Correspondence The views expressed herein are those of the authors and do not reflect the official policy or position of Brooke Army Medical Center, the US Army Medical Department, the US Army Office of the Surgeon General, the Department of the Army and Department of Defense, or the US government. 1. Bebarta VS, Tanen DA, Boudreau S, et al. Intravenous cobinamide versus hydroxocobalamin for acute treatment of severe cyanide poisoning in a swine (Sus scrofa) model. Ann Emerg Med. 2014;64:612-619. 2. Brenner M, Mahon SB, Lee J, et al. Comparison of cobinamide to hydroxocobalamin in reversing cyanide physiologic effects in rabbits using diffuse optical spectroscopy monitoring. J Biomed Opt. 2010;15:017001. 3. Chan A, Balasubramanian M, Blackledge W, et al. Cobinamide is superior to other treatments in a mouse model of cyanide poisoning. Clin Toxicol (Phila). 2010;48:709-717.
In reply: We thank Dr. Schapira and his colleagues for their letter. In regard to the cobinamide dose, several aspects of the drug allow a lower dose than hydroxocobalamin. In addition to cobinamide binding 2 cyanide molecules, it has a much higher affinity for cyanide than hydroxocobalamin, is more water soluble, and is taken up by cells faster. These and other factors likely contribute to the effective dose of cobinamide that is approximately 20% that of hydroxocobalamin. In addition, we have been successful with intraosseous and intramuscular administration of cobinamide to rescue animals from cyanideinduced apnea (unpublished data). In regard to Figured 3D, we apologize that the lines are indeed mislabeled, ie, the cobinamide data are the dashed line, whereas the hydroxocobalamin data are the solid line. As we state in the “Results,” these differences in plasma cyanide concentrations between the 2 groups were not significant, and we attribute the higher cyanide concentrations in the cobinamide-treated animals to be from higher cobinamide binding to plasma proteins. Although additional doses of either antidote might be needed in a longer experiment, the cyanide concentrations were undetectable at 60 minutes in the cobinamide group, similar to the hydroxocobalamin group. In addition, in preliminary experiments with 4 hours of observation, additional doses of cobinamide were not needed. In our model, as in other animal models, apnea is an early effect of cyanide and is followed by hypotension and then cardiac arrest. This pattern has been reported in humans as well. We agree that evaluation of the adverse neurologic effects of cyanide is important in individuals who survive. To this end, we are currently conducting a survival study in a similar model to evaluate neurologic function in surviving animal and neuropathologic findings on necropsy. Lt Col Vikhyat S. Bebarta, MD, USAF Medical Toxicology San Antonio Military Medical Center San Antonio, TX Volume 65, no. 2 : February 2015
David A. Tanen, MD David Geffen School of Medicine at UCLA Harbor-UCLA Medical Center Torrance, CA Susan Boudreau, RN, BSN Maria Castaneda, BS, MS Department of Emergency Medicine San Antonio Military Medical Center San Antonio, TX Lee A. Zarzabal, MS Medpro Technologies San Antonio, TX Toni Vargas, PA-C Office of the Chief Scientist/59th MDW Wilford Hall Ambulatory Surgical Center San Antonio, TX Gerry R. Boss, MD University of California San Diego, CA http://dx.doi.org/10.1016/j.annemergmed.2014.10.014
Funding and support: By Annals policy, all authors are required to disclose any and all commercial, financial, and other relationships in any way related to the subject of this article as per ICMJE conflict of interest guidelines (see www. icmje.org). The authors have stated that no such relationships exist. The study was funded by the US Air Force Office of the Surgeon General (SG5, FWH20100170A) and the CounterACT Program, Office of the Director, National Institutes of Health and the National Institutes of Neurological Disorders and Stroke, grant U01NS058030. No other funding was used. The views expressed in this article are those of the authors and do not reflect the official policy or position of the Department of the US Air Force, Department of Defense, or the US government.
