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Biomedical subjects

L Wik

Publications and source records attributed to L Wik.

At least 19 recordsLinked to original sources
PubMed2004

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.

Animals↗
PubMed2004

Arterial blood gases with 700 ml tidal volumes during out-of-hospital CPR.

The optimal tidal and minute ventilation during cardiopulmonary resuscitation (CPR) is not known. In the present study seven adult, non-traumatic, out-of-hospital cardiac arrest patients were intubated and mechanically ventilated at 12 min(-1) with 100% oxygen and a tidal volume of 700 ml (10 +/- 2 ml kg(-1)). Arterial blood gas samples were analysed after 6-8 min of unsuccessful resuscitation and mechanical ventilation. Mean PaCO2 was 5.2 +/- 1.3 kPa and mean PaO2 30.7 +/- 17.2 kPa. The patient with the highest (14 ml kg(-1)) and lowest (8 ml kg(-1)) tidal volumes per kg had the lowest and highest PaCO2 values of 2.6 and 6.8 kPa, respectively. Linear regression analysis confirmed a significant correlation between arterial pCO2 and tidal volume in ml/kg, r2 = 0.87. We conclude that aiming for an estimated ventilation of 10 ml kg(-1) tidal volume at frequency of 12 min(-1) might be expected to achieve normocapnia during ALS.

Aged↗
PubMed2003

Dispatcher-assisted cardiopulmonary resuscitation. An evaluation of efficacy amongst elderly.

Bystander cardiopulmonary resuscitation (CPR) increases survival rates. The largest group of cardiac arrest patients are men over the age of 60 in the home, and the most probable potential CPR provider is an older woman who is not likely to have received CPR training. One method to increase the percentage of bystander-initiated CPR in this setting is for CPR instruction to be provided by nurse dispatchers via telephone. Two male and 18 female volunteers with a median age of 78 years and no previous CPR experience performed 9 min of telephone assisted CPR on a manikin. They were randomised to receive telephone instructions in chest compressions alone or standard CPR including mouth-to-mouth ventilation. Variables were registered by a recording manikin, visual observations, and video and audiotape recordings. The median period from dispatcher contact until continuous CPR was significantly longer for standard instructions than for compression only, 4.9 versus 3.4 min, and fewer chest compressions were provided during the 9 min test period, median 124 versus 334 compressions. In both groups the overall CPR performance was of very poor quality, and unlikely to have affected outcome in a real situation. Other telephone assisted CPR scripts should be tested in this potential bystander group.

Aged↗
PubMed2003

Quality of CPR with three different ventilation:compression ratios.

Current adult basic cardiopulmonary resuscitation (CPR) guidelines recommend a 2:15 ventilation:compression ratio, while the optimal ratio is unknown. This study was designed to compare arterial and mixed venous blood gas changes and cerebral circulation and oxygen delivery with ventilation:compression ratios of 2:15, 2:50 and 5:50 in a model of basic CPR. Ventricular fibrillation (VF) was induced in 12 anaesthetised pigs, and satisfactory recordings were obtained from 9 of them. A non-intervention interval of 3 min was followed by CPR with pauses in compressions for ventilation with 17% oxygen and 4% carbon dioxide in a randomised, cross-over design with each method being used for 5 min. Pulmonary gas exchange was clearly superior with a ventilation:compression ratio of 2:15. While the arterial oxygen saturation stayed above 80% throughout CPR for 2:15, it dropped below 40% during part of the ventilation:compression cycle for both the other two ratios. On the other hand, the ratio 2:50 produced 30% more chest compressions per minute than either of the two other methods. This resulted in a mean carotid flow that was significantly higher with the ratio of 2:50 than with 5:50 while 2:15 was not significantly different from either. The mean cerebrocortical microcirculation was approximately 37% of pre-VF levels during compression cycles alone with no significant differences between the methods. The oxygen delivery to the brain was higher for the ratio of 2:15 than for either 5:50 or 2:50. In parallel the central venous oxygenation, which gives some indication of tissue oxygenation, was higher for the ratio of 2:15 than for both 5:50 and 2:50. As the compressions were done with a mechanical device with only 2-3 s pauses per ventilation, the data cannot be extrapolated to laypersons who have great variations in quality of CPR. However, it might seem reasonable to suggest that basic CPR by professionals should continue with ratio of 2:15 at present if it can be shown that similar brief pauses for ventilation can be achieved in clinical practice.

