Fibrinolysis in pediatric patients undergoing cardiopulmonary bypass

Thromboelastographic evaluation of the influence of fibrinolysis on blood loss and blood product transfusions in children during cardiac surgery. Prospective study. University-affiliated, pediatric medical center. Two hundred seventy-eight consecutive children undergoing cardiac surgery. Blood sampling for coagulation tests, including native and protamine-modified thromboelastography. Blood coagulation tests were measured before, during, and after cardiopulmonary bypass (CPB). Demographic data, perioperative blood loss, and blood product transfusions were prospectively recorded. Fibrinolysis was defined as thromboelastography of A30/MA less than 0.85 (MA, maximum amplitude; A30, amplitude 30 minutes after MA) and was noted in 3% of children pre-CPB, 16% during CPB, and 3% post-CPB. Fibrinolysis before CPB was associated with poor cardiac output. Fibrinolysis during CPB occurred in young children (aged 350 ± 836 days) undergoing complex surgery with prolonged CPB (119 ± 48.8 minutes) and deep hypothermia (25.6°C ± 4.7°C). These patients received blood products after CPB and were not fibrinolytic after transfusion. They incurred similar blood loss (in mL/kg) and received similar volumes of blood products (mL/kg) as age-matched and surgery-matched patients without fibrinolysis. A group of children at risk for fibrinolysis during CPB was identified. However, fibrinolysis during CPB did not influence blood loss or the total volume of blood products transfused.     

Patient-controlled Antiemesis: A Randomized, Double-Blind Comparison of Two Doses of Propofol versus Placebo

Background: The role of propofol for the management of postoperative nausea and vomiting (PONV) is not well established. This study determines the efficacy of small doses of propofol administered by patient-controlled device for the treatment of PONV.

Methods: Patients presenting for ambulatory surgery received a standardized general anesthetic. Those who experienced significant nausea or emesis within 1 h of arrival in the recovery room were randomized to receive repeated doses of propofol 20 mg (P-20), propofol 40 mg (P-40), or intralipid (placebo) on demand. Study medications (in equal volumes) were administered with a patient-controlled delivery device for 2 h. A lockout interval of 5 min between doses was used. The following parameters were assessed: nausea, vomiting, rescue antiemetic use, recovery profile, study drug administration history, and satisfaction with treatment.

Results: Sixty-nine patients participated in the study. Patient demographics were similar. The average nausea score for a patient in the P-20 and P-40 groups was 25% and 29% less, respectively, compared with placebo during the study period (P < 0.05). This difference was apparent 15 min after initiation of therapy. More placebo patients vomited (P-20, 12%; P-40, 23%; placebo, 56%; P = 0.003) and needed rescue antiemetics (P-20, 17%; P-40, 23%; placebo, 70%; P = 0.001) compared with treatment groups. Sedation scores were similar between groups. Propofol-treated patients had shorter stays in the post-anesthesia care unit (PACU; P-20, 131 +/- 35 min [mean +/- SD]; P-40, 141 +/- 34 min; placebo, 191 +/- 92 min; P = 0.005) and higher satisfaction with their control of PONV than placebo (P < 0.01).     

Lorazepam as a premedicant for day-case surgery: an assessment

The sedative effect of 2 mg of lorazepam was assessed in eleven patients undergoing minor "day case" surgery and the results compared with a control group of eleven patients receiving a placebo. Sedation was assessed by a scoring method and quantified in terms of change in plasma cortisol levels. The results indicate that 2 mg of oral lorazepam produces good sedation (superior to nitrazepam in terms of plasma cortisol reduction) and has a postoperative anti-emetic effect but its prolonged duration of action makes it unsuitable for patients returning home within 8 hours of premedication.     

Effect of lidocaine onin Vivo hepatic function

Lidocaine is administered to assess donor or recipient liver function during hepatic transplantation. This study was performed to determine whether lidocaine administered at a constant concentration affected hepatic function or had demonstrable effects on hepatocellular ultrastructure. Fourteen pigs were randomly allocated to receive either a two-stage infusion of lidocaine hydrochloride or of saline. Transhepatic blood samples were taken and ultrasonic portal venous and hepatic arterial blood flow readings made on animals anesthetized with isoflurane in nitrous oxide. Liver biopsies were taken for histological analysis and determination of adenine nucleotide status prior to and after 2 hr of the two-stage infusion. A mean systemic constant plasma lidocaine concentration of 5.9 g/ml was achieved during the second hour of infusion. There were no differences between the two groups in a large number of indices of hepatic function and plasma composition prior to and during the second hour of the respective infusions. Hepatic blood flow was also similar at these times. On histological examination there were no electron microscopic changes that could be specifically attributed to the administration of lidocaine. However, there were progressive changes with time. This study suggests that in anesthetized pigs a constant lidocaine concentration of about 6 g/ml has no detrimental effect on hepatic function. Progressive hepatic ultrastructural changes occurred that could not be attributed to the administration of lidocaine. These may be the result of anesthetic administered or the surgery performed.Support was gratefully received from the Medical Research Council of South Africa and from the Mauerberger Foundation.     

The effect of age on the dose of remifentanil for tracheal intubation in infants and children

Introduction: This study aimed to determine the age‐specific bolus dose of remifentanil (ED₅₀) to facilitate tracheal intubation without the use of neuromuscular blocking agents. Methods: ASA 1–2 subjects were recruited into three groups of 0–3 months (group I), 4–12 months (group II), and 1–3 years (group III) of age. A sequential up‐and‐down design determined the remifentanil bolus dose, which was initially started at 3 mcg·kg^?1 and adjusted in 1 mcg·kg^?1 increments (range 1–6 mcg·kg^?1). Following pretreatment with glycopyrrolate 10 μg·kg^?1 and an induction dose of propofol 5 mg·kg^?1, remifentanil was administered with a blinded study investigator commencing tracheal intubation after 60 s. After tracheal intubation, the time to return of spontaneous ventilation was measured. Logistic regression was used to predict the ED₅₀ and ED₉₅ of remifentanil. Results: Sixty‐four subjects were recruited. Tracheal intubation was successful at first attempt in over 90% of subjects in each age group. Satisfactory intubating conditions were achieved in 85%, 63%, and 75% of subjects in groups I, II, and III, respectively. The logistic regression results for ED₅₀ (95% CI) were 3.1 (2.5–3.8), 3.7 (2.0–5.4), and 3.0 (2.1–3.9) mcg·kg^?1, and ED₉₅ (95% CI) were 5.0 (3.0–7.0), 9.4 (1.5–17.4), and 5.6 (2.9–8.4) mcg·kg^?1 in groups I, II, and III, respectively. Infants aged 4–12 months (group II) showed a marked variability in dose response; however, the mean ED₅₀ and ED₉₅ were not different to groups I and III. Older children had a longer duration of apnea than infants, 331 vs 180 s (P < 0.05). Discussion: The ED₅₀ of remifentanil for tracheal intubation was higher in all age groups than previously reported. Ideal intubating conditions were achieved in 50% of subjects with remifentanil doses of 3.1–3.7 mcg·kg^?1. Higher doses will be required for higher success rates and with anticholinergic pretreatment, doses of up to 6 mcg·kg^?1 were tolerated, without adverse effects, in two patients. Further investigation of the variability in dose response in infants and assessment of the safety this technique is warranted.