Emergency medicine -- new concepts and therapies improve outcome from cardiac arrest

According to scientific articles focusing on emergency medicine published in international journals in the past few months, early defibrillation by lay persons, thrombolysis during cardiopulmonary resuscitation (CPR) and treatment with mild therapeutic hypothermia have been identified as relevant, new and clinically important treatment options to improve outcome following cardiac arrest. Early defibrillation using automated external defibrillators by lay persons reduces the time interval between collapse and first attempts at defibrillation and thus improves outcome after prehospital cardiac arrest. Thrombolysis during CPR -- for which the results regarding safety and efficacy are available from nonrandomized trials -- can also be safely performed in case of pulseless electrical activity. Thrombolysis during cardiopulmonary resuscitation has, however, no significant effect in this subgroup of patients with pulseless electrical activity in whom outcome is poor if the drug is administered at the end of conventional CPR procedures. Mild therapeutic hypothermia, i. e., cooling of cardiac arrest victims to 32-34 degrees C central body temperature for 12-24 h following out-of-hospital cardiac arrest, markedly improves survival rate and neurological outcome. Since this has now been clearly documented in two randomized clinical trials, it can be assumed that this kind of intervention will be recommended and translated into clinical practice soon. In conclusion, new and clinically relevant methods to improve outcome following cardiac arrest are available and can now be widely used clinically.     

Heritable differences in respiratory drive and breathing pattern in mice during anaesthesia and emergence

Background. Postanaesthetic hypoxia and ischaemia can lead topostoperative morbidity and mortality. We studied the effectof isoflurane anaesthesia in two inbred mouse strains knownfor phenotypic differences in breathing pattern and respiratorydrive during carbon dioxide challenge and their first-generationoffspring (F₁). Methods. Using whole body plethysmography, we assessed respiratoryrate (RR) and pressure amplitude (Amp) in male B6 (high responderto hypercapnia), C3 (low responder), and F₁ mice at rest, duringanaesthesia with isoflurane, and during recovery from anaesthesia.At each time point, the magnitude and pattern of breathing weredetermined during hypercapnic challenge (FI_CO2 = 0.08).Data (mean (SD)) were analysed by generalized ANOVA with posthoc Bonferroni’s correction (P<0.05). Results. During isoflurane anaesthesia, strain differences betweenB6 and C3 mice in RR were obscured while differences in Amppersisted. In contrast to baseline RR responses to carbon dioxidewere significantly reduced at 0.5 MAC (increase in RR: 175 (33)bpm, 147 (44) bpm, 127 (33) bpm, for B6, C3, and F₁ strainsrespectively) and completely blocked at 1.5 MAC (change in RR:–3 (10) bpm, –2 (1) bpm, –4 (5) bpm, for B6,C3, and F₁ strains, respectively). During recovery, B6 miceshowed a significant increase in RR (77 (33) bpm; P<0.0001)as well as in Amp. This was not observed in either C3 (–22(31) bpm) or F₁ mice (23 (51) bpm). Conclusion. Isoflurane anaesthesia abolished the strain differencesin respiratory drive between B6, C3, and F₁ mice. However, duringrecovery from anaesthesia, significant strain variation in respiratorydrive reappeared and was more pronounced compared with pre-anaestheticlevels. These results suggested, that genetic differences mayhave minimal contribution to decreased respiratory drive duringanaesthesia, but may be a major risk factor for post-operativehypoventilation and the associated morbidity and mortality. Br J Anaesth 2003; 91: 541–5     

Postoperative upper airway obstruction after recovery of the train of four ratio of the adductor pollicis muscle from neuromuscular blockade

