Marine Mammal Lung Dynamics when Exposed to Underwater Explosion Impulse

Abstract

Very little is known about marine mammal susceptibility to primary blast injury (PBI) except in rare cases of opportunistic studies. As a result, traditional analysis techniques relied on methods developed more than 30 years ago using terrestrial mammals as surrogates. Modeling tools available today have the computing power to vastly improve calculation of safe ranges and injury zones from underwater explosions (UNDEX) employing morphologically accurate proxies with material properties similar to marine mammal tissues. The Dynamic System Mechanics Advanced Simulation (DYSMAS) fluid–structure interaction (FSI) software is being used to simulate the complex phenomena of UNDEX, shock wave, and bubble pulse propagation through the water and transmission of energy to a cetacean focusing on the dynamic response of the thoracic cavity and air‐filled lungs to a shock wave. The approach integrates fluid and structural analyses with the material properties of blubber, bone, and muscle using marine mammal morphometrics to eliminate unnecessary assumptions made during more traditional approaches to analysis developed before these types of data and computational power were available. DYSMAS analyses of a 1D gas bubble surrounded by water was found to closely match the classical bubble dynamics models. Further, DYSMAS models of a spherical gas bubble surrounded by tissue and rib structure demonstrate a global radial oscillation of the gas bubble, but also show significant local deflection and material strain in response to the UNDEX loading. The intended result of the investigation is an improved and scientifically defensible understanding of the effects of UNDEX on marine mammals. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc. Anat Rec, 302:718–734, 2019. Published 2018. This article is a U.S. Government work and is in the public domain in the USA.

The dynamic response of human lungs due to underwater shock wave exposure

“…To gain insights into this interesting PV behavior, we solved a RP equation where a spherical gas bubble within a domain of incompressible liquid subject to a short-duration pressure square wave [ 30 , 31 ]. Fetherston et al solved a similar equation to understand the dynamics of marine mammal lungs when exposed to underwater blast [ 36 ]. Although this RP model oversimplifies the complexities of lung composition, material properties, and structure, the PV time series ( Fig 5A ) exhibits waveform morphologies that are remarkably similar to those of the lung (Figs 2A and 4B ).…”

“…Due to the liquid incompressibility, R S is related to R via volume conservation by where and R 0 are the initial shell radius and bubble radius, respectively. While other versions of the RP equation [ 35 , 36 ] that can better generalize to other boundary conditions, this version of the confined RP was chosen due to the inclusion of key parameters without undue complexity. Other models of the lungs that account for structure, material properties, and geometry [ 36 – 39 ] were considered, but complexity beyond the needs of this study placed these models out of scope.…”

From specialized skin to sensing whiskers to unique depth perception mechanisms to novel eyes and much, much more: The distinctive ways marine mammals interact with their world are explored in a Special Issue of the The Anatomical Record

“…This extraordinary conference resulted in a Thematic Papers Issue entitled “Mysticete anatomy and evolution,” Guest Edited by our ever‐energetic Joy Reidenberg (Laitman & Albertine, 2019; Reidenberg, 2019). Notable among some of the insights in this issue were observations on features of how marine mammal lungs respond to underwater blast dynamics (Fetherston et al, 2019); detailed comparative study of the semiaquatic moose nasal complex and how this sheds light on the evolution of ancestral cetaceans (Marquez et al, 2019); and a comparison of the nostrils in the hippopotamus and mysticetes as a means to understand both their function and evolutionary relationships (Maust‐Mohl et al, 2019). (This meeting was very successful in decanting JL's cold rooms and freezers of considerable material; you‐know‐who has already restocked them!…”

Mysticetes to MiniConference to Manuscripts: Introduction to Thematic Issue on Mysticete Anatomy

“…The respiratory anatomy theme is continued with a manuscript on: Investigation of Marine Mammal Lung Dynamics when Exposed to Underwater Explosion Impulse (Fetherston et al, 2018). This paper is different from our usual anatomically focused articles in that it delves into modeling marine mammal lungs undergoing conformational changes when subjected to an underwater explosion.…”