[Intubation-linked dental injuries. Relevance of individually adaptable tooth protection models]. / Intubationsbedingte Zahnverletzungen. Wertigkeit individuell adaptierbarer Zahnschutzmodelle.

BACKGROUND: Tooth damage during anaesthesia could be reduced by using tooth protectors during endotracheal intubation. The effectiveness of different models was investigated using an upper jaw model. METHOD: A total of 6 individual adaptable dental protectors (Endoragard and Camo, with wax or silicone filling, respectively, Beauty pink dental wax with and without tissue inserts) were examined in three different categories. The upper jaw was covered with each dental shield and then loaded with a force of 150 N via a blade of a laryngoscope. Subsequently, force reduction was measured in axial as well as horizontal directions. Furthermore, the reduction in oral view was determined by measuring the thickness of each dental shield with a micrometer. RESULTS: The combination of Camo and silicone achieved the maximum horizontal force reduction value (39.2 N). Endoragard and silicone achieved the best axial value (21.6 N). Beauty pink wax had the thinnest dental shield (2.8 mm), whereas the combination of Camo and silicone gave the most limited view inside the oral cavity (3.8 mm). CONCLUSION: Preformed dental shields are useful for reducing the force applied to the teeth and potentially reducing the probability of tooth damage during laryngoscopy. However, the shield with the highest force reduction capability is relatively large and expensive which makes general use almost impossible. The model Beauty pink was slightly less force reducing and could be considered as an inexpensive and yet effective tool for clinical assignment.

The 'heparin lock': cause for iatrogenic coagulopathy.

BACKGROUND AND OBJECTIVE: The reasons for coagulopathy may be multiple and the identification of the underlying cause is often difficult. Recently, we identified two patients showing characteristics of heparin overdose during surgery. We hypothesised that filling a Shaldon dialysis catheter with heparin prior to closure, so-called heparin lock, might have triggered this coagulation disorder. Therefore, the aim of this in vitro study was to show whether this procedure can lead to an iatrogenic administration of heparin. METHODS: A Shaldon catheter (GamCath; Joka Kathetertechnik, Hechingen, Germany) was hung up in a container filled with NaCl solution 0.9% 5 mL and a heparin lock was simulated. Instead of using heparin solution we injected 1 mL of a KCl solution (1 mol L(-1)) into the Shaldon catheter, because the measurement of the potassium concentration is faster and more reliable than that of heparin. Ten measurements were taken after fast (0.5 s) and slow (3 s) injection speeds. RESULTS: Although the catheter volume is specified as 1.07 mL, an amount up to 0.51 mL KCl solution on average was detectable in the solution after locking the catheter with 1 mL KCl solution. CONCLUSIONS: Following a heparin lock a considerable amount of the injected solution is accidentally administered to the patient. Only 49.1% of the injected volume may remain in the Shaldon catheter. This could lead to an increased risk of coagulopathy.

[Does chewing gum have consequences for anesthesia? A case report]. / Hat Kaugummi eine Bedeutung für die Anästhesie?

Chewing gum is a common habit. Based on two cases of esophageal obstruction during induction of general anesthesia, the importance of chewing gum for anesthesiology is outlined. The dangers of chewing gum result from obstruction of the trachea and oesophagus but complications may also result from stimulated production of gastric juice with a risk of consecutive regurgitation and aspiration. In the case of an obstacle in the oesophagus when inserting a nasogastric tube, an obstruction by a mass of chewing gum should be considered. Although the literature provides differing statements concerning the volume and acidity of gastric juice after chewing gum, the use of chewing gum should be included in preanesthetic NPO rules.

[Secondary lung surgery following contralateral pneumonectomy. Anaesthesiological considerations]. / Sekundäre Lungeneingriffe nach vorausgegangener kontralateraler Pneumonektomie. Anästhesiologische Aspekte.

