Linear and non-linear heart rate metrics for the assessment of anaesthetists' workload during general anaesthesia.

BACKGROUND: Excessive workload may impact the anaesthetists' ability to adequately process information during clinical practice in the operation room and may result in inaccurate situational awareness and performance. This exploratory study investigated heart rate (HR), linear and non-linear heart rate variability (HRV) metrics and subjective ratings scales for the assessment of workload associated with the anaesthesia stages induction, maintenance and emergence. METHODS: HR and HRV metrics were calculated based on five min segments from each of the three anaesthesia stages. The area under the receiver operating characteristics curve (AUC) of the investigated metrics was calculated to assess their ability to discriminate between the stages of anaesthesia. Additionally, a multiparametric approach based on logistic regression models was performed to further evaluate whether linear or non-linear heart rate metrics are suitable for the assessment of workload. RESULTS: Mean HR and several linear and non-linear HRV metrics including subjective workload ratings differed significantly between stages of anaesthesia. Permutation Entropy (PeEn, AUC=0.828) and mean HR (AUC=0.826) discriminated best between the anaesthesia stages induction and maintenance. In the multiparametric approach using logistic regression models, the model based on non-linear heart rate metrics provided a higher AUC compared with the models based on linear metrics. CONCLUSIONS: In this exploratory study based on short ECG segment analysis, PeEn and HR seem to be promising to separate workload levels between different stages of anaesthesia. The multiparametric analysis of the regression models favours non-linear heart rate metrics over linear metrics.

Sleep scoring made easy-Semi-automated sleep analysis software and manual rescoring tools for basic sleep research in mice.

Studying sleep behavior in animal models demands clear separation of vigilance states. Pure manual scoring is time-consuming and commercial scoring software is costly. We present a LabVIEW-based, semi-automated scoring routine using recorded EEG and EMG signals. This scoring routine is •designed to reliably assign the vigilance/sleep states wakefulness (WAKE), non-rapid eye movement sleep (NREMS) and rapid eye movement sleep (REMS) to defined EEG/EMG episodes.•straightforward to use even for beginners in the field of sleep research.•freely available upon request. Chronic recordings from mice were used to design and evaluate the scoring routine consisting of an artifact-removal, a scoring- and a rescoring routine. The scoring routine processes EMG and different EEG frequency bands. Amplitude-based thresholds for EEG and EMG parameters trigger a decision tree assigning each EEG episode to a defined vigilance/sleep state automatically. Using the rescoring routine individual episodes or particular state transitions can be re-evaluated manually. High agreements between auto-scored and manual sleep scoring could be shown for experienced scorers and for beginners quickly and reliably. With small modifications to the software, it can be easily adapted for sleep analysis in other animal models.

Burst suppression-MAC and burst suppression-CP50 as measures of cerebral effects of anaesthetics.

BACKGROUND: MAC (minimum alveolar concentration of an inhaled anaesthetic) and CP50i (minimum plasma concentration of i.v. anaesthetics) are well-established measures to compare potencies of anaesthetics. The underlying clinical endpoint immobility reflects mainly effects of anaesthetics on the spinal cord, which limits the use of this measure for comparison of effects on the main target organ of general anaesthesia--the brain. The present study determines the median concentration of sevoflurane, isoflurane, and propofol that induce the onset of electroencephalogram (EEG) suppression ('silent second'): MACBS and CP50BS. METHODS: Fifty-five unpremedicated patients (ASA physical status of I or II) undergoing elective surgery were randomly assigned to receive general anaesthesia with sevoflurane, isoflurane, or propofol. A two-channel EEG was continuously recorded to identify 'silent second'. Independent cross-over pairs were analysed using the 'Dixon's up-and-down' method, and MACBS/CP50BS values were calculated by logistic regression. RESULTS: CP50BS was 4.9 µg ml(-1) for propofol. MACBS was 2.9 vol% for sevoflurane and 1.5 vol% for isoflurane. CP50BS of propofol was less than one-third of CP50i, whereas MACBS of sevoflurane was >1.4-fold of MAC; MACBS of isoflurane was 1.3-fold of MAC. CONCLUSIONS: Immobility and cerebral effects reflect different entities of anaesthetic action. The median concentration of anaesthetic drug (volatile or i.v. agent) required to induce 'silent second' might be a more useful metric than the median concentration required to prevent movement in response to a surgical stimulus in order to compare relative potencies of anaesthetic agents on the brain. Advantage of the 'silent second' is an easy identification of this endpoint, while such a deep level is not required for clinical anaesthesia.

