Formación en Medicina Intensiva. Un reto a nuestro alcance / Training in Intensive Care Medicine. A challenge within reach

La formación médica se encuentra actualmente inmersa en un proceso de cambio de modelo. El nuevo paradigma pretende ser más efectivo, más integrado en el sistema sanitario y muy dirigido a la aplicación directa del conocimiento en la práctica clínica. Frente al sistema de formación actual basado en la certificación del cumplimiento de una serie de rotaciones y estancias en determinadas unidades asistenciales, el nuevo modelo propone un proceso formativo más estructurado, basado en la adquisición progresiva de competencias específicas, y en el que el residente debe jugar un papel activo en el diseño de su programa de formación. La formación basada en competencias garantiza un aprendizaje más transparente, de calidad objetiva, actualizada, homogénea y homologable internacionalmente. Los tutores juegan un papel esencial como gestores principales del proceso, es imprescindible el compromiso institucional con su labor, se les debe proporcionar tiempo y formación específica para la evaluación formativa, que es la piedra angular del nuevo modelo. Se deben incorporar nuevas formas de evaluación objetiva tanto formativa como sumativa, que garanticen que se están consiguiendo las competencias predefinidas. El movimiento libre de especialistas en Europa es un objetivo muy deseable que implica quela calidad de la formación recibida ha de ser alta y homologable en los diferentes países. El programa Competency Based Training in Intensive Care Medicine in Europe es nuestra principal fortaleza para conseguir este objetivo. Las sociedades científicas deben impulsar y facilitar todas aquellas iniciativas que mejoren la calidad asistencial y, por lo tanto, la formación del especialista. Su misión es el diseño de estrategias y procesos para favorecer la formación, la acreditación y las relaciones de asesoramiento con los gobiernos

The medical training model is currently immersed in a process of change. The new paradigm is intended to be more effective, more integrated within the healthcare system, and strongly oriented towards the direct application of knowledge to clinical practice. Compared with the established training system based on certification of the completion of a series or rotations and stays in certain healthcare units, the new model proposes a more structured training process based on the gradual acquisition of specific competences, in which residents must play an active role in designing their own training program. Training based on competences guarantees more transparent, updated and homogeneous learning of objective quality, and which can be homologated internationally. The tutors play a key role as the main directors of the process, and institutional commitment to their work is crucial. In this context, tutors should receive time and specific formation to allow the evaluation of training as the cornerstone of the new model. New forms of objective summative and training evaluation should be introduced to guarantee that the predefined competences and skills are effectively acquired. The free movement of specialists within Europe is very desirable and implies that training quality must be high and amenable to homologation among the different countries. The Competency Based training in Intensive Care Medicine in Europe program is our main reference for achieving this goal. Scientific societies in turn must impulse and facilitate all those initiatives destined to improve healthcare quality and therefore specialist training. They have the mission of designing strategies and processes that favor training, accreditation and advisory activities with the government authorities

Training in intensive care medicine. A challenge within reach.

The medical training model is currently immersed in a process of change. The new paradigm is intended to be more effective, more integrated within the healthcare system, and strongly oriented towards the direct application of knowledge to clinical practice. Compared with the established training system based on certification of the completion of a series or rotations and stays in certain healthcare units, the new model proposes a more structured training process based on the gradual acquisition of specific competences, in which residents must play an active role in designing their own training program. Training based on competences guarantees more transparent, updated and homogeneous learning of objective quality, and which can be homologated internationally. The tutors play a key role as the main directors of the process, and institutional commitment to their work is crucial. In this context, tutors should receive time and specific formation to allow the evaluation of training as the cornerstone of the new model. New forms of objective summative and training evaluation should be introduced to guarantee that the predefined competences and skills are effectively acquired. The free movement of specialists within Europe is very desirable and implies that training quality must be high and amenable to homologation among the different countries. The Competency Based training in Intensive Care Medicine in Europe program is our main reference for achieving this goal. Scientific societies in turn must impulse and facilitate all those initiatives destined to improve healthcare quality and therefore specialist training. They have the mission of designing strategies and processes that favor training, accreditation and advisory activities with the government authorities.

