A Comparison of Non-Invasive Blood Pressure Measurement Strategies with Intra-Arterial Measurement.

INTRODUCTION: It is difficult to obtain an accurate blood pressure (BP) measurement, especially in the prehospital environment. It is not known fully how various BP measurement techniques differ from one another. STUDY OBJECTIVE: The study hypothesized that there are differences in the accuracy of various non-invasive blood pressure (NIBP) measurement strategies as compared to the gold standard of intra-arterial (IA) measurement. METHODS: The study enrolled adult intensive care unit (ICU) patients with radial IA catheters placed to measure radial intra-arterial blood pressure (RIBP) as a part of their standard care at a large, urban, tertiary-care Level I trauma center. Systolic blood pressure (SBP) was taken by three different NIBP techniques (oscillometric, auscultated, and palpated) and compared to RIBP measurements. Data were analyzed using the paired t-test with dependent samples to detect differences between RIBP measurements and each NIBP method. The primary outcome was the difference in RIBP and NIBP measurement. There was also a predetermined subgroup analysis based on gender, body mass index (BMI), primary diagnosis requiring IA line placement, and current vasoactive medication use. RESULTS: Forty-four patients were enrolled to detect a predetermined clinically significant difference of 5mmHg in SBP. The patient population was 63.6% male and 36.4% female with an average age of 58.4 years old. The most common primary diagnoses were septic shock (47.7%), stroke (13.6%), and increased intracranial pressure (ICP; 13.6%). Most patients were receiving some form of sedation (63.4%), while 50.0% were receiving vasopressor medication and 31.8% were receiving anti-hypertensive medication. When compared to RIBP values, only the palpated SBP values had a clinically significant difference (9.88mmHg less than RIBP; P < .001). When compared to RIBP, the oscillometric and auscultated SBP readings showed statistically but not clinically significant lower values. The palpated method also showed a clinically significant lower SBP reading than the oscillometric method (5.48mmHg; P < .001) and the auscultated method (5.06mmHg; P < .001). There was no significant difference between the oscillometric and auscultated methods (0.42mmHg; P = .73). CONCLUSION: Overall, NIBPs significantly under-estimated RIBP measurements. Palpated BP measurements were consistently lower than RIBP, which was statistically and clinically significant. These results raise concern about the accuracy of palpated BP and its pervasive use in prehospital care. The data also suggested that auscultated and oscillometric BP may provide similar measurements.

Altitude-Related Change in Endotracheal Tube Cuff Pressures in Helicopter EMS.

INTRODUCTION: Over-inflation of endotracheal tube (ETT) cuffs has the potential to lead to scarring and stenosis of the trachea.1, 2,3, 4 The air inside an ETT cuff is subject to expansion as atmospheric pressure decreases, as happens with an increase in altitude. Emergency medical services helicopters are not pressurized, thereby providing a good environment for studying the effects of altitude changes ETT cuff pressures. This study aims to explore the relationship between altitude and ETT cuff pressures in a helicopter air-medical transport program. METHODS: ETT cuffs were initially inflated in a nonstandardized manner and then adjusted to a pressure of 25 cmH2O. The pressure was again measured when the helicopter reached maximum altitude. A final pressure was recorded when the helicopter landed at the receiving facility. RESULTS: We enrolled 60 subjects in the study. The mean for initial tube cuff pressures was 70 cmH2O. Maximum altitude for the program ranged from 1,000-3,000 feet above sea level, with a change in altitude from 800-2,480 feet. Mean cuff pressure at altitude was 36.52 ± 8.56 cmH2O. Despite the significant change in cuff pressure at maximum altitude, there was no relationship found between the maximum altitude and the cuff pressures measured. CONCLUSION: Our study failed to demonstrate the expected linear relationship between ETT cuff pressures and the maximum altitude achieved during typical air-medical transportation in our system. At altitudes less than 3,000 feet above sea level, the effect of altitude change on ETT pressure is minimal and does not require a change in practice to saline-filled cuffs.

Familial Anaphylaxis after Silkworm Ingestion.

Herein, we present a case of anaphylaxis in multiple family members after ingesting silkworms, an Asian delicacy. While food allergies, including anaphylaxis are unfortunately common, there are no previous reports of multiple family members suffering an anaphylactic reaction after eating silkworms. In addition, both family members required multiple doses of epinephrine and eventually an epinephrine infusion to improve their blood pressures. All interventions, including the epinephrine infusions, were started by emergency medical services (EMS) with on-line medical direction. Both the reaction and the required treatment are not extensively documented in the medical literature.

Pitfalls of intranasal naloxone.

We present a case of failed prehospital treatment of fentanyl induced apnea with intranasal (IN) naloxone. While IN administration of naloxone is becoming more common in both lay and pre-hospital settings, older EMS protocols utilized intravenous (IV) administration. Longer-acting, higher potency opioids, such as fentanyl, may not be as easily reversed as heroin, and studies evaluating IN administration in this population are lacking. In order to contribute to our understanding of the strengths and limitations of IN administration of naloxone, we present a case where it failed to restore ventilation. We also describe peer reviewed literature that supports the use of IV naloxone following heroin overdose and explore possible limitations of generalizing this literature to opioids other than heroin and to IN routes of administration.