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Description / Table of Contents: Abstract. Study objective. To follow up endothelin (ET), adrenocorticotropic hormone (ACTH), and cortisol levels in patients undergoing aortocoronary bypass grafting (CABG) and to determine whether these are extracted from plasma by the pulmonary circulation. Design. Convenience sample trial. Setting. University hospital. Patients. Eight male routine CABG patients without appreciable concomitant disease. Interventions. Patients were given anaesthesia in a strictly standardised manner using etomidate, flunitrazepam, fentanyl, and pancuronium. Nitroglycerin was administered prior to cardiopulmonary bypass (CPB) at 2 mg/h and dopamine as the only catecholamine starting from CPB weaning until the end of sampling at 3.5 – 5 µg/kg⋅min. Samples were drawn in rapid sequence from cannulated radial and a distal pulmonary arteries (Swan-Ganz catheter) at eight sampling times starting after induction of anaesthesia and catheter placement and finishing 22 h after the end of operation. Measurements and Results. ET levels were determined by an ET-1, 2, 3-sensitive radioimmunoassay (RIA), ACTH and cortisol by commercially available RIA kits. There was a significant (P=0.032, linear regression analysis) correlation between ET and cortisol from pulmonary arterial samples. ET was significantly (P=0.042, two-tailed Wilcoxon test) extracted by the pulmonary circulation after induction of anaesthesia. This pulmonary-systemic arterial difference nearly disappeared intraoperatively, but tended to be restored 22 h after the end of operation at an approximately twofold increased level. Conclusions. No interrelation between ET and the hypothalamic-pituitary-adrenal axis could be established by the ET, ACTH, and cortisol plasma levels. However, the significant correlation between perioperative ET and cortisol lends further support to the hypothesis of ET release by cortisol from vascular smooth-muscle cells. There is a net pulmonary clearance of ET in patients prior to CABG that is lost intra- and early postoperatively, but tends to be restored on the 1st day thereafter at an increased level.

Description / Table of Contents: Abstract In a recent German multicenter study, 25% of the patients who suffered a witnessed cardiac arrest outside the hospital were resuscitated successfully and were discharged from the hospital. Approximately 100000 people suffer a fatal cardiac arrest in Germany annually, which is about ten times more than deaths resulting from motor vehicle accidents. New devices and techniques for cardiopulmonary resuscitation (CPR) have been developed in order to enhance the efficacy of chest compressions during CPR. The purpose of the present article is to review mechanisms of blood flow during CPR, to discuss CPR devices and techniques (vest CPR, CPR with interposed abdominal compressions, active compression-decompression (ACD) CPR, phased chest and abdominal compression-decompression CPR, and to further evaluate results from subsequently published laboratory and clinical studies. Vest CPR performs chest compressions with a pneumatic pump, which is able to compress the entire thorax with great force while minimizing injury. This device was developed to achieve an optimal driving force of the thoracic-pump mechanism during CPR. After promising results in laboratory studies and further technical development, vest CPR increased coronary perfusion pressure (CPP) in a clinical study even after 45 min of unsuccessful advanced cardiac life support. Currently, this device is being evaluated in an international multicenter study in Europe and the United States. A vest for employment by the emergency medical service (EMS) is in preparation. Interposed abdominal compressions during relaxation of the chest may augment artificial blood flow. In some laboratory studies, this mechanism resulted, in part, in promising data, and in another did not achieve better survival rates in comparison with standard CPR. No benefit of abdominal compressions was shown in an investigation in an EMS, whereas in a clinical study patients who were treated with interposed abdominal compressions were more likely to survive and be discharged from the hospital. However, in a follow-up study of in-hospital patients with asystole or pulseless electrical activity, abdominal compressions resulted in higher 24-h survival, but not hospital discharge rate, when compared with standard CPR. In animal studies ACD CPR produced increased CPP, end-tidal carbon dioxide, minute ventilation, and short-term survival. Subsequently performed clinical studies confirmed the data from the laboratory investigations; however, the hemodynamic advantage of ACD CPR did not result in increased long-term survival and a better neurological outcome in both in- and out-of-hospital cardiac arrest patients. To date, the reason why better hemodynamic variables did not result in better outcomes is unknown. A combination of ACD CPR with interposed abdominal compressions raised cerebral blood flow by approximately 60%, but did not augment myocardial blood flow in comparison with standard CPR. Recently, a device was developed to administer phased chest and abdominal compression-decompression CPR; this technique has been tested in an animal study and showed significant hemodynamic advantages and better survival compared with standard CPR. Clinical investigations of this device are being performed. In summary, since the rediscovery of chest compressions more than 35 years ago, this intervention has not changed significantly. Objective data from laboratory and clinical studies such as systolic blood pressure, CPP, and the gold standard for the efficacy of CPR, long-term survival and neurorlogical outcome, will determine if a new device or technique can replace standard-CPR. Despite the new developments, it is mandatory to perform standard CPR correctly with a chest compression rate of 80–100/min and a depth of 38–50 mm.

