Prostacyclin in Septic Shock: Results

Prostacyclin in Septic Shock: ResultsTable 3 lists the hemodynamic variables, and Table 4 lists the O2 transport variables, at baseline, with PGI2 infusion, and 30 and 60 min after infusion. The PGI2 infusion produced marked vasodilatation as evidenced by significant reductions in systemic vascular resistance (33 percent), MAP (18 percent), pulmonary capillary wedge pressure (12 percent), and calculated coronary artery perfusion pressure (20 percent) (p<0.05). The effects were demonstrable up to 30 min after stopping the infusion (Tables 3 and 4).
The PGI2 infusion also led to a significant fall in arterial oxygen tension from 115 ± 24 to 79 ± 15 mm Hg (p<0.01), with significant increases in the calculated alveolar-arterial oxygen tension gradient from 149 ±85 to 185 ±79 (p<0.01), and pulmonary shunt from 13 ±7 percent to 17 ±7 percent (p<0.01). Despite these changes, a 17 percent increase in cardiac index after the administration of PGI2 resulted in a 14 percent increase in D02 which was already at baseline 750 ml/min/m2.
When measurements of the V02 were calculated from the respiratory gases, the V02 was unchanged after PGI2 infusion (165 ±30 vs 160 ±29 ml/min/ m2). By the simultaneous cardiovascular Fick calculations, there was a small (7 percent) (p<0.05) increase in V02 review buy birth control. This calculated increase in V02 was not different between the 2 survivors and the 13 nonsurvivors. When the V02 values from the two independent methods were directly compared, there was no significant difference between them. Figure 1 compares the V02/D02 relationships from the two independent V02 calculations before and after PGI2 for the individual patients. Two conclusions are apparent from these graphs. The more horizontal lines from the direct respiratory gas measurements contrast with the more sloping lines from the indirect Fick calculations. Second, within each method, the effects in the patients who began with lower absolute D02 values are not substantially different from those who began with higher D02 values.
The oxygen extraction ratio remained nearly unchanged in both the survivors and the nonsurvivors. Thirty minutes after stopping the PGI2 infusion, D02 remained significantly increased by V02 did not differ from baseline values. Sixty minutes after stopping the infusion, neither D02 nor V02 differed significantly from baseline values.
The blood lactate values at baseline were within our normal laboratory range (<1.9 mmol/L) in all but four patients, who all subsequently died. The only difference these patients exhibited with PGI2 infusion that differed from those with lactate in the normal range was a smaller increase in D02.

Table 3—Hemodynamic Function Before, During, and After Prostacyclin (PGI2) Infusion (Means ±SD)

Parameter Mean ± SD
Heart rate, beats/min
At baseline 106 ±20
With prostacyclin 117 ±24
Mean % change + 10
30 min after PGI2 119 ±23
60 min after PGI2 111 ± 19
Mean arterial pressure, mm Hg
At baseline 82 ±17
With prostacyclin 67 ±8
Mean % change -18
30 min after PGI2 72 ±11
60 min after PGI2 88 ±16
Mean pulmonary capillary wedge pressure (PCWP), mm Hg
At baseline 16±3
With prostacyclin 14 ±2
Mean % change -12
30 min after PGI2 14±3
60 min after PGI2 15±3
Cardiac index, L/minXm2
At baseline 5.2 ±1.8
With prostacyclin 6.1 ±1.6
Mean % change +17
30 min after PGI2 6.1 ±1.6
60 min after PGI2 5.4 ±1.6
Systemic vascular resistance, dynesXsXcm
At baseline 630 ±220
With prostacyclin 424 ±138
Mean % change -33
30 min after PGI2 462 ±169
60 min after PGI2 653 ±208
Mean pulmonary artery pressure, mm Hg
At baseline 29 ±7
With prostacyclin 27 ±6
Mean % change -7
30 min after PGI2 27 ±5
60 min after PGI2 29 ±6
Pulmonary vascular resistance, dynesXsXcm
At baseline 116±78
With prostacyclin 101 ±58
With prostacyclin 101 ±58
Mean % change -13
30 min after PGI2 97 ±49
60 min after PGI2 123 ±56

Table 4—Oxygen Transport Related Variables Before, During, and After Prostacyclin (PGI2) Infusion (Means ± SD)

Parameter Mean ± SD
Oxygen delivery, mlXmin_1Xm~2
At baseline 750 ±238
With prostacyclin 852 ±214
Mean % change +14
30 min after PGI2 854 ±200
60 min after PGI2 775±224t
Oxygen consumption by respiratory gases, mlXmin lXm 2
At baseline 165 ±30
With prostacyclin 160 ±29
Mean % change -3
30 min after PGI2 157 ±31
60 min after PGI2 161 ±27
Oxygen consumption by cardiovascular Fick, mlXmin *Xm 2
At baseline 151 ±41
With prostacyclin 162 ± 311
Mean % change +7
30 min after PGI2 167 ±40
60 min after PGI2 165 ±39
Oxygen extraction ratio, %
At baseline 21 ±6
With prostacyclin 20 ±5
Mean % change -5
30 min after PGI2 20 ±6
60 min after PGI2 22 ±6
Initial blood lactate values, mmol/L 1.42 ±0.62

Figure-1

Figure 1. Top (A), Oxygen uptake calculated from the reverse Fick principle in relation to oxygen delivery; and bottom (B), oxygen uptake measured from the respiratory gases in relation to oxygen delivery before and during prostacyclin infusion in the patients with septic shock. Patients are represented by circles. Solid symbols denote the values determined before infusion, and open symbols are the values determined at 60 min. Solid line, nonsurvivors; dotted line, survivors.

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