[Evaluation of the new supraglottic airway devices Ambu AuraOnce and Intersurgical i-gel. Positioning, sealing, patient comfort and airway morbidity]. / Evaluation der neuen Kehlkopfmasken Ambu AuraOnce und Intersurgical i-gel: Platzierbarkeit, Dichtigkeit, Patientenkomfort und Atemwegsmorbidität.

BACKGROUND: Supraglottic airway devices (SGAD) have become more important in airway management over the past years and an objective comparison of the available devices is in order. METHODS: In a prospective study the four SGADs LMA-Classic(cLMA), LMA-ProSeal (PLMA), Ambu AuraOnce and Intersurgical i-gel were compared in groups of 40 patients in ambulatory surgery, with respect to the feasibility of positioning, leak tightness, patient comfort and airway morbidity. The seal test of the airway devices was carried out with a specially constructed pneumotachograph. RESULTS: Adequate placement on the first attempt was achieved in 92.5% with the cLMA, 85% with the PLMA, 92.5% with the AuraOnce and 82.5% with the i-gel (p>0.05). There were no clinically relevant differences in mean insertion times: cLMA 13.8 s (+/-3.4 s), PLMA 13 s (+/-3.2 s), AuraOnce 11.2 s (+/-2.7 s; p<0.05) and 13.9 s (+/-3.6 s) with the i-gel. A tight seal at a constant oropharyngeal pressure of 15 cmH(2)O was achieved in 85% of the cases (34 cases) with the cLMA, 90% (36 cases) with the PLMA, 97.5% (39 cases) with the AuraOnce and 72.5% (29 cases) with the i-gel (p<0.05). A tight seal at a constant oropharyngeal pressure of 20 cmH(2)O was seen in 62.5% with the cLMA, 60% with the PLMA, 67.5% with the AuraOnce and in 50% with the i-gel of the cases (p>0.05). Airway morbidity was not observed in any group. Significantly more patients complained of a sore throat after using the cLMA (p<0.05). CONCLUSION: The tested SGADs were comparable with regard to ease of insertion, insertion times and airway morbidity. Considering leak tightness and patient comfort the PLMA and the AuraOnce fared better with regard to tightness of seal and patient comfort.

[Measurement of water vapour pressure in the airways of mechanically ventilated patient using different types of humidifiers]. / Wassergehaltsmessungen im Tracheobronchialsystem beatmeter Patienten bei Verwendung unterschiedlicher Befeuchtersysteme*

UNLABELLED: AIM OF THE INVESTIGATION: To evaluate the performance of different types of humidifying systems (heat and moisture exchanger, HME, and heated humidifier, HH) in the tracheo bronchial airway system of intubated mechanically ventilated patients. METHODS: A heated and fast responding capacitive sensor with a time constant of 0,23 s was used to measure the water vapor pressure at different locations in the tracheo bronchial airway system of 12 patients after therapeutic bronchoscopy. The sensor was immersed in an airstream of app. 1 ml/s continuously sampled with a bronchoscope in which the working pipe and the handle have been equipped with a heating system to prevent condensation. The sampling positions were 3 cm distal of the bifurcation in the right main bronchus, 2 cm proximal of the bifurcation and at the tube connector respectively. RESULTS: Without any humidifying system there was a dramatic reduction of the climatisation index respectively increase of the pulmonary water loss index, most prominently visible at the tube connector. There were significant differences between different types of HME (Pall BB 100 vs. Medisize Hygrovent S) but no significant differences between the Hygrovent S and the HH Fisher & Paykel 630 set at 34 degrees C. In consideration of applied tidalvolumens between 550 and 950 ml, isothermic saturation has not been reached in close vicinity to the bifurcation. CONCLUSIONS: HME may differ substantially from one type to the other and should not be used as climatisation system without careful consideration of their performance data. Effective HME are equivalent to HH at 34 degrees C and may therefore also be used for long term ventilation.

Comparison of ventilatory and haemodynamic effects of BIPAP and S-IMV/PSV for postoperative short-term ventilation in patients after coronary artery bypass grafting.

