[Realisation of material costs in anaesthesia. Alternatives to the reimbursement via diagnosis-related groups]. / Sachkostenerfassung in der Anästhesie. Alternativen zur fallbezogenen "DRG-konformen" Vergütung.

BACKGROUND AND GOAL: For reimbursement via diagnosis-related groups (DRG), lump compensation-based payment of medical cases in German hospitals requires a case-related measuring and billing of resources that has to be consistent with DRG guidelines. Only through this, can the real costs be compared with the standard costs as calculated by the hospital reimbursment system (InEK) on a case-related basis and the DRG-specific break-even level be identified. METHODS: In the present paper the authors introduce and validate two newly created alternative methods for case-related allocation of material costs in the field of anaesthesia. Method 1 allows online documentation of material costs via pre-defined anaesthesia standards. This full cost method is suitable for hospitals that have implemented an electronic hospital information system in their daily clinical documentation routine. For other hospitals method 2 could be applicable as the case-related allocation of material costs is done retrospectively based on the data collected in an electronic anaesthesia protocol record system (andoc, medlinq). RESULTS: Method 1 makes it possible to allocate 90.3% of anaesthesia-related material costs to a specific case corresponding to a Pearsson coefficient of 0.77. After iterative improvement through optimisation of modules the documentation quality could be raised to >98% and a Pearsson coefficient of 0.96. Although the expense for implementation and maintenance is considerable, the necessary documentation work for the clinician is low. Method 2 demands no further clinical effort in documentation and implementation and 49.1% of all material costs can be assigned on a case-related basis. CONCLUSIONS: The online documentation of material costs via predefined anaesthesia standards accounts for nearly all material costs in anaesthesia and only a negligible documentation effort is necessary for the clinician. Nevertheless, a complex and time-consuming configuration of standards and a continuous iterative alignment of the modules with the actual processes are required. Due to its process-orientated character, method 1 can also be used for workflow optimisation in terms of standard operating procedures (SOPs). Allocation of material costs with data from the electronic anaesthesia record system is a method that can be easily implemented but only a partial case relation is rendered possible.

[Implementation of an internal transfer pricing system for anaesthesia services]. / Implementierung einer internen Leistungsverrechnung über Anästhesieminuten.

Internal transfer pricing system (ITPS) of anaesthesia services is established to guarantee a close connection of delivered service and the budget of the department of anaesthesia. In most cases a time-based system is used with the pricing unit being calculated as the quotient from the enumerator "costs" divided by the denominator "anaesthesia time in minutes". The implementation of a transfer pricing system requires the identification of all relevant costs caused by the department of anaesthesia and a cost centre structure is needed which allocates all costs correctly according to their cause. The regulations regarding cost calculations as defined by the German DRG System should be considered. To generate valid data not only the necessary technical infrastructure is needed, but also detailed training of the staff and plausibility checks are needed to ensure correct and complete data. Subsequent agreements with the hospital administration are necessary in order to adjust the system if extrinsic cost increases occur. This paper gives a step-by-step guidance for the successful implementation of an internal transfer pricing system based on anaesthesia time.

[Mechanical interaction between patient and ventilator in biphasic positive airway pressure (BIPAP)--digital and mechanical simulations]. / Die mechanische Interaktion zwischen Patient und Respirator bei Biphasic Positive Airway Pressure (BIPAP) - Digitale und mechanische Simulationen.

OBJECTIVE: Biphasic Positive Airway Pressure (BIPAP) and the closely related Airway Pressure Release Ventilation (APRV) are characterised by asynchronous actions of ventilator and patient. Clinical observation and physiological reasoning suggest, that in BIPAP patient and ventilator can interact in various ways. This study was to elucidate the mechanical interaction. METHODS: Ventilation and interaction between patient and ventilator were analysed in digital and mechanical simulations of BIPAP with a variety of patient effort magnitudes and durations, machine pressures and phase durations, and passive respiratory system (RS) mechanics. RESULTS AND CONCLUSIONS: Patient efforts were most likely to effect a breath if they were strong relative to the machine pressure swing, and if they occurred late in a ventilator phase. Conversely, efforts occurring with or shortly after a machine pressure swing or relatively weak efforts were more or less ineffective. The postulated permanently unrestricted spontaneous breathing in BlPAP mode, although indeed assured in the technical sense, has to be qualified: Every change in machine pressure defines a new balance of the forces driving the RS, and the lung volume will approach a new elastic equilibrium volume ( = relaxation volume); the speed of this approach is determined by the time constant (tau = R x C) of the RS. Patient efforts are most effective when the RS is at or close to an equilibrium. An increase in the assisting machine pressure swing can unload the patient and assure a minimum ventilation, but it reduces the patient"s influence on ventilation and thus potentially patient comfort. In contrast, Automatic Tube Compensation (ATC), an assist component accelerating the RS by reducing resistances, combines unloading with more patient influence; this has to be weighed against the potential disadvantage of higher peak flows.