SwissScoring--a nationwide survey of NEMS assessing practices and its accuracy.

BACKGROUND: The nine equivalents of nursing manpower use score (NEMS) is used to evaluate critical care nursing workload and occasionally to define hospital reimbursements. Little is known about the caregivers' accuracy in scoring, about factors affecting this accuracy and how validity of scoring is assured. METHODS: Accuracy in NEMS scoring of Swiss critical care nurses was assessed using case vignettes. An online survey was performed to assess training and quality control of NEMS scoring and to collect structural and organizational data of participating intensive care units (ICUs). Aggregated structural and procedural data of the Swiss ICU Minimal Data Set were used for matching. RESULTS: Nursing staff from 64 (82%) of the 78 certified adult ICUs participated in this survey. Training and quality control of scoring shows large variability between ICUs. A total of 1378 nurses scored one out of 20 case vignettes: accuracy ranged from 63.7% (intravenous medications) to 99.1% (basic monitoring). Erroneous scoring (8.7% of all items) was more frequent than omitted scoring (3.2%). Mean NEMS per case was 28.0 ± 11.8 points (reference score: 25.7 ± 14.2 points). Mean bias was 2.8 points (95% confidence interval: 1.0-4.7); scores below 37.1 points were generally overestimated. Data from units with a greater nursing management staff showed a higher bias. CONCLUSION: Overall, nurses assess the NEMS score within a clinically acceptable range. Lower scores are generally overestimated. Inaccurate assessment was associated with a greater size of the nursing management staff. Swiss head nurses consider themselves motivated to assure appropriate scoring and its validation.

Patient satisfaction with care in the intensive care unit: can we rely on proxies?

BACKGROUND: To investigate whether next of kin can be addressed as proxy to assess patients' satisfaction with care in the intensive care unit (ICU). METHODS: Prospective observational multicentre study. Two hundred and thirty-five patients with an ICU length of stay of ≥2 days and 266 of their adult next of kin participated. Patient satisfaction was assessed by a questionnaire, distributed upon discharge from an ICU and compared with next of kin's answers. The possible range of answers was 0-100, with higher numbers indicating higher satisfaction. The main outcome measure was the extent of agreement between patients' satisfaction with care and the ratings of their next of kin. RESULTS: Patients were most satisfied concerning physicians' competence (86.7±16.3), while least satisfaction was observed for the management of agitation and restlessness (78.2±23.5). There was no significant difference between next of kin's and patients' ratings. Agreement between patients and proxies was the highest concerning overall satisfaction (Cohen's κ 0.40) and the lowest for coordination of care (0.24). Spouses/partners had a higher agreement with the patients' ratings than other proxies. CONCLUSIONS: If the patient is unable to rate his satisfaction with care in the ICU, next of kin may be taken as an appropriate surrogate. TRIAL REGISTRATION: The study has been registered at ClinicalTrials.gov, Reg No: NTC 00890513.

Does ICU length of stay influence quality of life?

