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.

[Desflurane and isoflurane in minimal-flow anesthesia. Consumption and costs with forced fresh gas reduction]. / Desfluran und Isofluran bei Niedrigflussnarkosen. Verbrauch und Kosten bei forcierter Frischgasreduktion.

BACKGROUND: In the present investigation we compared the consumption of desflurane (DES) and isoflurane (ISO) using a standardized minimal-flow protocol with a forced reduction of the fresh gas flow (FGF). METHODS: 54 adult women were examined. After induction of anaesthesia a forced reduction of the FGF was started: 5 min 0.5 l/min O(2) + 1 l/min N(2)O, 10 min 0.5 l/min O(2) + 0.5 l/min N(2)O; finally 0.3 l/min O(2) + 0.2 l/min N(2)O up to the end of surgery. The consumption of DES/ISO was determined with a precision balance. RESULTS: In the DES group the uptake was around 0.3 vol-%, i.e. less than 8% of the target 2/3 MAC value was taken up. For ISO the uptake was around 0.25 vol-%, i.e. the uptake was approximately 30% of the target 2/3-MAC value. The DES consumption was after 60 min 17.0+/-1.1 g, 120 min--27.3+/-1.8 g and 180 min--36.5+/-1.7 g. ISO consumption was significantly lower: 7.6+/-0.8 g, 12.4+/-1.7 g and 15.5+/-1.6 g. The use of DES yielded higher costs, i.e. 2.28 EUR for 60 min, 3.63 EUR for 120 min and 4.97 EUR for 180 min. The consumption of the inhaled anaesthetics can be calculated as: DES (g)=4.84+0.184 x duration (min) (R(2)=0.981), ISO (g)=2.049+0.0826 x duration (R(2)=0.979). The costs are: DES (EUR)=0.85+0.0323 x duration (min); ISO (EUR)=0.19+0.0077 x duration (min). CONCLUSION: With a forced reduction of the FGF the DES consumption is still higher.

[Extravasal position of central venous catheters despite unsuspicious ECG-guidance]. / Extravasale Lage von zentralen Venenkathetern bei korrekter EKG-Ableitung.

OBJECTIVE: Does the electrocardiographic method for central venous catheter positioning distinguish between a correct intravasal and a malpositioned extravasal position? METHODS: 24 cardiac surgical patients were enrolled in this prospective observational study. In 18 patients the left, in another 6 patients the right internal jugular vein was cannulated. Using a J-wire within a triple-lumen catheter the amplitude of the P-wave was measured at 3 different intravasal sites: Intra-1: (intravasal baseline electrocardiogram), i. e. 10 cm marking of the catheter on skin level; Intra-2: clear rise of the P-wave amplitude upon further insertion of the catheter; Intra-3: maximum P-wave amplitude. At this position the control of the catheter tip was achieved by means of transoesophageal echocardiography (TOE). Intraoperatively, another J-wire within a triple-lumen catheter was placed by the heart surgeon on 3 extravasal sites and the ECG was recorded: Extra-1: extravasal at the left innominate vein above the pericardial reflection; Extra-2: extravasal on the superior vena cava below the pericardial reflection; Extra-A: extravasal on ascending aorta below the pericardial reflection. The catheter was suture fixed with its tip in position Intra-3. Post surgery a chest radiograph was taken. RESULTS: All catheter tips were visualised at the basis of the Crista terminals (border between right atrium and superior vena cava) by TOE control. The rise of the P wave amplitude at Intra-2, Extra-2 and Extra-A was highly significant compared to the base line at Intra-1 (Intra-1/Intra-2, Intra-1/Extra-2, Intra-1/Extra-A: p in each case < 0.001). The P wave amplitudes of the corresponding intra- and extravasal positions of the left innominate vein (Intra-1/Extra-1, n = 18, p = 0.096)) as well as those of the superior vena cava (Intra-2/Extra-2, n = 24, p = 0.859) did not differ. CONCLUSION: The electrocardiographic method can not differentiate between intra- and extravasal position of a central venous catheter, and thus, presumably fails to identify malpositioning as a result of vascular perforation.

ECG recording of central venous catheter misplaced in inferior thyroid artery.

A 71-year-old male patient with liver metastases secondary to rectal carcinoma was scheduled for hemi-hepatectomy. Two months earlier he had undergone subtotal resection of the thyroid gland. Prior to surgery, a triple-lumen catheter and an introducer sheath were introduced into the right internal jugular vein using a landmark technique. No problems occurred during insertion of the triple-lumen catheter, but resistance was noticed during insertion of the 8.5 FG introducer sheath. After placement of the introducer sheath, intra-arterial misplacement was confirmed using a pressure transducer. The opportunity was taken to record and compare intravascular ECG by the arterial and venous catheters before removal. No difference was noticed in the P-wave patterns; both showed a marked increase. Surgical exploration of the neck, recommended by the vascular surgeon consulted, showed that the carotid artery was not injured. The introducer sheath had completely punctured the right internal jugular vein and entered the inferior thyroid artery. A thrill was felt. The management of this case is discussed, with suggestions for best practice. Intravascular ECG was unhelpful in differentiating between venous and arterial placement of the catheter.

[Acute liver failure. Current aspects of diagnosis and therapy]. / Akutes Leberversagen. Aktuelle Aspekte zur Diagnostik und Therapie.

