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Biomedical subjects

Lars Wik

Publications and source records attributed to Lars Wik.

At least 19 recordsLinked to original sources
PubMed2006

Quality of out-of-hospital cardiopulmonary resuscitation with real time automated feedback: a prospective interventional study.

AIMS: To compare quality of CPR during out-of-hospital cardiac arrest with and without automated feedback. MATERIALS AND METHODS: Consecutive adult, out-of-hospital cardiac arrests of all causes were studied. One hundred and seventy-six episodes (March 2002-October 2003) without feedback were compared to 108 episodes (October 2003-September 2004) where automatic feedback on CPR was given. Automated verbal and visual feedback was based on measured quality with a prototype defibrillator. Quality of CPR was the main outcome measure and survival was reported as specified in the protocol. RESULTS: Average compression depth increased from (mean +/- S.D.) 34 +/- 9 to 38 +/- 6 mm (mean difference (95% CI) 4 (2, 6), P < 0.001), and median percentage of compressions with adequate depth (38-51 mm) increased from 24% to 53% (P < 0.001, Mann-Whitney U-test) with feedback. Mean compression rate decreased from 121 +/- 18 to 109 +/- 12 min(-1) (difference -12 (-16, -9), P = 0.001). There were no changes in the mean number of ventilations per minute; 11 +/- 5 min(-1) versus 11 +/- 4 min(-1) (difference 0 (-1, 1), P = 0.8) or the fraction of time without chest compressions; 0.48 +/- 0.18 versus 0.45 +/- 0.17 (difference -0.03 (-0.08, 0.01), P = 0.08). With intention to treat analysis 7/241 control patients were discharged alive (2.9%) versus 5/117 with feedback (4.3%) (OR 1.5 (95% CI; 0.8, 3), P = 0.2). In a logistic regression analysis of all cases, witnessed arrest (OR 4.2 (95% CI; 1.6, 11), P = 0.004) and average compression depth (per mm increase) (OR 1.05 (95% CI; 1.01, 1.09), P = 0.02) were associated with rate of hospital admission. CONCLUSIONS: Automatic feedback improved CPR quality in this prospective non-randomised study of out-of-hospital cardiac arrest. Increased compression depth was associated with increased short-term survival. TRIAL REGISTRATION: ClinicalTrials.gov (NCT00138996), http://www.clinicaltrials.gov/.

Aged↗
PubMed2006

Quality of lay person CPR performance with compression: ventilation ratios 15:2, 30:2 or continuous chest compressions without ventilations on manikins.

The new CPR guidelines emphasise chest compression depth and have increased the compression:ventilation ratio to cause less time intervals without chest compressions. How this change may influence the quality of chest compressions is not documented. Sixty-eight volunteers among travellers at Oslo international airport and a senior citizen centre performed 5 min of CPR on a manikin with compression:ventilation ratios 15:2, 30:2 or continuous chest compressions. Median age was 37.5 years (range 15-87), 59% were men, and 71% reported CPR training median 8 years (3-15) previously. Three of 22, 4 of 23 and 3 of 23 subjects in the 15:2, 30:2 and continuous compressions groups respectively stopped before 5 min had passed. Mean compression depth was 41 +/- 11, 45 +/- 8 and 30 +/- 8 mm, respectively. Depth was reduced as a function of time in the continuous compression group. Number of compressions per minute was 40 +/- 9, 43 +/- 14 and 73 +/- 24 and percent no flow time 49 +/- 13%, 38 +/- 20% and 1 +/- 2%, respectively. In conclusion, continuous chest compressions without ventilations gave significantly more chest compressions per minute, but with decreased compression quality. No flow time for 30:2 was significantly less than for 15:2.

Adolescent↗
PubMed2006

Haemodynamic effects of adrenaline (epinephrine) depend on chest compression quality during cardiopulmonary resuscitation in pigs.

