Jaehoon Oh

The use of dual accelerometers improves measurement of chest compression depth

BACKGROUND Chest compression (CC) feedback devices are used to perform CC measurements effectively and accurately on patients in hospital beds. However, these devices do not take account of the compression of the mattress, which results in overestimation of CC depth. In this study, we propose a new method using two accelerometers to overcome this limitation and thus measure compression depth more accurately when performing cardiopulmonary resuscitation (CPR) on patients. METHOD One accelerometer was placed on the manikins sternum (a1), and the other between the manikins back and the mattress (a2). The compression depth was calculated by integrating the acceleration twice using a digital signal processing technique. We compared CC depth from dual accelerometers and single accelerometer (a1) on the foam and inflated air mattress with eight CPR providers. RESULT When CC was done on a manikin lying on the floor, there was no significant difference between measurement techniques (p>0.05). When CC was done on a manikin lying on the foam and inflated air mattress supporting system, our method significantly improved the estimation of CC depth, irrespective of the presence or absence of a backboard (p<0.001). CONCLUSION Measuring CC depth using two accelerometers is more effective than using one in increasing the accuracy of CC depth estimation when CPR is performed on the foam and inflated air mattress, regardless of the presence or absence of a backboard.

Videographic Analysis of Glottic View With Increasing Cricoid Pressure Force

STUDY OBJECTIVE Cricoid pressure may negatively affect laryngeal view and compromise airway patency, according to previous studies of direct laryngoscopy, endoscopy, and radiologic imaging. In this study, we assess the effect of cricoid pressure on laryngeal view with a video laryngoscope, the Pentax-AWS. METHODS This cross-sectional survey involved 50 American Society of Anesthesiologists status I and II patients who were scheduled to undergo elective surgery. The force measurement sensor for cricoid pressure and the video recording system using a Pentax-AWS video laryngoscope were newly developed by the authors. After force and video were recorded simultaneously, 11 still images were selected per 5-N (Newton; 1 N = 1 kg·m·s(-2)) increments, from 0 N to 50 N for each patient. The effect of cricoid pressure was assessed by relative percentage compared with the number of pixels on an image at 0 N. RESULTS Compared with zero cricoid pressure, the median percentage of glottic view visible was 89.5% (interquartile range [IQR] 64.2% to 117.1%) at 10 N, 83.2% (IQR 44.2% to 113.7%) at 20 N, 76.4% (IQR 34.1% to 109.1%) at 30 N, 51.0% (IQR 21.8% to 104.2%) at 40 N, and 47.6% (IQR 15.2% to 107.4%) at 50 N. The number of subjects who showed unworsened views was 20 (40%) at 10 N, 17 (34%) at 20 and 30 N, and 13 (26%) at 40 and 50 N. CONCLUSION Cricoid pressure application with increasing force resulted in a worse glottic view, as examined with the Pentax-AWS Video laryngoscope. There is much individual difference in the degree of change, even with the same force. Clinicians should be aware that cricoid pressure affects laryngeal view with the Pentax-AWS and likely other video laryngoscopes.

A novel method to decrease mattress compression during CPR using a mattress compression cover and a vacuum pump

BACKGROUND Mattress compression causes feedback devices to over-estimate the chest compression depth measurement during CPR. We propose a novel method to decrease the mattress compression using a vinyl cover. This mattress compression cover encloses the foam mattress and is compressed by a vacuum pump immediately prior to performing CPR. METHODS Nine CPR providers performed chest compressions on manikins placed on a conventional foam mattress on a bed frame (surface CONV), a backboard and foam mattress on a bed frame (surface BB), and a foam mattress, compressed with a vacuum pump, on a bed frame (surface VAC). Dual accelerometers were used to simultaneously measure the mattress compression and chest compression depths. RESULTS The mattress compression depth levels decreased from 14.9 mm (SD 1.4 mm) on surface CONV to 7.0 mm (SD 0.6 mm) on surface VAC (p<0.001) whereas 14.0 mm (SD 1.3 mm) on surface BB. The total compression depth was 65.4 mm (SD 3.8 mm) on surface CONV, and 58.3 mm (SD 3.0 mm) on surface VAC (p<0.001). CONCLUSION Using a mattress compression cover and a vacuum pump appears to increase the rigidity of the mattress and allow for efficient chest compressions. This novel method could decrease the mattress compression depth and increase the efficiency of chest compression during CPR in hospitals.

