External Chest Research Articles

Advanced cardiac life support before and after tracheal intubation—direct measurements of quality

Tracheal intubation should improve the quality of cardiopulmonary resuscitation (CPR) by enabling adequate ventilation without pauses in external chest compressions. Out-of-hospital cardiac arrests of all causes were sampled in this non-randomized, observational study of advanced cardiac life support in three ambulance services (Akershus, London and Stockholm). Prototype defibrillators (Heartstart 4000SP, Philips Medical Systems, Andover, MA, USA and Laerdal Medical AS, Stavanger, Norway) registered all chest compressions via an extra chest pad with an accelerometer mounted over the lower part of sternum and ventilations from changes in transthoracic impedance between the standard defibrillator pads. The quality of CPR was analyzed off-line for 119 episodes. Numbers and differences are given as mean +/- S.D. and differences as mean and 95% confidence intervals. Chest compressions were not given in cardiac arrest for 61 +/- 20% of the time before intubation compared to 41 +/- 18% after intubation (difference: 20% (16-24%)). Compressions and ventilations per minute increased from 47 +/- 25 to 71 +/- 23 (difference: 24 (19, 29)) and 5.6 +/- 3.7 to 14 +/- 5.0 (difference: 8.7 (7.6, 9.8)) respectively. Four cases of unrecognized oesophageal intubation (3%) were suspected from the disappearance of ventilation induced changes in thoracic impedance after intubation. The quality of CPR improved after tracheal intubation, but the fraction of time without blood flow was still high and not according to international guidelines. On-line analysis of thoracic impedance might be a practicable aid to avoid unrecognized oesophageal intubation, but this area needs further research.

Resuscitation from adrenaline resistant electro-mechanical dissociation facilitated by levosimendan in a young man with idiopathic dilated cardiomyopathy

A 32-year-old man with severe congestive heart failure due to idiopathic cardiomyopathy developed ventricular tachycardia followed by electro-mechanical dissociation. High doses of conventional inotropic medications failed to restore haemodynamics. The additional infusion of levosimendan in conjunction with external chest compressions for 2.5 h restored haemodynamics, followed by complete recovery, including normal neurological function. The anti-stunning properties of levosimendan probably attenuated post-ischaemic myocardial dysfunction and helped to restore normal cardiac output.

On using an adaptive neural network to predict lung tumor motion during respiration for radiotherapy applications

In this study we address the problem of predicting the position of a moving lung tumor during respiration on the basis of external breathing signals--a technique used for beam gating, tracking, and other dynamic motion management techniques in radiation therapy. We demonstrate the use of neural network filters to correlate tumor position with external surrogate markers while simultaneously predicting the motion ahead in time, for situations in which neither the breathing pattern nor the correlation between moving anatomical elements is constant in time. One pancreatic cancer patient and two lung cancer patients with mid/upper lobe tumors were fluoroscopically imaged to observe tumor motion synchronously with the movement of external chest markers during free breathing. The external marker position was provided as input to a feed-forward neural network that correlated the marker and tumor movement to predict the tumor position up to 800 ms in advance. The predicted tumor position was compared to its observed position to establish the accuracy with which the filter could dynamically track tumor motion under nonstationary conditions. These results were compared to simplified linear versions of the filter. The two lung cancer patients exhibited complex respiratory behavior in which the correlation between surrogate marker and tumor position changed with each cycle of breathing. By automatically and continuously adjusting its parameters to the observations, the neural network achieved better tracking accuracy than the fixed and adaptive linear filters. Variability and instability in human respiration complicate the task of predicting tumor position from surrogate breathing signals. Our results show that adaptive signal-processing filters can provide more accurate tumor position estimates than simpler stationary filters when presented with nonstationary breathing motion.

