Anesthetic and perioperative outcome of teenagers and adults with congenital heart disease.

OBJECTIVE: To compare the perioperative outcome of patients >or=13 years old undergoing surgery for congenital heart disease in a children's hospital by a dedicated congenital heart surgery and anesthesia team with procedure-matched younger control patients. DESIGN: Retrospective medical record review study. From October 1997 to July 2000, medical records of all patients >12 years old requiring cardiopulmonary bypass were reviewed. A control group of patients

The optimal length of insertion of central venous catheters for pediatric patients.

UNLABELLED: Incorrect positioning of central venous catheters (CVC) in infants and children may lead to serious complications such as perforation of the heart or great vessels. CVC position is not usually assessed until the first postoperative chest radiograph, potentially leaving malposition undetected for several hours. We studied a series of 452 right internal jugular and subclavian catheter placements in infants and children undergoing surgery for congenital heart disease, and measured the distance from the skin insertion site to the radiographic junction of the superior vena cava and right atrium (RA). Based on these data, the following formulae predict that a CVC will be positioned above the RA 97% of the time: correct length of insertion (cm) = (height in cm/10) - 1 for patients < or =100 cm in height, and (height in cm/10) - 2 for patients >100 cm in height. Weight-based recommendations were also developed which predict placement of CVC above the RA 98% of the time. IMPLICATIONS: This study assessed central venous catheter placement in 452 infants and children undergoing cardiac surgery. Simple, clinically useful guidelines based on height and weight were developed to prevent malposition of these catheters, which may cause serious complications such as perforation of the heart or great vessels.

Pressure control ventilation: three anesthesia ventilators compared using an infant lung model.

UNLABELLED: We compared three ventilators-Servo 900C (Siemens Medical Systems, Danvers, MA), Aestiva 3000 (Datex-Ohmeda, Madison, WI), and NAD 6000 (North American Dräger, Telford, PA)-set to deliver pressure control ventilation using an infant test lung model. Ventilator settings were selected to test "near-maximum" settings that would be used for a neonatal patient (peak inspiratory pressure [PIP] 30 cm H(2)O) or older child (PIP 60 cm H(2)O). When adjusted for set inspiratory pressure and compliance, the average tidal volume (V(t)) produced by the NAD 6000 was 5.8 mL less than the Servo 900C (P: = 0. 103), and the average V(t) produced by the Aestiva 3000 was 18.9 mL less than the Servo 900C (P: < 0.001). The Servo 900C generated increased peak pressures, tending to overshoot the set maximum inflating pressures, especially during rapid respiratory rates with decreased inspiratory times. The Aestiva 3000 did not achieve the set PIP during testing conditions of decreased inspiratory times, and the NAD 6000 was not greatly affected by changes in inspiratory time. All three ventilators measured expiratory V(t) to be larger than the actual V(t) delivered to the lung; however, the NAD 6000 was more accurate. IMPLICATIONS: There are differences in performance of ventilators when set to deliver pressure control ventilation to an infant test lung model.

Comparison of NAD 6000 and servo 900C ventilators in an infant lung model.

UNLABELLED: We compared the ability of the NAD 6000 (North American Dräger, Telford, PA) and the Servo 900C (Siemens-Elema AB, Solna, Sweden) anesthesia ventilators to maintain precise delivery of small tidal volumes (V(t)) and positive end-expiratory pressure using an infant test lung model. A variety of ventilator and lung model settings were selected to test clinical conditions simulating normal and extremely compromised lung function. Differences in ventilator output were analyzed by using an independent t-test with P <0.05 considered significant. With the ventilators set to deliver a V(t) of 30 mL, the actual delivered V(t) was significantly better for the NAD 6000 (25 +/- 2 mL) compared with the Servo 900C (18 +/- 3 mL), P <0.001. When the ventilators were set to deliver 100 mL V(t), their delivered V(t) were not significantly different, NAD 6000 (66 +/- 19 mL) and Servo 900C (60 +/- 12 mL), P = 0.09. The exhaled V(t) read by the anesthesia machines was significantly closer to the delivered V(t) for the NAD 6000 (11 +/- 9 mL) compared with the Servo 900C (37 +/- 11 mL), P < 0.001. Both ventilators maintained the end expiratory pressure delivered to the test lung within 2 cm H(2)O of the set positive end-expiratory pressure on average. As the conditions changed requiring the ventilator to develop a higher peak inflating pressure, both ventilators showed a decrease in V(t) delivered, which was proportionate to the tubing compression volume loss. IMPLICATIONS: The NAD 6000 (North American Dräger, Telford, PA) and Servo 900C (Siemens-Elema AB, Solna, Sweden) are able to precisely deliver small Tidal Volumes. They both decreased in performance when tested under extreme conditions. Earlier studies of traditional anesthesia ventilators suggest that the NAD 6000 and Servo 900C are superior pediatric ventilators.

