Misplaced and dislodged endotracheal tubes may be detected by the defibrillator during cardiopulmonary resuscitation

We present two cases of unrecognized endotracheal tube misplacements in out-of-hospital cardiopulmonary resuscitation recognized by the analysis of transthoracic impedance. In Case 1, ventilation-induced changes in transthoracic impedance disappeared after an intubation attempt corresponding to oesophageal intubation. This was clinically recognized after several minutes, the endotracheal tube was repositioned and alterations in transthoracic impedance resumed. In Case 2, the initial ventilation-induced signal change following endotracheal intubation weakened after a few minutes. At that time, the defibrillator gave vocal and visual feedback to the rescuers on ventilatory inactivity, a pharyngeal air leak was discovered simultaneously and the tube was found to be dislodged. Continuous monitoring of transthoracic impedance provided by the defibrillator during cardiopulmonary resuscitation may contribute to the early detection of an initially misplaced or later dislodged endotracheal tube.     

Feedback during cardiopulmonary resuscitation

PURPOSE OF REVIEW: Current cardiopulmonary resuscitation guidelines emphasize that providing high-quality basic life support is the single most important contribution to successful resuscitation. Efficiency of advanced cardiac life support depends on sufficient cardiopulmonary resuscitation performance leading to continuous bloodflow and oxygenation. Existing data show that the quality of cardiopulmonary resuscitation performance is poor. Feedback technologies claim to improve cardiopulmonary resuscitation quality by supporting rescuers in their efforts. RECENT FINDINGS: Rescuers regularly fail to achieve chest compressions at sufficient frequency and depth. Interruption of chest compression whilst the patient is in cardiac arrest results in reduced chances for successful defibrillation and survival. ECG interpretation in cardiac arrest challenges rescuers and results in nonindicated defibrillations. In several simulator studies and clinical trails cardiopulmonary resuscitation performance was improved by introducing feedback elements. It remains unclear, however, to what extent feedback is needed and useful. SUMMARY: Since effective basic life support is crucial for victims of cardiac arrest, recent findings that cardiopulmonary resuscitation quality provided by professionals fails to achieve recommended levels is not acceptable. Efforts need to be made in order to improve cardiopulmonary resuscitation quality and to support rescuers by real-time feedback. The technical elements of cardiopulmonary resuscitation feedback need to be carefully studied before being introduced into practice.     

Thrombolysis during cardiopulmonary resuscitation

Between 40 and 90 cardiopulmonary resuscitations are performed per 100,000 inhabitants each year in western industrialised nations. In 50-70% of these patients, either fulminant pulmonary embolism or acute myocardial infarction is the underlying cause of cardiac arrest. Based on this fact, thrombolysis may represent a new and effective causal therapeutic strategy in patients suffering from cardiac arrest due to acute myocardial infarction or fulminant pulmonary embolism. In the past, thrombolysis was contraindicated during cardiopulmonary resuscitation due to great fears of severe bleeding complications (resuscitation-mediated or lysis-induced intracerebral bleeding). For a long time, only clinical case reports or small clinical case series were reported in the literature, however, recently, the first clinical studies focusing on the safety and efficacy of thrombolytic therapy during out-of-hospital cardiopulmonary resuscitation have been published. Besides a specific therapeutic causal effect on pulmonary artery emboli and coronary artery thrombosis, experimental data strongly indicate that thrombolysis might also have an impact on cerebral microcirculatory reperfusion during and after cardiopulmonary resuscitation. This effect might be responsible for the exceptionally good neurological outcome observed in patients treated with thrombolytic agents during cardiopulmonary resuscitation and might be a result of the proven imbalance of the endogenous coagulation system in patients suffering from cardiac arrest. This coagulation imbalance is thought to be responsible for postresuscitation cerebral microcirculatory reperfusion disorders in patients after cardiac arrest and cardiopulmonary resuscitation. In summary, recent clinical and experimental data focusing on thrombolysis during cardiopulmonary resuscitation strongly indicate, that thrombolysis may represent a new and relatively safe therapeutic option during resuscitation after cardiac arrest due to acute myocardial infarction or fulminant pulmonary embolism. If the results of an international randomised, controlled clinical multicentre trial presently underway confirm the previous clinical findings, thrombolysis during cardiopulmonary resuscitation could become an important part of future cardiopulmonary resuscitation algorithms.     

