Restricted spinal anaesthesia for ambulatory surgery: a pilot study.

The increasing use of ambulatory surgery requires methods of anaesthesia that allow patients to be discharged soon after the operation is completed. Spinal anaesthesia is usually simple and quick, and the incidence of post-spinal headache has been reduced by using non-cutting small-gauge needles. Limiting the spread of spinal anaesthesia, as long as it still provides analgesia for surgery, should reduce the haemodynamic effects and speed recovery. Restricted spinal anaesthesia, intended to be unilateral using 0.18% hypobaric bupivacaine via a 25G or 27G Whitacre unidirectional needle, was compared with epidural anaesthesia (using a mixture of lignocaine and prilocaine) in 64 matched-pair patients undergoing ambulatory arthroscopy. Motor blockade, assessed for the specific myotomes L2 to S1, was significantly more unilateral in the spinal group. Two patients in the spinal group and nine patients in the epidural group were treated for hypotension (P < 0.05). One patient in the spinal group developed a post-spinal headache. One patient in the epidural group rated the anaesthesia poor.

Biochemical and clinical assessment of histamine blockade.

The effects of antihistamines on biochemical stress indicators and on psychomotor and physiological functions were studied in 60 healthy patients receiving in a randomized, double-blind study either 25 mg promethazine, 150 mg ranitidine, both drugs or placebo (n = 15 in each group). Different aspects of the premedications were evaluated by determining various hormone, neurotransmitter and neurotransmitter metabolite levels in blood and cerebrospinal fluid, and subjectively using questionnaires concerning the quality of the preoperative night's sleep and visual analogue scales, and objectively by measuring changes in blood pressure and heart rate, impairment of vigilance with the Maddox wing apparatus and the critical flicker fusion threshold test. The relationships between the subjective assessments and the biochemical stress indicators were also investigated. There were no differences between the study groups in the quality of the preoperative night's sleep, estimated fear, apprehension or dizziness, or in the various physiological stress indicators. Only few statistically significant correlations were found between the subjective and biochemical assessments. It is concluded that histamine receptor antagonists used in clinical doses do not interfere with the biochemical, clinical preoperative, and physiological responses.

Monoamine metabolite and catecholamine measurements in cerebrospinal fluid in determining the quality of the pre-operative night's sleep.

Temazepam 20 mg (n = 18), midazolam 15 mg (n = 14), placebo (n = 15) or no medication (n = 20) were given orally as pre-operative hypnotic in healthy patients operated on under spinal analgesia. The quality of the pre-operative night's sleep assessed subjectively was significantly better in patients receiving temazepam (P = < 0.05) and midazolam (P = < 0.05) compared with those receiving no drug. The concentrations of cortisol and monoamine neurotransmitters or their metabolites in cerebrospinal fluid were of no value in monitoring the quality of the pre-operative night's sleep.

Temazepam or midazolam for night sedation. A double-blind study.

The effects of oral temazepam (20 mg), oral midazolam (15 mg) and a placebo were compared for night sedation on the evening prior to surgery in a double-blind study. Patients in the placebo group had significantly worse sleep than those in the temazepam (p = 0.004) or midazolam groups (p = 0.04). There was no significant difference between the two drug groups, nor between the residual effects of the three treatments. Temazepam appears to be somewhat more effective than the ultrashort-acting midazolam in pre-operative transient insomnia.

Temazepam versus flunitrazepam as an oral premedication in adult surgical patients.

In a randomized study, 20 patients received temazepam 20 mg orally the night before and 20 mg in the morning of an operation performed under spinal analgesia (Group I); 20 patients received flunitrazepam I mg similarly (Group 2). Different aspects of the premedication were evaluated verbally, with the aid of a visual analogue scale, Maddox wing apparatus, the critical flicker fusion threshold test, blood pressure and heart rate measurements, serum and CSF cortisol and plasma ADH measurements, as well as CSF drug level determinations. Clinically, temazepam 20 mg proved to be comparable with flunitrazepam I mg, although the latter more effectively prevented cardiovascular changes and pre-operative hormonal stress reaction. No correlation was found between the CSF drug level (bioassayed by radioreceptor assay) and the clinical response of the two benzodiazepines, nor was there any correlation between the cortisol or ADH levels versus the CSF drug levels. On the whole, flunitrazepam proved to be marginally better than temazepam as an oral premedicant.

