Dead space ventilation promotes alveolar hypocapnia reducing surfactant secretion by altering mitochondrial function.

BACKGROUND: In acute respiratory distress syndrome (ARDS), pulmonary perfusion failure increases physiologic dead space ventilation (VD/VT), leading to a decline of the alveolar CO2 concentration [CO2]iA. Although it has been shown that alveolar hypocapnia contributes to formation of atelectasis and surfactant depletion, a typical complication in ARDS, the underlying mechanism has not been elucidated so far. METHODS: In isolated perfused rat lungs, cytosolic or mitochondrial Ca2+ concentrations ([Ca2+]cyt or [Ca2+]mito, respectively) of alveolar epithelial cells (AECs), surfactant secretion and the projected area of alveoli were quantified by real-time fluorescence or bright-field imaging (n=3-7 per group). In ventilated White New Zealand rabbits, the left pulmonary artery was ligated and the size of subpleural alveoli was measured by intravital microscopy (n=4 per group). Surfactant secretion was determined in the bronchoalveolar lavage (BAL) by western blot. RESULTS: Low [CO2]iA decreased [Ca2+]cyt and increased [Ca2+]mito in AECs, leading to reduction of Ca2+-dependent surfactant secretion, and alveolar ventilation in situ. Mitochondrial inhibition by ruthenium red or rotenone blocked these responses indicating that mitochondria are key players in CO2 sensing. Furthermore, ligature of the pulmonary artery of rabbits decreased alveolar ventilation, surfactant secretion and lung compliance in vivo. Addition of 5% CO2 to the inspiratory gas inhibited these responses. CONCLUSIONS: Accordingly, we provide evidence that alveolar hypocapnia leads to a Ca2+ shift from the cytosol into mitochondria. The subsequent decline of [Ca2+]cyt reduces surfactant secretion and thus regional ventilation in lung regions with high VD/VT. Additionally, the regional hypoventilation provoked by perfusion failure can be inhibited by inspiratory CO2 application.

Prehospital non-invasive ventilation in acute respiratory failure is justified even if the distance to hospital is short.

AIMS: Evaluation of the efficacy of prehospital non-invasive ventilation (NIV) in patients with acute exacerbation of chronic obstructive pulmonary disease (COPD) and cardiogenic pulmonary edema (CPE). MATERIAL AND METHODS: Consecutive patients who were prehospitally treated by Emergency Physicians using NIV were prospectively included. A step-by-step approach escalating NIV-application from continuous positive airway pressure (CPAP) to continuous positive airway pressure supplemented by pressure support (CPAP-ASB) and finally bilevel inspiratory positive airway pressure (BIPAP) was used. Patients were divided into two groups according to the prehospital NIV-treatment-time (NIV-group 1: ≤15 min, NIV-group 2: >15 min). In addition, a historic control group undergoing standard care was created. Endpoints were heart rate, peripheral oxygen saturation, breathing rate, systolic blood pressure, and a dyspnea score. RESULTS: A total of 99 patients were analyzed (NIV-group 1: n = 41, NIV-group 2: n = 58). The control group consisted of 30 patients. The majority of NIV-patients (90%) received CPAP-ASB, while CPAP without ASB was conducted in 8% and BIPAP-ventilation in 2% of all cases. Technical application of NIV lasted 6.1 ±â€¯3.8 min. NIV-treatment-time was as follows: NIV-group 1: 13.1 ±â€¯3.2 min, NIV-group 2: 22.8 ±â€¯5.9 min. Differences between baseline- and hospital admission values of all endpoints showed significantly better improvement in NIV-groups compared to the control group (p < 0.001). The stabilizing effect of NIV in terms of vital parameters was comparable between both NIV-groups, independent of the duration of treatment (n.s.). CONCLUSION: Prehospital NIV-treatment should be performed in patients with COPD-exacerbation and CPE, even if the distance between emergency scene and hospital is short.

IDH3 mediates apoptosis of alveolar epithelial cells type 2 due to mitochondrial Ca2+ uptake during hypocapnia.

