In hip surgery, hemodynamic stability may be affected even with the use of low-dose, single-shot spinal anesthesia (SSA). However, the SSA may fail leading to the option for the use of titrated continuous spinal anesthesia (CSA) or combined low-dose spinal epidural (SE).

We aim to present a systematic review about the use of different techniques utilizing a low-dose spinal block in hip surgery, in terms of efficacy and hemodynamic stability but also including other outcomes.

The last PubMed database (Medline) search was conducted in June 2021. The complete search strategy was as follows: [(low dose spinal anesthesia) OR (combined spinal epidural anesthesia) OR (continuous spinal anesthesia)] AND (hip). Additional articles were searched in the reference list of the included articles from the PubMed database search.

To be included in this review, studies had to meet the following criteria: 1) written in English; 2) performed in 1980 or later; 3) detailed anesthetic management provided; 4) hemodynamic evaluation did not have to be the primary outcome; 5) randomized controlled trial (RCT) or large retrospective study.

“Low-dose spinal anesthesia” and “ultra-low-dose spinal anesthesia” were defined by the authors as follows: levobupivacaine or bupivacaine ≤7.5 and 5 mg; lidocaine ≤75 and 50 mg; tetracaine ≤7.5 mg and 5 mg; and prilocaine ≤30 mg and 20 mg, respectively, administered ad initium (or as a single-shot spinal block) in the different techniques.

In order to minimize the inclusion of very low evidence studies we opted for the inclusion of only RCTs and large retrospective cohort studies and we avoided the inclusion of case reports and small case series (involving less than 10 patients). We did not undertake a meta-analysis to minimize the risk of bias, due to the heterogeneity of the population involved in each type of surgery. The publications are listed according to the type of surgery. Studies including a mix of lower limb surgery involving the hip joint and knee joint, even if they included mostly hip surgery, were not included.

Commentaries, correspondences, and letters to the editor without specific patient data were not included. The Jadad score, bias risk or Grading of Recommendations and Assessment, Development and Evaluation (GRADE) system levels of evidence were established.

Nineteen studies were included in the final analysis. Titrated CSA was the technique most frequently studied. SSA with doses ≤5 mg of bupivacaine for hip fracture surgery was successfully reported in two studies. In most studies, titrated CSA was associated with lower consumption of vasopressors compared to standard dose SSA and, in one study, to moderately low-dose SSA. In one study, ultra-low SSA was hemodynamically superior to low-dose SSA in hip fracture patients.

All studies involving the use of low-dose SSA, combined low-dose SE, or titrated CSA reported lower consumption of vasopressors compared to standard dose SSA. The rate of conversion to general anesthesia was low in every technique. This systematic review may present limitations because, for instance, it may not include studies on the efficacy of neuraxial blocks combined with general anesthesia.