Gunnar Ström

CIRCULATORY EFFECTS OF SUCCINYLCHOLINE IN MAN

1 The effects of intravenous (standard apnoeic) and intra‐arterial doses of succinylcholinc chloride (SCh) on peripheral circulation (forearm, hand, skeletal musculature, skin, mucosa of the sigmoid colon), arterial blood pressure and heart rate were studied in 15 unanaesthetized and 17 anaesthetized subjects. 2 Standard apnoeic doses of SCh injected intravenously in anaesthetized subjects produced circulatory changes usually of a biphasic character, a sudden initial decrease in peripheral blood flow and heart rate followed by an increase throughout The apnoeic period; there was also a rise in arterial blood pressure. The initial decrease occurred synchronously with the preparalytic activity of the skeletal musculature (twitchings), but unlike the latter also after repeated injections of SCh. The magnitude of the initial decrease was, on an average, 16 per cent for the peripheral circulation, and 7 per cent for heart rate. The subsequent average increase amounted to 16 per cent above the initial control value for the peripheral circulation, 8 per cent (5 mm Hg) for the systolic, 21 per cent (6 mm Hg) for the diastolic and 9 per cent (4 mm Hg) for the mean arterial blood pressures. 3 Doses of SCh which caused local muscular relaxation on continuous infusion into the brachial artery of unanaesthetized subjects also caused an average blood flow increase in forearm and hand of 43 per cent. This blood flow response remained only during the first few minutes, and then gradually decreased to the control level during the course of the next 10–15 minutes. 4 After the second or third repeated intravenous injection of SCh, but not after further injections, a sudden and marked bradycardia sometimes occurred, with a duration of up to 3 minutes. 5 With repeated intravenous injections of SCh in a standard apnoeic dose, the size and duration of both the circulatory reactions and the duration of the apnoeic period gradually decreased (‘tachyphylaxis’). 6 The individual sensitivity to SCh was rather variable. This was particularly evident in patients with a labile and hyperkinetic circulation (‘vasoregulatory asthenia’) in whom the average blood flow increase during continuous intra‐arterial infusion of SCh was considerably higher than in the control group. 7 The circulatory changes after an intravenous injection of an apnoeic SCh dose should be evaluated in relation to the various interfering factors, such as anaesthesia, atropine premedication, endotracheal intubation, positive‐pressure ventilation, hypoxia, hypercapnia, hypothermia during anaesthesia, and acidosis. 8 The possible mechanisms by which SCh exerts its circulatory effects are discussed, especially the direct effects on the vessels and heart and the indirect effects via nervous or humoral mediators. It is concluded that SCh seems to be a general vasodilator substance. A review of the literature shows that the vasodilator effect of SCh also exists in circulatory areas of the body not directly studied in the present investigation. The vasodilatation is partially caused by a local action of SCh on the peripheral circulation, as demonstrated by the effect of intra‐arterial infusion. It is suggested as a possible explanation that SCh may cause initial stimulation (contraction) and subsequent relaxation not only of skeletal, but also of smooth muscle, especially in blood vessels. 9 It is concluded that the circulatory effects of SCh are of clinical significance.