Disturbances of some partial liver functions, such as synthesis, excretion, or biotransformation of xenobiotics, are important for prognosis and ultimate survival in patients presenting with multiple organ dysfunction on the intesive care unit (ICU). The incidence of liver dysfunction is underestimated when traditional "static" measures such as serum-transaminases or bilirubin as opposed to "dynamic" tests, such as clearance tests, are used to diagnose liver dysfunction. Similar to the central role of the failing liver in MODS, extrahepatic complications, such as hepatorenal syndrome and brain edema develop in acute or fulminant hepatic failure and determine the prognosis of the patient. This is reflected in the required presence of hepatic encephalopathy in addition to hyperbilirubinemia and coagulopathy for the diagnosis of acute liver failure. In addition to these clinical signs, dynamic tests, such as indocyanine green clearance, which is available at the bed-side, are useful for the monitoring of perfusion and global liver function. In addition to specific and causal therapeutic interventions, e.g. N-acetylcysteine for paracetamol poisoning or termination of pregnancy for the HELLP-syndrome, new therapeutic measures, e.g. terlipressin/albumin or albumin dialysis are likely to improve the poor prognosis of acute-on-chronic liver failure. Nevertheless, liver transplantation remains the treatment of choice for fulminant hepatic failure when the expected survival is <20%.

Kupffer cells and neutrophils as paracrine regulators of the heme oxygenase-1 gene in hepatocytes after hemorrhagic shock.

Heme oxygenase (HO) plays a pivotal role for the maintenance of liver blood flow and hepatocellular integrity after hemorrhagic shock. We investigated the role of Kupffer cells and neutrophils as paracrine modulators of hepatocellular HO-1 gene expression in a rat model of hemorrhage and resuscitation. Male Sprague-Dawley rats (n = 6-10/group) were anesthetized (pentobarbital, 50 mg/kg intraperitonal) and subjected to hemorrhagic shock (mean arterial blood pressure: 35 mmHg for 60 min) or a sham protocol. Based on the time course of HO-1 gene expression, the effect of various antioxidants, Kupffer cell blockade [gadolinium chloride (GdCl3); 10 mg/kg; 24 h prior to hemorrhage or dichloromethylene diphosphonate (Cl2MDP); 1 mg/kg; 2 days prior to hemorrhage], or neutrophil depletion (vinblastine, 0.5 mg/kg, 5 days prior to hemorrhage) on induction of the HO-1 gene was assessed at 5 h of resuscitation, i.e., the time point of maximal induction. Kupffer cell blockade and antioxidants abolished HO-1 mRNA and protein induction after hemorrhage, while neutrophil depletion failed to affect hepatocellular HO-1 gene expression. In addition, Kupffer cell blockade aggravated hepatocellular injury. N-formyl-methionine-leucyl-phenylalanin (fMLP) induced a substantial influx of neutrophils into the liver but failed to induce hepatocellular HO-1 mRNA expression. These data suggest that Kupffer cells but not neutrophils induce an adaptive hepatocellular stress response after hemorrhage and resuscitation. Oxygen-free radicals released by Kupffer cells may serve as paracrine regulators of a hepatocellular stress gene which is necessary to maintain liver blood flow and integrity under stress conditions.

The influence of resuscitation on hemodynamics and oxygen radical-induced reperfusion injury after arterialized liver transplantation in the rat.

Extended hemodynamic monitoring during arterialized rat liver transplantation procedure and the effects of resuscitation with albumin, starch-desferrioxamine-conjugated hydroxyethyl starch (HES-DFO), or hydroxyethyl starch (HES) on hemodynamics are presented. Livers from SPRD rats were stored for 20 hr in ice-cold UW solution and were orthotopically transplanted with reconstruction of the hepatic artery under hemodynamical monitoring applying invasive measurement of mean arterial blood pressure (MAP) and cardiac output (CO). Comparable amounts of albumin, HES-DFO, and HES were given in a randomized and blinded fashion after transplantation. Ringer's solution was given additionally when blood pressure was below 65 mmHg. Fifteen, 60, and 90 min after surgical procedure blood samples were taken to determine acid base status, blood gases, and blood cell count. Oxygen radical-induced reperfusion injury was determined by thiobarbituric acid reactive substances (TBARS) in serum and total glutathione in liver tissue 90 min after surgery. During the anhepatic period CO was reduced to 20% of baseline and MAP to 40 mmHg. In all groups, declamping led to a transient recovery of hemodynamic situation, whereas during further reperfusion, CO and MAP were significantly reduced in the HES- and HES-DFO-treated group in contrast to the group receiving albumin. Animals of the HES group required significantly more Ringer's solution to maintain blood pressure (2.6 +/- 0.9 ml; 4 of 6 animals needed additional resuscitation) than animals given albumin (0.4 +/- 0.3 ml, P < 0.05, 2/9 needed further supplementation) or HES-DFO (1.2 +/- 0.5 ml; 5/10 required additional resuscitation), respectively. Animals treated with HES or HES-DFO failed to restore base excess and serum lactate in contrast to resuscitation with albumin. However, TBARS was mitigated by resuscitation with HES-DFO compared to albumin and HES, whereas no significant differences were observed in respect to tissue glutathione of transplanted livers. In conclusion the model described allows intensive monitoring of hemodynamic parameters and metabolic status during arterialized rat liver transplantation procedure. Moreover, the results indicate that resuscitation with albumin could maintain central hemodynamics and restore homeostasis during the early reperfusion period after transplantation in contrast to resuscitation with HES or HES-DFO, respectively. Although resuscitation with HES-DFO resulted in mitigation of lipid peroxides determined by TBARS, no significant improvement of hemodynamics and homeostasis could be observed during reperfusion as it can be observed with albumin.