventilation techniques have been applied for a number of years for laryngeal surgery in order to ventilate patients without endotracheal tubes or catheters. A further development of high-frequency jet ventilation (HFJV) is the technique of superimposed HFJV (SHFJV), which was achieved by combining low- and high-frequency jet streams. Although good clinical results were observed, which have been published in the past, the clinical details of development of SHFJV have not been previously published. Methods. In order to understand and study the mechanism of superimposition of a high-frequency jet stream, extensive experiments on a lung simulator at defined measuring points, which represented the operating field in microlaryngeal surgery and the trachea, were conducted prior to the clinical application of SHFJV. Results. The measurements demonstrated that superposition of the two jet streams led to greater velocity during inspiration, and therefore produced an increase in tidal volume and entrainment of inspiratory gas. This demonstrates that it is possible to apply a HFJV technique in patients even with an open system. During expiration, the velocity of the low-frequency gas stream is decreased by the opposing flow of the high-frequency jet stream, leading to the buildup of positive end-expiratory pressure. The pulsations of the high-frequency jet stream induce continuous alveolar ventilation. The positioning of the jet nozzles in the jet laryngoscopy has the result that the velocities are already decreased at the tip of the laryngoscope and decrease further with distance from the nozzles. This prevents possible damage to the laryngeal mucosa.

Superponierte Hochfrequenz Jetventilation (SHFJV) unter Verwendung von NO

ZusammenfassungDa trotz ständiger Fortschritte in der Intensivmedizin die Mortalität von Patienten mit ARDS immer noch über 50% liegt, kommen in der letzten Zeit verstärkt alternative Therapieverfahren zur Anwendung. Wir haben aus pathophysiologischen Überlegungen heraus versucht, zwei alternative Verfahren, nämlich die Beatmung mit NO und die superponierte Hochfrequenz Jetventilation (SHFJV) miteinander zu kombinieren. In experimentellen Untersuchungen am Lungensimulator wurde zunächst nachgewiesen, daß unter SHFJV bei allen Geräteeinstellungen eine exakte Zudosierung von NO in jeder gewünschten Konzentration unter Verwendung des „Pulmonox“ möglich ist. Bei einem Sollwert von 20 ppm NO lagen die tatsächlich gemessenen Werte zwischen 18 und 22 ppm. Anschließend wurde das kombinierte Therapieverfahren erstmals klinisch bei einem Patienten mit präfinalem ARDS als ultima ratio eingesetzt. Es kam zu einer deutlichen Verbesserung der Oxygenierung (paO2stieg bei gleicher FIO2von 1,0 von 69,4 mmHg unter konventioneller Beatmung nach 30 min SHFJV mit 20 ppm NO auf 289,9 mm Hg an, die periphere Sauerstoffsättigung stieg von 88,3 auf 99,5% an). Die hämodynamischen Parameter zeigten keine Unterschiede zwischen den beiden Beatmungsformen. Der Patient starb trotz Verbesserung der pulmonalen Situation an einem therapieresistenten hämodynamischen Versagen. Es bleibt in weiteren Studien abzuklären, ob der Erfolg dieser Beatmungsstrategie reproduzierbar ist, und ob die Oxygenierung bei Kombination von SHFJV und NO besser als bei getrenntem Einsatz der beiden Maßnahmen.AbstractThe mortality of patients with acute respiratory distress syndrome (ARDS) is still above 50% despite continuous progress in intensive care medicine. Recent therapy regimens such as the extra corporeal life support (ECLS), permissive hypercarbia, high-frequency ventilation techniques and inhaled nitric oxide (NO) are being applied. All of the above techniques are aimed at different parts of the problems caused by ARDS. This study was designed to evaluate the possible additive benefits of superimposed high-frequency jet ventilation (SHFJV) and inhaled NO. Methods. In experiments on a lung simulator it was demonstrated that it is possible to administer exact amounts of NO using a computer-controlled system with a feedback loop (Pulmonox) using the SHFJV. Applying the therapeutic reference point of 20 ppm of NO, the deviation was ±3 ppm at this setting. Case report. After successfully concluding our experiments, this combined therapy concept was applied in a patient with terminal ARDS. Under CMV, paO2 was 69.4 mm Hg and the oxygen saturation 88.3% with a FIO2 of 1.0. Significant improvement was observed within 30 min after starting SHFJV with inhaled NO (paO2 282.9 mm Hg; oxygen saturation 99.5%). There were no differences observed in hemodynamic parameters between CMV and SHFJV. Although the pulmonary status of the patient improved, the patient died due to therapy-resistant hemodynamic failure. Conclusion. It will take further studies to judge whether the success of this new ventilation strategy is reproducible and if the improvement of the oxygenation is more pronounced when adding inhaled NO to SHFJV than when each technique is applied separately.

