Oxygen delivery-consumption relationship in adult respiratory distress syndrome patients: the effects of sepsis.

The oxygen consumption-delivery relationship (VO2/DO2) was studied in 15 sedated paralyzed patients with the adult respiratory distress syndrome (ARDS) due to multiple trauma and in whom sepsis was absent. Different levels (0 to 15 cm H2O) of positive end-expiratory pressure (PEEP) were applied. Oxygen delivery was calculated from cardiac index (thermodilution technique) and arterial oxygen content measurements. Oxygen consumption was calculated using Fick's equation. Regression lines were obtained for each patient. Oxygen supply dependency was defined as a significant (P < .05) relationship between changes in VO2 and DO2 with PEEP. Results were compared with those obtained in 18 ARDS patients in whom ARDS was due to sepsis. In nonseptic ARDS patients no significant relationship between changes in VO2 and DO2 with PEEP was found within the experimental range of DO2 on zero end-expiratory pressure (ZEEP) (347 to 845 mL/min/m2). None of these patients had multiple organ system failure (MOSF), and 73% survived. In ARDS patients in whom sepsis was present, supply dependency was present only when DO2 on ZEEP ranged between 330 and 640 mL/min/m2. All these patients developed MOSF and died. When DO2 on ZEEP ranged between 686 and 951 mL/min/m2 in septic ARDS patients, the supply dependency phenomenon was absent and only three patients developed MOSF and died (70% survivors). In almost all patients PEEP reduced DO2 and therefore worsened O2 balance by either increasing O2 extraction ratio and approaching the critical threshold for supply dependency or dismissing DO2 from the range of non-supply dependency.

Haemodynamic effects of subarachnoid blockade: 20% lignocaine versus 0.5% plain bupivacaine.

BACKGROUND: Our study compared the haemodynamic changes after spinal anaesthesia with 2% lignocaine and 0.5% plain bupivacaine. METHODS: A controlled, randomized trial was performed on 30 patients scheduled for arthroscopic knee surgery. Two percent lignocaine and 0.5% plain bupicacaine was used for spinal anesthesia. We measured cardiac output, blood pressure and level of sensory blockade before and for 25 minutes after spinal anaesthesia. RESULTS: In patients developing sensory block below T6 there were no differences between the study drugs in heamodynamic measurements. In patients who developed a sensory block at or above T6 there was a greater drop in mean arterial pressure and cardiac output and a faster decrease in heart rate in patients receiving bupivacaine. CONCLUSION: In patients developing a sensory block at or above the T6 dermatome, the decrease in cardiac output and mean arterial pressure in the first 25 min. after spinal anaesthesia is smaller if 2% lignocaine rather than 0.5% bupivacaine is used for blockade.

[The effect of positive end-expiratory pressure on gas exchange and hemodynamics]. / Uticaj pozitivnog pritiska na kraju ekspirijuma (PEEP) na gasnu razmenu i hemodinamiku.

The effects of positive end-expiratory pressure (PEEP) on arterial and mixed venous blood oxygenation as well as the effects on systemic and pulmonary circulation were studied in 15 patients with adult respiratory distress syndrome (ARDS) on mechanical ventilation. The measurements of arterial and mixed venous blood oxygen pressure (PaO2, PvO2), heart rate (HR), central venous pressure (CVP), pulmonary wedge pressure (WP), mean pulmonary arterial pressure (Ppa), mean systemic arterial pressure (Psa) and cardiac output (CO) were performed at 0, 5, 10 and 15 cm H2O PEEP. The positive effect of + 10 cm H2O on arterial oxygenation was found (PaO2 raised from 11.49 +/- 3.5 kPa to 13.3 +/- 3.3 kPa). Ppa raised too, from 23 +/- 7.6 mm Hg to 26 +/- 7 mm Hg. Psa and CO lowered at + 15 cm PEEP. Psa from 85 +/- 17 mm Hg to 73 +/- 17 mm Hg as well as CO from 8.22 +/- 1.1 l/min to 6.91 +/- 1.40 l/min. Authors conclude that PEEP can be accepted form of therapy in the treatment of refractory hypoxemia in patients with ARDS. Despite this beneficial effect, PEEP may adversely affect cardiovascular function. As with any therapy, the optimum PEEP "dose" should be tailored to each patient according to his needs and response.