Late recurrence of invasive cervical cancer: Twenty years’ experience in a single cancer institute

To estimate the characteristics of, and prognosis for, late recurrence of cervical cancer. Between 1977 and 1996, of 1721 patients with invasive cervical cancer, 1157 survived more than 5 years. Twenty-eight patients whose cancer recurred after a disease-free interval of 5 years were retrospectively investigated. For 22 patients the cancer recurred after less than 10 years, for five patients it recurred between 10 and 20 years after the original occurrence, and in one patient the cancer recurred after more than 20 years. The histologic subtypes included 20 squamous cell carcinomas and eight adenocarcinomas. The initial therapies were surgery alone (on one patient), surgery and adjuvant radiotherapy (on 20 of the patients) and radiotherapy alone (on seven of the patients). Recurrence was initially diagnosed by internal or external examination (11 patients), chest X-ray (six patients) and computed tomography (11 patients). Rates of lymphogenous metastases were 19% of patients with primary surgery and 57% of patients without primary surgery, while those of hematogenous metastases were 48% of patients with primary surgery and none of patients without primary surgery (P = 0.023). The overall survival rate after recurrence was 50.5% after 2 years and 22.3% after 5 years, respectively. Four of the patients survived for more than 3 years without evidence of disease; these patients all had recurrence outside the irradiated field and achieved complete remission with radiotherapy. Late recurrence of cervical cancer was frequently observed in patients with initial treatment, including radiotherapy. Some had very long disease-free intervals, but many were diagnosed by ordinary internal or external examination or chest X-ray. Patients with primary surgery experienced recurrence less frequently in the case of lymph node metastasis than was the case for hematogenous metastasis. Radiotherapy was effective and improved prognosis, especially for recurrence of cancer outside the irradiated field.

A case of hypothermic cardiac arrest treated with an external chest compression device (LUCAS) during transport to re-warming

The recommended treatment for severe hypothermia with circulatory collapse is re-warming using cardiopulmonary by-pass. This may require transporting a patient to hospital with on-going cardiopulmonary resuscitation (CPR). Manual CPR during patient transport may result in sub-optimal chest compressions and can be a hazard for the ambulance crew. We report a case of a patient with a core temperature of 22.2 °C and crew-witnessed cardiac arrest due to hypothermia. After unsuccessful initial resuscitation he was transported to hospital for re-warming with cardiopulmonary by-pass. CPR was continued during transport using a mechanical active compression–decompression device (the LUCAS-device). During cardiopulmonary by-pass ROSC was achieved after 90 min of cardiac arrest. The patient recovered with a cerebral performance category of 3. Using a mechanical device for chest compressions during transport of a hypothermic patient with on-going CPR is feasible, effective and safe.

Effects of an impedance threshold valve upon hemodynamics in Standard CPR: Studies in a refined computational model

An impedance threshold valve (ITV) is a new airway adjunct for resuscitation that permits generation of a small vacuum in the chest during the recoil phase of chest compression. Objectives: To explore in detail the expected magnitude and the hemodynamic mechanisms of circulatory augmentation by an ITV in Standard CPR. Method: A 14-compartment mathematical model of the human cardiopulmonary system—upgraded to include applied chest compression force, elastic recoil of the chest wall, anatomic details of the heart and lungs, and the biomechanics of mediastinal compression—is exercised to explore the conditions required for circulatory augmentation by an ITV during various modes of CPR. Results: The ITV augments systemic perfusion pressure by about 5 mmHg compared to any particular baseline perfusion pressure without the ITV. When baseline perfusion is low, owing to either diminished chest compression force, the existence of a thoracic pump mechanism of blood flow, or the presence of an effective compression threshold, then the relative improvement produced by an ITV is significant. With an ITV the heart expands into soft pericardiac tissue, which makes the heart easier to compress. Conclusions: An ITV can augment perfusion during CPR. The observed effectiveness of ITVs in the laboratory and in the clinic suggests a thoracic pump mechanism for Standard CPR, and perhaps also an effective compression threshold that must be exceeded to generate blood flow by external chest compression.

