Ambulatory surgery: room air versus nasal cannula oxygen during transport after general anesthesia

We compared outpatients transported to the postanesthesia care unit (PACU) while breathing room air to 2-4 L/min nasal cannula oxygen (O2) to test the hypothesis that routine supplemental O2 during transport is not required after general anesthesia in an ambulatory surgery center. We also examined whether the arbitrary arrival PACU O2 saturations of > 92% may be used to predict an infrequent incidence of subsequent significant desaturations (< 90%) in the PACU. One-hundred-ninety patients were randomized to receive either room air or 2-4 L/min nasal cannula for transport to PACU after receiving general anesthesia. O2 saturations were recorded before surgery, just before leaving the operating room, and upon arrival in the PACU. The lowest O2 saturation occurring in the PACU was also recorded. The mean arrival PACU O2 saturation was 95.0 in the Room Air group, compared with 97.2 for the Nasal Cannula (NC) group, a statistically significant difference (P < 0.001). In the Room Air group, 20% had arrival O2 saturations < or = 92%, and half of these (10%) had O2 saturations < 90%. In the NC group, 6% had O2 saturations < or = 92%, of which one third (2%) were < 90% on arrival in the PACU. All of these initial desaturations were easily corrected with face-tent O2 administration, deep breathing, or both. Subgroup analysis revealed that patients whose ages were 60 yr or older or those weighing 100 kg or more had lower arrival room air saturations than their younger or slimmer counterparts. In the Room Air group, only three (3.9%) of the patients that arrived in PACU with O2 saturations > 92% had subsequent desaturations < 90%, compared with seven (7.9%) in the NC group. We conclude that most adult patients undergoing ambulatory surgery can be transported safely to the PACU breathing room air after general anesthesia. However, patients whose age was > or = 60 yr or weight was > or = 100 kg, or for whom transient O2 desaturation on transport may be harmful, should be transported while breathing nasal O2 via nasal cannula. IMPLICATIONS: Most adult patients undergoing ambulatory surgery can be transported safely to the PACU breathing room air after general anesthesia. However, patients whose age was > or = 60 yr or weight > or = 100 kg, or for whom transient O2 desaturation on transport may be harmful, should be transported while breathing oxygen via nasal cannula.     

Randomized trial of a novel double lumen nasopharyngeal catheter versus traditional nasal cannula during total intravenous anesthesia for gastrointestinal procedures

Study objectivePatients undergoing general anesthesia routinely experience episodes of hypoxemia. There are multiple causes of procedural oxygen desaturation including upper airway obstruction and central hypoventilation. We hypothesize that oxygen supplementation via nasopharyngeal catheter (NPC) will decrease the number of episodes of hypoxemia as compared to traditional NC oxygen supplementation in patients undergoing general anesthesia provided by an anesthesia provider for gastrointestinal endoscopy procedures.DesignRandomized control trial.SettingEndoscopy suite.PatientsSixty patients undergoing intravenous general anesthesia for endoscopic gastrointestinal procedures that did not require endotracheal intubation were enrolled.InterventionsPatients were randomized to receive supplemental oxygen by either a standard nasal cannula or a nasopharyngeal catheter. Initial oxygen flow rate was 4 l/min and titrated at the anesthesia provider's discretion. Intravenous anesthetic consisted of a propofol infusion.MeasurementsHypoxemia was defined as a pulse oximetry reading of < 92%. Secondary outcomes included number of airway assist maneuvers such as jaw lift or other airway interventions.Main resultsOf the 60 enrolled patients; three subjects in the NPC group were excluded from further analysis. There was no difference between group in age, ASA classification, Body Mass Index, oropharyngeal classification or total propofol dose.Patients who received nasopharyngeal oxygen supplementation were less likely to experience a clinically significant oxygen desaturation event 3 of 27 (11.0%) versus 12 of 30 subjects (40.0%), p = 0.013. Interventions to assists with airway management were required for fewer patients in the NPC group 4 (14.8%) versus the NC group, 17 (56.7%), p = 0.001.ConclusionOxygen supplementation via a nasopharyngeal catheter during intravenous general anesthesia resulted in significantly fewer episodes of hypoxemia and number of airway assist maneuvers. Future studies are needed to assess the utility of NPC in other clinical environments where supplemental oxygen is required in the setting of potential airway obstruction.     

