Influence of Scan Duration on Pulmonary Capillary Hemorrhage Induced by Diagnostic Ultrasound

J of Ultrasound Medicine

Dong

Dou

et al. 2019

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Objectives: Diagnostic ultrasound (DUS) imaging can induce pulmonary capillary hemorrhage (PCH), possibly related to the ultrasonic radiation pressure arising from reflection at the lung blood-air interfaces. Acoustical radiation force impulse (ARFI) elastography is a relatively new diagnostic ultrasound mode with high energy “push-pulses” used to move tissue and generate shear waves. The objective was to characterize DUS-PCH induced by the ARFI elastography mode for comparison to other previously tested DUS modes. Methods: PCH induction was examined for ARFI elastography frames with 5.7 MHz push-pulses (Acuson S3000, Siemens Medical Solutions USA, Mountain View, CA, USA), which had a derated peak rarefactional pressure amplitude (PRPA) of 2.6 MPa. Groups of rats with tracheal tube placement had no ventilation (spontaneous breathing), intermittent positive pressure ventilation (IPPV), or IPPV plus 8 cm H2O of positive end expiratory pressure (PEEP). Exposure was to 1 or 20 manually triggered image frame acquisitions. PCH area was measured on the lung surface. Results: All 20 frame exposure groups, and even the single frame group, had significant PCH relative to shams. One frame exposures produced significantly less PCH (p=0.002) than 20 frame exposure in rats with tracheal tube only (spontaneous breathing). The PEEP inhibited the PCH and produced about half the PCH area induced by IPPV without PEEP (p=0.014). Conclusions: The PCH results were comparable to those from a previous study using B mode or color Doppler mode exposure for 5 min; however, these modes delivered many more pulses for continuous imaging frames, suggesting that the ARFI elastography frames were individually much more effective.

Section: Introductionsupporting

confidence: 63%

Pulmonary Capillary Hemorrhage Induced by Acoustic Radiation Force Impulse Shear Wave Elastography in Ventilated Rats

J of Ultrasound Medicine

Dong

Dou

et al. 2019

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“…Recent results on the induction of PCH from diagnostic US imaging in rats were comparable to early results with laboratory pulsed US, and the US images displayed B‐lines associated with the occurrence and progression of this bioeffect . Animal research has shown that the PCH bioeffect depends on physical parameters, such as the US mode and duration, in addition to the MI. Biological factors also are very important, including sedation, ventilation, age and lung position, and animal species …”

Section: Safety Considerations For Specific Pocus Examinationssupporting

confidence: 53%

“…Unfortunately, the B‐line sign of PCH induction is not useful for safety guidance. The possibility of PCH induction for pulmonary examinations with an MI of greater than 0.4 likely can be excluded when no B‐lines are seen, although very small PCH can escape detection . However, the possibility of US PCH induction for pulmonary examinations with an MI of greater than 0.4 cannot be excluded when B‐lines are seen because of ambiguity in the origin and persistence of the B‐lines.…”

Section: Safety Considerations For Specific Pocus Examinationsmentioning

confidence: 99%

Diagnostic Ultrasound Safety Review for Point‐of‐Care Ultrasound Practitioners

J of Ultrasound Medicine

Abo

Abramowicz

et al. 2019

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Potential ultrasound exposure safety issues are reviewed, with guidance for prudent use of point-of-care ultrasound (POCUS). Safety assurance begins with the training of POCUS practitioners in the generation and interpretation of diagnostically valid and clinically relevant images. Sonographers themselves should minimize patient exposure in accordance with the as-low-as-reasonably-achievable principle, particularly for the safety of the eye, lung, and fetus. This practice entails the reduction of output indices or the exposure duration, consistent with the acquisition of diagnostically definitive images. Informed adoption of POCUS worldwide promises a reduction of ionizing radiation risks, enhanced cost-effectiveness, and prompt diagnoses for optimal patient care.

“…The duty cycle was about the same for both sets of data. Possibly, the most important difference for the threshold difference was the exposure duration difference of 10 s or 180 s. The threshold may also depend on exposure duration for diagnostic ultrasound (Miller et al 2016a). …”

Section: Experimental Backgroundmentioning

confidence: 99%

“…The PCH from P RSa should add to stress present due to various physiological conditions. For example, the anesthetic components xylazine and dexmedetomidine, α 2 adrenergic receptor agonists which effect pulmonary circulation, have a strong enhancing influence on PCH (Miller et al 2015c; Miller et al 2016a). Xylazine is a sedative and analgesic which produces significant cardiovascular and respiratory depression (Flecknel, 2009).…”

Section: Consideration Of Ultrasound Interaction With the Blood-gas Bmentioning

confidence: 99%

Mechanisms for Induction of Pulmonary Capillary Hemorrhage by Diagnostic Ultrasound: Review and Consideration of Acoustical Radiation Surface Pressure

Ultrasound in Medicine & Biology

2016

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Diagnostic ultrasound can induce pulmonary capillary hemorrhage (PCH) in rats and other mammals. This phenomenon represents the only clearly demonstrated biological effect of (non-contrast enhanced) diagnostic ultrasound and thus presents a uniquely important safety issue. However, the physical mechanism responsible for PCH remains uncertain more than 25 y after its discovery. Experimental research has indicated that neither heating nor acoustic cavitation, the predominant mechanisms for bioeffects of ultrasound, is responsible for PCH. Furthermore, proposed theoretical mechanisms based on gas body activation, on alveolar resonance and on impulsive generation of liquid droplets all appear unlikely to be responsible for PCH, owing to unrealistic model assumptions. Here, a simple model based on the acoustic radiation surface pressure (ARSP) at a tissue-air interface is hypothesized as the mechanism for PCH. The ARSP model seems to explain some features of PCH, including the approximate frequency independence of PCH thresholds, and the dependence of thresholds on biological factors. However, ARSP evaluated for experimental threshold conditions appear to be too weak to fully account for stress failure of pulmonary capillaries, gauging by known stresses for injurious physiological conditions. Furthermore, consideration of bulk properties of lung tissue suggests substantial transmission of ultrasound through the pleura, with reduced ARSP and potential involvement of additional mechanisms within the pulmonary interior. Although these recent findings advance our knowledge, only a full understanding of PCH mechanisms will allow development of science-based safety assurance for pulmonary ultrasound.