BACKGROUND: Patients with prolonged stay in the intensive care unit (ICU) use a disproportionate share of resources. However, it is not known if such treatment results in impaired quality of life (QOL) as compared to patients with a short length of stay (LOS) when taking into account the initial severity of illness. METHODS: Prospective, observational case-control study in a university hospital surgical and trauma adult ICU. All patients admitted to the ICU during a 1-year period were included. Patients with a cumulative LOS in the ICU > 7 days, surviving up to 1 year after ICU admission and consenting were identified (group L, n = 75) and matched to individuals with a shorter stay (group S). Matching criteria were diagnostic group and severity of illness. Health-related quality of life (HRQOL) was assessed 1 year after admission using the short-form 36 (SF-36) and was compared between groups and to the general population. Further, overall QOL was estimated using a visual analogue scale (VAS) and willingness to consent to future intensive care, and was compared between groups L and S. RESULTS: Based on ANCOVA, a significant difference between groups L and S was noted for two out of eight scales: role physical (P = 0.033) and vitality (P = 0.041). No differences were found for the physical component summary (P = 0.065), the mental component summary (P = 0.267) or the VAS (P = 0.316). Further, there was no difference in expectation to consent to future intensive care (P = 0.149). As compared to the general population, we found similar scores for the mental component summary and for three of eight scales in group L and five of eight scales in group S. CONCLUSIONS: When taking into account severity of illness, HRQOL 1 year after intensive care is comparable between patients with a short and a long LOS in the ICU. Thus, prolonged stay in the ICU per se must not be taken as an indicator of future poorer HRQOL. However, as compared to the general population, significant differences, mostly in physical aspects of QOL, were found for both groups of patients.

Effects of cerebral perfusion pressure and increased fraction of inspired oxygen on brain tissue oxygen, lactate and glucose in patients with severe head injury.

OBJECTIVE: The purpose of the study was to measure the effects of increased inspired oxygen on patients suffering severe head injury and consequent influences on the correlations between CPP and brain tissue oxygen (PtiO2) and the effects on brain microdialysate glucose and lactate. METHODS: In a prospective, observational study 20 patients suffering severe head injury (GCS< or =8) were studied between January 2000 and December 2001. Each patient received an intraparenchymal ICP device and an oxygen sensor and, in 17 patients brain microdialysis was performed at the cortical-subcortical junction. A 6 h 100% oxygen challenge (F IO2 1.0) ( Period A) was performed as early as possible in the first 24 hours after injury and compared with a similar 6 hour period following the challenge ( Period B). Statistics were performed using the linear correlation analysis, one sample t-test, as well as the Lorentzian peak correlation analysis. RESULTS: F IO2 was positively correlated with PtiO2 (p < 0.0001) over the whole study period. PtiO2 was significantly higher (p < 0.001) during Period A compared to Period B. CPP was positively correlated with PtiO2 (p < 0.001) during the whole study. PtiO2 peaked at a CPP value of 78 mmHg performing a Lorentzian peak correlation analysis of all patients over the whole study. During Period A the brain microdialysate lactate was significantly lower (p = 0.015) compared with Period B. However the brain microdialysate glucose remained unchanged. CONCLUSION: PtiO2 is significantly positively correlated with F IO2, meaning that PtiO2 can be improved by the simple manipulation of increasing F IO2 and ABGAO2. PtiO2 is positively correlated with CPP, peaking at a CPP value of 78 mmHg. Brain microdialysate lactate can be lowered by increasing PtiO2 values, as observed during the oxygen challenge, whereas microdialysate glucose is unchanged during this procedure. Extension of the oxygen challenge time and measurement of the intermediate energy metabolite pyruvate may clarify the metabolic effects of the intervention. Prospective comparative studies, including analysis of outcome on a larger multicenter basis, are necessary to assess the long term clinical benefits of this procedure.

Resource use in the ICU: short- vs. long-term patients.

BACKGROUND: Intensive care medicine uses a disproportionate share of medical resources, and little is known about the distribution of resources between different patient groups. METHODS: In this prospective observational study, all patients admitted between 1 January 1998 and 31 December 1999 to our medical-surgical university's ICU were assigned to one of two groups according to length of stay (LOS): patients staying more than 7 days in the unit (group L) and those staying a maximum of 7 days (group S). Resource use was estimated using TISS-28, number of nursing shifts, use of mechanical ventilation, and use of renal replacement therapy. Further, SAPS II and ICU and hospital mortalities were recorded. RESULTS: Of 5481 patients, 583 (10.6%) were in group L and 4898 in group S (89.4%). Patients in group L were more severely sick upon admission than those in group S. Patients in group L stayed a total of 9726 days in the ICU (52.5% of the total LOS). In group L, 69.2% of all shifts with respiratory support and 80.1% of all shifts with renal replacement were used. Further, group L patients consumed 53.4% (909225) of all TISS points provided. The ICU-mortality rates were 14.4% in group L and 7.2% in group S, and the hospital mortality rates were 19.9% and 9.8%, respectively. A mean of 1898 TISS points was used per patient surviving the hospital stay in group L compared with 190 points in group S. CONCLUSIONS: In this university-based, medical-surgical adult ICU, 11% of all patients stayed more than 7 days in the unit and consumed more than 50% of all resources. Thus, a highly disproportionate amount of resources were used per survivor in group L compared with those in group S.