Description / Table of Contents: Abstract. A strong consensus was reached for several changes in the guidelines for cardiopulmonary resuscitation (CPR) and emergency cardiac care (ECC) in the 1992 conference on CPR and ECC held by the Emergency Cardiac Care Committee of the American Heart Association. These new recommendations, together with differing recommendations of the European Resuscitation Council, are described. An unresponsive person with spontaneous respirations should be placed in the recovery position if no cervical trauma is suspected. Compared with endotracheal intubation, other airway-protecting devices such as combination esophageal-tracheal tubes are of minor acceptance. During ventilation, the time for filling the lungs is increased to 1.5 – 2 s to decrease the likelihood of gastric insufflation. Delivery of IV drugs can be enhanced by an IV flush of sodium chloride. In endotracheal drug administration, higher doses and drug dilution are recommended in infants and children up to 6 years of age, the value of intraosseous drug administration is emphasized. For pulseless adult victims, the intitial dosage of epinephrine of 1 mg I.V. remains unchanged. For repeat doses, high-dose epinephrine up to 0.1 mg/kg is classified as of uncertain but possible efficacy. For lidocaine, the recommended I.V. dosage is 1.5 mg/kg. Sodium bicarbonate and calcium are not routinely recommended for resuscitation. For atropine, the maximum dose is 0.04 mg/kg. If hypomagnesaemia is present in recurrent and refractory ventricular fibrillation, it should be corrected by administration of 1 to 2 mg magnesium sulfate I.V. Thrombolytic agents are classified as useful and effective in acute myocardial infarction and should be administered as early as possible. Glucose-containing fluids are discouraged for resuscitative efforts.

Description / Table of Contents: Abstract In a recently published German multicenter study, 25% of the patients with witnessed cardiac arrest outside the hospital were resuscitated successfully and discharged from the hospital. Approximately 100,000 people suffer a fatal cardiac arrest in Germany anually, which is approximately tenfold the number of deaths from motor vehicle accidents. Cardiopulmonary resuscitation (CPR) performed by bystanders is an important part of the chain of survival to minimize the time interval without artificial circulation and ventilation in a cardiac arrest victim. This is especially important in areas with long response times of the emergency medical service (EMS). Early examples of ventilation have been described throughout history. References to mouth-to-mouth ventilation (MTMV) are found in the Bible, in a description of the resuscitation of a coal miner in 1744, and in an experiment in 1796 demonstrating that exhaled gas was safe for breathing. In 1954, Elam and colleagues described artificial respiration with the exhaled gas of a rescuer using a mouth-to-mask ventilation method. The modern CPR era started with the combination of MTMV and chest compressions 35 years ago. However, the value of MTMV is currently under discussion because of a widespread fear of transmission of infectious diseases. Health-care professionals have stated in several studies that they may withhold MTMV when confronted with a cardiac arrest in a stranger. Although an infection with Mycobacterium tuberculosis is more likely than one with HIV via MTMV, the fear of the public is understandable. An expert committee of the American Heart Association stated that MTMV may be omitted in the initial phase of cardiac arrest, and considered recommending chest compressions only if the EMS will arrive rapidly. In paralyzed volunteers, however, ventilation induced by chest compressions was not able to provide sufficient gas exchange, especially when the airway was not protected. Laboratory investigations studying ventilation during CPR showed controlversial results; in one animal model of cardiac arrest with muscle paralysis, chest compressions were not sufficient for adequate gas exchange, but active compression-decompression CPR achieved reasonable ventilation. Animal models that prevented gasping during cardiac arrest required ventilation during CPR, whereas gasping animals seemed to be satisfactorily ventilated with chest compressions alone. The question whether spontaneous gasping after cardiac arrest in humans may be sufficient for oxygenation and carbon dioxide elimination is debatable, and remains unanswered at this time. When cardiac arrest is monitored, frequent coughing by the patient may maintain artificial ventilation and circulation for 30 s. The strategy to compress the thorax first and then maintain the airway and perform ventilation may only have an advantage for the first 30 s of CPR. Therefore, MTMV remains the therapy of choice to ventilate the victim of cardiac arrest. If a rescuer chooses to not perform MTMV, at least chest compressions should be administered. During ventilation with an unprotected airway, tidal volumes of 0.5 l instead 0.8–1.2 l may have an advantage. This strategy would decrease the inspiratory flow rate and, therefore, peak airway inflation pressure, which is associated with stomach inflation. Animal models indicate that lower esophageal sphincter pressure may decrease rapidly to 5 cm H2O during cardiac arrest, which may further increase the importance of a low peak airway pressure during ventilation with an unprotected airway. Gastric inflation may cause, besides regurgitation, aspiration, and pneumonia, an increased intragastric pressure, which may push up the diaphragm, decrease lung compliance, and induce a vicious circle of hypoventilation and stomach inflation. The value of cricoid pressure during ventilation with an unprotected airway has to be addressed and emphasized to all health-care professionals to avoid disastrous stomach inflation. Once the EMS arrives at the scene of cardiac arrest, rapid tracheal intubation and ventilation with oxygen remains the state-of-the-art therapy.