Auscultation Without Contamination: A Solution for Stethoscope Use With Personal Protective Equipment To the Editor: The Centers for Disease Control and Prevention (CDC) recently released more stringent guidelines1 for how health care providers can best protect themselves from Ebola exposure while putting on and removing personal protective equipment. These guidelines include the routine use of surgical hoods, full face shields, and N-95 respirators or powered air purifying respirators. Hospitals are now Annals of Emergency Medicine 235
Correspondence scrambling to ensure that their providers are properly trained and provisioned. Having participated in mandatory training in donning and doffing personal protective equipment, I think it unlikely that one can safely use a traditional stethoscope in the proposed Ebola care environment, especially if one is a biocontainment novice. Neither the CDC protocol nor the Emory University protocols2 discusses how to safely use a stethoscope without compromising the protective barrier. Thinklabs (Centennial, CO) has developed a digital stethoscope, which processes the sound picked up by the electronic diaphragm into a digital signal and transmits that signal to high-quality earphones or headphones. University of Nebraska providers successfully used this digital stethoscope to evaluate Ebola patients by inserting disposable ear buds before donning face shield and mask or respirator and then snaking the cable out below the impermeable gown.3,4 Subsequent ear bud removal required yanking the cable to displace the ear buds. There are 2 major disadvantages inherent in this approach: first, occlusion of the ear canals compromises communication with the patient and among providers until the ear buds are yanked out, and second, ear bud removal prevents additional auscultation until the next personal protective equipment–donning cycle.
I propose a better solution: the Thinklabs One digital stethoscope connected by its headphone output jack directly to a small Bluetooth transmitter (Avantree, Shenzhen, China) through a male-to-male 3.5-mm connector (Figure). The digital signal can then be transmitted to bone-conduction Bluetooth headphones (Blues2; Aftershokz, East Syracuse, NY). Such headphones transmit sounds to the middle ear by bone conduction and leave the external ear canal unobstructed. I have used such a setup in the emergency department for more than 2 months and find that I have excellent sound quality of heart and lung sounds while still being able to converse with patients and staff. In a proofof-concept test, I was able to perform auscultation remotely from 30 m away. I did have to perform some minor nonbillable surgery on the 3.5-mm connector so that it would fit into the recessed headphone jack of the digital stethoscope; this took about 2 minutes with a #11 size scalpel. A similar setup could provide significant advantages over conventional stethoscopes in limiting contamination risk. A clinician can listen remotely, outside the hot zone. In fact, an infected patient who is minimally ill could be taught to apply the stethoscope himself or herself, potentially reducing some of the transits through the care area, reducing both risk and consumption of personal protective equipment. The cost of a digital stethoscope Bluetooth setup is approximately $650. However, this equipment also has utility in noninfectious circumstances, such as for hands-off or even out-of-room auscultation of fearful or autistic children. Steven J. White, MD, MS Emergency Medicine Department University of Maryland Shore Regional Health Easton, MD http://dx.doi.org/10.1016/j.annemergmed.2014.11.021
Funding and support: By Annals policy, all authors are required to disclose any and all commercial, financial, and other relationships in any way related to the subject of this article as per ICMJE conflict of interest guidelines (see www.icmje.org). The author has stated that no such relationships exist.
Figure. (counter-clockwise from lower left corner): Digital Stethoscope, 3.5 mm male-male connector, BT transmitter, bone-conduction BT headphones.
236 Annals of Emergency Medicine
1. Centers for Disease Control and Prevention. Guidance on personal protective equipment to be used by healthcare workers during management of patients with Ebola virus disease in US hospitals, including procedures for putting on (donning) and removing (doffing). Available at: http://www.cdc.gov/vhf/ebola/hcp/procedures-for-ppe. html. Accessed November 1, 2014. 2. Emory Healthcare Ebola preparedness protocols. Available at: http:// www.emoryhealthcare.org/ebola-protocol/resources.html. Accessed November 1, 2014. 3. Nebraska Medicine. Using telemedicine technology to treat Ebola patients. Available at: http://blogs.nebraskamed.com/blog/2014/11/ using-telemedicine-technology-help-beat-ebola/. Accessed November 22, 2014. 4. Ebola and infectious diseases. Available at: http://www.thinklabs. com/#!ebola-and-biocontainment/c1t8u. Accessed November 21, 2014.
