Effects of noninvasive positive pressure ventilatory support in non-COPD patients with acute respiratory insufficiency after early extubation

OBJECTIVE

To investigate the effects of noninvasive positive pressure ventilation (NPPV) on pulmonary gas exchange, breathing pattern, intrapulmonary shunt fraction, oxygen consumption, and resting energy expenditure in patients with persistent acute respiratory failure but without chronic obstructive pulmonary disease (COPD) after early extubation.

DESIGN

Prospective study.

SETTING

Multidisciplinary intensive care unit of a university hospital.

PATIENTS

15 patients after prolonged mechanical ventilation (> 72 h) with acute respiratory insufficiency after early extubation.

INTERVENTIONS

Criteria for early extubation were arterial oxygen tension (PaO2) > or = 40 mm Hg (fractional inspired oxygen 0.21), arterial carbon dioxide tension (PaCO2) < or = 55 mm Hg, pH > 7.32, respiratory rate < or = 40 breaths per min, tidal volume (VT) > or = 3 ml/kg, rapid shallow breathing index < or = 190 and negative inspiratory force > or = 20 cmH2O. After extubation, two modes of NPPV were applied [continuous positive airway pressure (CPAP) of 5 cmH2O and pressure support ventilation (PSV) with 15 cmH2O pressure support].

MEASUREMENTS AND MAIN RESULTS

Oxygenation and ventilatory parameters improved during both modes of NPPV (p < 0.05): increase in PaO2 of 11 mm Hg during CPAP and 21 mm Hg during PSV; decrease in intrapulmonary shunt fraction of 7% during CPAP and 12% during PSV; increase in tidal volume of 1 ml/kg during CPAP and 4 ml/kg during PSV; decrease in respiratory rate 6 breaths/min during CPAP and 9 breaths/min during PSV. Oxygen consumption (15% during CPAP, 22% during PSV) and resting energy expenditure (12% during CPAP, 20% during PSV) were reduced (p < 0.05). PaCO2 decreased, whereas minute ventilation and pH increased during PSV (p < 0.05). The median duration of NPPV was 2 days. Two patients had to be reintubated.

CONCLUSIONS

In non-COPD patients with persistent acute respiratory failure after early extubation, NPPV improved pulmonary gas exchange and breathing pattern, decreased intrapulmonary shunt fraction, and reduced the work of breathing.

Response to inhaled nitric oxide (NO) is not associated with changes of plasma cGMP levels in patients with acute lung injury

BACKGROUND

A clinically relevant increase of PaO subset2 or decrease of pulmonary vascular resistance (PVR) upon inhalation of NO (iNO) does occur in only 60 to 80% of patients with acute lung injury. The mechanisms for divergent responses of different patients have not yet been fully elucidated. Since NO mediates its pulmonary effects by stimulating soluble guanylate cyclase, thereby increasing levels of cyclic guanosinemonophosphate (cGMP), we hypothesized that pulmonary cGMP production upon iNO might be suppressed in patients not responding to iNO treatment.

METHODS

After approval by the local ethical committee and after informed consent had been obtained, both arterial and mixed-venous cGMP levels were analyzed in 13 patients in whom iNO was administered to treat pulmonary hypertension and/or hypoxemia due to acute respiratory distress syndrome (n = 11) or reperfusion injury following lung transplantation (n = 2). Both cardiorespiratory variables and cGMP concentrations were documented simultaneously at baseline, 15 min after inhalation of 8 ppm of NO, and 15 min after withdrawal of NO, respectively.

RESULTS

Inhaled NO resulted in a significant increase in PaO(2)/FiO(2) and a decrease in PVR. Arterial and mixed venous concentration of cGMP (median) also increased significantly upon iNO from 2.5 to 6.5 nM (p <0.05) and from 3.0 to 5.7 nM (p <0.05), respectively. Theses effects were fully reversible after withdrawal of iNO. No gradients between arterial and mixed venous cGMP concentrations were detected (p = 0.12). Regression analysis showed no relationship between baseline arterial cGMP concentrations and changes of either PaO(2)/FiO(2) (p = 0. 62) or PVR (p = 0.91). Similarly, no relationship was found between the rise of arterial cGMP concentration subsequent to iNO and corresponding changes of PaO(2) (p = 0.40) or PVR (p = 0.74), respectively.

