[Ulcerating Herpes simplex infections in intensive care patients]

Herpes simplex infections are potentially a life-threatening situation for immunocompromised as well as critically ill patients. The correct diagnosis is made more difficult in comatose patients by the fact that the characteristic symptom of extreme pain cannot be registered. The clinical dermatological findings (polycyclic configuration, easily bleeding ulcers) are thus especially important in patients under intensive care conditions. As examples, the cases of 3 critically ill patients (subarachnoid bleeding or head injury) developing therapy-resistant, flat sacral or perioral skin ulcers with peripheral blisters are presented. Herpes simplex virus was confirmed immunohistologically and in the smear test. All patients subsequently died. These cases emphasize that patients in the intensive care unit are in danger of developing a chronic persistent Herpes simplex infection due to latent immunosuppression. Chronic persistent Herpes infections may be underrated in intensive therapy, and must always be ruled out in case of therapy-resistant erosions or ulcerations.

[Latex allergy. Perioperative management in anesthesia and cardiac anesthesia]

The frequency of perioperative allergic responses to latex has markedly increased over the last 10 years. High risk groups to develop sensitivity to latex include healthcare workers, workers in the latex industry, children suffering from congenital malformations such as spina bifida or urogenital deformities and patients who have undergone multiple surgical procedures. During surgery, patients have contact to a variety of products containing latex. To prevent anaphylactic reactions, all hospitals have to develop strategies to identify and manage patients sensitised to latex or belonging to high risk groups. The aim of this paper is to describe safe perioperative management in a latex-free environment.

[Cerebral oxygen reactivity determination--a simple test with potential prognostic relevance]

Brain tissue oximetry (ptiO2) using flexible micro-polarographic electrodes is a loco-regional approach to monitor oxygen supply to the injured brain, after neuronal damage. In patients after severe head injury (SHI), disturbances of CBF and CO2 related vasoconstriction have been demonstrated. CO2 reactivity testing may assist to determine outcome in these patients. Not much information is available on the preservation of vasoreactivity to arterial hyperoxia after neuronal damage. Therefore, we studied the response of ptiO2 in 7 piglets and in 14 patients on day one after trauma to 100% FiO2 ventilation (O2rea) and analyzed the 3 month outcome using the Glasgow-Outcome-Score (GOS). In the animal study, we placed a Paratrend 7 (P7) sensor for ptiO2 measurements in the non injured frontal white matter. The animals were anesthetized and mechanically ventilated. FiO2 was increased from 30 (+/- 5)% to 100% over a period of 5 minutes. In patients, we placed the P7 probe in the frontal lobe. FiO2 was increased from 35 (+/- 5)% to 100% over a period of 6 hours. O2rea was tested by calculating the percentage change of ptiO2 during 100% FiO2 ventilation, compared to the baseline value of 35% FiO2. By analyzing the patient outcome, we were able to define two patient populations according to the GOS at three month (Group I: favorable outcome [GOS 0-2]; Group II: poor outcome [GOS 3-4]). For the non-injured brain tissue in animals were revealed an O2rea = 0.21 (+/- 0.12).

PATIENTS

Group I: O2rea = 0.4 (+/- 0.16); Group II: 0.9 (+/- 0.6). Group I and II were statistical significant different (p < 0.05; unpaired t-test). Oxygen reactivity in severely head patients is a simple test with prognostic value using ptiO2 measurement. These results may be explained by the close relationship of CBF disturbances to oxygen vasoreactivity after traumatic brain injury. The O2rea in animals without neuronal damage is smaller than in patients after SHI. We speculate, the animal data could be considered as normal value of O2rea in non injured brain tissue.