Influence of different breathing maneuvers on internal and external organ motion: Use of fiducial markers in dynamic MRI

To investigate, with dynamic magnetic resonance imaging (dMRI) and a fiducial marker, the influence of different breathing maneuvers on internal organ and external chest wall motion. Lung and chest wall motion of 16 healthy subjects (13 male, 3 female) were examined with real-time trueFISP (true fast imaging with steady-state precession) dMRI and a small inductively coupled marker coil on either the abdomen or thorax. Three different breathing maneuvers were performed (predominantly "abdominal breathing," "thoracic breathing," and unspecific "normal breathing"). The craniocaudal (CC), anteroposterior (AP), and mediolateral (ML) lung distances were correlated (linear regression coefficient) with marker coil position during forced and quiet breathing. Differences of the CC distance between maximum forced inspiration and expiration were significant between abdominal and thoracic breathing (p < 0.05). The correlation between CC distance and coil position was best for forced abdominal breathing and a marker coil in the abdominal position (r = 0.89 +/- 0.04); for AP and ML distance, forced thoracic breathing and a coil in the thoracic position was best (r = 0.84 +/- 0.03 and 0.82 +/- 0.03, respectively). In quiet breathing, a lower correlation was found. A fiducial marker coil external to the thorax in combination with dMRI is a new technique to yield quantitative information on the correlation of internal organ and external chest wall motion. Correlations are highly dependent on the breathing maneuver.

Psychiatric Symptoms of Adolescents with Physical Complaints Admitted to an Adolescence Unit

The aim of this study was to evaluate the psychiatric symptoms among adolescents who were seen in the outpatient clinic for their physical complaints. Two hundred and ninety adolescent outpatients (154 males and 136 females) between 13 and 17 years of age (mean 14.3+/-1.2) are included in this study. Patients with known psychiatric disorders, mental retardation, organic brain diseases, or chronic organic problems were excluded. The Brief Symptom Inventory, which measures the psychiatric symptoms under the categories of anxiety, depression, negative self, somatization, and hostility, was given to all subjects. Symptoms of urinary and cardiovascular systems were related to hostility. Patients with obesity, hirsutism, problems of external genitalia, enuresis nocturna, abdominal pain, chest pain, and lack of weight gain showed psychiatric symptoms at pathological levels. Hostility symptom was found to be high in all groups.

Cardiopulmonary resuscitation development

As the popularity of chloroform as an anesthetic agent grew, deaths associated with its use began to be reported. It was found that this was due to respiratory and cardiac arrest. Cardiopulmonary resuscitation (CPR) is a method for restoring the circulation and respiration in a patient who has suffered cardiopulmonary arrest, often the sequel to a heart attack. The method involves forcible rhythmic chest compression to squeeze blood out of the arrested heart and mouth-to-mouth inflation of the lungs (with the nose clamped with the index finger and thumb). The method derived separately from two sources: 1) artificial respiration and 2) external chest compression to expel blood from the heart. This paper discusses studies of resuscitation associated with chloroform anesthesia.

Open indirect cardiac massage in neonate

Open, direct cardiac massage (OCM), as a technique of resuscitation has not been very inspiring due to its various limitations. We report a case of resuscitation where open 'indirect' cardiac massage was used to resuscitate a neonate successfully. A 24 hr old neonate with multiple gastrointestinal anomalies presented for emergency laparotomy. Intraoperatively she suffered a cardiac arrest. External chest compressions (ECC) failed to produce detectable circulation and surgeons were asked to initiate direct cardiac compressions. They could palpate and successfully compress the heart without the need to split the diaphragm. This 'infra-diaphragmatic' approach resulted in adequate circulation and subsequent uncomplicated recovery.

Increased cortical cerebral blood flow with LUCAS; a new device for mechanical chest compressions compared to standard external compressions during experimental cardiopulmonary resuscitation

Objective: LUCAS is a new device for mechanical compression and decompression of the chest during cardiopulmonary resuscitation (CPR). The aim of this study was to compare the efficacy of this new device with standard manual external chest compressions using cerebral cortical blood flow, cerebral oxygen extraction, and end-tidal CO 2 for indirect measurement of cardiac output. Drug therapy, with adrenaline (epinephrine) was eliminated in order to evaluate the effects of chest compressions alone. Methods: Ventricular fibrillation (VF) was induced in 14 anaesthetized pigs. After 8 min non-intervention interval, the animals were randomized into two groups. One group received external chest compressions using a new mechanical device, LUCAS. The other group received standard manual external chest compressions. The compression rate was 100 min −1 and mechanical ventilation was resumed with 100% oxygen during CPR in both groups. No adrenaline was given. After 15 min of CPR, external defibrillatory shocks were applied to achieve restoration of spontaneous circulation (ROSC). Cortical cerebral blood flow was measured continuously using Laser-Doppler flowmetry. End-tidal CO 2 was measured using mainstream capnography. Results: During CPR, the cortical cerebral blood flow was significantly higher in the group treated with LUCAS ( p = 0.041). There was no difference in oxygen extraction between the groups. End-tidal CO 2, an indirect measurement of the achieved cardiac output during CPR, was significantly higher in the group treated with the LUCAS device ( p = 0.009). Restoration of spontaneous circulation was achieved in two animals, one from each group. Conclusions: Chest compressions with the LUCAS device during experimental cardiopulmonary resuscitation resulted in higher cerebral blood flow and cardiac output than standard manual external chest compressions. These results strongly support prospective randomised studies in patients to evaluate this new device.

