Systemic and mesenteric hemodynamics, metabolism, and intestinal tonometry in a rat model of supraceliac aortic cross-clamping and declamping

Effects of dopexamine in a rat model of supracoeliac aortic cross-clamping and declamping

This experimental study in rats was designed to demonstrate effects of dopexamine (3 microg kg(-1) min(-1), n = 6) or physiologic saline solution (n = 6) on systemic as well as regional perfusion during 30 min of supracoeliac aortic cross-clamping and during 180 min of reperfusion following declamping. Rats were surgically instrumented with arterial, right atrial and portal venous catheters, ultrasonic flow probes around the abdominal aorta, superior mesenteric and carotid artery, and a paediatric tonometer for intestinal mucosal PCO(2) measurement. During 120 min of reperfusion, fluid resuscitation was titrated to keep abdominal aortic blood flow above 80% of baseline values. We found that during cross-clamping, values of arterial lactate (p = 0.002) and intestinal tonometric PCO(2) (p = 0.018) were higher in the dopexamine group than in the control group.

Influence of dobutamine on the variables of systemic haemodynamics, metabolism, and intestinal perfusion after cardiopulmonary resuscitation in the rat

BACKGROUND

Global left ventricular dysfunction after successful resuscitation from cardiac arrest may be treated successfully with dobutamine but the effects on intestinal perfusion are unknown.

METHODS

In 24 male Sprague-Dawley rats ventricular fibrillation was induced. After 4 min of untreated cardiac arrest, precordial chest compression was performed for 4 min; adrenaline (epinephrine) (90 microg kg(-1)) was injected, followed by defibrillation. Return of spontaneous circulation was achieved in 18 animals, which were allocated to receive saline 0.9% (control group, n = 6), dobutamine at 5 microg kg(-1) min(-1) (n = 6) or dobutamine at 10 microg kg(-1) min(-1) (n = 6). Measurements of haemodynamic variables and intestinal tonometer P(CO2) were made before induction of ventricular fibrillation and 15, 30, 60, and 120 min postresuscitation.

RESULTS

At 120 min postresuscitation, mean aortic pressure was 82 +/- 20, 104 +/- 19, and 113 +/- 15 mmHg for the control group, the dobutamine (5 microg kg(-1) min(-1)) group and the dobutamine (10 microg kg(-1) min(-1)) group (P < 0.05 for comparison of the dobutamine (10 microg kg(-1) min(-1)) group versus the control group). Respective abdominal aortic blood flow was 107 +/- 16, 133 +/- 49, and 145 +/- 18 ml min(-1) kg(-1) (P < 0.05 for comparison of the dobutamine (10 microg kg(-1) min(-1)) group versus the control group), and superior mesenteric artery blood flow was 25 +/- 9, 28 +/- 8, and 33 +/- 8 ml min(-1) kg(-1). Arterial lactate was significantly higher (P < 0.05) in the control group (2.3 +/- 0.6 mmol l(-1)) than in the dobutamine (5 microg kg(-1) min(-1)) group (1.6 +/- 0.3 mmol l(-1)) and dobutamine (10 microg kg(-1) min(-1)) group (1.5 +/- 0.3 mmol l(-1)). Tonometrically derived P(CO2) gap was highly elevated at 15 min of postresuscitation and returned to prearrest level at 120 min postresuscitation in all groups.

CONCLUSIONS

Dobutamine enhances the recovery of global haemodynamic and metabolic variables early after cardiac arrest.

Resuscitation from cardiac arrest with adrenaline/epinephrine or vasopressin: effects on intestinal mucosal tonometer pCO(2) during the postresuscitation period in rats

BACKGROUND

The use of vasopressin instead of adrenaline/epinephrine during resuscitation improves vital organ perfusion, but the effects on mesenteric perfusion following successful resuscitation are not fully evaluated. The present study was designed to compare the effects of vasopressin and adrenaline/epinephrine, given to rats during resuscitation from ventricular fibrillation, on to mesenteric ischaemia, as determined by intestinal mucosal tonometer pCO(2) during the postresuscitation period.

METHODS AND RESULTS

Male Sprague-Dawley rats (n=28) were allocated randomly to receive vasopressin (0.8 U/kg) or adrenaline/epinephrine (90 microg/kg) after 5 min of ventricular fibrillation. Precordial chest compression was initiated 4 min after the start of ventricular fibrillation, continued for 4 min, and followed by defibrillation. Seven of 14 (vasopressin) and 12 of 14 (adrenaline/epinephrine) rats were successfully defibrillated (P=0.10, Fisher's exact test) and observed for 60 min. Intestinal mucosal tonometer pCO(2) measurements before cardiac arrest and 15, 30, and 60 min following return of spontaneous circulation were 47+/-3, 73+/-8, 63+/-7, and 56+/-6 mmHg in the vasopressin group and 48+/-5, 78+/-7, 67+/-6, and 62+/-6 mmHg in the adrenaline/epinephrine group (P<0.05 at 60 min between vasopressin and adrenaline/epinephrine). Right atrial hemoglobin oxygen saturations at these time points were 73+/-5, 51+/-12, 58+/-11, and 63+/-5% in the vasopressin group and 76+/-7, 44+/-10, 52+/-10 and 54+/-8% in the adrenaline/epinephrine group (P<0.05 at 60 min between vasopressin and adrenaline/epinephrine).

CONCLUSIONS

We conclude that in this rat model the administration of vasopressin instead of adrenaline/epinephrine for CPR tends to be associated with lower resuscitation success, but less mesenteric ischaemia during the postresuscitation period in successfully resuscitated rats.

Regional Tissue Metabolism During Open or Endovascular Abdominal Aortic Aneurysm Surgery

OBJECTIVE

to investigate differences in regional tissue metabolism between open and endovascular aneurysm repair utilising a microdialysis technique.

MATERIALS

eight patients receiving endovascular stent grafts (STENT) and six patients undergoing open aortic surgery (OPEN) for abdominal aortic aneurysms were studied prospectively but non-randomised.

METHOD

microdialysis catheters placed subcutaneously in the pectoral and calf region, respectively.

RESULTS

microdialysate glucose levels increased in the OPEN group on the day of surgery. Microdialysate lactate levels increased transiently in the leg in the STENT group. In the OPEN group lactate increased in the leg after aortic cross-clamping. Glycerol decreased in the pectoral region in the STENT group after surgery, but remained elevated in the OPEN group.

CONCLUSION

we found indications that the metabolic impact of the two aortic procedures differ. This may be of clinical importance when selecting patients for either open aortic surgery or endovascular stentgrafting.