Objective To investigate the physiological effects of different oxygen injection site on ventilatory status and oxygenation during noninvasive positive pressure ventilation ( NPPV) with portable noninvasive ventilators. Methods A prospective crossover randomized study was performed. Oxygen injection site was randomized into the outlet of the ventilator, the connection site between mask and circuit, and the mask under the condition of leak port immobilized in the mask. Oxygen flow was retained in the baseline level at the initial 5 to 10 minutes, and adjusted to obtain arterial oxygen saturation measured by pulse oximetry ( SpO2 ) ranging from 90% to 95% after SpO2 remains stable. SpO2 at the initial 5 to 10 minutes, oxygen flow, ventilatory status, oxygenation, hemodynamics and dyspnea indexes at0. 5 hour, 1 hour, and 2 hours of NPPV were compared between different oxygen injection sites. Results 10 patients were recruited into the study. Under the condition of the same oxygen flow, SpO2 with oxygen injection site in the outlet of the ventilator was significantly higher than that with oxygen injection site in the connection site between mask and circuit [ ( 98.9 ±0.9) % vs. ( 96.9 ±1.1) % , P =0. 003] , whereas SpO2 with oxygen injection site in the connection site between mask and circuit was significantly higher than that with oxygen injection site in the mask [ ( 96.9 ±1.1) % vs. ( 94.1 ±1.6) %, P = 0.000] . Oxygen flow with oxygen injection site in the mask was statistically higher than that with oxygen injection site at other sites ( P lt; 0.05) . Arterial oxygen tension/ oxygen flow with oxygen injection site in the outlet of the ventilator was significantly higher than that with oxygen injection site in the connection site between mask and circuit ( 67.9 ±31.1 vs. 37.0 ±15.0, P =0.007) , and than that with oxygen injection site in the mask ( 67.9 ± 31.1 vs. 25.0 ±9.1, P = 0.000) . pH, arterial carbon dioxide tension, hemodynamics and dyspnea indexes were not significantly different between different oxygen injection sites ( P gt; 0.05) .Conclusions When portable noninvasive ventilator was applied during NPPV, oxygen injection site significantly affects improvement of oxygenation, and shows a trend for affecting ventilatory status and work of breathing. When the leak port was immobilized in the mask, the nearer oxygen injection site approaches the outlet of the ventilator, the more easily oxygenation is improved and the lower oxygen flow is demanded.
Objective To review the research progress of injection sites of local infiltration analgesia (LIA) in total knee arthroplasty (TKA). MethodsThe relevant domestic and foreign literature in recent years was extensively reviewed. The neuroanatomy of the knee, and the research progress of the selection and the difference of effectiveness between different injection sites of LIA in clinical studies were summarized. ResultsLarge concentrations of nociceptors are present throughout the various tissues of the knee joint. Patellar tendon, subpatellar fat pad, lateral collateral ligament insertions, iliotibial band insertions, suprapatellar capsule, and posterior capsule were more sensitive to pain. Most current studies support injections into the lateral capsule, collateral ligament, retinaculum, quadriceps tendon, fat pad, and subcutaneous tissue. Whether to inject into the back of the knee and subperiosteum is controversial. ConclusionThe relative difference of knee tissue sensitivity to pain has guiding significance for the selection of LIA injection site after TKA. Although researchers have conducted clinical trials on injection site and technique of LIA in TKA, there are certain limitations. The optimal scheme has not been determined yet, and further studies are needed.