[The ProSeal-LM, a new variant of the laryngeal mask: description and first clinical results]. / Die ProSeal-LM, eine neue Variante der Larynxmaske: Beschreibung und erste klinische Erfahrungen.

The ProSeal-LMA is a modification of the laryngeal mask airway (LMA) invented by AIJ Brain. It differs from the known models in three major respects: An additional lumen extending into the tip of the cuff allows insertion of a gastric tube. A pocket immediately behind the cuff accommodates a finger or a siliconated metal introducer and thus facilitates insertion. An additional cuff at the dorsal aspect of the mask pushes the mask into a ventral direction and thus improves the seal around the glottic opening. Our experience after 8 months of clinical use and first data from an international multi-center-study (24 ProSeal-LMA/24 Standard-LMA) are reported. With a ProSeal-LMA insertion of a gastric tube is much easier and more reliable than with a Standard-LMA (24/24 patients vs. 2/24 patients). Judged from visibility of the oesophagus during fibre-endoscopy the position of the ProSeal-LMA is superior to that of the Standard-LMA. Both are equally well tolerated and handled. Most remarkable is a better seal for the ProSeal-LMA (pressure for a leak of 3 L/min: 31 mbar compared to 20 mbar (mean) for the Standard-LMA). Therefore the ProSeal-LMA seems suitable for anaesthesia procedures with IPPV, which up to now are a domain of endotracheal intubation.

Resistance of laryngeal mask airway and tracheal tube in mechanically ventilated patients.

We compared the airflow resistance of 7.5 and 8.5 mm internal diameter (i.d.) endotracheal tubes (ETTs) with that of a size 4 laryngeal mask airway (LMA). We thought that any difference in the resistance of the devices alone might be offset by the resistance of the larynx. Sixteen adult ASA physical status I and II patients (14 males, two females) undergoing general anaesthesia were anaesthetized and paralysed with intravenous propofol, ketamine and vecuronium. After insertion of the LMA, controlled ventilation (tidal volume 10 ml kg-1, frequency 12 min-1) was established with three different settings for inspiratory flow (5.5, 7.5 and 12.5 ml kg-1 s-1). Ventilation with the same settings was used after orotracheal intubation with an ETT of i.d. 7.5 mm (females) or 8.5 mm (males). The position of the LMA mask and the tip of the ETT were checked through a fibrescope. The resistance of the devices and, in case of the LMA, of the larynx, was derived by relating proximal and distal pressures (measured via catheters) to inspiratory flow. Four patients--young, tall men--had to be excluded from further study because of a leak around the LMA. In the remaining 10 males and two females, resistance of the LMA (mean (SD) at high flow, 1.19 (0.22) mbar.s litre-1 in males) was less than that of the 8.5 mm i.d. ETT (3.34 (0.52) mbar.s litre-1) (P < 0.01). However, the structures between the LMA and the trachea added another, highly variable, resistance component, so that the mean resistance of the LMA and larynx together was similar (in males: 3.20 (2.71) mbar.s litre-1) to that of the 8.5 mm ETT. In eight patients the epiglottis projected on to one-tenth to two-thirds of the distal opening of the LMA; this was in no case associated with greater resistance. Greater resistance occurred in two patients with a central LMA position and unobstructed view of the glottis and in one patient with marked lateral deviation. In conclusion, there is no clinically relevant difference between the resistance of a size 4 LMA plus that of the larynx and that of an 8.5 mm i.d. ETT.