Animals↗
PubMed2002

Effectiveness of ventilation-compression ratios 1:5 and 2:15 in simulated single rescuer paediatric resuscitation.

Current guidelines for paediatric basic life support (BLS) recommend a ventilation-compression ratio of 1:5 during child resuscitation compared with 2:15 for adults, based on the consensus that ventilation is more important in paediatric than in adult BLS. We hypothesized that the ratio 2:15 would provide the same minute ventilation as 1:5 during single-rescuer paediatric BLS due to the reduced time required to change between ventilations and compressions. Fourteen lay rescuers were trained with both ratios and thereafter performed single rescuer BLS for approximately 4 min with each of the two ratios in random order on a child-sized manikin with a built-in respiratory monitor. Quality of chest compressions was assessed by measurement of the rate, depth and position. There were no significant differences in tidal volumes or minute ventilation between the ratios. Nearly all chest compressions were within acceptable limits for depth and place with both methods, but the mean number of chest compressions per minute was 48+/-15% greater with ratio 2:15. In conclusion, there was no difference in ventilation, but nearly one and a half times as many compressions with a ratio of 2:15 than 1:5 for lay rescuers during single rescuer paediatric CPR. In order to simplify CPR training for laypersons, we recommend a 2:15 ratio for both single- and two-person, adult and paediatric layperson BLS.

Adult↗
PubMed2001

An automated voice advisory manikin system for training in basic life support without an instructor. A novel approach to CPR training.

Twenty-four paramedic students with previous basic life support training were randomised, performing cardiopulmonary resuscitation (CPR) on a manikin for 3 min without any feedback followed by 3 min of CPR with audio feedback from the manikin after a 2-min break, or vice versa. A computer recorded information on timing, ventilation flow rates and volumes and all movements of the sternum of the manikin. The software allowed acceptable limits to be set for all ventilation and compression/release variables giving appropriate on-line audio feedback according to these settings from among approximately 40 pre-recorded messages. Students who started without feedback significantly improved after feedback in terms of the median percentage of correct inflations (from 2 to 64%), with most inflations being rapid before feedback (94%), compressions of correct depth (from 32 to 92%), and the duration of compressions in the duty cycle (from 41 to 44%). There were no problems with the median compression rate, sternal release during decompressions, or the hand position, even before feedback. There were no significant differences in any variables with and without feedback for the students who started with feedback, or between the audio feedback periods of the two groups. It is concluded that this automated voice advisory manikin system, a novel approach to basic CPR training, caused an immediate improvement in the skills performance of paramedic students.

Allied Health Personnel↗
PubMed2000

Airway pressure with chest compressions versus Heimlich manoeuvre in recently dead adults with complete airway obstruction.

In a previous case report a standard chest compression successfully removed a foreign body from the airway after the Heimlich manoeuvre had failed. Based on this case, standard chest compressions and Heimlich manoeuvres were performed by emergency physicians on 12 unselected cadavers with a simulated complete airway obstruction in a randomised crossover design. The mean peak airway pressure was significantly lower with abdominal thrusts compared to chest compressions, 26.4+/-19.8 cmH(2)O versus 40.8+/-16.4 cmH(2)O, respectively (P=0.005, 95% confidence interval for the mean difference 5.3-23.4 cmH(2)O). Standard chest compressions therefore have the potential of being more effective than the Heimlich manoeuvre for the management of complete airway obstruction by a foreign body in an unconscious patient. Removal of the Heimlich manoeuvre from the resuscitation algorithm for unconscious patients with suspected airway obstruction will also simplify training.

Adult↗
PubMed2000

Arterial blood-gases with 500- versus 1000-ml tidal volumes during out-of-hospital CPR.

