Correlation between the Change of Mean Arterial Pressure and the Change of Percutaneous Oxygen Saturation in Patients with Tetralogy of Fallot / 대한마취과학회지

BACKGROUND: Hypoxia often occurs during anesthesia of patients with tetralogy of Fallot (TOF). The factors that determine pulmonary circulation and oxygenation in patient with TOF are the degree of obstruction of right ventricular outflow tract (RVOT), right ventricular filling pressure, systemic vascular resistance, loss of negative pleural cavity pressure by thoracotomy, change of pulmonary vascular resistance due to positive pressure ventilation and degree of arteriopulmonary collateral connection. Hence pulse oximetry is a noninvasive technique for measuring arterial O2 saturation continuously, this study examined the correlation between the change of percutaneous arterial oxygen saturation (delta SpO2) and the change of mean arterial pressure (delta MAP) using pulse oximetry in these patients. METHODS: Twenty pediatric patients undergoing modified Blalock-Taussig shunt or total corrective operation were prospectively investigated. Immediately after induction, baseline values of MAP and SpO2 were determined and if there were some changes in SpO2 from baseline during operation, MAP on that value of SpO2 were collected. If SpO2 reduced, patients were treated with infusion of fresh frozen plasma or pentastach (2-10 ml/kg), injection of phenylephrine (10 microgram/kg) or esmolol (0.5 mg/kg). RESULTS: Intravascular volume loading only was executed in 4 patients, intravascular volume loading and phenylephrine administration was executed in 11 patients, and intravascular volume loading, phenylephrine and beta-blocker administration was executed in 5 patients. There were no significant correlation between delta MAP and delta SpO2 from linear correlation and regression analysis (r=0.23, p<0.05). CONCLUSIONS: Because delta SpO2 were not closely related with delta MAP and above mentioned factors could act closely among each others, meticulous anesthetic management is necessary during palliative or total corrective operation in patients with TOF.

Development of Pressure Gradient between Radial and Femoral Artery due to Aortic Cannula Malposition in Pediatric Cardiac Surgery / 대한마취과학회지

BACKGROUND: Appropriate placement of aortic and venous cannulas is important to ensure effective systemic perfusion. The malposition of the aortic cannula may promote preferential flow down the aorta or induce flow to aortic arch vessels causing pressure gradient between mean radial arterial pressure (RAP) and femoral arterial pressure (FAP). In this study we compared mean radial to femoral artery pressure gradient before and immediately after aortic cannulation and during cardiopulmonary bypass (CPB). METHODS: Ninety two pediatric patients undergoing open heart surgery were examined. After induction of anesthesia RAP and FAP were measured. The pressure gradient was measured before and after aortic cannulation, 15, 30 and 60 minutes after aortic cross clamping (ACC). When the pressure gradient of more than 10 mmHg developed, the surgeon was recommended to manipulate position of the aortic cannula. If the pressure gradient returned to pre-CPB level after manipulation, the pressure gradient was considered to develop due to aortic cannula. The age, presence of cyanosis, adjustment of shape of aortic cannula tip before cannulation and side of radial artery cannulation as factors developing pressure gradient were examined. RESULTS: Fifteen patients (16.3%) developed pressure gradient due to position of aortic cannula. Two patients (2.2%) developed immediately after aortic cannulation and fourteen patients (15.2%) during CPB. There was no statistically significant factor developing pressure gradient except non-cyanotic disease. CONCLUSIONS: The pediatric patient could develop pressure gradient due to malposition of aortic cannula frequently during CPB. Therefore, the simultaneous monitoring of RAP and FAP may be beneficial for managing CPB in pediatric cardiac surgery.

Changes of Blood Glucose and Insulin under Different Fentanyl Dosage in Neonates and Infants Undergoing Open Heart Surgery / 대한마취과학회지

Background: Hyperglycemia during cardiopulmonary bypass may increase the incidence and severity of neurologic deficits that may result from cerebral ischemia. Moderate hyperglycemia has been noted to occur in pediatric patients undergoing cardiac surgery despite measures such as eliminating dextrose from the CPB clear pump priming solution and from the intra-operative iv fluids. To ameliorate the hormonal and hemodynamic stress responses during cardiac surgery in neonates, infants and children, high dose fentanyl anesthesia is widely used. The authors wished to determine prospectively whether fentanyl dosage is associated with reduced blood glucose or not in pediatric patients undergoing cardiac surgery. METHODS: Twenty four pediatric patients undergoing cardiac surgery were allocated randomly into 3 groups who received 25 g/kg fentanyl, 50 g/kg fentanyl or 75 g/kg fentanyl before CPB. The changes of plasma glucose and insulin levels were observed after sternotomy, on bypass, 30 min after bypass, off bypass, and the end of the operation. RESULTS: Blood glucose levels were not increased after sternotomy, but significantly increased at bypass to the end of the operation in all fentanyl dosage groups. Plasma insulin level increased, but statistically not significant. Different fentanyl dosage (25~75 g/kg) is not associated with differences in blood glucose level. CONCLUSION: At a dosage of 25~75 g/kg fentanyl anesthesia during pediatric open heart surgery were associated with no differences and below 250 mg/dl of blood glucose level and no significant changes in insulin level.

Cardiovascular Effects of Pancuronium, Vecuronium and Pipecuronium during High-Dose Fentanyl Anesthesia in Neonates, Infants and Children / 대한마취과학회지

BACKGROUND: High dose fentanyl for cardiac surgery in neonates, infants and children can cause severe bradycardia and chest wall rigidity that result in decreased cardiac output and oxygen desaturation due to fixed stroke volume in pediatric patients. To ameliorate the effects of fentanyl, it is common to administer neuromuscular blocking drugs with wanted cardiovascular side effects. This study was designed to compare the cardiovascular variables and oxygen saturation among different muscular relaxants in high dose fentanyl anesthesia. METHODS: Thirty pediatric cardiac patients were allocated randomly into three muscle relaxant groups treated with 0.2 mg/kg pancuronium (n=10), 0.2 mg/kg vecuronium (n=10) or 0.2 mg/kg pipecuronium (n=10) after receiving an initial bolus dose of 25 g/kg of fentanyl. Changes of heart rate (HR), mean arterial blood pressure (MAP), rate-pressure-product (RPP) and oxygen saturation (SpO2) were observed. The same cardiovascular variables were also observed 1 and 2 minutes after the second bolus dose of 25 g/kg fentanyl and compared to the results among muscle relaxants. RESULTS: HR, MAP and RPP decreased significantly (p<0.05) 1 and 2 minutes after injection of the 1st fentanyl, which returned to levels above the control value after administration of pancuronium, vecuronium or pipecuronium. Among muscle relaxants, pancuronium caused the most rapid and significantly high level compared to the control value in HR and MAP. Next was pipecuronium and then vecuronium. In clinical setting, SpO2 was decreased after the 1st fentanyl injection and increased after the injection of muscle relaxants, but not significant statistically. CONCLUSION: In view of hemodynamic changes, pancuronium is most efficient and rapid in returning the hemodynamic variables that was decreased after high dose fentanyl anesthesia in neonates, infants and children whose cardiac output was dependent on HR due to relatively fixed stroke volume.