Atelectasis formation during anesthesia: causes and measures to prevent it.

Pulmonary gas exchange is regularly impaired during general anaesthesia with mechanical ventilation. This results in decreased oxygenation of blood. A major cause is collapse of lung tissue (atelectasis), which can be demonstrated by computed tomography but not by conventional chest x-ray. Collapsed lung tissue is present in 90% of all subjects, both during spontaneous breathing and after muscle paralysis, and whether intravenous or inhalational anaesthetics are used. There is a correlation between the amount of atelectasis and pulmonary shunt. Shunt does not increase with age. In obese patients, larger atelectatic areas are present than in lean ones. Finally, patients with chronic obstructive lung disease may show less or even no atelectasis. There are different procedures that can be used in order to prevent atelectasis or to reopen collapsed lung tissue. The application of positive end-expiratory pressure (PEEP) has been tested in several studies. On the average, arterial oxygenation does not improve markedly, and atelectasis may persist. Further, reopened lung units re-collapse rapidly after discontinuation of PEEP. Inflation of the lungs to an airway pressure of 40 cm H2O, maintained for 7-8 seconds (recruitment or "vital capacity" manoeuvre), re-expands all previously collapsed lung tissue. During induction of anaesthesia, the use of a gas mixture, that includes a poorly absorbed gas such as nitrogen, may prevent the early formation of atelectasis. During ongoing anaesthesia, pulmonary collapse reappears slowly if a low fraction of oxygen in nitrogen is used for the ventilation of the lungs after a previous VC-manoeuvre. On the other hand, ventilation of the lungs with pure oxygen results in a rapid reappearance of atelectasis. Thus, ventilation during anaesthesia should be done if possible with a moderate fraction of inspired oxygen (FIO2, e.g. 0.3-0.4). Alternatively, if the lungs are ventilated with a high inspiratory fraction of oxygen, the use of PEEP may be considered. In summary, atelectasis is present in most humans during anaesthesia and is a major cause of impaired oxygenation. Avoiding high fractions of oxygen in inspired gas during induction and maintenance of anaesthesia may prevent formation of atelectasis. Finally, intermittent "vital capacity"-manoeuvres together with PEEP reduces the amount of atelectasis and pulmonary shunt.

Dynamics of re-expansion of atelectasis during general anaesthesia.

A major cause of impaired gas exchange during general anaesthesia is atelectasis, causing pulmonary shunt. A 'vital capacity' (VC) manoeuvre (i.e. inflation of the lungs up to 40 cm H2O, maintained for 15 s) may re-expand atelectasis and improve oxygenation. However, such a manoeuvre may cause adverse cardiovascular effects. Reducing the time of maximal inflation may improve the margin of safety. The aim of this study was to analyse the change over time in the amount of atelectasis during a VC manoeuvre in 12 anaesthetized adults with healthy lungs. I.v. anaesthesia with controlled mechanical ventilation (VT 9 (SD 1) ml kg-1) was used. For the VC manoeuvre, the lungs were inflated up to an airway pressure (Paw) of 40 cm H2O. This pressure was maintained for 26 s. Atelectasis was assessed by analysis of computed x-ray tomography. The amount of atelectasis, measured at the base of the lungs, was 4.0 (SD 2.7) cm2 after induction of anaesthesia. The decrease in the amount of atelectasis over time during the VC manoeuvre was described by a negative exponential function with a time constant of 2.6 s. At an inspired oxygen concentration of 40%, PaO2 increased from 17.2 (4.0) kPa before to 22.2 (6.0) kPa (P = 0.013) after the VC manoeuvre. Thus in anaesthetized adults undergoing mechanical ventilation with healthy lungs, inflation of the lungs to a Paw of 40 cm H2O, maintained for 7-8 s only, may re-expand all previously collapsed lung tissue, as detected by lung computed tomography, and improve oxygenation. We conclude that the previously proposed time for a VC manoeuvre may be halved in such subjects.