Postanesthesia emergence in patients with post-traumatic stress disorder

Study objectiveRecovery from anesthesia may be complicated with development of severe panic symptoms and anxiety. Preexisting anxiety disorder has been reported as a risk factor for development of these symptoms. We aimed to examine the frequency of emergence delirium (EDL) among veterans diagnosed with posttraumatic stress disorders (PTSDs).DesignRetrospective cohort.SettingPostoperative recovery area.PatientsPerioperative information of 1763 consecutive patients who underwent a surgical procedure requiring general anesthesia were collected. The patients were grouped on the basis of previous diagnosis of PTSD. A total of 317 patients were identified with a positive history of PTSD and were compared to 1446 patients without such a history for the occurrence of EDL in the postanesthesia care unit (PACU) as the primary endpoint.MeasurementsDuration of stay in PACU in minutes and the frequency of hospital admission were the secondary endpoints. Multivariate binary logistic regression analysis was performed to identify the predictors of EDL among the veteran population.Main resultsEmergence delirium was reported in 37 cases (2.1%) after general anesthesia. Fifteen (4.7%) of 317 patients with PTSD and 22 (1.5%) of 1446 patients without history of PTSD demonstrated symptoms related to EDL in the PACU (P = .002). After propensity matching, there were 8 patients with EDL in the PTSD group whereas there were only 2 patients with EDL among controls. Posttraumatic stress disorder was also an independent predictor of EDL in multivariate analysis with an odds ratio of 6.66 and a 95% confidence interval of 2.04 to 21.72 (P = .002).ConclusionsPosttraumatic stress disorder independently predicted the frequency of EDL even after correcting for preexisting depression and anxiety disorders. A relatively longer duration of PACU stay in PTSD patients may reflect raised awareness of the health care workers about this debilitating mental disorder.     

Pulse oximetry reduces the unnecessary administration of oxygen in the postanesthesia recovery period

OBJECTIVES: To investigate whether patients admitted to the postanesthesia recovery unit (PRU) need routine oxygen supplementation in the immediate postoperative period, by measuring changes in arterial oxygen saturation (SpO2) with a pulse oximeter. MATERIAL AND METHODS: Two hundred ninety-nine patients were admitted to the PRU after surgery. All breathed room air after their operations. During transfer to and time in the PRU, SpO2 was recorded. We administered oxygen through a face mask to patients whose SpO2 fell below 94% and to patients whose SpO2 levels fell below baseline, when baseline values were less than 94%. We recorded patient data, physical status (ASA), type of anesthesia, duration of surgery, Aldrete score upon admission to the PRU and SpO2 before and after surgery while the patient breathed room air. RESULTS: General anesthesia was used in 82.3% of the patients and local-regional anesthesia with sedation in 17.7%. PRU stay was 75.6 +/- 92.4 min. Twenty-five percent of the patients were treated with oxygen after surgery and 75% did not require supplemental oxygen. Time until the appearance of desaturation was 3.3 +/- 2.8 min. The coefficient of multiple correlation between postoperative SpO2 while breathing room air (dependent variable) and preoperative SpO2, age and duration of surgery was R = 0.522 (p < 0.001). CONCLUSIONS: Our results are sufficient to demonstrate the validity of pulse oximetry for avoiding indiscriminate oxygen supplementation in patients admitted to the PRU.     

The Need for a Step-up in Postoperative Medical Care is Predictable in Orthopedic Patients Undergoing Elective Surgery

Background

The goal of elective orthopedic surgery is to return patients to their expected level of activity without an increased incidence of postoperative complications. The first step is identifying patient and/or surgical characteristics responsible for these complications.