Gastric rupture during cardiopulmonary resuscitation

Gastric rupture following ventilation during cardiopulmonary resuscitation is a rare occurrence. We report two cases of documented gastric rupture plus two additional cases in which the clinical diagnosis of pneumoperitoneum was made and gastric rupture was assumed to be the mechanism. Review of the literature reveals the lesser curvature of the stomach to be the common site of rupture. This complication emphasizes the necessities of correct positioning of the jaw with mouth-to-mouth ventilation and careful assessment of air entry and chest movement following endotracheal intubation.     

Thrombolytic therapy during cardiopulmonary resuscitation

Recently, efforts have been undertaken to investigate the effects of thrombolysis during cardiopulmonary resuscitation (CRP) in patients suffering from massive pulmonary embolism or acute myocardial infarction. In up to 70% of patients with cardiac arrest, one of these two diseases is the underlying cause of deterioration. Nevertheless, thrombolysis has not been conducted during CPR because of the fear of severe bleeding complications. However, an increasing number of clinical studies suggest that thrombolytic therapy during CPR can contribute to haemodynamic stabilisation and survival in patients with massive pulmonary embolism and acute myocardial infarction, when conventional CPR procedures have been performed unsuccessfully. Apart from the specific causal action of thrombolytic agents at the site of pulmonary emboli and coronary thrombosis, experimental data indicate that thrombolysis during CPR can improve microcirculatory reperfusion, which may be most important in the brain. In accordance with these data, marked activation of blood coagulation without adequate activation of endogenous fibrinolysis has been demonstrated early after cardiac arrest. In summary, thrombolysis during CPR is presently a treatment strategy that can be performed on an individual basis in patients with pulmonary embolism or acute myocardial infarction. It may become a routine measure if positive results of randomised, controlled clinical trials will be available in the future.     

Learning cardiopulmonary resuscitation using conventional external cardiac massage or active compression-decompression in simulated cardiopulmonary resuscitation]

OBJECTIVE: To compare medical students' simulated learning of two different techniques of cardiopulmonary resuscitation (CPR). One was conventional external cardiac massage (ECM) and the other was active compression-decompression (ACD-CPR). MATERIAL AND METHODS: The study group (group S) comprised 111 students enrolled in their fourth year of medical studies who had no prior experience of CPR. Group R, the control group, was made up of 32 medical residents in anesthesiology and post-anesthetic intensive care. Before the study, group S received 5 hours of theoretical classes on CPR and both groups saw a video explaining each technique just before performing the test. All subjects applied each method to an adult dummy for one minute. The variables evaluated were frequency of complete and effective thoracic compressions and the body weight of the resuscitator. RESULTS: Each group performed similarly using the two techniques in terms of frequency of total compressions achieved. For each technique, the number of effective compressions achieved by group S (49.4 +/- 22.9 with ECM and 42.5 +/- 20.7 with ACD-CPR) was significantly lower (p < 0.05) than the number attained by group R (71.2 +/- 18.6 with ECM and 58.8 +/- 12 with ACD-CPR). Group R's frequency of effective compressions was significantly higher (p < 0.05) with CPR than with ACD-CPR. Body weight had no influence on the number of total compressions or efficacy in group R, whereas lower body weight in group S was significantly related to lower frequency of effective compressions with ECM p < 0.05). Neither group achieved a frequency of 80 total compressions in one minute. CONCLUSIONS: With the present teaching method, the medical students' performance was poor for both types of CPR and was affected by body weight. The residents' performance was less effective with ACD-CPR, a technique that was new to them, than with conventional ECM, with which they were expert and on which body weight had no impact.     

