Anterior cruciate ligament injuries in growing skeleton.

Anterior cruciate ligament (ACL) injuries in the adult patients are thoroughly studied and published in orthopedic literature. Until recently, little was known about similar injuries in skeletally growing patients. The more frequent involvement of this age group in various athletic activities and the improved diagnostic modalities have increased the awareness and interest of ACL injuries in skeletally immature patients. ACL reconstruction in growing skeleton is controversial and carries some risks to the tibial and femoral growth plate. A guarded approach to ACL reconstruction is recommended in skeletally immature patients. Modification of activity of ACL injured young patient, proper rehabilitation and prudent planning of adolescent age ACL reconstruction carries the least risks of growth plate violation.

The effects of melatonin premedication on propofol and thiopental induction dose-response curves: a prospective, randomized, double-blind study.

BACKGROUND: The effect of melatonin on the intraoperative requirements for i.v.anesthetics has not been documented. We studied the effect of melatonin premedication on the propofol and thiopental dose-response curves for abolition of responses to verbal commands and eyelash stimulation. METHODS: This prospective, randomized, double-blind study included 200 adults with ASA physical status I. Patients received either 0.2 mg/kg melatonin or a placebo orally for premedication (n = 100 per group). Approximately 50 min later, subgroups of 10 melatonin and 10 placebo patients were administered various doses of propofol (0.5, 1.0, 1.5, 2.0, or 2.4 mg/kg) or thiopental (2.0, 3.0, 4.0, 5.0, or 6.0 mg/kg) for anesthetic induction. The ability of each patient to respond to the command, "open your eyes," and the disappearance of the eyelash reflex were assessed 60 s after the end of the injection of propofol or thiopental. Dose-response curves were determined by probit analysis. RESULTS: Melatonin premedication decreased thiopental ED50 values for loss of response to verbal command and eyelash reflex from 3.4 mg/kg (95% confidence interval, 3.2-3.5 mg/kg) and 3.7 mg/kg (3.5-3.9 mg/kg) to 2.7 mg/kg (2.6-2.9 mg/kg) and 2.6 mg/kg (2.5-2.7 mg/kg), respectively (P < 0.05). Corresponding propofol ED50 values decreased from 1.5 mg/kg (1.4-1.6 mg/kg) and 1.6 mg/kg (1.5-1.7 mg/kg) to 0.9 mg/kg (0.8-0.96 mg/kg) and 0.9 mg/kg (0.8-0.95 mg/kg), respectively (P < 0.05). CONCLUSIONS: Melatonin premedication significantly decreased the doses of both propofol and thiopental required to induce anesthesia.

The dose of succinylcholine required for excellent endotracheal intubating conditions.

In this prospective, randomized, double-blind, placebo-controlled study, we attempted to define the dose of succinylcholine that provides excellent intubation conditions in patients within 60 s during simulated rapid-sequence induction of anesthesia. Anesthesia was induced in 180 patients with 2 microg/kg fentanyl and 2 mg/kg propofol. After loss of consciousness, patients were randomly allocated to receive 0.3, 0.5, 1.0, 1.5, or 2.0 mg/kg succinylcholine or saline solution (control group). Tracheal intubation was performed 60 s later. A blinded investigator performed all laryngoscopies and graded intubating conditions. Intubating conditions were excellent in 0.0%, 43.3%, 60.0%, 63.3%, 80.0%, and 86.7% of patients after 0.0, 0.3, 0.5, 1.0, 1.5, and 2.0 mg/kg succinylcholine, respectively. The incidence of excellent intubating conditions was significantly more frequent (P < 0.001) in patients receiving succinylcholine than in the controls and in patients who received 2.0 mg/kg succinylcholine (P < 0.05) than in those who received 0.3 mg/kg succinylcholine. The calculated doses of succinylcholine (and their 95% confidence intervals) that are required to achieve excellent intubating conditions in 50% and 80% of patients at 60 s are 0.39 (0.29-0.51) mg/kg and 1.6 (1.2-2.0) mg/kg, respectively. It appears that there are no advantages to using doses of succinylcholine larger than 1.5 mg/kg.