CONCLUSION

Inhalation of NO significantly stimulates soluble guanylate cyclase within the lungs in patients with acute lung injury. However, neither baseline cGMP nor its rise during treatment with inhaled NO can predict the clinical efficacy of iNO in humans. Furthermore, the fact that increased cGMP concentrations were detected during administration of iNO in mixed venous blood (i.e. pulmonary inflow) strongly suggest that the pharmacological effects of iNO are not fully selective for the lungs, but may also affect extrapulmonary organs.

Extraction and isolation of linear alkylbenzenesulfonate and its sulfophenylcarboxylic acid metabolites from fish samples

Linear alkylbenzenesulfonate (LAS) is the most widely used synthetic surfactant. In fish, assessment of the environmental risk and investigation of the biotransformation behavior of LAS require compound-specific methods for extraction and isolation of LAS and its biotransformation products, sulfophenylcarboxylic acids (SPC). Matrix solid-phase dispersion (MSPD) extraction with subsequent ion-pair liquid-liquid (IP-LL) partitioning of the extract was a time-efficient sample preparation method for analysis of LAS. The recovery of parent LAS from spiked fish exceeded 70%, and the limit of quantitation ranged around 0.2 mg.kg-1 corresponding to 0.6 mumol.kg-1. In a simultaneous determination of LAS and SPC in fish, the analytes were MSPD extracted in different fractions. The target compounds were separated from the sample matrix by protein precipitation and subsequent isolation of (a) SPC by graphitized carbon black solid-phase extraction of the supernatant and (b) parent LAS by IP-LL partitioning of the pellet obtained after protein precipitation. The recoveries of the model compounds C12-2-LAS and C4-3-SPC were 84 +/- 6 and 65 +/- 11%, respectively. The use of C3-3-SPC as an internal standard corrected for the loss of the biotransformation product during sample workup. The suitability of both methods was demonstrated by analyzing fish containing LAS and SPC incurred during aqueous exposure.

Sensitivity and specificity of a screening test to document traumatic experiences and to diagnose post-traumatic stress disorder in ARDS patients after intensive care treatment

OBJECTIVE

Many survivors of critical illness and intensive care unit (ICU) treatment have traumatic memories such as nightmares, panic or pain which can be associated with the development of posttraumatic stress disorder (PTSD). In order to simplify the rapid and early detection of PTSD in such patients, we modified an existing questionnaire for diagnosis of PTSD and validated the instrument in a cohort of ARDS patients after long-term ICU therapy.

DESIGN

Follow-up cohort study.

SETTING

The 20-bed ICU of a university teaching hospital.

PATIENTS

A cohort of 52 long-term survivors of the acute respiratory distress syndrome (ARDS).

INTERVENTIONS AND MEASUREMENTS

The questionnaire was administered to the study cohort at two time points 2 years apart. At the second evaluation, the patients underwent a structured interview with two trained psychiatrists to diagnose PTSD according to Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) criteria. The reliability and validity of the questionnaire was then estimated and its specificity, sensitivity and optimal decision threshold determined using receiver operating characteristic (ROC) curve analyses.

RESULTS

The questionnaire showed a high internal consistency (Crohnbach's alpha = 0.93) and a high test-retest reliability (intraclass correlation coefficient alpha = 0.89). There was evidence of construct validity by a linear relationship between scores and the number of traumatic memories from the ICU the patients described (Spearman's rho = 0.48, p < 0.01). Criterion validity was demonstrated by ROC curve analyses resulting in a sensitivity of 77.0% and a specificity of 97.5% for the diagnosis of PTSD.

CONCLUSIONS

The questionnaire was found to be a responsive, valid and reliable instrument to screen survivors of intensive care for PTSD.

Stress doses of hydrocortisone reverse hyperdynamic septic shock: a prospective, randomized, double-blind, single-center study

OBJECTIVE

To investigate the effects of stress doses of hydrocortisone on the duration of vasopressor therapy in human septic shock.

DESIGN

Prospective, randomized, double-blind, single-center study.

SETTING

Twenty-bed multidisciplinary intensive care unit in a 1400-bed university hospital.

PATIENTS

Forty consecutive patients who met the ACCP/SCCM criteria for septic shock. An additional criterion for inclusion in the study was vasopressor support and high-output circulatory failure with a cardiac index of >4 L/min/m2 after fluid resuscitation (pulmonary capillary wedge pressure: 12-15 mm Hg) and without the use of positive inotropes such as dobutamine or dopexamine. The primary study end point was the time to cessation of vasopressor support (norepinephrine or epinephrine in any dose, dopamine > or = 6 microg/kg/min). Secondary study end points were the evolution of hemodynamics and the multiple organ dysfunction syndrome (MODS). The severity of illness at recruitment was graded using the Acute Physiology and Chronic Health Evaluation II and the Simplified Acute Physiology Score II scoring systems. MODS was described by the Sepsis-related Organ Failure Assessment score.

