Robert H. Friesen

Perioperative complications in children with pulmonary hypertension undergoing noncardiac surgery or cardiac catheterization.

BACKGROUND:Pulmonary arterial hypertension (PAH) can lead to significant cardiac dysfunction and is considered to be associated with an increased risk of perioperative cardiovascular complications. METHODS:We reviewed the medical records of children with PAH who underwent anesthesia or sedation for noncardiac surgical procedures or cardiac catheterizations from 1999 to 2004. The incidence, type, and associated factors of complications occurring intraoperatively through 48 h postoperatively were examined. RESULTS:Two hundred fifty-six procedures were performed in 156 patients (median age 4.0 yr). PAH etiology was 56% idiopathic (primary), 21% congenital heart disease, 14% chronic lung disease, 4% chronic airway obstruction, and 4% chronic liver disease. Baseline pulmonary artery pressure was subsystemic in 68% patients, systemic in 19%, and suprasystemic in 13%. The anesthetic techniques were 22% sedation, 58% general inhaled, 20% general IV. Minor complications occurred in eight patients (5.1% of patients, 3.1% of procedures). Major complications, including cardiac arrest and pulmonary hypertensive crisis, occurred in seven patients during cardiac catheterization procedures (4.5% of patients, 5.0% of cardiac catheterization procedures, 2.7% of all procedures). There were two deaths associated with pulmonary hypertensive crisis (1.3% of patients, 0.8% of procedures). Baseline suprasystemic PAH was a significant predictor of major complications by multivariate logistic regression analysis (OR = 8.1, P = 0.02). Complications were not significantly associated with age, etiology of PAH, type of anesthetic, or airway management. CONCLUSION:Children with suprasystemic PAH have a significant risk of major perioperative complications, including cardiac arrest and pulmonary hypertensive crisis.

Correlation of abdominal site near-infrared spectroscopy with gastric tonometry in infants following surgery for congenital heart disease.

Objective: Splanchnic oximetry, as measured by near-infrared spectroscopy (NIRS), correlates with gastric tonometry as a means of assessing regional (splanchnic) oxygenation and perfusion. Design: Prospective, data-gathering study. Setting: Pediatric cardiac intensive care unit in a tertiary care children’s hospital. Subjects: Neonates and infants with congenital heart disease who underwent catheter intervention or surgical repair requiring cardiopulmonary bypass. Interventions: None. Measurements and Main Results: Twenty neonates and infants were studied within 48 hrs of surgery. We measured somatic saturation (rSO2) via NIRS sensors placed over the anterior abdomen (splanchnic bed) and dorsal lateral flank (renal bed). Somatic rSO2 readings were paired with simultaneous points of intramucosal gastric pH (pHi), measured by tonometry. The rSO2 readings were paired with serum lactate and measurements of systemic mixed venous saturation (S&OV0456;o2). There was strong correlation between the abdominal rSO2 and pHi (r = .79; p < .0001) as well as between abdominal rSO2 and S&OV0456;o2 (r = .89; p < .0001). There was also significant negative correlation between the abdominal rSO2 and serum lactate (r = .77; p < .0001). Correlations between the dorsal lateral (renal) rSO2 measurements and serum lactate and S&OV0456;o2 were also significant but not as strong. Conclusions: Abdominal site rSO2, measured in infants with either single or biventricular physiology, exhibits a strong correlation with gastric pHi as well as with serum lactate and S&OV0456;o2. The results indicate that rSO2 measurements over the anterior abdominal wall correlate more strongly than flank rSO2 with regard to systemic indices of oxygenation and perfusion. This study suggests that the NIRS monitor is a valid modality to obtain an easy, immediate, and noninvasive measurement of splanchnic rSO2 in infants following cardiac surgery for congenital heart disease.

Changes in anterior fontanel pressure in preterm neonates during tracheal intubation.

