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Biomedical subjects

J Rathgeber

Publications and source records attributed to J Rathgeber.

At least 37 records · Page 2Linked to original sources
PubMed1997

[Ventilation modes and strategies in intensive care medicine].

Advances in ventilator technology and recent findings in pathophysiological mechanisms have resulted in a remarkable decrease in classical volume controlled and pressure controlled ventilation modes as treatment for severe acute respiratory insufficiency. New modes of ventilatory support enabling and encouraging patients' spontaneous breathing, such as Biphasic Positive Airway Pressure (BIPAP) and Airway Pressure Release Ventilation (APRV), make it possible to adapt ventilatory support better and more easily to suit patients' needs than conventional modes of controlled ventilation. Preservation and support of patients' spontaneous breathing improves pulmonary gas exchange and reduces stress imposed by mechanical ventilation. The 'invasiveness' of mechanical ventilation is reduced and patients' comfort is less disturbed. Through this, the need for sedation and analgesia is considerably reduced and this may minimize systemic side-effects and complications from analgo-sedation and mechanical ventilation. The drugs should be administered in an adequate, individually adapted manner. Routinely-ordered and fixed combinations of drugs administered continuously are not adequate adequate as they further carry the risk of overdosing a different single drug with the corresponding side-effects (depression of respiratory drive, gut motility, etc.).

Procedural Sedation↗
PubMed1996

[Air conditioning with a high-performance HME (heat and moisture exchanger)--an effective and economical alternative to active humidifiers in ventilated patients. A prospective and randomized clinical study].

Heat and moisture exchangers (HME) are used as artificial noses for intubated patients to prevent damage resulting from dry and cold inspired gases. HME collect a large fraction of the heat and moisture of the expired air, adding them to the subsequent inspired breath. In a prospective clinical study the air conditioning capacity of a heated humidifier was compared with a hygroscopic HME. METHODS. The water content of the ventilated air of 49 intensive care patients requiring artificial ventilation with tidal volumes between 440 and 1,190 ml (mean 658 +/- 148 ml) was examined. Each patient was ventilated in sequence with an HME (DAR Hygrobac S) and a heated humidifier (Fisher & Paykel MR 630 B). The temperature of the air in the inspiratory limb was maintained at 34 degrees C. The water content of the ventilated air was determined under steady-state conditions directly at the tracheal tube or between tracheal tube and HME using a new, high-resolution humidity meter. The results were compared with the absolute water loss of the exhaled air at the gas outlet of the ventilator as an expression of the water loss from the lower airways. Airway resistance was calculated by a standard formula. The daily running costs for both HME and heated humidifier were estimated. RESULTS AND DISCUSSION. Moisture retention was equivalent in both the HME and the heated humidifier (33.7 +/- 1.85 bzw. 34.1 +/- 2.62 mgH2O/l). These data show that modern HMEs are able to maintain physiological air-conditioning even in long-term ventilated patients. The small increase in airway resistance associated with HMEs (3.1 +/- 2.5 mbar/l.s) has to be noted in difficult weaning procedures. Both labour and costs per day are significantly less with HMEs (8.60 vs. 21.70 DM).

Air Conditioning↗
PubMed1996

[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].

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.

Air Conditioning↗
PubMed1996

[The comparative effectiveness of different infusion and blood warming methods].

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)

Blood Physiological Phenomena↗
PubMed1996

[Severe, accidental hypothermia: active rewarming with a simple extracorporeal veno-venous warming-circuit].

We report the case of a 35-year-old male who was admitted to the intensive care unit because of somnolence due to accidental hypothermia. Initial examination showed a Glasgow coma score of 10 and a rectal temperature of 27.4 degrees C. Because of stable circulatory conditions, there was no mandatory indication for rewarming by means of cardiopulmonary bypass. We rewarmed the patient with an extracorporeal veno-venous haemofiltration device combined with a countercurrent fluid warmer. An average increase in body temperature of 1.34 degrees Ch-1 could be obtained. We conclude that the described technique represents an effective and well-controllable method for treatment of hypothermia in patients with stable haemodynamic conditions. Because of the availability of the required equipment, this method can also be practised in hospitals without cardiac surgical departments and cardiopulmonary bypass facilities.

Adult↗
PubMed1996

Influence of different types of recovery positions on perfusion indices of the forearm.

