In pulmonary operations, the correction of circulatory disorders is indicated both in cases when hemodynamic changes do not correspond to the increased energy, plastic and oxygen needs of the body (hypodynamic type of blood circulation), and in situations where the delivery of necessary substances to the tissues is provided at maximum voltage of compensatory processes.
The desire to determine and maintain the optimal type of blood circulation reaction is due to the fact that it affects the clinical results of treatment, the frequency of postoperative complications, mortality. As our studies have shown, the postoperative period is most favorable if even during the first day it is possible to achieve a stable stabilization of the shock index of more than 40 ml / m 2 and a cardiac index of more than 3.5 l / min * m 2. In this group of patients, the frequency of postoperative complications was 7.4%, and in patients with circulatory hypodynamia, it was 48.4%. We regard the moderate hyperdynamic type of blood circulation as a “sufficient and adequate” reaction, considering it to be a consequence of the patient’s good compensatory reserves and an indicator of its effective anesthetic protection. Cardiotropic therapy is not required for the vast majority of patients in this group.
A different situation arises if an increase in the minute volume of blood circulation is provided by excessive tachycardia or centralized blood flow. An increase in the cardiac index under these conditions of more than 3.5 l / min * m2 with a shock index less than 35 ml / m 2 indicates a “sufficient but not adequate” reaction of the circulatory system with a high risk of disruption of compensatory processes. In this case, intensive therapy should be aimed primarily at eliminating the causes of this condition and include effective blockade of pain, autonomic and mental stimulation (conduction anesthesia, central analgesia,
intramuscular injections of 2 ml of a 0.25% solution of droperidol, 0.5— ml of a 5% solution of pentamine, 0.5-1 ml of a 2% solution of benzogeksoniya, etc.), treatment of gas exchange disorders, correction of anemia and hypovolemia.
On the 1 st day after the operation, hypovolemia is the main cause of the hypodynamic blood circulation. It occurs not only as a result of unrepaired blood loss or exudation. Pain, systemic hypotonia, microcirculation disorders, endogenous intoxication, anorexia and many other causes significantly alter the water-electrolyte balance in the patient’s body, promote redistribution of fluid from the vascular and cellular sector into the extracellular space, lead to intravascular blood cell loss, changes in its composition, increase oxygen debt and, ultimately, to the development of energodynamic circulatory insufficiency, closing the vicious circle (Shanin Yu.N., 1978; Kostyuchenko LA, 1988). To prevent these violations in the first hours after the operation, even with full, ahead,replenishment of blood loss, it is advisable to continue the intravenous infusion of polyionic (mainly glucose-potassium) and rheologically active solutions, plasma. The volume of infusion is determined by the type of resection, the need for parenteral nutrition, the rate of exudation and the nature of the discharge from the drainage and averages 30 ml / kg of the patient’s body weight on the 1st day.
Stabilization of the BCC and, accordingly, earlier enteral administration of fluidity contributes to an earlier cessation of intravenous fluids. Given that in the coming hours after the operation, the possibility of self-drinking is limited in volume, you can use the infusion of fluid through a thin, with an internal diameter of 1– mm nasogastrointestinal probe, installed 12 hours before the operation. Immediately before the start of surgery, the position of the probe is monitored radiologically and, if its end is behind the ligament of Treitz, we begin already during the operation a slow drip of monomeric mixtures (5% glucose solution, mineral water, polyamine) in total volume up to 30 ml / kg per day. As shown by studies conducted in our clinic, enteral infusions are not accompanied by objective and subjective disorders and can reduce the amount of intravenous fluids and, consequently, the load on the lung tissue by 1.5 times. Especially justified is the use of this method of correction of the BCC, and then the power for combined pulmonary esophageal resections.
We emphasize that a rational infusion program not only prevents hypovolemia, but also allows to reduce the volume of blood transfusions, to eliminate excessive transfusions of red blood cells containing media, which in turn improves the results of treatment. The feasibility of maintaining a diluted and controlled by the indicators of the oxygen balance of blood dilution confirm our data on the positive effect of hemodilution on the state of vital systems and the frequency of complications after lung operations. Note that all studies were performed by comparing the results of treatment of comparable groups of patients with the same amount of blood loss, while the degree of hemodilution after surgery directly depended on the volume of the transfused donor erythrocyte-containing media.
