Decrease in the occurrence of ventricular fibrillation as the initially observed arrhythmia after out-of-hospital cardiac arrest during 11 years in Sweden

Aim: To describe the change in the occurrence of ventricular fibrillation as initially observed arrhythmia among patients suffering from out-of-hospital cardiac arrest in Sweden. Patients: All patients included in the Swedish cardiac arrest registry between 1991 until 2001. The registry covers 85% of the population in Sweden. Methods: All patients with bystander witnessed out-of-hospital cardiac arrest included in the Swedish Cardiac Arrest Registry between 1991 and 2001 from the same ambulance organisation each year were included in the survey. Results: Over 11 years, among patients in Sweden with a bystander witnessed out-of-hospital cardiac arrest in whom cardiopulmonary resuscitation (CPR) was attempted (n=9666), the occurrence of ventricular fibrillation as the initially obseved arrhythmia decreased from 45% in 1991 to 28% in 2001 (P<0.0001) if the arrest occurred at home, and from 57% to 41% if the arrest occurred outside home (P<0.0001). This was found despite the fact that the proportion who received bystander CPR increased from 29% in 1991 to 39% in 2001 if the arrest occurred at home (P<0.0001) and from 54% to 60% if the arrest occurred outside home (NS). There was a significant increase in age among patients with out-of-hospital cardiac arrest at home, no change in the estimated interval between collapse and call but an increase in the interval between call and arrival of the ambulance among patients with out-of-hospital cardiac arrest outside home. Conclusion: During 11 years in Sweden, there was a marked decrease in the proportion of patients found in ventricular fibrillation among patients with a bystander witnessed cardiac arrest regardless whether the arrest occurred at home or outside home. A modest increase in age and interval between call for, and arrival of, the ambulance was associated with these findings.     

Can successful treatment of cardiac arrest be a performance indicator for hospitals?

BACKGROUND: Although resuscitation from cardiac arrest prevents more deaths from acute myocardial infarction (MI) than any other treatment, results have not been audited widely nor performance standards proposed. METHODS: The Myocardial Infarction National Audit Project (MINAP) uses electronic transmission of a 53-item dataset to a central cardiac audit database (CCAD). From October 2000 to August 2002, transmission by 218 hospitals of data from 55,906 cases of MI with 4934 attempted resuscitations from a first arrest, allowed for examination of factors determining survival, and for possible future measurement of success in resuscitation as a performance indicator. We investigated two possible indicators: (i) numbers of survivors from arrest in ventricular fibrillation or pulseless ventricular tachycardia (VF/VT) per 1000 cases of MI; and (ii) observed/expected (O/E) ratios for survival taking all VF/VT arrests rather than MI as the denominator, and adjusting for differing age structures and admission delays among individual hospitals. FINDINGS: Of the 4934 reported patients suffering a first arrest, 1778 (36%) survived to be discharged from hospital. The presenting rhythm was VF/VT in 2321 (47%) patients of whom 1461 (63%) survived. Survival for all 218 hospitals together had the relatively small 95% confidence limits of 26 (25-27) survivors from VF/VT per 1000 MI. However, the small numbers from individual hospitals made it impossible in most cases, whichever of the two indicators was used, to separate quality of performance and completeness of reporting from the factor of chance. INTERPRETATION: Audit of success in resuscitation is essential if performance in the treatment of MI is to be assessed. However, the relatively small numbers of arrests occurring in individual hospitals means that if year on year improvements are to be documented, audit must be carried out among groups of hospitals or on a national scale.     