The aim of the present multiple cross-over study was to compare the effects of biphasic positive airway pressure (BIPAP) ventilation with synchronized intermittent mandatory ventilation combined with pressure support ventilation (S-IMV/PSV) in sedated and awake patients after coronary artery bypass grafting (CABG) surgery. Twenty-four patients with no evidence of preoperative respiratory dysfunction and an uncomplicated intraoperative course were investigated. The patients were randomly assigned to one of two groups starting with either BIPAP or S-IMV/PSV mode. Haemodynamic measurements and blood gas analyses were performed during sedation with 2.0 mg kg(-1) h(-1) propofol in the primary mode, after switching to the alternative ventilatory mode, and in the primary mode again. The same sequence of measurements was repeated in awake patients who had reached extubation criteria. In awake patients, PSV was performed instead of S-IMV. Statistical analysis of data was performed using non-parametric tests. Inspiratory peak pressure increased significantly during S-IMV/PSV in sedated patients in both groups. Other ventilatory parameters did not differ significantly between BIPAP and S-IMV/PSV in both groups. Similarly, haemodynamic parameters and blood-gas analyses did not vary with the ventilatory mode. Our results demonstrate that BIPAP ventilation has comparable effects on haemodynamics and pulmonary gas exchange compared with S-IMV/PSV and PSV when used for short-term ventilatory support in patients after cardiac surgery.

[Emergency and intensive care medicine as an interdisciplinary training requirement]. / Notfall- und Intensivmedizin als interdisziplinäre Lehraufgabe.

While substantial and practical qualification for medical practice within the framework of emergency medical services have to be proven by an advanced training, there are no special training programs for in-hospital emergency situations. As in the emergency room a transparent in-hospital emergency management has to be established including definite competencies to avoid time delays and inadequate treatment due to disputes about competence. Especially surgical intensive care medicine is an interdisciplinary task, requiring the participation of the surgeon as a responsible partner. Thus, the physician working in ICUs needs professional qualification and specialized knowledge as well as marked competence to co-operate. In any case the final clinical responsibility has to be taken over by physicians who not only have performed their internship on a ICU but are highly qualified in the whole range of intensive care medicine including all topics required in advanced intensive care medicine curricula.

The influence of controlled mandatory ventilation (CMV), intermittent mandatory ventilation (IMV) and biphasic intermittent positive airway pressure (BIPAP) on duration of intubation and consumption of analgesics and sedatives. A prospective analysis in 596 patients following adult cardiac surgery.

The aim of the study was the determination of the influence of ventilation modes on the consumption of analgesics and sedatives, duration of intubation and pulmonary gas exchange. Assist/controlled mandatory ventilation (S-CMV, 123 patients), synchronized intermittent mandatory ventilation (S-IMV, 431 patients) and biphasic positive airway pressure ventilation (BIPAP, 42 patients) were compared in a prospective, controlled, open clinical trial over an 18-month period. Five hundred and ninety-six adult patients with normal pulmonary function before surgery and uneventful course following coronary artery bypass graft surgery were studied. Patients ventilated with BIPAP had a significantly shorter mean duration of intubation (10.1 h, P < 0.05) than patients treated with S-IMV (14.7 h) and S-CMV (13.2 h). In the S-CMV group, 39.9% of the patients required single or multiple doses of midazolam, but only 13.5% in the S-IMV group and 9.5% in the BIPAP group. The mean total amount of midazolam administered to these patients was significantly higher in the S-CMV group (8.8 mg) than in the S-IMV group (6.6 mg, P < 0.05) and in the BIPAP group (4.3 mg, P < 0.05). The consumption of pethidine and piritramide did not differ between S-CMV and S-IMV, but was significantly lower during BIPAP (P < 0.05). After extubation the patients' PaCO2 was highest in the S-CMV group. We conclude that ventilatory support with BIPAP reduces the consumption of analgesics and sedatives, and the duration of intubation. The possibility of unrestricted spontaneous breathing in all phases of the respiratory cycle is considered to be the reason. BIPAP seems to be an alternative to S-CMV and S-IMV in short-term ventilated patient.

