Comparison of the Effectiveness of Nasal Cannula Versus Face Mask With Reservoir Bag in Postoperative Patients Undergoing General Anesthesia: A Prospective Randomized Controlled Trial.

BACKGROUND: High-concentration oxygen delivery via a face mask (FM) with a reservoir bag is a common practice to prevent postoperative hypoxemia; however, it may also lead to atelectasis and other respiratory complications. Lower concentrations delivered via nasal cannula (NC) may be equally effective in preventing postoperative hypoxemia. The present study aimed to compare peripheral oxygen saturation (SpO_2) delivered via NC versus FM with a reservoir bag in patients who have undergone general anesthesia (GA). METHODS: Eighty-four patients scheduled for GA were randomized to receive either oxygen via NC (NC group, n = 42) or FM with a reservoir bag (FM group, n = 42) for 30 minutes after GA at a postanesthesia care unit (PACU). All patients were assessed based on SpO_2 value, adverse events, and patient satisfaction (measured using a 100-mm visual analog scale). RESULTS: The overall difference between groups in the change of SpO_2 over 30 minutes at the PACU was -0.004 (95% confidence interval, -0.015 to 0.008; P = 0.527). SpO_2 during the first five minutes was lower in NC group, but the difference was not statistically significant. No desaturation occurred in either group, and there was no observed difference between groups in terms of adverse events. Patient satisfaction scores were also similar (P = 0.612). CONCLUSIONS: Oxygen supplementation via NC and via FM with a reservoir bag were equally effective in preventing postoperative hypoxemia after GA.

A randomized double-blind controlled study comparing erector spinae plane block and thoracic paravertebral block for postoperative analgesia after breast surgery.

BACKGROUND: Thoracic paravertebral block (PVB) is an effective regional block for pain control after breast surgery. However, accidentally puncturing adjacent vital structures may cause undesirable complications. Erector spinae plane block (ESPB) has been considered a safer proxy of PVB for beginners. This study aimed to evaluate the analgesic effects of ultrasound-guidance PVB and ESPB after breast surgery. METHODS: This randomized control trial was conducted in patients who underwent mastectomy. Forty-four females were randomly allocated into PVB group or ESPB group. All patients received a block with 20 ml of 0.5% levobupivacaine before general anesthesia. The primary outcome was the 24-h postoperative morphine requirements. The other outcomes of interest were postoperative pain scores, time to first analgesic request, dermatome of sensory blockade, block-related complications, and opioid adverse events. RESULTS: The 24-h morphine requirements were significantly lower in PVB compared to the ESPB group (3.5 ± 3.3 vs. 8.6 ± 3.8 mg, P < 0.001). The overall pain scores were also lower in the PVB group (P < 0.001). Only 14 patients in the PVB group requested additional morphine, whereas all patients in the ESPB group requested it (P = 0.004). The dermatome of sensory blockade was wider in the PVB group (7 vs. 4 levels, P = 0.019). No serious complications occurred in either group. CONCLUSIONS: Compared to ESPB, PVB provided lower postoperative opioid requirements, lower pain scores, and wider sensory blockade after mastectomy.

1-1-8 one-step sevoflurane wash-in scheme for low-flow anesthesia: simple, rapid, and predictable induction.