BACKGROUND: Adrenaline (epinephrine) is used during cardiopulmonary resuscitation (CPR) based on animal experiments without supportive clinical data. Clinically CPR was reported recently to have much poorer quality than expected from international guidelines and what is generally done in laboratory experiments. We have studied the haemodynamic effects of adrenaline during CPR with good laboratory quality and with quality simulating clinical findings and the feasibility of monitoring these effects through VF waveform analysis. METHODS AND RESULTS: After 4 min of cardiac arrest, followed by 4 min of basic life support, 14 pigs were randomised to ClinicalCPR (intermittent manual chest compressions, compression-to-ventilation ratio 15:2, compression depth 30-38 mm) or LabCPR (continuous mechanical chest compressions, 12 ventilations/min, compression depth 45 mm). Adrenaline 0.02 mg/kg was administered 30 s thereafter. Plasma adrenaline concentration peaked earlier with LabCPR than with ClinicalCPR, median (range), 90 (30, 150) versus 150 (90, 270) s (p = 0.007), respectively. Coronary perfusion pressure (CPP) and cortical cerebral blood flow (CCBF) increased and femoral blood flow (FBF) decreased after adrenaline during LabCPR (mean differences (95% CI) CPP 17 (6, 29) mmHg (p = 0.01), FBF -5.0 (-8.8, -1.2) ml min(-1) (p = 0.02) and median difference CCBF 12% of baseline (p = 0.04)). There were no significant effects during ClinicalCPR (mean differences (95% CI) CPP 4.7 (-3.2, 13) mmHg (p = 0.2), FBF -0.2 (-4.6, 4.2) ml min(-1)(p = 0.9) and CCBF 3.6 (-1.8, 9.0)% of baseline (p = 0.15)). Slope VF waveform analysis reflected changes in CPP. CONCLUSION: Adrenaline improved haemodynamics during laboratory quality CPR in pigs, but not with quality simulating clinically reported CPR performance.

Animals↗
PubMed2006

Effects of compression depth and pre-shock pauses predict defibrillation failure during cardiac arrest.

BACKGROUND: Cardiopulmonary resuscitation (CPR) and electrical defibrillation are the primary treatment options for ventricular fibrillation (VF). While recent studies have shown that providing CPR prior to defibrillation may improve outcomes, the effects of CPR quality remain unclear. Specifically, the clinical effects of compression depth and pauses in chest compression prior to defibrillation (pre-shock pauses) are unknown. METHODS: A prospective, multi-center, observational study of adult in-hospital and out-of-hospital cardiac resuscitations was conducted between March 2002 and December 2005. An investigational monitor/defibrillator equipped to measure compression characteristics during CPR was used. RESULTS: Data were analyzed from 60 consecutive resuscitations in which a first shock was administered for VF. The primary outcome was first shock success defined as removal of VF for at least 5s following defibrillation. A logistic regression analysis demonstrated that successful defibrillation was associated with shorter pre-shock pauses (adjusted odds ratio 1.86 for every 5s decrease; 95% confidence interval 1.10-3.15) and higher mean compression depth during the 30s of CPR preceding the pre-shock pause (adjusted odds ratio 1.99 for every 5mm increase; 95% confidence interval 1.08-3.66). CONCLUSIONS: The quality of CPR prior to defibrillation directly affects clinical outcomes. Specifically, longer pre-shock pauses and shallow chest compressions are associated with defibrillation failure. Strategies to correct these deficiencies should be developed and consideration should be made to replacing current-generation automated external defibrillators that require long pre-shock pauses for rhythm analysis.

Aged↗
PubMed2006

Airway management by paramedics using endotracheal intubation with a laryngoscope versus the oesophageal tracheal Combitube and EasyTube on manikins: a randomised experimental trial.

INTRODUCTION: The EasyTube, which is constructed in a similar way to the Combitube, is a recently introduced alternative to tracheal intubation for airway management in emergency medicine. OBJECTIVE: To determine if there is a difference in rate of, and time to, successful airway placement and ventilation using tracheal intubation, Combitube and EasyTube. METHODS: Twenty-six paramedics, trained in tracheal intubation received additional training in the use of the Combitube and the EasyTube. Each participant performed all three methods twice in random order on a manikin. Time to successful ventilation (presented as mean and standard deviation) and success rate were recorded. RESULTS: Mean time to successful ventilation was significantly longer for tracheal intubation (45.2 s (S.D.=15.8)) than for the Combitube (36.0 s (S.D. = 8.6)) p = 0.002 and the EasyTube (38.0 s (S.D.=15.3)) p = 0.023 with no difference between the latter (p = 1.000). Success rate for the Combitube and EasyTube combined (103/104) was significantly higher than for tracheal intubation (45/52) with odds ratio 16.0 (95% CI: 1.9-134); p = 0.002. CONCLUSION: For paramedics tested on manikins placement success rate was higher with less time required for the Combitube and Easytube than for tracheal intubation with no differences between the Combitube and EasyTube.