[The comparative effectiveness of different infusion and blood warming methods]. / Experimentelle Untersuchung zur Effektivität verschiedener Infusions- und Blutwärme-verfahren.

UNLABELLED: Heat loses during surgery occur mainly to the environment and due to infusions and irrigations. Infusions given at room temperature account for a great deal of the total heat deficit during major operations, e.g., the infusion of 53 ml/kg 20 degrees C fluid leads to a loss of 1 degree C in mean body temperature. Hence, heating i.v. fluids will add to the effect of other measures aimed at reducing heat loss to the environment. We investigated the efficacy of different warming methods for i.v. fluids in an experimental model by measuring the temperature at the end of the delivery line. METHODS: The following in-line warmers were studied: Hotline HL-90 and System H-250/heat exchanger D-50 (Level 1 Technologies, Marshfield, USA), Astotherm IFT 260 (Stihler Elektronic GmbH, Stuttgart, Germany), RSLB 30 H Gamida (Productions Hospitalieres Francaises, Eaubonne, France), Bair Hugger 241/Modell 500 Prototype (Augustine Medical, Eden Prairie, USA). They were compared with pre-warming infusions (39 degrees C) only using the Clinitherm S (Labor Technik Barkey GmbH, Bielefeld, Germany) and pre-warming with "active insulation" of the delivery line using the Autotherm/Autoline system (Labor Technik Barkey GmbH, Bielefeld, Germany). We investigated the influence of four variables on the efficacy of warming: (1) flow rate (50-15,000 ml/h); (2) ambient temperature (20 degrees C and 25 degrees C); (3) infusion bag temperature (6 degrees C, 20 degrees C, and 39 degrees C); and (4) length of infusion system downstream from the heat exchanger. Fluid temperatures were measured using thermistors of 1 mm diameter (Modell YSI 520, Yellow Springs Instruments Co., Yellow Springs, USA) incorporated into 3-way stopcocks. Temperatures were recorded using Hellige temperature monitors (Hellige GmbH, Freiburg im Breisgau, Germany) and the signals were collected at 10 Hz through an AD converter and averaged over 1 min. Flows were calculated by timed collection into calibrated cylinders; 10 to 12 different flow rates were taken to define one temperature/ flow plot. Effective warming was defined as a temperature > 33 degrees C at the end of the infusion line. RESULTS: At high flow rates (> 2,500 ml/h) using 20 degrees C fluids at 20 degrees C ambient temperature, the H-250/D-50 system gave the highest temperatures throughout the range and showed effective warming from 1,300 ml/h on over the entire range tested (35 degrees C at 17,000 ml/h) compared to the RSLB 30 H Gamida system (3,000-18,000 ml/h) (Fig. 2). This difference in performance was almost abolished with fluids at 6 degrees C (Fig. 4). Similar efficacy could be reached by using prewarmed infusions that gave effective warming at > 2,000 ml/h and reached 39 degrees C at 13,000 ml/h. Prewarmed infusions could be used effectively down to > 80 ml/h applying "active insulation" (Autotherm/Autoline) to the whole infusion system. The Hotline HL-90 (50-4, 700 ml/h) appeared to be the most effective in-line warmer in the low (< 250 ml/h) and middle (250-2,500 ml/h) flow range, followed by the Astotherm IFT 260 (400-4,000 ml/h), but only if used with a length of 40 cm down-stream from the heat exchanger (Fig. 1). Increasing this distance to 145 cm markedly reduced its efficacy below the range of 2,000 ml/min (1,200- 3,000 ml/h) (Fig. 5). The Bair Hugger 241 Prototype showed a narrow effective range (700-1,300 ml/h) that could be extended beyond 1,300 ml/h by the use of prewarmed infusions (Figs. 1 and 3). The performance for 6 degrees C solutions and ambient temperatures of 25 degrees C are given in Fig. 4 and Table 1. CONCLUSIONS: The importance of infusion warming increases with the amount of fluid given.(ABSTRACT TRUNCATED)

[Is reduction of intraoperative heat loss and management of hypothermic patients with anesthetic gas climate control advisable? Heat and humidity exchangers vs. active humidifiers ina functional lung model]. / Reduction intraoperativer Wärmeverlusteund behandlung hypothermer patienten durch atemgas-klimatisierende Massnahmen? Wärme- und Feuchtigkeitstauscher vs. aktive Befeuchter im beatmeten Lungenmodell.