Chronic Supraventricular Tachycardia of Continuous or Repetitive Type in Children A Note on Circulatory Function and Long‐Term Prognosis

Chronic supraventricular tachycardia is an unusual disturbance which may occur also in children. I n such cases, signs of gross congenital malformation or acquired disease of the heart are usually absent, and the condition may be so stable over a period of many years that a local malformation of the impulse-forming atrial or nodal system has been suggested as its cause (Parkinson & Papp (7)) . The tachycardia may be either of a “continuous” and “constant” type or of a “repetitive” and “paroxysmal” type, and i t is clearly distinguished from the classical paroxysmal atrial tachycardia. The circulatory functional effect of the supraventricular tachycardia appears to depend partly on the degree of atrioventricular (AV) conduction block, i.e. on the resulting ventricular rate, and partly on the effectiveness of ventricular contraction at these high rates. In the majority of pediatric cases, no serious incapacitation is produced or there may even be no subjective symptoms a t all. The long-term prognosis is judged to be good, at least in children, in whom spontaneous remission often occurs in adolescence (see Parkinson

Circulatory and psychophysiological reactions to adrenaline and noradrenaline in patients with vasoregulatory asthenia

Summary1.The effects of intravenous and intra-arterial infusion of adrenaline and noradrenaline on the blood flow in the forearm and hand, heart rate, arterial blood pressure, lactate concentration in blood effluent from a deep (muscle) forearm vein, and on the incidence of subjective symptoms were studied in 14 patients with vasoregulatory asthenia (VA) and 9 clinically healthy control subjects (CS).2.In the VA group the highest intravenously administered catecholamine dose which was tolerated by the average individual person with regard to subjective symptoms, was about 40 per cent lower for adrenaline (10 Μg/min), and between 15 and 65 per cent higher for noradrenaline (29 Μg/min) than that tolerated by the CS subjects. The number of various subjective symptoms which arose on intravenous infusion of catecholamines was twice as high for adrenaline, but less for noradrenaline, in the VA group than in the control subjects. Ten of the VA patients noted their usual typical and personally patterned symptoms on intravenous infusion of adrenaline.3.The circulatory effects of intravenously or intra-arterially administered adrenaline were at comparable dose rates in some respects different in VA and CS but the differences were not pronounced. With comparable doses of noradrenaline, however, a pronounced difference was found, the increase in arterial blood pressure and the decrease in forearm and hand blood flow (especially on intra-arterial infusion) being less marked in the VA group. Ectopic heart beats occurred less frequently in VA than in CS during these infusions.4.Infusions of adrenaline at 0.01 and 0.1 Μg/min into the brachial artery caused a gradual slight increase in the lactate concentration of blood effluent from the local forearm musculature, which on the average was of a similar magnitude (about 4 mg/100 ml) in the VA and CS groups.5.It is concluded that the circulatory sensitivity of the VA patients to noradrenaline was decreased. The sensitivity to intravenous adrenaline was increased in VA with respect to subjective symptomatology. The cause and nature of the altered catecholamine sensitivity are not known.

Circulatory reactions in the forearm and hand during and after exercise in patients with vasoregulatory asthenia

Summary1.Investigations were made on 15 patients with vasoregulatory asthenia (VA) and 14 clinically healthy control subjects (CS) concerning the magnitude and variations of the circulation in the resting forearm and hand during supine leg exercise, and in the forearm after exhaustive forearm exercise. Measurements were performed of blood flows in forearm and hand (venous occlusion plethysmography), arterial blood pressure, heart rate, a-v O2 difference between the brachial artery and a deep forearm vein, and blood lactate concentration, and calculations were made of O2 uptake in deep forearm (musculature) and vascular resistances in forearm and hand.2.The blood flowat rest and duringleg exercise was in VA on the average two to three times higher in the forearm, and significantly lower in the hand, than in CS. The difference was especially pronounced in those patients who showed a marked