| CPC A61F 2/966 (2013.01) [A61B 17/00234 (2013.01); A61B 17/3421 (2013.01); A61B 17/3468 (2013.01); A61M 25/0013 (2013.01); A61M 25/0054 (2013.01); A61M 25/0138 (2013.01); A61B 2017/00309 (2013.01); A61B 2017/00336 (2013.01); A61F 2/95 (2013.01); A61F 2250/0018 (2013.01)] | 20 Claims | 

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               1. A medical cannula, comprising: 
            an elongate tubular member having a lengthwise axis and a circumferential wall extending between a proximal end and a distal end and defining an interior lumen, the circumferential wall having an outer circumferential surface defining a pattern of openings comprising a plurality of openings arranged in an interrupted spiral that extends circumferentially along the elongate tubular member, each opening of the plurality of openings having a first end that is curved, a first portion of the circumferential wall disposed between immediately adjacent openings within a first revolution of the interrupted spiral, a second portion of the circumferential wall disposed between immediately adjacent openings within a second revolution of the interrupted spiral, the first portion having a first circumferential length along the elongate tubular member, the second portion having a second circumferential length along the elongate tubular member that is different than the first circumferential length; and 
                an outer member disposed circumferentially about the elongate tubular member; wherein a third portion of the circumferential wall is disposed between a first pair of immediately adjacent revolutions of the interrupted spiral, the third portion having a first axial length along the lengthwise axis of the elongate tubular member; and wherein a fourth portion of the circumferential wall is disposed between a second pair of immediately adjacent revolutions of the interrupted spiral, the fourth portion having a second axial length along the lengthwise axis of the elongate tubular member that is different than the first axial length. 
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