INTERVENTIONS

All eligible patients were prospectively randomized to receive either stress doses of hydrocortisone or placebo. Hydrocortisone was started with a loading dose of 100 mg given within 30 mins and followed by a continuous infusion of 0.18 mg/ kg/hr. When septic shock had been reversed, the dose of hydrocortisone was reduced to 0.08 mg/kg/hr. This dose was kept constant for 6 days. As soon as the underlying infection had been treated successfully or sodium serum concentrations had increased to >155 mmol/L, the hydrocortisone infusion was tapered in steps of 24 mg/day. Physiologic saline solution was the placebo.

MEASUREMENTS AND MAIN RESULTS

Hemodynamic and oxygen-derived variables were measured at previously defined time points over a study period of 5 days. Relevant clinical and laboratory measurements were registered for a study period of 14 days to assess the evolution of organ dysfunction. Baseline data at recruitment did not differ between the two groups. Shock reversal was achieved in 18 of the 20 patients treated with hydrocortisone vs. 16 of the 20 patients treated with placebo. Hydrocortisone significantly reduced the time to cessation of vasopressor support. The median time of vasopressor support was 2 days (1st and 3rd Quartiles, 1 and 6 days) in the hydrocortisone-treated group and 7 days (1st and 3rd Quartiles, 3 and 19 days) in the placebo group (p = .005 Breslow test). There was a trend to earlier resolution of the organ dysfunction syndrome in the hydrocortisone group.

CONCLUSIONS

Infusion of stress doses of hydrocortisone reduced the time to cessation of vasopressor therapy in human septic shock. This was associated with a trend to earlier resolution of sepsis-induced organ dysfunctions. Overall shock reversal and mortality were not significantly different between the groups in this low-sized single-center study.

Evaluation of a new continuous thermodilution cardiac output monitor in cardiac surgical patients: a prospective criterion standard study

OBJECTIVE

To evaluate the accuracy of a new continuous cardiac output monitor in critically ill patients.

DESIGN

Criterion standard study.

SETTING

Cardiac surgery intensive care unit in a university hospital.

PATIENTS

Twenty cardiac surgical patients requiring intensive care treatment with pulmonary artery catheters after surgery.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Cardiac output was monitored continuously with a modified pulmonary artery catheter that has a heating filament on the outside of the catheter. Four modes of data processing with different response times ("Normal," "Fast," "FastFilter," and "Urgent" modes) used by the monitoring system. A total of 240 determinations of cardiac output were performed using conventional bolus thermodilution technique; these results were compared with those obtained using three of the four continuous measuring modes available ("Normal," "FastFilter," and "Urgent"). Cardiac output ranged from 3.47 to 15.77 L/min (bolus thermodilution). The mean (bias) +/- SD of differences (precision) for all measurements was 0.40+/-1.26 L/min in the Normal mode (cardiac output <10 L/min: 0.34+/-0.66 L/min), 0.53+/-1.27 L/min in the FastFilter-mode (cardiac output <10 L/min: 0.60+/-0.75 L/min), and 0.63+/-1.34 L/min in the Urgent mode (cardiac output <10 L/min: 0.57+/-0.82 L/min).

CONCLUSIONS

Continuous cardiac output measurement using the thermodilution technique is reasonably accurate, reliable, and applicable in routine clinical practice. The values obtained using the Normal mode of the monitor agreed significantly better with the conventional thermodilution method than the results of the two other modes studied (FastFilter and Urgent). In addition, measurements in two patients with cardiac output values of >10 L/min did not agree with the results of the bolus thermodilution method.

First clinical implications of perioperative red cell volume measurement with a nonradioactive marker (sodium fluorescein)

We measured red cell volume (RCV) with the nonradioactive marker sodium fluorescein (SoF) in 30 patients undergoing gynecological operations. Sixteen patients underwent preoperative isovolemic hemodilution (PIHD). RCV measurements were performed before and after PIHD and at the end of the operation. All RCVs were related to corresponding hematocrit (hct) levels. We report a simplified method for its clinical application by reducing the number of blood samples required. To validate our method, we compared RCV within the PIHD bags (bag RCV) with the difference of the patients' RCV before and after PIHD. Bag RCV obtained during PIHD (mean 399+/-81 mL) was measured with a precision of 4.2% by using SoF. There was a significant difference (mean 286+/-401 mL; P < 0.05) between intraoperatively estimated and measured blood loss. The blood loss tended to be underestimated and, in some cases, was underestimated or overestimated substantially. Preoperative and postoperative hct values only offered an imprecise estimation of the patients' RCV. We conclude that RCV measurement using SoF is a precise method for monitoring changes in RCV during PIHD and surgical operation.

