Blood volume is normal after pre-operative overnight fasting.

BACKGROUND: Pre-operative fasting is assumed to cause a deficit in intravascular blood volume (BV), as a result of ongoing urine production and insensible perspiration. Standard regimes consist of volume loading prior or simultaneous to any anaesthetic procedure to minimise the risk of hypotension. However, fluid overload in the context of major abdominal surgery has been shown to deteriorate patient outcome. Our study aimed to quantify total intravascular BV after fasting by direct measurements and to compare it with calculated normal values in comparable non-fasted patients. METHODS: After 10 h of fasting, total plasma volume (PV) and red cell volume (RCV) were measured via the double-label technique (indocyanine green dilution and erythrocytes labelled with fluorescein, respectively) following induction of general anaesthesia in 53 gynaecological patients suffering from malignoma of the cervix. The corresponding normal values were calculated individually from age, body height and body weight. RESULTS: Measured BV, RCV and PV after fasting were 4123+/-589, 1244+/-196 and 2879+/-496 ml, respectively. The differences to the corresponding calculated normal values were not significant (3882+/-366, 1474+/-134 and 2413+/-232 ml, respectively). The measured haematocrit reflected a slight anaemic state (0.35+/-0.03). CONCLUSION: Our data suggest that even after prolonged pre-operative fasting, cardio-pulmonary healthy patients remain intravascularly normovolaemic. Therefore, hypotension associated with induction of general or neuraxial anaesthesia should perhaps be treated with moderate doses of vasopressors rather than with undifferentiated volume loading.

Impact of the time window on plasma volume measurement with indocyanine green.

Recent reports have questioned the accuracy of the indocyanine green dilution technique for measuring plasma volume. Our objective was to evaluate the impact of different time windows for monoexponential extrapolation. We retrospectively analysed 31 indocyanine green decay curves to investigate the problem in principle (group 1) and prospectively performed another 21 plasma volume measurements to estimate its practical impact (group 2). To monoexponentially extrapolate back to the specific extinction at the time of dye injection, two different time windows were applied to each decay curve, comparing the plasma volumes resulting from sampling within a short (5 min) period of time. Extrapolating back from the longer period led to a higher apparent plasma volume relative to the shorter period in both groups, the difference being 348 +/- 171 ml (group 1) and 384 +/- 131 ml (group 2; mean +/- SD; p < 0.05 each). This result was due to a reliable monoexponentiality of decay only up to the 5th min after dye injection. Thus, to estimate the initial distribution space of indocyanine green via monoexponential extrapolation, the first linear kinetic of indocyanine green decay should be taken.

Group A streptococcal toxic shock syndrome with severe necrotizing fasciitis following hysterectomy--a case report.

In the last 10 years an increasing number of cases of group A streptococcal toxic shock syndrome have appeared in various clinical settings. The manifestation of this syndrome includes rapidly progressive multiorgan failure and soft-tissue necrosis. This report presents a case of streptococcal toxic shock syndrome caused by Streptococcus pyogenes with severe necrotizing fasciitis of the abdominal wall following hysterectomy. Aggressive surgical intervention with debridement of all necrotic tissue necessitated resection of the complete abdominal wall (skin, subcutaneous tissue, muscle and peritoneum). The abdominal wall defect was covered with free myocutaneous flaps and split-skin grafts. Optimal treatment, including adequate antibiotic therapy and radical surgical intervention, is an indispensable prerequisite of successful outcome.

The syndrome of inappropriate secretion of antidiuretic hormone (SIADH)--treatment with lithium.

Two patients with SIADH after brain trauma are described. Features of SIADH are "inappropriate" antidiuresis and excessive natriuresis with negative sodium balance resulting in hyponatremia and plasma hypoosmolality which may lead to cerebral dysfunction. Oral lithium carbonate was beneficial in both patients. With plasma levels of lithium around 1 mmol/l a temporary impairment of renal concentrating ability and antinatriuresis with normalization of plasma sodium and plasma osmolality was observed. The SIADH subsided about 4 months after the original trauma, long after gross neurological symptoms had resolved.

Determination of plasma volume with indocyanine green in man.

