Note 2 - Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues	$ 24,865	$ 22,954	$ 50,007	$ 45,627
Consumables [Member] \| Transferred at Point in Time [Member]
Revenues	11,394	10,438	23,560	20,969
Hardware [Member] \| Transferred at Point in Time [Member]
Revenues	7,569	6,723	14,653	13,568
Service [Member] \| Transferred at Point in Time [Member]
Revenues	3,476	3,236	6,869	6,373
Service [Member] \| Transferred over Time [Member]
Revenues	2,426	2,557	4,925	4,717
Sterilzation and Disinfection Control [Member]
Revenues	11,582	9,985	22,930	20,168
Sterilzation and Disinfection Control [Member] \| Consumables [Member] \| Transferred at Point in Time [Member]
Revenues	9,093	8,206	18,663	16,875
Sterilzation and Disinfection Control [Member] \| Hardware [Member] \| Transferred at Point in Time [Member]
Revenues	704	221	908	354
Sterilzation and Disinfection Control [Member] \| Service [Member] \| Transferred at Point in Time [Member]
Revenues	291	312	642	521
Sterilzation and Disinfection Control [Member] \| Service [Member] \| Transferred over Time [Member]
Revenues	1,494	1,246	2,717	2,418
Instruments [Member]
Revenues	8,704	7,983	17,435	16,586
Instruments [Member] \| Consumables [Member] \| Transferred at Point in Time [Member]
Revenues	641	553	1,433	1,497
Instruments [Member] \| Hardware [Member] \| Transferred at Point in Time [Member]
Revenues	5,672	5,230	11,212	10,770
Instruments [Member] \| Service [Member] \| Transferred at Point in Time [Member]
Revenues	2,391	2,200	4,790	4,319
Instruments [Member] \| Service [Member] \| Transferred over Time [Member]
Revenues
Cold Chain Monitoring [Member]
Revenues	2,950	3,151	6,173	6,068
Cold Chain Monitoring [Member] \| Consumables [Member] \| Transferred at Point in Time [Member]
Revenues	127	80	191	111
Cold Chain Monitoring [Member] \| Hardware [Member] \| Transferred at Point in Time [Member]
Revenues	1,193	1,272	2,533	2,444
Cold Chain Monitoring [Member] \| Service [Member] \| Transferred at Point in Time [Member]
Revenues	698	488	1,241	1,214
Cold Chain Monitoring [Member] \| Service [Member] \| Transferred over Time [Member]
Revenues	932	1,311	2,208	2,299
Cold Chain Packaging [Member]
Revenues	1,629	1,835	3,469	2,805
Cold Chain Packaging [Member] \| Consumables [Member] \| Transferred at Point in Time [Member]
Revenues	1,533	1,599	3,273	2,486
Cold Chain Packaging [Member] \| Hardware [Member] \| Transferred at Point in Time [Member]
Revenues
Cold Chain Packaging [Member] \| Service [Member] \| Transferred at Point in Time [Member]
Revenues	96	236	196	319
Cold Chain Packaging [Member] \| Service [Member] \| Transferred over Time [Member]
Revenues