Current Ventilator and Oxygen Management during General Anesthesia: A Multicenter, Cross-sectional Observational Study.

BACKGROUND: Intraoperative oxygen management is poorly understood. It was hypothesized that potentially preventable hyperoxemia and substantial oxygen exposure would be common during general anesthesia. METHODS: A multicenter, cross-sectional study was conducted to describe current ventilator management, particularly oxygen management, during general anesthesia in Japan. All adult patients (16 yr old or older) who received general anesthesia over 5 consecutive days in 2015 at 43 participating hospitals were identified. Ventilator settings and vital signs were collected 1 h after the induction of general anesthesia. We determined the prevalence of potentially preventable hyperoxemia (oxygen saturation measured by pulse oximetry of more than 98%, despite fractional inspired oxygen tension of more than 0.21) and the risk factors for potentially substantial oxygen exposure (fractional inspired oxygen tension of more than 0.5, despite oxygen saturation measured by pulse oximetry of more than 92%). RESULTS: A total of 1,786 patients were found eligible, and 1,498 completed the study. Fractional inspired oxygen tension was between 0.31 and 0.6 in 1,385 patients (92%), whereas it was less than or equal to 0.3 in very few patients (1%). Most patients (83%) were exposed to potentially preventable hyperoxemia, and 32% had potentially substantial oxygen exposure. In multivariable analysis, old age, emergency surgery, and one-lung ventilation were independently associated with increased potentially substantial oxygen exposure, whereas use of volume control ventilation and high positive end-expiratory pressure levels were associated with decreased potentially substantial oxygen exposure. One-lung ventilation was particularly a strong risk factor for potentially substantial oxygen exposure (adjusted odds ratio, 13.35; 95% CI, 7.24 to 24.60). CONCLUSIONS: Potentially preventable hyperoxemia and substantial oxygen exposure are common during general anesthesia, especially during one-lung ventilation. Future research should explore the safety and feasibility of a more conservative approach for intraoperative oxygen therapy.

[Five Cases of Anesthetic Management for Femoral Neck Fracture Repair Complicated with Severe Aortic Stenosis].

Five elderly women complicated with severe aortic stenosis were admitted to our hospital due to femoral neck fracture. Maximum aortic jet velocity was above 5.0 m · s(-1) and aortic valve pressure gradient was above 100 mmHg. Every family wanted to have the fractured femoral neck repaired, despite a high mortality during periop- erative period. We anesthetized the patients with com- bined lumbar plexus and sciatic nerve block and mild sedation. The operation was performed uneventfully. Although one of them sometimes complained chest pain during postoperative period, all five patients could be discharged without catastrophic events. The definition of severe aortic stenosis is above 4.0 m · s(-1) of maximum aortic jet velocity and below 1.0 cm(2) of aortic valve orifice area. As the severity of aor- tic stenosis, increases anesthetic management becomes more difficult and risky. To block the sympathetic nervous system only in the injured leg, we performed combined lumbar plexus and sciatic nerve block at the injured side. Circulatory disturbance was considered to be less than spinal anesthesia. Although the patients suffered from traction pain at the healthy leg and peri- neal region, this method could be chosen in cases of femoral neck fracture repair complicated with severe aortic stenosis.

[A retrospective study on perioperative bleeding in patients for hip fracture surgery in patients treated with or without antiplatelet/anticoagulating drugs].

BACKGROUND: Early operation for hip fracture patients is considered to have better outcome. Therefore, early operation was performed even if patients had been treated with antiplatelet and/or anticoagulating drugs (AP/AC) in our hospital for the past two years. This retrospective study was undertaken as excessive blood loss is expected in patients treated with AP/AC. METHODS: Elderly patients for hip fracture surgery were retrospectively studied in our hospital for the past two years. Perioperative decrease in hemoglobin level and the incidence of transfusion were compared between patients treated with AP/AC and those not treated. RESULTS: Sixty-four patients were treated with AP/AC and one hundred ninety-nine patients were not treated. Patients treated with AP/AC had more preoperative complications and worse ASA-PS scores. General anesthesia was used more frequently for patients with AP/AC. In the perioperative decrease in hemoglobin level and the incidence of transfusion, there were no significant differences between the groups. CONCLUSIONS: Perioperative bleeding for hip fracture surgery was compared between patients treated with and without AP/AC. No significant difference was observed, and, discontinuation of AP/AC might not be necessary for hip fracture surgery.

[Asystole after anesthetic induction with remifentanil].

A 45-year-old man was scheduled for laparoscopic cholecystectomy. He had hypertension controlled with beta-adrenergic, calcium channel and angiotensin II receptor blocking agents. Because he had complications of symptomatic cervical spondylosis and sleep apnea syndrome, we performed awake fiberoptic intubation with remifentanil at a dose of 0.05 microg x kg(-1) min(-1). After intubation and following administration of propofol and vecuronium, ECG unexpectedly changed to asystole. We administered atropine 1.5 mg and performed chest compressions, which successfully restored sinus rhythm within 10 seconds. However, no cardiac disease was detected by a cardiologist. The operation was scheduled a week later again. Anti-hypertensive agents were discontinued. A temporary pacing wire was inserted before surgery, and atropine 0.5 mg was administered before anesthetic induction with remifentanil. No cardiac event was noticed through the perioperative period. We suggest that even a low dose of remifentanil may cause asystole in patients taking beta-adrenergic and calcium channel blocking agents, and preemptive administration of atropine may be effective.