Reduced lactate washout from the myocardium after combining St. Thomas I type cardioplegia with topical cooling of the heart. Myocardial oxygenation and performance after cardioplegia in coronary artery bypass grafting patients.

The myocardial oxygen extraction was diminished with a resulting coronary sinus blood oxygen saturation of 48 +/- 5 (SEM) %, as compared to the pre-bypass control level of 30 +/- 1%, two minutes after the ischaemic period in St. Thomas I type cardioplegia (CPL) with topical cooling of the heart during a coronary bypass operation. The myocardial oxygen extraction returned to prebypass levels after ten minutes of reperfusion following ischaemia and remained so after the bypass. The postischaemic myocardial lactate washout of the CPL-patients was compared to that of another group of coronary surgical patients, in whom intermittent ischaemia and topical cooling (IITC) were used for myocardial protection. It was found that the lactate washout two minutes after the single ischaemic period in the CPL-patients was far less than the lactate washout two minutes after each ischaemic period in the IITC-group. The greatest arterial-coronary sinus lactate difference in the IITC-group was -1.7 +/- 0.2 mmol/l and in the CPL-group -0.7 +/- 0.2 mmol/l. Cardiac performance (assessed by the CI-PCWP relationship) which was moderately depressed by the anaesthesia and surgery before bypass, returned gradually to the control level within 20 hours after operation. The present study shows that no apparent postischaemic abnormality in myocardial oxygen utilization develops when single dose cardioplegia, together with topical cooling of the heart, is used for myocardial protection, and that the accumulation of myocardial lactate during ischaemia is less during cardioplegia with topical cooling of the heart than during intermittent ischaemic with topical cooling for coronary artery bypass grafting operations.

Effect of different respirator adjustments on central haemodynamics in open-heart surgery patients.

Changes in cardiac index (CI) mean pulmonary artery pressure (PAP), mean pulmonary capillary wedge pressure (PCWP), central venous pressure (CVP), and pulmonary artery vascular resistance (PVR), associated with spontaneous respiration (SR) and two different types of intermittent positive pressure ventilation (IPPPV and IPNPV) were studied in a total of 17 patients undergoing aortic valve replacement or myocardial revascularization. Swan-Ganz thermodilution pulmonary artery cardiac output catheters were used and the aim was to determine: whether postoperative cardiac output may paradoxically be greater during IPPPV than during IPNPV or SR; whether the use of "negative" pressure in the expiratory phase during controlled ventilation may be responsible for bringing about the central haemodynamic conditions prevailing during spontaneous respiration; and whether, in weaning from postoperative IPPPV to SR, there is a risk of pulmonary congestion as a consequence of possible autotransfusion. IPPPV connected with anaesthesia induction caused a highly significant deterioration central haemodynamics. The use of positive end-expiratory pressure (PEEP) is not to be recommended for such patients at this stage. On the first postoperative day, the mean CI was lower during IPPPV than during IPNPV (P less than 0.1) or during SR (P less than 0.05). The changes observed in CI, were, however, so slight that the authors consider the routine use of PEEP to be beneficial during controlled ventilation following major open-heart surgery. In some patients, the CI was paradoxically higher during IPPPV than during IPNPV or SR. The mean CI was nearly the same during IPNPV (3.32) as during SR (3.38). However, PAP, PCWP and PVR values were significantly higher during SR than during IPNPV. Thus, according to this study, the use of "negative" end-expiratory pressure during controlled ventilation did not in these patients produce central pressure conditions corresponding to spontaneous respiration. The present study supports the finding that in weaning from controlled ventilation with PEEP to SR there is a danger of pulmonary congestion. This could be predicted by measurement of pulmonary wedge pressure, but not by measurement of central venous pressure.