[The practicability, patient comfort and efficiency of the pre-oxygenation device NasOral]. / Praktikabilität, Patientenkomfort und Effizienz des Präoxygenierungssystems NasOral.

OBJECTIVE: We examined the new NasOral-System (NOS; Logomed, Germany), which is designed for a fasten and more complete denitrogenization when compared to the use of a contemporary face-mask. The patient inhales oxygen via a nose mask and exhales via mouthpiece. Nose mask and mouthpiece have built-in one-way valves, resulting in an unidirectional gas flow (nasal-oral). METHODS: With approval of the local ethic committee, pre-oxygenation with both the NOS and a face mask (Laerdal) was studied in 50 adult patients. Midazolam 3.75-7.5 mg p.os was given for premedication. The NOS was studied in two different ways: the nose mask fastened by rubberband and with the nose mask held by hand. Prior to induction every patient received every system in a randomised manner. Semi-closed-anaesthetic circle-systems with a fresh-gas-flow of 10 litres/min were used. The FEO2 over 5 min of pre-oxygenation were recorded (AS-3, Datex). Speed and degree of the denitrogenization was documented by an external digital data-acquisition system. Practicability of the systems regarding the anaesthesists (n = 27) and patient comfort were evaluated by means of a standardized postoperative questionnaire. RESULTS: The hand-held NOS is definitely more effective and reliable than both the NOS fastened by rubber-band and the classical face mask: 80% of the hand-held NOS were able to achieve a FEO2 of > or = 0.8 compared to only 36% of the NOS fixed by rubber-band, face mask: 48%. FEO2 of > or = 0.8 was achieved with 52% of the hand-held NOS in 90 s, a time we consider practical for daily routine, whereas only 10% of the NOS fixed by rubberband and 14% of the face masks accomplished this threshold. A cooperative patient is an important condition when using the NOS: a strong premedication effect, absence of dentures, and patients who can not inspire via nose and expire via mouth involve impairment of the positive effects of the NOS. 21% of the anaesthesists felt disturbed by the NOS. 72% do not believe, that induction of anaesthesia will become more safe with the NOS. For 8 patients, breathing with the NOS was disagreeable (face-mask: 3 patients), 15 were disturbed by the nose part/mouth piece (face-mask: no patient). CONCLUSION: An acceptable FEO2 of > or = 0.8 can be achieved only without leakage of both the NOS and the face-mask. Therefore, routine FEO2-monitoring seems highly desirable. Efficiency of the hand-held NOS is much better than with the NOS fastened by rubberband or the face mask. However, even the hand-held NOS cannot guarantee for optimal denitrogenization. Practicability in daily use was poor, because a test of airway patency by manual ventilation prior to relaxation/intubation is not possible with the NOS. Using the device as a help in apnoic oxygenation seems useful.

Continuous positive airway pressure facilitates spontaneous breathing in weaning chronic obstructive pulmonary disease patients by improving breathing pattern and gas exchange.

OBJECTIVE: To elucidate the effects of continuous positive airway pressure (CPAP) on breathing pattern, gas exchange and the ability to sustain spontaneous breathing (SB) in chronic obstructive pulmonary disease (COPD) patients with dynamic hyperinflation. DESIGN: Prospective study with two randomised trials of SB without and with CPAP in each patient. SETTING: Medical intensive care units (ICUs) in two university hospitals. PATIENTS: Nine dynamically hyperinflated, intubated COPD patients recuperating from acute exacerbation. INTERVENTIONS: One SB trial with CPAP (5-7.5 cmH2O), one without (control) in each patient. MEASUREMENTS: airway opening pressure, gas flow and thus breathing pattern, oxygen uptake, carbon dioxide excretion, arterial blood gases, dyspnoea and respiratory drive (P100). RESULTS: With CPAP, intrinsic positive end-expiratory pressure (PEEPi) fell from 11.4 to 6.3 cm H2O (p < 0.05). Eight patients sustained SB with CPAP for the maximum time planned (30 min), one failed after 18 min. In contrast, only four patients successfully completed the control trial, the others failing after 5-18 min (p < 0.05). Dyspnoea-gauged on a visual analogue scale by five patients--was less severe or occurred later with CPAP. Breathing with CPAP tended to be slower (18.9 vs 22.2 min(-1), p < 0.05) and deeper (tidal volume 370 vs 323 ml). At the end of the control run, PaCO2 was higher (60 vs 55 mmHg, p < 0.05) and still rising while being stable at the end of the CPAP trial. CONCLUSION: CPAP helps severely ill COPD patients sustain SB. Apparently it does so by promoting slower, deeper breathing and thus facilitating carbon dioxide elimination.

