Introduction

The combined spinal–epidural (CSE) technique produces reliable and rapid onset of spinal anesthesia combined with the flexibility to extend the height and duration of a block provided by continuous epidural anesthesia. CSE has become a popular technique in both obstetrics and orthopedic surgery. CSE was originally described in 1979 as a double-segment technique with the epidural and spinal procedures performed at different interspaces of the lumbar spine. Advances in needle design led to the more popular and practical single-segment technique (SST) in use today. In 1981 clinicians described the use of the SST for lower limb surgery and in 1982 for cesarean section.

The SST involves locating the epidural space with either a standard or a specialized epidural needle using the loss of resistance technique. Once the epidural space has been identified, a small-gauge spinal needle is introduced via the epidural needle into the cerebrospinal fluid. A spinal dose of opioid or local anesthetic (or both) is given through the spinal needle, and then the spinal needle is removed. An epidural catheter is then inserted through the epidural needle to the appropriate depth. The technique can be performed in the sitting or lateral position.

Options/Therapies

The CSE technique is widely used for labor analgesia, anesthesia for cesarean section, lower-extremity orthopedic surgery, and urologic procedures. Once popular, the role of CSE in lower-extremity vascular procedures has declined secondary to the use of antithrombotic and antiplatelet therapies for the treatment of vascular disease.

CSE produces a rapid onset of analgesia for the woman in advanced labor while simultaneously maintaining the maternal ability to push during the second stage. In early labor, an initial dose of intrathecal opioid alone maintains maternal mobility and may increase the speed of cervical dilation. Concurrent placement of the epidural catheter enables additional doses of local anesthetic with or without opioid to produce prolonged labor analgesia or cesarean section anesthesia.

CSE for cesarean section provides the benefit of a quick onset of neuraxial blockade with the ability to use the epidural if the spinal block recedes or the surgery is unexpectedly prolonged. Secondarily, the epidural can be used to provide postoperative analgesia with both low-dose local anesthetics and epidural opioids.

In orthopedic procedures, the CSE technique is used in lower-extremity surgeries, such as total hip and total knee arthroplasties. The technique can be as efficient as a general anesthetic, may reduce the incidence of postoperative deep vein thrombosis, and can be used for postoperative analgesia in the absence of antithrombotic therapy.

The low-dose sequential CSE technique is a modification of the original technique that uses a deliberately subanesthetic intrathecal dose with the expectation of extending the block height by the subsequent epidural injection of either local anesthetic or saline. This technique has been shown to enhance cardiovascular stability in high-risk cases, including pregnant women with severe pre-eclampsia.

Contraindications

Patients receiving a CSE must be appropriate candidates for a neuraxial technique. Contraindications include patient refusal, coagulopathy, and some infections. American Society of Regional Anesthesia and Pain Medicine (ASRA) guidelines recommend that a patient have normal coagulation status before undergoing instrumentation of the neuraxis. Aspirin or nonsteroidal antiinflammatory agent therapy is not a contraindication; however, other antiplatelet therapies such as clopidogrel require cessation 7 days before undergoing the procedure. Patients taking warfarin should go 5 days without therapy or have a current normal prothrombin time (PT) and international normalized ratio (INR). Patients receiving prophylactic doses of low-molecular-weight heparin (LMWH), such as 30 to 40 IU enoxaparin or 5000 IU dalteparin every 24 hours, must wait 12 hours after the last dose before undergoing neuraxial blockade. Patients receiving therapeutic doses of LMWH, such as 1 mg/kg enoxaparin every 12 hours, 1.5 mg/kg enoxaparin daily, 120 U/kg dalteparin every 12 hours, 200 U/kg dalteparin daily, or 175 U/kg tinzaparin daily, must wait 24 hours from the last dose before receiving a neuraxial block. Direct thrombin inhibitors such as argatroban are contraindicated until more data are available. Subcutaneous heparin is not a contraindication to regional anesthesia.

Evaluating the coagulation status of the obstetric patient can present a special challenge. Pregnancy may be complicated by conditions that lower the platelet count or inhibit platelet function such as pre-eclampsia, eclampsia, or the syndrome of hemolysis, elevated liver enzymes, and low platelets (HELLP syndrome). Given the hypercoaguable condition of pregnancy, the absolute platelet count is less concerning than the trend in platelet numbers. There is no evidence for a specific platelet count below which neuraxial techniques are contraindicated in the obstetric patient. Thus it would seem, as a practical matter, that a risk–benefit assessment should be undertaken for any pregnant woman with a platelet count of less than 75,000/mm ³ or with a sudden, substantial drop from her baseline, and an individualized decision should be reached regarding the safety of a neuraxial technique. Patients with a platelet count less than 75,000/mm ³ should be examined for stigmata of coagulopathy (easy bruising, petechiae, bleeding from the intravenous site or Foley catheter) before instrumentation. A PT, a partial thrombin time, and a platelet count should be reviewed before proceeding. If any of the aforementioned test results are abnormal, a fibrinogen level and a d-dimer level are useful in assessing the patient for the presence of disseminated intravascular coagulation.

Obstetric patients may be receiving anticoagulation therapy for a variety of obstetric or nonobstetric indications. Ideally, women taking long-acting anticoagulants (e.g., for deep vein thrombosis prophylaxis or prosthetic heart valves) should be converted from their long-acting therapies (e.g., LMWH) to subcutaneous heparin at 36 weeks of gestational age. A patient taking therapeutic LMWH who is in labor must wait a minimum of 24 hours from the last dose before undergoing CSE analgesia or anesthesia.

Patients with infection at the needle insertion site, suspected meningitis (bacterial or viral), or sepsis should not undergo neuraxial blockade. Patients with suspected chorioamnionitis can receive regional anesthesia after the administration of appropriate intravenous antibiotics. Parturients with a primary herpes simplex outbreak are at increased risk of herpetic meningitis with neuraxial techniques. Human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) is not a contraindication to CSE.

Evidence Favoring the Use of Combined Spinal–Epidural Technique