reduction of physical work capacity (W170). The lactate concentration in arterial blood increased more in VA during leg exercise with loads of up to 400–600 kpm/min than in CS, when related to absolute work load (kpm/min), but less in VA when related to relative work load (heart rate).Both at rest and during leg exercise, the a-v O2 difference between brachial artery and a deep forearm vein was considerably lower in VA than in CS, while the calculated O2 uptake in deep forearm (muscle) was similar in both groups.Especially in VA, the blood flow increase during leg exercise was considerably higher in the forearm with blocked sympathetic vasoconstrictor tone than in the intact contralateral forearm. 3.The \lsmaximal\rs forearm blood flow, as measured immediately after exhaustive and in part ischemically performedforearm exercise, was on the average not significantly different in VA and CS. At the same time the calculated O2 uptake in deep forearm (muscle) in VA was only half that in CS; and the lactic acid concentration of blood from a deep forearm vein was slightly lower in VA than in CS. The post-exercise return of the changed circulatory valces to the control levels was not retarded in VA and even occurred slightly faster than in CS. 4.The results are interpreted as indicating an abnormal blood flow distribution during exercise in VA, with a larger than normal part of the cardiac output flowing through resting muscles, and a smaller than normal part flowing through the active muscles. The results are discussed with regard to the cause of hyperkinetic circulation in skeletal musculature and the reduction of physical work capacity in VA.ZusammenfassungIm Lungenparenchym: 1.Bei 15 Patienten mit vasoregulatorischer Asthenie (VA) und 14 klinisch gesunden Kontrollpersonen wurden die Kreislaufver\:anderungen in Unterarm und Hand w\:ahrend Beinarbeit im Liegen, sowie im Unterarm nach ersch\:opfender Arbeit der Unterarmmuskulatur untersucht. Gemessen wurden: die Durchblutung in Unterarm und Hand (Okklusionsplethysmographie), der arterielle Blutdruck, die Herzfrequenz, die a-vO2-Differenz zwischen A. brachialis und einer \lstiefen\rs Unterarmvene, und die Lactatkonzentration im Blut. Berechnet wurden: die O2-Aufnahme im \lstiefen\rs Unterarm (Skeletmuskulatur), und der Str\:omungswiderstand in Unterarm und Hand.2.Bei k\:orperlicher Ruhe und w\:ahrend Beinarbeit war die Unterarmdurchblutung der VA-Patienten im Durchschnitt 2\2-3mal h\:oher, ihre Handdurchblutung dagegen geringer als bei den Kontrollpersonen. Diese Unterschiede waren besonders deutlich bei Patienten mit st\:arkerer Verminderung des k\:orperlichen Arbeitsverm\:ogens W170. Bei VA stieg während Beinarbeit von 400–600 kpm/min die Lactatkonzentration im arteriellen Blut, wenn die Werte auf die absolute Arbeitsbelastung (kpm/min) bezogen wurden, stärker, wenn die Werte dagegen auf die relative Arbeitsbelastung (Herzfrequenz) bezogen wurden, geringer an als in der Kontrollgruppe.Die a-vO2-Differenz zwischen A. brachialis und einer ‘tiefen’ Unterarmvene war in Ruhe und während Beinarbeit bei VA geringer als bei den Kontrollpersonen. Die errechneto O2-Aufnahme im ‘tiefen’ Unterarm (Skeletmuskulatur) war dagegen ähnlich groß bei beiden Gruppen.Nach Blockade des lokalen sympathischen Vasokonstriktortonus im Unterarm nahm—besonders bei den VA-Patienten—der Anstieg der Unterarmdurchblutung während Beinarbeit erheblich zu. 3.Die unmittelbar nach Beendigung von ersch\:opfender, teilweise isch\:amisch ausgef\:uhrter Unterarmarbeit gemessene \lsmaximale\rs Unterarmdurchblutung war bei beiden Gruppen \:ahnlich gro\sB. Die O2-Aufnahme im \lstiefen\rs Unterarm (Skeletmuskulatur) betrug hier bei VA aber nur die H\:alfte des in der Kontrollgruppe gefundenen Wertes; auch die Lactatkonzentration in ven\:osem Blut aus der Unterarmmuskulatur war hier bei VA geringer als bei den Kontrollpersonen. Der R\:uckgang dieser Ver\:anderungen zu den Ausgangs-werten war bei VA nicht verz\:ogert.4.Die Ergebnisse k\:onnen f\:ur das Vorliegen einer abnormen Durchblutungsverteilung w\:ahrend k\:orperlicher Arbeit bei VA sprechen, n\:amlich in der Weise, da\sB hier ein gr\:o\sBerer Teil des Herzminutenvolumens als normalerweise durch die ruhende Skeletmuskulatur flie\sBt auf Kosten einer ausreichenden Durchblutung der arbeitenden Skeletmuskulatur selbst. M\:ogliche Ursachen der hyperkinetischen Skeletmuskeldurchblutung und der Verminderung des k\:orperlichen Arbeitsverm\:ogens bei VA werden diskutiert.1. Investigations were made on 15 patients with vasoregulatory