Comparison of minimal fresh gas requirements of baby enclosed afferent reservoir and Jackson Rees anesthetic circuit for general anesthesia in spontaneously breathing children.

OBJECTIVE: The authors compared the baby enclosed afferent reservoir (Baby EAR) with the Jackson-Rees (JR) anesthesia circuit for the minimal fresh gas flow (FGF) requirement with no and clinically acceptable rebreathing in spontaneous breathing anesthesia among pediatric patients. MATERIAL AND METHOD: The present study was a randomized crossover study. Twenty patients, weighing 5 to 20 kg with ASA physical status I-II were enrolled. They were allocated to group 1 (EAR-JR) starting with Baby EAR then switching to JR or group 2 (JR-EAR), reversedpattern. After induction and intubation, anesthesia was maintainedwith a N2O/O2 combination with sevoflurane 1 to 3% and fentanyl. Starting with the first circuit, all patients were spontaneously ventilated with FGF 500 mL/kg/min for 10 minutes, and then gradually decreased by 50 mL/kg/min every five minutes. End-tidal CO2 (ETCO) and inspired minimum CO2 (imCO) were recorded until rebreathing (imCO2 >2 mmHg) occurred and continued until rebreathing was not clinically acceptable (imCO2 >6 mmHg). The anesthesia breathing circuit was switched and the procedure repeated. RESULTS: The minimal FGF at no rebreathing of Baby EAR and JR were 192.5±76.6 and 347.5±108.2 mL/kg/min; p<0.001. At acceptable rebreathing, the values were 117.5±46.7 and 227.6±90.6 mL/kg/min; p< 0. 001. CONCLUSION: Baby EAR can be used safely, effectively, and requires less FGF than JR in pediatric anesthesia in patients weighing 5 to 20 kg.

Baby EAR circuit: a clinical determination of optimal fresh gas flow in spontaneous breathing anesthesia.

BACKGROUND: Baby EAR circuit is a new modified enclosed afferent reservoir anesthetic breathing system invented to use in pediatric patients. By following His Majesty the King of Thailand's self-sufficiency philosophy, the circuit is simplymade of low-cost and easy-to-find materials in the operating room. OBJECTIVE: Investigate clinical use of the circuit and to find the optimal fresh gas flow in spontaneous breathing anesthesia. MATERIAL AND METHOD: A prospective descriptive study was conducted in pediatric patients, who weighed 5-20 kg, anesthetized for surgery and divided into three groups of body weight: groups I (5 - <10 kg), groups II (10 - <15 kg), groups III (15-20 kg). The Baby EAR circuit was used for general anesthesia with endotracheal tube and spontaneous breathing. Different fresh gas flow of 4, 3.5, 3, 2.5, 2, and 1.5 liter per minute (LPM) was used consecutively The authors recorded end-tidal carbon dioxide (EtCO) and mean inspiratory carbon dioxide (ImCO2) while using fresh gas flow at 4, 3.5, 3, 2.5, 2, and 1.5 LPM. EtCO2 of 35-60 mmHg and ImCO2 of <6 mmHg were considered clinically acceptable. RESULTS: Thirty-five patients were enrolled in the present study Mean value (95% CI) of EtCO2, ImCO2 and fresh gas flow rate in group I were 42 +/- 3.2 (39.8, 44.2), 3 +/- 1.2 (2.2, 3.8) mmHg, and 1.7 +/- 0.6 (1.2, 2.1) LPM respectively. Mean value (95% CI) of EtCO2 ImCO2 and fresh gas flow rate in group II were 50 +/- 5.6 (47.2, 52.8), 3 +/- 0.9 (2.6, 3.4) mmHg, 2 +/- 0.4 (1.8, 2.2) LPM respectively. Mean value (95% CI) EtCO, ImCO2 and fresh gas flow rate in group III were 51 +/- 7.2 (46.7, 55.3), 2 +/- 1 (1.4, 2.6) mmHg, and 2 +/- 0.3 (1.8, 2.2) LPM respectively. No patients had serious complications in the present study. CONCLUSION: Baby EAR circuit can be made economically and used safelyfor general anesthesia with spontaneous breathing in pediatric patients who weighed 5-20 kg at optimal fresh gas flow rate of > or = 2.5 LPM

A clinical determination of optimal fresh gas flow in a baby EAR circuit.