The correct tidal volume during cardiopulmonary resuscitation (CPR) is presently debated. While the European Resuscitation Council (ERC) and American Heart Association (AHA) previously recommended a tidal volume of 800-1200 ml, the ERC has recently reduced this to 400-600 ml. In a prospective, randomised study of 17 non-traumatic out-of-hospital cardiac arrest patients intubated and mechanically ventilated 12 min(-1) with 100% oxygen, we have therefore compared arterial blood gases generated with tidal volumes of 500 and 1000 ml. Mean time from cardiac arrest to arrival of the ambulance was 13+/-8 and 14+/-8 min in the two groups, respectively. Arterial blood samples were taken percutaneously 5 and 10-15 min after onset of the mechanical ventilation and analysed instantly. Pa(CO(2)) was significantly higher for a tidal volume of 500 than 1000 ml at both 5 and 10-15 min, 7.48+/-2.23 versus 3.70+/-0.83 kPa (P=0.002) and 7. 45+/-1.19 versus 3.98+/-1.58 kPa (P<0.001). The pH was lower for 500 than 1000 ml at 10-15 min, 7.01+/-0.10 versus 7.20+/-0.17 (P=0.034), with a strong trend in the same direction at 5 min (P=0.06). There was adequate oxygenation with no differences in Pa(O(2)) or BE at any time between the two groups, and no significant differences in any blood gas variables between the 5- and 10-15-min samples. We conclude that arterial normocapnia is not achieved with either tidal volume during advanced life support with non-rebreathing ventilation at 12 min(-1). What ventilation volume is required for CO(2) removal and oxygenation during basic life support with mouth-to-mouth ventilation cannot be extrapolated from the present data. In that situation the risk of gastric inflation, regurgitation and aspiration must also be taken into account.

Aged↗
PubMed1999

Active compression-decompression cardiopulmonary resuscitation: a population-based, prospective randomised clinical trial in out-of-hospital cardiac arrest.

Different mechanical devices have been developed to improve cardiopulmonary resuscitation (CPR). The aim of this study was to evaluate active compression-decompression (ACD) CPR applied by Emergency Medical Service (EMS) in a defined population. The Trondheim region EMS (population 154,000) employs simultaneous paramedic and physician response. Upon decision to treat, patients with cardiac arrest of presumed cardiac origin were allocated to ACD CPR (CardioPump) or standard CPR by drawing a random number tag. Outcome in each patient was determined on a 5 point ordinal scale (no clinical improvement = 1, survival to discharge = 5). In 4 years, CPR was attempted in a total of 431 cardiac arrests, 54 patients (13%) survived to discharge; 302 patients with similar baseline characteristics were randomised. The prevalence of bystander CPR was 57% and the median call-arrival interval 9 min. By intention to treat, the mean score in the standard CPR group was 2.51 and 17/145 patients (12%) survived. The mean score in the ACD CPR group was 2.53 (P = 0.9) and 20/157 patients (13%) survived. Cerebral outcome was similar in the two groups. Among the 145 ACD patients, the technique was successfully applied in 110, found inapplicable in 35 and in seven patients chest compressions were unnecessary. This is the largest, single-centre, randomised, population based study of ACD CPR in out-of-hospital cardiac arrest to date. Even when considering a wider outcome spectrum than crude survival, we found no evidence of clinical benefit. In a quarter of cases ACD CPR was inapplicable, further limiting its potential usefulness.

Aged↗
PubMed1998

Impact of a child first aid wall calendar on lay people's skills and knowledge of infant CPR.

The aim of the study was to evaluate whether mass-mailing of a 12-month wall calendar which focused on child and infant safety and first aid treatment had any educational effect on lay people. The calendar included algorithms for removal of a foreign body from the airways and infant and child CPR. The knowledge and skills in these procedures were tested in two groups using a previously validated check-list before and after the introduction of the calendar. One group received the calendar by mass mailing, free-of-charge. Six months after calendar distribution the mean result for 52 persons tested was 18% correct, not different from the 19% correct for 65 persons tested before calendar distribution. The other group received the calendar as part of an internal company campaign focusing on infant and child safety with a possibility for borrowing a baby manikin, but with no instruction involved. In this group the mean result improved significantly from 27% precalendar (n = 57) to 47% (n = 125) (P < 0.001) 1 week after calendar distribution with a significant reduction to 38% (n = 52) (P = 0.004) 6 months later, still significantly better than precalendar (P = 0.004). Test persons younger than 50 years old scored better than those older than 50 years (39 vs. 22%, P < 0.001), and the test persons scored better if they had been tested previously (44 vs. 35%, P = 0.04) or had practised with a baby manikin (45 vs. 35%, P = 0.02). Whether the test persons had children 0-8 years old or not, did not affect the results. In conclusion the calendar had no educational effect when distributed by mail, but a safety campaign which included distribution of the calendar and a possibility to borrow a manikin had a positive influence on the first aid skills and knowledge of lay people. Mass mailing of CPR or other first aid material free-of-charge does not seem to further the goal of increasing the rate and proficiency of bystander interventions to save lives.

Adult↗
PubMed1998

Effect of different compression--decompression cycles on haemodynamics during ACD-CPR in pigs.