BACKGROUND: Basic life support guidelines of the European Resuscitation Council (ERC) suggest a modified type of recovery position compared to that recommended by the American Heart Association (AHA). However, anecdotal reports and the results of a small study by Fulstow and Smith (Resuscitation 1993; 26: 89-91) gave evidence that the new ERC position may cause an impairment of perfusion of the lower forearm. The aim of our study was to evaluate the effects of different recovery positions on arterial perfusion and venous drainage of the forearm. METHODS: We placed 20 young healthy volunteers randomly in either ERC or AHA position for 15 min first, and in the other position thereafter. Before and between volunteers were positioned supine. In a second series 10 volunteers were positioned according to the same protocol in semiprone positions as described by Morrison, Mirkhur and Craig (MMC), and Rautek's position, respectively. Forearm perfusion indices of the dependent arm were continuously assessed by photoplethysmographic pulsatility change, photoplethysmographic volume change, invasive peripheral venous pressure and non-invasive blood pressure amplitude. Subjective discomfort was assessed non-qualitatively. RESULTS: All indices of arterial perfusion demonstrated an impairment of arterial inflow in ERC, MMC and Rautek's position as well as venous congestion in these three positions. On the contrary, AHA position was associated with no significant changes of arterial flow and only moderate, insignificant signs of venous congestion. CONCLUSION: The results of this study suggest that AHA position causes less circulatory disturbances than the ERC, MMC and Rautek's positions.

Adult↗
PubMed1996

ACD versus standard CPR in a prehospital setting.

BACKGROUND: Animal and human studies in cardiac arrest demonstrate significant improvements in systolic blood pressure, coronary perfusion pressure and total brain and myocardial blood flow with active compression-decompression (ACD) cardiopulmonary resuscitation (CPR). The results of recent studies in patients with out-of-hospital cardiac arrest and use of ACD-CPR are non-uniform and require supplementation. METHODS: In a retrospective non-randomised design, 152 adult patients with prehospital cardiac arrest, not caused by trauma or hypothermia, were studied. Compressions were performed according to the recommendations of the American Heart Association. Three ACD devices were assigned to seven rescue units changing monthly. Study end-points were the rates of return of spontaneous circulation (ROSC), admission to hospital, survival at 24h, hospital discharge and neurologic outcome. RESULTS: 70 (46%) patients underwent standard (STD) CPR and 82 (54%) patients were treated with ACD-CPR. Both groups were comparable with regard to age, sex, witnessed cardiac arrests, bystander CPR, cause of arrest, time intervals, number of defibrillations, and total amount of epinephrine. No significant differences in outcome could be found: 20 patients (29%) who received STD-CPR, and 14 patients (17%) who underwent ACD-CPR survived to hospital discharge. Neither at other end-points nor in any subgroups could any significant differences be discovered. Patients regaining ROSC showed a significant difference in favour of STD-CPR for the end-points of hospital admission, 24-h survival and hospital discharge. CONCLUSION: No significant differences in hospital discharge and neurological outcome were found between STD-CPR and ACD-CPR.

Adult↗
PubMed1995

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.

Adult↗
PubMed1995

[Inadvertant intracardiac entrapment of a Swan-Ganz catheter].

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.

Catheterization, Swan-Ganz↗
PubMed1995

[Heat and moisture exchangers for conditioning of inspired air of intubated patients in intensive care. The humidification properties of passive air exchangers under clinical conditions].

Heat and moisture exchangers (HME) are used as artificial noses for intubated patients to prevent tracheo-bronchial or pulmonary damage resulting from dry and cold inspired gases. HME are mounted directly on the tracheal tube, where they collect a large fraction of the heat and moisture of the expired air, adding this to the subsequent inspired breath. The effective performance depends on the water-retention capacity of the HME: the amount of water added to the inspired gas cannot exceed the stored water uptake of the previous breath. This study evaluates the efficiency of four different HME under laboratory and clinical conditions using a new moisture-measuring device. METHODS. In a first step, the absolute efficiency of four different HME (DAR Hygrobac, Gibeck Humid-Vent 2P, Pall BB 22-15 T, and Pall BB 100) was evaluated using a lung model simulating physiological heat and humidity conditions of the upper airways. The model was ventilated with tidal volumes of 500, 1,000, and 1,500 ml and different flow rates. The water content of the ventilated air was determined between tracheal tube and HME using a new high-resolution humidity meter and compared with the absolute water loss of the exhaled air at the gas outlet of a Siemens Servo C ventilator measured with a dew-point hygrometer. Secondly, the moisturizing efficiency was evaluated under clinical conditions in an intensive care unit with 25 intubated patients. Maintaining the ventilatory conditions for each patient, the HME were randomly changed. The humidity data were determined as described above and compared with the laboratory findings. RESULTS AND DISCUSSION. The water content at the respirator outlet is inversely equivalent to the humidity of the inspired gases and represents the water loss from the respiratory tract if the patient is ventilated with dry gases. Moisture retention and heating capacity decreased with higher volumes and higher flow rates. These data are simple to obtain without affecting the patient and can easily be interpreted. It was demonstrated that, compared to physiological conditions, the DAR Hygrobac and Gibeck Humid Vent 2P-HME coated with hygroscopic salts-were able to maintain sufficient inspiratory humidity and heat. The Pall-HME, solely a condensation humidifier, did not meet the physiological requirements.