We investigated the feasibility of using indocyanine green (ICG) for plasma volume (PV) determination in man. Duplicate PV measurements were carried out in 23 healthy subjects to test repeatability. ICG (0.25 mg/kg) was injected intravenously into one arm and venous blood was withdrawn from the opposite arm. Optical density of plasma samples from minute 3 to 9 was measured in a densitometer. ICG concentration at injection time was determined by monoexponential extrapolation. The mean (SD) difference (MD) was -23 ml (183) or -0.6% (5.7%). Linear regression revealed PV2 = 0.92.PV1 + 226 (r = 0.92). The PV values corresponded well with data from other studies. In 26 surgical patients PV was determined using two methods: 1) the same as in healthy subjects and 2) using a modification of this method in whole blood (PVB). For PVB measurement blood was drawn through a cuvette-densitometer from an arterial line. Calculations were the same as in PV determination except for the use of hematocrit to achieve plasma concentrations of ICG from whole blood. In patients MD were -53 ml (144) or -1.3% (4.3) for PV and -19 ml (161) or -0.3% (5.1) for PVB. Comparing PVB and PV revealed MD = -113 ml (149) or -3.3% (4.2). The whole blood method is easier to perform and reduces blood waste to almost zero. In conclusion, ICG is a suitable tracer for PV determination.

Development of a knowledge-base for automatic monitoring of renal function of intensive care patients over time.

Renal dysfunction is a major problem in the management of critically ill patients. Monitoring of renal parameters over time is a prerequisite for detection of any significant deterioration of kidney function. Thus, we developed a knowledge-base for the dynamic monitoring of renal function of critically ill patients. A database with renal parameters of 750 intensive care patients was analyzed for distribution of parameters within predefined intervals of the creatinine clearance. Additionally, a subgroup of 11 patients with (quite) normal renal function over 11 days was selected and the daily variability of renal parameters was analyzed. An interdisciplinary expert team selected a set of nine clinically relevant renal parameters and formulated, on the basis of the data analysis and the parameter set, eight definitions of renal function, which represent four levels of renal performance. These definitions were arranged into an hierarchical structure, considering only clinically relevant changes of renal function. A change from one functional state to another inside of 2 days indicates a relevant alteration of renal function. Monitoring of time courses can additionally be performed by statistical analysis of the daily variability of parameters and comparison with their 'normal' variability. Moreover, rules were established for the plausibility check of results and interpretations of single parameters and parameter sets formulated.

Total and ionized calcium levels during open heart surgery with two different pump priming solutions.

UNLABELLED: Changes of total (Ca) and ionized Ca-levels (Ca2+) were studied during open heart surgery in 18 patients. 9 patients (group A) had only crystalloid solutions as pump priming, the other 9 patients (group B) had 500 ml of citrated whole blood in the priming solution. For assessment of hemodilution hct and total plasma protein and plasma albumin were determined. Measurements were done preoperatively, before and after systemic heparinisation, during and after extracorporeal circulation (ECC) and on the first postoperative day. RESULTS: 1. Anticoagulation with 375 U/kg BW heparin had no effect on ionized calcium levels. 2. With onset of ECC (Ca) decreased by 30% in group A and by 20% in group B. (Ca2+), however, decreased by 20% in group A and by 35% in group B. The percentage of ionized calcium increased by 15% in group A whereas it decreased by the same amount in group B. This difference is contributed to the calcium binding effect of citrate added to pump priming in group B. Mechanisms of the relative increase of ionized calcium during ECC in group A, however, remain to be studied.

Metabolism of phosphate and calcium after severe accidental trauma.

Hypophosphatemia is a common finding during the first 4-5 days after severe accidental trauma. We demonstrated that hypophosphatemia after trauma is caused by a definite decrease in renal phosphate threshold (TmPO4/GFR), that is the theoretical plasma phosphate concentration at which all of the filtered phosphate is reabsorbed by the renal tubules and renal excretion of phosphate is close to zero. We speculated that the decrease in renal phosphate threshold could be due to an increased activity of PTH which in turn could be the result of ionized hypocalcemia. In 7 patients with severe and in 8 patients with moderate trauma, however, we found ionized calcium and PTH levels to be within normal limits. Total plasma calcium was below normal (1.90-2.00 mmol/l) up to 20 days after trauma, probably due to a decreased plasma albumin concentration (25-30 g/l). We conclude, that ionized hypocalcemia and consecutive stimulation of PTH is not the cause of decreased renal phosphate threshold after severe accidental trauma.

[CO2--emphysema in laparoscopic surgery. Changes in pulmonary CO2-elimination]. / CO2-Emphysem bei laparoskopischer Chirurgie. Veränderungen der pulmonalen CO2-Elimination.