The effect of nitrous oxide diffusion on laryngeal mask airway cuff inflation in children.

We studied the effect of nitrous oxide (N2O) diffusion on size 2 LMA cuff inflation in 52 children, 38 +/- 21 months of age. LMA cuffs were inflated with air (Group A) or 65% N2O, oxygen and halothane (Group B). Cuffs were inflated in a stepwise manner, achieving a cuff leak pressure of 17 +/- 4 cm H2O for all patients. Cuff volume and intracuff pressure increased in Group A (8.5 +/- 1.0 ml to 10.8 +/- 1.4 ml and 101 +/- 36 mmHg to 152 +/- 42 mmHg, respectively) and decreased in Group B (8.9 +/- 1.0 ml to 6.6 +/- 1.5 ml and 90 +/- 30 mmHg to 53 +/- 37 mmHg, respectively). Cuff leak pressure did not change significantly in either group. We conclude that cuff inflation with a mixture of N2O/oxygen prevents N2O diffusion into the cuff, avoiding cuff overinflation without compromising LMA function.

Positive pressure ventilation with the laryngeal mask airway in children.

We studied the safety of positive pressure ventilation (PPV) when using the size 2 laryngeal mask airway (LMA) in 46 ASA physical status I or II children (aged 38 +/- 21 mo) undergoing elective surgery. The LMA cuff was inflated in incremental steps to achieve a cuff leak pressure > or = 15 cm H2O. Abdominal circumference was measured before and after PPV in study patients, as well as in a control group managed with tracheal intubation. Cuff leak pressure was 17 +/- 4 cm H2O (range 12-34 cm H2O). Forty-five patients successfully underwent PPV. Gas leak around the LMA cuff prevented PPV in one infant. The only respiratory variable that changed significantly was end-tidal CO2, which decreased from 40 +/- 6 to 34 +/- 5 mm Hg. Abdominal circumference increased in 28 patients but was not associated with any complications. Change in abdominal circumference in the study group was not significantly different from that observed in the control group. However, abdominal circumference increased 8 cm in one study patient, prompting insertion of an orogastric tube. The size 2 LMA provides an effective airway for PPV. Mild gastric distention often occurs. The risk of clinically significant gastric distention appears to be small, but it warrants close monitoring. We conclude that with certain precautions described in the text, the size 2 LMA provides a relatively safe airway for PPV in children.

Neuromuscular effects of rocuronium in children during halothane anaesthesia.

Rocuronium bromide, a nondepolarizing muscle relaxant has been shown to have a short onset and intermediate duration of action in adults and young children. We evaluated onset time, intubating conditions, as well as duration of action of rocuronium in children ages four to 12 years during nitrous oxide-halothane anaesthesia. Following a stable recording of train-of-four (TOF) impulses at the ulnar nerve, patients were given rocuronium 600 micrograms.kg-1 intravenously. We found that the time to 90% and 100% neuromuscular (N-M) block of the (TOF) was 51 +/- 18 s and 66 +/- 32 s respectively. Intubation was achieved at 94 +/- 31 s and rated as good or excellent in all cases. Time to recovery of N-M transmission to 25%, 75% and 90% of control was 29 +/- 8 min, 42 +/- 14 min and 46 +/- 16 min respectively. Heart rate increased approximately 12 BPM after drug injection, while the blood pressure remained unchanged. From our data we conclude that, as in other age groups, rocuronium has a rapid onset, intermediate duration of action in children 4-12 years of age, and appears devoid of significant side effects.

Efficacy of transnasal butorphanol tartrate in postepisiotomy pain: a model to assess analgesia.

Butorphanol tartrate, a synthetically derived opioid agonist-antagonist analgesic, was tested in a large group of postpartum women (N = 76) to assess the safety and analgesic efficacy of a recently approved transnasal preparation of this drug in the relief of postepisiotomy pain. The safety and efficacy of intravenous and intramuscular administration of butorphanol tartrate has been established over 14 years of clinical use. The new nasal spray dosage form offers a similar degree of efficacy with a rapid onset of action. Compared with the injectables and other drugs in this class, transnasal butorphanol has a longer duration of action (4 to 5 hours). In this double-blind, parallel-group, dose-response study, 76 female patients ages 17 to 37 years with moderate to severe postepisiotomy pain were randomly assigned to receive a single dose of transnasal butorphanol (0.25, 0.5, 1, or 2 mg) or placebo. The patients were evaluated for 6 hours. The results of the study indicate that the 1-mg and 2-mg doses were associated with greater efficacy compared with placebo using several markers for efficacy, including the pain relief score and time to remedication. The drug was well tolerated, dizziness and drowsiness being the most frequently reported adverse effects. Adverse effects appeared to be dose related.