Questions/Purposes

This study sought to identify predictors of a step-up in medical care after non-ambulatory elective orthopedic surgery.

Methods

At a single specialty orthopedic hospital, we identified all in-hospital postoperative patients who were transferred to a higher level of medical care ((PACU) post-anesthesia care unit). The characteristics of both transferred and non-transferred patients were compared. A model was built which incorporated predictors of return to a higher level of care.

Results

During a 1-year period, 155 of 7967 patients (1.95%) required transfer to the PACU within 5 days of surgery. Cardiac complications were the major reason for transfer (50.3%), followed by pulmonary (11.0%) and neurological complications (9.7%). Patients who returned to the PACU were older, had more Exlihauser comorbidities, and had obstructive sleep apnea (OSA). In a model adjusting for all patient characteristics: age, American Society of Anesthesiologists (ASA) status, congestive heart failure (CHF), the Charlson comorbidity index and OSA predicted return to the PACU.

Conclusions

In an elderly population with multiple comorbidities undergoing elective common major orthopedic procedures, approximately 2% of patients required readmission to the PACU. The most common problems requiring this step-up in care were cardiac and pulmonary, which resulted in an increased length of hospital stay. Patients with OSA and multiple comorbidities undergoing total knee arthroplasty carry an increased risk for postoperative complications.

     

Uncommon cause of respiratory distress in the post-anaesthesia care unit

We report a case of respiratory distress in the post anesthesia care unit following general anaesthesia for a dilatation and curettage related to miscarriage in a 32-year-old woman. The preoperative physical examination showed no abnormalities except for the presence of dry cough during the preceding two or three days. A few minutes after her arrival in the PACU, the patient developed hyperthermia till 40.6 degrees C, cough, polypnea and oxygen desaturation (SpO(2): 82% on FiO(2): 40%). A thoraco-abdominal angioscanner showed pulmonary basal condensations and a thrombosis of the right ovarian vein. The patient had to be transferred to the intensive care unit where she remained intubated and ventilated during 13 days because of a Haemophilus influenzae pneumonia.     

Nursing Workload Associated with Adverse Events in the Postanesthesia Care Unit

Background: The authors used a nursing task inventory system to assess nursing resources for patients with and without adverse postoperative events in the postanesthesia care unit (PACU).

Methods: Over 3 months, 2,031 patients were observed, and each task/activity related to direct patient care was recorded and assigned points according to the Project Research in Nursing (PRN) workload system. PRN values for each patient were merged with data from an anesthesia database containing demographics, anesthesia technique, and postoperative adverse events. Mean and median PRN points were determined by age, sex, duration of procedure, and mode of anesthesia for patients with and without adverse events in the PACU. Three theoretical models were developed to determine the effect of differing rates of adverse events on the requirements for nurses in the PACU.

Results: The median workload (PRN points) per patient was 31.0 (25th-75th percentile, 25-46). Median workload was 26 points for patients with no postoperative events and 155 for >= six adverse events. Workload varied by type of postoperative event (e.g., unanticipated admission to the intensive care unit, median workload = 95; critical respiratory event = 54; and nausea/vomiting = 33). Monitored anesthesia care or general anesthesia with spontaneous ventilation used less resources compared with general anesthesia with mechanical ventilation. Modeling various scenarios (controlling for types of patients) showed that adverse events increased the number of nursing personnel required in the PACU.     

Nocturnal episodic hypoxemia after ambulatory breast cancer surgery: comparison of sevoflurane and propofol-fentanyl anesthesia