SHFJV : Jet-Adapter zur Durchführung der Superponierten Hochfrequenz Jet-Ventilation (SHFJV) über einen Tubus in der Intensivmedizin : Eine technische Neuerung

ZusammenfassungDie superponierte Hochfrequenz Jet-Ventilation (SHFJV) wurde als alternative Beatmungstechnik bei Patienten mit Lungenversagen eingesetzt. Um diese Beatmungsform optimal applizieren zu können, wurde ein spezieller Jet-Adapter entwickelt. Methoden: Dieser Jet-Adapter aus Kunststoff besteht aus einem T-Stück mit vier Kunststoffkanülen und kann an jeden handelsüblichen Endotrachealtubus konnektiert werden. Eine Umintubation auf einen speziellen Jet-Tubus vor dem Beginn der SHFJV ist unnötig. Die simultane hoch- und niederfrequente Beatmung erfolgt über zwei Düsen. Zwei weitere Kanülen dienen der kontinuierlichen Messung des Beatmungsdrucks und der Befeuchtung des Atemgases. Über den Querschenkel des T-Stücks wird ein Atemgasquerstrom geleitet. Eine zusätzliche, verschließbare Öffnung im Querschenkel des T-Stücks ermöglicht das Einführen eines Absaugkatheters oder eines Bronchoskops, so daß keine Diskonnektion vom Respirator erforderlich ist. Ergebnisse: Mit dem Jet-Adapter kann 1. die SHFJV angewendet werden, 2. der Beatmungsdruck kontinuierlich gemessen werden, 3. die Befeuchtung und Erwärmung der Atemgase durchgeführt und 4. Medikamente appliziert oder NO zugeleitet werden Schlußfolgerung: Der Jet-Adapter gewährleistet mit der SHFJV eine suffiziente Beatmung, die mit anderen therapeutischen Möglichkeiten kombiniert werden kann.AbstractDespite advances and technical developments in the area of intensive care medicine is has not been possible to lower the mortality of patients with pulmonary insufficiency. Therefore, alternative ventilation strategies have been developed and applied. One of these ventilation techniques is superimposed high-frequency jet ventilation (SHFJV). For optimal application of SHFJV we designed a special jet-adapter. Methods: This jet-adapter made of plastic consists of a T-piece and four central, small-bore cannulas and can be connected to any commercially available endotracheal tube. Therefore, it does not require reintubation with an endotracheal jet tube when beginning SHFJV. The simultaneous high-frequency and low-frequency jet ventilation is performed over two jet-nozzles that have been designed according to optimal flow dynamic measurements. Two further cannulas are used for continuous airway pressure monitoring and humidification of the applied gases. A pre-warmed and humidified bias flow with exactly defined oxygen concentration is led through the cross-part of the T-piece for gas entrainment. Additionally, the cross-part contains a port that can be opened for endotracheal suctioning or bronchoscopy and makes disconnection of the jet adapter from the endotracheal tube for either purpose unnecessary. Conclusion: The jet adapter can be used: (1) to apply SHFJV; (2) to measure airway pressures continuously; (3) to humidify and warm inspired gases; (4) to administer medications or add nitrous oxide by the inspiratory route, enabling combination with new therapeutic possibilities in the management of patients with severe ARDS.