We report on two patients with subcutaneous carbon dioxide (CO2) emphysema that developed during laparoscopic surgery with CO2 pneumoperitoneum (PP), in whom pulmonary elimination of CO2 (ECO2, Servo ventilator with integrated CO2 analyzer 930, Siemens) was continuously monitored. Patient 1 was a 61-year-old man with laparoscopic herniotomy. ECO2 immediately before PP was 120 ml/min x m2 and increased rapidly after 45 min PP to a maximum value of 340 ml/min x m2. At that time, minute ventilation had been increased from 7 to 11 l/min and PaCO2 had risen from 35 to 57 mm Hg. At the end of the procedure the patient showed excessive subcutaneous emphysema. Patient 2 was a 71-year-old woman in whom diagnostic laparoscopy was performed for staging of a pancreatic tumor. ECO2 immediately before PP was 140 ml/min x m2, increasing dramatically after 45 min PP to a maximum value of 529 ml/min x m2 (Fig. 1). At that time minute ventilation had been increased from 6.2 to 12.5 l/min and PaCO2 had risen from 40 to 77 mm Hg. PP was terminated and the patient was found to have extreme subcutaneous emphysema. She was mechanically ventilated for a further 40 min to normalize PaCO2 and ECO2. It seems reasonable to suppose that an increase in ECO2 by more than 100% of control during CO2-PP is an early sign of CO2 emphysema. In this situation hypercapnia is potentially life-threatening. Evidently, reabsorption of CO2 from loose connective tissue is far more rapid and effective than CO2 resorption from the peritoneal cavity.(ABSTRACT TRUNCATED AT 250 WORDS)

[Renal effects of dopamine in healthy adults with special reference to the excretion of phosphate and calcium]. / Renal Effekte von Dopamin bei gesunden Erwachsenen unter besonderer Berücksichtigung der Exkretion von Phosphat und Kalzium.

The intravenous application of 4 micrograms/kg/min dopamine (DA) over 3 h in 11 healthy volunteers resulted in an increase in inulin clearance and urine volume by about 10%, renal excretion of sodium and calcium being increased by DA by a factor of 5. We found a strong linear correlation between changes of renal excretion of sodium and calcium under DA (r = 0,90). The concentration of ionized calcium in whole blood was absolutely stable under DA in the range of 1.25 to 1.27 mmol/l. The application of the catecholamine also resulted in a significant reduction of plasma volume by a mean of about 10% and in a nonsignificant reduction of intravascular protein mass by 8%. The phosphaturic effect of DA was weak and unpredictable. We suppose that in the intact organism the pharmacologic effect of dopamine on the tubular handling of phosphate which seems to be experimentally proven, may be masked by other mechanisms with an antiphosphaturic action such as increased levels of growth hormone and/or insulin.

[Blood-oxygen analyzer boa 802 (author's transl)]. / Blutsauerstoff-Messgerät BOA 802

Experiences with a new blood oxygen analyzer (BOA 802, Dräger-Bio Marine) are reported. In the range up to 100 mm Hg data about 6 mm Hg to high were found compared with the AVL Gas Check. In the range between 100-300 mm Hg there was an increasing difference between values measured with the BOA 802 and a conventional oxygen electrode, however this does not seem to be of clinical relevance.

A framework for the knowledge-based interpretation of laboratory data in intensive care units using deductive database technology.

In co-operation with the Institute of Anaesthesiology of the Ludwig-Maximilians-University in Munich a computer-based system for the analysis and interpretation of renal function, fluid and electrolyte metabolism of critical care patients has been developed. This paper focuses on the requirements and implementation aspects of the knowledge-based interpretation for this particular system. Objective of the proposed approach is, to transform an enormous--and constantly increasing--amount of raw data available in modern intensive care units (ICUs) into relevant, patient-oriented information, which is easy to understand by the medical staff. The essential features of a knowledge-based system at an ICU are outlined. A system is described where these features are realized using deductive database technology as a specification paradigm and extended relational databases as an implementation platform. The integration into the hospital information system is highlighted.

Visualization of large datasets in intensive care.

At the "Institut für Anaesthesiologie der Ludwig-Maximilians-Universität" in Munich a computer-based system for the analysis and interpretation of renal function and fluid and electrolyte metabolism of critical care patients has been developed. This paper describes requirements and implementation aspects of the presentation of data to the physician. Key issue is, how to transform the enormous--and, as we all know, constantly increasing--amount of plain data available in modern intensive care units (ICUs) into relevant information which can be easily turned into therapeutic actions. These issues have been discussed in literature extensively over many years, but with the upcoming of moderately priced, though powerful graphical UNIX workstations an extended functionality is feasible.

[Electrolyte balance in major abdominal surgery. IV. Water diuresis under anesthesia and surgery (author's transl)]. / Elektrolytbilanzen bei grossen bauchchirurgischen Eingriffen IV. Wasserdiurese unter Narkose und Operation.