Electromyographic evidence of reduced muscle activity when ULF-TENS is applied to the Vth and VIIth cranial nerves

The object of this study was to determine if the resting muscle activity of TMD patients with measured hyperactivity (EMGave > 2.0 microvolts) could be reduced by the application of ULF-TENS (Ultra-Low-Frequency-Transcutaneous Electrical Neural Stimulation) [(BioTENS) BioResearch, Inc. Milwaukee, WI]. Twenty-nine patients with resting muscle hyperactivity and ten without resting muscle hyperactivity were selected from a series of 124 consecutively diagnosed TMD patients. Electromyographic records were taken bilaterally (with the mandible at rest) from the superficial masseter, anterior temporalis, anterior digastric, and posterior temporalis muscles before and after the application of ULF-TENS. The EMG data were averaged. For the 85 muscles that were found initially to exceed the usual cutoff of 2.0 microvolts, means and standard deviations were calculated. The "before TENS" levels were: mean = 3.353 +/- 1.44227 and the "after TENS" values were: mean = 1.844 +/- 0.92421. Using a student t-test, we found the difference between the before and after levels significant (p < .0005). Additionally, means and standard deviations were calculated for each muscle (Ta, Mm, etc.) separately and also found to be significantly different (before Vs after TENS). In these "hyperactive" patients, the nonhyperactive muscles were also pooled, the means calculated before (mean = 1.21 +/- 0.456) and after (mean = 1.00 +/- 0.345) TENS and found to be significantly different (p < 0.01). For the ten patients exhibiting no muscle exceeding the 2.0 microvolt cutoff (mean = 1.08 +/- 0.415), no significant change (in levels) was observed after ULF-TENS (mean = 0.96 +/- 0.359; p > 0.88); however, when we calculated the "paired difference," we found a significant reduction, albeit very slight, in these patients' muscles, too. We conclude that ULF-TENS has an activity-reducing effect on the resting EMG levels of both hyperactive and relaxed muscles. It also appears that while the > 2.0 microvolt cutoff is useful for identifying patients that are hyperactive at rest, it does not identify complete relaxation of masticatory muscles.

Experiences with continuous intra-arterial blood gas monitoring

Management of critically ill patients requires frequent arterial blood gas analyses for assessing the pulmonary situation and adjusting ventilator settings and circulatory therapeutic measures. Continuous arterial blood gas analysis is a real-time monitoring tool, which reliably detects the onset of adverse pulmonary effects. It gives rapid confirmation of ventilator setting changes and resuscitation and helps to ensure precise adjustment of therapy. In this study a newly available fiber optic sensor system has been employed for continuous intraarterial blood gas monitoring. The measurement performance was compared with a bench top blood gas analyzer. A prospective study was performed enrolling 20 patients undergoing surgery. A comparison between intermittent blood gas analyses (ABL Radiometer 610) and the results of continuous blood gas monitoring (Paratrend 7+, Agilent Technol.) was performed by simultaneous measurements. Statistical analysis in agreement with the method of "Bland and Altman" was employed. Two case reports are provided of patients with Acute Adult Respiratory Distress Syndrome and rapid changes in ventilator settings. Over a range of arterial oxygenation from 10 to 50 kPa the bias for pO2-measurement was 0.2 (limits of agreement 4), R2 = 0.9. If the arterial pO2 was higher than 50 kPa the bias was -7 (10) kPa. PCO2-measurement showed a bias of 0.25 (limits of agreement 0.45), R2 = 0.7. pH bias was -0.02 (limits of agreement 0.04), R2 = 0.7. The Paratrend 7+ sensor proved to be clinical feasible and showed an improved precision in terms of clinical situations with an arterial pO2 smaller than 50 kPa. However, the results are not much different regarding the findings with older systems consisting of hybrid technology combining optodes and electrochemical oxygen measurement. The advantages might be seen if the sensor is used for a period over several days in patients on ICU as demonstrated by the two case reports.

In-vivo studies do not support a major functional role for the Gly389Arg beta 1-adrenoceptor polymorphism in humans

beta 1-adrenoceptors play a pivotal role in regulating contractility and heart rate in the human heart. Recently, a polymorphism of the beta 1-adrenoceptor has been detected: at amino acid position 389 either Gly or Arg has been found with the Gly389 exhibiting reduced responsiveness upon agonist-induced stimulation in vitro. In order to find out whether the Gly389 polymorphism exhibits blunted responsiveness also in vivo we studied, in healthy volunteers, the effects of exercise on heart rate and heart rate-corrected duration of electromechanical systole (QS2c as a measure of inotropism) which, in humans, is mediated by beta 1-adrenoceptors stimulation. Twenty-four healthy volunteers (12 female, 12 male) homozygous for the Gly389 or Arg389 exercised on a bicycle in supine position (25, 50, 75 and 100 W for 5 min each), and heart rate and QS2c were assessed; in addition, plasma renin activity (PRA) was determined which is also regulated by beta 1-adrenoceptors in humans. Exercise caused work-load dependent increases in heart rate and PRA, and shortening of QS2c; however, these changes were not significantly different between the Gly389 and Arg389 polymorphism. Thus, these three beta 1-adrenoceptor responses did not differ between volunteers with the Arg389 versus the Gly389 polymorphism. Intragroup analysis, however, revealed that exercise induced increase in heart rate and shortening of QS2c were higher in female than in male volunteers. In conclusion, our data do not support the idea that the reduced responsiveness of Gly389 against agonist-induced stimulation observed in vitro is of major functional importance in vivo.