Ambulance crew assessment of trauma severity and alerting practice for trauma patients brought to a general hospital

Introduction: Ambulance crews may alert hospitals for patients who are severely unwell. This allows the hospital time to prepare space and equipment, and to assemble an appropriate clinical team to receive and manage the patient immediately on arrival. Over and under alerting by ambulance crews is to be avoided to avoid complacency on one hand, and inadequate reception of severely injured patients on the other. There are currently no formal guidelines for the ambulance service to alert hospitals in appropriate cases. Aims: To describe the current alerting practice for trauma patients by ambulance crews to a large urban hospital. Methods: Details of each trauma alert for the hospital for the year 2000 were identified. The Injury Severity Score (ISS) was determined for all trauma patients who were eligible for inclusion into the Trauma Audit Research Network (TARN) for the same year. The two populations were compared. Results: There were 145 trauma patients for whom an alert was made during the year 2000, and there were 504 patients eligible for inclusion into TARN. Ten percent (49) of the TARN patients had an ISS>15. Twenty-five percent (35/135) of the trauma patients with alerts had been entered into TARN. Seventy-five percent (100/135) of the trauma patients with alerts did not meet the criteria for inclusion into TARN. Forty-three percent (15/35) of the trauma patients with alerts who appeared in TARN had an ISS>15 (11% of all trauma alerts). Thirty-four TARN-eligible patients with an ISS>15 were not the subject of a hospital alert. Conclusions: The majority of patients with major trauma (ISS>15) were not the subject of a hospital alert by the ambulance service. Seventy-five percent of the patients who were the subject of an alert were not eligible for inclusion into TARN, implying that they did not have serious injury. Pre-hospital trauma severity assessment needs developing with appropriate ambulance protocols, to ensure appropriate alert calls.     

Massive chloroquine intoxication: importance of early treatment and pre-hospital treatment

Chloroquine intoxication, despite therapeutic improvements, remains a potentially serious condition. We report a case of a 25-year-old patient, having ingested 10 g of chloroquine, a dose commonly considered to be lethal. Thanks to appropriate early medical treatment, this patient’s outcome was favourable. To our knowledge, the literature contains no other report of survival of a patient after such an intake. This report emphasises the need to use a pre-designed medical care protocol to implement appropriate therapy as rapidly as possible.     

The effect of mild therapeutic hypothermia on renal function after cardiopulmonary resuscitation in men

Background: Mild therapeutic hypothermia (MTH) improves neurological outcome in patients after cardiac arrest. From animal and human studies it appears that hypothermia impairs renal function. The aim of this study was to examine the effects of MTH on renal function in humans. Methods: Patients were participants recruited in one of the centres of the hypothermia after cardiac arrest-multicenter trial. We measured serum creatinine and creatinine clearance (C_Cr) within 24 h of MTH, at 4 hourly intervals. Patients were followed for acute renal failure and need for renal supportive therapy for 28 days. Results: We included 60 patients (32 hypothermic, 28 normothermic). Median serum creatinine on admission was [{119 μmol/l (IQR 108–133)} {1.35 mg/dl (IQR 1.22–1.50)}] in hypothermic and [{114 μmol/l (IQR 99–131)} {1.29 mg/dl (IQR 1.12–1.48)}] in normothermic patients, and decreased to [{69 μmol/l (IQR 62–84)} {0.78 mg/dl (IQR 0.70–0.95)}] in the hypothermic group and to [{88 μmol/l (IQR 71–123)} {1.00 mg/dl (IQR 0.80–1.39)}] in the normothermic group within 24 h. C_Cr was decreased on admission. Within 24 h C_Cr improved to normal values in normothermic patients [1.53 ml/s (IQR 1.15–2.35) {92 ml/min (IQR 69–141)}] and remained low in hypothermic patients [0.88 ml/s (IQR 0.63–1.38) {53 ml/min (IQR 38–83)}] (P=0.0006). No difference was found between the groups in the development of acute renal failure or the need for renal supportive therapy. Conclusion: Twenty four hours of MTH was associated with a delayed improvement in renal function. This was not reflected in the serum creatinine values, which were low in the hypothermic group. This transient impaired renal function appeared to be completely reversible within 4 weeks.     

Recovery from near death following cerebral anoxia: A case report demonstrating superiority of median somatosensory evoked potentials over EEG in predicting a favorable outcome after cardiopulmonary resuscitation

An electroencephalogram disclosing electrocerebral silence (ECS) after cardiopulmonary resuscitation (CPR) is usually considered an unfavorable prognostic indicator associated with brain death or persistent vegetative state. I report a case of a comatose patient following cardiac arrest, whose initial electroencphalography (EEG) was isoelectric taken 5 h after onset. Median somatosensory evoked potentials (SSEP) obtained immediately after the initial EEG were normal. He then underwent gradual recovery of neurologic function with incremental improvement on serial EEG study, and eventually achieved full neurological recovery. SSEP proved to be a more reliable predictor of a neurological outcome that was ultimately favorable.     