The haemodynamic effects of variations in the relative duration of the compression and active decompression (4 cm/2 cm) during active compression-decompression cardiopulmonary resuscitation (ACD-CPR), 30/70, 50/50 and 70/30, were tested in a randomized cross-over design during ventricular fibrillation in seven anaesthetized pigs (17-23 kg) using an automatic hydraulic chest compression-decompression device. Duty cycles of 50/50 and 70/30 gave significantly higher values than 30/70 for mean carotid blood flow (32 and 36 vs. 21 ml min-1, transit time flow probe, cerebral blood flow (30 and 34 vs. 19, radionuclide microspheres), mean aortic pressure (35 and 41 vs. 29 mmHg) and mean right atrial pressure (24 and 33 vs. 16 mmHg). A higher mean aortic, mean right atrial and mean left ventricular pressure for 70/30 were the only significant differences between 50/50 and 70/30. There were no differences in myocardial blood flow (radionuclide microspheres) or coronary perfusion pressure (CPP, aortic-right atrial pressure) between the three different duty cycles. CPP was positive in both the early and late compression period and during the whole decompression period. The expired CO2 was significantly higher with 70/30 than 30/70 during the compression phase of ACD-CPR. Beyond that no significant differences in the expired CO2 levels were observed. In conclusion a reduction of the compression period to 30% during ACD-CPR reduced the cerebral circulation, the mean aortic and right atrial pressures with no effect on the myocardial blood flow of varying the compression-decompression cycle.

Animals↗
PubMed1998

Improved haemodynamics with increased compression-decompression rates during ACD-CPR in pigs.

The haemodynamic effects of variations in the compression-decompression frequency, 60, 90 and 120 min(-1) during ACD-CPR, were tested in a randomized cross-over design during ventricular fibrillation (VF) in 12 anaesthetized pigs (17-22 kg) using an automatic hydraulic chest compression-decompression device. There were significant increases with increasing frequency for mean (+/- S.D.) carotid blood flow (17 +/- 5, 25 +/- 9 and 36 +/- 12 ml min(-1), transit time flow probe), cerebral blood flow (17 +/- 7, 30 +/- 17 and 40 +/- 13 ml min(-1) 100 g(-1), radionuclide microspheres) and mean aortic pressure (34 +/- 8, 37 +/- 10 and 43 +/- 7 mmHg), respectively. Myocardial blood flow (radionuclide microspheres) and diastolic coronary perfusion pressure, CPP, increased significantly from 60 to 90 min(-1) with no further significant increase to 120 min(-1) (28 +/- 13, 46 +/- 23 and 49 +/- 19 ml min(-1) 100 g(-1) and 25 +/- 8, 31 +/- 11 and 32 +/- 9 mmHg, respectively). Renal and hepatic blood flow also increased with increasing rate. No significant differences in the expired CO2 levels were observed. In conclusion increasing the compression-decompression frequency from 60 to 90 and 120 min(-1) improved the haemodynamics during ACD-CPR in a pig model with VF.

Analysis of Variance↗
PubMed1997

Intubation with laryngoscope versus transillumination performed by paramedic students on manikins and cadavers.

Seventeen paramedic students, all of whom are novice intubators, performed laryngoscopic and Trachlight intubation after supervised training for 90 min on two manikins (Laerdal, AMBU) and 30 min on cadavers. A maximum of two intubation attempts lasting a maximum 30 s each were permitted on each manikin and the cadaver. The time for confirming tube placement by auscultation and securing the tube was added. Laryngoscopic intubation was successful on cadavers and both manikins in 94-100% of the trials. Intubation with the Trachlight was 100% successful in the Laerdal manikin, but significantly lower than with the laryngoscope in the AMBU manikin (65%), and in cadavers (50%). The mean intubation time was significantly longer (30-44 s) with the Trachlight compared with laryngoscopic intubation (10-23 s) in both manikins and cadavers. The present results do not indicate that intubation with the Trachlight is an improvement upon laryngoscopic intubation for novices.

Allied Health Personnel↗
PubMed1997

Active compression-decompression cardiopulmonary resuscitation (ACD-CPR) compared with standard CPR in a manikin model--decompression force, compression rate, depth and duration.