Wavelet transforms of TM joint vibrations: a feature extraction tool for detecting reducing displaced disks

The objective of this study was to determine if wavelet transforms (WTs) of vibrations recorded from temporomandibular joints (TMJs) with reducing displaced disks could be visually separated from WTs of vibrations recorded from normal TM joints by blinded observers. From a continuous series of 124 diagnosed TMD patients, 28 were confirmed with at least one reducing displaced disk. Vibrations were recorded from each affected joint, together with incisal point movements, using BioPAK (BioResearch, Inc., Milwaukee, WI) during opening, closing, and lateral excursions. Identical recordings were taken from 28 patients who were determined to have normal "nondisplacing, nondisplaced" joints. A 3x7 Biorthogonal Spline Wavelet Transform was used to create three-dimensional time-frequency graphs of the vibration events for each subject. Printed copies of the graphs were then shown sequentially to seven blinded observers who were asked to separate them into two groups without any knowledge of their significance. Each observer was independently able to separate the two groups without committing more than one error. We conclude that the vibrations generated by reducing displaced disks are sufficiently different from the vibrations of normal joints to be separable by visual inspection of their respective wavelet transforms.

[Continuous recording of cardiac output volume with the OptiQ system--experiences with clinical application]

This report discusses initial experiences with the clinical application of continuous cardiac output measurement (OptiQ SvO2/CCO-System). The system was used in 9 intensive care patients suffering either global cardiac insufficiency or systemic inflammatory response syndrome. Continuous cardiac output measurement was recorded during a period of stable blood pressure conditions and compared with the results of the conventional thermodilution method (bolus technique) in these patients. Regression analyses yielded r = 0.523 (r2 = 0.274) for the "urgent" mode, r = 0.943 (r2 = 0.889) for the "fast" mode, r = 0.953 (r2 = 0.907) for the "fast filter" mode and r = 0.990 (r2 = 0.980) for the "normal" mode. Mean differences between the continuous and the bolus technique were calculated as -0.13 +/- 1.81 l/min for the "urgent" mode, -0.42 +/- 0.51 l/min for the "fast" mode, -0.14 +/- 0.48 l/min for the "fast filter" mode and -0.08 +/- 0.19 l/min for the "normal" mode. After a period of two days, the costs of the conventional bolus technique significantly exceeded those of continuous measurement. The expenses for the conventional thermodilution technique are largely determined by the frequency of application and, hence, by the personnel and laboratory costs. In our experience, easy component handling and stable measuring properties make this new method of continuous cardiac output monitoring a valuable method in the diagnose and care of patients who are critically ill.

Blunted cardiac responses to receptor activation in subjects with Thr164Ile beta(2)-adrenoceptors

BACKGROUND

Recent evidence indicates that certain genotypes of beta(2)-adrenoceptors (AR) may indicate an increased risk of cardiovascular disease or an increased rate of disease progression. Of particular importance, the Thr164Ile polymorphism, which is found in approximately 4% of humans, shows decreased receptor signaling, blunted cardiac response when expressed in transgenic mice, and is associated with a decreased survival rate in patients with congestive heart failure.

