[Renal cortical necrosis after application of tranexamic acid in peripartal hemorrhage]. / Renale Rindennekrose nach Gabe von Tranexamsäure bei geburtsassoziierter Blutung.

HISTORY: A 28-years old patient delivers a daughter by primary caesarian section (41. WOP) in breech presentation after a complication-free pregnancy except increased blood pressure readings at the morning of caesarian section. During the caesarian section a major bleeding of the atonic uterus with hemorrhagic shock appears. Haemostasis is achieved by mechanical tamponade, the application of red blood cell concentrates and the substitution of clotting factors, also tranexamic acid. Because of an anuric renal failure due to the shock hemodialysis is initiated. EXAMINATIONS/FINDINGS: Clinical examination and blood tests show the constellation of a thrombotic microangiopathy. There are no hints for a thrombotic thrombocytopenic purpura (TTP) or a hemolytic-uremic syndrome (HUS). In addition, a genetic testing gives no hints for an atypical HUS. After 4 weeks of dialysis duty a renal biopsy is performed. The renal biopsy shows a partly reversible tubular damage with an older ischemic cortical necrosis. DIAGNOSIS/THERAPY: In the further course the resumption of the diuresis can be observed. The dialysis treatment has to be continued because of an insufficient excretory renal function. Fortunately a living-donor kidney transplantation (mother) can be carry out successfully already one year after the hemorrhagic shock. CONCLUSION: The combination of peripartal bleeding with hemorrhagic shock, possibly aggravated by (pre-)eclampsia or HELLP-syndrome, and the application of tranexamic acid with its prothrombotic effect seems to be responsible for the major renal cortical necrosis.

Minimal-flow ECCO2R in patients needing CRRT does not facilitate lung-protective ventilation.

Extracorporeal CO2 removal (ECCO2R) is intended to facilitate lung protective ventilation in patients with hypercarbia. The combination of continuous renal replacement therapy (CRRT) and minimal-flow ECCO2R offers a promising concept for patients in need of both. We hypothecated that this system is able to remove enough CO2 to facilitate lung protective ventilation in mechanically ventilated patients. In 11 ventilated patients with acute renal failure who received either pre- or postdilution CRRT, minimal-flow ECCO2R was added to the circuit. During 6 h of combined therapy, CO2 removal and its effect on facilitation of lung-protective mechanical ventilation were assessed. Ventilatory settings were kept in assisted or pressure-controlled mode allowing spontaneous breathing. With minimal-flow ECCO2R significant decreases in minute ventilation, tidal volume and paCO2 were found after one and three but not after 6 h of therapy. Nevertheless, no significant reduction in applied force was found at any time during combined therapy. CO2 removal was 20.73 ml CO2/min and comparable between pre- and postdilution CRRT. Minimal-flow ECCO2R in combination with CRRT is sufficient to reduce surrogates for lung-protective mechanical ventilation but was not sufficient to significantly reduce force applied to the lung. Causative might be the absolute amount of CO2 removal of only about 10% of resting CO2 production in an adult as we found. The benefit of applying minimal flow ECCO2R in an uncontrolled setting of mechanical ventilation might be limited.

Electrical activity of the diaphragm (EAdi) as a monitoring parameter in difficult weaning from respirator: a pilot study.

INTRODUCTION: A reliable prediction of successful weaning from respiratory support may be crucial for the overall outcome of the critically ill patient. The electrical activity of the diaphragm (EAdi) allows one to monitor the patients' respiratory drive and their ability to meet the increased respiratory demand. In this pilot study, we compared the EAdi with conventional parameters of weaning failure, such as the ratio of respiratory rate to tidal volume. METHODS: We studied 18 mechanically ventilated patients considered difficult to wean. For a spontaneous breathing trial (SBT), the patients were disconnected from the ventilator and given oxygen through a T-piece. The SBT was evaluated by using standard criteria. RESULTS: Twelve patients completed the SBT successfully, and six failed. The EAdi was significantly different in the two groups. We found an early increase in EAdi in the failing patients that was more pronounced than in any of the patients who successfully passed the SBT. Changes in EAdi predicted an SBT failure earlier than did conventional parameters. CONCLUSIONS: EAdi monitoring adds valuable information during weaning from the ventilator and may help to identify patients who are not ready for discontinuation of respiratory support.

Effects of high-frequency oscillatory ventilation on systemic and cerebral hemodynamics and tissue oxygenation: an experimental study in pigs.

