Stefan Lehtipalo

Pleasant human touch is represented in pregenual anterior cingulate cortex

Touch massage (TM) is a form of pleasant touch stimulation used as treatment in clinical settings and found to improve well-being and decrease anxiety, stress, and pain. Emotional responses reported during and after TM have been studied, but the underlying mechanisms are still largely unexplored. In this study, we used functional magnetic resonance (fMRI) to test the hypothesis that the combination of human touch (i.e. skin-to-skin contact) with movement is eliciting a specific response in brain areas coding for pleasant sensations. The design included four different touch conditions; human touch with or without movement and rubber glove with or without movement. Force (2.5 N) and velocity (1.5 cm/s) were held constant across conditions. The pleasantness of the four different touch stimulations was rated on a visual analog scale (VAS-scale) and human touch was rated as most pleasant, particularly in combination with movement. The fMRI results revealed that TM stimulation most strongly activated the pregenual anterior cingulate cortex (pgACC). These results are consistent with findings showing pgACC activation during various rewarding pleasant stimulations. This area is also known to be activated by both opioid analgesia and placebo. Together with these prior results, our finding furthers the understanding of the basis for positive TM treatment effects.

Continuous interscalene brachial plexus block for postoperative analgesia following shoulder surgery

Background: Severe postoperative pain is a well‐known problem following shoulder surgery. This study evaluates the clinical efficacy of continuous interscalene brachial plexus block, patient‐controlled analgesia, and morphine (i.v. and i.m.) for postoperative analgesia in this setting.

Physiological responses to touch massage in healthy volunteers.

OBJECTIVES To evaluate effects of touch massage (TM) on stress responses in healthy volunteers. METHODS A crossover design including twenty-two (mean age=28.2) healthy volunteers (11 male and 11 female) cardiac autonomic tone was measured by heart rate (HR) and heart rate variability (HRV). Stress hormone levels (cortisol) were followed in saliva. We also measured blood glucose and serum insulin. Extracellular (ECV) levels of glucose, lactate, pyruvate and glycerol were followed using the microdialysis technique (MD). TM was performed on hands and feet for 80 min, during control, participants rested in the same setting. Data were collected before, during, and after TM and at rest. Saliva cortisol, serum glucose, and serum insulin were collected before, immediately following, and 1 h after intervention or control, respectively. RESULTS After 5 min TM, HR decreased significantly, indicating a reduced stress response. Total HRV and all HRV components decreased during intervention. Saliva cortisol and insulin levels decreased significantly after intervention, while serum glucose levels remained stable. A similar, though less prominent, pattern was seen during the control situation. Only minor changes were observed in ECV levels of glucose (a decrease) and lactate (an increase). No significant alterations were observed in glycerol or pyruvate levels throughout the study. There were no significant differences between groups in ECV concentrations of analyzed substances. CONCLUSIONS In healthy volunteers, TM decreased sympathetic nervous activity, leading to decreased overall autonomic activity where parasympathetic nervous activity also decreased, thereby maintaining the autonomic balance.

Cutaneous sympathetic vasoconstrictor reflexes for the evaluation of interscalene brachial plexus block

Background: Although signs of sympathetic blockade following interscalene brachial plexus block include Horner’s syndrome, increased skin temperature and vasodilatation, the degree of sympathetic blockade is not easily determined. The aim of this study was, therefore, to use activation of cutaneous finger pad vasoconstrictor reflexes for description and quantification of the degree of sympathetic blockade following unilateral interscalene brachial plexus block.

Negative mesenteric effects of lung recruitment maneuvers in oleic acid lung injury are transient and short lasting.

Objective: To test the hypothesis that repeated recruitment maneuvers (RMs) have sustained negative effects on mesenteric circulation, metabolism, and oxygenation 60 mins after RMs in pigs with oleic acid lung injury. Further, we aimed to test the hypothesis that an infusion of prostacyclin (PC) at 33 ng·kg−1·min−1 would attenuate such possible negative mesenteric effects. Design: Randomized, experimental, controlled study. Setting: University hospital animal laboratory. Subjects: A total of 31 anesthetized, fluid‐resuscitated pigs with oleic acid lung injury. Interventions: Animals were randomized to one of the following four groups: a control group (n = 7) that received no intervention, recruitment group (n = 8) that underwent the RM sequence, a prostacyclin group (n = 8) that received an infusion of PC, and a recruitment‐prostacyclin group (n = 8) that received an infusion of PC and concomitant RM sequence. Measurements and Main Results: We measured systemic and mesenteric hemodynamic variables, jejunal mucosal perfusion, mesenteric lactate flux, jejunal tissue oxygen tension, and mesenteric oxygen delivery, uptake, and extraction ratio. Five minutes after RMs, mesenteric oxygen extraction ratio and mesenteric lactate flux were more prominently increased in the recruitment group, giving evidence of worsened mesenteric conditions after RMs. These signs of worsened conditions were further supported by more decreased jejunal tissue oxygen tension and portal vein oxygen saturation in the recruitment group. PC preserved mesenteric oxygenation, as indicated by less of a decrease in portal vein oxygen saturation at the time corresponding to 5 mins after RM and less of a decrease in mesenteric oxygen delivery at the time corresponding to 15 mins after RM. PC preserved mesenteric oxygenation as indicated by less of a decrease in portal vein oxygen saturation at 5 mins after RM and an attenuated increase in mesenteric oxygen extraction ratio at 5 mins after RM. There was a trend toward worsened jejunal mucosal perfusion, although not significant. Conclusions: In an oleic acid lung injury model, three repeated RMs did not improve systemic oxygenation or lung mechanics. Negative effects on mesenteric oxygenation and metabolism were transient and short lasting. The intestinal effects of PC during RMs were minor and opposing, showing preserved oxygenation but a trend toward worsened mucosal perfusion.