Plasma oxytocin and vasopressin do not predict neuropeptide concentrations in human cerebrospinal fluid.

The involvement of the neuropeptides oxytocin (OXT) and vasopressin (AVP) in human socio-emotional behaviours is attracting increasing attention. There is ample evidence for elevated plasma levels upon a wide variety of social and emotional stimuli and scenarios, ranging from romantic love via marital distress up to psychopathology, with cause versus consequence being largely unclear. The present study examined whether plasma levels of both OXT and AVP are reflective of central neuropeptide levels, as assumed to impact upon socio-emotional behaviours. Concomitant plasma and cerebrospinal fluid (CSF) samples were taken from 41 non-neurological and nonpsychiatric patients under basal conditions. Although OXT and AVP levels in the CSF exceeded those in plasma, there was no correlation between both compartments, clearly suggesting that plasma OXT and AVP do not predict central neuropeptide concentrations. Thus, the validity of plasma OXT and AVP as potential biomarkers of human behaviour needs further clarification.

Cardiopulmonary resuscitation performance during simulator-based trainings: a comparative retrospective analysis of adherence to 2005 and 2010 guidelines.

BACKGROUND: New cardiopulmonary resuscitation (CPR) guidelines have been published in 2010 emphasizing the importance of minimizing interruptions during chest compression. The aim of our study was to compare the simulator-based CPR training performance of physicians not specialized in anaesthesia and intensive care nurses before and after implementation of new resuscitation guidelines. METHODS: In autumn 2010, a total of 74 scenarios during six 1.5 day simulation-based CPR trainings were performed. Four of them were conducted after the implementation of the 2010 guidelines. During each simulated scenario a programmed script standardized the conditions of the simulator and its reactions on the trainees' actions. CPR relevant parameters were extracted on the basis of the simulator's log files and no-flow-time fraction and median cardiac output of the simulator were calculated. Results before and after the guideline implementation were compared using the Wilcoxon Two Sample Test. RESULTS: Thirty-four out of 74 scenarios were included into the analysis. During training according to the 2010 guidelines, the no-flow-time fraction was lower (median: 21.8% [IQR: 16.1-27.1%] vs. 29.1 % [IQR: 25.0-30.9 %]; P=0.04). The median cardiac output increased from 1.60 L/min-1 [IQR: 1.50-1.65 L/min-1] to 1.90 L/min-1 [IQR: 1.80-2.10 L/min-1]; P<0.001) when the CPR training was conducted according to the 2010 resuscitation guidelines. CONCLUSION: Non-anesthesiological physicians and intensive care nurses training demonstrated an improved CPR performance in a high-fidelity human patient simulator with respect to the median cardiac output and duration of no-flow-time when 2010 CPR guidelines were applied.

Alterations in rotation thromboelastometry (ROTEM®) parameters: point-of-care testing vs analysis after pneumatic tube system transport.

BACKGROUND: Thromboelastometry as point-of-care (POC) testing enables the analysis of the clotting process at the bedside, providing rapid results to guide haemostatic therapy. However, POC testing utilizes medical staff who are managing critically ill patients, as non-laboratory personnel may not be sufficiently trained to run the devices. To resolve these problems, thromboelastometry can be performed in the central laboratory and rapid transport of samples can be accomplished via a pneumatic tube system (PTS). This study compares thromboelastometry parameters of blood samples analysed immediately with those analysed after PTS transport. METHODS: In patients with normal haemostasis, two arterial blood samples were collected from each patient (n=92) in citrated plastic tubes to investigate the assays INTEM (n=35), EXTEM (n=27), and FIBTEM (n=30). One blood sample was analysed immediately, the other sample after PTS transport. Thromboelastometry was performed using a single ROTEM(®) device. RESULTS: The mean clot firmness values were significantly lower for PTS samples in both the INTEM (-0.7 mm cf. -1.1 mm) and EXTEM (-1.4 cf. -1.7 mm) assays. INTEM coagulation time (CT) was significantly lower in PTS samples with a mean difference of -13 s. EXTEM CT was significantly higher in PTS samples with a mean difference of +3.9 s. CONCLUSIONS: Thromboelastometry parameters of blood samples analysed after PTS transport are significantly altered compared with those analysed immediately. However, in patients with normal haemostasis, the alterations were small and without clinical consequence, implying that analysis after PTS transport is an acceptable alternative to prompt analysis at the bedside. Further studies should focus on patients with impaired haemostasis.