Anesthetics, and even minimal residual neuromuscular blockade, may lead to upper airway obstruction (UAO). In this study we assessed by spirometry in patients with a train-of-four (TOF) ratio >0.9 the incidence of UAO (i.e., the ratio of maximal expiratory flow and maximal inspiratory flow at 50% of vital capacity [MEF50/MIF50] >1) and determined if UAO is induced by neuromuscular blockade (defined by a forced vital capacity [FVC] fade, i.e., a decrease in values of FVC from the first to the second consecutive spirometric maneuver of > or =10%). Patients received propofol and opioids for anesthesia. Spirometry was performed by a series of 3 repetitive spirometric maneuvers: the first before induction (under midazolam premedication), the second after tracheal extubation (TOF ratio: 0.9 or more), and the third 30 min later. Immediately after tracheal extubation and 30 min later, 48 and 6 of 130 patients, respectively, were not able to perform spirometry appropriately because of sedation. The incidence of UAO increased significantly (P < 0.01) from 82 of 130 patients (63%) at preinduction baseline to 70 of 82 patients (85%) after extubation, and subsequently decreased within 30 min to values observed at baseline (80 of 124 patients, 65%). The mean maximal expiratory flow and maximal inspiratory flow at 50% of vital capacity ratio after tracheal extubation was significantly increased from baseline (by 20%; 1.39 +/- 1.01 versus 1.73 +/- 1.02; P < 0.01), and subsequently decreased significantly to values observed at baseline (1.49 +/- 0.93). A statistically significant FVC fade was not present, and a FVC fade of > or =10% was observed in only 2 patients after extubation. Thus, recovery of the TOF ratio to 0.9 predicts with high probability an absence of neuromuscular blocking drug-induced UAO, but outliers, i.e., persistent effects of neuromuscular blockade on upper airway integrity despite recovery of the TOF ratio, may still occur.     

Therapie des nichtmetastasierten Prostatakarzinoms

Background

Patients with nonmetastatic prostate cancer face a complex treatment decision. To support them with personalized information, a variety of interactive computerized decision aids have been developed in Anglo-Saxon countries. Our goal was to identify relevant decision aids and investigate their didactic strengths and limitations.

Materials and methods

We included decision aids that derived individualized content from personal and clinical data provided by the patient. By conducting a systematic literature and internet research through November 2013 supplemented by expert interviews, we identified 10 decision aids of which 6 had been investigated scientifically. We compared their individual characteristics as well as the design and results of the evaluation studies.

Results

The decision aids present two to seven therapy choices, whereby radical prostatectomy and percutaneous radiotherapy are always included. Number and type of parameters provided by the patient also vary considerably. Two decision aids derive a therapeutic recommendation from the patient’s input. Evaluation studies showed higher disease-related knowledge and greater confidence in the treatment decision after using one of six decision aids. Satisfaction with the decision aid was predominantly high.

Conclusions

Currently personalized patient decision aids for treatment of nonmetastatic prostate cancer are only available in English. These tools can facilitate the shared decision making process for patients and physicians. Therefore, comparable decision aids should be developed in German.     

Pulmonary sympathetic denervation does not increase airway resistance in patients with chronic obstructive pulmonary disease (COPD)

Whether or not neural blockade of pulmonary sympathetic innervation is of relevance for airway resistance in patients with chronic obstructive pulmonary disease (COPD) is unknown. Accordingly we evaluated airway resistance during sympathetic blockade by high thoracic epidural anaesthesia in patients with COPD. Before and 45 min after thoracic epidural injection of bupivacaine 0.75% (6–8 ml; n=10) total respiratory resistance (oscillometry, R_os), vital capacity (VC), forced expiratory vital capacity in 1 s (FEV₁, [% VC]), functional residual capacity (FRC; helium dilution method), and arterial blood gases were measured. Three additional patients received bupivacaine intravenously (1.2 mg . min^-1 for 45 min), another three received saline epidurally. Sensory blockade covered segment C₅ through T₈. As an indicator of widespread sympathetic blockade including the lungs, skin temperature increased significantly on thumb and little toe. Despite pulmonary sympathetic denervation R_os, FEV₁, and FRC remained unchanged, while VC decreased slightly, probably due to intercostal muscle blockade. Blood gases remained constant. Neither intravenous bupivacaine nor epidural saline evoked directional changes. Since, in contrast to β-adre-noceptor blockade, pulmonary sympathetic denervation did not increase airway resistance in patients with COPD, neural sympathetic blockade seems to be of no relevance for airway resistance in these patients.     