UNLABELLED: Heated humidifiers (HH) as well as heat and moisture exchangers (HME) are commonly used in intubated patients as air-conditioning devices to raise the moisture content of the air, thus preventing mucosal damage and heat loss resulting from ventilation with dry inspired gases. In contrary to HME, HH are able to add heat and moisture to the inspired air in surplus, which is often stressed as an advantage in warming hypothermic patients or reducing major heat losses, e.g., during long operations. The impact of air conditioning on the energy balance of man was calculated comparing HME and HH. METHODS: The efficiency of a HME (Medisize Hygrovent) and a HH (Fisher & Paykel MR 730) was evaluated in a mechanically ventilated lung model simulating the physiological heat and humidity conditions of the upper airways. The gas flow from the central supply was dry; the model temperature varied between 32 and 40 degrees C. By using a HH in the inspiratory limb, a circle system was simulated with water-saturated inspired air at room temperature. The water content of the ventilated air was determined at the tracheal tube connection using a fast, high-resolution humidity meter and was compared with the moisture return of the HME. The energy balance was calculated according to thermodynamic laws. RESULTS: Both HME and HH were able to create physiological heat and humidity conditions in the airways. With the normothermic patient model, the moisture return of the HME was equal to that of the HH set at 34 degrees C. Increasing the heating temperature resulted only in reduced water loss from the lung; heat and water input in the normothermic model was not possible. This was only effective with almost negligible amounts under hypothermic patient model conditions. DISCUSSION: The water content in the inspired and expired air is the most important parameter for estimating pulmonary heat loss in mechanically ventilated patients. In adults (minute volume approximately 71/min) the main fraction of pulmonary heat loss results from water evaporation from the airways (approximately 6 kcal/h), whereas the heat loss due to convection is negligible (approximately 1.2 kcal/h). In intubated patients ventilated with dry air, the heat loss increases to approximately 8 kcal/h due to greater water evaporation from the airways. Both HME and HH are able to reduce the pulmonary heat loss to 1-2 kcal/h. In normothermic as well as hypothermic patients, HH do not offer significant advantages in heat balance compared to effective HME. In conclusion, air conditioning in intubated patients is neither a powerful too for maintaining body temperature during long-lasting anaesthesia nor a sufficient method of warming hypothermic patients in intensive care units.

Oxygen cost of breathing for assisted spontaneous breathing modes: investigation into three states of pulmonary function.

OBJECTIVE: We investigated the effects of continuous positive airway pressure (CPAP) and pressure support ventilation (PSV) on the oxygen cost of breathing (VO2resp) for different states of pulmonary function. Additionally VO2resp was measured during spontaneous breathing. DESIGN: This was done in a controlled and prospective study. Ventilatory modes were applied randomly. SETTING: Measurements were performed in a quiet room on volunteers (VOL) and inpatients treated for chronic obstructive pulmonary disease (COPD). Post-operative patients after aortocoronary bypass surgery (ACB) were studied on the cardio-thoracic intensive care unit just before and after extubation. PATIENTS: Healthy volunteers (n = 14), postoperative patients after aorto-coronary bypass surgery (n = 15) and patients with COPD (n = 9, xFEV1 47.7%) were the objects of study. INTERVENTIONS: Demand flow CPAP (5 mbar) and PSV (7 mbar, PEEP 5 mbar), using the Hamilton Veolar ventilator, were investigated in comparison to spontaneous breathing. MEASUREMENTS AND RESULTS: VO2 was measured by a Datex Deltatrac metabolic monitor. VO2resp was calculated by subtraction of total oxygen uptake (VO2tot) in controlled mode ventilation (CMV) from that in the respective spontaneous breathing mode. For VOL and COPD patients who were not intubated, a CPAP facemask connected to a short 7.5 mm tube was used as connection to the ventilator. Breathing spontaneously under a canopy system VOL showed a VO2resp of 4.5 +/- 4.0% compared to 9.2 +/- 3.5% for ACB and 15.4 +/- 7.7% for COPD. CPAP changed the VO2resp to 7.8 +/- 3.9%, 12.0 +/- 4.0% and 9.1 +/- 3.6% respectively. PSV reduced the VO2resp to 7.9 +/- 3.8% in ACB and 7.7 +/- 5.5% in COPD. CONCLUSIONS: This investigation confirms findings that postoperative patients have a mild increase in VO2resp. COPD exhibit the highest increase in VO2resp. Tracheal tubes, masks and CPAP on a demand flow apparatus increases VO2resp in volunteers and postoperative patients after cardiac surgery. The same amount of CPAP in contrary reduces VO2resp in patients with COPD. Pressure support ventilation can offset the additional VO2resp induced by CPAP but at the same level does not further reduce VO2resp in COPD patients.