In adult respiratory distress syndrome (ARDS) pulmonary perfusion failure increases physiologic dead-space (VD/VT) correlating with mortality. High VD/VT results in alveolar hypocapnia, which has been demonstrated to cause edema formation, atelectasis, and surfactant depletion, evoked, at least in part, by apoptosis of alveolar epithelial cells (AEC). However, the mechanism underlying the hypocapnia-induced AEC apoptosis is unknown. Here, using fluorescent live-cell imaging of cultured AEC type 2 we could show that in terms of CO2 sensing the tricarboxylic acid cycle enzyme isocitrate dehydrogenase (IDH) 3 seems to be an important player because hypocapnia resulted independently from pH in an elevation of IDH3 activity and subsequently in an increase of NADH, the substrate of the respiratory chain. As a consequence, the mitochondrial transmembrane potential (ΔΨ) rose causing a Ca2+ shift from cytosol into mitochondria, whereas the IDH3 knockdown inhibited these responses. Furthermore, the hypocapnia-induced mitochondrial Ca2+ uptake resulted in reactive oxygen species (ROS) production, and both the mitochondrial Ca2+ uptake and ROS production induced apoptosis. Accordingly, we provide evidence that in AEC type 2 hypocapnia induces elevation of IDH3 activity leading to apoptosis. This finding might give new insight into the pathogenesis of ARDS and may help to develop novel strategies to reduce tissue injury in ARDS.

Sedation for advanced procedures in the bronchoscopy suite: proceduralist or anesthesiologist?

PURPOSE OF REVIEW: This article focuses on the issue of sedation provided either by proceduralists or anesthesiologists for advanced bronchoscopy procedures. The relative merits of both approaches are presented. Current evidence from the literature and guideline recommendations relevant to this topic are reviewed. RECENT FINDINGS: In general, patient and proceduralist satisfaction as well as patient safety are increased when intravenous sedation is provided for advanced bronchoscopic procedures. However, guidelines by various societies remain vague on defining the appropriate level of care required when providing sedation for these procedures. In addition, targeted depth of sedation varies considerably among practitioners. While in some settings, nonanesthesiologist-administered propofol sedation has been proven safe; nevertheless, its use is controversial, especially in the bronchoscopy suite. SUMMARY: The role of the anesthesiologist in sedation for advanced bronchoscopy remains undefined. When deep sedation for prolonged interventional procedures is needed or when dealing with patients who have multiple comorbidities, an anesthesiologist should be involved.

Perioperative fluid therapy: defining a clinical algorithm between insufficient and excessive.

In the perioperative scenario, adequate fluid and volume therapy is a challenging task. Despite improved knowledge on the physiology of the vascular barrier function and its respective pathophysiologic disturbances during the perioperative process, clear-cut therapeutic principles are difficult to implement. Neglecting the physiologic basis of the vascular barrier and the cardiovascular system, numerous studies proclaiming different approaches to fluid and volume therapy do not provide a rationale, as various surgical and patient risk groups, and different fluid regimens combined with varying hemodynamic measures and variable algorithms led to conflicting results. This review refers to the physiologic basis and answers questions inseparably conjoined to a rational approach to perioperative fluid and volume therapy: Why does fluid get lost from the vasculature perioperatively? Whereto does it get lost? Based on current findings and rationale considerations, which fluid replacement algorithm could be implemented into clinical routine?

[Drowning - An update on prehospital and intrahospital treatment strategies]. / Update Ertrinkungsunfall - Präklinische und klinische Therapiestrategien.

500000 people die from unintentional drowning each year worldwide. Drowning accidents occur to humans of every age, while fatal drowning is the leading cause of death among boys 5 to 14 years of age. In Germany, however, most drowning victims are elderly people. Considering the multitude of accident settings, ranging from bathing accidents in lakes to shipwrecks at sea, professional first responders need to adapt to various scenarios. This article summarizes the pathophysiology of drowning, particular features of prehospital life support and current knowledge on the further therapy of victims of near fatal drowning accidents.

[Anesthesia in interventional pulmonology -- endoscopic interventions: part 2]. / Anästhesie in der interventionellen Pneumologie - Endoskopische Interventionen: Teil 2.

Endobronchial ultrasound-guided transbronchial needle aspiration can be used efficiently for pathological diagnosis of bronchial walls and surrounding structures. Patients with hemoptysis, fistulas or foreign-body-aspiration can be treated bronchoscopically, but remain a challenge for the hospital team involved.

[Anesthesiology in interventional pneumology- endoscopic interventions: part 1]. / Anästhesie in der interventionellen Pneumologie - Endoskopische Interventionen: Teil 1.

Less invasive bronchoscopic techniques for lung-volume-reduction have almost replaced surgical resections. Tracheobronchial obstructions and - to a certain degree - even bronchial tumors can be treated bronchoscopically. However all these procedures show specific risks anesthesiologists have to consider.

[Anesthesia in interventional pulmonology -- bronchoscopy and jet ventilation]. / Anästhesie in der interventionellen Pneumologie--Bronchoskopie und Jet-Ventilation.