IMPLICATIONS

We measured red cell volume changes of 30 patients with the nonradioactive marker sodium fluorescein before and after hemodilution and postoperatively with a high precision. We frequently found large differences between intraoperatively estimated and measured blood loss. Preoperative hematocrit values offered an imprecise estimation of the patients' red cell volume.

[Retrospective analysis of transpulmonary and pulmonary arterial measurement of cardiac output in ARDS patients]

OBJECTIVES

To investigate the agreement (and its potential dependency on extra-vascular lung water) between transpulmonary (TPID) and standard pulmonary artery (PAID) thermodilution cardiac output measurements.

METHODS

One hundred and sixty simultaneous cardiac output measurements using transpulmonary and pulmonary artery thermodilution techniques were retrospectively compared in 18 patients with acute respiratory distress syndrome. In addition, extravascular lung water was determined using a double indicator technique (temperature and indocyanine green).

RESULTS

Mean (+/- SD) difference ("bias") was 0.03 L/min (+/- 1.04 L/min), linear regression analysis resulted in TPID = 0.87 PAID + 1.16 (r = 0.91). Mean extra vascular lung water was 1625 mL (minimum-maximum: 403-3266 mL) and therefore markedly elevated as could have been expected in patients with ARDS. Bias (PAID-TPID) was not dependent on extravascular lung water.

CONCLUSIONS

Transpulmonary and pulmonary artery thermodilution methods can be used interchangeably. The results demonstrate for the first time in humans that transpulmonary thermodilution provides valid cardiac output values in patients with markedly increased fluid content of the lungs.

Inhaled nitric oxide (NO) for the treatment of early allograft failure after lung transplantation. Munich Lung Transplant Group

OBJECTIVE

Inhalation of high concentrations of nitric oxide (NO) has been shown to improve gas exchange and to reduce pulmonary vascular resistance in individuals with ischemia-reperfusion injury following orthotopic lung transplantation. We assessed the cardiopulmonary effects of low doses of NO in early allograft dysfunction following lung transplantation.

DESIGN

Prospective clinical dose-response study.

SETTING

Anesthesiological intensive care unit of a university hospital.

PATIENTS AND PARTICIPANTS

8 patients following a single or double lung transplantation who had a mean pulmonary arterial pressure (PAP) in excess of 4.7 kPa (35 mmHg) or an arterial oxygen tension/fractional inspired oxygen ratio (PaO2/FIO2) of less than 13.3 kPa (100 mmHg).

INTERVENTIONS

Gaseous NO was inhaled in increasing concentrations (1, 4 and 8 parts per million, each for 15 min) via a Siemens Servo 300 ventilator.

MEASUREMENTS AND RESULTS

Cardiorespiratory parameters were assessed at baseline, after each concentration of NO, and 15 min after withdrawal of the agent [statistics: median (25th/75th percentiles: Q1/Q3), rANOVA, Dunnett's test, p < 0.05]. Inhaled NO resulted in a significant, reversible, dose-dependent, selective reduction in PAP from 5.5(5.2/6.0) kPa at control to 5.1(4.7/5.6) kPa at 1 ppm, 4.9(4.3/5.3) kPa at 4 ppm, and to 4.7(4.1/5.1) kPa at 8 ppm. PaO2 increased from 12.7(10.4/17.1) to 19.2(12.4/26.0) kPa at 1 ppm NO, to 23.9(4.67/26.7) kPa at 4 ppm NO and to 24.5(11.9/28.7) kPa at 8 ppm NO. All patients responded to NO inhalation (either with PAP or PaO2), all were subject to long-term inhalation (1-19 days). All were successfully weaned from NO and were discharged from the intensive care unit.

CONCLUSION

The present study demonstrates that low-dose inhaled NO may be an effective drug for symptomatic treatment of hypoxemia and/or pulmonary hypertension due to allograft dysfunction subsequent to lung transplantation.

