Haemodynamic effects of subarachnoid block in elderly patients

Abstract

We have studied the haemodynamic effects of subarachnoid block in elderly patients. Thirty patients were undergoing elective transurethral surgery and 18 non-elective orthopaedic surgery, predominantly fractured neck of femur. Systolic arterial pressure (SAP) was measured by automated oscillotonometry, central venous pressure (CVP) by manometer and cardiac index (CI), stroke index (SI) and heart rate (HR) by transthoracic electrical bioimpedance. Systemic vascular resistance index (SVRI) was derived. SAP decreased by more than 25% in 33 patients and SVRI showed similar decreases (P = 0.0001). CVP decreased (2.5 (SD 1.5) cm H2O) in all patients. CI was unaffected because a decrease in SI in some patients (13 (19)%; P = 0.01) was compensated for by an increase in HR (13 (13)%; P = 0.01). Decreases in SAP of 25% were treated initially with colloid solution 8 ml kg-1, which restored SAP in 19 patients. CVP, SI and HR were all restored to baseline values, however, SVRI was decreased further (P < 0.05). Fourteen patients required additional treatment with metaraminol which restored SVRI to baseline values. Patients with systolic hypertension were more likely to require treatment with metaraminol (P = 0.04).

A comparison of the haemodynamic effects of intrathecal meperidine, meperidine-bupivacaine mixture and hyperbaric bupivacaïne

“…We used hyperbaric bupivacaine 15 mg for our control group, because we had used this dosage in previous studies. [27][28][29] Preloading before intrathecal injection was omitted from the study, as this would have affected our assessment of venous pressures. However, no patient was admitted to the study dehydrated and any hypotension was promptly treated.…”

Epidural meperidine does not cause hemodynamic changes in the term parturient

“…Cardiac output (CO) and heart rate (HR) were measured continuously using the BoMed NCCOM3-R7S (BoMed Manufacturing, Irvine, CA, USA) and these data were uploaded to a laptop computer, as described in previous studies. 5,8,9 The BoMed NCCOM3 was connected to the patient using an eight electrode montage to the neck and lower thorax. 10 Fetal well being was continuously monitored using a cardiotocograph, and regularly assessed by a midwife present for the duration of the study.…”

“…Hemodynamic data were analysed using methods similar to those used in our previous studies of hemodynamic changes associated with spinal anesthesia. 5,8,9 The BoMed produced a cardiac output and heart rate measurement every 16 heartbeats, and these were averaged to produce mean values for each twominute time period. To allow time for the hemodynamic changes associated with epidural meperidine to become established, only data collected during the second half (10 min), following each epidural injection were analysed.…”

Impedance cardiographyThe impact of new technology

“…Poorer correlation has been found during abdominal surgery, which has been discussed previously [11,40]. Impedance cardiography has also been used successfully as a research tool to measure changes in cardiac output during induction of anaesthesia and tracheal intubation [41,42], laparoscopic cholecystectomy [43,44] and spinal anaesthesia [45,46]. There are few published data on the use of TEB to monitor changes in lung fluid content during surgery.…”