两个还是三个并列？

Most vertebral augmentation procedures are performed under a combination of moderate conscious sedation and local anaesthesia although some operators continue to prefer the use of general anaesthesia. Moderate sedation allows the patient to give feedback (such as worsening pain or neurologic symptoms) that may alert the practitioner to complications. Local anaesthetic, typically lidocaine or bupivacaine, is infiltrated to the skin, subcutaneous tissues and periosteum along the needle tract and bone entry point. The patient may experience additional discomfort during injection of the PMMA cement; intravenous analgesia may be required in these cases. General anaesthesia is used in rare cases where conscious sedation is contraindicated, such as in those with severe pain, high requirements for narcotic analgesia or the inability to tolerate prone positioning for prolonged periods.All cases require continuous cardiopulmonary monitoring with blood pressure measurements, electrocardiography and pulse oximetry. Patients with significant cardiac or pulmonary disease may require evaluation by an anaesthesiologist to determine if additional monitored anaesthetic care is necessary. In all patients, fasting from food and drink is required for at least 6 hours prior to vertebral augmentation.

大多数椎体充填扩张术是在局部麻醉加强化下进行，尽管某些术者采用全身麻醉的方式进行。中度镇静可时时了解患者的反馈（如疼痛恶化或神经症状恶化），可提醒术者关注并发症。通常沿着针道和骨入点局部浸润麻醉药物（利多卡因或布比卡因）到皮肤、皮下组织和骨膜。患者在注射PMMA时可能会感到不适，这时可能需要静脉镇痛。当手术禁忌局麻的罕见情况时（如因严重的疼痛，麻醉镇痛要求高，或是无法耐受长时间俯卧位的患者）可全身麻醉。患者需要通过心电图、脉搏血氧饱和度和心电监护来心肺监测。为确定是否需要额外的麻醉监护，有严重心肺疾病的患者需要麻醉医师详细评估。患者在术前至少6小时禁食和水。

severe pain, high requirements for narcotic analgesia or the inability to tolerate prone positioning for prolonged periods.

两个还是三个并列？