Surgical and chemotherapeutic treatment of alveolar echinococcosis in a dog

Surgical removal of macroscopically detectable metacestode tissue followed by postoperative chemotherapy according to established human protocols resulted in complete clinical remission and immediate normalization of hyperglobulinemia in a dog with alveolar echinococcosis (AE). The disease is caused by the metacestode stage of the cestode, Echinococcus multilocularis. In endemic areas, AE should be included in the differential diagnosis of polycystic liver masses, especially if concomitant hyperglobulinemia is present. However, the importance of AE is not only the disease of the single dog itself but also the potential risk of infection for humans in an endemic area.

Hypoxia activates ATP-dependent potassium channels in inspiratory neurones of neonatal mice

1. The respiratory centre of neonatal mice (4 to 12 days old) was isolated in 700 micro(m) thick brainstem slices. Whole-cell K+ currents and single ATP-dependent potassium (KATP) channels were analysed in inspiratory neurones. 2. In cell-attached patches, KATP channels had a conductance of 75 pS and showed inward rectification. Their gating was voltage dependent and channel activity decreased with membrane hyperpolarization. Using Ca2+-containing pipette solutions the measured conductance was lower (50 pS at 1.5 mM Ca2+), indicating tonic inhibition by extracellular Ca2+. 3. KATP channel activity was reversibly potentiated during hypoxia. Maximal effects were attained 3-4 min after oxygen removal from the bath. Hypoxic potentiation of open probability was due to an increase in channel open times and a decrease in channel closed times. 4. In inside-out patches and symmetrical K+ concentrations, channel currents reversed at about 0 mV. Channel activity was blocked by ATP (300-600 microM), glibenclamide (10-70 microM) and tolbutamide (100-300 microM). 5. In the presence of diazoxide (10-60 microM), the activity of KATP channels was increased both in inside-out, outside-out and cell-attached patches. In outside-out patches, that remained within the slice after excision, the activity of KATP channels was enhanced by hypoxia, an effect that could be mediated by a release of endogenous neuromodulators. 6. The whole-cell K+ current (IK) was inactivated at negative membrane potentials, which resembled the voltage dependence of KATP channel gating. After 3-4 min of hypoxia, K+ currents at both hyperpolarizing and depolarizing membrane potentials increased. IK was partially blocked by tolbutamide (100-300 microM) and in its presence, hypoxic potentiation of IK was abolished. 7. We conclude that KATP channels are involved in the hypoxic depression of medullary respiratory activity.

[Surgical interventions in extracorporeal membrane oxygenation (ECMO)]

Extracorporeal membrane oxygenation is a suitable technique for short-term treatment of resistant respiratory failure with a comparably low mortality rate of 32%. However, pulmonary complications are quite often encountered during ECMO therapy making thoracic interventions necessary. The most frequent of these complications is hemorrhage followed by lung fistula, which remain resistant to conventional therapy. The indication for operative lung resection during ECMO treatment must remain restricted to selected cases, since these procedures have a high morbidity.

Health-related quality of life and posttraumatic stress disorder in survivors of the acute respiratory distress syndrome

OBJECTIVES

Despite considerable progress in intensive care management of the acute respiratory distress syndrome (ARDS), little is known about health-related quality of life in long-term survivors. In addition, intensive care treatment can be extremely stressful, and many survivors of ARDS report adverse experiences such as respiratory distress, anxiety, or pain during intensive care unit (ICU) treatment. This study was performed to assess health-related quality of life in survivors of ARDS and to test the hypothesis that adverse experiences during ICU treatment result in posttraumatic stress disorder (PTSD) and negative effects on health-related quality of life.

DESIGN

Retrospective, cohort, case-controlled analyses.

SETTING

A 12-bed multidisciplinary ICU of a tertiary care university hospital, capable of providing extracorporeal life support for adults with severe ARDS.

PATIENTS

We studied 80 patients who were admitted to our hospital from 1985 to 1995 and who survived an episode of ARDS. ARDS was defined according to the criteria of the American-European Consensus Conference on ARDS.

INTERVENTIONS

Health-related quality of life was measured using the Health Status Questionnaire of the self-administered Medical Outcomes Study Short Form Survey that consists of 36 questions (SF-36) and the German version of the Post Traumatic Stress Syndrome 10-Questions Inventory (PTSS-10), a self-report scale for the diagnosis of posttraumatic stress disorder based on the Diagnostic and Statistical Manual (Third Edition) criteria (American Psychiatric Association). The number of adverse experiences (anxiety, respiratory distress, pain, and nightmares) during intensive care was evaluated by means of a structured questionnaire. For each patient with ARDS, three age- and gender-comparable controls were randomly selected from databases providing normal values for the SF-36 and PTSS-10 scores in populations at risk for posttraumatic stress disorder.