Erste Erfahrungen mit der Superponierten Hochfrequenz-Jetventilation in der Intensivmedizin

ZusammenfassungIn der vorliegenden Studie sollte untersucht werden, ob die Superponierte Hochfrequenz-Jetventilation (SHFJV) für den Einsatz in der Intensivmedizin bei Patienten mit Lungenversagen geeignet ist. Wir haben die Untersuchungen bei drei Patientenkollektiven durchgeführt: In Gruppe 1 waren lungengesunde Patienten, die aufgrund einer zerebralen Erkrankung beatmet werden mußten, in Gruppe 2 Patienten mit mäßiggradiger pulmonaler Symptomatik und in Gruppe 3 Patienten mit schwerem Lungenversagen zusammengefaßt. Bei den Patienten in Gruppe 1 und 2 wurde die konventionelle Beatmung intermittierend für jeweils 30 min von der SHFJV unterbrochen, die Patienten in Gruppe 3 wurden über 13 bis 53 h mittels SHFJV beatmet. Bezüglich Oxygenierung und Ventilation zeigten sich bei den Patienten in Gruppe 1 und 2 keine signifikanten Unterschiede zwischen den beiden Beatmungstechniken, der Atemwegsspitzendruck war unter SHFJV signifikant niedriger als unter konventioneller Beatmung (Pmax 12,9 vs 13,3, p<0,05). Bei den Patienten in Gruppe 3 war die Oxygenierung unter SHFJV bei signifikant niedrigerer FIO2 und signifikant niedrigeren Atemwegsdrucken signifikant besser (Pmax 29,6 vs. 40,1 mm Hg, mittlerer Paw 18 vs. 21,9 mm Hg, PaO2 140,1 vs. 109,9 mm Hg, FIO2 0,66 vs. 0,86, Mittelwerte, p<0,05), die Ventilation war gleich. Weiter zeigte sich eine signifikante Abnahme des intrapulmonalen Shunts (24,6 vs. 34,4, p<0,05). Wir glauben, daß die SHFJV, ähnlich wie die Beatmung mit NO oder die ECMO, einen Ansatzpunkt für die Beatmung von Patienten mit Lungenversagen, bei denen die Möglichkeiten einer konventionellen Beatmung ausgeschöpft sind, dargestellt.AbstractThe study aimed to evaluate whether superimposed high-frequency jet ventilation (SHFJV) is a useful tool in intensive care medicine to ventilate patients with pulmonary insufficiency. Methods. SHFJV is the simultaneous application of low- and high-frequency jet ventilation performed using a specially designed ventilator. SHFJV versus conventional mechanical ventilation (CMV) was were applied in three groups of patients. Group 1 (Gr 1) included patients without pulmonary insufficiency; group 2 (Gr 2) patients had moderate and those in group 3 (Gr 3) had severe pulmonary insufficiency. Results. In Gr 1 and Gr 2, SHFJV was associated with a significant decrease in mean airway pressure (mPAW 12.9 vs. 13.3 mm Hg, P<0.05). In Gr 3 oxygenation was significantly better with SHFJV (mean paO2 140.1 vs. 109.9 mm Hg, P<0.05; mean FiO2 0.66 vs. 0.86, P<0.05). Other parameters, such as maximum airway pressure (Pmax) and mean Paw, were significantly lower with SHFJV than CMV (mean Pmax 29.6 vs. 40.1 mm Hg, mean Paw 18 vs. 21.9 mm Hg, P<0.05). Intrapulmonary shunt fractions showed a significant decrease with SHFJV (24.6 vs. 34.4, P<0.05). Conclusions. Significant differences were observed primarily in Gr 3 patients, indicating that patients with severe pulmonary insufficiency may benefit from SHFJV. SHFJV may thus represent an alternative mode of ventilation in critically ill patients.