[Anesthetic management of patients 100 years of age and above undergoing emergency abdominal surgery].

We anesthetized four patients aged 100 years and above who underwent emergency abdominal surgery. Case 1 : A 100-year-old woman with ileus caused by rectal cancer had chronic heart failure in whom colostomy was performed. Case 2 : A 101-year-old man with incarceration of inguinal hernia and history of cerebral infarction. Hernioplasty was performed. Case 3 : A 100-year-old woman with duodenal perforation and hypertension, in whom patching was performed. Case 4 : A 100-year-old bedridden man with incarceration of inguinal hernia who had enteral nutrition through gastrostoma, in whom hernioplasty was performed. General anesthesia was performed mainly with sevoflurane and all patients were discharged without any critical complications. Anesthetic management of elderly patients requires appropriate preoperative evaluation according to their complicating diseases, consciousness, activities of daily living and nutrition. Especially for patients aged 100 years and above, their quality of life should be evaluated. Surgical indication and procedure should be determined accordingly.

[Which anesthetic technique is more suitable for hip fracture surgery in patients above the age of 85, spinal or epidural?].

BACKGROUND: Anesthesia for hip fracture in elderly patients is a challenge because of their reduced functional reserve. We compared spinal and epidural anesthesia retrospectively in the operations of hip fracture in patients above the age of 85. METHODS: Two hundred and eighteen operations from April 1995 to September 2003 in our hospital were examined. Epidural anesthesia was scheduled in 94 operations, and bupivacaine spinal anesthesia in 86 operations. Successful anesthetic cases of each group were compared. Blood pressure, heart rate, doses of vasopressors used were recorded before anesthesia and first and second 30-minute periods after anesthesia. RESULTS: Failed anesthetic cases in epidural anesthesia were significantly more than those in spinal anesthesia. Blood pressure in the first 30-minute period after epidural anesthesia was significantly lower than that after spinal anesthesia. CONCLUSIONS: Spinal anesthesia is preferable for the operation for hip fracture compared with epidural anesthesia, because of fewer failed cases and smaller decreases of blood pressure.

[Combined paravertebral lumbar plexus and parasacral sciatic nerve block for reduction of hip fracture in four patients with severe heart failure].

We experienced four cases of anesthesia for hip fracture reduction in patients with severe heart failure, where anesthesia was attempted with combined paravertebral lumbar plexus and parasacral sciatic nerve block instead of spinal anesthesia. The anesthesia was successful without any sequelae. The patients' characteristics are as follows. Case 1: 97-year-old woman with severe heart failure and old myocardial infarction. Case 2: 91-year-old man with pacemaker, heart failure and heart valve disease. Case 3: 93-year-old woman with severe heart failure and multi-vessel coronary artery stenosis. Case 4: 83-year-old woman with congestive heart failure and heart valve disease. Paravertebral lumbar plexus block was performed with Touhy needle which was directed to lumbar transverse process, then re-directed caudally. Psoas compartment was felt with loss of resistance. Twelve ml of 0.25% bupivacaine was injected. Sciatic nerve block was performed with a needle which was inserted at the midpoint between the greater trochanter and the sacral hiatus without (case 1, 2) or with nerve stimulator (case 3, 4). Eight ml of 0.25% bupivacaine was injected. During the anesthesia, propofol was injected for light sedation. Although this combined nerve block is difficult to perform compared with spinal anesthesia, this could be applicable for hip fracture reduction anesthesia, especially in patients with severe heart failure.

[A case of re-expansion pulmonary edema after one lung ventilation for the radical operation of lung cancer].

A 64-yr-old man was admitted to our hospital for the examination of the abnormal shadow in his left lung field, which was diagnosed later as lung cancer. Radical operation was scheduled under combined epidural/general anesthesia. One lung ventilation was performed to facilitate the operative procedure for two hours and fifteen minutes. About two hours after the re-expansion of his left lung, he complained of dyspnea. He was hypoxic and moist rale was audible in his left lung. Cloudy shadow emerged in the left field of his chest X-P. Under bronchofiberoptic observation, excessive serous secretions was seen, but no obstructive lesions were found in his bronchial tree. Re-expansion pulmonary edema was suspected for these findings. It was improved with mechanical ventilation with PEEP. Re-expansion pulmonary edema seldom occurs in one lung anesthesia. Although radical operation of esophageal cancer performed six years before might have induced the development of re-expansion pulmonary edema in our case, complete collapse with quick re-expansion of the lung is clearly a potential risk of re-expansion pulmonary edema. Careful management is necessary after one lung ventilation.