In reply:

Abstract

The comments we received in response to the supplement chapter “Blast Physics and Pathophysiology”1Westrol M.S. Donovan C.M. Kapitanyan R. Blast physics and pathophysiology of explosive injuries.Ann Emerg Med. 2017; 69: S4-S9Abstract Full Text Full Text PDF PubMed Scopus (17) Google Scholar are much appreciated. We also appreciate and recognize the commenter’s significant contributions to the subject matter. In fact, the section describing shear waves and stress waves was synthesized from the review article by Wightman and Gladish,2Wightman J.M. Gladish S.L. Explosions and blast injuries.Ann Emerg Med. 2001; 37: 664-678Abstract Full Text Full Text PDF PubMed Scopus (291) Google Scholar as well as the work from other military physicians.3Ritenour A.E. Baskin T.W. Primary blast injury: update on diagnosis and treatment.Crit Care Med. 2008; 36: S311-S317Crossref PubMed Google Scholar Our intent was to describe the supersonic speed of the primary blast wave rather than the speed of tissue movement within the body. On interaction with the body and tissue interfaces, the wave undergoes deceleration, imparting various forces on the tissues and organs. The complex interaction of forces results in the injuries observed from primary blast injury. The effect of stress and shear waves on tissues, as well as the idea of spallation, as a form of damage is maintained across several sources. Readers are directed to the article’s sources for further information on the effect of blast wave overpressure on tissues. We agree that the primary pathophysiology of blast lung is from extrinsic compression of the thorax. The statement in regard to intrathoracic pressure and “mechanical chest compressions”1Westrol M.S. Donovan C.M. Kapitanyan R. Blast physics and pathophysiology of explosive injuries.Ann Emerg Med. 2017; 69: S4-S9Abstract Full Text Full Text PDF PubMed Scopus (17) Google Scholar was not an implication that blast waves compress the chest like cardiopulmonary resuscitation in an anterior-posterior manner. Rather, we intended to make an analogy to a more familiar cause of intrathoracic pressurization from extrinsic forces. Figure 2 portrays a pressurization of the tracheobronchial tree. According to the animal studies cited above,4Benzinger T. Physiological effects of blast in air and water.in: German Aviation Medicine. World War II, Vol. 2. Office of the Surgeon General of the United States Air Force, Washington, DC1950: 1225-1259Google Scholar tracheobronchial pressurization does not appear to be the primary cause of pulmonary injury. The pressurization of the upper airways does appear to cause injury, as well as prevent the exit of airway pressures from the lungs during thorax blast compression. Subglottic airway injuries do seem to occur. Eckert et al5Eckert M.J. Clagett C. Martin M. et al.Bronchoscopy in the blast injury patient.Arch Surg. 2006; 141: 806-811Crossref PubMed Scopus (18) Google Scholar described bronchoscopic findings of a case series of 24 blast-injured patients. Sixteen of 23 patients (70%) had airway erythema and edema, causing a narrowing of greater than 50% airway patency within 6 to 12 hours of initial injury. Animal studies on the pathophysiology of blast lung are limited, including nonpeer-reviewed experiments. It is possible that the increased resistance of the smaller airways of small animals such as rabbits and rats prevents tracheobronchial transmission of pressurization. A recent case report suggests that airway pressurization in humans is an understudied mechanism of injury in blasts.6McLaughlin S. Bouhaidar R. Post-mortem CT appearances in pulmonary blast injury secondary to shotgun suicide.J Forensic Radiol Imaging. 2015; 3: 131-133Abstract Full Text Full Text PDF Scopus (3) Google Scholar We can all agree that further research into the pathophysiology of blast lung injury is needed. Blast Physics and Pathophysiology of Explosive InjuriesAnnals of Emergency MedicineVol. 69Issue 1PreviewThe medical professional’s approach to a blast incident and the resulting patients is a difficult one. Explosions, whether accidental or intentional, wreak physical and psychological havoc on the patients, as well as the medical professionals involved with incident response and caring for the victims. It is further complicated by the fact that most first responders and physicians have little to no experience handling the aftereffects of an explosion, which only adds anxiety to the situation. Data in the United States have indicated approximately 200 injuries or fatalities per year from bombing incidents; with approximately 40,000 physicians practicing emergency medicine and severalfold more emergency responders, one could go his or her entire career without encountering a blast injury. Full-Text PDF Pathophysiology of Primary Blast InjuryAnnals of Emergency MedicineVol. 70Issue 1PreviewI read with great interest the recent Annals supplement titled “Best Practices for Management of Explosive Incidents.” I commend Telemedicine and Advanced Technology Research Center for funding and Robert Wood Johnson University Hospital for accomplishing this project. Full-Text PDF