Smartwatches as chest compression feedback devices: A feasibility study

BACKGROUND Recently, there have been attempts to use smartphones and smartwatches as the feedback devices to improve the quality of chest compressions. In this study, we compared chest compression depth feedback accuracy between a smartphone and a smartwatch in a hands-only cardiopulmonary resuscitation scenario, using a manikin with a displacement sensor system. METHODS Ten basic life support providers participated in this study. Guided by the chest compression depths displayed on the monitor of a laptop, which received data from the manikin, each participant performed 2min of chest compressions for each target depth (35mm and 55mm) on a manikin while gripping a smartphone and wearing a smartwatch. Participants had a rest of 1h between the instances, and the first target depth was set at random. Each chest compression depth data value from the smartphone and smartwatch and a corresponding reference value from the manikin with the displacement system were recorded. To compare the accuracy between the smartphone and smartwatch, the errors, expressed as the absolute of the differences between the reference and each device, were calculated. RESULTS At both target depths, the error of the smartwatch were significantly smaller than that of the smartphone (the errors of the smartphone vs. smartwatch at 35mm: 3.4 (1.3) vs. 2.1 (0.8) mm; p=0.008; at 55mm: 5.3 (2.8) vs. 2.3 (0.9) mm; p=0.023). CONCLUSION The smartwatch-based chest compression depth feedback was more accurate than smartphone-based feedback.

Correlation between Physical Features of Elementary School Children and Chest Compression Depth

Introduction The height and body weight of 6th grade elementary school children may have influence on chest compression. Materials & methods In accordance with the 2005 American Heart Association guidelines and 2006 Korean Association of CardioPulmonary Resuscitation (CPR) guidelines, a 25-minute audiovisual presentation and practical demonstration of CPR were presented by the researchers and assistants. The assistants supervised and corrected the practical performance of the students who performed 5 cycles of CPR (2 minutes each) with the aid of the Laerdal Resusci® Anne SkillReporter™. The students then carried out another 5 cycles of CPR (2 minutes each) using the skill reporter; and a short report was printed. Results The correlation coefficient between body weight and chest compression was 0.467 (p=0.000), and the correlation coefficient between height and chest compression was 0.309 (p=0.009). The intercept between body weight and chest compression was 21.763 (p=0.000), and the slope was 0.324 (p=0.000). Student height showed no linear correlation with chest compression depth. Conclusions The body weight of 6th grade elementary school children showed moderate correlation with chest compression depth. A minimal body weight of 50 kg is required to attain a standard chest compression depth of 38 mm. With improved training, some students with body weight less than 50 kg may also achieve satisfactory performance of CPR.

Comparisons of the Pentax-AWS, Glidescope, and Macintosh Laryngoscopes for Intubation Performance during Mechanical Chest Compressions in Left Lateral Tilt: A Randomized Simulation Study of Maternal Cardiopulmonary Resuscitation

Purpose. Rapid advanced airway management is important in maternal cardiopulmonary resuscitation (CPR). This study aimed to compare intubation performances among Pentax-AWS (AWS), Glidescope (GVL), and Macintosh laryngoscope (MCL) during mechanical chest compression in 15° and 30° left lateral tilt. Methods. In 19 emergency physicians, a prospective randomized crossover study was conducted to examine the three laryngoscopes. Primary outcomes were the intubation time and the success rate for intubation. Results. The median intubation time using AWS was shorter than that of GVL and MCL in both tilt degrees. The time to visualize the glottic view in GVL and AWS was significantly lower than that of MCL (all P < 0.05), whereas there was no significant difference between the two video laryngoscopes (in 15° tilt, P = 1; in 30° tilt, P = 0.71). The progression of tracheal tube using AWS was faster than that of MCL and GVL in both degrees (all P < 0.001). Intubations using AWS and GVL showed higher success rate than that of Macintosh laryngoscopes. Conclusions. The AWS could be an appropriate laryngoscope for airway management of pregnant women in tilt CPR considering intubation time and success rate.

Proper target depth of an accelerometer-based feedback device during CPR performed on a hospital bed: a randomized simulation study