[Inadvertant intracardiac entrapment of a Swan-Ganz catheter]. / Unbeasbsichtigte intrakardiale Fixierung eines Swan-Ganz-Katheters.

A 58-year-old man, admitted with one-vessel coronary disease and aortic valve insufficiency, was scheduled for cardiac surgery. He underwent single coronary bypass grafting and aorta ascendens replacement by a composite graft. During surgery he was monitored by a Swan-Ganz catheter, which had been inserted uneventfully via the right internal jugular vein. Six hours after completion of surgery we were unable to remove this catheter. Fluoroscopy showed intracardiac entrapment of the catheter. Rethoractomy was performed, revealing entrapment by a suture. The purse-string suture was released, and the catheter was withdrawn without resistance.

Comparison of sufentanil-nitrous oxide anaesthesia with fentanyl-nitrous oxide anaesthesia in geriatric patients undergoing major abdominal surgery.

We have measured haemodynamic changes and plasma concentrations of catecholamines during sufentanil-nitrous oxide and fentanyl-nitrous oxide anaesthesia in a controlled, randomized, double-blind study of 20 geriatric patients (age 65-86 yr) undergoing major abdominal surgery. Fentanyl 7 micrograms kg-1 followed by infusion of 3 micrograms kg-1 h-1 was compared with sufentanil 1 micrograms kg-1 followed by 0.4 micrograms kg-1 h-1. The opioid was supplemented with 60-67% nitrous oxide in oxygen. Haemodynamic changes, plasma concentrations of catecholamines (by high pressure liquid chromatography) and opioids (by radioimmunoassay), and myocardial lactate extraction were measured in the awake state, and at defined times during anaesthesia and surgery. Haemodynamic state was stable during induction and tracheal intubation in both groups, while during stressful operative periods there were increases in mean arterial pressure (17% in the fentanyl group; 11% in the sufentanil group), heart rate (fentanyl 20%, sufentanil 14%) and plasma concentrations of catecholamines (adrenaline: fentanyl 316%, sufentanil 86%; noradrenaline: fentanyl 78%, sufentanil 186%) in both groups. Sufentanil was similar to fentanyl in attenuating the haemodynamic and hormonal responses to surgical stimulation. In two patients in the fentanyl group and three in the sufentanil group, myocardial lactate production was observed temporarily, indicating myocardial ischaemia caused by surgical stress.

[Propofol infusion for sedation in regional anesthesia. A comparison with midazolam]. / Propofol-Infusion zur Sedierung bei Regionalanästhesien. Ein Vergleich mit Midazolam.