asthenia (VA) and 14 clinically healthy control subjects (CS) concerning the magnitude and variations of the circulation in the resting forearm and hand during supine leg exercise, and in the forearm after exhaustive forearm exercise. Measurements were performed of blood flows in forearm and hand (venous occlusion plethysmography), arterial blood pressure, heart rate, a-v O2 difference between the brachial artery and a deep forearm vein, and blood lactate concentration, and calculations were made of O2 uptake in deep forearm (musculature) and vascular resistances in forearm and hand. 2. The blood flowat rest and duringleg exercise was in VA on the average two to three times higher in the forearm, and significantly lower in the hand, than in CS. The difference was especially pronounced in those patients who showed a marked reduction of physical work capacity (W170). Investigations were made on 15 patients with vasoregulatory asthenia (VA) and 14 clinically healthy control subjects (CS) concerning the magnitude and variations of the circulation in the resting forearm and hand during supine leg exercise, and in the forearm after exhaustive forearm exercise. Measurements were performed of blood flows in forearm and hand (venous occlusion plethysmography), arterial blood pressure, heart rate, a-v O2 difference between the brachial artery and a deep forearm vein, and blood lactate concentration, and calculations were made of O2 uptake in deep forearm (musculature) and vascular resistances in forearm and hand. The blood flowat rest and duringleg exercise was in VA on the average two to three times higher in the forearm, and significantly lower in the hand, than in CS. The difference was especially pronounced in those patients who showed a marked reduction of physical work capacity (W170). The lactate concentration in arterial blood increased more in VA during leg exercise with loads of up to 400–600 kpm/min than in CS, when related to absolute work load (kpm/min), but less in VA when related to relative work load (heart rate). Both at rest and during leg exercise, the a-v O2 difference between brachial artery and a deep forearm vein was considerably lower in VA than in CS, while the calculated O2 uptake in deep forearm (muscle) was similar in both groups. Especially in VA, the blood flow increase during leg exercise was considerably higher in the forearm with blocked sympathetic vasoconstrictor tone than in the intact contralateral forearm. 3. The \lsmaximal\rs forearm blood flow, as measured immediately after exhaustive and in part ischemically performedforearm exercise, was on the average not significantly different in VA and CS. At the same time the calculated O2 uptake in deep forearm (muscle) in VA was only half that in CS; and the lactic acid concentration of blood from a deep forearm vein was slightly lower in VA than in CS. The \lsmaximal\rs forearm blood flow, as measured immediately after exhaustive and in part ischemically performedforearm exercise, was on the average not significantly different in VA and CS. At the same time the calculated O2 uptake in deep forearm (muscle) in VA was only half that in CS; and the lactic acid concentration of blood from a deep forearm vein was slightly lower in VA than in CS. The post-exercise return of the changed circulatory valces to the control levels was not retarded in VA and even occurred slightly faster than in CS. 4. The results are interpreted as indicating an abnormal blood flow distribution during exercise in VA, with a larger than normal part of the cardiac output flowing through resting muscles, and a smaller than normal part flowing through the active muscles. The results are discussed with regard to the cause of hyperkinetic circulation in skeletal musculature and the reduction of physical work capacity in VA. The results are interpreted as indicating an abnormal blood flow distribution during exercise in VA, with a larger than normal part of the cardiac output flowing through resting muscles, and a smaller than normal part flowing through the active muscles. The results are discussed with regard to the cause of hyperkinetic circulation in skeletal musculature and the reduction of physical work capacity in VA. Im Lungenparenchym: 1. Bei 15 Patienten mit vasoregulatorischer Asthenie (VA) und 14 klinisch gesunden Kontrollpersonen wurden die Kreislaufver\:anderungen in Unterarm und Hand w\:ahrend Beinarbeit im Liegen, sowie im Unterarm nach ersch\:opfender Arbeit der Unterarmmuskulatur untersucht. Gemessen wurden: die