Protective potential of different mouthguard thicknesses against perianaesthetic dental trauma: a patient specific-finite element study.

Perianaesthetic dental trauma is a common anaesthesia-related complication. Theprevious studies have shown a lack of knowledge regarding mouthguard usage and controversial results related to perianaesthetic dental trauma prevention. This study aimed to conduct a finite element analysis of the compressive and tensile stresses on the tooth-periodontal ligament-bone complex using custom-made mouthguards of different thicknesses and glass fibre splints to prevent perianaesthetic dental trauma. Custom-fitted ethylene-vinyl acetate mouthguards of two different thicknesses (2 and 3 mm) and glass fibre splint were modelled. A linear static finite element analysis was performed by applying a rigid Macintosh laryngoscope to the palatal surface of the maxillary central incisors at 150 N. The model without a mouthguard and glass fibre splint showed the highest stress values at the palatinal root surfaces during the impact. Increasing the mouthguard thickness significantly decreased the stress-strain values regardless of the presence of the glass fibre splint. Maximum stresses in the group using the 3 mm mouthguard were the lowest compared with the other groups.

Minimal and normal-flow general anesthesia in patients undergoing surgery in prone position: impact on hemodynamics and regional cerebral oxygenation.

PURPOSE: In this study, the aim to assess the combined effects of prone-positioning (PP) and minimal-flow (MF) general anesthesia on regional cerebral oxygenation (RCO) and systemic hemodynamics. METHODS: This is a randomized prospective study aiming to evaluate changes in cerebral oxygenation and hemodynamic parameters in MF systemic anesthesia in patients undergoing surgery in PP. Patients were randomized to MF or normal-flow (NF) anesthesia. In the operating room, pulse rate, mean arterial pressure (MAP), peripheral hemoglobin oxygen saturation (spO2), and right- and left-side RCO (assessed by near-infrared spectroscopy, NIRS) were measured perioperatively. RESULTS: Overall, 46 patients were included (24 in the MF group and 22 in the NF group). The amount of anesthetic gas consumption was significantly lower in the low-flow (LF) group. In both groups, the mean pulse rate showed a decrease after PP. Before induction, RCO was significantly higher both at the right- and left-sides in the LF group compared to the NF group. This difference continued throughout the operation on the left-side and disappeared 10 min after intubation on the right-side. On the left side, mean RCO decreased after PP in both groups. CONCLUSIONS: MF anesthesia in PP did not reduce cerebral oxygenation compared to NF and was safe in terms of systemic hemodynamics and cerebral oxygenation.

Minimal and normal-flow general anesthesia in patients undergoing surgery in prone position: impact on hemodynamics and regional cerebral oxygenation

Purpose: In this study, the aim to assess the combined effects of prone-positioning (PP) and minimal-flow (MF) general anesthesia on regional cerebral oxygenation (RCO) and systemic hemodynamics. Methods: This is a randomized prospective study aiming to evaluate changes in cerebral oxygenation and hemodynamic parameters in MF systemic anesthesia in patients undergoing surgery in PP. Patients were randomized to MF or normal-flow (NF) anesthesia. In the operating room, pulse rate, mean arterial pressure (MAP), peripheral hemoglobin oxygen saturation (spO2), and right- and left-side RCO (assessed by nearinfrared spectroscopy, NIRS) were measured perioperatively. Results: Overall, 46 patients were included (24 in the MF group and 22 in the NF group). The amount of anesthetic gas consumption was significantly lower in the low-flow (LF) group. In both groups, the mean pulse rate showed a decrease after PP. Before induction, RCO was significantly higher both at the right- and left-sides in the LF group compared to the NF group. This difference continued throughout the operation on the left-side and disappeared 10 min after intubation on the right-side. On the left side, mean RCO decreased after PP in both groups. Conclusion: MF anesthesia in PP did not reduce cerebral oxygenation compared to NF and was safe in terms of systemic hemodynamics and cerebral oxygenation.