Adult↗
PubMed2005

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

STUDY HYPOTHESIS: Tracheal intubation should improve the quality of cardiopulmonary resuscitation (CPR) by enabling adequate ventilation without pauses in external chest compressions. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Advanced Cardiac Life Support↗
PubMed2005

Cardiac arrest and resuscitation with an automatic mechanical chest compression device (LUCAS) due to anaphylaxis of a woman receiving caesarean section because of pre-eclampsia.

We report a case of anaphylaxis with pulseless electrical activity (PEA)(verified by ECG and a radial intra-arterial line) in a 30-year-old woman who received 3G Promiten (dextran-1) and a prophylactic intra-venous infusion of Macrodex (dextran) for postoperative thromboembolism during caesarean section for pre-eclampsia in the 24th week of gestation. Manual chest compressions, followed by mechanical chest compressions (LUCAS, Jolife, Lund, Sweden), were performed for 50min before restoration of spontaneous circulation (ROSC). She awoke the next day with no sequelae. She had some suction cup marks on the sternum but otherwise no complications of the chest compressions. At follow up by phone 1 month later, she and her baby were doing well.

Adult↗
PubMed2005

Quality of cardiopulmonary resuscitation during out-of-hospital cardiac arrest.

CONTEXT: Cardiopulmonary resuscitation (CPR) guidelines recommend target values for compressions, ventilations, and CPR-free intervals allowed for rhythm analysis and defibrillation. There is little information on adherence to these guidelines during advanced cardiac life support in the field. OBJECTIVE: To measure the quality of out-of-hospital CPR performed by ambulance personnel, as measured by adherence to CPR guidelines. DESIGN AND SETTING: Case series of 176 adult patients with out-of-hospital cardiac arrest treated by paramedics and nurse anesthetists in Stockholm, Sweden, London, England, and Akershus, Norway, between March 2002 and October 2003. The defibrillators recorded chest compressions via a sternal pad fitted with an accelerometer and ventilations by changes in thoracic impedance between the defibrillator pads, in addition to standard event and electrocardiographic recordings. MAIN OUTCOME MEASURE: Adherence to international guidelines for CPR. RESULTS: Chest compressions were not given 48% (95% CI, 45%-51%) of the time without spontaneous circulation; this percentage was 38% (95% CI, 36%-41%) when subtracting the time necessary for electrocardiographic analysis and defibrillation. Combining these data with a mean compression rate of 121/min (95% CI, 118-124/min) when compressions were given resulted in a mean compression rate of 64/min (95% CI, 61-67/min). Mean compression depth was 34 mm (95% CI, 33-35 mm), 28% (95% CI, 24%-32%) of the compressions had a depth of 38 mm to 51 mm (guidelines recommendation), and the compression part of the duty cycle was 42% (95% CI, 41%-42%). A mean of 11 (95% CI, 11-12) ventilations were given per minute. Sixty-one patients (35%) had return of spontaneous circulation, and 5 of 6 patients discharged alive from the hospital had normal neurological outcomes. CONCLUSIONS: In this study of CPR during out-of-hospital cardiac arrest, chest compressions were not delivered half of the time, and most compressions were too shallow. Electrocardiographic analysis and defibrillation accounted for only small parts of intervals without chest compressions.

Aged↗
PubMed2005

Twelve-month retention of CPR skills with automatic correcting verbal feedback.

AIM: To evaluate the retention of CPR skills 12 months after initial training, using a manikin equipped with a computer-based voice advisory feedback system. METHODS: Thirty-five volunteers had individual 20 min training sessions without an instructor on a manikin with computer-based voice advisory feedback. The feedback depended on the performance as measured by the manikin computer system versus set limits for ventilation and compression variables. Twelve of the volunteers received additional ten 3-min self-training sessions during the following month making a total of 50 min training. All ventilation and compression variables when the volunteers were tested before, immediately after and 6 months after training have previously been reported. The volunteers were now tested 12 months after the initial training session with activated feedback. RESULTS: There were virtually no changes in CPR skills when tested with active feedback 12 months after initial training versus immediately or 6 months post-training. The only exception was a slightly lower number of compressions per minute at 12 months versus immediate post-training in the subgroup with 20 min of initial training, 47+/-4 versus 52+/-4, p = 0.008. There were no differences between the 20 and 50 min training subgroups at 12 months. CONCLUSIONS: Computer-based voice advisory feedback can improve the performance of basic life support skills on a manikin with no deterioration in feedback supported performance after 12 months.