Purpose To study the incidence and severity of nocturnal episodic hypoxemia after ambulatory breast cancer surgery and its differences with sevoflurane and propofol anesthesia. Methods Sixty-one adult female patients (ASA PS I–II; age, 32–77 years) without an apparent history of sleep apnea and respiratory disease undergoing major breast cancer surgery on an outpatient basis and with planned overnight admission were randomized to one of two anesthesia maintenance groups: sevoflurane anesthesia (SEV, n = 31) or intravenous propofol, fentanyl, and vecuronium anesthesia (TIVA, n = 30). All patients were administered propofol 2 mg·kg⁻¹ intravenously for anesthesia induction, had a laryngeal mask airway placed, and received rectal diclofenac and local infiltration anesthesia for pain relief. No opioid analgesic or oxygen was administered after discharge from the postanesthesia care unit (PACU). Oxygen saturation (Sp_O2) was recorded continuously during the first postoperative night. Sp_O2 <90% that lasted >10 s was regarded as hypoxemia, and the percentage of effective recording time with Sp_O2 <90% (%time with Sp_O2 <90) was evaluated. Results Six patients (SEV3/TIVA3) had >1% of %time with Sp_O2 <90 (S-hypoxemia group), 17 (SEV7/TIVA10) had >0% and ≤1% (M-Hypoxemia group), and 38 (SEV21/TIVA17) had 0% (no-hypoxemia group). There were no statistical differences in age, ASA PS, anesthesia technique, and duration of anesthesia among groups. The S-hypoxemia group had higher body mass index (BMI) and incidence of oxygen supplementation in the PACU than the no-hypoxemia group. No patient had major complications. Conclusion Nocturnal episodic hypoxemia occurs frequently after ambulatory breast cancer surgery. The incidence was not different between SEV and TIVA. Hypoxic patients had a higher BMI and needed oxygen therapy in PACU more frequently. This work was presented in part at the 6th International Congress of Ambulatory Surgery in Seville, Spain, and at the 52th Congress of the Japanese Society of Anesthesiologists in Kobe, Japan.     

Distal peripheral nerve blockade for patients undergoing hand surgery: a pilot study

BackgroundData are limited regarding the use of peripheral nerve blockade at the level of the forearm, and most studies regard these procedures as rescue techniques for failed or incomplete blocks. The purpose of the study was to investigate patients undergoing hand surgery with distal peripheral nerve (forearm) blocks and compare them with patients having similar procedures under more proximal brachial plexus blockade. No investigations comparing distal nerve blockade to proximal approaches are currently reported in the literature.MethodsMedical records were retrospectively reviewed for patients who had undergone hand surgery with a peripheral nerve block between November 2012 and October 2013. The primary outcome was the ability to provide a primary anesthetic without the need for general anesthesia or local anesthetic supplementation by the surgical team. Secondary outcome measures included narcotic administration during the block and intraoperative procedures, block performance times, and the need for rescue analgesics in the post anesthesia care unit (PACU).ResultsNo statistical difference in conversion rates to general anesthesia was observed between the two groups. Total opiate administration for the block and surgical procedure was lower in the forearm block group. There was no difference in block performance times or need for rescue analgesics in the PACU.ConclusionsForearm blocks are viable alternatives to proximal blockade and are effective as a primary anesthetic technique in patients undergoing hand surgery. Compared to the more proximal approaches, these blocks have the benefits of not causing respiratory compromise, the ability to be performed bilaterally, and may be safer in anticoagulated patients.     

Effect of intraoperative subhypnotic infusion of propofol on postoperative nausea and vomiting: A retrospective analysis