MEASUREMENTS AND MAIN RESULTS

Survivors of ARDS showed statistically significant impairments in all eight health dimensions of the SF-36 when compared with normal controls (median reduction 21.3%, p < .006) with maximal impairments in physical function (median reduction 28.9%, p = .000) and a 38% higher frequency of chronic pain (p = .0001). Three of 34 patients reporting none, or one, adverse experience had evidence of posttraumatic stress disorder vs. 19 of 46 patients remembering multiple traumatic episodes (p = .007). Patients reporting multiple adverse experiences described the lowest health-related quality of life, with maximal impairments in psychosocial functioning (p < .005) and only small limitations in physical function.

CONCLUSIONS

Long-term survivors of ARDS describe a good overall health-related quality of life. Major impairments in mental health domains of health-related quality of life are associated with the development of posttraumatic stress disorder and are a possible result of traumatic experiences during ICU therapy.

Comparison of secretory responses as measured by membrane capacitance and by amperometry

We have compared capacitance and amperometric measurements in bovine chromaffin cells when secretion was elicited by flash photolysis of caged-calcium or step depolarizations. Total amperometric charge depended linearly on the amount of capacitance increase in both types of experiments. Furthermore, the properties of resolvable amperometric spikes after flashes were comparable to those observed after depolarizations, and their timing was compatible with the rate of capacitance increase. For a more detailed comparison, we used Monte Carlo simulations of multiple amperometric events occurring randomly over the surface of a sphere and summing together, to generate a reference amperometric signal for a given measured capacitance increase. Even after correction for endocytotic processes, the time courses of the integrated experimental records lagged behind the integrated Monte Carlo records by approximately 50 ms in flash and depolarization experiments. This delay was larger by approximately 40 ms than what can be expected from the "pre-foot delay" or the foot duration. Possible sources for the remaining delay could be diffusional barriers like the patch-pipette and the chamber bottom, which are not taken into account in the model. We also applied a novel type of fluctuation analysis to estimate the relative quantum size of an amperometric event. On average the estimates from experimental amperometric traces, in both flash and depolarization experiments, were 3-5 times smaller than estimates from simulated ones. This discrepancy can be due to contributions to the amperometric current from small vesicles, preferred release from cellular regions orientated toward the chamber bottom, or abundance of "foot-only" events. In conclusion, amperometric signals in flash and depolarization experiments displayed similar delayed average time courses and a lower estimate for the relative quantum size compared to the modeled amperometric signals. However, individual amperometric spikes were in agreement with expectations derived from capacitance signals.

Single-injection inulin clearance--a simple method for measuring glomerular filtration rate in dogs

The glomerular filtration rates (GFR) of 93 dogs of different breeds with a broad range of bodyweight were determined using an inulin single-injection method. Fifty-two dogs were used as controls, 21 dogs had suspected renal disease but serum creatinine in the normal range, and 20 dogs had elevated serum creatinine levels and a low urine specific gravity due to renal disease. Inulin was injected intravenously at a dosage of 100 mg kg(-1) bodyweight or 3000 mg m(-2) body surface. Blood samples were taken before and three, 20, 40, 80 and 120 minutes after injection. The total clearance was calculated from the decrease in the serum concentration of inulin using a two-compartment model. The range of GFR values was 83.5-144.3 ml min(-1) m(-2) in control dogs, 60.2-96.7 ml min(-1) m(-2) in dogs with suspected renal disease, 50.0-76.2 ml min(-1) m(-2) in dogs with suspected renal disease and polyuria/polydipsia, and 16.3-63.0 ml min(-1) m(-2) in dogs with azotaemic renal disease. The study indicates that single-injection inulin clearance is a cheap and simple tool for GFR measurements in small animal practice.

Perioperative management of patients undergoing lung transplantation

This review focuses on recent developments in the perioperative management of patients undergoing lung transplantation. Relevant current literature and the experience of the Munich Lung Transplant Group were taken into consideration. Recent advances include the use of inhalational nitric oxide for the treatment of early graft dysfunction and the use of aerosolized cyclosporine for the treatment of recurrent and steroid-resistant acute rejection. Opportunistic infections remain a major source of morbidity and mortality in lung transplant recipients.

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.

[Health-related quality of life. Long-term survival in patients with ARDS following extracorporeal membrane oxygenation (ECMO)]

Treatment of severe acute respiratory distress syndrome (ARDS) with extracorporeal membrane oxygenation (ECMO) can be lifesaving but requires maximal use of intensive care resources over prolonged periods of time, resulting in high costs. Little is known about the health-related quality of life (HRQL) in long-term survivors. This case-controlled retrospective study was designed to assess the health-related quality of life in long-term survivors of ARDS and ECMO-therapy.