Today interventional procedures are frequently used for diagnosis and treatment in patients with various pulmonary diseases. Besides bronchoscopy in local- or general anesthesia jet-ventilation is commonly applied via catheter or rigid bronchoscope. Anesthesiologists should have profound knowledge of high-frequency ventilation and possible complications when assisting during interventional procedures.

[Anaesthesia for extrathoracal vascular surgery - Part 2: anaesthesiological management]. / Anästhesie in der extrathorakalen Gefäßchirurgie - Teil 2: Anästhesiologisches Management.

The anaesthesiological management in patients undergoing vascular surgical procedure need an individual approach, because of the high incidence of coexisting diseases with an increased risk of cardiovascular complications. The choice of anaesthesiogical method und perioperative monitoring depends on planned vascular procedures.

[Anaesthesia for extrathoracal vascular surgical procedures - part 1: optimization on the preoperative therapy]. / Anästhesie in der extrathorakalen Gefäßchirurgie - Teil 1: Präoperative Therapieoptimierung.

Vascular surgical patients have an increased perioperative risk for cardiovascular complications because of high incidence of cardiovascular risk factors. An optimization of the preoperative therapy is able to reduce the preventable cardiac complications. Cardiovascular risk factors such as high blood pressure, diabetes mellitus, heart failure have to be identified and treated.

Laryngeal dislocation after ventral fusion of the cervical spine.

We report on a 70-year-old patient who underwent ventral fusion of the cervical spine (C3/4 and C4/5) for spinal canal stenosis performed by the neurosurgery department. The patient suffered an exceedingly rare complication of the surgery - laryngeal dislocation. Had the deformed laryngeal structures been overlooked and the patient extubated as usual after surgery, reintubation would have been impossible due to the associated swelling, which might have had disastrous consequences. Leftward dislocation of the larynx became apparent post-operatively, but prior to extubation. Extubation was therefore postponed and a subsequent computed tomography (CT) scan revealed entrapment of laryngeal structures within the osteosynthesis. A trial of repositioning using microlaryngoscopy performed by otolaryngology (ears, nose and throat) specialists failed, making open surgical revision necessary. At surgery, the entrapped laryngeal tissue was successfully mobilised. Laryngeal oedema developed despite prompt repositioning; thus, necessitating tracheotomy and long-term ventilation. Laryngeal dislocation may be an unusual cause of post-operative neck swelling after anterior cervical spine surgery and should be considered in the differential diagnosis if surgical site haematoma and other causes have been ruled out. Imaging studies including CT of the neck may be needed before extubation to confirm the suspicion and should be promptly obtained to facilitate specific treatment.

Quality of postoperative pain using an intraoperatively placed epidural catheter after major lumbar spinal surgery.

BACKGROUND: Major spinal surgery is associated with high postoperative pain scores and opioid requirement. The aim of the current prospective, randomized, placebo-controlled, double-blind study was to assess the reduction of opioid requirement and pain scores using an intraoperatively placed epidural catheter with infusion of 0.1% ropivacaine during the postoperative period. METHODS: Thirty patients undergoing major lumbar spinal surgery from a dorsal approach were included in this study. Before wound closure, the orthopedic surgeon inserted an epidural catheter. Postoperatively, patients were randomly assigned to receive an infusion of 12 ml/h ropivacaine, 0.1% (group R), or 12 ml/h saline (group N) after an initial bolus of 10 ml of the respective study solution. Additional pain relief was provided using an intravenous patient-controlled analgesia pump with the opioid piritramide. Patients were assessed with respect to pain scores (visual analog scale of 0-100), cumulative opioid requirement, side effects, and satisfaction with pain management. RESULTS: : Demographic data, duration of surgery, and type of surgery were comparable between groups. Pain scores were assessed as follows (group R vs. group N: 6 h: 24 +/-20 vs. 51 +/- 20, P = 0.002; 24 h: 33 +/- 19 vs. 53 +/- 27, P = 0.04; 48 h: 21 +/-17 vs. 40 +/- 26, P = 0.04; 72 h: 14 +/- 13 vs. 38 +/- 25, P = 0.02). The cumulative piritramide requirement after 72 h was 97 +/- 23 mg in group R and 157 +/-72 mg in group N (P = 0.03). The incidence of side effects was comparable between groups, and patient satisfaction was always higher in group R (P < 0.05). CONCLUSION: Continuous epidural infusion of 0.1% ropivacaine results in lower pain scores and opioid consumption and higher patient satisfaction when compared with placebo. Application of ropivacaine using an epidural catheter seems to be a highly effective treatment for postoperative pain after major lumbar spinal surgery.