| APRV | airway pressure release ventilation |
|---|---|
| APTI | airway pressure time index |
| AR | absolute risk; accounts receivable; achievement ratio; actinic reticuloid [syndrome]; active resista... |
| ARI | acute respiratory illness; airway reactivity index; anxiety reaction, intense |
| ASM | acid sphingomyelinase; airway smooth muscle; American Society for Microbiology; anterior scalenus mu... |