Ayako Ohashi

Evaluation of Differences between PaCO2 and ETCO2 by Age as Measured during General Anesthesia with Patients in a Supine Position

Objective. The aim of this study was to evaluate the arterial to end-tidal partial pressure gradient of carbon dioxide according to age in the supine position during general anesthesia. Methods. From January 2001 to December 2013, we evaluated 596 patients aged ≥16 years who underwent general anesthesia in the supine position. The anesthetic charts of these 596 patients, all classified as American Society of Anesthesiologists physical status I or II, were retrospectively reviewed to investigate the accuracy of PaCO2 and ETCO2. Results. The a-ETCO2 was  mmHg for patients aged 16 to <65 years and  mmHg for patients ≥65 years. The a-ETCO2 was  mmHg for patients aged 16 to 25 years,  mmHg for patients aged 26 to 35 years,  mmHg for patients aged 36 to 45 years,  mmHg for patients aged 46 to 55 years,  mmHg for patients aged 56 to 64 years,  mmHg for patients aged 65 to 74 years, and  mmHg for patients aged 75 to 84 years. Conclusion. The arterial to end-tidal partial pressure gradient of carbon dioxide tended to increase with increasing age.

Changes in Intra-cerebral Oxygenation During Intravenous and Inhalational Sedation: A Original Research

Background: Although sedatives such as midazolam or nitrous oxide (N2O) are administered to dental patients, the effects of these drugs on intra-cerebral oxygenation are not well-known. Aims: We investigated the effects of intravenous midazolam or inhalational N2O on intra-cerebral oxygenation using near-infrared spectroscopy. Setting and Design: University hospital, prospective. Materials and Methods: During intravenous sedation, volunteers received supplemental oxygen through nasal cannula at 3 L/min for 10 min (control group). Midazolam (0.05 mg/kg) was then injected intravenously with flumazenil (20 mg) injected 30 min later. In the inhalational sedation study, volunteers lay quietly for 10 min receiving 100% oxygen, then received N2O via nasal mask at concentrations of 10%, 20%, and 25% for 5 min; 30% for 20 min; and supplemental oxygen at 100% for 15 min after N2O was discontinued. Statistical Analysis: Intra-group comparisons were made using one-way analysis of variance for repeated measures followed by Dunnett’s test for multiple comparisons. Differences were considered statistically significant at P < 0.05. Results: During intravenous sedation, oxyhemoglobin increased 10 min after midazolam administration, and total hemoglobin increased slightly until 20 min after flumazenil administration, followed by a decrease. During inhalational sedation, oxyhemoglobin increased until 5 min after starting N2O, and total hemoglobin increased until 5 min after starting N2O, followed by a decrease. Conclusions: Midazolam and N2O influenced intra-cerebral oxygenation during intravenous or inhalational sedation. Cerebral blood flow increased with intravenous sedation when midazolam was administered once at a dose of 0.05 mg/kg and with inhalational sedation when N2O was supplied at a concentration of 25-30%.

Changes in Intra-cerebral Environment in Patients Undergoing Tracheotomy: An Original Research

Background and Objectives: Microvascular flap reconstruction has recently proven to be very reliable for repairing defects in the oral and maxillofacial cavity defects. Such patients often require a tracheotomy to stay in the intensive care unit post-operatively. Although tracheotomy is usually performed after oral intubation, details of the intra-cerebral oxygenation environment during tracheotomy are unclear. Using near-infrared spectroscopy, we investigated the changes in intra-cerebral oxygenation during exchange from oral to tracheal intubation in patients undergoing tracheotomy. Materials and Methods: We evaluated eight patients with an American Society of Anesthesiologists physical Status of I or II who were scheduled to undergo tracheotomy. Changes in the intra-cerebral levels of oxyhemoglobin (oxy-Hb), deoxyhemoglobin (deoxy-Hb), total hemoglobin (total-Hb), and cytochrome oxidase (cyt) were monitored during tracheotomy. Results: Blood pressure increased rapidly during exchange from an oral to tracheal intubation tube. The maximum oxy-Hb level (3.5 ± 2.4 nmol/L) occurred 5 min after the exchange, the maximum deoxy-Hb level (0.8 ± 1.0 nmol/L) occurred 5 min after the exchange, the maximum total-Hb level (1.8 ± 2.2 nmol/L) occurred 5 min after the exchange, and the minimum cyt level (−0.5 ± 0.2 nmol/L) occurred 7 min after the start of the operation. Conclusions: The intra-cerebral oxy-Hb and total-Hb levels increased after exchange from an oral to tracheal intubation tube during tracheotomy, and these hemodynamic changes attenuated the cerebral blood flow.

Severe Bradycardia Possibly due to a Local Anesthetic Oral Mucosal Injection during General Anesthesia

Local anesthesia may induce systemic complications leading to parasympathetic activity leading to bradycardia and hypotension. We report a case of a 50-year-old man undergoing dental surgery under general anesthesia who experienced severe bradycardia and hypotension after local anesthesia infiltration. Concerns regarding the utilization of a relatively large lumen injection needle for local anesthesia during general anesthesia are discussed.