Study objectiveTo measure the possible association between subhypnotic propofol infusion during general balanced anesthesia and the incidence of PONV.DesignRetrospective Cohort Analysis Using Propensity Score Matching.SettingPostanesthesia care unit and inpatient unit.PatientsPatients with American Society of Anesthesiologists (ASA) physical status I-IV, undergoing non-cardiac surgery lasting >2 h were included. Patients were excluded if transferred to the intensive care unit after surgery or received ketamine. Initially 70,976 patients were screened, and a cohort of 51,707 eligible adult patients undergoing non-cardiac surgery under general balanced anesthesia between 2015 and 2019 were included. Using a propensity score matching, 3185 patients who received subhypnotic propofol during general balanced anesthesia were matched with 5826 patients who did not receive subhypnotic propofol in a 1:2 ratio.InterventionsNone.MeasurementsThe primary outcome was the incidence of PONV during PACU stay. The secondary outcome was the incidence of PONV within the first 24 h after surgery. Exploratory outcomes were time-to-extubation and length of hospital stay.Main resultsA total of 9011 patients were included (3185 patients who received propofol infusion, and 5826 patients who did not receive propofol infusion) after propensity score matching. The adjusted odds ratio for PONV incidence was 1.03 (95% CI: 0.90, 1.18; p = 0.635) in PACU, and 1.05 (95% CI: 0.90, 1.23; P = 0.50) within 24 h after surgery. The length of hospital stay was 6 h shorter (ratio of means (95% CI) of 0.92, 0.89, 0.94), p < 0.001) and time-to-extubation was 2 min longer (ratio of means 1.24 (1.20, 1.28), p < 0.001) in patients receiving subhypnotic propofol infusion.ConclusionsOur study suggests that subhypnotic propofol infusion during general balanced anesthesia is not associated with a reduction in the incidence of PONV during PACU stay and within the first 24 h after surgery. However, it is associated with decreased LOS and increased time-to-extubation, but differences in neither outcome were clinically important.     

Nursing workload associated with adverse events in the postanesthesia care unit

BACKGROUND: The authors used a nursing task inventory system to assess nursing resources for patients with and without adverse postoperative events in the postanesthesia care unit (PACU). METHODS: Over 3 months, 2,031 patients were observed, and each task/activity related to direct patient care was recorded and assigned points according to the Project Research in Nursing (PRN) workload system. PRN values for each patient were merged with data from an anesthesia database containing demographics, anesthesia technique, and postoperative adverse events. Mean and median PRN points were determined by age, sex, duration of procedure, and mode of anesthesia for patients with and without adverse events in the PACU. Three theoretical models were developed to determine the effect of differing rates of adverse events on the requirements for nurses in the PACU. RESULTS: The median workload (PRN points) per patient was 31.0 (25th-75th percentile, 25-46). Median workload was 26 points for patients with no postoperative events and 155 for > or = six adverse events. Workload varied by type of postoperative event (e.g., unanticipated admission to the intensive care unit, median workload = 95; critical respiratory event = 54; and nausea/vomiting = 33). Monitored anesthesia care or general anesthesia with spontaneous ventilation used less resources compared with general anesthesia with mechanical ventilation. Modeling various scenarios (controlling for types of patients) showed that adverse events increased the number of nursing personnel required in the PACU. CONCLUSIONS: Nursing care documentation based on requirements for individual patients demonstrates that the rate of postoperative adverse events affects the amount of nursing resources needed in the PACU.     

Comparison of ropivacaine 0.2% and 0.25% with lidocaine 0.5% for intravenous regional anesthesia

Study ObjectiveTo compare the anesthetic effects of two different concentrations and doses of ropivacaine (0.2% and 0.25%) with those of a conventional dose of lidocaine 0.5%.DesignProspective, randomized, double-blinded, clinical investigation.SettingLarge metropolitan university hospital.Patients66 adult ASA physical status I and II patients undergoing forearm and hand surgery.InterventionsPatients were randomly allocated to three groups to receive intravenous regional anesthesia (IVRA). Study groups were: ropivacaine 0.2% (Group I, n = 22), ropivacaine 0.25% (Group II, n = 22), and lidocaine 0.5% (Group III, n = 22).MeasurementsTourniquet tolerance times and regression of sensory analgesia were noted. Verbal numerical pain scores (VNS), cumulative analgesic consumption, and side effects were recorded during surgery and postanesthesia care unit (PACU). Time to first pain medication intake and number of patients receiving analgesics in the PACU were recorded.Main ResultsAdditional tolerance times for the distal tourniquet were significantly higher in the ropivacaine 0.25% group than the other two groups. Regression of sensory anesthesia was fastest in the lidocaine group. During the PACU stay, VNSs were significantly lower in the first 20 minutes in the ropivacaine groups than the lidocaine group. Time to first intake of pain medication in the PACU was soonest in the lidocaine group. The number of patients given analgesics in the PACU was highest in the lidocaine group. The number of patients taking > two tablets of tramadol was significantly lowest in the ropivacaine 0.25% group. No serious side effects were observed in any study group.ConclusionLonger tolerance times for the distal tourniquet, prolonged analgesia after tourniquet release, and lower analgesic requirements postoperatively make ropivacaine 0.2% and 0.25% an alternative to lidocaine for IVRA.     