Intraoperative use of automated external defibrillator.

We report on the anesthetic management of a patient with peripartum cardiomyopathy and frequent episodes of ventricular tachycardia, who underwent surgery for tracheal stenosis. Prior to this surgery, the patient had been implanted with an automatic implantable cardioverter-defibrillator (AICD), placed abdominally. In the operating room, the AICD was deactivated, and an automated external defibrillator (AED) was placed. Intraoperatively, the AED identified and treated the patient's ventricular tachycardia. Advantages of the AED in this hospital setting included rapid response to the cardiomyopathy, safe, hands-free operation, and minimal disruption of the surgical procedure. Safety concerns when using the AED are also detailed.     

Coronary perfusion pressure during cardiopulmonary resuscitation

Coronary perfusion pressure (CPP) generated during cardiopulmonary resuscitation (CPR) is a key component for successful resuscitation. Defined as the pressure gradient between the aorta and the right atrium during the ‘diastolic’ or decompression portion of chest compression-decompression, this gradient has been correlated with both myocardial blood flow generated with CPR and ultimately with resuscitation outcome. Several unique features of cardiac arrest physiology, specifically the loss of vascular auto-regulation, make this pressure gradient even more important and the principal determinant of myocardial blood flow during CPR. Additionally, the loss of the ability to selectively vasoconstrict and vasodilate before and after an intra-coronary lesion results in increased significance of any coronary obstruction (even lesions less than 50%) with profound compromising effects on distal flow. Although CPP has been measured in patients undergoing CPR it remains difficult to acquire, secondary to the time needed to insert the pressure-measuring catheters. Alternative non-invasive measures of coronary perfusion are needed. Expired end-tidal carbon dioxide has been one suggested possibility.     

The use of the laryngeal mask airway by nurses during cardiopulmonary resuscitation

A multicentre study was undertaken to assess the potential value of the laryngeal mask airway when inserted by ward nurses during resuscitation as a method of airway management, prior to the arrival of the Advanced Life Support Team with tracheal intubation capability. The nurses underwent a training programme agreed by all the participating hospitals and followed an identical protocol and data recording system. One hundred and thirty nurses were trained and 164 cases of cardiac arrest were studied. The laryngeal mask airway was inserted at the first attempt in 71% and at the second attempt in 26% of cases. Satisfactory chest expansion occurred in 86% of cases. The mean interval between cardiac arrest and laryngeal mask airway insertion was 2.4 min. Regurgitation of gastric contents occurred before airway insertion in 20 cases (12%), during the insertion in three cases (2%), but there was clinical evidence of pulmonary aspiration in only one patient, who survived to leave hospital. We conclude that the laryngeal mask airway offers advantages over other methods of airway and ventilation management, such as the bag-valve-mask or mouth-to-mouth methods that are currently used by ward nurses in resuscitating patients with cardiac arrest. In this study, the laryngeal mask airway was not being compared with the tracheal tube.     

The use of anti-arrhythmic agents in cardiopulmonary resuscitation

Cardiac arrest is a major cause of unexpected sudden death in adults. In the majority of cases an arrhythmia is the primary cause. A multitude of agents have been used in the treatment of ventricular fibrillation and asystole during cardiac arrest. At present there is no evidence to indicate that any of these agents ultimately improve the final outcome in humans. Prevention, competent basic life support and rapid defibrillation for patients in ventricular fibrillation remain the mainstays of treatment for cardiac arrest.     

