Ultrasound guided chest compressions during cardiopulmonary resuscitation

Initiation of Invasive Arterial Pressure Monitoring by Critical Care Transport Crews

Noninvasive blood pressure monitoring is convenient in the prehospital setting, but its use in the critically ill patient should be carefully considered given documented inaccuracies. Countless therapeutic patient interventions are based on blood pressure parameters, and the prehospital paramedic, nurse, and physician should strongly consider the use of invasive blood pressure monitoring, especially during critical care transport. Radial artery cannulation for arterial blood pressure monitoring is a safe and effective procedure that can reasonably be performed in the prehospital setting by both physicians and nonphysicians. Critical care transport teams should consider clinical guidelines that outline indications and training to safely implement this as a clinical skill.

The effect of high-dose intramuscular epinephrine on the recovery of spontaneous circulation in an asphyxia-induced cardiac arrest rat model

BACKGROUND

Obtaining vascular access can be challenging during resuscitation following cardiac arrest, and it is particularly difficult and time-consuming in paediatric patients. We aimed to compare the efficacy of high-dose intramuscular (IM) versus intravascular (IV) epinephrine administration with regard to the return of spontaneous circulation (ROSC) in an asphyxia-induced cardiac arrest rat model.

METHODS

Forty-five male Sprague-Dawley rats were used for these experiments. Cardiac arrest was induced by asphyxia, and defined as a decline in mean arterial pressure (MAP) to 20 mmHg. After asphyxia-induced cardiac arrest, the rats were randomly allocated into one of 3 groups (control saline group, IV epinephrine group, and IM epinephrine group). After 540 s of cardiac arrest, cardiopulmonary resuscitation was performed, and IV saline (0.01 cc/kg), IV (0.01 mg/kg, 1:100,000) epinephrine or IM (0.05 mg/kg, 1:100,000) epinephrine was administered. ROSC was defined as the achievement of an MAP above 40 mmHg for more than 1 minute. Rates of ROSC, haemodynamics, and arterial blood gas analysis were serially observed.

RESULTS

The ROSC rate (61.5%) of the IM epinephrine group was less than that in the IV epinephrine group (100%) but was higher than that of the control saline group (15.4%) (log-rank test). There were no differences in MAP between the two groups, but HR in the IM epinephrine group (beta coefficient = 1.02) decreased to a lesser extent than that in the IV epinephrine group with time.

CONCLUSIONS

IM epinephrine induced better ROSC rates compared to the control saline group in asphyxia-induced cardiac arrest, but not compared to IV epinephrine. The IM route of epinephrine administration may be a promising option in an asphyxia-induced cardiac arrest.

Use of a Simple Ultrasound Device to Identify the Optimal Area of Compression for Out-of-Hospital Cardiac Arrest

Background Despite automated defibrillation and compression-first resuscitation, out-of-hospital cardiac arrest (OHCA) survival remains low. Resuscitation guidelines recommend that chest compressions should be done over the lower half of the sternum, but evidence indicates that this is often associated with outflow obstruction. Emerging studies suggest that compression directly over the left ventricle (LV) may improve survival and outcomes, but rapid and reliable localization of the LV is a major obstacle for those first responding to OHCA. This study aimed to determine if a simplified, easy-to-use ultrasound device (bladder scanner) can reliably locate the heart when applied over the intercostal spaces of the anterior thorax in supine patients. Furthermore, we sought to describe the association between largest scan volumes and underlying cardiac anatomy with particular attention to the long axis of the LV. Methodology We recruited healthy male and female volunteers over 40 years of age. Using a bladder scanner to evaluate the left sternal border and mid-clavicular lines, we determined the maximal scan volumes at 10 intercostal spaces for each participant. Cardiac ultrasound was then used to evaluate the corresponding underlying cardiac anatomy and determine the area overlying the long-axis view of the LV. Descriptive statistics (means with standard deviations [SD], medians with interquartile ranges, and frequencies with proportions) were used to quantify demographic information, typical scan volumes across the chest, the frequencies of the best long-axis LV view location. This was then repeated for left sternal border assessments only. Kappa was determined when evaluating agreement between the largest left sternal border scan volume and the best long-axis LV view location. Results The long-axis LV was the predominant structure underlying the largest scan volume in 39/51 (76.5%) patients. When limited to left sternal border volumes only, the long axis of the LV was underlying the maximum volume intercostal space in 46/51 (90.2%; 95% confidence interval [CI]: 78.6%, 96.7%). The largest left sternal border scan volumes were located over the best long-axis LV view in 39/51 (76.5%, 95% CI: 62.5%, 87.2%) of the study participants with a Kappa statistic of 0.68 (95% CI: 0.52, 0.84; p < 0.0001).  Conclusions In this cross-sectional study of healthy volunteers, an easy-to-use ultrasound device (bladder scanner) was able to reliably localize the heart. Largest scan volumes over the left sternal border showed substantial agreement with the intercostal space overlying the long axis of the LV. Further investigations are warranted to determine if such localization is reliable in cardiac arrest patients.

Ultrasound-Guided Chest Compressions in Out-of-Hospital Cardiac Arrests

BACKGROUND

There is a significant variability in survival rates for cardiopulmonary resuscitation (CPR) in out of-hospital cardiac arrest (OHCA), and some data indicate that ultrasound improves CPR.

OBJECTIVES

We evaluated the feasibility of ultrasound for monitoring chest compressions in OHCA.

METHODS

We planned a prospective study in patients with an ultrasound-integrated CPR for OHCA. Chest compressions were performed on the intermammillary line (IML), but the position was changed according to the quality of the heart squeezing, evaluated by ultrasound. End-tidal carbon dioxide (ETCO₂) was used as the control parameter. Then we compared the area with the highest squeezing with the position of the heart in the chest computed tomography (CT) scans of 20 hospitalized patients.

RESULTS

Chest compressions were good, partial, and inadequate on the IML in 58.4%, 48.9%, and 2.8% of cases, respectively. These percentages were 75%, 25%, and 0% after these modifications: none (47.2%), increased depth (8.3%), hands moved on the lower third of the sternum (27.8%), on left parasternal line of the lower part of the sternum (13.9%), and on the center of the sternum (1 case). Accordingly, ETCO₂ improved significantly (20.37 vs. 37.10, p < 0.0001). The CT scans showed that the larger biventricular area (BVA) was under the parasternal line of the lower third of the sternum, and the mean distance IML-BVA was 5.7 cm.

CONCLUSIONS

Our study has demonstrated that CPR in OHCA can be improved using ultrasound and changing the position of the hands. This finding was connected with the ETCO₂ and confirmed by chest CT scans.