The hemodilution prolonged in 1 —– and the day after the operation with hematocrit of 0.25–0.27 l / l and 0.28–, 32 l / l was well tolerated by the majority of patients, and the frequency of complications in these groups was 1.5–1 times less than in groups with hematocrit of 0.33–, 37l / l and more than 0.38l / l. This effect of hemodilution on the postoperative period is due to the fact that it creates more favorable conditions in the body for maintaining the dynamic balance of the mechanisms
oxygen supply than the hemoglobin or hematocrit values achieved by blood transfusion, which are close to “normal”. At the same time, the load on the various components of the oxygen transport system depends on the degree of hemodilution, with increasing of which, within the limits studied, the achievement of useful the adaptive result of the “compliance of oxygen delivery to tissue needs” is ensured by an increase in the “productivity” of blood circulation. As a result, the ratio of the role of the various components of the oxygen transport system corresponds to their functional reserves. Protecting the pulmonary stage of gas exchange from relative overstrain, hemodilution reduces the risk of developing clinically significant respiratory disorders. Ensuring transport and oxygen consumption in conditions of reduced oxygen capacity of the blood due to hemodilution occurs due to an increase in the volumetric blood flow velocity, which is increased to a greater extent by increasing the heart’s stroke volume and improved regional perfusion. This hemodynamic mode is the most economical, efficient and corresponds to the postoperative energy,information and metabolic needs of the body. As a result, oxygen transport does not fall below 350 ml / min * m2, that is, the homeostasis-providing level. The results obtained allow us to reasonably apply hemodilution controlled in terms of oxygen balance in the early postoperative period and in patients with concomitant diseases of the circulatory system.
We emphasize that a prerequisite for the safe use of hemodilution is constant dynamic monitoring of indicators of transport and oxygen consumption, which allows not only more accurately determine indications for blood transfusion, but also assess the state of the oxygen transport system as a whole, timely identify its weakest link and change the program accordingly intensive care.
Replacement pathogenetic infusion-transfusion therapy of circulatory hypodynamia is necessarily combined in the postoperative period with pharmacological correction of cardiac output. If myocardial functional reserves are limited, then cardiac glycosides are prescribed (0.5-1 ml of a 0.05% solution of strophanthin, 0.5-1 ml of a 0.06% solution of corglycone intravenously slowly 2 times a day). It is only necessary to remember that the use of these drugs is contraindicated in bradycardia, atrioventricular blockade, and unstable angina and dangerous (due to increased toxicity) in conditions of severe hypoxia .
In addition to cardiac glycosides, phosphodiesterase inhibitors (amrinone, enoximone, pyroximone, etc.) have a positive inotropic effect, which not only increase the strength of heart contractions, but also reduce the tone of peripheral vessels. As a result, the pre- and afterload of the heart is reduced, and the volumetric blood flow rate increases without increasing the myocardial oxygen consumption. In moderate doses or in combination with adrenergic mimetics, these drugs can be used even in patients with decompensated myocardiopathy, as well as in severe heart failure, in the case of refractoriness to cardiac glycosides and diuretics (J.-L.Vincent, 1993). The initial dose of amrinone for intravenous administration is usually 0.5 mg / kg, followed by infusion over the course of a day (the maximum daily dose is 10 mg / kg). Enoximon is administered intravenously at a dose of 2— mg / kg.
The combination of inotropic and vasodilating effect is also characteristic of beta adrenergic mimetics (izadrin, dobutamine, etc.). However, with beta-adrenergic stimulation, not only the strength, but also the heart rate significantly increases. As a result, myocardial oxygen demand rises, which
potentially dangerous, especially in patients with concomitant coronary artery disease. Therefore, the use of izadrina should be limited only to short-term appointments in symptomatic bradycardia. Dobutamine has a side effect only when it is used in high doses (over 15 µg / kg * min), while at a dose of up to 10 µg / kg * min dobutamine can cause a redistribution of cardiac output in favor of myocardium and skeletal muscles.