Details of the initial management of cardiac arrest occurring in the workplace in a French urban area

Introduction: Our goal was to evaluate the details and management of cardiac arrest (CA) occurring in the working environment. Materials and methods: We conducted a 10-year retrospective study based on the medical records of the Garches mobile intensive care unit. CA occurring in the workplace (“Inside W.” group) was matched with two CA outside the workplace (“Outside W.” group), with regard to sex, age and year of occurrence. The Chain of Survival and prognosis factors were analysed in a bi-multivariate analysis. Results: From 1993 to 2002, 72 CA were included in the “Inside W.” group, with 79% arising from suspected cardiac aetiology (there was a similar proportion in the “Outside W.” group). Some variables in the cardiac aetiology patients were higher in the “Inside W.” group compared to the “Outside W.” group ( P < 0.05): early external chest compression [(ECC), 37%, n = 20 versus 16%, n = 16)] and ventricular fibrillation as initial recorded rhythm (40%, n = 33 versus 16%, n = 16). The proportion of use of automated external defibrillator (AED) was similar in the two groups. The workplace was not associated with a better outcome, with 9% patients discharged alive compared to 4% n = 6, P > 0.05. Early ECC and defibrillation attempted with an AED were associated with patients discharged alive from the intensive care unit in a multivariate analysis ( P < 0.05), but not the workplace and cardiac aetiology. Conclusion: Although our study did not support that concept that the workplace was a safer place, there was a better chain of survival for CA applied within workplace settings. Basic Life Support teaching and installation of AEDs could be helpful, though further cost-effectiveness studies are needed.

Kouwenhoven, Jude and Knickerbocker: The introduction of defibrillation and external chest compressions into modern resuscitation

Kouwenhoven, Jude and Knickerbocker: The introduction of defibrillation and external chest compressions into modern resuscitation

Two-rescuer CPR results in hyperventilation in the ventilating rescuer

The “Guidelines 2000 for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care – International Consensus on Science” recommend a tidal ventilation volume of 10 ml/kg body-weight without the use of supplemental oxygen during two-rescuer adult cardiopulmonary resuscitation (CPR). This relates to a ventilation volume of about 6.4 l/min. Additionally, the first aid provider ventilating the victim will breathe for him/herself during the external chest compression period adding another 3.2 l/min of ventilation. Finally, a deep breath is recommended before each ventilation to increase the end-expiratory oxygen concentration of the air exhaled. To investigate the effects of these recommendations, 20 healthy volunteers were asked to perform two-rescuer CPR in a lung model connected to a BLS-manikin. End-tidal carbon dioxide, oxygen saturation, and heart rate were recorded continuously. Capillary blood gas samples were collected and non-invasive blood pressure was recorded prior to the start of external chest compressions and immediately after the end of each measurment period. Furthermore, hyperventilation related symptoms reported by the volunteers were also recorded. The data reveal a significant decrease in capillary and end-tidal carbon dioxide pressure in the volunteers ( P < 0.001). Additionally, in 75% of test persons multiple hyperventilation associated symptoms occurred. Ventilation during two-rescuer CPR performed according to the Guidelines 2000 may cause injury to the health of first aid providers. To minimize hyperventilation, both rescuers should exchange their positions at intervals of 3–5 min. These data challenge the recommendation to take a deep breath prior to each ventilation.