Monitors of the hypnotic component of anesthesia - correlation between bispectral index and cerebral state index.

BACKGROUND: The current study examines whether analysis of identical EEG data results in a high correlation coefficient of BIS and CSI values during all anesthetic levels and assesses the concordance of both EEG monitors for displaying the level of anesthesia as defined by the manufacturers. METHODS: EEG data of 40 patients undergoing elective surgery under general anesthesia with either sevoflurane/remifentanil or propofol/remifentanil were replayed to an EEG player and reanalysed by a BIS A-2000® monitor and a Cerebral State Monitor. Further, research into differences between CSI and BIS index values was performed, e.g., extraction of differences of ≥ 10 and ≥ 20 index points and of the EEG length with differing index values. RESULTS: The overall correlation coefficient was 0.68 without significant difference between propofol or sevoflurane group. In 51.8% of all recordings, both EEG monitors agreed in their classification of the anesthetic level. The number and length of differing index pairs was influenced by varying time delays of index calculation and different algorithms of index computation. CONCLUSION: In contrast to previous studies, our current approach combines the following conditions: analysis on basis of identical underlying EEG data from deep to light anesthesia, no guidance of anesthetic administration by one of the EEG-based monitors, avoidance of simultaneous EEG readings and the use of two different anesthetic regimens. Though the result of EEG analysis during anesthesia is similar with both monitors, CSI performance during propofol anesthesia was superior to sevoflurane anesthesia. Consequently, a lower agreement of classification of anesthetic levels between BIS and CSI was reached with the use of sevoflurane. Thus, CSI calculation seems not to be independent from anesthetic agent.

Visual attention of anaesthetists during simulated critical incidents.

BACKGROUND: Situation awareness (SA) is considered to be an important non-technical skill for delivering safe anaesthesia. The spatial distribution of visual attention (VA) is an underlying process for attaining adequate SA. In the present study, a novel technology was used to assess the distribution of VA in anaesthetists delivering anaesthesia. The impact of a critical incident on VA in relation to individual experience is analysed in a descriptive and exploratory manner. METHODS: Fifteen anaesthetists induced general anaesthesia in a full-scale simulator while wearing a head-mounted eye-tracking camera system. After an uneventful session, workload was increased in a randomized order by simulation of a critical incident in the second or third session. Eye tracking was used for the assessment of individual's distribution of VA to monitors, patient, and environment. A post hoc video analysis revealed information about the spatial distribution of VA. Descriptive statistics and exploratory analysis were used. RESULTS: Twenty per cent of VA was directed to the patient monitor (30% during critical incident scenarios, P=0.003). The more experienced anaesthetists (more than 2 yr of work experience) increased the amount of time dedicated to manual tasks from 21% to 25% during critical incidents, whereas the less experienced decreased from 20% to 14% (P=0.061). CONCLUSIONS: Distribution of attention is different during anaesthesia induction with critical incidents compared with uneventful anaesthesia induction. Less experienced anaesthesia providers spend more time on monitoring tasks. Further investigation in confirmatory designs is needed.

Eye tracking for assessment of workload: a pilot study in an anaesthesia simulator environment.

BACKGROUND: Workload assessment is an important tool for improving patient safety in anaesthesia. We tested the hypothesis that heart rate, pupil size, and duration of fixation increase, whereas saccade amplitude decreases with increased workload during simulated critical incidents. METHODS: Fifteen trainee anaesthetists participated in this randomized cross-over trial. Each participant used a head-mounted eye-tracking device (EyeSeeCam) during induction of general anaesthesia in a full-scale simulation during three different sessions. No critical incident was simulated in the first session. In a randomized order, workload was increased by simulation of a critical incident in the second or third session. Pupil size, duration of fixations, saccadic amplitude, and heart rate of each participant and the simulator conditions were recorded continuously and synchronized. The data were analysed by paired sample t-tests and mixed-effects regression analysis. RESULTS: The findings of the second and third sessions of 11 participants were analysed. Pupil diameter and heart rate increased simultaneously as the severity of the simulated critical incident increased. Allowing for individual effects, the simulator conditions explained 92.6% of the variance in pupil diameter and 93.6% of the variance in heart rate (both P<0.001). The duration of fixation decreased with increased workload. The saccadic amplitude remained unaffected by workload changes. CONCLUSIONS: Pupil size and heart rate reflect workload increase within simulator sessions, but they do not permit overall workload comparisons between individuals or sessions. Contrary to our assumption, the duration of fixation decreased with increased workload. Saccade amplitude did not reflect workload fluctuations.