Although there have been an increasing number of reports on secondary lung surgery following contralateral pneumonectomy in recent years, little information is available about the anaesthesiological management of these patients. We therefore report on a 58-year-old patient who had already undergone a left-sided pneumonectomy and now required a right-sided thoracotomy to remove a recurrent tumour in the right upper lobe. The patient received a total intravenous anaesthesia (propofol, fentanyl) combined with atracurium for muscle relaxation. Following the orotracheal intubation with a Woodbridge tube, the patient was ventilated with the high frequency jet ventilation technique. The jet stream was administered via a catheter placed in the tube. The arterial O(2) saturation during ventilation was always 100%, and arterial CO(2) partial pressure was also normal. No complications occurred during tumour resection from the right upper lobe, and the patient was transferred to the ICU with stable pulmonary and haemodynamic conditions. After 2 h of ventilation, the patient was extubated with a completely expanded lung. The postoperative recovery was uneventful. This case report shows that,presupposing a sufficient pulmonary capacity, secondary lung surgery in previously pneumonectomised patients is feasible without complications given an appropriate anaesthesiological management.

Accuracy of feedback-controlled oxygen delivery into a closed anaesthesia circuit for measurement of oxygen consumption.

BACKGROUND: Oxygen consumption (V*O2) is rarely measured during anaesthesia, probably because of technical difficulties. Theoretically, oxygen delivery into a closed anaesthesia circuit (V*O2-PF; PhysioFlex Draeger Medical Company, Germany) should measure V*O2. We aimed to measure V*O2-PF in vitro and in vivo. METHODS: Three sets of experiments were performed. V*O2-PF was assessed with five values of V*O2 (0-300 ml min(-1)) simulated by a calibrated lung model (V*O2-Model) at five values of FIO2 (0.25-0.85). The time taken for V*O2-PF to respond to changes in V*O2-Model gave a measure of dynamic performance. In six healthy anaesthetized dogs we compared V*O2-PF with V*O2 measured by the Fick method (V*O2-Fick) during ventilation with nine values of FIO2 (0.21-1.00). V*O2-PF and V*O2-Fick were also compared in three dogs when V*O2 was changed pharmacologically [102 (SD 14), 121 (17) and 200 (57) ml min(-1)]. In patients during surgery, we measured V*O2-PF and V*O2-Fick simultaneously after induction of anaesthesia (n=21) and during surgery (n=17) (FIO2 0.3-0.5). RESULTS: Compared with V*O2-Model, V*O2-PF values varied from time to time so that averaging over 10 min is recommended. Furthermore, at an FIO2 >0.8, V*O2-PF always overestimated V*O2. With FIO2 <0.8, averaged V*O2-PF corresponded to V*O2-Model and adapted rapidly to changes. Averaged V*O2-PF also corresponded to V*O2-Fick in dogs at FIO2 <0.8. V*O2 measured by the two methods gave similar results when V*O2 was changed pharmacologically. In contrast, V*O2-PF systematically overestimated V*O2-Fick in patients by 52 (SD 40) ml min-1 and this bias increased with smaller arteriovenous differences in oxygen content. CONCLUSION: V*O2-PF measures V*O2 adequately within specific conditions.

[Neuromuscular monitoring in a patient with hemiparesis. Resistance of the paralysed musculature to non-depolarising muscle relaxants]. / Neuromuskuläres Monitoring bei Patienten mit Hemiparese Resistenz der gelähmten Muskulatur gegenüber nichtdepolarisierender Muskelrelaxanzien.

The control of the neuromuscular blockade is part of the standard monitoring in general anaesthesia. However, the degree of blocking is affected by different disorders. We describe the neuromuscular monitoring in four patients suffering from central hemiplegia by stimulation of the ulnar nerve simultaneously on the paretic and the normal side. After application of non-depolarising muscle relaxants (Atracurium, Mivacurium, Rocuronium, Vecuronium) a resistance of the paretic extremity against the relaxant used was shown in all cases. A possible explanation for this observation is the spreading out of abnormal acetylcholine receptors over the surface of denervated muscle cells which could lead to a false estimation of the depth of the neuromuscular blockade. Therefore, in the clinical practice, neuromuscular monitoring must always be carried out on the normal extremity of the patient.

[Intraoperative hyperkalemia - initial sign of an incipient compartment syndrome?]. / Intraoperativer Kaliumanstieg - erstes Zeichen eines späteren Kompartmentsyndroms?

We report the case of a 50 years old male patient who underwent an elective resection of the rectum in the Lloyd-Davis-position. During the surgery, first endoscopically and then by open laparatomy, which lasted 7.5 hours and the following postoperative time, plasma potassium concentration continuously increased up to 6.7 mval/l. On the first postoperative day, a compartment syndrome of the right lower limb was diagnosed.