Laryngeal surgery by three-dimensional (3-D) endoscopy via the jet laryngoscope using superimposed high-frequency jet ventilation (SHFJV)

Zusammenfassung. Operationen in 3-D-Technik werden in der Abdominalchirurgie und in der Thoraxchirurgie bereits in Einzelfällen eingesetzt, in der mikrolaryngealen Chirurgie bislang aber noch nicht verwendet. Ein 3-D-Endoskop wurde durch das Jet-Laryngoskop eingeführt, und unter Beatmung mittels der superponierten Hochfrequenz-Jet-Ventilation (SHFJV) wurde das Druckverhalten an der Rohrspitze und intrapulmonal zunächst experimentell registriert und anschließend diese Technik klinisch bei 7 Patienten angewendet. Messungen am Lungensimulatur zeigten, daß es durch Einengung des Querschnitts des Jet-Laryngoskops zu einer Zunahme des exspiratorischen Widerstands und zu einer Zunahme des Tidalvolumens und des Beatmungsspitzendrucks kommt. Durch Reduktion des Arbeitsdrucks können der Ausgangsdruck und das ursprünglich eingestellte Tidalvolumen exakt beibehalten werden. In der klinischen Anwendung waren Beatmung, Inspektion und Operation durch das Jet-Laryngoskop bei allen Patienten problemlos möglich, der CO2-Laser konnte ohne Änderung des Beatmungsregimes eingesetzt werden. Obwohl für den Routineeinsatz im HNO-Bereich spezielle technische Veränderungen angestrebt werden müssen, konnte das 3-D-Endoskop in der vorliegenden Form in Verbindung mit der SHFJV bereits klinisch erprobt werden und bietet dem Operateur neue Möglichkeiten in der stimmverbessernden Larynxmikrochirurgie. Mittels SHFJV ist eine sichere Beatmung des Patienten möglich.Abstract. Surgery by three-dimensional (3D) endoscopy is being used routinely in abdominal surgery and, in special cases, in thoracic surgery; however, it has not been reported as being used in microlaryngeal surgery. Methods. We inserted a 3-D endoscope into a jet laryngoscope and studied the pressure properties at the tip of the laryngoscope as well as intrapulmonary pressures while applying superimposed high-frequency jet ventilation. The studies were conducted initially using a lung simulator, and then in seven patients undergoing microlaryngeal surgery. Results. Due to the rather large 3-D endoscope, the diameter of the jet laryngoscope was reduced by between 25.2% and 70.9%, depending on its size. The measurements on the lung simulator revealed that reduction of laryngoscope diameter leads to an increase in the following parameters: expiratory resistance, tidal volume, and peak inspiratory pressure. The mean FiO2 was 0.74±0.1; the mean paO2 was 169.2±80.4 mm Hg; and the mean paCO2 was 40.9±2.4 mm Hg. The mean airway pressure was 19±5.3 mm Hg prior to insertion of the endoscope and 12.3±6.9 mm Hg after insertion. The mean positive end-expiratory pressure values increased from 2±0.6 to 3.6±2.3 mm Hg. Reduction of the working pressure resulted in restoration of the initial inspiratory pressures and tidal volumes. Conclusions. In the clinical application of 3-D endoscopy via a jet laryngoscope, it was possible to achieve sufficient ventilation, inspection of the surgical field, and performance of the surgical procedure. A CO2 laser was used without changing the ventilation regime. Although technical alterations would be desirable for its application to microlaryngeal surgery, it is presently possible to safely use the 3-D endoscope via the jet laryngoscope for microlaryngeal surgery, presenting the surgeon with new possibilities in voice-improving microsurgery of the larynx.