[Optimal Postoperative Pain Management After Tonsillectomy: An Unsolved Problem]. / Optimale Schmerztherapie nach Tonsillektomie: ein ungelöstes Problem.

Tonsillectomy is one of the most painful surgical procedures. Unfortunately, it is not unusual that the patient hear statement like: "There is no way around" or "You receive already enough pain killers". Asking the anesthetist or the otorhinolaryngologist, one may get to hear: "Pain after tonsillectomy is not a real problem. We have a reliable pain management protocol". In contradiction, many clinical studies are showing that many patients have persistent and even severe pain after tonsillectomy despite postoperative pain therapy. Considering the results of many controlled clinical trials analyzing manifold varieties of pain management regimes it becomes obvious that there is no standard pain therapy after tonsillectomy with reliable proof of sufficient pain suppression. This review wants to give an overview on the current status of clinical research on pain measurement methods and pain management after tonsillectomy.

Transtracheal ventilation with a novel ejector-based device (Ventrain) in open, partly obstructed, or totally closed upper airways in pigs.

BACKGROUND: Transtracheal access and subsequent jet ventilation are among the last options in a 'cannot intubate-cannot oxygenate' scenario. These interventions may lead to hypercapnia, barotrauma, and haemodynamic failure in the event of an obstructed upper airway. The aim of the present study was to evaluate the efficacy and the haemodynamic effects of the Ventrain, a manually operated ventilation device that provides expiratory ventilation assistance. Transtracheal ventilation was carried out with the Ventrain in different airway scenarios in live pigs, and its performance was compared with a conventional jet ventilator. METHODS: Pigs with open, partly obstructed, or completely closed upper airways were transtracheally ventilated either with the Ventrain or by conventional jet ventilation. Airway pressures, haemodynamic parameters, and blood gases obtained in the different settings were compared. RESULTS: Mean (SD) alveolar minute ventilation as reflected by arterial partial pressure of CO2 was superior with the Ventrain in partly obstructed airways after 6 min in comparison with traditional manual jet ventilation [4.7 (0.19) compared with 7.1 (0.37) kPa], and this was also the case in all simulated airway conditions. At the same time, peak airway pressures were significantly lower and haemodynamic parameters were altered to a lesser extent with the Ventrain. CONCLUSIONS: The results of this study suggest that the Ventrain device can ensure sufficient oxygenation and ventilation through a small-bore transtracheal catheter when the airway is open, partly obstructed, or completely closed. Minute ventilation and avoidance of high airway pressures were superior in comparison with traditional hand-triggered jet ventilation, particularly in the event of complete upper airway obstruction.

Effects of arginine vasopressin on oxygenation and haemodynamics during one-lung ventilation in an animal model.

In a case of arterial hypotension during one-lung ventilation, haemodynamic support may be required to maintain adequate mean arterial pressure. Arginine vasopressin, a potent systemic vasoconstrictor with limited effects on the pulmonary artery pressure, has not been studied in this setting. Twelve female pigs were anaesthetised and ventilated and arterial, central venous and pulmonary artery catheters were inserted. A left-sided double lumen tube was placed via tracheostomy and one-lung ventilation was initiated. The animals were in the left lateral position, with the left lung ventilated and right lung collapsed. Respiratory and haemodynamic values were recorded before and during a continuous infusion of arginine vasopressin sufficient to double the mean arterial pressure. The arginine vasopressin caused a decrease in cardiac output (3.8+/-1.1 vs. 2.7+/-0.7 l/min, P <0.001) and mixed-venous oxygen tension (39.1+/-5.8 vs. 34.4+/-5 mmHg, P=0.003). Pulmonary artery pressure was unchanged (24+/-2 vs. 24+/-3 mmHg, P=0.682). There was no effect of the arginine vasopressin on arterial oxygen tension (226+/-106 vs. 231+/-118 mmHg, P=0.745). However, there was a significant decrease in shunt fraction (28.3+/-6.2 vs. 24.3+/-7.8%, P=0.043) and a significant proportional increase in perfusion of the ventilated lung (78.8+/-9.5 vs. 85.5+/-7.9%, P=0.036). In our animal model of one-lung ventilation, doubling mean arterial pressure by infusion of arginine vasopressin significantly affected global haemodynamics, but had no influence on systemic arterial oxygen tension.