METHODS AND RESULTS

In this study, we compared functional activity, ie, chronotropic (heart rate increases) and inotropic (duration of the electromechanical systole) responses to intravenously administered terbutaline, in 6 subjects (4 women and 2 men) who were heterozygous for Thr164Ile with the responses in 12 volunteers (6 women and 6 men) who were homozygous for wild-type (WT) beta(2)-AR (ie, Arg16, Gln27, and Thr164). The beta(2)AR polymorphism significantly affected the dose-response curves for terbutaline-induced inotropic and chronotropic responses: compared with WT individuals, subjects with the Thr164Ile receptor had substantial blunting in maximal increases in heart rate (WT, 29.7+/-3.9 beats/min; Ile164, 20.7+/-1.9 beats/min; P:=0.016) and a shortening of the duration of electromechanical systole (WT, 51.9+/-4.5 ms; Ile164, 37.9+/-4.6 ms; P:=0.02).

CONCLUSIONS

These data show that humans with the Ile164 genotype show blunted cardiac beta(2)-AR responsiveness, which may help explain the decreased survival of patients with this genotype in the setting of congestive heart failure.

Human cardiac beta1- or beta2-adrenergic receptor stimulation and the negative chronotropic effect of low-dose pirenzepine

OBJECTIVES

The M1-muscarinic receptor antagonist pirenzepine in low doses (<1 mg intravenously) decreases heart rate. We investigated whether these effects of pirenzepine differ in volunteers with activated cardiac beta1-adrenergic receptors versus activated cardiac beta2-adrenergic receptors.

METHODS

In 17 male volunteers (25 +/- 1 years) we studied effects of pirenzepine infusion (0.5 mg intravenous bolus followed by continuous infusion of 0.15 microg/kg/min) on heart rate and heart rate-corrected duration of electromechanical systole (QS2c, as a measure of inotropism) that had been stimulated by activation of cardiac beta1-adrenergic receptors (bicycle exercise in the supine position for 60 minutes at 25 W) or cardiac beta2-adrenergic receptors (continuous intravenous infusion of 100 ng/kg/min terbutaline).

RESULTS

Bicycle exercise and terbutaline infusion significantly increased heart rate and shortened QS2c. When pirenzepine was infused 20 minutes after the beginning of the exercise or terbutaline infusion, heart rate decreased in both settings by approximately the same extent (approximately -10 to -14 beats/min), although exercise and terbutaline infusion continued; however, QS2c was not affected. Pirenzepine (0.05 to 1 mg intravenous bolus)-induced decrease in heart rate was abolished after 6 days of transdermal scopolamine treatment of volunteers.

CONCLUSIONS

Low-dose pirenzepine decreased heart rate by muscarinic receptor stimulation, because this was blocked by scopolamine. Moreover, low-dose pirenzepine did not differentiate between cardiac beta1- or beta2-adrenergic receptor stimulation; however, low-dose pirenzepine did not affect cardiac contractility as measured by QS2c. Low-dose pirenzepine therefore exerted a unique pattern of action in the human heart: it decreased heart rate (basal and beta1- and/or beta2-adrenergic receptor-stimulated) without affecting contractility.

Cerebrovenous blood temperature-influence of cerebral perfusion pressure changes and hyperventilation: evaluation in a porcine study and in man

The objective of the first part of this study was to use an animal model to investigate the relationship between temperature in the cerebrovenous compartment and cerebral perfusion pressure. In the second part of the study, the objective was to examine the influence of hyperventilation and hypothermia on jugular bulb temperature and body temperature in patients undergoing elective neurosurgery. Intracranial pressure was increased artificially by inflating an infratentorial supracerebellar placed balloon catheter in nine pigs under general anesthesia. Temperature was monitored by thermocouples inserted in the sagittal sinus, white matter of the left lobe and abdominal aorta during the ensuing decrease in cerebral profusion pressure (CPP). Cerebrovenous blood temperature (jugular bulb) and body temperature (urinary bladder) were simultaneously monitored in 24 patients undergoing craniotomy. Moderate hyperventilation was performed in all patients. Cerebrovenous blood and core body temperature were recorded and differences between these two temperatures calculated at the beginning and the end of hyperventilation. At the beginning of the intracranial pressure (ICP), increase mean temperatures of cerebrovenous blood and cerebral tissue (left lobe) were lower than core body temperature. During CPP reduction the difference between core body temperature and cerebrovenous blood temperature increased significantly from 0.86+/-0.44 degrees C prior to ICP rise to 1.19+/-0.58 degrees C at maximum ICP. Before hyperventilation, cerebrovenous blood temperature was higher in 19 patients (+/- difference: 0.34 degrees C +/- 0.27) and equal or lower in five patients (difference: -0.08 degrees C +/- 0.11), than core body temperature. At the end of hyperventilation, the difference between cerebrovenous blood temperature and core body temperature increased (+0.42 degrees C +/- 0.24) in those 19 patients who had started with a higher cerebrovenous blood temperature and decreased (-0.10 degrees C +/- 0. 18) in the other five patients. Both studies demonstrated that the temperature of cerebrovenous blood is influenced by maneuvers which are supposed to decrease cerebral blood flow.