METHODS

14 long-term survivors of ARDS (APACHE II score = 24, Lung Injury Score = 3.25, median values) treated using ECMO between 1992 and 1995 (median time interval between data collection and discharge from the ICU 16 months) and 14 ARDS-patients conventionally treated during the same period (group I) were identified and completed the SF-36 Health Status Questionnaire (Medical Outcome Trust, Boston, USA). 14 healthy subjects (group II) were drawn at random from a large data base generated to provide normal values for the SF-36 in a German population. All three groups were comparable with respect to sex and age.

RESULTS

Long-term survivors of ECMO-therapy reported significant reductions in physical functioning when compared with patients treated by mechanical ventilation alone (group I, -12.5%, p < 0.05) and with healthy controls (group II, -50%, p < 0.05) and showed a higher incidence of chronic physical pain (+5% and +24%, respectively, p < 0.05). There were no differences with regard to the mental health dimensions of the SF-36 (e.g. vitality, mental health index or social functioning) between ECMO-patients and all controls. Nine patients (64.3%) from the ECMO group versus all patients treated conventionally (group I) had full-time employment (p = 0.46, Chi2 test).

CONCLUSIONS

The majority of long-term survivors of ECMO-treatment show good physical and social functioning, including a high rate of employment. The more aggressive approach of ECMO-therapy and a possibly more severe underlying disease process may explain impairments in health-related quality of life outcomes after ECMO-treatment. Despite these limitations, long-term survivors of ECMO-therapy are able to reach a highly satisfactory health-related quality of life.

Extra protein loss not caused by surgical bleeding in patients with ovarian cancer

BACKGROUND

[corrected] Clinical experience in patients with ovarian cancer has shown special difficulties in maintaining cardiovascular stability during surgery.

METHODS

To evaluate the causes for this observation, 15 patients with benign ovarian tumours (group I) and 13 patients with ovarian cancer (group II) were investigated perioperatively. Plasma volume (indocyanine green-dilution technique), haematocrit, plasma protein concentration, mean arterial pressure, heart rate, and central venous pressure were measured immediately before and after cytoreductive surgery.

RESULTS

Normal values of blood-, plasma-, and red cell volume were determined preoperatively in both groups, and in relation to body surface area there were no intergroup differences of these parameters. In group I, the significant decrease in red cell volume of 313 ml postoperatively was compensated for by an increase in plasma volume of 371 ml (median values). In contrast to group I, the decrease in red cell volume of 328 ml in group II was not related to a significant increase in plasma volume, so that blood volume postoperatively was 483 ml lower than preoperatively, although the same standardized infusion regimen as in group I was applied. Patients of group II had a significantly higher loss of intravascular protein (49 g vs 13 g in group I), which left the intravascular space by another way than by surgical bleeding. This extra protein loss is termed Intraoperative Protein Shift (IPS).

CONCLUSION

IPS could be an important quantity in perioperative fluid balance. We assume that different surgical procedures predispose to occurrence of differing amounts of IPS.

Nucleotide hydrolysis-dependent conformational changes in p21(ras) as studied using ESR spectroscopy

We have employed ESR spectroscopy using guanine nucleotides that contain a spin label at the 2',3'-position of the ribose to investigate structural changes in the proto-oncogene product p21(ras) that are dependent on nucleotide hydrolysis. The three nucleotide analogs used were 2',3'-(2,2,5, 5-tetramethyl-3-pyrroline-1-oxyl-3-carboxylic acid ester (SL) GTP, SL-GDP, and the non-hydrolyzable analog SL-guanylylimidodiphosphate. SL-GTP was hydrolyzed by p21 with rates similar to those for GTP hydrolysis and appears to be an excellent substrate analog. The ESR spectra of SL-GTP and SL-GDP in complex with p21 differ significantly when acquired at 0 degrees C or 5 degrees C indicating different environments (conformations) of the protein-bound radicals depending on the phosphorylation state of the bound nucleotide. We calculated the rate constant for the conformational change as deduced from the changes in the corresponding ESR spectra upon incubation of the p21.SL-GTP complex at 25 degrees C and compared it to the rate constant of hydrolysis of SL-GTP at the same temperature. The rate constant deduced from the ESR method was similar to that determined by a high performance liquid chromatography technique. The data are in agreement with the idea that a conformational change during GTP hydrolysis by p21 occurs simultaneously with the actual hydrolysis step.