BACKGROUND: In this study, we compare the effects of high frequency oscillatory ventilation (HFOV) with those of lung-protective volume-controlled ventilation (VCV) on cerebral perfusion, tissue oxygenation, and cardiac function with and without acute intracranial hypertension (AICH). METHODS: Eight pigs with healthy lungs were studied during VCV with low tidal volume (V(T): 6 ml kg(-1)) at four PEEP levels (5, 10, 15, 20 cm H(2)O) followed by HFOV at corresponding transpulmonary pressures, first with normal ICP and then with AICH. Systemic and pulmonary hemodynamics, cardiac function, cerebral perfusion pressure (CPP), cerebral blood flow (CBF), cerebral tissue oxygenation, and blood gases were measured after 10 min at each level. Transpulmonary pressures (TPP) were calculated at each PEEP level. The measurements were repeated with HFOV using continuous distending pressures (CDP) set at TPP plus 5 cm H(2)O for the corresponding PEEP level. Both measurement series were repeated after intracranial pressure (ICP) had been raised to 30-40 cm H(2)O with an intracranial balloon catheter. RESULTS: Cardiac output, stroke volume, MAP, CPP, and CBF were significantly higher during HFOV at normal ICP. Systemic and cerebral hemodynamics was significantly altered by AICH, but there were no differences attributable to the ventilatory mode. CONCLUSION: HFOV is associated with less hemodynamic compromise than VCV, even when using small tidal volumes and low mean airway pressures. It does not impair cerebral perfusion or tissue oxygenation in animals with AICH, and could, therefore, be a useful ventilatory strategy to prevent lung failure in patients with traumatic brain injury.

Influence of body position, PEEP and intra-abdominal pressure on the catheter positioning for neurally adjusted ventilatory assist.

PURPOSE: Neurally adjusted ventilatory assist (NAVA) relies on the patient's electrical activity of the diaphragm (EAdi) for actuating the ventilator. Thus a reliable positioning of the oesophageal EAdi catheter is mandatory. We aimed to evaluate the effects of body position (BP), positive end-expiratory pressure (PEEP) and intra-abdominal pressure (IAP) on catheter positioning. METHODS: Twenty-one patients were enrolled in this study. In six different situations [supine or 45° head of bed elevation (HBE) at PEEP 5 and 15 cmH(2)O; left lateral anti-decubitus at PEEP 5 cmH(2)O; supine at PEEP 5 cmH(2)O with abdominal surgical belt (ASB)] the catheter position was evaluated for the stability of the EAdi signal and information provided by a catheter positioning tool (highlighted electrical activity in central leads, absence of p waves in the distal lead). RESULTS: With an optimal catheter position EAdi signals were stable for all tested situations. During "45° PEEP 15" and "supine PEEP 15" absence of p waves in the distal lead revealed a difference compared with "supine PEEP 5" (p = 0.03), suggesting a caudal shift of the diaphragm relative to the oesophagus. The analysis of the highlighted electrical activity in the central leads supports this finding, revealing an influence of PEEP, BP and IAP on EAdi catheter position (p < 0.01). CONCLUSION: PEEP, BP and IAP may affect the EAdi catheter position, although not compromising a stable signal. Additional information as provided by the catheter positioning tool is needed to ensure an optimal EAdi catheter position.

Initial ventilation through laryngeal tube instead of face mask in out-of-hospital cardiopulmonary arrest is effective and safe.

INTRODUCTION: Bag-valve-mask ventilation is recommended as the initial airway management option for paramedics during cardiopulmonary resuscitation, although this technique requires considerable skill and is associated with the risk of stomach insufflation, regurgitation, and aspiration. The present two-phase study investigated the efficacy and safety of the laryngeal tube (LT-D) used by paramedics as the sole technique for ventilation in out-of-hospital cardiac arrest. METHODS: Paramedics staffing the emergency services' ambulances were selected for the study and trained in the use of the LT-D (phase I). They were then requested to use the device in patients requiring out-of-hospital cardiopulmonary resuscitation without prior bag-valve-mask ventilation. Patients were evaluated with regard to successful placement and effective ventilation using the airway. On arrival at the scene, the emergency physician replaced the LT-D with an endotracheal tube and assessed the incidence of regurgitation and injuries to the airways (phase II). RESULTS: Forty patients were enrolled into this study. One was excluded from analysis because of protocol violation. Insertion of the LT-D was successful and ventilation was effective in 33 patients (85%). Ventilation was not possible in six patients (15%) because of cuff rupture (n = 3) or massive regurgitation and aspiration before LT-D insertion (n = 3). No patient regurgitated after tube placement. No airway injuries were observed. The participants rated ventilation using the LT-D as effective. CONCLUSION: The LT-D is feasible and effective for airway management and ventilation when used by paramedics in out-of-hospital cardiopulmonary resuscitation and can be recommended as the sole technique in such situations.