Pseudomonas aeruginosa exoenzyme S is a biglutamic acid ADP-ribosyltransferase

Kinetic analysis of two mutations within Pseudomonas aeruginosa exoenzyme S (ExoS) showed that a E379D mutation inhibited expression of ADP-ribosyltransferase activity but had little effect on the expression of NAD glycohydrolase activity while a E381D mutation inhibited expression of both activities. These data identify ExoS as a biglutamic acid ADP-ribosyltransferase, where E381 is the catalytic residue and E379 contributes to the transfer of ADP-ribose to the target protein.

Cardiac effects of beta-adrenoceptor antagonists with intrinsic sympathomimetic activity in humans: beta1- and/or beta2-adrenoceptor mediated?

The aim of this study was to find out whether cardiac responses to the beta-adrenoceptor antagonists with intrinsic sympathomimetic activity (ISA) xamoterol and celiprolol are mediated by cardiac beta1- or beta2-adrenoceptors or both. For this purpose we assessed, in six healthy male volunteers, the effects of xamoterol (100 and 200 mg, p.o.) and celiprolol (200, 600, and 1,200 mg, p.o.) on blood pressure, heart rate, and heart rate-corrected duration of the electromechanical systole (QS2c, as a measure of inotropism). Xamoterol, in both doses, increased systolic blood pressure and heart rate, transiently decreased diastolic blood pressure, and shortened QS2c; all these effects were attenuated after pretreatment of the volunteers with the beta1-adrenoceptor antagonist bisoprolol. Celiprolol, in all three doses, increased heart rate, decreased diastolic blood pressure, and shortened QS2c but only marginally increased systolic blood pressure. Bisoprolol did not attenuate these celiprolol effects but rather enhanced celiprolol effects on systolic blood pressure and heart rate. In a further set of experiments, we studied cardiovascular effects of celiprolol in six healthy volunteers whose beta2-adrenoceptors had been desensitized by a 2-week treatment with 3x5 mg/day terbutaline. Under these conditions, celiprolol failed to increase heart rate or to shorten QS2c. We conclude that, under resting conditions, in healthy volunteers, beta-adrenoceptor antagonists with ISA can exert increases in heart rate and contractility that are mediated by either cardiac beta1-adrenoceptor (xamoterol) or cardiac beta2-adrenoceptor (celiprolol) stimulation. Thus in the human heart, the ISA of beta-adrenoceptor antagonists can be a beta1- or beta2-adrenoceptor agonistic component.

Simultaneous continuous measurement of pO2, pCO2, pH and temperature in brain tissue and sagittal sinus in a porcine model

INTRODUCTION

The clinical use of brain tissue oxygen measurement in patients with severe head injury is increasing. It is important to compare the findings in brain tissue with cerebrovenous blood oximetry, to obtain normal values and to find out limitations of the method. We evaluated a newly available multisensor probe simultaneously in the brain tissue and in the sagittal sinus in a porcine animal model.

METHODS

We placed the Paratrend 7-probe (BSL, High Wycombe, UK) in the left frontoparietal white matter and measured pO2 (PtiO2), pCO2 (ptiCO2), pH and temperature while simultaneously measuring these parameters (pcvO2, pcvCO2) in the sagittal sinus in 7 pigs under general anaesthesia during oxygen enhancement.

RESULTS

The relation between oxygen increase in brain tissue and in the sagittal sinus showed a coefficient of correlation (CCmean) rmean = 0.96. The quantitative response in brain tissue was much more sensitive than in the sinus. A close correlation between pCO2 in brain tissue and sagittal sinus and the increase of the inspired oxygen was seen: CC ptiCO2 to arterial oxygen pressure (paO2) - rmean = 0.67, CC pcvCO2 to paO2 - rmean = 0.88.