The mu-opioid receptor agonist remifentanil induces acute dysphoria irrespective of its analgesic properties.

Mu-opioidergic agonists are believed to induce euphoria, whereas kappa-agonists are thought to lead to dysphoria. Our study investigated mood effects of remifentanil, a mu-receptor opioid agonist, in healthy male volunteers. Moreover, we examined interactions between mood and pain. Three conditions were investigated in 21 volunteers: saline, 0.05 and 0.15 microg kg(-1) min(- 1) remifentanil. Each condition was investigated during non-painful heat and during painful heat stimulation. Mood was measured with the von Zerssen's mood scale (Bf-S score) and pain intensity using a Visual Analogue Scale (VAS). High Bf-S scores are reflecting discontent and dysphoria. Changes were tested for significance using a linear mixed model approach. Remifentanil significantly increased Bf-S scores during painful heat (+91.4%), indicating a negative mood effect, although it reduced VAS scores of painful heat intensity (-49.0%). The type of sensory stimulation (non-painful versus painful) had no effect on mood. There was no interaction between remifentanil dose and type of stimulation. Our results provide evidence for negative mood effects of remifentanil. These effects occur with and without pain. Taken into account that remifentanil reduces pain, one could have expected analgesia-related amelioration of mood instead. In clinical practice, these remifentanil effects should be considered and a comedication might be advisable.

Time delay of electroencephalogram index calculation: analysis of cerebral state, bispectral, and Narcotrend indices using perioperatively recorded electroencephalographic signals.

BACKGROUND: Monitoring of anaesthetic depth with EEG-derived indices may detect EEG changes associated with awareness and thereby help to decrease the incidence of intraoperative awareness with postoperative recall. All currently available monitors need varying time periods to calculate a new index when reacting to changes in anaesthetic depth. The exact time delay for calculation of new index values is unknown. In a previous study, we used simulated EEG signals and found considerable time lags for the cerebral state index (Danmeter, Odense, Denmark), the bispectral index (Aspect Medical Systems Inc., Newton, MA, USA), and the Narcotrend index (MonitorTechnik, Bad Bramstedt, Germany). The aim of this study was to investigate whether the time delays observed with simulated EEG signals also applied to real EEG data. METHODS: We used perioperatively recorded EEG data from a database corresponding to the awake state, general anaesthesia, and suppression of cortical activity, respectively. After a switch from one state of consciousness to another, the time necessary for all indices to adjust the index value to the underlying input signal was measured. RESULTS: We found time delays for all indices between 24 (7) and 122 (23) s before the new state was indicated. In accordance with our previous results, these time delays were not constant and depended on the particular starting and target index value. Results were different for decreasing and increasing values. CONCLUSIONS: Our results may show a limitation of the value of electronic EEG indices in prevention of awareness with recall. Furthermore, due to different time delays for ascending and descending values, the results of pharmacodynamic studies may be influenced by this phenomenon.

Informatics and medicine--from molecules to populations.

OBJECTIVES: To clarify challenges and research topics for informatics in health and to describe new approaches for interdisciplinary collaboration and education. METHODS: Research challenges and possible solutions were elaborated by scientists of two universities using an interdisciplinary approach, in a series of meetings over several months. RESULTS AND CONCLUSION: In order to translate scientific results from bench to bedside and further into an evidence-based and efficient health system, intensive collaboration is needed between experts from medicine, biology, informatics, engineering, public health, as well as social and economic sciences. Research challenges can be attributed to four areas: bioinformatics and systems biology, biomedical engineering and informatics, health informatics and individual healthcare, and public health informatics. In order to bridge existing gaps between different disciplines and cultures, we suggest focusing on interdisciplinary education, taking an integrative approach and starting interdisciplinary practice at early stages of education.