Evaluation of the catheter positioning for neurally adjusted ventilatory assist.

PURPOSE: During neurally adjusted ventilatory assist (NAVA) the ventilator is driven by the patients electrical activation of the diaphragm (EAdi), detected by a special esophageal catheter. A reliable positioning of the EAdi-catheter is mandatory to trace a representative EAdi signal. We aimed to determine whether a formula that is based on the measurement from nose to ear lobe to xiphoid process of the sternum (NEX distance) modified for EAdi-catheter placement (NEX(mod)) is sufficient for predicting the accurate catheter position. METHODS: Twenty-six patients were enrolled in this study. The optimal EAdi-catheter position (OPT) was defined by: (1) stable EAdi signal, (2) electrical activity highlighted in central leads of the catheter positioning tool, and (3) absence of p-wave in distal lead. Afterwards NEX(mod) was calculated and compared to the OPT finding. RESULTS: At NEX(mod) the EAdi signal was suitable for running NAVA in 18 out of 25 patients (72%). NEX(mod) was identical with OPT in four patients (16%). NAVA was possible in all patients at OPT. Median OPT position was 2 cm caudal of the NEX(mod) ranging from 3 cm too cranial to a position 12 cm too caudal (P < 0.01). In one patient excluded from further analysis EAdi-catheter placement led to the diagnosis of bilateral injury of the phrenic nerves. CONCLUSIONS: EAdi-catheter placement based on the NEX(mod) formula allows running NAVA in about two-thirds of all patients. The additional tools provided are efficient and facilitate the correct positioning of the EAdi-catheter for neurally adjusted ventilatory assist.

LMA-ProSeal for elective postoperative care on the intensive care unit: a prospective, randomized trial.

BACKGROUND: Compared to an endotracheal tube, laryngeal mask airways are known to cause less hemodynamic alteration during the extubation phase of routine perioperative airway management. This study aims to examine the hypothesis that the LMA-ProSeal (PLMA, The Laryngeal Mask Company Limited, St. Helier, Jersey, Channel Islands) is an adequate tool for elective postoperative care in the intensive care unit (ICU) and potentially associated with less hemodynamic alteration during extubation in the ICU environment compared to an endotracheal tube. METHODS: Forty-eight patients were enrolled for this prospective randomized, controlled trial and were allocated to either control (ICU-T) or study group (ICU-P). In the ICU-P group, the endotracheal tube was replaced by a PLMA at the end of surgery. RESULTS: Forty-patients completed the study. Cardiovascular parameters increased significantly less in the ICU-P group: systolic blood pressure increased by 18.10 +/- 5.57 mmHg versus 34.65 +/- 5.63 mmHg (P < 0.05), mean arterial blood pressure increased by 11.23 +/- 3.25 mmHg versus 22.65 +/- 3.36 mmHg (P < 0.05), and heart rate increased by 9.3 +/- 2.9 versus 12.9 +/- 2.2 min (P < 0.05). Ventilation via the PLMA during transfer from the operation room to the ICU as well as during ICU stay was successful and without any adverse events. CONCLUSIONS: Removal of the PLMA after recovery from anesthesia was associated with less cardiovascular change compared to the endotracheal tube. Ventilation was possible without reported adverse events during the entire trial. Elective endotracheal tube replacement by the PLMA may be a useful procedure in selected patients.

Self-reported changes in attitude and behavior after attending a simulation-aided airway management course.

STUDY OBJECTIVE: To evaluate the influence of a simulator-aided course for airway management on participants' daily clinical airway management practice. DESIGN: Survey instrument. SETTING: University hospital. PARTICIPANTS: 88 participants who attended a simulator-aided course for airway management. INTERVENTION: Six mo after 4 consecutive courses with identical structure and content, participants were mailed a standardized questionnaire to answer. MEASUREMENTS AND MAIN RESULTS: Of 88 participants queried, 48 completed the questionnaire. Ninety-two percent had experienced a difficult airway situation in the 6 mo after the course. Fourteen (29%) evaluated predictors for a difficult airway more carefully. Fourteen (29%) established structural changes within their departments. Ten (21%) participants acquired new technical airway devices. The mean estimated impact on the participants' rating for lectures, skill stations, and scenarios on a scale from 1 (very helpful) to 6 (not at all helpful) was 2.8 for lectures, 1.6 for skill stations, and 1.4 for scenarios. CONCLUSIONS: Attendance at a simulator-aided airway management course has a significant impact on self-reported accuracy and confidence in evaluation of airways, use of alternative airway devices, and changes in the practitioner's clinical practice toward difficult airway situations.