Validation of "nine equivalents of nursing manpower use score" on an independent data sample.

OBJECTIVE: To compare the recently developed "nine equivalents of nursing manpower use score" (NEMS) with the simplified Therapeutic Intervention Scoring System (TISS-28). DESIGN: Prospective single centre study. SETTING: Adult 30-bed medical-surgical intensive care unit (ICU) in a tertiary care university hospital. PATIENTS: Data from all patients admitted in 1997 to the ICU were included in the study. METHODS AND RESULTS: NEMS and TISS-28 items were recorded prospectively for each nursing shift. There were three shifts per day. The Simplified Acute Physiology Score (SAPS) II was calculated for the first 24 h of ICU stay and each patient's basic demographic data were collected. The agreement between NEMS and TISS-28 was assessed by calculating the mean difference and the standard deviation of the differences between the two measures. Further, regression techniques and Pearson's correlation were used. Altogether, 2743 patients with a total of 28,220 nursing shifts were included; 62% of the shifts were used for postoperative/trauma patients and 38% for medical patients. Mean NEMS was 26.0 +/- 8.1 and mean TISS-28 was 26.5 +/- 7.9. The scores differed by < or = 3 points in 49 % of all shifts. The bias was -0.5 +/- 5.3 (95% confidence interval -0.47 to -0.60) and the limits of agreement were -11.1 to +10.1. The relation between the two systems was NEMS = 4.7 +/- 0.8 x TISS-28 (r = 0.78, r2 = 0.62, p < 0.001). Including postoperative/trauma patients only: NEMS = 1.9 +/- 0.9 x TISS-28, for medical patients this equation was: NEMS = 6.0 + 0.8 x TISS-28. First-day SAPS II explained 11% of the variability in first-shift NEMS and 5% of the variability in first-shift TISS-28. CONCLUSIONS: This study confirms a good agreement between TISS-28 and NEMS in a large, independent sample. However, as shown by the differences between medical and postoperative/trauma patients, a change in case mix may result in different regression equations. Further, wide limits of agreement indicate that there may be a rather large variability between the two measures at the individual level.

Positive end-expiratory pressure prevents atelectasis during general anaesthesia even in the presence of a high inspired oxygen concentration.

BACKGROUND: General anaesthesia impairs the gas exchange in the lungs, and moderate desaturation (SaO2 86-90%) occurred in 50% of anaesthetised patients in a blinded pulse oximetry study. A high FiO2 might reduce the risk of hypoxaemia, but can also promote atelectasis. We hypothesised that a moderate positive end-expiratory pressure (PEEP) level of 10 cmH2O can prevent atelectasis during ventilation with an FiO2 = 1.0. METHODS: Atelectasis was evaluated by computed tomography (CT) in 13 ASA I-II patients undergoing elective surgery. CT scans were obtained before and 15 min after induction of anaesthesia. Then, recruitment of collapsed lung tissue was performed as a "vital capacity manoeuvre" (VCM, inspiration with Paw = 40 cmH2O for 15 s), and a CT scan was obtained at the end of the VCM. Thereafter, PEEP = 0 cmH2O was applied in group 1, and PEEP = 10 cmH2O in group 2. Additional CT scans were obtained after the VCM. Oxygenation was measured before and after the VCM. RESULTS: Atelectasis (> 1 cm2) was present in 12 of the 13 patients after induction of anaesthesia. At 5 and 10 min after the VCM, atelectasis was significantly smaller in group 2 than group 1 (P < 0.005). A significant inverse correlation was found between PaO2 and atelectasis. CONCLUSIONS: PEEP = 10 cmH2O reduced atelectasis formation after a VCM, when FiO2 = 1.0 was used. Thus, a VCM followed by PEEP = 10 cmH2O should be considered when patients are ventilated with a high FiO2 and gas exchange is impaired.