CONCLUSIONS

Measuring partial oxygen pressure in brain tissue is more responsive to physiological variations, and the absolute values are more sensitive than oxygen measurement in the cerebrovenous compartment. This is important for interpreting measured values and introducing new coefficients for patient monitoring.

Terbutaline-induced desensitization of human cardiac beta 2-adrenoceptor-mediated positive inotropic effects: attenuation by ketotifen

BACKGROUND

In patients with chronic heart failure cardiac beta 1-adrenoceptors are desensitized whereas beta 2-adrenoceptors are only marginally affected. The mechanism underlying this differential regulation is not known.

OBJECTIVES

To find out whether or not human cardiac beta 2-adrenoceptors might be 'resistant' to agonist-induced desensitization and whether or not the antiallergic drug ketotifen might attenuate possible desensitization.

METHODS

We investigated, in a single blinded, randomised, placebo-controlled, cross-over study of ten healthy male volunteers (mean age, 25.3 +/- 0.7 years), the effects of two weeks treatment with the beta 2-adrenoceptor agonist terbutaline (3x5 mg/day p.o.) with and without simultaneous treatment with ketotifen (2x1 mg/day p.o. for three weeks) or placebo on beta-adrenoceptor-mediated cardiovascular effects. Cardiovascular effects were assessed as isoprenaline (3.5-35 ng/kg/min)- and terbutaline (25-150 ng/kg/min)-infusion-induced increases in heart rate and systolic blood pressure, decreases in diastolic blood pressure and shortening of the systolic time intervals (STIs), heart rate corrected duration of electromechanical systole (QS2c) and pre-ejection period (PEP; as a measure of inotropism).

RESULTS

Ketotifen did not significantly affect basal haemodynamics in the volunteers. Isoprenaline- and terbutaline-infusion caused dose-dependent increases in systolic blood pressure and heart rate, decreases in diastolic blood pressure and shortening of QS2c and PEP, whereby isoprenaline effects were more pronounced. After two weeks of treatment with terbutaline p.o., isoprenaline- and terbutaline-infusion-induced increases in heart rate, shortening of QS2c and PEP were significantly reduced whereby terbutaline-infusion effects were markedly more attenuated than isoprenaline-infusion effects. Ketotifen significantly reduced terbutaline p.o. treatment-induced attenuation of all terbutaline-infusion effects (largely beta 2-adrenoceptor-mediated) and the isoprenaline-infusion-induced increase in heart rate (beta 1- and beta 2-adrenoceptor-mediated), but did not (or only marginally) affect reduction in isoprenaline-induced shortening of QS2c and PEP (largely beta 1-adrenoceptor-mediated).

CONCLUSION

Human cardiac beta 2-adrenoceptors are not 'resistant' to agonist-induced desensitization: Ketotifen might prevent such beta 2-adrenoceptor-agonist-evoked desensitization.

[Cisatracurium in patients with compromised kidney function. Pharmacodynamic and intubation conditions under isoflurane-nitrous oxide anesthesia]

OBJECTIVES

The choice of cisatracurium, especially for patients with organ dysfunction, seems to be beneficial, because of organ-independent Hofmann-elimination and less histamine release propensity. This study was designed to investigate pharmacodynamics and intubating conditions after bolus administration of 0.15 mg/kg cisatracurium (3 x ED95) in patients with renal failure and maintained with isoflurane/N2O in oxygen.

METHODS

20 patients with renal failure and 19 patients with normal renal function were studied. Anaesthesia was induced with fentanyl (2-3 micrograms/kg) and thiophentone (4-7 mg/kg). After rapid bolus administration of 0.15 mg/kg cisatracurium (3 x ED95), onset time and intubating conditions were assessed. Clinical duration (DUR 25%), recovery index and duration 90% were investigated by acceleromyography. Changes of mean arterial blood pressure and/or heart rate > or = 20% were defined as clinically significant.