OBJECTIVE: Baby EAR circuit is a new modified enclosed afferent reservoir anesthetic breathing system for pediatric patients. By following His Majesty the King of Thailand's self-sufficiency philosophy, the circuit is simple and made of low-cost and easy-to-find materials found in the operating room. This present study was to investigate clinical use of the circuit and to find the optimal fresh gas flow in clinical setting. MATERIAL AND METHOD: A prospective descriptive study was conducted in pediatric patients, weighed 5-20 kg, anesthetized for surgery. The Baby EAR breathing circuit was used for general anesthesia with endotracheal tube and control ventilation. Different fresh gas flow of 3, 2.5, 2 and 1.5 liter per minute (LPM) was used consecutively. The authors recorded end-tidal carbon dioxide (EtCO2) and mean inspiratory carbon dioxide (ImCO2) while using fresh gas flow at 3, 2.5, 2, and 1.5 LPM. EtCO2 of 35-45 mmHg and ImCO2 of < 6 mmHg were considered clinically acceptable. RESULTS: Fifty patients were enrolled. Mean value (95% CI) of EtCO2 at fresh gas flow rate of 1.5, 2, 2.5, and 3 LPM were 39.6 (39.2, 40.9), 36.7 (35.5, 37.8), 35.4 (34.3, 36.4), and 35.4 (34.3, 36.4) mmHg respectively. Mean value (95% CI) of ImCO2 at fresh gas flow rate of 1.5, 2, 2.5, and 3 LPM were 4.0 (3.0, 4.9), 2.4 (1.7, 3.0), 1.8 (0.9, 2.6), and 1.3 (0.9, 1.7) mmHg respectively. Percentage of patients (95% CI) who had clinically acceptable EtCO2 and ImCO2 at fresh gas flow rate of 1.5, 2, 2.5, and 3 LPM were 70% (56.2, 80.9), 92% (81.2, 96.8), 98% (89.5, 99.6), and 100% (92.9, 100) respectively. No patients had serious complications. CONCLUSION: Baby EAR circuit can be made economically and used safely for general anesthesia with control ventilation in pediatric patients weighing 5 to 20 kg at optimal fresh gas flow of 3 LPM.

A fatal adverse effect of cefazolin administration: severe brain edema in a patient with multiple meningiomas.

Cefazolin is commonly administered before surgery as a prophylactic antibiotic. Hypersensitivity to cefazolin is not uncommon, and the symptoms mostly include urticaria, skin reaction, diarrhea, vomiting, and transient neutropenia, which are rarely life threatening. We present a rare case of fatal cefazolin hypersensitivity in a female who was diagnosed with multiple meningiomas and scheduled for craniotomy and tumor removal. Immediately after cefazolin IV administration, the patient developed acute hypertensive crisis, which resolved within 10 minutes after the treatment. This was followed by unexplained metabolic acidosis. The patient then developed severe brain edema 100 minutes later. The patient had facial edema when her face was exposed for the next 30 minutes. A computed tomography scan revealed global brain edema with herniation. She was admitted to the intensive care unit for symptomatic treatment and died 10 days after surgery from multiorgan failure. The serum IgE level was very high (734 IU/mL). Single-dose administration of cefazolin for surgical prophylaxis may lead to rare, fatal adverse reaction. The warning signs are sudden, unexplained metabolic acidosis, hypertensive crisis, tachycardia, and facial angioedema predominating with or without cutaneous symptoms like urticaria.

Comparative study of minimal fresh gas flow used in Lack-Plus and Lack's circuit in spontaneously breathing anesthetized adults.