Efficacy of noninvasive CPAP in COPD with acute respiratory failure.

Dynamic hyperinflation and the development of intrinsic positive end-expiratory pressure (PEEPi) are commonly observed in patients with severe chronic obstructive pulmonary disease (COPD) in acute respiratory failure. Previous studies have shown that externally applied PEEP reduces PEEPi and its adverse effects in mechanically-ventilated COPD patients. The purpose of this study was to determine the effects of graded amounts of continuous positive airway pressure (CPAP) on the degree of inspiratory effort, pattern of breathing, gas exchange, and level of dyspnoea in a group of spontaneously breathing, nonintubated COPD patients in acute hypercapnic respiratory failure. Ten COPD patients admitted to the intensive care unit in acute hypercapnic respiratory failure were studied. Inspiratory effort was measured by the tidal excursions of oesophageal (Poes) and transdiaphragmatic (Pdi) pressure. Inspiratory effort and both the pressure-time product for the diaphragm (integral of Pdi-dt) and for the inspiratory muscles (integral of Poes.dt) were measured during the application of 5, 7.5, and 10 cmH2O of CPAP. Dyspnoea, gas exchange and pattern of breathing were also assessed. Inspiratory effort and the pressure-time product both for the diaphragm and the inspiratory muscles fell significantly with CPAP in a dose-dependent fashion. Both the pattern of breathing and level of dyspnoea improved with CPAP. End-expiratory lung volume remained stable at the lower levels of CPAP, with only modest increases at the higher levels. Arterial oxygen tension (Pa,O2) and arterial carbon dioxide tension (Pa,CO2) either improved or remained stable with CPAP. We conclude that the noninvasive application of CPAP to spontaneously breathing patients with severe COPD in acute respiratory failure decreases inspiratory effort and dyspnoea whilst improving breathing pattern. It is conceivable that the early institution of CPAP in this setting may obviate the need for intubation and conventional mechanical ventilation.

Pressure support reduces inspiratory effort and dyspnea during exercise in chronic airflow obstruction.

Exercise training has been of limited success in patients with severe chronic airflow obstruction (CAO), in part because of the reduced ventilatory capacity and excessive dyspnea experienced. Pressure support (PS) is a new form of mechanical ventilation which can effectively assist ventilation when applied noninvasively to patients in acute respiratory failure. It was hypothesized that PS might also be used to improve exercise performance, and ultimately physical conditioning, in ambulatory patients with CAO undergoing exercise training. To begin to address this concept, the objectives of the present study were (1) to examine the feasibility of providing PS to exercising patients with CAO and (2) to determine its effects on breathing pattern, inspiratory effort, and dyspnea. Flow and volume, mouth, esophageal, and gastric pressure were measured in seven patients with severe CAO (mean FEV1 = 0.75 +/- SEM 0.09 L) performing constant workload bicycle exercise (33 +/- 6 watts) during control conditions and with the application of PS (approximately 10 cm H2O). PS increased minute ventilation as a result of changes in both tidal volume and respiratory rate. This occurred despite marked reductions in inspiratory effort, as indicated by the pressure-time integrals of esophageal (68 +/- 5% control, p < 0.0005) and transdiaphragmatic pressure (52 +/- 8% control, p < 0.0005). Using a 5-point bidirectional scale to assess changes in dyspnea, breathlessness improved significantly with the addition of PS (2.3 +/- 0.6, p < 0.05) and worsened to a similar degree when it was removed (2.1 +/- 0.5, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of static and dynamic measurements of intrinsic PEEP in mechanically ventilated patients.

