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.

[Acute pulmonary thromboembolism after multiple injuries, despite performing anticoagulant therapy].

We report here a patient with acute pulmonary thromboembolism after multiple injuries, despite performing an anticoagulant therapy precisely according to a guideline. A 56 year-old-woman with multiple fractures was transferred after a motor vehicle accident. She was diagnosed with a pelvic fracture, a left clavicular fracture, and a right radius fracture. For preventing deep vein thrombosis DVT, elastic stockings were attached immediately on arrival. Then we started administration of unfractionated heparin on the second day. An operation was performed for the left clavicular fracture and the right radius fracture on the fifth day. We restarted subcutaneous injection of heparin on the sixth day and 1 mg day(-1) of warfarin was added from the ninth day. On the 12th day, sudden dyspnea suggested acute pulmonary embolism and a pulmonary arteriography confirmed occlusion of the left main pulmonary artery with thombocyte. Interventional anti-thorombotic procedure was performed, and she was discharged with no complications on the 72nd day. Despite "A Guideline for Prevention of Venous Thromboembolism", arranged in Japan, was issued in June 2004, it is difficult for us to prevent DVT at the recovery phase as in this case. The guideline should be revised after further examinations.

[Combined spinal-epidural anesthesia for cesarean section in a patient with dilated cardiomyopathy].

We report successful anesthetic management of elective cesarean section in a 31-year-old patient with dilated cardiomyopathy (DCM) using combined spinal-epidural anesthesia (CSEA). After inserting an arterial catheter and central venous catheter, isobaric bupivacaine (0.5% ; 5 mg) with fentanyl 10 microg was injected intrathecally at the L4-5 interspace under administration of dopamine 3 microg kg(-1) min(-1). 10 min and later, a total of ropivacaine (0.5%; 70 mg) with fentanyl 50 microg was titrated at 2-3 min intervals through the epidural catheter inserted at the L1-2 interspace resulting in analgesic level of T4 25 min after induction of spinal anesthesia. A baby was delivered uneventfully with good Apgar score, and the patient's perioperative hemodynamic change was minimal. CSEA is a reliable, titratable technique, which provides excellent analgesia with minimal hemodynamic changes for patients with DCM undergoing cesarean section.

[Acute pulmonary thromboembolism during the surgery for bilateral lower extremity fracture].

A 50-year-old woman underwent open reduction and internal fixation for bilateral lower extremity fracture under general anesthesia. During the surgery, arterial oxygen saturation and expired CO2 concentration dropped suddenly when the left limb was fixed. Immediately, we performed aspiration of the pulmonary thrombus and inserted a temporary infra-vena cava filter followed by heparinization. Ten days later, we carried out the surgery on the right limb uneventfully. The major cause of APTE is deep vein thrombosis (DVT), which is extremely common during perioperative period. Therefore, we must perform antithrombotic therapy for the patient at high risk for DVT.

[Anesthetic management of a child with Schwartz-Jampel syndrome].

A 6-year-old child with Schwartz-Jampel syndrome (SJS) underwent tenotomy of bilateral lower limbs under general anesthesia. Patient with SJS has problems such as difficulty of intubation owing to microstomia and jaw muscle rigidity, and is susceptible to malignant hyperthermia by using volatile inhalation anesthetics. In this case, we used a laryngeal mask for airway management and anesthesia was maintained with inhalation of nitrous oxide and continuous i.v. infusion of propofol with caudal block, and his clinical course was uneventful.

Feasibility study of immediate pharyngeal cooling initiation in cardiac arrest patients after arrival at the emergency room.

AIM: Cooling the pharynx and upper oesophagus would be more advantageous for rapid induction of therapeutic hypothermia since the carotid arteries run in their vicinity. The aim of this study was to determine the effects of pharyngeal cooling on brain temperature and the safety and feasibility for patients under resuscitation. METHODS: Witnessed non-traumatic cardiac arrest patients (n=108) were randomized to receive standard care with (n=53) or without pharyngeal cooling (n=55). In the emergency room, pharyngeal cooling was initiated before or shortly after return of spontaneous circulation by perfusing physiological saline (5 °C) into a pharyngeal cuff for 120 min. RESULTS: There was a significant decrease in tympanic temperature at 40 min after arrival (P=0.02) with a maximum difference between the groups at 120 min (32.9 ± 1.2°C, pharyngeal cooling group vs. 34.1 ± 1.3°C, control group; P<0.001). The return of spontaneous circulation (70% vs. 65%, P=0.63) and rearrest (38% vs. 47%, P=0.45) rates were not significantly different based on the initiation of pharyngeal cooling. No post-treatment mechanical or cold-related injury was observed on the pharyngeal epithelium by macroscopic observation. The thrombocytopaenia incidence was lower in the pharyngeal cooling group (P=0.001) during the 3-day period after arrival. The cumulative survival rate at 1 month was not significantly different between the two groups. CONCLUSIONS: Initiation of pharyngeal cooling before or immediately after the return of spontaneous circulation is safe and feasible. Pharyngeal cooling can rapidly decrease tympanic temperature without adverse effects on circulation or the pharyngeal epithelium.