[ARDS and Wegener granulomatosis]

Wegener's granulomatosis is a distinct clinicopathologic entity characterized by granulomatous vasculitis of the upper and lower respiratory tract and glomerulonephritis. This disease can present as a clinical picture which resembles sepsis and adult respiratory distress syndrome (ARDS). Wegener's disease requires immunosuppression which can have detrimental consequences when used in sepsis. The following case report illustrates the diagnostic difficulties encountered by intensive care physicians treating severe pulmonary failure and multiple organ dysfunction in Wegener's granulomatosis appearing as ARDS with sepsis.

CASE REPORT

A 19-year-old female patient had developed acute respiratory and renal failure after a prolonged period (many months) of antibiotic resistant otitis, sinusitis and mastoiditis. The patient had required intubation at another hospital and there was a history of tension pneumothorax and cardiopulmonary resuscitation during mechanical ventilation. Emergency extracorporeal membrane oxygenation (ECMO) for acute hypercapnic and hypoxic respiratory failure was instituted and the patient was transported to our institution while on ECMO. The patient was treated empirically for suspected pulmonary and systemic infection and received hydrocortisone (0.18 mg/kg/h) as part of a protocol-driven treatment of septic shock in addition to antibiotic and antimycotic regime. The use of ECMO was required for 10 and mechanical ventilation for another 50 days after admission. After successful extubation, central nervous system dysfunction became evident with a somnolent and generally unresponsive patient. When the hydrocortisone dose was gradually tapered, the clinical status of the patient further deteriorated, pulmonary gas exchange worsened and she developed renal failure with proteinura and hematuria. A renal biopsy was performed demonstrating vasculitis and focal segmental glomerulonephritis, a systemic granulomatous vasculitis was suspected; the serum was tested for anti-proteinase 3 antibodies (PR3-ANCA) and turned out to be positive (17.5 U/ml; normal range < 7 U/ml). The morphologic findings from renal biopsy, the positive test for antiproteinase 3 antibodies and the pulmonary-renal involvement with evidence of multisystem disease established the diagnosis of Wegener's granulomatosis. Immunosuppressive therapy with cyclophosphamide and prednisolone was instituted resulting in rapid improvement with recovery of pulmonary, renal and central nervous system function within two weeks. The use of ECMO in this patient served as a life-saving immediate measure usefull to "buy time" until a definite diagnosis could be established. ARDS represents an uniform pulmonary reaction to a large number of different noxious stimuli and disease entities. This case demonstrates that intensive care physicians caring for critically ill patients with ARDS should include even rare causes of pulmonary injury into their differential diagnosis.

Red cell transfusion therapy in the critical care setting

According to our own experience and published reports the frequency of red cell transfusion in intensive care units is in the range of 0.2 to 0.4 units per patient per day and is dependent upon the local strategy, the patients involved and the kind of surgery performed. The rationale for red cell transfusion is to maintain or restore the oxygen carrying capacity of the blood to avoid tissue hypoxia which occurs when oxygen delivery drops below a certain critical value. Besides bleeding, phlebotomy is also a significant source of blood loss in critically ill patients. According to several recent reviews and consensus articles there is no basis for a fixed indicator for transfusion, such as a haemoglobin concentration of < 100 gL-1. The decision to transfuse has to be made according to the patients individual status. The major adaptive mechanism in response to acute anaemia is an increase in cardiac output and hence blood flow to tissues. As a consequence even moderate degrees of acute anaemia may not be tolerated by patients with cardiac disease, whilst marked anaemia carries a considerable risk of ischaemia in patients with brain lesions or cerebral arterial stenoses. In critically ill patients it has been postulated that supply dependency of oxygen consumption occurs over a wide range of oxygen delivery, far above the critical values of oxygen delivery seen under normal conditions. Maximising oxygen delivery was therefore formulated as a goal in these patients. However, whether pathological supply dependency of oxygen delivery really exists in critically ill patients is still under discussion and recent studies found no benefit in maximising oxygen delivery to this patient group. However, individualised triggers for red blood cell transfusion are adequate for critically ill patients considering their co-morbidities and severity of disease. Finally, the decision to transfuse must also take into account the potential risks (infectious and non-infectious), as well as benefits for the individual patient. In the future, the level of transfusions may be reduced by using blood sparing techniques such as blood withdrawal in closed systems, bedside microchemistry, intravascular monitors, or autotransfusion of drainage blood in intensive care units.