Cardiopulmonary Resuscitation Review: Critical Role of Chest Compressions

50-year-old man suddenly collapsed while standing in the waiting area of a local hospital. A physician walking by promptly determined, by the absence of carotid pulses, that cardiac activity had ceased. He then quickly removed a Swiss Army knife that he kept in his trouser pocket, made several chest wall precordial incisions to expose the heart, which he found to be in standstill, and initiated hand compression cardiac massage (all within 3 minutes of the event). Cardiac contractions promptly returned and the patient started to breathe. The patient was immediately taken to surgery and the chest wounds were cleansed and repaired. Subsequent chest wall and pericardial infections were treated using drains and intensive parenteral antibiotics: the patient recovered and was discharged 3 weeks after the event. This was the state of cardiac resuscitative measures in the “1950s” when it was not uncommon for physicians to carry folding knives to be used in sudden death emergencies. It was not until 1959 that Kouwenhoven and Jude 1 first reported on the success of external chest compression as a procedure that could safely and effectively massage the heart and reverse sudden cardiac death. This was the stimulus for the birth of modern cardiopulmonary resuscitation (CPR).

CPREzy™: an evaluation during simulated cardiac arrest on a hospital bed

CPREzy is a new adjunct designed to improve the application of manual external chest compressions (ECC) during cardiopulmonary resuscitation (CPR). The aim of this study was to determine the effect of using the CPREzy device compared to standard CPR during the simulated resuscitation of a patient on a hospital bed. Twenty medical student volunteers were randomised using a cross over trial design to perform 3 min of continuous ECC using CPREzy and standard CPR. There was a significant improvement in ECC depth with CPREzy compared to standard CPR 42.9 (4.4) mm versus 34.2 (7.6): mm, P = 0.001; 95% CI d.f. 4.4-12.9 mm. This translated to a reduction in the percentage of shallow compressions (<38 mm) with CPREzy 16 (23)% compared to standard CPR 59 (44)%, P = 0.003. There was a small increase in the percentage of compression regarded excessive (>51 mm): CPREzy 6.5 (19)% versus standard CPR 0 (0.1)%. P = 0.012). There was no difference in compression rate or duty cycle between techniques. Equal numbers of participants (40% in each group) performed one of more incorrectly placed chest compression. However the total number of incorrect compressions was higher for the CPREzy group (26% versus 3.9% standard CPR, P < 0.001). This was due to a higher number of low compressions (26% of total compressions for CPREzy versus 1% for standard CPR, P < 0.001). In conclusion, CPREzy was associated with significant improvements in ECC performance. Further animal and clinical studies are required to validate this finding in vivo and to see if it translates to an improvement in outcome in human victims of cardiac arrest.

Chest wall injuries following cardiopulmonary resuscitation

The forensic records were reviewed of 1823 deaths referred to Edinburgh City Mortuary for autopsy over a 15-month period, 2000-2001; 499 cases (343 males, 156 females) that received CPR prior to death were studied. Rib fractures were found in 29%, sternal fracture in 14%, and 11% of cases showed external chest wall bruising or abrasion. More females sustained rib fractures than males (37% versus 26%; P <0.05). There was no significant gender difference for sternal fracture (females 17%, males 12%; P=0.051). The incidence of rib fractures increased with age (P <0.001). There was no significant difference in the number of left or right ribs fractured (P=0.631). This study incorporates all cases of in and out-of-hospital CPR and does not discriminate for the CPR provider or technique employed, therefore, providing a current and representative overview of the incidence of rib and sternal fractures in non-survivors of CPR.

Thoracic Gas Volume Measurements in Paralyzed Mice

We have previously measured thoracic gas volume (VTG) in spontaneously breathing mice using a whole body plethysmograph and have now extended our technique to allow for V(TG) measurements during paralysis. BALB/c mice were anesthetized and placed in a body-box and ventilated via a tracheostomy cannula through the box wall. Box pressure (Pb) and tracheal pressure (Pao) were measured during spontaneous breathing, and again after paralysis while mechanically compressing the chest. V(TG) was much larger after paralysis (0.49+/-0.06 ml, positive end-expiratory pressure = 2 cmH2O) when compared with spontaneous breathing (0.31+/-0.01 ml). External chest compression produced looping in the plots of Pb versus Pao that was attributable to gradual changes in Pb upon release of the mechanical chest compression and had the character of thermal transients. Under the assumption that the rate of heating of the air in the chamber was proportional to the pressure applied to the animal's chest, and that any increase in air temperature was dissipated by heat absorption by the chamber walls, we developed an algorithm that corrected for the thermal events. This yielded similar results for V(TG) (0.30+/-0.02 ml) as obtained during spontaneous efforts. Our method may prove particularly useful when paralysis is required for the precise measurement of lung mechanics.