[Respiratory function in patients immediately after surgery of the thorax or upper abdomen]. / Respiraciona funkcija u bolesnika neposredno posle operacije u grudnom kosu ili gornjem abdomenu.

The study deals with the patients in the first postoperative hour following the operation in the upper abdomen or thorax. We considered the respiratory function of the patients in the first postoperative hour and how the respiratory function is influenced by the residua of general anesthesia at that time. Statistically significant decrease of postoperative SaO2 values was found and many patients were hypoxemic after the operation. We found decreased minute ventilation in the first postoperative hour in both groups of patients. Anyway the minute ventilation was more decreased in the abdominal group of patients who recovered from intravenous anesthesia. The conscience as well was more slowly returned to the patients in the abdominal group. In the first 30 minutes more abdominal patients suffered from the muscular weakness following intraoperative relaxation. But this first half an hour after the operation they had satisfactory level of analgesia left. To the contrary the postoperative pain was more severe in the thoracal group of patients. Postoperative gas exchange was more often and more seriously disturbed in the thoracal group of patients who in majority suffered from previous lung disease, which means they had greater ventilation/perfusion imbalance and greater right to left shunt. In the abdominal group only the patients who had relatively short intravenous anesthesia were found hypoxemic in the first postoperative hour. We think that in these patients the gas exchange abnormalities immediately after the operation are also caused by the hypoventilation which often follows general anesthesia.

[Importance of measurement of systemic oxygen transport and tissue oxygenation in the treatment of acute respiratory insufficiency]. / Znacaj merenja sistemskog transporta kiseonika i oksigenacije tkiva za lecenje akutne respiracione insuficijence.

The patients with acute respiratory failure of different etiology are presented. The results of hemodynamic measurements together with those of oxygen transport and tissue oxygenation are given. The results reveal that in hypovolemic shock the transport system of oxygen and tissue oxygenation have been soon normalized by adequate therapy. However, more complicated is the condition of patients with sepsis and adult respiratory distress syndrome (ARDS) with disturbances in microcirculation. In them the oxygen uptake (VO2) is directly dependent upon the oxygen transport (DO2) i.e. much higher values of DO2 should be maintained by therapeutic measures than in conditions with intact microcirculation. According to their own experiences and data from the literature the authors consider that in patients with ARF in whom by the conventional methods the condition cannot be improved an invasive monitoring for following the hemodynamic measurements of oxygen transport and tissue oxygenation should be indicated for successful treatment.

[Hemodynamic effects of spinal anesthesia with 2% lidocaine in comparison to 0.5% isobaric bupivacaine]. / Hämodynamische Effekte einer Spinalanästhesie mit 2% Lidocain im Vergleich zu 0,5% isobarem Bupivacain.

BACKGROUND: Our study compared the haemodynamic changes after spinal anesthesia with 2% lignocaine and 0.5% plain bupivacaine. METHODS: A controlled, randomized trial was performed on 30 patients scheduled for arthroscopic knee surgery. 2% lignocaine and 0.5% plain bupivacaine were used for spinal anaesthesia. We measured cardiac output (electrical bioimpedance cardiography), blood pressure and development of sensory blockade before and for 25 minutes after spinal anaesthesia. RESULTS: In patients developing a sensory block below T6 there were no differences between both anaesthetics in haemodynamic parameters. But in patients developing a sensory block at or above T6 there was a greater drop in mean arterial pressure and cardiac output and a faster decrease in heart rate for bupivacaine compared to patients receiving Lignocaine. CONCLUSION: In patients developing a sensory block at or above the T6 dermatome, the decrease in cardiac output and mean arterial pressure in the first 25 min after spinal anaesthesia is smaller when 2% lignocaine rather than 0.5% bupivacaine is used for blockade.