[Postoperative acute mitral regurgitation. Unexpected finding after minor non-cardiac surgery]. / Akute perioperative Mitralklappeninsuffizienz. Unerwarteter Befund nach nichtkardiochirurgischem Bagatelleingriff.

This report describes the case of a 59-year-old man who was scheduled for general anesthesia with propofol, sufentanil and sevoflurane for removal of a metal implant. The patient was classified as American Society of Anesthesiologists (ASA) II status because of an asymptomatic mitral valve prolapse and medically treated arterial hypertension. During induction of narcosis a pulsoxymetrically measured inadequate increase in oxygen saturation after preoxygenation was noticed and a moderate respiratory obstruction occurred intraoperatively, but anesthesia was uneventfully completed and the patient was extubated. However, 3 h later the patient developed severe dyspnea, hypoxia, tachycardia and arterial hypotension. Physical examination revealed a new grade 4/6 systolic murmur radiating to the axilla and X-ray showed bilateral pulmonary edema. Neither electrocardiographic nor biochemical manifestations of acute myocardial infarction were identified but transthoracic echocardiography revealed fluttering of the posterior leaflet of the mitral valve with grade III regurgitation and dilation of the left atrium. Coronary angiography was normal and left ventriculography confirmed severe mitral regurgitation. Mitral valve repair was successfully performed 22 h after presentation of symptoms. Mitral regurgitation is a common finding on echocardiography, seen to some degree in over 75% of the population. The etiology of mitral valve insufficiency which can be caused by pathologic changes of one or more of the components of the mitral valve, including the leaflets, annulus, chordae tendineae, papillary muscles, or by abnormalities of the surrounding left ventricle and/or atrium are discussed. Rupture of mitral chordae tendineae is infrequent and causes acute hemodynamic deterioration and needs corrective surgery. Valve replacement should be performed only if mitral valve repair is not possible. Echocardiography is an invaluable tool in determining the severity of regurgitation, the integrity of the mitral valve apparatus, the extent of left ventricular enlargement, and the ejection fraction. Acute mitral valve regurgitation caused by a rupture of chordae tendineae should be considered in the differential diagnosis of perioperative acute pulmonary edema.

[Current level of patients' knowledge of anaesthesiology]. / Zum Kenntnisstand von Patienten über die Aufgaben der Anästhesiologie.

The anaesthesiologist's competence in anaesthesia, intensive care medicine, pain therapy and emergency medicine is accepted throughout the medical society. Nevertheless, during the last decades patient surveys demonstrated a considerable lack of information of the responsibility of our work. By continuous education and information anaesthesiologists have aimed to improve the information and decision-making process for the patient. This multicentre trial was designed to investigate the current public view on our profession in seven German hospitals. In-hospital patients were asked to fill out a standardised questionnaire prior to the anaesthesia premedication visit and a total of 692 questionnaires (77%) were analysed. Results demonstrated an increased level of knowledge for anaesthesia (>95%), intensive care medicine (74%), and pain therapy (50% acute pain; 32% severe pain). In the case of emergency medicine (10%) the in-hospital and out-of-hospital responsibilities were not clear among patients. We conclude that the continuous distribution of information in recent years has contributed to improving patients' knowledge on interdisciplinary responsibilities. Future efforts should focus on the gaps in patient's knowledge to allow the patient to ask the right questions necessary for decision-making.

[Risks and complications of epidural neurolysis -- a review with case report]. / Schwerwiegende Risiken und Komplikationen der epiduralen Neurolyse nach Racz.

Racz's minimal invasive epidural catheter procedure, also known as "epidural neuroplasty" is not only utilized in patients suffering from failed spine surgery ("failed back surgery syndrome") but also increasingly applied to non-surgical back pain patients to prevent chronification or deterioration. Its hypothesized principle of action is local epidural lysis of adhesions, neurolysis of vertebral nerve roots and local lavage of proinflammatory mediators by repeated injection of local anesthetics, corticosteroids, hyaluronidase and hypertonic saline solution. However adverse events are well known to occur in epidural neuroplasty. Complications of epidural neuroplasty are due to the procedure itself or due to specific drugs-related side effects. Unintended dural puncture, administration of the drugs to the subarachnoid or subdural space, catheter shearing, infection and severe hemodynamic instability during application are most commonly observed adverse events. Complications related to the procedure itself occur immediately, while complications relating to drug administration show later onset. Within this context, we report a case of severe meningitis with neurologic sequelae in a patient who received Racz catheter-treatment for unspecific low-back pain and provide an overview of the literature on other potential severe complications. As a consequence, we recommend that the Racz catheter procedure as yet should be restricted to controlled clinical trials with rigorous inclusion- and exclusion criteria.

