Influence of xenon on pulmonary mechanics and lung aeration in patients with healthy lungs.

BACKGROUND: The anaesthetic xenon shows potent organ-protective properties. Due to high density and dynamic viscosity, peak inspiratory pressure (Pmax) increases during xenon application. Thus, barotrauma may counteract organ protection. Accordingly, we investigated the influence of xenon on lung mechanics and lung aeration in patients with normal and reduced thoracic wall compliance. METHODS: After registration and ethical approval, 20 patients free of pulmonary disease undergoing routine xenon-based anaesthesia were mechanically ventilated. The primary outcome variable transpulmonary pressure (Ptp) was determined from plateau pressure and intraoesophageal pressure before and after xenon wash-in. We recorded Pmax, and calculated airway resistance (RAW), and static (Cstat) and dynamic (Cdyn) respiratory compliances. Finally, lung aeration was quantified by electrical impedance tomography-derived centre of ventilation index (CVI) and global inhomogeneity index (GI) in the awake state, before and during xenon. RESULTS: Xenon increased Pmax [20.8 (SD 3) vs 22.6 (3) cm H2O, P<0.001] and RAW [0.9 (0.2) vs 1.4 (0.3) cm H2O litre-1 s, P<0.001], without affecting Ptp [1.5 (4) vs 2.0 (4) cm H2O, P=0.15]. While Cstat remained unchanged, Cdyn was reduced [33.9 (7) vs 31.2 (6) ml (cm H2O)-1, P<0.001). A ventral tidal volume shift after anaesthesia induction [CVI 0.53 (0.03) vs 0.59 (0.04), P<0.001] was unaltered during xenon [CVI 0.59 (0.04), P=0.29]. Homogeneity of lung aeration was also unchanged during xenon [GI 0.37 (0.03) vs 0.37 (0.03), P=0.99]. There were no clinically meaningful differential BMI-related effects. CONCLUSIONS: Xenon increases calculated airway resistance and peak inspiratory pressure without affecting transpulmonary pressure, independent of BMI. CLINICAL TRIAL REGISTRATION: NCT02682758.

Neuraxial block and postoperative epidural analgesia: effects on outcomes in the POISE-2 trial†.

BACKGROUND: We assessed associations between intraoperative neuraxial block and postoperative epidural analgesia, and a composite primary outcome of death or non-fatal myocardial infarction, at 30 days post-randomization in POISE-2 Trial subjects. METHODS: 10 010 high-risk noncardiac surgical patients were randomized aspirin or placebo and clonidine or placebo. Neuraxial block was defined as intraoperative spinal anaesthesia, or thoracic or lumbar epidural anaesthesia. Postoperative epidural analgesia was defined as postoperative epidural local anaesthetic and/or opioid administration. We used logistic regression with weighting using estimated propensity scores. RESULTS: Neuraxial block was not associated with the primary outcome [7.5% vs 6.5%; odds ratio (OR), 0.89; 95% CI (confidence interval), 0.73-1.08; P=0.24], death (1.0% vs 1.4%; OR, 0.84; 95% CI, 0.53-1.35; P=0.48), myocardial infarction (6.9% vs 5.5%; OR, 0.91; 95% CI, 0.74-1.12; P=0.36) or stroke (0.3% vs 0.4%; OR, 1.05; 95% CI, 0.44-2.49; P=0.91). Neuraxial block was associated with less clinically important hypotension (39% vs 46%; OR, 0.90; 95% CI, 0.81-1.00; P=0.04). Postoperative epidural analgesia was not associated with the primary outcome (11.8% vs 6.2%; OR, 1.48; 95% CI, 0.89-2.48; P=0.13), death (1.3% vs 0.8%; OR, 0.84; 95% CI, 0.35-1.99; P=0.68], myocardial infarction (11.0% vs 5.7%; OR, 1.53; 95% CI, 0.90-2.61; P=0.11], stroke (0.4% vs 0.4%; OR, 0.65; 95% CI, 0.18-2.32; P=0.50] or clinically important hypotension (63% vs 36%; OR, 1.40; 95% CI, 0.95-2.09; P=0.09). CONCLUSIONS: Neuraxial block and postoperative epidural analgesia were not associated with adverse cardiovascular outcomes among POISE-2 subjects.

[Prehospital non-invasive ventilation in Germany: results of a nationwide survey of ground-based emergency medical services]. / Prähospitale nichtinvasive Ventilation in der Bundesrepublik Deutschland: Ergebnisse einer bundesweiten Befragung bodengebundener Rettungsdienste.

BACKGROUND AND OBJECTIVES: Non-invasive ventilation (NIV) is an evidence-based treatment of acute respiratory failure and can be helpful to reduce morbidity and mortality. In Germany national S3 guidelines for inhospital use of NIV based on a large number of clinical trials were published in 2008; however, only limited data for prehospital non-invasive ventilation (pNIV) and hence no recommendations for prehospital use exist so far. AIM: In order to create a database for pNIV in Germany a nationwide survey was conducted to explore the status quo for the years 2005-2008 and to survey expected future developments including disposability, acceptance and frequency of pNIV. MATERIAL AND METHODS: A questionnaire on the use of pNIV was developed and distributed to 270 heads of medical emergency services in Germany. RESULTS: Of the 270 questionnaires distributed 142 could be evaluated (52 %). The pNIV was rated as a reasonable treatment option in 91 % of the respondents but was available in only 54 out of the 142 responding emergency medical services (38 %). Continuous positive airway pressure (98 %) and biphasic positive airway pressure (22 %) were the predominantly used ventilation modes. Indications for pNIV use were acute cardiogenic pulmonary edema (96 %), acute exacerbation of chronic obstructive pulmonary disease (89 %), asthma (32 %) and pneumonia (28 %). Adverse events were reported for panic (20 ± 17%) and non-threatening heart rhythm disorders (8 ± 5%), the rate of secondary intubation was low (reduction from 20 % to 10 %) and comparable to data from inhospital treatment. CONCLUSION: Prehospital NIV in Germany was used by only one third of all respondents by the end of 2008. Based on the clinical data a growing application for pNIV is expected. Controlled prehospital studies are needed to enunciate evidence-based recommendations for pNIV.