Adult↗
PubMed1995

Transpulmonary disposition of prilocaine, mepivacaine, and bupivacaine in humans in the course of epidural anaesthesia.

The pulmonary first-pass kinetics of the amide-linked local anaesthetics prilocaine, mepivacaine and bupivacaine were studied in 33 patients after a single epidural injection. Drug concentrations were monitored before and after lung passage, i.e. in samples withdrawn simultaneously from mixed venous and arterial blood. In most cases, maximum plasma concentrations were observed 10 min after injection (range 2 to 30 min). Two min after injection the local anaesthetics were distinctly extracted by the lung (prilocaine 40%, mepivacaine 20%, and bupivacaine 12%). Prilocaine was retained by the lung more effectively than bupivacaine and mepivacaine. However, a transpulmonary concentration gradient could be observed only for a short time, i.e. maximum 15 min. Altogether, in the case of accidental fast absorption, e.g. inadvertent intravenous injection, arterial peak concentrations of these drugs will be attenuated by passage of the lung. However, the lung will not substantially lower the risk of toxicity by amide-linked local anaesthetics during normal conditions of regional anaesthesia where slow absorption occurs.

Adult↗
PubMed1995

[Efficiency of a mobile oxygen concentrator for mechanical ventilation in anesthesia. Studies with a metabolic lung model and early clinical results].

Oxygen (O2) for clinical application is generally provided from either a central gas supply via a hospital pipeline system or is delivered to the working place in cylinders as compressed gas. An alternative source is the one-site generation of O2 from air using O2 concentrators based on molecular sieve technology. Whereas O2 concentrators for anaesthesia in remote areas or underdeveloped countries are wide-spread, in Germany their use is common in neither hospitals nor anaesthesiological practice. The maximum O2 content produced by concentrators is 96% with about 4% argon (Ar) and minimal amounts of nitrogen and other noble gases. The total O2 production is systematically limited, and therefore, the delivered concentration decreases with higher flows. There is also a potential possibility of Ar accumulation in rebreathing anaesthesia systems with reduced fresh gas flow. We investigated the efficiency and potential disadvantages of using O2 concentrators in anaesthesia and the influence of Ar on the accuracy of anaesthetic gas monitors. METHODS. The efficiency of the concentrator was characterised as O2 concentration depending on delivered gas flow. The degree of Ar accumulation in rebreathing anaesthesia systems was obtained with an O2-consuming and CO2-producing metabolic lung model consisting of a water-cooled burning chamber with an adjustable gas jet. The expiratory CO2 content was set to approximately 7%, representing an O2 consumption of 350 ml/min while ventilating the model with 500 ml tidal volume and 10 breaths/min. The inspiratory O2 concentration was adjusted to 35% or 70%; the fresh gas flow was set to 0.5 or 1 l/min. The accuracy of different types of anaesthesia monitors for O2, CO2, volatile anaesthetics, and nitrous oxide in the presence of Ar was checked in comparison with data obtained with a mass spectrometer. To evaluate the usefulness of O2 concentrators for anaesthetic practice, the function of a respirator-concentrator unit was investigated in clinical routine for 8 weeks. RESULTS. The efficiency of the concentrator is flow-rate dependent: O2 concentrations higher than 90% are only achieved with flow rates below 5 l/min and decrease to values lower than 50% at 12 l/min or more. Ar accumulation occurred in rebreathing circuits but exceeded values higher than 10% only under minimal-flow conditions (fresh gas flow 0.5 l/min). Ar did not influence the accuracy of common anaesthetic gas monitors. In clinical practice, the performance of anaesthesia using O2 from an O2 concentrator generated no additional problems. CONCLUSIONS. For the future, the use of O2 concentrators for anaesthesia seems to be a practicable alternative to compressed O2 from cylinders. The main application could be in small operating units or anaesthesia practices. The method is safe and without additional risk of hypoxia, even in rebreathing systems and closed circuits, when the O2 concentration in the inspired gas is measured.

Anesthesia↗
PubMed1993

[Prevention of pneumonia by endotracheal micronebulization of tobramycin].