Volume 65, no. 2 : February 2015
In reply: We thank Dr. Schapira and his colleagues for their letter. In regard to the cobinamide dose, several aspects of the drug allow a lower dose than hydroxocobalamin. In addition to cobinamide binding 2 cyanide molecules, it has a much higher affinity for cyanide than hydroxocobalamin, is more water soluble, and is taken up by cells faster. These and other factors likely contribute to the effective dose of cobinamide that is approximately 20% that of hydroxocobalamin. In addition, we have been successful with intraosseous and intramuscular administration of cobinamide to rescue animals from cyanideinduced apnea (unpublished data). In regard to Figured 3D, we apologize that the lines are indeed mislabeled, ie, the cobinamide data are the dashed line, whereas the hydroxocobalamin data are the solid line. As we state in the “Results,” these differences in plasma cyanide concentrations between the 2 groups were not significant, and we attribute the higher cyanide concentrations in the cobinamide-treated animals to be from higher cobinamide binding to plasma proteins. Although additional doses of either antidote might be needed in a longer experiment, the cyanide concentrations were undetectable at 60 minutes in the cobinamide group, similar to the hydroxocobalamin group. In addition, in preliminary experiments with 4 hours of observation, additional doses of cobinamide were not needed. In our model, as in other animal models, apnea is an early effect of cyanide and is followed by hypotension and then cardiac arrest. This pattern has been reported in humans as well. We agree that evaluation of the adverse neurologic effects of cyanide is important in individuals who survive. To this end, we are currently conducting a survival study in a similar model to evaluate neurologic function in surviving animal and neuropathologic findings on necropsy. Lt Col Vikhyat S. Bebarta, MD, USAF Medical Toxicology San Antonio Military Medical Center San Antonio, TX Volume 65, no. 2 : February 2015
David A. Tanen, MD David Geffen School of Medicine at UCLA Harbor-UCLA Medical Center Torrance, CA Susan Boudreau, RN, BSN Maria Castaneda, BS, MS Department of Emergency Medicine San Antonio Military Medical Center San Antonio, TX Lee A. Zarzabal, MS Medpro Technologies San Antonio, TX Toni Vargas, PA-C Office of the Chief Scientist/59th MDW Wilford Hall Ambulatory Surgical Center San Antonio, TX Gerry R. Boss, MD University of California San Diego, CA http://dx.doi.org/10.1016/j.annemergmed.2014.10.014
Funding and support: By Annals policy, all authors are required to disclose any and all commercial, financial, and other relationships in any way related to the subject of this article as per ICMJE conflict of interest guidelines (see www. icmje.org). The authors have stated that no such relationships exist. The study was funded by the US Air Force Office of the Surgeon General (SG5, FWH20100170A) and the CounterACT Program, Office of the Director, National Institutes of Health and the National Institutes of Neurological Disorders and Stroke, grant U01NS058030. No other funding was used. The views expressed in this article are those of the authors and do not reflect the official policy or position of the Department of the US Air Force, Department of Defense, or the US government.