[Perioperative pain therapy for knee endoprosthetics]. / Perioperative Schmerztherapie in der Kniegelenkendoprothetik.

Total knee arthroplasty (TKA) is associated with significant postoperative pain. Adequate analgesics and techniques are required for early mobilization, continuous passive motion and intensified physical therapy as well as for high-quality postoperative analgesia.However, in the immediate postoperative setting the excessive nociceptive input can be blocked by using doses which are most frequently associated with adverse effects like dizziness, nausea and vomiting, sedation and risk of respiratory depression. The use of peripheral nerve blocks is recommended after orthopaedic surgery. After TKA, the continuous "3 in 1 nerve block" has been proven to be more effective than conventional patient controlled intravenous opioid therapy as well as than epidural analgesia accompanied by side effects. Postoperative analgesic techniques influence surgical outcome, duration of hospitalization and re-convalescence. The use of regional analgesia after TKA may initially lead to higher costs but it is counterbalanced by a reduction in morbidity and mortality, decrease in hospitalization, improved re-convalescence and a better functional outcome.

Awareness and the EEG power spectrum: analysis of frequencies.

BACKGROUND: Power spectral analysis is a well-established method for the analysis of EEG signals. Spectral parameters can be used to quantify pharmacological effects of anaesthetics on the brain and the level of sedation. This method, in numerous variations, has been applied to depth of anaesthesia monitoring and has been incorporated into several commercially available EEG monitors. Because of the importance of EEG spectral analysis, we evaluated the performance of each frequency in the power spectrum regarding detection of awareness. METHODS: Ninety artefact-free EEG segments of length 8 s were obtained from a database that contains perioperatively recorded EEG data. For the present analysis, EEG data were selected from 39 patients with propofol-remifentanil or sevoflurane-remifentanil anaesthesia with a period of awareness. Half of the EEG segments were recorded during periods of awareness as defined by an adequate response to the command 'squeeze my hand'. The other half were from unresponsive patients. The power spectral density was calculated for each segment. The performance of each frequency bin of the power spectrum as a detector of awareness was assessed with a remapped prediction probability rPK, i.e. the prediction probability PK mapped to a range of 0.5-1. RESULTS: The remapped prediction probability was high (rPK>0.8) for low frequencies (<15 Hz) and for high frequencies (>26 Hz), with a minimum (rPK<0.55) at 21 Hz. Indentations in the 'performance spectrum' occur at the power-line frequency (50 Hz) and its harmonics and at 78 Hz, probably caused by the continuous impedance measurement of another device used in parallel. With the exception of the indentations, the remapped prediction probability of the high frequencies (>35 Hz) was >0.95. CONCLUSIONS: The best performance for the detection of awareness was achieved by EEG power spectral frequencies from >35 Hz up to 127 Hz. This frequency band may be dominated by muscle activity. The frequency band between 15 and 26 Hz may be of limited value, as reflected by lower rPK values.

[Treatment of anaphylactic reactions: a review of guidelines and recommendations]. / Therapie anaphylaktischer Reaktionen: Synopsis bestehender Leitlinien und Empfehlungen.

In the present review, guidelines and recommendations for the treatment of anaphylactic reactions are presented and evaluated. Herefore, publications of German and non-German societies and expert groups have been selected and, in addition to that, we have chosen a number of articles that were cited frequently and, as far as we are concerned, have a relevant meaning for this theme. None of the traditionally applied remedies - epinephrine and intravascular volume, histamine receptor blockade, inhaled betamimetics and steroids - have been proven efficacious by means of evidence-based medicine. Due to the variability of the symptoms of anaphylaxis, it is widely accepted that such a clinical proof is unlikely to come. In contrast to this, there is lack of a consense as to substantial elements of the therapy, above all with regard to dosage and application mode for epinephrine and likewise concerning amount and kind of intravenous fluids. Hence, the physician in charge has to face the necessity either to follow the guidelines of his institution (if there are any) or to blend his own therapeutic regime according to his own convictions.