Cardiopulmonary Resuscitation↗
PubMed2005

Use of an automatic mechanical chest compression device (LUCAS) as a bridge to establishing cardiopulmonary bypass for a patient with hypothermic cardiac arrest.

We report the case of a victim of deep accidental hypothermia who was extracted from the ice and received 1.5 h of mechanical chest compression. This was followed with rapid rewarming on cardiopulmonary bypass and resulted in good physical and mental recovery. This management option should be considered for similar victims.

Cardiopulmonary Bypass↗
PubMed2005

Independent evaluation of a defibrillation outcome predictor for out-of-hospital cardiac arrested patients.

We evaluated the ability of a previously derived outcome predictor to discriminate between ECG segments corresponding to return of spontaneous circulation (ROSC) or not in validation data from 136 patients with cardiac arrest. The new data used for validation were totally independent from the predictor derivation data used in the original study. Features corresponding to those used in the development of the original outcome predictor, centroid frequency, peak power frequency, spectral flatness and energy, were computed following which a second decorrelated feature set was generated. The outcome predictor was applied to the new data with good correspondence in performance (testing) to what was expected (training) with receiver operator characteristics (ROC) areas of 0.80 and 0.79, respectively. Outcome predictor performance was reproducible. As in the present study, future testing should be performed on totally independent data not included in the design of the outcome predictor to get a reliable impression of expected performance.

Cardiopulmonary Resuscitation↗
PubMed2004

Effects of cardiopulmonary resuscitation on predictors of ventricular fibrillation defibrillation success during out-of-hospital cardiac arrest.

BACKGROUND: Early defibrillation is considered the most important factor for restoring spontaneous circulation in cardiac arrest patients with ventricular fibrillation. Recent studies have shown that, after prolonged ventricular fibrillation, the rates of return of spontaneous circulation (ROSC) and survival are improved if defibrillation is delayed so that CPR can be given first. To examine whether CPR improves myocardial readiness for defibrillation, we analyzed whether CPR causes changes in predictors of defibrillation success calculated from the ventricular fibrillation waveform. METHODS AND RESULTS: ECG recordings were retrieved for 105 patients from an original study of 200 patients receiving CPR or defibrillation first. Altogether, 267 CPR sequences from 77 patients were identified on which the effect of CPR could be evaluated. Five predictors of ROSC (spectral flatness measure, energy, centroid frequency, amplitude spectrum relationship, and estimated probability of ROSC) were determined from a spectral analysis of the ventricular fibrillation waveform immediately before and immediately after each of the 267 sequences. CPR increased spectral flatness measure, centroid frequency, and amplitude spectrum relationship (P<0.05, P<0.001, P<0.01). In an analysis of the effect of the duration of CPR, the probability of ROSC and amplitude spectrum relationship showed a positive change for CPR sequences lasting >3 minutes (P<0.001, P<0.05). CONCLUSIONS: During resuscitation from ventricular fibrillation, changes in the predictors calculated from the ventricular fibrillation waveform indicated a positive effect of CPR on the myocardium.

Cardiopulmonary Resuscitation↗
PubMed2004

Rapid extrication from a car wreck.

Extrication of entrapped patients from car accidents takes time. To save time a new technique based on reversing the forces of the original crash by anchoring the rear of the vehicle and pulling the steering wheel and the front window pillars forward with chains is developed. In an experimental randomised trial of extrication of volunteers from car wrecks after frontal/oblique impacts we wanted to evaluate the time spent with a new extrication technique (n=6) compared to standard (n=6). Main outcome measures were time to patient free and to patient on a stretcher. It took significantly longer (s) with the standard than the new technique to start extrication [(60 (45, 70) versus 30 (30, 40), confidence interval (CI) 5-40, P=0.009], to patient free in the front seat [514+/-102 versus 238+/-72, CI 163-389, P=0.001], backboard in place [543+/-102 versus 295+/-76, CI 132-363, P=0.001], and patient on the stretcher ready for transport to the hospital [617+/-112 versus 387+/-65, CI 112-347, P=0.001]. Avoiding uncontrolled movements in the wreck was not more difficult with the new than the standard technique.

Accidents, Traffic↗
PubMed2003

Delaying defibrillation to give basic cardiopulmonary resuscitation to patients with out-of-hospital ventricular fibrillation: a randomized trial.