Auscultation Without Contamination: A Solution for Stethoscope Use With Personal Protective Equipment To the Editor: The Centers for Disease Control and Prevention (CDC) recently released more stringent guidelines1 for how health care providers can best protect themselves from Ebola exposure while putting on and removing personal protective equipment. These guidelines include the routine use of surgical hoods, full face shields, and N-95 respirators or powered air purifying respirators. Hospitals are now Annals of Emergency Medicine 235
Correspondence scrambling to ensure that their providers are properly trained and provisioned. Having participated in mandatory training in donning and doffing personal protective equipment, I think it unlikely that one can safely use a traditional stethoscope in the proposed Ebola care environment, especially if one is a biocontainment novice. Neither the CDC protocol nor the Emory University protocols2 discusses how to safely use a stethoscope without compromising the protective barrier. Thinklabs (Centennial, CO) has developed a digital stethoscope, which processes the sound picked up by the electronic diaphragm into a digital signal and transmits that signal to high-quality earphones or headphones. University of Nebraska providers successfully used this digital stethoscope to evaluate Ebola patients by inserting disposable ear buds before donning face shield and mask or respirator and then snaking the cable out below the impermeable gown.3,4 Subsequent ear bud removal required yanking the cable to displace the ear buds. There are 2 major disadvantages inherent in this approach: first, occlusion of the ear canals compromises communication with the patient and among providers until the ear buds are yanked out, and second, ear bud removal prevents additional auscultation until the next personal protective equipment–donning cycle.
I propose a better solution: the Thinklabs One digital stethoscope connected by its headphone output jack directly to a small Bluetooth transmitter (Avantree, Shenzhen, China) through a male-to-male 3.5-mm connector (Figure). The digital signal can then be transmitted to bone-conduction Bluetooth headphones (Blues2; Aftershokz, East Syracuse, NY). Such headphones transmit sounds to the middle ear by bone conduction and leave the external ear canal unobstructed. I have used such a setup in the emergency department for more than 2 months and find that I have excellent sound quality of heart and lung sounds while still being able to converse with patients and staff. In a proofof-concept test, I was able to perform auscultation remotely from 30 m away. I did have to perform some minor nonbillable surgery on the 3.5-mm connector so that it would fit into the recessed headphone jack of the digital stethoscope; this took about 2 minutes with a #11 size scalpel. A similar setup could provide significant advantages over conventional stethoscopes in limiting contamination risk. A clinician can listen remotely, outside the hot zone. In fact, an infected patient who is minimally ill could be taught to apply the stethoscope himself or herself, potentially reducing some of the transits through the care area, reducing both risk and consumption of personal protective equipment. The cost of a digital stethoscope Bluetooth setup is approximately $650. However, this equipment also has utility in noninfectious circumstances, such as for hands-off or even out-of-room auscultation of fearful or autistic children. Steven J. White, MD, MS Emergency Medicine Department University of Maryland Shore Regional Health Easton, MD http://dx.doi.org/10.1016/j.annemergmed.2014.11.021
Funding and support: By Annals policy, all authors are required to disclose any and all commercial, financial, and other relationships in any way related to the subject of this article as per ICMJE conflict of interest guidelines (see www.icmje.org). The author has stated that no such relationships exist.
Figure. (counter-clockwise from lower left corner): Digital Stethoscope, 3.5 mm male-male connector, BT transmitter, bone-conduction BT headphones.
236 Annals of Emergency Medicine
1. Centers for Disease Control and Prevention. Guidance on personal protective equipment to be used by healthcare workers during management of patients with Ebola virus disease in US hospitals, including procedures for putting on (donning) and removing (doffing). Available at: http://www.cdc.gov/vhf/ebola/hcp/procedures-for-ppe. html. Accessed November 1, 2014. 2. Emory Healthcare Ebola preparedness protocols. Available at: http:// www.emoryhealthcare.org/ebola-protocol/resources.html. Accessed November 1, 2014. 3. Nebraska Medicine. Using telemedicine technology to treat Ebola patients. Available at: http://blogs.nebraskamed.com/blog/2014/11/ using-telemedicine-technology-help-beat-ebola/. Accessed November 22, 2014. 4. Ebola and infectious diseases. Available at: http://www.thinklabs. com/#!ebola-and-biocontainment/c1t8u. Accessed November 21, 2014.
Volume 65, no. 2 : February 2015