50 non-premedicated ASA class I or II patients were allocated randomly into two groups and received either a variable infusion of propofol or midazolam for sedation during orthopaedic surgery with regional blockade. To achieve a well-sedated patient with eyes closed and able to follow commands, the dose requirements for propofol were 1.25 mg/kg +/- 0.5 as a loading dose followed by a mean infusion rate of 3.17 mg kg-1 h-1 +/- 1.4 and for midazolam 0.073 mg/kg +/-0.02 and 0.074 mg kg-1 h-1 +/- 0.14. Steady-state plasma concentrations of propofol averaged 1.23 micrograms/kg +/- 0.75 and of midazolam 134 ng/ml +/- 62. Recovery was significantly shorter for propofol: 3.42 +/- 2.5 versus 8.05 min +/6.2 for midazolam. Perioperative cooperation was similar in both groups providing good or excellent conditions in 76% with propofol and in 52% with midazolam. 2h after discontinuation of the infusion 92% of the propofol patients were alert, while 36% of the midazolam were sleeping again. Cardiovascular effects of both drugs were minimal; however significant respiratory depression and/or airway obstruction developed in both groups (propofol 48%, midazolam 52%) requiring therapeutic intervention. Additional undesirable effects were: severe cough (propofol 40%, midazolam 20%), inadvertent movements (propofol 36%, midazolam 24%), confusion (propofol 24%, midazolam 20%), euphoria (propofol 44%), pain on injection (propofol 32%). The results of the study indicate that both drugs are useful and controllable sedative agents for surgery under regional anaesthesia, provided that measures for continuous monitoring of respiration and emergency care are guaranteed.

[Myocardial metabolism as affected by propofol in geriatric patients. A comparison with etomidate]. / Myokardstoffwechsel unter Propofol bei geriatrischen Patienten. Ein Vergleich mit Etomidat.

This study was designed to compare the effects of propofol and etomidate on myocardial metabolism in elderly patients without clinical manifestations of heart failure or coronary artery disease. Twenty geriatric patients (age 65-82 years) scheduled to undergo elective major upper-abdominal surgery were studied and randomly allocated to two equal groups (propofol and etomidate). All patients were premedicated with piritramide, 7.5 mg, and promethazine, 25 mg, intramuscularly 1 h before arrival in the anesthesia room. Ten patients received propofol (1.5 mg/kg) for induction of anesthesia, followed by 10-min infusion of an induction dose; thereafter, anesthesia was maintained with a continuous infusion of 0.1 mg/kg per min. Ten patients received etomidate, 18 mg, for induction, followed by 2.4 mg/min for maintenance. Vecuronium was used for neuromuscular blockade. Cardiovascular dynamics were recorded while the patients were awake, 1-2 min after induction during apnoea, and 1, 5 and 30 min after tracheal intubation without surgical stimulation. Coronary blood flow (argon wash-in technique with sampling of blood from the coronary sinus), myocardial oxygen consumption and myocardial uptake of glucose, free fatty acids and lactate were determined in the awake state and 5 and 30 min after intubation. Arterial plasma concentrations of propofol (high-pressure liquid chromatography with fluorescence detection) and etomidate (gas chromatography) were measured every 5 min throughout the investigation period, which lasted 45 min. Overall mean plasma concentrations of propofol were 3.69 +/- 0.16 micrograms/ml and of etomidate 1.1 +/- 0.16 microgram/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of propofol on cardiovascular dynamics and coronary blood flow in geriatric patients. A comparison with etomidate.

The cardiovascular and myocardial effects of propofol and etomidate were studied in 20 geriatric patients (age 65-84 years) who underwent major upper abdominal surgery. Ten patients received propofol 1.5 mg/kg for induction of anaesthesia followed by a continuous infusion of 0.1 mg/kg/minute for maintenance; 10 patients received etomidate 18 mg for induction followed by 2.4 mg/minute for maintenance. Vecuronium was used for neuromuscular blockade. Cardiovascular dynamics were recorded in the awake state one minute after induction and 1, 5 and 30 minutes after tracheal intubation; coronary blood flow (argon wash-in) and myocardial oxygen consumption were determined in the awake state and 5 and 30 minutes after intubation. Both anaesthetics decreased systolic, diastolic and mean arterial pressures, heart rate and cardiac index to the same extent. Myocardial blood flow and oxygen consumption were also reduced in both groups due to a reduction in cardiac work. Tracheal intubation produced a marked increase in arterial pressure in the etomidate group, while haemodynamic changes were absent in the propofol group, Myocardial lactate production was not observed in either group 5 or 30 minutes after tracheal intubation.