[Unilateral high-frequency jet ventilation supporting one-lung ventilation during thoracic surgical procedures]. / Einseitige High-Frequency-Jet-Ventilation als Ergänzung der Ein-Lungenbeatmung bei thoraxchirurgischen Eingriffen.

We report two cases where surgery on the right lung had to be performed for resection of a malignoma. In both cases, function of the left lung was severely restricted. In the first patient, the volume on this side was reduced by around 50% as the result of a recently performed upper lobe resection. In the second patient, perfusion of the left lung accounted for only 18% of the total lung perfusion. On the basis of these changes we considered conventional one-lung ventilation impracticable and performed surgery using differential lung ventilation. The dependent (left) lung was ventilated by intermittent positive pressure ventilation (IPPV), where the tidal volume in the first patient had to be reduced to 200 ml because of high airway pressures. Ventilation of the non-dependent (right) side was performed simultaneously in both patients by means of high frequency jet ventilation (HFJV). Under this procedure arterial O2 saturation ranged from 96 to 100%, and arterial CO2 partial pressure was 45 mmHg. Surgery was not hindered by ventilation, the postoperative progress was also without complications. The case reports show that with the help of the ventilation regime described (operated side: HFJV, non-operated side: IPPV) lung surgery can be successfully performed on patients who are unsuitable for conventional one-lung ventilation for functional reasons.

[Hiatal hernia and risk of aspiration in anesthesia induction]. / Die Hiatushernie und das Aspirationsrisiko bei Narkoseeinleitung.

Papers recently published in the literature have questioned whether residual gastric fluid volume at the time of induction is the most important risk factor for pulmonary aspiration. To estimate the risk, more factors than the gastric fluid volume have to be considered. Concomitant diseases such as the hiatal hernia must be considered. Pulmonary aspiration during induction of anaesthesia seems to be caused by a multifactorial process, which consists of gastric fluid volume, anaesthetic technique and concomitant disease. A fifty-year-old man was scheduled for elective cholecystectom. During induction, the patient surprisingly regurgitated and aspirated gastric fluid. Postoperatively, an additional barium-swallowing x-ray examination showed a hiatal hernia. This case report shows that patients who report heartburn in their case history should be prophylactically treated as endangered by aspiration, even when they are considered to have an empty stomach.

Water vapour in a closed anaesthesia circuit reduces degradation/adsorption of halothane by dried soda lime.

Dry lime causes a loss of volatile anaesthetics by degrading and adsorbing them. Degradation produces toxic substances and heat. Rehydration of lime stops degradation. If humidified breathing gases rehydrate lime, closed anaesthesia-circuits may reduce the loss of anaesthetics. To test this hypothesis we ventilated a reservoir bag with PhysioFlex-devices using fresh (F) and dried (D) soda lime both in the presence (+H) and absence (-H) of halothane. We measured halothane delivery, humidity, temperature, and lime weight. Halothane was lost for 13 min in D + H. Humidity increased steeper with fresh lime, whereas absorbent weight increased more with dried lime; halothane increased both variables (F + H: 99%, 8 g; F - H: 93%, 6 g; D + H: 58%, 17 g; D - H: 24%, 15 g). Surprisingly, temperature remained constant, probably because of the high gas flow (70 litres min-1) generated inside the Physioflex. These findings indicate rehydration of dried lime by humid gases and a rapid cessation of the loss of halothane in the PhysioFlex.

[Arterial air embolism as a complication of blunt thoracic trauma]. / Arterielle Luftembolie als Komplikation des stumpfen Thoraxtraumas.

Systemic air embolism is a dramatic event frequently resulting in death. The clinical manifestations are polymorphic and unspecific. We report a case of a systemic air embolism in a patient with lung contusion. We wish to arouse a sensibility for this clinical picture, which seems to be underestimated in its frequency and importance, and discuss concepts of mechanical ventilation in patients with blunt thoracic trauma.

Atracurium during thoracic surgery: impaired efficiency in septic processes.