Effect of standard cardiopulmonary resuscitation on cerebral blood flow and coronary perfusion pressure in the canine model of simulated ventricular tachycardia

Study objectives: The purpose of this study is to evaluate the hemodynamic effects of external chest compression in state of the heart's beating. Methods: Ten mongrel dogs were used in this study. Ventricular tachycardia (VT) was simulated by using a rapid ventricular pacing, and ventricular rate was adjusted and maintained at the rate necessary to achieve a 50-mm Hg decrease in the baseline systolic aortic pressure. External chest compression (ECC) was initiated after 4 minutes of simulated VT and was continued for 4 minutes. Hemodynamic measurements, including the systolic and the diastolic aortic pressure, the right atrial pressure, the carotid blood flow, and the end-tidal CO 2 tension, were done at baseline during simulated VT and during simulated VT with ECC (VT+ECC). Results: The systolic aortic pressure, the diastolic aortic pressure, and the mean right atrial pressure were higher during VT+ECC than during VT (99±12 versus 92±8 mm Hg, P =.157, 59±8 versus 55±12 mm Hg, P =.140, and 23±8 versus 8±2 mm Hg, P =.000, respectively). The carotid blood flow was higher during VT+ECC than during VT (273±203 versus 136±76 mL/minute, P =.011). The calculated coronary perfusion pressure was lower during VT+ECC than during VT (26±8 versus 40±9 mm Hg, P =.000). The end-tidal CO 2 tension was not different between VT+ECC and VT. Conclusion: In the canine model of simulated VT, ECC had a contradictory hemodynamic effect, including an increase in the cerebral blood flow and a decrease in the coronary perfusion pressure.

A new method for inducing hypothermia during cardiac arrest

It has been shown that hypothermia induced after successful resuscitation of comatose survivors of ventricular fibrillation cardiac arrest improves survival and neurologic function. Recent studies also suggest that earlier induction of hypothermia may yield even more improvement. We sought to determine if a new pump system, in addition to vigorous external chest compression, could rapidly induce hypothermia during cardiopulmonary resuscitation in a porcine model of cardiac arrest. Nine pigs (25-37 kg) were instrumented with micromanometers and thermocouple probes. Two 8-Fr catheters were placed into the femoral veins. Cardiac arrest was induced with 60-Hz current. After 5 mins of no support, chest compression was performed by a circumferential pneumatic bladder (vest-cardiopulmonary resuscitation). Blood was withdrawn from one catheter by a pump system that maximized flow by servo-control of inlet pressure, was cooled, and was returned through the other catheter. Four dogs were instrumented similarly, and cooling was performed during normal circulation. In the pigs, baseline temperatures were (mean +/- SEM) 37 +/- 1 degree C. With blood cooling in the external chiller to 10 degrees C, cerebral and right atrial temperatures were reduced by 0.49 +/- 0.09 and 0.67 +/- 0.21 degrees C/min, respectively, for 10 mins. With blood cooling in the external chiller to 4 degrees C, cerebral and right atrial temperatures were reduced by 0.61 +/- 0.18 and 1.56 +/- 0.33 degrees C/min, respectively. Cerebral cooling lagged behind right atrial cooling. There was a strong correlation between coronary perfusion pressure (aortic to right atrial mean decompression-phase pressure) and cerebral cooling rate (r = .79; p < .022). Rates of cooling during normal circulation in dogs were similar. Rapid induction of mild hypothermia is feasible with a system that uses venous access, standard access techniques, and external chest compression. Induction of mild hypothermia during cardiac arrest in the field appears feasible and may allow the benefit of very early induction of hypothermia to be determined in patients.