Aging and frailty make the elderly patients susceptible to hypotension following spinal anaesthesia. The systemic haemodynamic effects of spinal anaesthesia are not well known. In this study, we examine the systemic haemodynamic effects of fractional spinal anaesthesia following intermittent microdosing of a local anesthetic and an opioid.

We included 15 patients aged over 65 with considerable comorbidities, planned for emergency hip fracture repair. Patients received a spinal catheter and cardiac output monitoring using the LiDCOplus system. Invasive mean arterial pressure (MAP), cardiac index, systemic vascular resistance index, heart rate and stroke volume index were registered. Two doses of bupivacaine 2,25 mg and fentanyl 15µg were administered with 25 minutes in between. Hypotension was defined as a fall in MAP by >30% or a MAP <65 mmHg

We daily screened patients planned for hip fracture surgery and these were identified through the theatre planning software (Orbit, TietoEVRY, Espoo, Finland). Nottingham Hip Fracture Score was calculated. This scoring system includes objective factors like age, sex, dementia, previous cancer, living facility and comorbidity. NHFS varies from 1-10 with higher numbers correlated to higher 30-day mortality. ASA grade was also recorded after study inclusion.

After arriving to the preoperative area, patients were given 5 liters of oxygen on a face mask and ECG and pulse-oximetry monitoring were started. Oral premedication with standardized doses of paracetamol and oxycodone was given orally, followed by the placement of a venous 18G cannula in an antecubital vein and a radial arterial catheter (20G). The patient was also given a fascia iliaca compartment (FIC) block, or an ultrasound guided femoral nerve block with ropivacaine 3.5mg/ml 20-40ml, to decrease discomfort when given the neuraxial block. In addition, the LiDCOplus (LiDCO Group Plc, London, England) system was set up according to manufacturer's instructions. The system was calibrated with 0.3-0.45 mmol lithium chloride depending on body weight. After calibration and baseline parameter registration, the LiDCOplus system provided cardiac output variables and based on these and the invasive blood pressure, haemodynamic variables could be derived.

Following aseptic skin preparation of the lumbar area, a subarachnoid puncture by a 18G Tuohy needle was performed either between the L2 - L3 or the L3 - L4 interspaces, preferably using a mid-line approach. An intrathecal catheter 20G was then inserted 4-5 cm into the intrathecal space. This technique of a continues spinal anaesthesia (CSA) was performed on all patients by one physician (FO). A solution (10 ml) containing 1.5 mg/ml bupivacaine and 10 µg/ml fentanyl was prepared. Intrathecal anaesthesia was induced by giving 1,5 ml (2.25 mg of bupivacaine and 15 µg of fentanyl) of the solution, followed by a second 1.5 ml injection after 25 min (i.e., a total intrathecal dos of 4.5 mg of bupivacaine and 30 µg of fentanyl). Sensory level was monitored by "cold spray". Hemodynamic recordings were performed every 5 minutes up until 45 minutes after initial intrathecal dose when research monitoring was terminated. The patient was then operated in the pre-planned time slot and was further managed at the discretion of the attending anesthetist.

Inclusion Criteria:

1. patient with hip fracture,
2. >65 years of age,
3. ASA ≥2, 4) scheduled for neuraxial anaesthesia and 5) mentally intact to give informed consent. This could also be given by next-of-kin, if the patient was cognitively impaired.

Exclusion Criteria:

1. lithium or anticoagulation medication,
2. planned for general anaesthesia,
3. ongoing atrial fibrillation,
4. if surgery was delayed >72 hours,
5. lack of informed consent and
6. patient agitation requiring intermittent sedation.

The number of participants is low and anonymity would be difficult to guarantee.