31-year-old injection drug user with massive skin necrosis and shock

Massive tissue necrosis and septic shock have recently been reported in a series of injection drug users in Scotland, England and Ireland. We report the first case outside the UK meeting the criteria for this new entity (septic shock without fever in an injection drug user, local and systemic inflammation, rhabdomyolysis and tissue necrosis at the injection site). Following surgical treatment and antibiotic treatment, the patient was cured and is currently well.     

Risks and benefits of invasive epilepsy surgery workup with implanted subdural and depth electrodes

Purpose: In patients with pharmacoresistant focal‐onset seizures, invasive presurgical workup can identify epilepsy surgery options when noninvasive workup has failed. Yet, the potential benefit must be balanced with procedure‐related risks. This study examines risks associated with the implantation of subdural strip and grid, and intracerebral depth electrodes. Benefit of invasive monitoring is measured by seizure outcomes. Diagnostic procedures made possible by electrode implantation are described. Methods: Retrospective evaluation of invasive workups in 242 epilepsy surgery candidates and additional 18 patients with primary brain tumors implanted for mapping only. Complications are scaled in five grades of severity. A regression analysis identifies risk factors for complications. Outcome is classified according to Engel’s classification. Key Findings: Complications of any type were documented in 23% of patients, and complications requiring surgical revision in 9%. We did not find permanent morbidity or mortality. Major risk factor for complications was the implantation of grids and the implantation of electrode assemblies comprising strip and grid electrodes. Depth electrodes were significantly correlated with a lower risk. Tumors were not correlated with higher complication rates. Chronic invasive monitoring of 3–40 days allowed seizure detection in 99.2% of patients with epilepsy and additional extensive mapping procedures. Patients with epilepsy with follow‐up >24 months (n = 165) had an Engel class 1a outcome in 49.7% if epilepsy surgery was performed, but only 6.3% when surgery was rejected. Significance: The benefit of chronic invasive workup outweighs its risks, but complexity of implantations should be kept to a minimum.     

Ipratropium Decreases Airway Size in Dogs by Preferential M sub 2 Muscarinic Receptor Blockade In Vivo

Background: Two major groups of drugs are available to prevent bronchoconstriction: beta-agonists and muscarinic blocking agents. Ipratropium is the most commonly used anti-cholinergic agent to treat chronic obstructive pulmonary disease. The authors studied anti-muscarinic agents to determine if they are as effective bronchodilators as beta-adrenergic agents and if not to identify the mechanism of their reduced effectiveness.

Methods: Six anesthetized dogs were studied using high-resolution computed tomography to measure changes in the cross-sectional area of conducting airways induced by cumulative doses of ipratropium with and without gallamine, a selective M2 muscarinic receptor blocker, and after metaproterenol.

Results: Metaproterenol dilated the airways and ipratropium constricted the airways. Ipratropium in concentrations of 0.01 and 0.1 mg/ml constricted the airways to 22 +/- 2% and 20 +/- 3% of control, respectively (P < 0.01), whereas larger concentrations caused bronchodilation. After complete blockade of the M2 receptors by pretreatment with intravenous gallamine, the bronchoconstrictor effect of ipratropium was abolished, and ipratropium dilated the airways by 16 +/- 8% and 27 +/- 10% of pre-gallamine baseline after doses of 0.01 and 0.1 mg/ml, respectively (P < 0.01).     

Different mechanisms of atelectasis formation require different treatment strategies

Several strategies have been developed to treat atelectasis, including positive end-expiratory pressure and deep inspirations. However, in some patients these recruitment strategies fail to improve lung function. Therefore, the authors studied whether recruitment maneuvers could resolve atelectasis following either passive airway closure or active bronchconstriction. Aerated lung areas were measured in 5 dogs at baseline, and after airway closure with either a bronchial blocker, or administration of methacholine, followed by deep inspiration. Finally, bronchoconstriction was reversed pharmacologically. Bronchial occlusion reduced aerated lung areas, which were reopened by deep inspirations. Following methacholine, aerated lung areas were also significantly reduced; however, deep inspirations had no significant effect. Passive atelectasis was easily resolved by deep inspirations. In contrast, active airway constriction that leads to atelectasis could not be overcome with recruitment maneuvers.