Discussion
Thermal injury disrupts normal haemostasis and sets off a cascade of events. Cellular alterations and the release of inflammatory mediators cause hypovolaemic shock. Accurate burn size estimation, correct choice of type of fluid, and appropriate subsequent fluid administration are mandatory for the improvement of survival of patients with extensive burn injuries.11
Hydroxyethyl starches are derivatives of amylopectin, which is widely used for plasma volume expansion in patients with shock, sepsis, burns, or trauma. These solutions, especially when used at a concentration of 10%, may be retained better in the circulation in capillary leak syndromes, and may reduce reperfusion injury.14 Additional advantages of Haes solutions are the low incidence of anaphylactic reactions and their efficiency in preventing venous thrombosis, both of which make them a better choice than dextran or gelatin. The effects of the early administration of Haes solutions on coagulation mechanisms have caused some concern, but they do not appear to have deleterious consequences.15
Our data suggested that the use of standard vital signs such as blood pressure, pulse rate, and urine output failed to give early warning of the inadequacy of fluid replacement in burn patients, since there was a non-significant (p > 0.05) difference between the two groups with regard to blood pressure and HR. This result was consistent with that of Holm et al.,2 who concluded that standard vital signs may be invalid as an outcome related to resuscitation goals and are too insensitive to ensure appropriate fluid replacement.
With regard to urine output, there was a significant increase (p <0.05) in the total amount of urine output in Haes-group patients compared with that in LR patients. However, during the study period, urine output in Haes-group patients increased significantly (p < 0.05) compared with output in LR patients only during the first 6 h of infusion therapy. These results are consistent with those of Nagy et al.,16 who reported that urinary output showed a significant increase within 2 h of infusion of 500 ml of Haes-Steril.
There was a significant increase (p <0.05) in COP (13% and 23%) and in CI (13% and 23%) in the LR and Haes groups, respectively. CVP increased significantly (p < 0.05) in Haes-group patients (42.3%) compared with values in LR patients (25%). These results were consistent with those of Waxman et al.17 and Hankelin et al.,18 who found that Haes-Steril 10% produced a significant increase in CI, CVP, and left and right ventricular stroke work index, but that LR solution improved CVP and did not significantly improve other haemodynamic variables.
The study revealed a significant increase (p <0.05) in VO2 in Haes-group patients compared with that in patients in the LR group. This result is consistent with those of Waxman et al.17 and Hankelin et al.,18 who reported that haemodynamic and oxygen transport variables were improved in colloid trials, whereas LR solution did not improve the patients’ cardiopulmonary conditions, and that while all colloids produced an improvement in the patients’ haemodynamics and oxygen transport conditions, a statistically significant improvement could be demonstrated only during infusion of Haes 10%.
The data obtained show a decreased serum lactate level in the two groups studied (34.2% reduced in the LR group and 32.3% in the Haes group). Serum lactate level showed a non-significant decrease (p > 0.05) in the Haes group compared with the LR group throughout the study period. There was a negative significant correlation between serum lactate and CI in both groups (r = -0.52 and -0.505, p <0.019 and 0.023, respectively). Also, there was a negative significant correlation between serum lactate and VO2 (r="-0.683" and 0.612, p="0.001" and 0.004) in both the LR and the Haes group, respectively. These results were consistent with those of Holm et al.,2 who reported that initial serum lactate levels as well as the ability to clear elevated lactate were found to be significantly associated with a higher CI and oxygen delivery rate.
The study showed a significant decrease (p <0.05) in the plasma ET-1 level at the end of the period. The plasma ET-1 level decreased by 39.6% in LR patients and by 44.5% in the Haes group. There was a significant decrease (p < 0.05) in plasma ET-1 in Haes-group patients compared with the level in LR patients, 12 h after initiation of fluid therapy. A negative significant correlation was found between plasma ET-1 levels and CI in both groups (r="-0.65" and 0.652, p="0.002," respectively). The results obtained were consistent with those of Youn et al.20 and Huribal et al.,21 who reported that ET-1 was usually detected in high concentrations a few hours post-burn and started to decline after initiation of fluid replacement therapy.
Serum urea decreased non-significantly (p > 0.05) in both the LR and the Haes groups during the study period. However, serum creatinine showed a significant decrease (p <0.05) in Haes-group patients during the study period compared with the level in patients in the LR group. The decrease in serum creatinine in patients in the study groups was manifested as a significant increase (p < 0.05) in the creatinine clearance rate in both groups; however, the creatinine clearance rate increased significantly (p < 0.05) in Haes-group patients compared with the rate detected in LR patients. The creatinine clearance rate showed a positive significant correlation with CI in both groups (r="0.518" and 0.571, p="0.019" and 0.011). These results were consistent with those of Köhler et al.,22 who reported that an infusion of 500 ml of Haes-Steril 10% increased the creatinine clearance rate within afew hours.
On the basis of the above results, we can conclude that Haes-Steril, a colloidal plasma volume substitute, can increase cardiac output and oxygen transport values and improve organ function and the overall haemodynamic situation in patients with hypovolaemic burn shock. We can also conclude that the serum lactate level correlates well with the improvement of haemodynamic parameters and can be used as a predictive parameter for such improvement.
RESUME.Les lésions thermales provoquent beaucoup de complications et de décès. La plupart des patients brûlés présentent une réduction du volume plasmatique et une augmentation du fluide interstitiel. On emploie le Haes-Steril dans la thérapie expansive pour la substitution de volume à moyen terme afin d’obtenir une amélioration plus rapide et plus profonde des variables hémodynamiques. Dans cette étude les Auteurs ont confronté les effets de la fluidothérapie aiguë avec l’emploi de la solution de Ringer lactatée (RL) et le Haes-Steril 10% sur les variables hémodynamiques, le volume d’oxygène consommé et la fonction rénale des patients brûlés. L’étude comprenait 40 patients atteints de brûlures dans plus de 15% de la superficie corporelle totale divisés en deux groupes qui ont reçu ou la solution RL ou le Haes-Steril 10%. La comparaison des résultats des deux groupes étudiés indiquait une différence non significative (p > 0.05) dans le rythme cardiaque et la tension artérielle moyenne et montrait aussi une augmentation significative (p <0.05) de la pression veineuse centrale, du débit cardiaque, de l’indice cardiaque et du VO2 dans les patients du groupe Haes par rapport aux patients du groupe RL. Ces niveaux du lactate sérique et d’endothéline plasmatique-I étaient réduits dans les deux groupes à la fin du période de l’étude et étaient corrélés en manière significative avec un indice cardiaque augmenté. La créatinine sérique diminuait en manière significative et le taux de la clearance de la créatinine augmentait dans les patients inclus dans le groupe Haes par rapport aux patients du groupe RL. Les Auteurs concluent que le Haes-Steril peut améliorer la situation complessive hémodynamique des patients atteints de brûlures et que la créatinine sérique peut être utilisée comme facteur de prédiction de l’amélioration.
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This paper was received on 15 November 2000. Address correspondence to: Prof. Salama E. Al-Hawary, M.D., Anaesthesiology, Department, Faculty of Medicine, Tanta University, Tanta, Egypt. |