Among other adrenomimetics, dopamine should be distinguished, which, along with a powerful inotropic effect, has a dilating effect on the vessels of the kidneys, heart, brain and intestines, improving their blood circulation. Only at a dose in excess of 10 µg / kg * min, dopamine also affects alpha-adrenoreceptors, causing vasoconstriction and an increase in vascular resistance, and the minute blood circulation may even decrease. Therefore, the appointment of dopamine in such a dose and more inappropriate and, if the critical degree of hypotension persists, should proceed to the infusion of adrenaline or norepinephrine. The rate of adrenaline injection is 0.1 µg / kg * min, in the absence of effect, the dose is increased.
If the cause of circulatory failure is the pathological expansion of peripheral vessels, alpha-adrenomimetics (mezaton, ephedrine) or etyron — a vasopressor of myotropic action (300 mg of the drug intravenously in 100 ml of 0.9% sodium chloride solution) are used.
To increase the sensitivity of receptors to catecholamines, stabilize cell membranes and protect them from the action of toxic factors, glucocorticoids are prescribed (up to 300 — mg of prednisolone per day), and panangin, B vitamins, cocarboxylase are used to improve energy and plastic processes in the myocardium. (150–300 mg), riboxin (5– ml 2% solution per day), neoton (0.5– g / day).
It is more difficult to eliminate circulatory failure, if it is due to the significant reduction in the small circle due to the operation and the initially low reserves. This rather rare situation occurs when pneumonectomy is performed in elderly patients with concomitant widespread atherosclerosis, chronic bronchitis and pulmonary emphysema and is manifested by the development of persistent hypotension immediately after ligation of the pulmonary artery or a gradual decrease in blood pressure to critical values within a few hours after surgery. The clinical picture in this condition is peculiar and is characterized by a relatively stable general condition of the patient and the absence of other clinical signs of impaired blood circulation — the integument remains warm and moist, normal color, a satisfactory diuresis rate, a good pulse filling, tachycardia does not increase. Attempts to restore cardiac output and blood pressure by infusing dopamine or adrenaline only lead to an increase in the pulse rate and the development of arrhythmia. Permanent drip intravenous nitroglycerin provides for the restoration and maintenance of blood pressure, blood flow velocity and oxygen transport above critical. In general, the appointment of nitrates (usually from 1 day after surgery, patients take sustak-forte 1 tab. 3 times a day or nitrogranulong 1 tab. 2 times a day) is necessary for all patients who underwent lung resection in a volume of lobectomy or more. In this case, the purpose of the use of these drugs is not so much the prevention of myocardial ischemia, as a decrease in the degree of hypertension in the pulmonary circulation.
A more frequent cause of circulatory failure, in particular circulatory hypodynamia, after lung surgery is energy deficiency, which regularly accompanies urgent compensatory reactions, with characteristic changes in basic metabolic processes and the mobilization of all
functional reserves. The intensity of these catabolic disorders, i.e. The “price” of compensation reflects the adequacy of the body’s protection against damage and, therefore, is determined by the effectiveness of the entire system of intensive therapy of the operative and postoperative periods. In any case, the energy and metabolic needs of the tissues and the body as a whole after the operation always increase and require the inclusion in the treatment program of appropriate activities – high-energy nutrition, the appointment of cardiac glycosides, anabolic steroids (retabolil 1 ml every other day for the first week), vitamins.
We emphasize that circulatory hypodynamia is not the only consequence of the energy deficit. No less important are violations of reparative processes in the wound and pleural cavity, as well as inhibition of immunity. That is why prophylactic antibiotic therapy, which usually involves intravenous the introduction of broad-spectrum antibiotics during surgery and their subsequent daily elevation of pleural exudate are not always able to prevent the development of infectious complications. More correct and useful is the purposeful and methodical application of the entire system of intensive therapy during the operative and postoperative periods. Only in this case the necessary end result can be achieved – the recovery of a person with a relatively stable long-term adaptation to new conditions of existence.