Succinylcholine dosage and apnea-induced hemoglobin desaturation in patients.

BACKGROUND: The authors examined the notion that a reduction in succinylcholine dose from 1 mg/kg to approximately 0.6 mg/kg would allow a faster recovery of spontaneous ventilation and reduction in the incidence of hemoglobin desaturation during the period of apnea in simulated complete upper airway obstruction situations. METHODS: This prospective, randomized, double-blind study involved 60 patients. After preoxygenation to an end-tidal oxygen concentration >90%, patients were anesthetized with 2 microg/kg fentanyl and 2 mg/kg propofol. After loss of consciousness, patients were randomly allocated to receive 0.56 or 1.0 mg/kg succinylcholine or saline (control group). Oxygen saturation was monitored continuously at the index finger. When the patient became apneic, the face mask was removed and the patient's airway was left unsupported. If the oxygen saturation decreased to 90%, the face mask was reapplied, and ventilation was assisted until the patient was awake. Time from injection of the study drug to the first visible spontaneous diaphragmatic movements was noted. RESULTS: Oxygen saturation decreased <90% in 45%, 65%, and 85% of patients in the control, 0.56 mg/kg, and 1.0 mg/kg succinylcholine groups, respectively (P = 0.03). Corresponding times (mean +/- SD) to spontaneous of diaphragmatic movements were 2.7 +/- 1.2, 4.8 +/- 2.5, and 4.7 +/- 1.3 min, respectively. These times were longer (P < 0.001) after either dose of succinylcholine compared with controls. CONCLUSIONS: Reduction in succinylcholine dose from 1.0 mg/kg to 0.56 mg/kg decreased the incidence of hemoglobin saturation <90% from 85% to 65% but did not shorten the time to spontaneous diaphragmatic movements. A significant fraction of patients would be at risk if there were failure to intubate and ventilate whether succinylcholine is administered or not and regardless of the dose of succinylcholine administered.

Optimal dose of succinylcholine revisited.

BACKGROUND: The authors reappraised the conventional wisdom that the intubating dose of succinylcholine must be 1.0 mg/kg and attempted to define the lower range of succinylcholine doses that provide acceptable intubation conditions in 95% of patients within 60 s. METHODS: This prospective, randomized, double-blind study involved 200 patients. Anesthesia was induced with 2 mug/kg fentanyl and 2 mg/kg propofol. After loss of consciousness, patients were randomly allocated to receive 0.3, 0.5, or 1.0 mg/kg succinylcholine or saline (control group). Tracheal intubation was performed 60 s later. A blinded investigator performed all laryngoscopies and also graded intubating conditions. RESULTS: Intubating conditions were acceptable (excellent plus good grade combined) in 30%, 92%, 94%, and 98% of patients after 0.0, 0.3, 0.5, and 1.0 mg/kg succinylcholine, respectively. The incidence of acceptable intubating conditions was significantly greater (P < 0.05) in patients receiving succinylcholine compared with those in the control group but was not different among the different succinylcholine dose groups. The calculated doses of succinylcholine (and their 95% confidence intervals) that were required to achieve acceptable intubating conditions in 90% and 95% of patients at 60 s were 0.24 (0.19-0.31) mg/kg and 0.56 (0.43-0.73) mg/kg, respectively. CONCLUSIONS: The use of 1.0 mg/kg of succinylcholine may be excessive if the goal is to achieve acceptable intubating conditions within 60 s. Comparable intubating conditions were achieved after 0.3, 0.5, or 1.0 mg/kg succinylcholine. In a rapid-sequence induction, 95% of patients with normal airway anatomy anesthetized with 2 mug/kg fentanyl and 2 mg/kg propofol should have acceptable intubating conditions at 60 s after 0.56 mg/kg succinylcholine. Reducing the dose of succinylcholine should allow a more rapid return of spontaneous respiration and airway reflexes.