Ventilation with low tidal volumes during upper abdominal surgery does not improve postoperative lung function.

BACKGROUND: Prolonged postoperative decrease in lung function is common after major upper abdominal surgery. Evidence suggests that ventilation with low tidal volumes may limit the damage during mechanical ventilation. We compared postoperative lung function of patients undergoing upper abdominal surgery, mechanically ventilated with high or low tidal volumes. METHODS: This was a double-blind, prospective, randomized controlled clinical trial. One hundred and one patients (age ≥ 50 yr, ASA ≥ II, duration of surgery ≥ 3 h) were ventilated with: (i) high [12 ml kg(-1) predicted body weight (PBW)] or (ii) low (6 ml kg(-1) PBW) tidal volumes intraoperatively. The positive end-expiratory pressure was 5 cm H(2)O in both groups and breathing frequency adjusted to normocapnia. Time-weighted averages (TWAs) of forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV(1)) until 120 h after operation were compared (P<0.025 considered statistically significant). Secondary outcomes were oxygenation, respiratory and non-respiratory complications, length of stay and mortality. RESULTS: The mean (sd) values of TWAs of FVC and FEV(1) were similar in both groups: FVC: 6 ml group 1.8 (0.7) litre vs 12 ml group 1.6 (0.5) litre (P=0.12); FEV(1): 6 ml group 1.4 (0.5) litre vs 12 ml group 1.2 (0.4) litre (P=0.15). FVC and FEV(1) at any single time point and secondary outcomes did not differ significantly between groups. CONCLUSIONS: Prolonged impaired lung function after major abdominal surgery is not ameliorated by low tidal volume ventilation.

[Long-term treatment with oral ketamine. Case report of a female patient with therapy-resistant post-herpetic neuralgia]. / Langzeitbehandlung mit oralem Ketamin. Fallbericht einer Patientin mit therapieresistenter postzosterischer Neuralgie.

Postherpetic neuralgia can lead to therapy-resistant neuropathic pain. We report the case of a 74-year-old woman with postherpetic perineal neuralgia resistant to opioids and antiepileptic drugs who has been successfully treated with oral ketamine for 28 months. Pain scores were reduced by more than 50%, despite dose reduction of other analgetic drugs. Significant side effects have not yet been reported. Despite "off-label" use, ketamine is an important third line option in cases of therapy-resistant neuropathic pain.

[Difficult placement of a pulmonary artery catheter due to a persistent left vena cava superior]. / Erschwerte Anlage eines Pulmonaliskatheters durch eine persistierende linke V. cava superior.

The incidental detection of a persistent left vena cava superior during insertion of a pulmonary artery catheter in a patient with acute respiratory distress syndrome (ARDS) prior to extracorporeal membrane oxygenation (ECMO) therapy is reported. A persistent left vena cava superior is the most frequent thoracic malformation and can be associated with other malformations such as congenital heart disease. Therefore, further diagnostic evaluation is needed especially in pulmonary hypertension and ARDS. Anaesthesiologists should be aware of the specific aspects associated with a persistent left vena cava superior.

Nitrous oxide increases the incidence of bowel distension in patients undergoing elective colon resection.

BACKGROUND: Nitrous oxide rapidly inflates gas-filled spaces such as the intestines; but whether the resulting bowel distension is clinically important remains unclear. We therefore tested the hypothesis that nitrous oxide produces clinically important bowel distension. METHODS: Patients scheduled for colon resection were anesthetized with isoflurane and 35% oxygen and randomly assigned to 65% nitrous oxide (n = 175) or 65% nitrogen in air (n = 169). At the end of surgery, blinded surgeons rated the degree of bowel distension as none, mild, moderate, or severe. Patients reported pain, and nausea and vomiting (PONV) 2 h after surgery. Data are reported as means (SD). P < 0.05 was statistically significant. RESULTS: Morphometric and demographic data were similar in the groups. The duration of surgery was 3.0 (1.2) h in the nitrous oxide group and 3.4 (1.5) h in the air group (P = 0.017). Postoperative self-reported pain scores (visual analog scale, 0-100 mm) were greater in the nitrous oxide group (43 [30] mm) than in the air group (35 [31] mm, P = 0.018). Although the incidence of PONV was similar in the groups, VAS scores for nausea were significantly greater in the nitrous oxide group (P = 0.040). Moderate-to-severe bowel distension was observed in 23% of nitrous oxide patients, but in only 9% of patients in the air group (P < 0.001). The number-needed-to-harm for moderate or severe bowel distension from nitrous oxide was thus seven. CONCLUSIONS: Our results suggest that avoiding nitrous oxide administration during prolonged bowel operations will minimize bowel distension and possibly reduce postoperative pain related to it.