Durchblutung in Unterarm und Hand (Okklusionsplethysmographie), der arterielle Blutdruck, die Herzfrequenz, die a-vO2-Differenz zwischen A. brachialis und einer \lstiefen\rs Unterarmvene, und die Lactatkonzentration im Blut. Berechnet wurden: die O2-Aufnahme im \lstiefen\rs Unterarm (Skeletmuskulatur), und der Str\:omungswiderstand in Unterarm und Hand. 2. Bei k\:orperlicher Ruhe und w\:ahrend Beinarbeit war die Unterarmdurchblutung der VA-Patienten im Durchschnitt 2\2-3mal h\:oher, ihre Handdurchblutung dagegen geringer als bei den Kontrollpersonen. Diese Unterschiede waren besonders deutlich bei Patienten mit st\:arkerer Verminderung des k\:orperlichen Arbeitsverm\:ogens W170. Bei 15 Patienten mit vasoregulatorischer Asthenie (VA) und 14 klinisch gesunden Kontrollpersonen wurden die Kreislaufver\:anderungen in Unterarm und Hand w\:ahrend Beinarbeit im Liegen, sowie im Unterarm nach ersch\:opfender Arbeit der Unterarmmuskulatur untersucht. Gemessen wurden: die Durchblutung in Unterarm und Hand (Okklusionsplethysmographie), der arterielle Blutdruck, die Herzfrequenz, die a-vO2-Differenz zwischen A. brachialis und einer \lstiefen\rs Unterarmvene, und die Lactatkonzentration im Blut. Berechnet wurden: die O2-Aufnahme im \lstiefen\rs Unterarm (Skeletmuskulatur), und der Str\:omungswiderstand in Unterarm und Hand. Bei k\:orperlicher Ruhe und w\:ahrend Beinarbeit war die Unterarmdurchblutung der VA-Patienten im Durchschnitt 2\2-3mal h\:oher, ihre Handdurchblutung dagegen geringer als bei den Kontrollpersonen. Diese Unterschiede waren besonders deutlich bei Patienten mit st\:arkerer Verminderung des k\:orperlichen Arbeitsverm\:ogens W170. Bei VA stieg während Beinarbeit von 400–600 kpm/min die Lactatkonzentration im arteriellen Blut, wenn die Werte auf die absolute Arbeitsbelastung (kpm/min) bezogen wurden, stärker, wenn die Werte dagegen auf die relative Arbeitsbelastung (Herzfrequenz) bezogen wurden, geringer an als in der Kontrollgruppe. Die a-vO2-Differenz zwischen A. brachialis und einer ‘tiefen’ Unterarmvene war in Ruhe und während Beinarbeit bei VA geringer als bei den Kontrollpersonen. Die errechneto O2-Aufnahme im ‘tiefen’ Unterarm (Skeletmuskulatur) war dagegen ähnlich groß bei beiden Gruppen. Nach Blockade des lokalen sympathischen Vasokonstriktortonus im Unterarm nahm—besonders bei den VA-Patienten—der Anstieg der Unterarmdurchblutung während Beinarbeit erheblich zu. 3. Die unmittelbar nach Beendigung von ersch\:opfender, teilweise isch\:amisch ausgef\:uhrter Unterarmarbeit gemessene \lsmaximale\rs Unterarmdurchblutung war bei beiden Gruppen \:ahnlich gro\sB. Die O2-Aufnahme im \lstiefen\rs Unterarm (Skeletmuskulatur) betrug hier bei VA aber nur die H\:alfte des in der Kontrollgruppe gefundenen Wertes; auch die Lactatkonzentration in ven\:osem Blut aus der Unterarmmuskulatur war hier bei VA geringer als bei den Kontrollpersonen. Der R\:uckgang dieser Ver\:anderungen zu den Ausgangs-werten war bei VA nicht verz\:ogert. 4. Die Ergebnisse k\:onnen f\:ur das Vorliegen einer abnormen Durchblutungsverteilung w\:ahrend k\:orperlicher Arbeit bei VA sprechen, n\:amlich in der Weise, da\sB hier ein gr\:o\sBerer Teil des Herzminutenvolumens als normalerweise durch die ruhende Skeletmuskulatur flie\sBt auf Kosten einer ausreichenden Durchblutung der arbeitenden Skeletmuskulatur selbst. M\:ogliche Ursachen der hyperkinetischen Skeletmuskeldurchblutung und der Verminderung des k\:orperlichen Arbeitsverm\:ogens bei VA werden diskutiert. Die unmittelbar nach Beendigung von ersch\:opfender, teilweise isch\:amisch ausgef\:uhrter Unterarmarbeit gemessene \lsmaximale\rs Unterarmdurchblutung war bei beiden Gruppen \:ahnlich gro\sB. Die O2-Aufnahme im \lstiefen\rs Unterarm (Skeletmuskulatur) betrug hier bei VA aber nur die H\:alfte des in der Kontrollgruppe gefundenen Wertes; auch die Lactatkonzentration in ven\:osem Blut aus der Unterarmmuskulatur war hier bei VA geringer als bei den Kontrollpersonen. Der R\:uckgang dieser Ver\:anderungen zu den Ausgangs-werten war bei VA nicht verz\:ogert. Die Ergebnisse k\:onnen f\:ur das Vorliegen einer abnormen Durchblutungsverteilung w\:ahrend k\:orperlicher Arbeit bei VA sprechen, n\:amlich in der Weise, da\sB hier ein gr\:o\sBerer Teil des Herzminutenvolumens als normalerweise durch die ruhende Skeletmuskulatur flie\sBt auf Kosten einer ausreichenden Durchblutung der arbeitenden Skeletmuskulatur selbst. M\:ogliche Ursachen der hyperkinetischen Skeletmuskeldurchblutung und der Verminderung des k\:orperlichen Arbeitsverm\:ogens bei VA werden diskutiert.