Background and Goal of Study: Desaturation (Desat) is common in patients receiving deep sedation or TIVA while on nasal cannula (NC) O2. Increasing O2 flow to improve oxygenation also increases O2 level under the drape close to surgical site and risk of fire hazard. A plastic sheet has been shown to convert NC to a face tent and improves oxygenation in deeply sedated patients during upper GI endoscopy without increasing O2 flow.1–2 Our goal was to confirm its effectiveness in improving oxygenation during MAC/TIVA cases while assessing O2 level under the drape.
Materials and Methods: This retrospective review of patients undergoing various procedures in supine or lithotomy position identified 2 groups. Group 1 received NC O2 (NC, n=44). Group 2 received NC O2 plus a face tent (FT, n=68) using a plastic specimen bag covering the nose and mouth.1–2 Standard monitors were used. Patients received NC O2 (3–10 l/min) and only iv propofol. Data collected included age, weight, height, O2 saturation (Sat), need for assisted ventilation, amount of propofol, the duration, FiO2 and ETCO2. Student's t-test and Chi Square test were used for analysis. A p value < 0.05 was considered as significant. (Mean±S.D)
Results and Discussion: There were no differences in age (NC:52±16 yrs; FT:54±18), ASA status (NC:2.0±0.8; FT:2.1±0.8), room air O2 Sat (98±2%), O2 Sat 5 min after O2, the duration (NC:42±28 min; FT:46±27), ETCO2 and average propofol doseage (NC:149±8 ug/kg/min; FT: 170±8). There were differences in BMI (NC:26±5; FT:29±7), the highest O2 flow (NC:5.5±2.0 l/min; FT:4.5±1.1), FiO2, O2 level under the drape and the lowest O2 Sat, severe Desat (O2 Sat <85%) and need for assisted ventilation. Six NC patients experienced severe Desat (84±11%) and their O2 Sat improved after adding this face tent (5-min intervals: 93±4%, 95±3%, 98±2% and 100±1%).
Conclusion(s): Our data show that this simple technique improves oxygenation and prevents severe desaturation in patients undergoing various MAC/TIVA cases. It may reduce the risk of fire hazard by decreasing O2 level under the surgical drape.