Airway closure, atelectasis and gas exchange during general anaesthesia.

Airway closure and the formation of atelectasis have been proposed as important contributors to impairment of gas exchange during general anaesthesia. We have elucidated the relationships between each of these two mechanisms and gas exchange. We studied 35 adults with healthy lungs, undergoing elective surgery. Airway closure was measured using the foreign gas bolus technique, atelectasis was estimated by analysis of computed x-ray tomography, and ventilation-perfusion distribution (VA/Q) was assessed by the multiple inert gas elimination technique. The difference between closing volume and expiratory reserve volume (CV-ERV) increased from the awake to the anaesthetized state. Linear correlations were found between atelectasis and shunt (r = 0.68, P < 0.001), and between CV-ERV and the amount of perfusion to poorly ventilated lung units ("low Va/Q", r = 0.57, P = 0.001). Taken together, the amount of atelectasis and airway closure may explain 75% of the deterioration in PaO2. There was no significant correlation between CV-ERV and atelectasis. We conclude that in anaesthetized adults with healthy lungs, undergoing mechanical ventilation, both airway closure and atelectasis contributed to impairment of gas exchange. Atelectasis and airway closure do not seem to be closely related.

Intensive care 1980-1995: change in patient characteristics, nursing workload and outcome.

OBJECTIVE: To assess temporal changes in patient characteristics, nursing workload and outcome of the patients and to compare the actual amount of available nursing staff with the estimated needs in a medical-surgical ICU. DESIGN: Retrospective analysis of prospectively collected data. SETTING: A medical-surgical adult intensive care unit (ICU) in a Swiss university hospital. PATIENTS: Data of all patients staying in the ICU between January 1980 and December 1995 were included. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: The estimated number of nurses needed was defined according to the Swiss Society of Intensive Care Medicine (SGI) grading system: category I = one nurse/patient/shift (= 8 h), category II = one nurse/two patients/shift, category III = one nurse/three patients/shift. An intervention score (IS) was obtained, based on a number of specific activities in the ICU. There was a total of 35,327 patients (32% medical and 68% postoperative/trauma patients). Over time, the number of patients per year increased (1980/1995: 1,825/2,305, p < 0.001) and the length of ICU stay (LOS) decreased (4.1/3.8 days, p < 0.013). There was an increase in the number of patients aged > 70 years (19%/28%, p < 0.001), and a decrease in the number of patients < 60 years (58%/41%, p < 0.001). During the same time period, the IS increased two-fold. Measurement of nursing workload showed an increase over time. The number of nursing days per year increased (1980/1995: 7454/8681, p < 0.019), as did the relative amount of patients in category I (49%/71%, p < 0.001), whereas the portion of patients in category II (41%/28%, p < 0.019) and category III (10%/0%) decreased. During the same time period, mortality at ICU discharge decreased (9.0%/7.0%, p < 0.002). CONCLUSIONS: During the last 16 years, there has been a marked increase in workload at this medical-surgical ICU. Despite an increase in the number of severely sick patients (as defined by the nursing grading system) and patient age, ICU mortality and LOS declined from 1980 to 1995. This may be ascribed to improved patient treatment or care. Whether an increasingly liberal discharge policy (transfer to newly opened intermediate care units, transfer of patients expected to die to the ward) or a more rigorous triage (denying admission to patients with a very poor prognosis) are confounding factors cannot be answered by this investigation. The present data provide support for the tenet that there is a trend toward more complex therapies in increasingly older patients in tertiary care ICUs. Calculations for the number or nurses needed in an ICU should take into acount the increased turnover of patients and the changing patient characteristics.