RESULTS

The onset time (3.1 +/- 0.8 min) was shorter in patients without renal failure (Cis-1) than in patients with normal renal function (3.6 +/- 0.8 min), but without statistical significance. Intubating conditions, scored according to a 3-step scale, were slightly better in patients with normal renal function. Other pharmacodynamic parameters did not differ significantly. However, a small tendency to a prolonged recovery with a wide inter-individual variety was characteristic for patients with renal failure. Regarding the hemodynamic actions, only minor individual cardiovascular changes occured. No clinical evidence of histamine release was observed in any patient.

CONCLUSIONS

The result of this clinical study suggest, that cisatracurium is a suitable choice for patients with renal failure. The necessity for an intraoperative neuromuscular monitoring is given by the marked heterogeneity in the recovery parameters in patients with renal failure.

Temperature of the cerebrovenous blood in a model of increased intracranial pressure

Hypothermia has a considerable protective effect during brain ischemia. On the other hand small increases of brain temperature have a remarkable effect on the exacerbation of neurological damage following an ischemic event. Hyperthermia of the brain tissue after severe head injury is described. The effect of acutely increased intracranial pressure on cerebrovenous blood temperature is not described yet. The aim of this study was to investigate the relationship between temperature in the cerebrovenous compartment (Tcv) and changes of the CPP in an animal model of raised intracranial pressure.

METHODS

A thermocouple was inserted in the sagittal sinus in 9 pigs under general anesthesia. By stepwise inflating a supracerebral and infratentorial placed balloon catheter intracranial pressure (ICP) was increased and CPP concomitantly decreased. The central body temperature was measured simultaneously in the abdominal aorta (Ta) with a second thermocouple.

RESULTS

In our model th Tcv was lower than Ta at the beginning of the ICP increase. The mean difference between Ta and Tcv, (delta Ta-cv) was 0.86 degree C (+/- 0.44) prior to ICP increase and 1.19 degrees C (0.58) at the maximum ICP increase. Thus, delta Tav increased during CPP reduction. This relation was represented by an adjusted R(square) of r2 = 0.89 (p < 0.001).

CONCLUSIONS

The CPP decrease, caused by an increasing ICP, results in changes of the cerebrovenous blood temperature. Interpreting the present results the experimental situation of a relative colder cerebral compartment in comparison to the central body temperature has to be considered. However, the results imply, that simultaneous temperature monitoring of the central body temperature and the cerebrovenous blood temperature is an additional source of information about relative changes of the CBF.

Validating of a transoesophageal ultrasonic-Doppler-probe to the detection of air in the venous blood

OBJECTIVES

The aim of this study was to compare the sensitivity of a newly applied transoesophageal ultrasonic Doppler sensor for detection of air with the traditional precordial ultrasonic Doppler sensor in clinical use.

METHODS

We studied 16 patients undergoing neurosurgical procedures in a sitting position. Two ultrasonic Doppler devices were compared as to their ability to detect venous air embolisms (VAE): transoesophageal (ODM II, co. Abbott) versus a precordial ultrasonic Doppler sensor (Parks Medical Electronics Inc.). After establishing general anaesthesia and endotracheal intubation, we applied an ultrasonic Doppler sensor to the right sternal border of the patient's chest and inserted an ultrasonic Doppler probe into the oesophagus. With the patient in the sitting position, microparticularly d-galactose was injected to verify the efficacy of both ultrasonic Doppler devices.

RESULTS

Using ODM II by positioning the probe toward the azygos vein, a dosage of 1 ml microparticularly d-galactose was detected in every patient. When adjusting the ODM II-probe on the right myocardial wall or using the precordial ultrasonic Doppler sensor, the administration of microparticularly d-galactose was detected by the devices in only 11 patients.

CONCLUSIONS

This study demonstrates that a transoesophageal ultrasonic Doppler sensor (ODM II) is more efficient than the precordial ultrasonic Doppler sensor for monitoring patients who are at risk of VAE by sonification of the azygos vein.