BACKGROUND: The Lack's circuit is a co-axial Mapleson A breathing system commonly used in spontaneously breathing anesthetized adults but still requires high fresh gas flow (FGF). The Lack-Plus circuit was invented with the advantage of lower FGF requirement. The authors compared the Lack-Plus and Lack's circuit for the minimal FGF requirement with no rebreathing in spontaneously breathing anesthetized adults. METHODS: This was a randomized crossover study. We enrolled 24 adult patients undergoing supine elective surgery, with a body mass index ≤30 kg/m2 and an American Society of Anesthesiologists physical status I-II. They were randomly allocated to group 1 (LP-L) starting with Lack-Plus then switching to Lack's circuit or group 2 (L-LP) (with the reverse pattern). After induction and intubation, anesthesia was maintained with 50% N2O/O2 and desflurane (4%-6%) plus fentanyl titration to maintain an optimal respiratory rate between 10 and 16/min. Starting with the first circuit, all the patients were spontaneously breathing with a FGF of 4 L/min for 10 min, gradually decreased by 0.5 L/min every 5 min until FGF was 2.5 L/min. End-tidal CO2, inspired minimum CO2 (ImCO2), mean arterial pressure, and oxygen saturation were recorded until rebreathing (ImCO2 >0 mmHg) occurred. The alternate anesthesia breathing circuit was used and the measurements were repeated. RESULTS: The respective minimal FGF at the point of rebreathing for the Lack-Plus and Lack's circuit was 2.7±0.8 and 3.3±0.5 L/min, respectively, p<0.001. At an FGF of 2.5 L/min, the respective ImCO2 was 1.5±2.0 and 4.2±2.6 mmHg, respectively, p<0.001. CONCLUSION: The Lack-Plus circuit can be used safely and effectively, and it requires less FGF than Lack's circuit in spontaneously breathing anesthetized adults.

Transdermal fentanyl patch for postoperative analgesia in total knee arthroplasty: a randomized double-blind controlled trial.

PURPOSE: To assess the efficacy of a transdermal fentanyl patch (TFP) (50 µg/hour) applied 10-12 hours before surgery versus placebo for postoperative pain control of total knee arthroplasty (TKA). MATERIALS AND METHODS: We enrolled 40 patients undergoing elective TKA under spinal anesthesia using isobaric or hyperbaric bupivacaine. Subjects were randomized to receive a TFP (Duragesic(®) 50 µg/hour) or placebo patch applied with a self-adhesive to the anterior chest wall 10-12 hours before spinal anesthesia. Every patient was given patient-controlled morphine for postoperative pain control. Patients were evaluated every 4 hours until 48 hours. RESULTS: Morphine consumption at 24 and 48 hours in the TFP group versus the placebo group was 15.40±12.65 and 24.90±20.11 mg versus 33.60±19.06 and 57.80±12.65 mg (P≤0.001). Numeric rating scale scores at rest and during movement over 48 hours were lower in the TFP group. Ambulation and nausea/vomiting scores were statistically greater, but not clinically significant in the TFP group. Sedation scores were low and not statistically significantly different between groups. There was no severe respiratory depression. CONCLUSION: TFP (50 µg/hour) applied 10-12 hours before surgery can effectively and safely decrease morphine consumption and pain scores during the first 48 hours after TKA surgery.

1-1-12 one-step wash-in scheme for desflurane-nitrous oxide low-flow anesthesia: rapid and predictable induction.

BACKGROUND: We propose a 1-1-12 wash-in scheme for desflurane-nitrous oxide (N2O) low-flow anesthesia. The objective of our study was to determine the time to achieve alveolar concentration of desflurane (FAD) at 1, 2, 3, 4, 5, and 6%. METHODS: We enrolled 106 patients scheduled for elective surgery under general anesthesia. After induction and intubation, wash-in was started with a fresh gas flow (FGF) of N2O : O2 1 : 1 L min(-1) and vaporizer concentration of desflurane (FD) of 12%. Ventilation was controlled to maintain PACO2 at 30-35 mmHg. RESULTS: The FAD rose rapidly from 0 to 4% in 2 min in a linear manner in 0.5 min increments. An FAD of 6% was achieved in 4 min in a linear fashion from FAD of 4% but in 1 min increments. An FAD of 1 to 6% occurred at 0.6, 1, 1.5, 2, 3, and 4 min. Heart rate during wash-in showed a statistically, albeit not clinically, significant pattern of increase. By contrast, blood pressure slightly decreased during this period. CONCLUSIONS: We developed a 1-1-12 wash-in scheme using a FGF of N2O : O2 1 : 1 L min(-1) and FD of 12% for desflurane-nitrous oxide low-flow anesthesia. A respective FAD of 1, 2, 3, 4, 5, and 6% can be expected at 0.6, 1, 1.5, 2, 3, and 4 min.