12 patients with major laparotomies were studied during anesthesia alone, during three hours of surgery and during the first two hours of recovery. We demonstrated a decrease in plasma potassium and plasma sodium concentration starting with anesthesia and development of a moderate metabolic acidosis. Plasma osmolality was stable during anesthesia and surgery, but slightly decreased in the early postoperative period. Urine formation and osmolar clearance as well as renal sodium and potassium excretion showed a rising tendency during operation, reaching their maximal values in the recovery room. Sodium balance was positive during and after surgery, and sodium retention amounted to about 75% of sodium infused. Urine-to-plasma-osmolality-ratio was 2,0 under anesthesia alone, decreased during surgery and reached control values in the recovery room. In 5 out of 12 patient studied we demonstrated a temporary water diuresis at different points of anesthesia and laparotomy and occasionally even in the postoperative period. This could be due to low plasma levels of ADH caused by relative hypervolemia in the absence of other stimuli of ADH-secretion.

[Sodium and water balance in the dog under halothane and methoxyflurane anesthesia (author's transl)]. / Natrium- und Wasserbilanz beim Hund im Wachzustand und unter verschiedenen Narkosebedingungen. II. Mitteilung: Halothan- und Methoxyflurannarkose

In our model of volume expanded dogs with an equilibrium between input and renal output of sodium and water halothane anesthesia (1,5 Vol.-% insp.) was performed. In deepening halothane anesthesia we found a progressive decrease of mean aortic pressure, GFR and renal sodium and water excretion. There was a strong correlation between GFR and sodium excretion. With a high GFR significantly more sodium was excreted under halothane, whilst reduction of GFR led to an overproportional decrease of sodium excretion. Urine osmolality, too, depended on GFR under halothane. The results of methoxyflurane anesthesia were quite similansion. Concentrations of inorganic fluoride in serum and urine, which we measured in these experiments, did not result in visible changes of sodium or water balance, compared with the conscious state.

Effects of acute hypercapnia and hypocapnia on plasma and red cell potassium, blood lactate and base excess in man during anesthesia.

In order to test the relationship between changes in plasma potassium concentration and pH changes of respiratory origin, we produced hypercapnia (mean PaCO2 71 mmHg = 9.5 kPa) in a group of 17 patients and hypocapnia (mean PaCO2 21 mmHg = 2.8 kPa) in another 20 patients during neurolept analgesia and intraabdominal operations. A control group of 19 patients was studied under normocapnia but otherwise identical conditions. During hypercapnia, serum potassium rose, deltaK/deltapH amounting to -0.82, -1.05 and -1.34 after 30, 60 and 90 min, respectively. During hypocapnia, serum potassium decreased, deltaK/deltapH being a little more negative than during hypercapnia (mean values -1.62, -2.44 and -1.60). Red cell potassium concentration decreased in all three groups to a similar extent. Blood lactate levels during hypercapnia decreased to 75% of control and during hypocapnia rose to a maximum of 186% of control. In order to obtain reasonable values for base excess in primarily respiratory acid-base disorders, it is necessary to use nomograms based on in vivo ECF-CO2-titration curves. With this premise, hypercapnia or hypocapnia in our patients was not associated with significant changes in base excess.

[Pulmonary CO2 elimination in laparoscopic cholecystectomy. A clinical study]. / Pulmonale CO2-Elimination bei laparoskopischer Cholezystektomie. Eine klinische Untersuchung.

METHODS: We measured pulmonary elimination of carbon dioxide (VCO2), end-tidal and arterial CO2 tensions (PETCO2, PaCO2), deadspace ventilation (VD/VT), and arterial oxygen tension (PaO2) using a Siemens 930 CO2 analyzer incorporated into a servoventilator and arterial blood gas analyses, respectively, in 31 patients undergoing laparoscopic cholecystectomy with a median duration of pneumoperitoneum (PP) of 60 min. RESULTS: During the first 30 min of PP VCO2 increased significantly by a mean of 30% (Fig. 1). At the same time, with constant minute ventilation PETCO2 und PaCO2 increased by about 8 mm Hg each (Fig. 3, Table 1). In a subgroup of 10 patients who could be observed for up to 75 min of PP, we found a stepwise increase in minute ventilation with no further increase in PETCO2 and PaCO2 after 30 min PP, but a slowly rising VCO2 (Fig. 2). Arterial-to-end-tidal CO2 tension difference (Pa-PETCO2) remained constant at about 4 mm Hg with institution and during the course of PP (Fig. 4), as did VD/VT at a median value of 0.38-0.40 (Fig. 5). PaO2 (FIO2 = 0.5) did not change significantly with PP (Table 1). With desufflation we found a short-term increase in VCO2 (Table 2). CONCLUSIONS: During PP, CO2 is reabsorbed from the peritoneal cavity. During the initial unstable phase with rising PaCO2, reabsorption of CO2 is the sum of increased pulmonary elimination of CO2 above baseline and uptake of CO2 into gas stores of the body. We estimated CO2 reabsorption to be on the order of 70 ml/min during the first 30 min of PP. During the later, stable phase, reabsorption of CO2 equals increased pulmonary elimination of CO2 above baseline and was estimated to be in the order of 90 ml/min in 10 patients with 30-75 min of PP (hatched area in Fig. 2). PET-CO2 corresponded well with PaCO2 in these patients. VD/VT and arterial oxygenation did not change significantly with institution or during the course of PP. Monitoring VCO2 probably is a useful aid in the early detection of CO2 emphysema (Fig. 6).