Glycosphingolipids as novel targets for T-cell suppression by the B subunit of recombinant heat-labile enterotoxin

Heat-labile enterotoxin subunit B (LTB) is a noncatalytic protein derived from Escherichia coli that binds to ganglioside GM1, a glycosphingolipid on the surface of mammalian cells. In this study, the effects of recombinant LTB (rLTB) on murine lymphocytes were examined in vitro. T and B cells readily bound fluorescein isothiocyanate-labeled rLTB. CD8+ T cells bound twice as much as CD4+ T cells and B cells. Exposure of T-cell subsets and B cells to rLTB abrogated mitogen-driven proliferation. CD8+ T cells were more susceptible to rLTB than either CD4+ T cells or B cells. There were differences in the sensitivity of lymphocytes from various strains of mice to rLTB. This was attributed to qualitative and quantitative differences in the CD4+ T cells. rLTB induced apoptosis in both T-cell subsets, but the level was significantly higher in CD8+ T cells. Apoptosis peaked at around 8 h after exposure to rLTB and incubation at 37 degrees C. Binding to ganglioside GM1 was essential for suppression, since rLTB/G33D, a mutant which does not bind GM1, failed to inhibit proliferation or induce apoptosis. Naive T cells, which were acutely sensitive to rLTB, became more resistant after activation. Conversely, activated T cells regained their sensitivity to rLTB when they reverted back to a resting state. A 1-h pulse with rLTB was sufficient to inhibit T-cell proliferation and cytotoxic-T-lymphocyte generation in primary mixed lymphocyte reaction cultures. CD8+ T cells were preferentially depleted in these cultures. rLTB also induced functional modifications in T cells as indicated by inhibition of gamma interferon secretion after polyclonal activation. Thus, rLTB may have immunomodulatory properties independent of its ability to induce apoptosis.

Comparison between continuous brain tissue pO2, pCO2, pH, and temperature and simultaneous cerebrovenous measurement using a multisensor probe in a porcine intracranial pressure model

Local brain tissue oxygenation (p(ti)O2) and global cerebrovenous hemoglobin saturation (SjO2) are increasingly used to continuously monitor patients after severe head injury (SHI). In patients, simultaneous local and global oxygen measurements of these types have shown different results regarding the comparability of the findings during changes in CPP and ICP. This is in contrast to theoretical expectations. The aim of this study was to compare p(ti)O2 measurement with cerebrovenous oxygen partial pressure measurement (p(cv)O2) in an animal intracranial pressure model. To this end, a multisensor probe was placed in the left frontoparietal white matter to measure p(ti)O2, pCO2 (p(ti)CO2), pH (pH[ti]), and temperature (t[ti]) while simultaneously measuring these same parameters (p(cv)O2, p(cv)CO2 pH(cv), t[cv]) in the sagittal sinus of 9 pigs under general anesthesia. By stepwise inflating a balloon catheter, placed in supracerebellar infratentorial compartment, ICP was increased and CPP was decreased. The baseline levels of p(ti)O2, p(ti)CO2, and pH(ti) in the noninjured brain tissue showed more heterogeneity compared to the findings in cerebrovenous blood. Both, p(ti)O2 and p(cv)O2 were significantly correlated to the induced CPP decrease. PCO2 was inversely correlated to the course of CPP in both measurement compartments. Temperature measurement showed a positive correlation with CPP in both compartments. These findings demonstrate that brain tissue oximetry and cerebrovenous PO2 measurement are sensitive to CPP changes. The newly available continuous parameters in multisensor probes could be helpful in interpreting findings of cerebral oxygen measurement in man by analyzing the interrelationship of these parameters.

[Artificial humidification of inspired gas--status of knowledge and technique]

Artificial humidification of inspired air serves to maintain or restore physiological heat and moisture conditions in the bronchial system in intubated or tracheotomized patients. The need to condition the respiratory gases in these patients is undisputed. The present paper reviews the pathophysiology and methods of the artificial active and passive humidifying of inspired gases. The various advantages and disadvantages of the individual methods and techniques of humidifying inspired gases are compared and discussed. Present-day medical knowledge indicates that passive artificial humidifying of respiratory gases (heat and moisture exchanger, HME) is adequate to meet most requirements for warming and moistening the inspiratory air in patients whose upper airways are devoid of natural conditioning of respiratory gases in consequence of intubation and tracheotomy. This applies to artificial ventilation in prehospital situations, artificial ventilation in anaesthesia and long-term artificial ventilation on the intensive care unit. With appropriate restrictions, the respiratory air of patients who breathe spontaneously via an artificial air vent (e.g. tracheal cannula) can also be conditioned by HME.