[Preclinical transtracheal emergency ventilation. Animal experimental comparison of two techniques]. / Präklinische transtracheale Notfallventilation. Tierexperimenteller Vergleich zweier Techniken.

INTRODUCTION: Prehospital transtracheal ventilation via a needle cricothyroidotomy may be lifesaving in cannot-intubate-cannot-ventilate situations. A self-made device consisting of a three-way stopcock placed between a transtracheal airway catheter and an oxygen supply was constructed and the effectiveness of the device was compared with a hand-triggered emergency jet generator in animal experiments. MATERIALS AND METHODS: An emergency transtracheal airway catheter was inserted into the trachea of 10 anesthetized pigs (18-35 kgbw) and a situation of partial expiratory airway obstruction was established. All pigs were ventilated in a randomized order via the transtracheal airway catheter with the hand-triggered emergency jet injector and the self-made device for 15 min each. RESULTS: With both devices satisfactory oxygenation and ventilation was achieved in all animals. CONCLUSIONS: The efficacy of the self-made device during the experiment was comparable with the efficacy of the hand-triggered emergency jet injector.

The effects of increasing concentrations of isoflurane and desflurane on pulmonary perfusion and systemic oxygenation during one-lung ventilation in pigs.

UNLABELLED: During one-lung ventilation (OLV), hypoxic pulmonary vasoconstriction (HPV) reduces venous admixture and attenuates the decrease in arterial oxygen tension by diverting blood from the nonventilated lung to the ventilated lung. In vitro, desflurane and isoflurane depress HPV in a dose-dependent manner. Accordingly, we studied the effects of increasing concentrations of desflurane and isoflurane on pulmonary perfusion, shunt fraction, and PaO(2) during OLV in vivo. Fourteen pigs (30-42 kg) were anesthetized, tracheally intubated, and mechanically ventilated. After placement of femoral arterial and thermodilution pulmonary artery catheters, a left-sided double-lumen tube (DLT) was placed via tracheotomy. After DLT placement, FIO(2) was adjusted at 0.8 and anesthesia was continued in random order with 3 concentrations (0.5, 1.0, and 1.5 minimal alveolar concentrations) of either desflurane or isoflurane. Differential lung perfusion was measured with colored microspheres. All measurements were made after stabilization at each concentration. Whereas mixed venous PO(2), mean arterial pressure, cardiac output, nonventilated lung perfusion, and shunt fraction decreased in a dose-dependent manner, PaO(2) remained unchanged with increasing concentrations of desflurane and isoflurane during OLV. In conclusion, increasing concentration of desflurane and isoflurane did not impair oxygenation during OLV in pigs. IMPLICATIONS: In an animal model of one-lung ventilation, increasing concentrations of desflurane and isoflurane dose-dependently decreased shunt fraction and perfusion of the nonventilated lung and did not impair oxygenation. The decreases in shunt fraction are likely the result of anesthetic-induced marked decreases in cardiac output and mixed venous saturation.

Onset of neuromuscular block at the masseter and adductor pollicis muscles following rocuronium or succinylcholine.

PURPOSE: To compare the onset time of two different rocuronium doses (0.6 and 0.9 mg x kg(-1)) and succinylcholine (1.5 mg x kg(-1), preceeded by 0.06 mg x kg(-1) rocuronium) at the masseter and the adductor pollicis muscle. METHODS: In a randomized study, 60 ASA I or II adult women, 18-65 yr of age, were anesthetized with propofol and fentanyl and nitrous oxide in oxygen. Neuromuscular monitoring was performed using acceleromyography simultaneously on the masseter and adductor pollicis. Onset time was measured at both muscles using supramaximal 0.1 Hz single twitch stimulation (square-wave pulse 0.2 msec duration). RESULTS: In all patients, complete neuromuscular block occurred at the masseter and adductor pollicis muscles. Lag-time and onset time were faster at the masseter that at the adductor pollicis muscle in both rocuronium-groups (P < 0.01) and in the succinylcholine-group (P < 0.01). Furthermore, onset time was more rapid after 0.9 mg x kg(-1) rocuronium (65 +/- 7 s) than after succinylcholine (83 +/- 19 sec) at the AP (P < 0.05), but did not differ at the masseter (33 +/- 6 vs 36 +/- 7 sec). CONCLUSIONS: Following rocuronium and succinylcholine, onset time is faster at the masseter than at the adductor pollicis muscle.