后腹腔镜下单侧肾上腺嗜铬细胞瘤摘除术后拔管时间延长

目的比较后腹腔镜下单侧肾上腺嗜铬细胞瘤或其他类型肾上腺肿瘤摘除术后患者的气管导管拔除时间改变。方法回顾性分析我院2014年11月至2017年4月全身麻醉下行后腹腔镜下单侧肾上腺嗜铬细胞瘤摘除术的19例高血压患者的电子麻醉记录单(S组),并选取同期于全身麻醉下行后腹腔镜下单侧肾上腺其他类型肿瘤摘除术的38例高血压患者为对照组(D组)。比较两组患者性别、ASA分级、年龄、身高、体重、手术时长、麻醉时间、术中镇静、镇痛及肌松药用量、拔管时间及PACU滞留时间。结果两组性别、ASA分级、年龄、身高、体重、手术时间及麻醉时间差异无统计学意义。术中镇静、镇痛及肌松药用量差异无统计学意义。S组拔管时间明显长于D组[30.0(25.0~42.5)min vs 20.0(15.0~20.0)min,P0.05]。S组PACU滞留时间亦明显长于D组[70.0(57.5~82.5)min vs 45.0(33.5~55.0)min,P0.05]。结论全身麻醉下行后腹腔镜下单侧肾上腺嗜铬细胞瘤摘除术的患者与同等条件下行肾上腺其他类型肿瘤摘除术的患者比较,术后拔管时间与PACU滞留时间明显延长,可能与术中麻醉药物用量无关。     

Vigilance of hemodynamic changes immediately after transferring patients is crucial

Purpose

A decrease in blood pressure is sometimes observed when a postsurgical patient is transferred to another bed after recovering from anesthesia. However, the mechanism behind this hypotension has not been completely elucidated. The purpose of this study was to investigate and compare changes in hemodynamic properties for possible causes of hypotension before and after transfer to another bed of postsurgical patients receiving general anesthesia, combined epidural and general anesthesia, or combined spinal and general anesthesia.

Methods

We studied 69 patients undergoing elective surgery who were randomized to receive anesthesia by one of the three methods. After surgery, the tracheal tube was removed, and each patient was transferred to another bed. Hemodynamic data recorded immediately before and after transfer of the patient to another bed were compared.

Results

After transfer of patients receiving general anesthesia or combined epidural and general anesthesia, systolic arterial pressure (SAP), diastolic arterial pressure (DAP), and cardiac output (CO) decreased; heart rate (HR) and systemic vascular resistance (SVR) did not change. However, after transfer of patients receiving combined spinal and general anesthesia, SAP, DAP, HR, and CO decreased, but SVR did not change.

Conclusion

The decrease in blood pressure observed after transfer of a postsurgical patient to another bed after general, combined epidural and general, and combined spinal and general anesthesia was associated with a decrease in CO and no change in SVR, but HR decreased after combined spinal and general anesthesia, whereas it was unchanged after general and combined epidural and general anesthesia. The decrease in blood pressure is assumed to be caused by a decrease in venous return, and several reflexes might participate in this decrease of blood pressure, especially after combined spinal and general anesthesia.     