[Anaesthesia for primary cesarean section in a patient with an extensive cerebral arteriovenous malformation]. / Primäre Sectio caesarea. Anästhesie bei einer Patientin mit ausgedehnter zerebraler arteriovenöser Malformation.

We report the case of a 37-year-old primigravida with an extreme cerebral arteriovenous malformation which displaced almost the complete left hemisphere and was inoperable. The woman had already suffered an intracerebral bleeding from this malformation many years previously. In the 26th gestational week the perfusion of the umbilical artery decreased and therefore a cesarean section became necessary. During direct measurement of arterial blood pressure an epidural catheter was inserted. Mean blood pressure always remained between 90 and 110 mmHg, the neurologic state did not deteriorate perioperatively. The mother was monitored in the intensive care unit for 24 h and was then sent back to the maternity ward in a good condition. Two months later she came back to hospital with an acute severe headache. After CT-diagnosis of an acute subarachnoid hemorrhage she underwent an emergency craniotomy.

[The Stewart model. "Modern" approach to the interpretation of the acid-base metabolism]. / Das Stewart-Modell. "Moderner" Ansatz zur Interpretation des Säure-Basen-Haushalts.

About twenty years ago, Peter Stewart had already published his modern quantitative approach to acid-base chemistry. According to his interpretations, the traditional concepts of the mechanisms behind the changes in acid-base balance are considerably questionable. The main physicochemical principle which must be accomplished in body fluids, is the rule of electroneutrality. There are 3 components in biological fluids which are subject to this principle: a)Water, which is only in minor parts dissociated into H+ and OH-, b)"strong", i.e. completely dissociated, electrolytes, which thus do not interact with other substances, and body substances, such as lactate, and c)"weak", i.e. incompletely dissociated, substances. Peter Stewart strictly distinguished between dependent and independent variables and thus indeed described a new order of acid-base chemistry. The 3 dependent variables (bicarbonate concentration [Bic(-)], pH, and with this also hydrogen ion concentration [H(+)]) can only change if the 3 independent variables allow this change. These 3 independent variables are: 1. Carbon dioxide partial pressure, 2.the total amount of all weak acids ([A-] (Stewart called these ATOT), and 3.strong ion difference (SID). [A(-)] can be calculated from the albumin (Alb) and the phosphate concentration (Pi): [A(-)]=[Alb x (0.123 x pH - 0.631)] + [Pi x (0.309 x pH - 0.469)]. An apparent SID (or "bedside" SID) can be calculated using measurable ion concentrations: SID=[Na(+)] + [K(+)] - [Cl(-)]-lactate. Regarding the metabolic disturbances of acid-base chemistry, according to Stewart's terminology, changes in pH, [H(+)], and [Bic(-)] are only possible if either SID or [A(-)] itself changes. If, for example, SID decreases (e.g. in case of hyperchloremia), this increase in independent negative charges leads to a decrease in dependent negative charges in terms of [Bic(-)] resulting in acidosis (and vice versa). Therefore, according to Stewart, the decrease in SID during hyperchloremic acidosis results from the increase in serum chloride concentration and is the causal mechanism behind this acidosis. Contrary for example, a decrease in [A(-)] (e. g. during hypoalbuminemia) leads to an increase in [Bic(-)] and therefore to an alcalosis (and vice versa). Thus, by Stewart's approach, completely new acid-base disturbances, like "hyperchloremic acidosis" or "hypoalbuminemic alcalosis" (which, of course, can also exist in combination) can be detected, which had been unrecognised by the classic acid-base concepts. Consequently, Stewart's analysis can lead to a better understanding of the mechanisms behind the changes in acid-base balance.