Anterior fontanel pressure (AFP), a noninvasive indicator of intracranial pressure (ICP), was monitored during tracheal intubation in two groups of preterm neonates without neurologic disease. Anterior fontanel pressure was monitored and recorded continuously with a Ladd AFP monitor. Systolic and mean blood pressures were recorded at 1-min intervals. In group 1 (n = 6) patients, 0.02 mg/kg intravenous atropine was administered and awake intubation was performed. Group 2 (n = 6) patients received 0.02 mg/kg intravenous atropine and 0.1 mg/kg pancuronium and one of four anesthetics-0.75% isoflurane, 0.5% halothane, 20 μg/kg fentanyl, or 2 mg/kg ketamine-with intubation after 10 min of mask ventilation. In group 1, AFP increased from 7.7 cm H2O to 23.8 cm H2O (P > 0.05); the mean increase in AFP was 197%. Anterior fontanel pressure did not change significantly in group 2. Significant increases in AFP may increase the risk of intraventricular hemorrhage in preterm neonates. The present data indicate that indirectly measured ICP increases significantly during awake tracheal intubation in preterm neonates and that this increase can be prevented by prior administration of pancuronium and a general anesthetic.

Sedation, analgesia, and neuromuscular blockade in the pediatric intensive care unit: survey of fellowship training programs.

Objective: To survey current sedation, analgesia, and neuromuscular blockade practices in pediatric critical care fellowship training programs in the United States. Design: Questionnaire survey sent by E-mail to all program directors. The survey could be submitted either via a Web site, fax, or mail. Setting: University school of medicine. Subjects: Fifty-nine pediatric critical care fellowship training program directors in the United States, listed on the Accreditation Council for Graduate Medical Education Web site. Interventions: Survey. Measurements and Main Results: The response rate was 59.3% (35 questionnaires). Midazolam, lorazepam, morphine, and fentanyl are the most frequently used drugs in pediatric intensive care units for analgesia and sedation. Most pediatric intensive care units surveyed have a written sedation policy (66%). The majority of units responding to the survey (85.7%) routinely use a scoring system to assess agitation and pain in children, with the most common being the COMFORT score. All of the pediatric intensive care units surveyed reported weaning drugs slowly to try to prevent drug withdrawal. Movement disorders related to prolonged sedation and analgesia seem to be more common than is reported in the literature, with 65.7% of units reporting cases. There is good consensus on the indications for neuromuscular blockade, with vecuronium being the most popular drug. Conclusions: When compared with a similar survey from 1989, this survey suggests that pediatric critical care units with fellowship training programs have made some changes in their approach to sedation and analgesia over the past decade. More fellowship directors report the use of sedation protocols and better recognition, prevention, and management of drug withdrawal. Similar analgesic, sedative, and neuromuscular blocking drugs are being used but some more commonly than a decade ago.

Anesthetic management of children with pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is associated with significant perioperative risk for major complications, including pulmonary hypertensive crisis and cardiac arrest. Several mechanisms of hemodynamic deterioration, including acute increases in pulmonary vascular resistance (PVR), alterations of ventricular contractility and function and coronary hypoperfusion can contribute to morbidity. Anesthetic drugs exert a variety of effects on PVR, some of which are beneficial and some undesirable. The goals of balanced and cautious anesthetic management are to provide adequate anesthesia and analgesia for the surgical procedure while minimizing increases in PVR and depression of myocardial function. The development of specific pulmonary vasodilators has led to significant advances in medical therapy of PAH that can be incorporated in anesthetic management. It is important that anesthesiologists caring for children with PAH be aware of the increased risk, understand the pathophysiology of PAH, form an appropriate anesthetic management plan and be prepared to treat a pulmonary hypertensive crisis.

Depth of consciousness and deep sedation attained in children as administered by nonanaesthesiologists in a children's hospital

Background:  Sedation of children is administered by nonanaesthesiologists in a variety of locations within our childrens hospital. The purpose of this study was to assess the depth of sedation administered to children in four locations using the Bispectral Index (BIS) and the University of Michigan Sedation Scale (UMSS).