Intrinsic positive end-expiratory pressure (PEEPi) is routinely determined under static conditions by occluding the airway at end-expiration (PEEPi,stat), the resulting plateau pressure representing the average PEEPi present within a nonhomogeneous lung. In contrast, PEEPi can also be evaluated dynamically (PEEPi,dyn) by recording the change in pressure required to initiate lung inflation. It has been suggested that PEEPi,dyn reflects the lowest regional PEEPi, and therefore underestimates PEEPi,stat in the presence of heterogenous mechanical properties. The purposes of this study were (1) to compare PEEPi obtained with these two methods in mechanically ventilated patients with significant airway obstruction (AWO) and those without (non-AWO), and (2) to relate any discrepancies observed with other indices of respiratory mechanics. PEEPi,stat, PEEPi,dyn, and respiratory mechanics were measured during controlled mechanical ventilation in 22 sedated, paralyzed patients. PEEPi,dyn was significantly less than PEEPi,stat in AWO, averaging 3.0 +/- 0.5 (SEM) and 9.3 +/- 1.1 (SEM) cm H2O, respectively (p < 0.0001). In contrast, these values were more comparable in non-AWO, averaging 4.6 +/- 0.8 and 5.4 +/- 1.0 cm H2O (p > 0.05). As a result, the ratio of PEEPi,dyn to PEEPi,stat amounted to 0.36 +/- 0.06 for AWO compared with 0.87 +/- 0.05 in non-AWO (p < 0.005). Maximal (Rmax) and minimal (Rmin) respiratory resistance were greater in AWO whereas respiratory compliance (Crs) was no different between groups. PEEPi,dyn/PEEPi,stat was inversely related to delta P, the pressure losses attributable to time constant inequalities and viscoelastic tissue properties (r = 0.64, p < 0.005). No correlation was found between this ratio and Rmax, Rmin, or Crs.(ABSTRACT TRUNCATED AT 250 WORDS)

[Computer-assisted pulse wave diagnosis--use and results in early diagnosis of arteriosclerotic vascular diseases]. / Computergestützte Pulswellendiagnostik--Anwendung und Ergebnisse zur Frühdiagnostik arteriosklerotischer Gefässerkrankungen.

A method for computer-analysis of noninvasive pulse waves for diagnosis of angiologic disease is described. Quantitative analysis of pulse waves using new and significant criteria and allows early diagnosis of arteriosclerotic lesions.

[Performance of a rescue breathing device with glossopalatinal tube]. / Die Leistungsfähigkeit eines Atemspende-Hilfsmittels mit glossopalatinalem Tubus.

The "Lifeway" is a device for rescue breathing consisting of a mouthpiece for the rescuer, a non-rebreathing valve, a mouth-sealing cap and a glosso-palatinal tube (GPT) reaching into the patient's mouth. 54 patients--22 toothless and 32 with firm teeth--were ventilated mechanically via the original "Lifeway", via a variant with additional side-holes in the GPT, and, for comparison, via anaesthesia mask plus oropharyngeal airway and via endotracheal tube. Ventilation was sufficient: The arterial oxygen saturations, measured by pulse oximetry, and the end-tidal CO2 partial pressures were equal to those during ventilation via mask. Placing the modified "Lifeway" in toothless patients was significantly easier than placing the original and as easy as placing the mask; with the patients having firm teeth there were no significant differences. The incidence of obstructions, as registered by impediments to exhalation and by increases in peak inspiratory pressure, was significantly less frequent with the modified device, since the tongue could be "scooped" to a ventro-caudal direction if necessary. The modified "Lifeway" was as effective as the combination of anaesthesia mask and pharyngeal airway. The problems of the latter are, however, avoided; the use of the device by laymen thus seems feasible.

[Computer analysis of peripheral pulse curves]. / Computeranalyse peripherer Pulskurven.

The methodical fundaments as well as the technical solutions for a technique of the computerized analysis of non-invasively registered peripheral arterial pulse curves are demonstrated. Hereby a quantitative analysis of the pulse curves using new and significant evaluation parameters is performed as well as a reference to the probability diagnosis for the total estimation of the pulse curve is given. The technique is realised in form of a mobile microcomputer measuring place and allows an automatic registration, evaluation documentation and recording of rheograms and pulse oscillograms, respectively immediately at the patient's bed and is suited for a broad application in the angiological preliminary and special diagnostics.