BACKGROUND: Sevoflurane is suitable for low-flow anesthesia (LFA). LFA needs a wash-in phase. The reported sevoflurane wash-in schemes lack simplicity, target coverage, and applicability. We proposed a one-step 1-1-8 wash-in scheme for sevoflurane LFA to be used with both N2O and Air. The objective of our study was to identify time for achieving each level of alveolar concentration of sevoflurane (FAS) from 1 to 3.5% in both contexts. METHODS: We recruited 199 adults requiring general anesthesia with endotracheal intubation and controlled ventilation-102 in group N2O and 97 in group Air. After induction and intubation, a wash-in was started using a fresh gas flow of O2:N2O or O2:Air at 1:1 L·min- 1 plus sevoflurane 8%. The ventilation was controlled to maintain end-tidal CO2 of 30-35 mmHg. RESULTS: The rising patterns of FAS and inspired concentration of sevoflurane (FIS) are similar, running parallel between the groups. The FAS/FIS ratio increased from 0.46 to 0.72 within 260 s in group N2O and from 0.42 to 0.69 within 286 s in group Air. The respective time to achieve an FAS of 1, 1.5, 2, 2.5, 3, and 3.5% was 1, 1.5, 2, 3, 3.5, and 4.5 min in group N2O and 1, 1.5, 2, 3, 4, and 5 min in group Air. The heart rate and blood pressure of both groups significantly increased initially then gradually decreased as FAS increased. CONCLUSIONS: The 1-1-8 wash-in scheme for sevoflurane LFA has many advantages, including simplicity, coverage, swiftness, safety, economy, and that it can be used with both N2O and Air. A respective FAS of 1, 1.5, 2, 2.5, 3, and 3.5% when used with N2O and Air can be expected at 1, 1.5, 2, 3, 3.5, and 4.5 min and 1, 1.5, 2, 3, 4, and 5 min. TRIAL REGISTRATION: This study was retrospectively registered with ClinicalTrials.gov (NCT03510013) on June 8, 2018.

1-1-12 one-step wash-in scheme for desflurane low flow anesthesia: performance without nitrous oxide.

BACKGROUND: We reported a 1-1-12 wash-in scheme for desflurane-nitrous oxide (N2O) low flow anesthesia that is simple, rapid, and predictable. There remain some situations where N2O should be avoided, which limits the generalizability of this wash-in scheme. The objective of our study was to determine the performance of this scheme in contexts where N2O is not used. METHODS: We recruited 106 patients scheduled for elective surgery under general anesthesia. After induction and intubation, wash-in was started with a fresh gas flow of air:O2 1:1 L/min and a vaporizer concentration of desflurane of 12%. Controlled ventilation was then adjusted to maintain PACO2 at 30-35 mmHg. RESULTS: The alveolar concentration of desflurane (FAD) rose rapidly from 0% to 6% in 4 minutes in the same pattern as observed in our previous study in which N2O was used. An FAD of 7% was achieved in 6 minutes. An FAD of 1% to 7% occurred at 0.6, 1, 1.5, 2, 3, 4, and 6 minutes. The rise in heart rate during wash-in was statistically significant, although not clinically so. There was a slight but statistically significant decrease in blood pressure, but this had no clinical significance. CONCLUSION: Performance of the 1-1-12 wash-in scheme is independent of the use of N2O. Respective FADs of 1%, 2%, 3%, 4%, 5%, 6%, and 7% can be expected at 0.6, 1, 1.5, 2, 3, 4, and 6 minutes.

1-1-12 one-step wash-in scheme for desflurane-nitrous oxide low-flow anesthesia: rapid and predictable induction.

BACKGROUND: We propose a 1-1-12 wash-in scheme for desflurane-nitrous oxide (N2O) low-flow anesthesia. The objective of our study was to determine the time to achieve alveolar concentration of desflurane (FAD) at 1, 2, 3, 4, 5, and 6%. METHODS: We enrolled 106 patients scheduled for elective surgery under general anesthesia. After induction and intubation, wash-in was started with a fresh gas flow (FGF) of N2O : O2 1 : 1 L min(-1) and vaporizer concentration of desflurane (FD) of 12%. Ventilation was controlled to maintain PACO2 at 30-35 mmHg. RESULTS: The FAD rose rapidly from 0 to 4% in 2 min in a linear manner in 0.5 min increments. An FAD of 6% was achieved in 4 min in a linear fashion from FAD of 4% but in 1 min increments. An FAD of 1 to 6% occurred at 0.6, 1, 1.5, 2, 3, and 4 min. Heart rate during wash-in showed a statistically, albeit not clinically, significant pattern of increase. By contrast, blood pressure slightly decreased during this period. CONCLUSIONS: We developed a 1-1-12 wash-in scheme using a FGF of N2O : O2 1 : 1 L min(-1) and FD of 12% for desflurane-nitrous oxide low-flow anesthesia. A respective FAD of 1, 2, 3, 4, 5, and 6% can be expected at 0.6, 1, 1.5, 2, 3, and 4 min.