CONTEXT: Defibrillation as soon as possible is standard treatment for patients with ventricular fibrillation. A nonrandomized study indicates that after a few minutes of ventricular fibrillation, delaying defibrillation to give cardiopulmonary resuscitation (CPR) first might improve the outcome. OBJECTIVE: To determine the effects of CPR before defibrillation on outcome in patients with ventricular fibrillation and with response times either up to or longer than 5 minutes. DESIGN, SETTING, AND PATIENTS: Randomized trial of 200 patients with out-of-hospital ventricular fibrillation in Oslo, Norway, between June 1998 and May 2001. Patients received either standard care with immediate defibrillation (n = 96) or CPR first with 3 minutes of basic CPR by ambulance personnel prior to defibrillation (n = 104). If initial defibrillation was unsuccessful, the standard group received 1 minute of CPR before additional defibrillation attempts compared with 3 minutes in the CPR first group. MAIN OUTCOME MEASURE: Primary end point was survival to hospital discharge. Secondary end points were hospital admission with return of spontaneous circulation (ROSC), 1-year survival, and neurological outcome. A prespecified analysis examined subgroups with response times either up to or longer than 5 minutes. RESULTS: In the standard group, 14 (15%) of 96 patients survived to hospital discharge vs 23 (22%) of 104 in the CPR first group (P =.17). There were no differences in ROSC rates between the standard group (56% [58/104]) and the CPR first group (46% [44/96]; P =.16); or in 1-year survival (20% [21/104] and 15% [14/96], respectively; P =.30). In subgroup analysis for patients with ambulance response times of either up to 5 minutes or shorter, there were no differences in any outcome variables between the CPR first group (n = 40) and the standard group (n = 41). For patients with response intervals of longer than 5 minutes, more patients achieved ROSC in the CPR first group (58% [37/64]) compared with the standard group (38% [21/55]; odds ratio [OR], 2.22; 95% confidence interval [CI], 1.06-4.63; P =.04); survival to hospital discharge (22% [14/64] vs 4% [2/55]; OR, 7.42; 95% CI, 1.61-34.3; P =.006); and 1-year survival (20% [13/64] vs 4% [2/55]; OR, 6.76; 95% CI, 1.42-31.4; P =.01). Thirty-three (89%) of 37 patients who survived to hospital discharge had no or minor reductions in neurological status with no difference between the groups. CONCLUSIONS: Compared with standard care for ventricular fibrillation, CPR first prior to defibrillation offered no advantage in improving outcomes for this entire study population or for patients with ambulance response times shorter than 5 minutes. However, the patients with ventricular fibrillation and ambulance response intervals longer than 5 minutes had better outcomes with CPR first before defibrillation was attempted. These results require confirmation in additional randomized trials.

Adult↗
PubMed2003

Evaluation of a defibrillator-basic cardiopulmonary resuscitation programme for non medical personnel.

To improve the outcome for out-of-hospital patients with ventricular fibrillation/pulseless ventricular tachycardia (VF/VT), the use of automated external defibrillators (AEDs) by first responders including non-medical personnel with a duty to respond to an emergency is recommended. A special CPR-AED course has been developed. We wanted to test the results (quality and speed of operating an AED and CPR) after completion of such a course and retention after approximately 1-year. At the same time we wanted to see if personnel could use an AED after receiving written information without having attended the course. Study subjects were divided randomly into groups, and tested pre-course (n=54), post-course (n=50), and unannounced 10+/-3 months after the course (retention group, n=61). For statistical analysis two sample tests for binomial proportions and Wilcoxon-Mann-Whitney test was used as appropriate. Fifteen of the 27 pairs (56%) in the pre-course group with no previous exposure to an AED decided to use it. There was no difference between the groups in electrode pad positioning, and all stayed clear of the manikin during the process of AED charging and shock delivery. The post-course group had a higher rate of checking for responsiveness (vs. pre-course), not to check for a pulse (vs. both other groups), the shortest time interval from arrival on scene to start of CPR and shock delivery, and in parallel the shortest hands-off interval (without chest compressions and ventilations) before shock delivery. The quality of chest compressions was improved by the course but decreased to a similar standard as in the pre-course when tested 10+/-3 months later, except for correct depth which was similar to post course. Most ventilation attempts in all groups were scored as incorrect due to the high incidence of excessively rapid inflations. The retention group had a lower frequency of correct inflations than the pre-course group, and the post-course group the highest number of correct ventilations per minute. These findings suggest that use of an AED by untrained laypersons may be feasible and that complex and time-consuming training programmes may not be necessary. The present study also supports the need for annual training and recertification.

Cardiopulmonary Resuscitation↗