Ambient oxygen concentrations during simulated cardiopulmonary resuscitation

Oxygen concentrations were measured at 12 points around a cardiopulmonary resuscitation practice mannequin following simulated ventilation with a self-inflating bag, a 'Waters' bag and a ventilator to determine whether increased oxygen concentrations may contribute to the risk of combustion from arcing defibrillator paddles. Ventilation was simulated using either a mask or via a tracheal tube fitted to the airway. The head of the mannequin rested upon a 10-cm-high pillow. Gas sampling took place after 5 min of ventilation with subsequent removal of the ventilatory device and placement on the pillow to the left of the mouth, with the tubing of the device removed to a point 1 m behind the mouth and with the device left connected to the tracheal tube. Gas was sampled after using all devices at oxygen flows of 10 lmin⁻¹ and 15 lmin⁻¹. Slightly increased oxygen concentrations were noted over the anterior chest after placement of all devices on the pillow at the higher flow. Concentrations of greater than 30% were measured in the left axilla after placement of all devices on the pillow at both flows. No increase in oxygen concentration was seen when the devices were either left connected to the tracheal tube or removed to a distance of 1 m. It would appear that leaving a patient connected to a ventilator poses no increase in risk of fire from ignition of combustible material in an oxygen-enriched atmosphere during defibrillation. Disconnecting any device which continues to discharge oxygen and leaving it on the pillow before defibrillation is dangerous.     

Use of vasopressor drugs during cardiopulmonary resuscitation

Epinephrine therapy during cardiopulmonary resuscitation (CPR) is associated with a variety of undesirable and potentially deleterious effects. Although several large clinical trials have been performed to study the role of epinephrine during cardiac arrest, no definite evidence of benefit has been shown. In summary, it can be said that long-term survival after CPR with epinephrine is disappointing, especially when considering out-of-hospital cardiac arrest.Vital organ blood flow during CPR and neurological recovery after CPR was significantly better in pigs treated with vasopressin compared to epinephrine. Furthermore, two clinical studies evaluating both out-of-hospital and in-hospital cardiac arrest patients found higher 24-hour survival rates in patients who were resuscitated with vasopressin compared to epinephrine. Scientists at the University in Innsbruck are currently co-ordinating a multicentre randomized clinical trial under the aegis of the European Resuscitation Council to study the effects of vasopressin versus epinephrine in out-of-hospital cardiac arrest patients. Results of the anticipated total of 1500 patients enrolled may be available in 2001, and may help to determine the role of vasopressin during CPR.     

Brain bioenergetics during cardiopulmonary resuscitation in dogs.

Cardiac arrest causes a rapid loss of cerebral adenosine triphosphate [corrected] (ATP) and a decrease in cerebral intracellular pH (pHi). Depending on the efficacy of cardiopulmonary resuscitation (CPR), cerebral blood flow levels (CBF) ranging from near zero to near normal have been reported experimentally. Using 31P magnetic resonance spectroscopy, the authors tested whether experimental CPR with normal levels of cerebral blood flow can rapidly restore cerebral ATP and pHi despite the progressive systemic acidemia associated with CPR. After 6 min of ventricular fibrillation in six dogs anesthetized with fentanyl and pentobarbital, ATP was reduced to undetectable concentrations and pHi decreased from 7.11 +/- 0.02 to 6.28 +/- 0.09 (+/- SE) as measured by 31P magnetic resonance spectroscopy. Application of cyclic chest compression by an inflatable vest placed around the thorax and infusion of epinephrine (40 micrograms/kg bolus plus 8 micrograms/kg/min, intravenously) maintained cerebral perfusion pressure greater than 70 mmHg for 50 min with the dog remaining in the magnet. Prearrest cerebral blood flows were generated. Cerebral pHi recovered to 7.03 +/- 0.03 by 35 min of CPR, whereas arterial pH decreased from 7.41 +/- 0.4 to 7.08 +/- 0.04 and cerebral venous pH decreased from 7.29 +/- 0.03 to 7.01 +/- 0.04. Cerebral ATP levels recovered to 86 +/- 7% (+/- SE) of prearrest concentration by 6 min of CPR. There was no further recovery of ATP, which remained significantly less than control. Therefore, in contrast to hyperemic reperfusion with spontaneous circulation and full ATP recovery, experimental CPR may not be able to restore ATP completely after 6 min of global ischemia despite restoration of CBF and brain pHi to prearrest levels.