G. J. Scheffer

Effect of VIMA with sevoflurane versus TIVA with propofol or midazolam-sufentanil on the cytokine response during CABG surgery.

BACKGROUND AND OBJECTIVE Cardiac surgery with cardiopulmonary bypass triggers an inflammatory response involving pro-inflammatory cytokines such as tumour necrosis factor-alpha (TNF-alpha), interleukin 6 (IL-6) and interleukin 8 (IL-8). We investigated whether different anaesthetic techniques alter the pro-inflammatory cytokine response to cardiac surgery. METHODS Thirty patients scheduled for elective coronary artery bypass grafting (CABG) surgery were randomized into three groups of 10 patients. They received either volatile inhalation induction and maintenance (Group 1) or total intravenous anaesthesia with propofol and a minimal dose sufentanil (Group 2) or a moderate dose midazolam-sufentanil (Group 3). The effect of the different anaesthetic techniques on plasma levels of TNF-alpha, IL-6 and IL-8 were examined during and after anaesthesia. RESULTS Concentrations of TNF-alpha, and IL-8 were comparable in the three groups throughout all measurements. Before the start of cardiopulmonary bypass, IL-6 was significantly higher in Group 1 than in Group 2 (P = 0.009) or Group 3 (P = 0.030), but there were no differences between groups after cardiopulmonary bypass or postoperatively. In the three groups there was a positive correlation between aortic clamping time and serum concentrations of IL-6 (r = 0.54) and IL-8 (r = 0.62). Length of stay in intensive care was correlated with high levels of TNF-alpha (r = 0.78). CONCLUSIONS Albeit there is difference between the volatile induction and maintenance of the anaesthesia method and the total intravenous anaesthesia technique on the pro-inflammatory cytokine response to surgical stimulation before starting of cardiopulmonary bypass, neither technique can modify the pro-inflammatory cytokine response to ischaemia-reperfusion or extracorporeal circulation.

Effect of sevoflurane on the ex vivo secretion of TNF-α during and after coronary artery bypass surgery

Background and objective: Sevoflurane has been used for the induction and maintenance of anaesthesia during cardiac surgery owing to its favourable haemodynamic effects. It has been suggested that it offers protection against myocardial ischaemia‐reperfusion injury. Methods: We investigated the effect of sevoflurane on plasma concentrations of tumour necrosis factor‐&agr; (TNF‐&agr;) after ex vivo stimulation of whole‐blood leukocytes by lipopolysaccharide from 20 patients undergoing coronary artery bypass surgery. The patients were randomized to two groups. Group 1 patients were induced and maintained with sevoflurane; those in Group 2 were anaesthetized with moderate doses of midazolam‐sufentanil. Blood samples were drawn from the patients on seven occasions from before induction of anaesthesia until 24 h after skin closure. Results: Plasma concentrations of TNF‐&agr; were lower in Group 1 than in Group 2 after cessation of cardiopulmonary bypass (median (interquartiles): 25 (21‐30) versus 37 (28‐79) pg mL−1; P < 0.05) and 24 h after skin closure (196 (100‐355) versus 382 (233‐718) pgmL−1; P < 0.05). Postoperatively, two cases of myocardial infarction were recorded, one in each group. Six patients in Group 2 needed continued inotropic support after the first morning to maintain haemodynamic stability versus one patient in Group 1 (P < 0.05). The length of stay in the intensive care unit was significantly lower in Group 1 than in Group 2 (mean ± SD: 25 ± 16 versus 54 ± 30 h; P < 0.05). Conclusions: Sevoflurane reduces production of TNF‐&agr; more than total intravenous anaesthesia with midazolam‐sufentanil during cardiac surgery. This may reduce cardiac morbidity and the length of stay in the intensive care unit.

Alpha-1-Adrenoceptor Stimulation Induces Nitric Oxide Release in Rat Pulmonary Arteries

Adrenergic stimulation is often used to induce tone in clinical and intact animal studies and in isolated vessel segments. In some studies it has been found that a nitric oxide synthase (NOS) inhibitor or removal of the vascular endothelium augments the adrenergic-mediated vasoconstriction suggesting that endothelium-derived nitric oxide (NO) plays a role in adrenergic vasoconstriction [1, 2]. The aim of the present study was to investigate whether stimulation of ·1-adrenoceptors induces NO release in rat pulmonary arteries. We confirmed that inhibition of NOS in isolated pulmonary arteries results in an increased phenylephrine-mediated vasoconstriction. We also found that phenylephrine induces NO release in pulmonary vessels as detected with an NO sensor and that ·1-adrenoceptor blockade abolishes this NO release.

Thoracic sympathectomy: effects on hemodynamics and baroreflex control

Abstract Endoscopic thoracic sympathectomy at T2-T4 is an effective and safe treatment for primary axillary and palmar hyperhidrosis and facial blushing refractory to conventional treatment. T2 and T4 ganglia however are in the direct pathway of sympathetic innervation of the heart and part of the vasomotor nerves. In this study we investigate possible changes in steady-state hemodynamics as well as in beat-to-beat cardiovascular control after thoracoscopic sympathectomy of T2–T4.In 12 patients we measured continuously heart rate (HR) and blood pressure (BP) (non-invasively with Finapres™) during rest and during deep inspiration, in supine and sitting position as well as during a change from lying to standing. Stroke volume (SV) and total peripheral resistance (TPR) were estimated from the BP recordings by the Modelflow method. Markers for cardiovascular control were obtained from power and cross-spectra of BP and HR.After sympathectomy, only in the sitting position was mean HR decreased, while TPR and BP (diastolic and mean) were lower in the supine as well as sitting positions. SV clearly increased. Low frequency power in HR and BP was significantly decreased, just like the max/min ratio in HR after standing up, indicating a diminished capacity in sympathetic vasomotor control. High frequency power of HR as well as baroreflex sensitivity, both parasympathetic markers, did not change in a statistically significant manner.Conclusion: Besides altering steady-state hemodynamics, a thoracic sympathectomy causes relatively small, though measurable changes in cardiovascular control, in particular of peripheral vasomotion.