In 69 artificially ventilated patients the clinical, bacteriological and pharmacological effects of endotracheally administered tobramycin were studied in comparison to a control group. In the therapy group, 52% of all specimens were sterile, in the control group only 25%. During the first 4 days these changes were significant (p < 0.05). In the therapy group the endotracheal colonisation with ps. aeruginosa was significantly lower between the 4th and 14th day (p < 0.05). The incidence of secondary pneumonia was reduced from 42% to 17.5% (not significant). Systemic administration of antibiotics, e.g. of aminoglycosides, was significantly more often necessary in the control group. No increasing of growth of fungi in the upper respiratory tract was observed, but these was a non-significantly higher incidence mainly of staph. epidermidis. The application of 80 mg tobramycin four times a day as an aerosol was well tolerated by the patients. Under there conditions, tobramycin could not be measured in the serum. No allergic reactions, increased respiratory pressures or bronchoconstrictions were observed.

Adolescent↗
PubMed1993

[Anesthesia equipment and respirators. Fundamentals].

The decrease of functional residual capacity during anaesthesia makes mechanical ventilation mandatory. Volume- and pressure-controlled modes should both be possible. Ventilator-assisted spontaneous respiration is rarely indicated during general anaesthesia, and this mode is therefore unnecessary for anaesthesia machines. From ecological and economical points of view, modern anaesthesia machines should be equipped with a circle system enabling administration of anaesthesia under rebreathing conditions with reduced fresh gas flow. Basic requirements are low gas leakage of the system, precise gas-flow dosage, especially at low flow rates, and integrated monitoring of in- and expiratory gases. In principle, older machines may also comply with these requirements if they are appropriately upgraded and properly maintained. There is reasonable doubt whether a further reduction of flow to less than 1 l/min fresh gas is of any benefit. To maintain patient safety without compromising practicability, a tremendous surplus of technical efforts is necessary. For easier management, fresh-gas-flow-compensated circle systems facilitating adjustment of tidal volume after changes of fresh gas flow are desirable. Precautions aimed at the prevention of ventilation with hypoxic gas mixtures are still insufficient: the oxygen failure devices (nitrous oxide flow shutoff valve) are only effective if oxygen pressure from the gas supply is low. Distinct improvements have been achieved with oxygen ratio systems, preventing the administration of hypoxic gas mixtures at fresh gas flows higher than 1 l/min.

Anesthesiology↗
PubMed1992

[Is the lithium chloride-coated heat and moisture exchanger a danger for patients?].

Such hygroscopic compounds as LiCl, CaCl2, and MgCl2 are used to improve water retention capacity and, as a consequence, the effectiveness of heat and moisture exchangers (HME). Resorption of these substances via the bronchopulmonary tract and a resulting systemic action cannot be excluded, especially if additional active moisturizing devices are used. The narrow therapeutic range of lithium is known, as are its unwanted side effects, such as nausea, vomiting, somnolence and even cardiac arrhythmia. These are symptoms that also frequently occur during anaesthesia and intensive care, so that differentiation against effects of lithium is nearly impossible. We investigated whether, in theory and in practice, LiCl-coated HME could result in effective Li plasma concentrations. We measured (1) total LiCl content of HMEs, (2) release of this content, simulating the worst-case situation with a breathing model, and (3) lithium plasma concentrations of adult patients being ventilated during anaesthesia with a rebreathing circuit and LiCl-coated HME, but with no additional active moisturizing system incorporated. RESULTS. The results show striking differences with LiCl content ranging from 3 to 251 mg varying not only between different types of HME but also within the same lots. After 20 min of ventilation more than 90% of the LiCl coating was rinsed into the test lung of the breathing model. In practical use, we observed an increase in lithium plasma concentration in 3 of 20 investigated patients. The plasma values of maximum 49.5 micrograms/l (= 0.007 mmol/l) do not amount to potentially toxic concentrations. Nevertheless, clinically relevant concentrations might occur in patients with small distribution volumes, e.g. newborns or infants with frequent exposition within short intervals such as in intensive care units. The differences in lithium content also indicate qualitative differences in water retention capacity. Because of the potential side effects of lithium, we prefer qualitatively equivalent HMEs, e.g., with MgCl2 or CaCl2 as hygroscopic substance.

Adult↗
PubMed1992

[Vigilance disorders in intensive care patients. The central anticholinergic syndrome as a differential diagnosis of a brain stem lesion].

Four days after implantation of a biventricular assist device (Berlin heart) the 39-year-old patient showed a sudden loss of vigilance and tetraplegia. Clinical skills and neurophysiological states indicated a serious lesion of the brain stem. After a test application of Physostigmine 2 days later, the neurological deficits improved dramatically. The case demonstrates that neurological deficits can also be caused by or combined with an acute anticholinergic syndrome. The application of Physostigmine allows disorders caused by brain lesions to be differentiated from transitory syndromes.

Adult↗
PubMed1991

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.

Abdomen↗