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The anaesthetic machine
Published in Daniel Cottle, Shondipon Laha, Peter Nightingale, Anaesthetics for Junior Doctors and Allied Professionals, 2018
The final fresh gas flow/vapour mix exits the anaesthetic machine via the common gas outlet; it is here that the O2 analyser is situated (before the gas mixture enters the patient). The pressure of the gas is now at approximately atmospheric pressure, with most of the drop from the pipeline pressures having occurred across the rotameters.
Paper 5 Answers
Published in James Day, Amy Thomson, Tamsin McAllister, Nawal Bahal, Get Through, 2014
James Day, Amy Thomson, Tamsin McAllister, Nawal Bahal
The TEC 6 desflurane vaporizer is an example of a measured flow vaporizer. The principle of this type of vaporizer is that there is a separate stream of anaesthetic vapour that is added to the fresh gas flow. The vaporizer must measure and adjust for changes in the fresh gas flow. To overcome the physical properties of desflurane, the TEC 6 vaporizer utilizes an electrically powered heating element to heat the desflurane to 39°C. This raises its SVP to 194 kPa. To provide accurate agent concentrations, the amount of agent added is proportional to the fresh gas flow. This is achieved by using a differential pressure transducer. There is a flow restriction in the fresh gas flow. Any increase in flow will produce a back pressure, which acts on the differential pressure transducer. This then acts on a variable resistor at the agent outflow to increase agent flow in-line with the fresh gas flow. Vice versa is also true.
Anesthesia Equipment
Published in Michele Barletta, Jane Quandt, Rachel Reed, Equine Anesthesia and Pain Management, 2023
Rachel Reed, Stephanie Kleine, Michele Barletta
There are several factors that affect delivered tidal volume in anesthetic ventilators: Fresh Gas Flow: Fresh gas continues to flow into the anesthesia circuit throughout the inspiratory phase of ventilation. Most veterinary ventilators do not account for this additional volume contribution to the patient’s tidal volume.Compliance and Compression Volumes: Hoses used in breathing circuits have varying degrees of compliance. Stretch of these hoses during the inspiratory phase of ventilation can lead to changes in tidal volume delivered to the patient. Therefore, the volume of gas administered as indicated by the compression of the ventilator bellows is not entirely accurate, as some volume is lost to expansion of the airway hose.Leaks: Any leaks within the anesthesia circuit will impact the delivered tidal volume as airway gas is lost through the leak during positive pressure inspiration. Depending on the bellows style, detection of a large leak while the patient is anesthetized can be quite easy or not obvious at all. Ascending bellows will collapse when there is a large leak in the circuit, making the presence of a leak obvious to the anesthetist. Conversely, descending bellows can entrain room air or driving gas during the expiratory phase, making detection of the large leak difficult. This poses the additional hazard that entrainment of room air or driving gas can result in lower than expected inspired inhalant anesthetic concentrations and lower than expected inspired oxygen concentration in the case of room air entrainment.
The Comparison of Postoperative Analgesic Efficacy of Ultrasound-Guided Paravertebral Block and Mid-Point Transverse Process Pleura Block in Mastectomy Surgeries: A Randomized Study
Published in Journal of Investigative Surgery, 2022
Agâh Abdullah Kahramanlar, Mehmet Aksoy, Ilker Ince, Aysenur Dostbıl, Erdem Karadenız
Routine general anesthesia protocol was performed using 2–3 mg/kg IV propofol, 0.6 mg/kg IV rocuronium, and 2 µg/kg IV fentanyl. Anesthesia was maintained with desflurane, a fresh gas flow of 3 L/min, and a nitrous oxide mixed with oxygen in a 2:1 ratio. During surgery, the patient’s systolic, diastolic and average artery blood pressures and oxygen saturation values were recorded in the 5th, 10th, 15th, 20th, 35th, and 50th minutes, and postoperative 1st and 2nd hours. At the end of the operation, neuromuscular block antagonization was performed using sugammadex (4 mg/kg). All patients were extubated and taken to the postanesthetic care unit (PACU). Patients with a modified Aldrete score ≥9 were transferred to the clinic. Intravenous 1 g of paracetamol was administered to all patients postoperatively and the same dose was repeated every 6 hours. Intravenous 8 mg of ondansetron was administered to all patients, for the prevention of nausea and vomiting. Intravenous 6 mg of ephedrine was used to treat hypotension (a 20% decrease in systolic blood pressure compared to baseline values) and IV 1 mg of atropine was given in case of bradycardia (the heart rate < 45 beats/minute) during the operation. Nausea and vomiting were treated with an IV of 10 mg of metoclopramide.
Reflection efficiencies of AnaConDa-S and AnaConDa-100 for isoflurane under dry laboratory and simulated clinical conditions: a bench study using a test lung
Published in Expert Review of Medical Devices, 2021
Azzeddine Kermad, Jacques Speltz, Philipp Daume, Thomas Volk, Andreas Meiser
The disadvantage of a lower reflection efficiency of ACD-50 must be weighed against its smaller carbon dioxide retention. Due to its smaller size, volumetric dead space of ACD-50 is smaller by 50 mL, and it also reflects less carbon dioxide leading to 15 ml reduced reflective dead space compared to ACD-100 [28–31]. In a clinical study, 10 spontaneously breathing patients reduced their tidal volume by 66 ml on average when switched from ACD-100 to ACD-50 with unchanged ventilator settings, opioid, and isoflurane infusion rates [32]. This is beneficial: First, a reduced tidal volume is crucial for lung protective ventilation. Second, a reduction in tidal volume decreases V-exh and thus increases reflection efficiency according to our findings (Figure 4). Third, a reduced minute ventilation decreases losses of isoflurane through the reflector even at the same reflection efficiency. In fact, in the before-mentioned clinical study [32], end-tidal isoflurane concentrations only decreased in two patients with V-exh higher than 5 mL. ACD-50 has also been used in the operating room and showed reduced anesthetic consumption compared to conventional circle systems operated with low- and even minimal fresh gas flow [33].
Effects of automatic gas control on sevoflurane gas monitor and recovery during pancreatico-duodenectomy operation: prospective randomized study
Published in Egyptian Journal of Anaesthesia, 2023
Eman Sayed Ibrahim, Sally Waheed ELkhadry
AGC is prepared to attain the aimed end-tidal anesthetic agent you determine, with the desired speed ranging from 3 to 15 minutes. The risk of hypoxia is also reduced as FLOW-I’s unique active O2 guard functions are designed to reduce the risk of hypoxia [2]. The need for repeated manual control of the anesthetic agent, fresh gas flow (FGF), and O2 was reduced as AGC automatically regulates the FGF and anesthetic agent supply according to the needed end-tidal anesthetic agent (EtAA) [3].