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L A Critchley

Publications and source records attributed to L A Critchley.

43 records · Page 3Linked to original sources
PubMed1994

Hypotension during subarachnoid anaesthesia: haemodynamic analysis of three treatments.

We have compared three methods of preventing hypotension during subarachnoid anaesthesia. We attempted to maintain systolic arterial pressure (SAP) greater than 75% of baseline by use of i.v. fluids (preloading with normal saline 16 ml kg-1 and, if necessary, three subsequent boluses of 2.5 ml kg-1), an infusion of metaraminol titrated as necessary between 0 and 5 mg h-1 and an infusion of ephedrine titrated as necessary between 0 and 120 mg h-1. SAP and mean arterial pressure (MAP) were measured by automated oscillotonometry, central venous pressure (CVP) by a manometer and cardiac index (CI), stroke index (SI) and heart rate (HR) by transthoracic electrical bioimpedance. Systemic vascular resistance index (SVRI) was derived. Fluids alone failed to maintain SAP in five of 10 patients. Although CI and CVP were maintained, SVRI decreased (25 (SD 15)%; P = 0.02). Metaraminol maintained SAP in all 12 patients. The main cardiovascular change was decreased HR (15 (8)%; P = 0.0001). Ephedrine failed to maintain SAP in two of 12 patients and was accompanied by several cardiovascular changes: HR (21 (12)%; P = 0.001) increased and SI (16 (10)%; P = 0.0001), CVP (3.8 (1.5) cm H2O; P = 0.0001) and SVRI (24 (6)%; P = 0.0001) decreased. Treatment failures resulted from failures to maintain SVRI in the fluid group and CVP and SVRI in the ephedrine group.

Aged↗
PubMed1994

Haemodynamic effects of subarachnoid block in elderly patients.

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).

Aged↗
PubMed1994

Ondansetron 4 mg for the prevention of nausea and vomiting after minor laparoscopic gynaecological surgery.

We studied the efficacy and safety of intravenous ondansetron 4 mg for the prevention of postoperative nausea and vomiting after minor gynaecological laparoscopic surgery in Oriental women. This double-blind randomised study compared ondansetron with placebo, given before the induction of anaesthesia. The anaesthetic technique used thiopentone, fentanyl, atracurium, nitrous oxide and isoflurane. Patients were studied for 24 h with nausea assessed using a verbal numeric scale from 0-10 and emetic episodes recorded as they occurred. Results were available for 102 patients in each group. In the first postoperative hour, fewer patients in the ondansetron Group (12%) had emetic episodes compared with the placebo group (33%, P < 0.01). Nausea score over the first hour (sum of three readings at 0, 30 and 60 min) was lower in the ondansetron group (median 1.6) compared with the placebo group (3.1, P < 0.05). Over the 24 h period, fewer patients in the ondansetron group had emetic episodes (25%) or nausea (43%) compared with patients in the placebo group (56%, P < 0.01) and (58%, P < 0.05) respectively. No adverse events were seen. Ondansetron 4 mg was more effective than placebo in preventing postoperative nausea and vomiting throughout the 24 h after minor laparoscopic surgery.

Adult↗
PubMed1993

Haemodynamic changes in patients undergoing laparoscopic cholecystectomy: measurement by transthoracic electrical bioimpedance.

Using transthoracic electrical bioimpedance with the BoMed NCCOM3-R7, we measured cardiovascular changes in 16 ASA I and II Chinese patients undergoing laparoscopic cholecystectomy. The peritoneal cavity was insufflated with carbon dioxide to a pressure up to 15 mm Hg. Tidal volume, minute volume and end-tidal carbon dioxide partial pressure were kept constant. Insufflation resulted in a mean (SD) 13 (14)% decrease in stroke index (SI) (P < 0.01), but the effect on cardiac index (CI) was more variable (mean 7 (17)% decrease, range 36% decrease to 22% increase (P = 0.07)). Mean arterial pressure increased by 55 (29)% (P < 0.001) and systemic vascular resistance index increased by 63 (33)% (P < 0.001), with the maximum effect occurring 10-15 min after the commencement of insufflation. Multiple regression analysis showed a greater decrease in SI in patients with a small body mass index and large intraperitoneal pressure (P = 0.01), while a greater decrease in CI was found in patients with a small body mass index and younger age (P = 0.001). Three patients had a further reduction in CI during surgery, with one patient having a 48% decrease compared with pre-induction values. Deflation of the peritoneum resulted in an increase in both CI (25 (26)%) and (22 (29)%) (P < 0.01) to values which were not different from pre-induction data. Arterial blood-gas analysis showed decreases in pH and base excess after 1 h of insufflation (P < 0.01).

Adult↗
PubMedDate not supplied

Spectral analysis of sudden bradycardia during intrathecal meperidine anesthesia.

BACKGROUND AND OBJECTIVES: Severe bradycardia occurring suddenly during spinal anesthesia, although rare, is potentially fatal. Bradycardias are more common after intrathecal meperidine. We report two such episodes occurring in elderly male patients undergoing transurethral surgery. METHODS: Subarachnoid block was provided using 50 mg meperidine. Autonomic function was assessed by measuring heart rate (HR) variability using R-R intervals from standard electrocardiographic recordings. Frequency-domain spectra were constructed from 512 heartbeats, and an autoregressive method was used to calculate spectral power. RESULTS: In both patients, bradycardia (HR <50 beats/min) occurred after about 10 minutes and was associated with severe hypotension and a 10- to 100-fold increase in spectral density in both the low (0.04-0.15 Hz), mainly sympathetic, and the high (0.15-0.40 Hz), mainly parasympathetic, frequency bands. These spectral increases were subsequently attenuated by intravenous atropine. Heart rate slowing was noted to be periodic, or oscillatory, in one patient. CONCLUSION: Sudden increases in vagal, or parasympathetic, activity probably accounted for bradycardia.

Adjuvants, Anesthesia↗