Cardiopulmonary resuscitation (CPR) using periodic acceleration (pGz) in an older porcine model of ventricular fibrillation

Cardiopulmonary resuscitation (CPR) can be achieved by repetitive motion of the body headwards to footwards in the spinal axis, at 2 Hz and ±0.6 G in a juvenile pig model of ventricular fibrillation. Return of spontaneous circulation and normal neurological outcome occurred after a total of 22 min of ventricular fibrillation that included a 3-min noninterventional period [Resuscitation 56 (2003) 215; Resuscitation 51 (2001) 55]. Since older pigs have stiffer rib cages than juvenile pigs and their hemodynamic response to various stimuli might differ, this study was carried out to determine whether this method of CPR, termed pGz-CPR, was just as effective in older pigs. pGz-CPR was also compared to chest compression CPR using an automated mechanical device (CONV-CPR). Ventricular fibrillation was instituted in older pigs weighing 23–34 kg and a 3-min noninterventional period was observed, followed by 15 min pGz-CPR in eight pigs or 15 min CONV-CPR in eight pigs. Return of spontaneous circulation (ROSC) occurred after defibrillation in all eight pigs with pGz-CPR and in six of eight pigs with CONV-CPR. Two of eight pigs with CONV-CPR and none of the eight pigs with pGz-CPR had rib fractures. Hemodynamic instability 15 min after ROSC occurred in all animals with CONV-CPR whereas only three of eight pigs with pGz-CPR demonstrated hemodynamic instability (P<0.05). We conclude that pGz-CPR in older pigs produces similar ROSC reported by other investigators in pigs without the risk of rib fractures. Further, pGz-CPR is associated with a lower incidence of periods of hemodynamic instability following ROSC than CONV-CPR.     

Effects of intraaortic balloon augmentation in a porcine model of endotoxemic shock

Objective: Patients with septic shock commonly have myocardial dysfunction associated with lactic acid production and troponin I release. The purpose of this study was to evaluate the effects on intraaortic balloon pump (IABP) support on myocardial dysfunction. Design: Prospective, randomized controlled study. Setting: Animal research laboratory. Methods: Ten pigs had arterial, pulmonary arterial, and coronary catheters inserted. After receiving endotoxin infusion over 30 min, half the animals received IABP support. Results: Coronary sinus lactic acid levels (P<0.05 for both 90 min versus baseline and 60 min versus baseline) and arterial lactic acid levels (P<0.05 for both 90 min versus baseline and 60 min versus baseline) increased with time but did not differ between IABP and sham groups. While overall there was no difference with time in myocardial lactic acid consumption or production (calculated as arterial lactic acid level minus coronary sinus lactic acid level), the IABP group showed net myocardial lactic acid consumption at 90 min, while the sham group showed myocardial lactic acid production. Three of five animals in each group showed troponin I release. The levels were similar and did not differ between groups. Conclusion: IABP had no benefits in this porcine model of endotoxemic shock.     

Oxygen delivery and return of spontaneous circulation with ventilation:compression ratio 2:30 versus chest compressions only CPR in pigs