OBJECTIVE: The aim of the study was to examine whether the neuromuscular blocking potency of atracurium changes in patients with a septic intrathoracic process. DESIGN: Prospective clinical study. SETTING: Community hospital. PARTICIPANTS: Thirty patients who underwent thoracic surgery for resection of a pulmonary carcinoma were examined. Fifteen patients showed typical signs of a concomitant bacterial superinfection (infection group), 15 age-matched patients without infection served as the control (no-infection) group. INTERVENTIONS: Relaxation was induced with atracurium, 0.6 mg/kg intravenously for intubation, followed by a continuous infusion to maintain a 90% neuromuscular blockade. Relaxometry was performed electromyographically using the Datex Relaxograph by stimulating the ulnar nerve next to the wrist. MEASUREMENTS AND MAIN RESULTS: The onset time was significantly longer (5.3 +/- 2.9 v 3.3 +/- 1.2 minutes; p < 0.05), and the recovery phase (DUR 10%) was significantly shorter (23.5 +/- 8.6 v 36.9 +/- 7.3 minutes; p < 0.001) in the infection group compared with the controls. The infusion rate within the first hour of continuous application was 77.4% higher in the infection group than in the control group (11.0 +/- 2.9 v 6.2 +/- 1.0 microg/kg/min; p < 0.001). CONCLUSION: The study showed that septic intrathoracic processes cause a clear reduction of the neuromuscular blocking potency of atracurium. To guarantee adequate muscle relaxation in such cases, precise neuromuscular monitoring is highly advisable.

[One-lung respiration in a nasally intubated patient using a single-lumen endobronchial tube]. / Ein-Lungenventilation bei einem nasal intubierten Patienten mit Hilfe eines einlumigen Endobronchialtubus.

We report the case of a 57-year-old patient who underwent a right-sided thoracotomy. The preoperative examination of the patient already revealed a clear diminution of the mouth opening (Mallampati class 4). Ventilation per mask following the induction of anaesthesia was unproblematic. As oral intubation with a double-lumen tube seemed to be impossible because of the difficult anatomic conditions, nasal intubation was carried out. For this we used a left-sided single-lumen endobronchial tube of Rüsch (size 8.0). The tube was inserted into the left mainstem bronchus using a fiberoptic bronchoscope. Intraoperatively we were able to ventilate exclusively the dependent left lung by inflating the bronchial cuff. The operation itself was performed on the collapsed right lung. At the end of the operation the right lung could be ventilated once again by deflating the bronchial cuff (tracheal cuff inflated). This example demonstrates that one-lung ventilation is possible even under difficult intubation conditions.

[Reduced neuromuscular blocking potency of atracurium in patients with purulent intrathoracic diseases]. / Verminderte Wirksamkeit von Atracurium bei Patienten mit intrathorakalem Eiterherd.

OBJECTIVE: Based on personal observations the neuromuscular blocking potency of atracurium was supposed to be diminished in purulent intrathoracic diseases. This hypothesis was tested in a prospective clinical trial. METHODS: 52 adult patients undergoing general anaesthesia (methohexitone, sufentanil, flunitrazepam, N2O, enflurane) for elective thoracic surgery were investigated. After the intubation dose of 0.6 mg/kg atracurium was applied continuously to maintain a 90% suppression of the evoked compound electromyogram. According to the intraoperatively established diagnosis patients were allocated to three categories: 1) non-malignant tumor as the control group (n = 15), 2) lung cancer (n = 22), 3) purulent intrathoracic process without tumor (n = 15). The groups were compared regarding onset time, DUR 10% and maintenance dose of atracurium. RESULTS: Patients with lung cancer did not differ significantly from the controls regarding efficiency of atracurium. In contrast, patients with a purulent intrathoracic process showed a significantly longer onset time (6.3 +/- 2.5 vs. 2.9 +/- 0.8 min, p < 0.001), and a significantly shorter DUR 10% (23 +/- 6 vs. 36 +/- 10 min, p < 0.001) compared to the control group. Mean infusion rate of atracurium to maintain a 90% suppression of the evoked compound electromyogram was significantly higher in patients with a purulent process compared to the controls (10.5 +/- 3.2 vs. 6.0 +/- 1.2 micrograms/kg.min, p < 0.001). CONCLUSION: Our results support the hypothesis that patients with a purulent intrathoracic disease show a clear reduction in neuromuscular blocking potency of atracurium.