Indirect Measurement of Blood Pressure in Neonates and Infants Utilizing an Automatic Noninvasive Oscillometric Monitor

An indirect automatic blood pressure (BP) monitor utilizing the oscillometric principle and a microprocessor is now available for use in infants. This device was evaluated by comparing its systolic BP determinations with simultaneous Doppler systolic BP determinations in neonates and infants undergoing general anesthesia. Five determinations each were made in 125 babies who were grouped according to age. Correlation coefficients of the paired BP determinations were: in 27 premature neonates, r = 0.82; in 24 term neonates, r = 0.93; in 47 infants aged 5 to 13 weeks, r = 0.92; and in 27 infants aged 14 to 26 weeks, r = 0.94. The device was also evaluated by comparing its BP determinations with those of indwelling arterial lines present in 20 additional infants (five determinations each). Correlation coefficients were 0.96 for systolic determinations and 0.94 for diastolic determinations. No morbidity or significant technical problems were noted. It was concluded that the device is an accurate, safe, and easy noninvasive method for monitoring BP in infants.

Modified ultrafiltration attenuates dilutional coagulopathy in pediatric open heart operations.

BACKGROUND Extreme hemodilution caused by relatively large prime volumes required for cardiopulmonary bypass in infants causes a dilutional coagulopathy, characterized by low concentrations of fibrinogen and other circulating coagulation factors. Modified ultrafiltration results in hemoconcentration and is associated with decreases in postoperative bleeding and transfusion requirements in children. This study was undertaken to quantify the effect of modified ultrafiltration on concentrations of fibrinogen, plasma proteins, and platelets in infants and small children. METHODS Twenty patients less than 15 kg were studied. Cardiopulmonary bypass circuits were primed with crystalloid solutions. Red blood cells were added during cardiopulmonary bypass for hematocrits less than 15%. Colloid solutions were not administered. Concentrations of fibrinogen, plasma proteins, and platelets, and hematocrit were measured before cardiopulmonary bypass, before modified ultrafiltration, and after modified ultrafiltration. RESULTS Modified ultrafiltration was associated with significant (p < 0.001) increases in hematocrit (19% +/- 6% to 31% +/- 9%), fibrinogen (65 +/- 29 to 101 +/- 45 mg/dL), and total plasma proteins (2.7 +/- 0.3 to 4.9 +/- 0.7 g/dL), but no change (p = 0.129) in platelet count. CONCLUSIONS We conclude that modified ultrafiltration significantly attenuates the dilutional coagulopathy associated with cardiopulmonary bypass in infants.

A comparison of remifentanil and fentanyl for fast track paediatric cardiac anaesthesia.

Summary Background: Fast track anaesthetic protocols for cardiac surgical patients have been developed to facilitate early tracheal extubation. We compared anaesthetics based on either remifentanil or fentanyl for fast track paediatric cardiac anaesthesia.

Cardiovascular effects of inhalation induction with isoflurane in infants.

We evaluated hemodynamic changes during inhalation induction of isoflurane anesthesia in 60 healthy infants aged 5-26 weeks who were randomly divided into two groups of 30 patients each. In group 1 anesthesia was induced using isoflurane in concentrations that were increased to 3.5%. In group 2, 0.02 mg/kg of atropine was given intramuscularly before induction of anesthesia, as in group 1. In both groups, N2O (3 L/min) and O2 (2 L/min) were administered using a nonrebreathing system. Heart rate (HR) and blood pressure (BP) were recorded at 1-min intervals for 20 min. HR decreased 32% in group 1 and 20% in group 2; BP decreased 40% in group 1 and 38% in group 2. During isoflurane induction in infants, both HR and BP are depressed. Premedication with atropine minimizes the depression of HR, but does not affect the change in BP.We evaluated hemodynamic changes during inhalation induction of isoflurane anesthesia in 60 healthy infants aged 5–26 weeks who were randomly divided into two groups of 30 patients each. In group 1 anesthesia was induced using isoflurane in concentrations that were increased to 3.5%. In group 2, 0.02 mg/kg of atropine was given intramuscularly before induction of anesthesia, as in group 1. In both groups, N2O (3 L/min) and O2 (2 L/min) were administered using a nonrebreathing system. Heart rate (HR) and blood pressure (BP) were recorded at 1-min intervals for 20 min. HR decreased 32% in group 1 and 20% in group 2; BP decreased 40% in group 1 and 38% in group 2. During isoflurane induction in infants, both HR and BP are depressed. Premedication with atropine minimizes the depression of HR, but does not affect the change in BP.