Objective—To assess the in vitro performance of suction drains.
Sample Population—11 drainage systems (3 rigid drains and 8 compressible drains [2 grenade type, 5 concertina type, and 1 pancake type]).
Procedures—A pressure transducer was connected to the patient end of each drainage system. Serial pressure measurements were obtained during incremental addition and removal of air into the reservoir of each system, followed by incremental addition of water. The volume of air removed to restore the initial suction was recorded. Maximum filling volume was compared with the stated reservoir volume. For compressible drains, the suction generated following 3 compression methods was compared.
Results—The initial suction generated by the drainage systems ranged from −633.4 ± 14.7 mm Hg to −90.1 ± 19.5 mm Hg. Rigid drains had greater initial suction than compressible drains. For all compressible drains, compression with 2 hands, rather than 1, produced greater suction, apart from the pancake-type (200-mL reservoir) drains for which the reverse occurred. For grenade-type drains, rolling the reservoir from apex to base generated greater suction than 1-hand compression. Maximum filling volume was lower than stated for the concertina-type drains with 50-mL, 25-mL, and 400-mL reservoirs and the rigid-type drain with a 200-mL reservoir. As increments of air or water were added, compressible drains lost suction rapidly up to a fill of 20% to 30% and then more gradually. Rigid drains lost suction more slowly.
Conclusions and Clinical Relevance—Drainage systems varied widely in their initial suction and rate of loss of suction during filling.
Objective—To evaluate effects of the arytenoid lateralization technique and suture tension on airway pressure in the canine larynx.
Sample—7 canine cadaver larynges.
Procedures—Negative pressure was elicited aboral to the larynx. Airway pressure was measured at airflows of 15 to 120 L/min before and after thyroarytenoid lateralization (TAL), cricoarytenoid lateralization (CAL), and combined TAL and CAL (cricothyroarytenoid lateralization [CTAL]) at 100 and 500 g of suture tension and with sectioning of the sesamoid cartilage (SSC) and disarticulation of the cricothyroid joint (DCTJ). Rima glottidis area (RGA) was measured. Effects of technique, modification, and suture tension on pressure and RGA were evaluated statistically.
Results—Increased suture tension significantly reduced airway pressure for TAL at 30 L/min, CAL at 45 to 120 L/min, and CAL after SSC and DCTJ at 60, 75, and 105 to 120 L/min. The CAL and CTAL caused significantly lower airway pressures than did TAL > 30 L/min, but SSC and DCTJ did not significantly reduce pressure. All procedures, except TAL at 100 g of tension, resulted in a significant RGA increase from baseline. The CAL and CTAL caused a significantly greater RGA than did TAL. For TAL at 100 g of tension, SSC significantly increased RGA.
Conclusions and Clinical Relevance—CAL and CTAL caused lower airway pressures than did TAL. No significant pressure differences were detected between CAL and CTAL; SSC and DCTJ had little effect on pressure. Pressure may be a more sensitive indicator of airflow than is RGA in the larynx of canine cadavers.