The differential effect of propofol on contractility of isolated myocardial trabeculae of rat and guinea‐pig

The effects of propofol on myocardial contractility were studied in rat, in which the contractile activation mainly depends on calcium derived from the sarcoplasmic reticulum (SR), and guinea‐pig, in which transsarcolemmal influx of calcium plays a major role. Intact and chemically skinned trabeculae from the right ventricle were studied. Intact trabeculae were electrically stimulated and force development during steady state and post rest contractions was measured. In saponin skinned trabeculae Ca2+ uptake and release by the SR was studied. In Triton skinned trabeculae the influence of propofol on calcium sensitivity of the myofilaments was studied. In intact rat trabeculae propofol in concentrations of 28, 112 and 280 μM did not change peak force development nor the pattern of post rest contraction. In guinea‐pig trabeculae propofol significantly reduced peak force to respectively 64, 40 and 23% of control values and the post rest contractions were potentiated. In skinned trabeculae propofol did not affect Ca2+ handling by the SR, nor did it change force production and Ca2+ sensitivity of the myofilaments. This study shows that, in contrast to rat, in guinea‐pig propofol directly depresses myocardial contractility, probably by decreasing transsarcolemmal Ca2+ influx. There is no significant influence of propofol on Ca2+ handling by the SR, nor on the contractile proteins.

The validity and reproducibility of the skin vasomotor test—studies in normal subjects, after spinal anaesthesia, and in diabetes mellitus

Skin sympathetic vasomotor control can be examined in the extremities by the skin vasomotor test. In this test the change in skin blood flow and skin temperature in the hand and foot in response to a cold stimulus is utilized as an index of distal sympathetic nerve fibre integrity. This is of importance in conditions such as diabetes mellitus as peripheral autonomic neuropathy is associated with orthostatic hypotension and diabetic foot complications. The validity and reproducibility of the test as a marker of distal sympathetic nerve function has been studied. The test was performed in nine healthy control subjects and in nine subjects (undergoing minor surgery) after a sympathetic nerve conduction block (L2–L3) was achieved in the lower extremities by spinal analgesia. Changes in skin temperature (p < 0.001) and skin blood flow (p < 0.005) in responses to cooling were significantly larger in the control group than in the group with spinal analgesia. Repeated skin temperature measurements on 42 occasions (test—retest period of 4 weeks) in eight healthy and 34 diabetic subjects indicated a reliability coefficient of 80%. We conclude, therefore, that the skin vasomotor test provides a valid and reproducible quantitative assessment of skin sympathetic nerve function in upper and lower extremities.

THE DIFFERENTIAL EFFECT OF PROPOFOL ON CONTRACTILITY OF ISOLATED MYOCARDIAL TRABECULAE OF RAT AND GUINEA PIG

1. The effects of propofol on myocardial contractility were studied in rat, in which the contractile activation mainly depends on calcium derived from the sarcoplasmic reticulum (SR), and guinea-pig, in which transsarcolemmal influx of calcium plays a major role. 2. Intact and chemically skinned trabeculae from the right ventricle were studied. Intact trabeculae were electrically stimulated and force development during steady state and post rest contractions was measured. In saponin skinned trabeculae Ca(2+) uptake and release by the SR was studied. In Triton skinned trabeculae the influence of propofol on calcium sensitivity of the myofilaments was studied. 3. In intact rat trabeculae propofol in concentrations of 28, 112 and 280 microM did not change peak force development nor the pattern of post rest contraction. In guinea-pig trabeculae propofol significantly reduced peak force to respectively 64, 40 and 23% of control values and the post rest contractions were potentiated. In skinned trabeculae propofol did not affect Ca(2+) handling by the SR, nor did it change force production and Ca(2+) sensitivity of the myofilaments. 4. This study shows that, in contrast to rat, in guinea-pig propofol directly depresses myocardial contractility, probably by decreasing transsarcolemmal Ca(2+) influx. There is no significant influence of propofol on Ca(2+) handling by the SR, nor on the contractile proteins.

Noninvasive Continuous Blood Pressure Measurement with the Cortronic APM 770

Methods for noninvasive and continuous measurement of the arterial bloodpressure combine the advantages of minimal risks for the patient and ease of use. If these methods are reliable and accurate they can in many occasions replace invasive bloodpressure measurements, thus avoiding the possible complications inherent to the invasive technique (1).

Monitor; a Low Cost, Versatile Data Acquisition Program

For research purposes it is often necessary to collect analog data. Until recently it was customary to view this analog data on an oscilloscope, and to store it on an analog tape recorder, thus introducing with the disadvantage of extra noise and a limited dynamic range. Interesting parts of the data could be played back for reviewing and production of a hard copy with a chart recorder. After this the tedious job of working out the collected data started. Time intervals and amplitudes were measured with a ruler and recorded manually on an other piece of paper. From this data graphs were plotted manually and statistics were calculated.

CONTINUOUS PULSE CONTOUR CARDIAC OUTPUT DURING MAJOR ABDOMINAL VASCULAR SURGERY

A new pulse contour method to determine cardiac output continuously in patients on a beat-to-beat basis from an arterial pressure wave has been implemented in a simple, fully automatic computer system. The pulse contour method computes a volume from the systolic area under the arterial pressure curve. This calculation requires a model which relates volume and pressure. The Wesseling method used in our study is based on a transmission line model of the aorta1.