Post-caesarean section analgesia: a comparison of epidural butorphanol and morphine.

Epidural butorphanol 1, 2 and 4 mg were compared with morphine, 5 mg, for postoperative analgesia in 92 consenting, healthy, term parturients who had undergone Caesarean section under epidural lidocaine anaesthesia in a randomized double-blind study. Postoperative pain was assessed using a visual analogue scale and recorded with heart rate, blood pressure and respiratory rate. The demographic characteristics, and the incidences of primary and repeat Caesarean sections, were not different among the four treatment groups. At 15, 30, 45 and 60 min after treatment the median pain scores following butorphanol were similar and lower than those following morphine (P less than 0.05). Calculated median percentage pain relief values for butorphanol were higher than morphine at each of these times (P less than 0.05). At 90 min and 2 hr the pain scores and pain relief values were similar. Beyond 45 min the number of patients requesting supplemental medication and dropping out of the study increased progressively in both the butorphanol and morphine treated patients. The attrition profiles for butorphanol were different from morphine (P less than 0.01). The median time in the study was greater than 24 hr for morphine, and 3, 2.5 and 4 hr for butorphanol, 1, 2 or 4 mg, respectively. No patient developed a clinically important change in heart rate or blood pressure, and none experienced a decrease in respiratory rate below 12 breaths.min-1. One of 69 patients (1.4 per cent) who received butorphanol developed pruritus compared with ten (43 per cent) of 23 patients who received morphine. The global assessments of the adequacy of analgesia were indistinguishable between morphine and butorphanol. Epidural butorphanol provides safe, effective postoperative analgesia, has a prompt onset, and a limited duration.

Vecuronium for rapid-sequence intubation for cesarean section.

Because succinylcholine may occasionally be contraindicated for rapid-sequence induction in parturients, we studied the use of vecuronium in 21 patients having elective cesarean sections. Eleven patients (group 1) received 10 micrograms/kg vecuronium as a priming dose, followed 4-6 min later by 100 micrograms/kg. Ten patients (group 2) received 200 micrograms/kg vecuronium as a bolus. Onset, the time from the injection of vecuronium to maximal twitch suppression, and clinical duration, the time between vecuronium administration and return to 25% of the control twitch height, were recorded. Umbilical and maternal venous blood samples at delivery were analyzed for vecuronium concentrations. One-minute and 5-min Apgar scores and 1- and 24-h Neurologic and Adaptive Capacity Scores (NACS) were recorded. Individual tests of passive and active tone within the overall NACS profile were compared to evaluate further any residual vecuronium effects in the infants. Onset of neuromuscular blockade was 177 s in group 1 and 175 s in group 2. The corresponding clinical durations were 73 and 115 min. Maternal and umbilical venous vecuronium concentrations were 515 and 73 ng/mL in group 1 and 838 and 107 ng/mL in group 2. Seventy percent of neonates in group 1 had Apgar scores greater than 7 at 1 min, with 100% greater than 7 at 5 min. Corresponding values in group 2 infants were 50% and 80%. Fifty percent of group 1 infants had NACS of 35-40 at 1 h, and 70% at 24 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of crystalloid versus colloid infusion on peripartum colloid osmotic pressure changes.

Plasma colloid osmotic pressure acts to retain fluid in the intravascular space. Intravenous crystalloids have been identified as one of the major factors contributing to the consistent peripartum decline in colloid osmotic pressure. This study was undertaken to compare the effect of two crystalloid infusions (1000 and 2000 mL Plasma-Lyte A) and a colloid infusion (1000 mL 5% albumin) on the peripartum colloid osmotic pressure. Before elective cesarean section, 45 parturients received one of the three infusions. The lowest mean maternal colloid osmotic pressure (16.6 +/- 1.1 mmHg, P less than .05 compared with baseline) occurred in the 2000-mL crystalloid infusion group eight to 16 hours postpartum. Although the colloid osmotic pressure fell in all groups postpartum, this reduction was significantly (P less than .05) less during the first 24 hours in the colloid infusion group. Minimizing this disruption of the colloid osmotic pressure to pulmonary capillary wedge pressure gradient may be clinically important in selected patients.