During active compression-decompression cardiopulmonary resuscitation (ACD-CPR), the rescuer applies traction to the chest between compressions. Under experimental conditions, cardiac output increases, possibly through accentuated intrathoracal pressure fluctuations. ACD-CPR requires specific training and may be more complex to perform than standard CPR. The aim of this study was to characterize ACD-CPR performance compared with standard CPR by emergency care providers; in terms of decompression force, compression rate, depth and duration. Thirty-three ambulance paramedics were studied while performing standard CPR and ACD-CPR with the Ambu Cardiopump on a specially designed transducer-equipped manikin 9 months following initial training. The order of CPR performance was determined randomly by cross-over design. Performance data were recorded by a computer. The 2-min average active decompression force was 9.3 kg (interquartile range 2.5-15.3 kg) and six subjects (18%) met the manufacturers recommendation of 10-15 kg. External chest compression (ECC) rate decreased from 85 (70-101) to 76 (63-88) min-1 (P < 0.001), ECC depth decreased from 54 (50-58) to 45 (39-48) mm (P < 0.001) and compression duration from 40 (35-45) to 31% (28-33%) (P < 0.001) upon change from standard CPR to ACD-CPR. We conclude that the recommended level of decompression force was achieved by less than one fifth of study subjects. ACD-CPR when compared with standard CPR causes a consistent and significant reduction of compression rate, depth and duration. These are all factors of possible clinical significance. Training in ACD-CPR should address this issue, with special emphasis on optimal decompression force and ECC rate.

Adult↗
PubMed1997

Quality of mechanical, manual standard and active compression-decompression CPR on the arrest site and during transport in a manikin model.

The quality of mechanical CPR (M-CPR) was compared with manual standard CPR (S-CPR) and active compression-decompression CPR (ACD-CPR) performed by paramedics on the site of a cardiac arrest and during manual and ambulance transport. Each technique was performed 12 times on manikins using teams from a group of 12 paramedic students with good clinical CPR experience using a random cross-over design. Except for some lost ventilations the CPR effort using the mechanical device adhered to the European Resuscitation Council guidelines, with an added time requirement of median 40 s for attaching the device compared with manual standard CPR. Throughout the study, in comparison with mechanical CPR the quality of CPR with either manual method was significantly worse. In particular, there were considerable individual variations during stretcher transport. With S-CPR and ACD-CPR the median compression times were 38 and 31%, significantly lower than the recommended 50%, and 46-98% of the decompression efforts with ACD-CPR were too weak, particularly during transport on the stairs. With both manual methods, there were no significant differences in the CPR effort between the site of the arrest and the ambulance transport. However, compression rates were reduced and became more erratic during stretcher transport to the ambulance. When walking horizontally, a median of 19% of S-CPR compressions and 84% of ACD-CPR compressions were to weak. On the stairs, 68% of S-CPR compressions and 100% of ACD-CPR compressions were too weak. In conclusion, when evaluated on a manikin, in comparison with manual standard and ACD-CPR, mechanical CPR adhered more closely to ERC guidelines. This was particularly true when performing CPR during transport on a stretcher.

Cardiopulmonary Resuscitation↗
PubMed1996

Effects of various degrees of compression and active decompression on haemodynamics, end-tidal CO2, and ventilation during cardiopulmonary resuscitation of pigs.

UNLABELLED: The effects of various degrees of compression and active decompression during cardiopulmonary resuscitation were tested in a randomized cross-over-design during ventricular fibrillation in eight pigs using an automatic hydraulic chest compression device. Compared with 4/0 (compression/decompression in cm), mean carotid arterial blood flow rose by 60% with 5/0, by 90% with 4/2 and 4/3, and 105% with 5/2. Two cm active decompression increased mean brain and myocardial blood flow by 53% and 37%, respectively, as compared with 4/0. Increasing standard compression from 4 to 5 cm caused no further increase in brain or heart tissue blood flow whether or not combined with active decompression. Tissue blood flow remained unchanged or decreased when active decompression (4/3) caused that 50% of the pigs were lifted from the table due to the force required. Myocardial blood flow was reduced with 5/0 vs. 4/0 despite no reduction in end decompression coronary perfusion pressure ((aortic-right atrial pressure) (CPP), (7 +/- 8 mmHg with 4/0, 14 +/- 11 mmHg with 5/0)(NS)). End decompression CPP increased by 186% with 4/2 vs. 4/0, by 200% with 4/3, and by 300% with 5/2. Endo-tracheal partial pressure of CO2 was significantly increased during the compression phase of active decompression CPR compared with standard CPR. Active decompression CPR generated an significantly increased ventilation compared with standard CPR. CONCLUSION: Carotid and tissue blood flow, ventilation, and CPP increase with 2 cm of active decompression. An attempt to further increase the level of active decompression or increasing the compression depth from 4 to 5 cm did not improve organ blood flow.

Animals↗