Local metabolic effects of dopexamine on the intestine during mesenteric hypoperfusion

This self-controlled experimental study was designed to test the hypothesis that dopexamine, a synthetic catecholamine that activates dopaminergic (DA-1) and &bgr;2-adrenergic receptors, improves oxygenation in the jejunal mucosa during intestinal hypotension. In six normoventilated barbiturate-anesthetized pigs, controlled reductions in superior mesenteric arterial pressure (PSMA) was obtained by an adjustable clamp around the artery. Dopexamine infusions (0.5 and 1.0 &mgr;g · kg−1 · min−1) were administered at a freely variable PSMA (i.e., with the perivascular clamp fully open) and at a PSMA of 50 mmHg and 30 mmHg. We continuously measured superior mesenteric venous blood flow (QMES; transit-time ultrasonic flowmetry), jejunal mucosal perfusion (laser Doppler flowmetry), and tissue oxygen tension (Po2 TISSUE; microoximetry). Jejunal luminal microdialysate of lactate, pyruvate, and glucose were measured every 5 min. Measurements of mucosal Pco2 (air tonometry), together with blood sampling and end-tidal Pco2 measurements, enabled calculations of pHi and Pco2 gap. Dopexamine reduced mesenteric vascular resistance and increased QMES at a PSMA of 50 mmHg and 30 mmHg. At a PSMA of 30 mmHg, dopexamine increased mesenteric oxygen delivery but did not influence mesenteric oxygen uptake or extraction. In this situation, dopexamine had no beneficial effect on jejunal mucosal blood flow. On the contrary, dopexamine increased mesenteric net lactate production and Pco2 gap, whereas Po2 TISSUE and pHi decreased. Jejunal luminal microdialysate data demonstrated an increased lactate concentration and a pattern of decreased glucose concentration and increased luminal lactate-pyruvate ratio. These negative metabolic effects of dopexamine should be taken into account in situations of low perfusion pressures.

Effects of positive end-expiratory pressure on intestinal circulation during graded mesenteric artery occlusion.

Background: Reduced gut perfusion is associated with multiple organ failure. Positive end‐expiratory pressure (PEEP) reduces cardiac output (CO) and portal blood flow, and might be detrimental in a situation of already compromised intestinal circulation. The aim of this study was to investigate regional circulatory and metabolic effects of PEEP during graded regional hypoperfusion.

Intestinal circulation, oxygenation and metabolism is not affected by oleic acid lung injury.

This study was performed to establish a platform for further studies on effects of ventilatory treatment modalities on the intestines during mechanical ventilation of acute lung injury (ALI). We tested the hypotheses that oleic acid (OA) infusion causes changes in intestinal circulation, oxygenation and metabolism, and that OA is distributed to tissues outside the lung. This was performed as an experimental, prospective and controlled study in an university animal research laboratory. Thirteen juvenile anaesthetized pigs were used in the main study, where seven were given an intravenous infusion of 0·1 ml kg−1 OA and six served as control (surgery only). In a separate study, four animals were given an intravenous infusion of 0·1 ml kg−13H‐labelled OA. We measured systemic and mesenteric (portal venous blood flow, jejunal mucosal perfusion) haemodynamic parameters, mesenteric oxygenation (jejunal tissue oxygen tension) and systemic cytokines (tumour necrosis factor‐α and interleukin‐6). We calculated mesenteric lactate flux and mesenteric oxygen delivery, uptake and extraction ratio. In the animals given 3H‐OA, we measured 3H‐OA in different tissues (lungs, heart, liver, kidney, stomach, jejunum, colon and arterial blood). We found that OA given intravenously is distributed in small amounts to the intestines. This intestinal exposure to OA does not cause intestinal injury when evaluating mesenteric blood flow, metabolism or oxygenation. OA infusion induced a moderate increase in mean pulmonary arterial pressure and a decrease in PaO2/Fraction inspired O2 (P/F) ratio, giving evidence of severe lung injury. Consequently, the OA lung injury model is suitable for studies on intestinal effects of ventilatory treatment modalities during mechanical ventilation of ALI.

Splanchnic vasoconstriction by angiotensin II is arterial pressure dependent

Background: Our hypothesis was that splanchnic vasoconstriction by exogenous angiotensin II (Ang II) is significantly potentiated by local mechanisms increasing vasomotor tone and that splanchnic tissue oxygenation during administration of Ang II is perfusion pressure dependent. The aim was to study local splanchnic circulatory effects and tissue oxygenation during intravenous infusion of Ang II at different levels of regional arterial driving pressure in a whole‐body large animal model.

Does dopexamine influence regional vascular tone and oxygenation during intestinal hypotension

Background: Local effects of dopexamine on intestinal vascular tone and oxygenation were investigated during intestinal hypotension. To this end, we employed an experimental model, in which the superior mesenteric arterial pressure (PSMA) was controlled by an adjustable perivascular clamp. This approach enabled us to keep the intestinal perfusion pressure (IPP) constant in the face of any systemic circulatory alterations.