The need for rescue breathing during the initial management of sudden cardiac arrest is currently being debated and reevaluated. The present study was designed to compare cerebral oxygen delivery during basic life support (BLS) by chest compressions only with chest compressions plus ventilation in pigs with an obstructed airway mimicked by a valve hindering passive inhalation. Resuscitability was then studied during the subsequent advanced life support (ALS) period. After 3 min of untreated ventricular fibrillation (VF) BLS was started. The animals were randomised into two groups. One group received chest compressions only. The other group received ventilations and chest compressions with a ratio of 2:30. A gas mixture of 17% oxygen and 4% carbon dioxide was used for ventilation during BLS. After 10 min of BLS, ALS was provided. All six pigs ventilated during BLS attained a return of spontaneous circulation (ROSC) within the first 2 min of advanced cardiopulmonary resuscitation (CPR) compared with only one of six compressions-only pigs. While all except one compressions-only animal achieved ROSC before the experiment was terminated, the median time to ROSC was shorter in the ventilated group. With a ventilation:compression ratio of 2:30 the arterial oxygen content stayed at 2/3 of normal, but with compressions-only, the arterial blood was virtually desaturated with no arterio-venous oxygen difference within 1.5–2 min. Haemodynamic data did not differ between the groups. In this model of very ideal BLS, ventilation improved arterial oxygenation and the median time to ROSC was shorter. We believe that in cardiac arrest with an obstructed airway, pulmonary ventilation should still be strongly recommended.     

A randomized trial of suprasternal palpation to determine endotracheal tube position in neonates

Objective: To compare suprasternal palpation, a previously described bedside technique, with standard chest radiography for correct positioning of the endotracheal tube (ETT) in newborn infants. Study design: A randomized single-blinded study in an academic medical center. Preterm and term newborn infants requiring intubation were eligible, provided that they had not had their initial chest roentgenogram (CXR). Infants were randomized to ETT palpation and non-adjustment (Controls), or to ETT palpation and adjustment (Treatment), following digital palpation of the ETT tip in the suprasternal notch. ETT position was considered correct when only the tip of the ETT was palpable in the suprasternal notch. ETT position by CXR was blindly assessed by an experienced pediatric radiologist. Results: Fifty-five infants were enrolled in the delivery room or neonatal intensive care unit. Correct tube placements improved from 48% pre-study to 85 and 93% in the Control and Treatment arms, respectively. The majority of incorrect estimations were that the ETT position using palpation was judged to be too low when it was, in fact, in correct position, as noted in 11 infants. ETT palpation had a 70% concordance with the position determined by CXR. No difficulties or complications were associated with the use of suprasternal palpation. Conclusions: Suprasternal palpation is a simple, safe, teachable, method of confirming ETT position in neonates when CXR is unavailable, and may especially helpful during neonatal resuscitation prior to surfactant administration.     

Hepatic portal venous gas associated with poor outcome in out-of-hospital cardiac arrest patients

Objectives: To determine the incidence of sonographic hepatic portal venous gas (HPVG) and to clarify the relationship between the presence of HPVG and clinical outcomes in patients with out-of-hospital cardiac arrest (OHCA). Methods: From April 2002 to January 2003, patients with non-traumatic OHCA were prospectively enrolled in a tertiary medical centre in Taipei, Taiwan. Emergency abdominal sonography during resuscitation was performed to detect the presence of HPVG within the first 10 min on arrival of the emergency department (ED). Results: HPVG was detected in 16 (36%) of the 44 patients enrolled in this study. The patients with HPVG were older (P=0.039), their cardiac arrest was witnessed less frequently (P=0.01), they received more prolonged resuscitation (P=0.008), and needed more accumulated doses of adrenaline (epinephrine) (P=0.002). These patients had a considerably lower incidence of return of spontaneous circulation (ROSC) (P<0.001), less survival to hospital admission (P<0.001), less 24 h survival (P<0.001) and less survival to discharge (P=0.036). In a multiple regression analysis, HPVG was noted as an independent factor negatively associated with ROSC. Conclusion: HPVG is not uncommon in patients receiving resuscitation for OHCA and is associated with poor outcome in these patients.     

Near-infrared laser photothermal therapy of cancer by using gold nanoparticles: Computer simulations and experiment

We describe applications of silica(core)/gold(shell) nanoparticles to photothermal therapy of spontaneous tumor of cats and dogs. The laser irradiation parameters was optimized by preliminary experiments with laboratory rats. The temperature distribution in tissue and solution samples was measured with a thermal imaging system. It is shown that the temperature in the volume region of nanoparticles localization can substantially exceed the surface temperature recorded by the thermal imaging system. We demonstrate effective optical destruction of cancer cells by local injection of plasmon-resonant gold nanoshells followed by continuous wave (CW) semiconductor laser irradiation at wavelength 808 nm.