Volumetric analysis of aeration in the lungs during general anaesthesia.

Spiral computed tomography (CT) allows volumetric analysis of formation of atelectasis and aeration of the lungs during anaesthesia. We studied 26 premedicated patients undergoing elective surgery allocated to group 1 (conscious, spontaneous breathing, investigating inspiration and expiration), group 2 (general anaesthesia with mechanical ventilation, investigating inspiration and expiration) or group 3 (general anaesthesia with mechanical ventilation, investigating changes over time). Using spiral CT, the lungs were studied either before or during general anaesthesia. CT scans were grouped into the following areas: overaeration, normal aeration, reduced aeration, poor aeration and atelectasis. The mechanism of atelectasis appeared to be both gravitational forces and a diaphragm-related force that acts regionally in caudal lung regions. Mean atelectasis formation and poorly aerated regions comprised approximately 4% of the total lung volume between the diaphragm and carina, giving a mean value of 16-20% of the normal aerated lung tissue being either collapsed or poorly aerated. The vertical ventilation distribution was more even during anaesthesia than in the awake state.

Atelectasis and pulmonary shunting during induction of general anaesthesia--can they be avoided?

BACKGROUND: Gas exchange is regularly impaired during general anaesthesia with mechanical ventilation. A major cause of this disorder appears to be atelectasis and consequently pulmonary shunt. After re-expansion, atelectasis reappears very slowly if 30% oxygen in nitrogen is used, but much faster if 100% oxygen is used. The aim of the present study-was to evaluate if early formation of atelectasis and pulmonary shunt may be avoided if the lungs are ventilated with 30% oxygen in nitrogen instead of 100% oxygen during the induction of general anaesthesia. METHODS: Twenty-four adult patients with healthy lungs scheduled for elective surgery were investigated. During induction of anaesthesia, the lungs were manually ventilated via a face mask, using either 30% oxygen in nitrogen (group 1, n = 12) or 100% oxygen (group 2, n = 12). Atelectasis was estimated by computed x-ray tomography and ventilation-perfusion distribution with the multiple inert gas elimination technique, both awake and during general anaesthesia with mechanical ventilation. RESULTS: No atelectasis was present in the awake subjects. After induction of anaesthesia, the mean amount of atelectasis was minor (0.2 +/- 0.4 cm2) in group 1 and considerably greater (8.0 +/- 8.2 cm2) in group 2 (P < 0.001). The pulmonary shunt was 0.3 +/- 0.7% of cardiac output in the awake subjects. This value increased to 2.1 +/- 3.8% in group 1 and to 6.5 +/- 5.2% in group 2 (P < 0.05). The indices of VA/Q mismatch showed no difference between the two groups. CONCLUSION: During induction of general intravenous anaesthesia in patients with healthy lungs, gas composition plays an important role for atelectasis formation and the establishment of pulmonary shunt. By using a mixture containing 30% oxygen in nitrogen, the early formation of atelectasis and pulmonary shunt may, at least in part, be avoided.

[Necrotizing fasciitis of soft tissues of the face and neck]. / Nekrotisierende Fasziitis der Gesichts- und Halsweichteile.

Three cases of cervical necrotizing fasciitis are presented. One case was odontogenic in origin and two were due to pharyngeal infectious. Bacteria cultured represented multiple bacterial species. Airway control was necessary early, as was wide surgical exploration of the fascial spaces of the neck with re-exploration as necessary. Intensive medical support was crucial to prevent or treat complications. Cervical necrotizing fasciitis has an overall mortality rate of 30 per cent at the University of Bern.