The impact of routine post-anesthesia care unit extubation for pediatric surgical patients on safety and operating room efficiency

PurposeMaximizing operating room (OR) efficiency is essential for hospital cost containment and effective patient throughput. Little data is available regarding the safety and efficacy of extubation of children in the post-anesthesia care unit (PACU) by a nurse rather than in the OR. We sought to evaluate the impact of a long-standing practice of PACU extubation upon airway complications and OR efficiency.MethodsThe records of 1930 children who underwent inguinal hernia repair, laparoscopic appendectomy or pyloromyotomy at a children's hospital between July, 2018 and June, 2020 were reviewed. Extubations were performed in the OR only when the PACU was inadequately staffed or during the early months of the Covid-19 pandemic. Cases in which there was a deep extubation, a PACU hold was in effect or a patient went directly to an inpatient unit from the OR were excluded. Intra- and post-operative time metrics were recorded and emergency airway interventions were assessed.Results1747 operations were evaluated. Time from the end of the procedure to leaving the OR ranged from 4.1 to 4.8 min when extubation was done in the PACU and was 6–9 min less than with OR extubation. (see table). There were 23 airway events (1.5% of all cases) after PACU extubation that necessitated only brief bag-mask ventilation. There were no cases of re-intubation.ConclusionsIn a large population of children undergoing diverse surgical procedures, post-anesthesia care unit extubation was safe and resulted in rapid transfer of patients from the operating room after completion of their operation. Time saved because of shorter operating room times reduces hospital costs and can allow for increased throughput. Extubation in the post-anesthesia care unit may not only be as safe as operating room extubation, but may result in fewer serious airway events as patients may be less likely to have their endotracheal tube removed prematurely.Level of evidenceTreatment Study, Level III     

A prospective study of post-cesarean delivery hypoxia after spinal anesthesia with intrathecal morphine 150 μg

IntroductionDelayed respiratory depression is a feared complication of intrathecal morphine in patients undergoing cesarean delivery. The incidence, timing and risk factors for hypoxia in this population are not known.MethodsPatients undergoing cesarean delivery under spinal anesthesia at a tertiary care center from October 2012 to March 2016 were included in the study. The Berlin sleep apnea Questionnaire was completed before surgery. Oxygen saturation was recorded every second for 24 hours after the initiation of spinal anesthesia. Desaturation events were defined as a median saturation of <90% (mild) or <85% (severe) across a 30-s period. Multivariable logistic regression was used to determine predictors of a desaturation event.ResultsA total of 721 patients were included in the analysis. Within this cohort, 169 women (23%) experienced at least one mild desaturation event, 91 (13%) experienced two or more mild desaturations, and 26 (4%) suffered a severe desaturation event. After the administration of intrathecal morphine, the median times to first mild or first severe desaturation were 7.4 (IQR 4.1–13.5) h and 12.0 (IQR 5.4–19.6) h, respectively. Patients who screened positive for sleep apnea had increased odds of having a mild desaturation event (OR 2.31, 95% CI 1.40 to 3.79, P=0.001), as did patients who were obese (OR 1.80, 95% CI 1.05 to 3.09, P=0.033).ConclusionsMild hypoxemia occurred frequently in women receiving intrathecal morphine 150 μg for post-cesarean analgesia. Desaturations were observed most frequently 4–8 hours after administration of intrathecal morphine. Obesity and a positive Berlin Questionnaire were risk factors for hypoxemic events.     

Supplemental oxygen after outpatient oral and maxillofacial surgery.

Arterial oxygen saturation (SpO2) was monitored postoperatively with pulse oximetry in 72 dental patients. Intravenous general anesthesia was employed in 57 patients. All of these patients received supplemental oxygen intraoperatively, and of these, 29 received supplemental oxygen postoperatively. Fifteen patients received only local anesthesia without supplemental oxygen and served as the control group. Continuous pulse oximetry revealed 43 episodes of arterial oxygen desaturation (SpO2 decreases greater than 3% from baseline) in patients who did not receive postanesthesia supplemental oxygen and eight episodes of desaturation in patients who did receive postanesthesia oxygen. Patients with a smoking history had more episodes of desaturation than did nonsmokers in the group that received general anesthesia and breathed room air postoperatively. The total amount of methohexital administered had no significant effect on the number of patients with desaturation episodes. These observations emphasize the need for postoperative oxygen for patients who undergo general anesthesia for outpatient oral and maxillofacial surgery.