Sinus irrigations before and after surgery-Visualization through computational fluid dynamics simulations

Abstract

Objectives/hypothesis: Topical sinus irrigations play a critical role in the management of sinonasal disease, and the improvement in irrigant penetration into the sinuses postoperatively greatly contributes to the success of endoscopic sinus surgery. Prior investigations on postoperative sinus irrigations have been mostly limited to cadaver studies, which are labor intensive and do not capture the full dynamics of the flows. A pilot study was conducted to investigate the impact of surgery on sinus irrigation through computational fluid dynamics (CFD) simulations.

Study design: Retrospective computational study.

Methods: Pre- and postoperative computed tomography (CT) scans were obtained on a patient who underwent standard endoscopic surgeries for all sinuses, including a Draf III frontal sinusotomy. CT-based pre- and postoperative CFD models then simulated irrigations of 120 mL saline per nostril at 12 mL/s (typical of Sinugator) and 60 mL/s (SinusRinse Bottle), in two head positions: face parallel and at a 45° angle to the ground.

Results: Overall, surgery most significantly improved frontal sinus irrigation, but surprisingly resulted in less maxillary and ethmoid sinuses penetration. This may due to the partial removal of the septum during the Draf III, causing most fluid to exit prematurely across the resected septum. Higher flow rate slightly improved ethmoid sinus irrigation, but resulted in less preoperative contralateral maxillary sinus penetration.

Conclusions: CFD modeling of sinonasal irrigations is a novel technique for evaluating irrigant penetration of individual sinus cavities. It may prove useful in determining the optimal degree of surgery or the ideal irrigation strategy to allow for maximal and targeted sinus irrigant penetration.

Level of evidence: NA Laryngoscope, 126:E90-E96, 2016.

Keywords: Nasal irrigation; computational fluid dynamics; frontal; head position; maxillary; modeling; sinus surgery; sinusitis; sphenoid.

Figure 1

Pre and postoperative CT scans of the patient. The interface between the nasal mucosa and the air was delineated using AMIRA® (shown in red) so that sinonasal cavity models can be computationally created subsequently. Preoperatively, frontal sinuses were completely blocked off from the main nasal airway (red indicating air space connected to the outside). The removal of superior septum during the Draf III may cause irrigation fluid to cross pre-maturely across the superior septum (green arrow).

Figure 2

CFD simulated nasal irrigation into the left nostril, at 90° head bent position at12 mL/s flow rates both pre- (top row) and postoperatively (bottom row), snapshots at the end of irrigation (t=10s). Color code is saline fluid velocity (0–2 m/s), which apply to all subsequent figures. Frontal sinuses were not penetrated preoperatively, but fully irrigated postoperatively. The ipsilateral maxillary and ethmoid sinuses were well-irrigated preoperatively. After the Draf III, the removal of superior septum may cause irrigation fluid to spill pre-maturely across the superior septum, and therefore decrease maxillary and ethmoid sinuses penetration.

Figure 3

CFD simulated nasal irrigation into the left nostril, at 90° head position at 60 mL/s flow rates both pre- (top row) and postoperatively (bottom row), snapshots at the end of irrigation (t=2s).

Figure 4

Snapshots at t=0.03, 0.3, 1, 2.5, 3.5, 5s of CFD simulated preoperative nasal irrigation to the left nostril, at 90° head position at 12 mL/s flow rates. End of irrigation snapshot (t=10s) can be found in Figure 2 (top row). Irrigation fluid would first rise up in the ipsilateral side (t=0.03–1s), irrigate the maxillary and ethmoid sinus (t=2.5–5s), and then overflow and spill over the posterior end of the septum to irrigate the contralateral side (t=2.5–5s), before draining out of the contralateral nostril.

Figure 5

CFD simulated nasal irrigation into the left nostril, at 45° head position at 12 mL/s flow rates both pre- (top row) and postoperatively (bottom row), snapshots at the end of irrigation (t=10s).

Figure 6

CFD simulated preoperatively nasal irrigation into the right nostril, at 90° head position at 12 mL/s (top row) and 60 mL/s (bottom row) flow rates, snapshots at the end of irrigation.