PURPOSE Feedback devices are used to improve chest compression (CC) quality related to survival rates in cardiac arrest. However, several studies have shown that feedback devices are not sufficiently reliable to ensure adequate CC depth on soft surfaces. Here, we determined the proper target depth of feedback (TDF) using an accelerometer during cardiopulmonary resuscitation in hospital beds. METHODS In prospective randomized crossover study, 19 emergency physicians performed CCs for 2 minutes continuously on a manikin in 2 different beds with 3 TDFs (5, 6, and 7 cm). We measured CC depth, the proportion of accurate compression depths, CC rate, the proportion of incomplete chest decompressions, the velocity of CC (CC velocity), the proportion of time spent in CC relative to compression plus decompression (duty cycle), and the time spent in CC (CC time). RESULTS Mean (SD) CC depths at TDF 5, 6, and 7 were 45.42 (5.79), 52.68 (4.18), and 58.47 (2.48) on one bed and 46.26 (4.49), 53.58 (3.15), and 58.74 (2.10) mm on the other bed (all P<.001), respectively. The proportions of accurate compression depths and CC velocity at TDF 5, 6, and 7 differed significantly according to TDF on both beds (all P<.001).The CC rate, CC time, and proportion of incomplete chest decompression did not differ on both beds (all P>.05). The duty cycle differed significantly on only B2. CONCLUSIONS The target depth of the real-time feedback device should be at least 6 cm but should not exceed 7 cm for optimal CC on patients on hospital beds.

Comparison of the Pentax Airwayscope, Glidescope Video Laryngoscope, and Macintosh Laryngoscope During Chest Compression According to Bed Height.

Abstract We aimed to investigate whether bed height affects intubation performance in the setting of cardiopulmonary resuscitation and which type of laryngoscope shows the best performance at each bed height. A randomized crossover manikin study was conducted. Twenty-one participants were enrolled, and they were randomly allocated to 2 groups: group A (n = 10) and group B (n = 11). The participants underwent emergency endotracheal intubation (ETI) using the Airwayscope (AWS), Glidescope video laryngoscope, and Macintosh laryngoscope in random order while chest compression was performed. Each ETI was conducted at 2 levels of bed height (minimum bed height: 68.9 cm and maximum bed height: 101.3 cm). The primary outcomes were the time to intubation (TTI) and the success rate of ETI. The P value for statistical significance was set at 0.05 and 0.017 in post-hoc test. The success rate of ETI was always 100% regardless of the type of laryngoscope or the bed height. TTI was not significantly different between the 2 bed heights regardless of the type of laryngoscope (all P > 0.05). The time for AWS was the shortest among the 3 laryngoscopes at both bed heights (13.7 ± 3.6 at the minimum bed height and 13.4 ± 4.7 at the maximum bed height) (all P < 0.017). The TTI of Glidescope video laryngoscope was not significantly shorter than that of Macintosh laryngoscope at the minimum height (17.6 ± 4.0 vs 19.6 ± 4.8; P = 0.02). The bed height, whether adjusted to the minimum or maximum setting, did not affect intubation performance. In addition, regardless of the bed height, the intubation time with the video laryngoscopes, especially AWS, was significantly shorter than that with the direct laryngoscope during chest compression.

Effectiveness of chest compression feedback during cardiopulmonary resuscitation in lateral tilted and semirecumbent positions: a randomised controlled simulation study

Feedback devices have been shown to improve the quality of chest compression during cardiopulmonary resuscitation for patients in the supine position, but no studies have reported the effects of feedback devices on chest compression when the chest is tilted. Basic life support‐trained providers were randomly assigned to administer chest compressions to a manikin in the supine, 30° left lateral tilt and 30° semirecumbent positions, with or without the aid of a feedback device incorporated into a smartphone. Thirty‐six participants were studied. The feedback device did not affect the quality of chest compressions in the supine position, but improved aspects of performance in the tilted positions. In the lateral tilted position, the median (IQR [range]) chest compression rate was 99 (99–100 [96–117]) compressions.min−1 with and 115 (95–128 [77–164]) compressions.min−1 without feedback (p = 0.05), and the proportion of compressions of correct depth was 55 (0–96 [0–100])% with and 1 (0–30 [0–100])% without feedback (p = 0.03). In the semirecumbent position, the proportion of compressions of correct depth was 21 (0–87 [0–100])% with and 1 (0–26 [0–100])% without feedback (p = 0.05). Female participants applied chest compressions at a more accurate rate using the feedback device in the lateral tilted position but were unable to increase the chest compression depth, whereas male participants were able to increase the force of chest compression using the feedback device in the lateral tilted and semirecumbent positions. We conclude that a feedback device improves the application of chest compressions during simulated cardiopulmonary resuscitation when the chest is tilted.

Chest compression with kneeling posture in hospital cardiopulmonary resuscitation: A randomised crossover simulation study

We suggest an alternative chest compression (CC) in kneeling posture using a ‘kneeling stool’ on which the performer kneels beside the patient on a bed in‐hospital. In kneeling posture, we can maintain high quality cardiopulmonary resuscitation (CPR) without the bed height adjustment, which is necessary and inconvenient in standing posture.