Anesthesia New Century-Optiflow in Anesthesia- You may use NMJB without Endotracheal Tube or LMA and only with Nasal Cannula
Anesthesia Department, Kuang Tien General Hospital, Taiwan
Submission: March 16, 2018; Published: March 23, 2018
*Corresponding author: Cheesang Ho, Anesthesia Department, Kuang Tien General Hospital, Anesthesia Department, Taipei Medical University, 117 Shatian Road Shalu District, Taichung City 43303, Taiwan, Tel: 937185868; Email: email@example.com
How to cite this article: Cheesang Ho. Anesthesia New Century-Optiflow in Anesthesia- You may use NMJB without Endotracheal Tube or LMA and only
with Nasal Cannula. J Anest & Inten Care Med. 2018; 6(2): 555682. DOI: 10.19080/JAICM.2018.06.555682
Optiflow was wide used in internal medicine and pediatric. In anesthesia, there were many paper in publish about high-flow nasal oxygen optimizes preoxygenation and apnea time compared with low-flow techniques, and improves carbon dioxide (CO2) clearance and enhanced apnea time, but no any paper to description using Optiflow in anesthesia. In this paper will be described how to use Optiflow in anesthesia and its principle and mechanism, benefits and limitation.
Keywords: Optiflow anesthesia; Low airway pressure; High flow; Nasal cannula
What is Optiflow? Optiflow is word optimal flow, which was provided by Fisher & Paykel Healthcare in 20 years ago. Optiflow device could provide ability to independently titrate FiO2 (up to 100%) and flow up to 60 L/min. In respiratory therapy, which was a revolutionary therapy and one ofthe most exciting developments since the introduction of noninvasive ventilation? In internal medicine, the physicists used this device to treat central sleep apnea and COPD, respiratory failure and heart failure patient instead of CPAP [1-4]. In recent years there were some publication about Optiflow could enhance the apnea time for intubation and also increased the outcome in postextubation . But there were no any publication about Optiflow in anesthesia. Does it could be used in anesthesia? That is a good question.
Everybody knows that the oxygen could not transfer to the brain directly, because of the brain was protected by the skin and the skull bone. And the oxygenation must be done by the respiration system. The mechanism of respiration was by diffusion and bulk flow. Every time, at rest breathing, approximately one
third of tidal volume is breathe in from the anatomical dead space. The anatomy dead space in adult is about 150 ml (2.2mLs/kg) , and the alveolar dead space  is sum of the volumes of those alveoli which have little or no blood flowing through their adjacent pulmonary capillaries, i.e., alveoli that are ventilated but not perfused, and where, as a result, no gas exchange can occur. Alveolar dead space is negligible in healthy individuals, but can increase dramatically in some lung diseases due to ventilation- perfusion mismatch. This was about 24ml. The diffusion, we can not to control it, but the rebreathing gas in dead space we could control. Normally, we need inspiration and expiration to reduce the dead CO2. But now we used high volume bulk flow, the dead space CO2 will be changed to be oxygen, a nearly 100% oxygen in dead space. Which significantly reduce CO2 rebreathing due to HFNC, approximately 1.8 cc/second increased in clearance for every 1.0 L/min increase in flow? Because of that, we may use neuromuscular junction blocker (NMJB) without endotracheal tube or LMA and only with nasal cannula (Figures 1-3).
In Fisher & Paykel Healthcare, they provided two types of humidifier, one is home humidification and the other is hospital humidification. In hospital humidification, there were only MR810 Heated Humidifier and MR850 Heated Humidifier could be used in anesthesia. It was because of those model could provide 100% oxygen, invasive and noninvasive ventilation and the others were not.
Apneic oxygenation using low-flow oxygen is laminar flow, and the apneic oxygenation using high-flow oxygen is turbulent flow, so that the dead space CO2 could be washout . For easily understand, I give a simple study to explain. When you have a bucket of sea water, you used tap water to dilution it (Figure 3). Even you used low flow with long time or used high flow in short time, the sea water must be dilution to be nearly to tap water. So that, when you used high flow the dead space CO2 could nearly totally wash out.
In the dead space CO2 was exchanged by oxygen, every inspiration only with the minimal CO2. So that, even the lung no ventilation, the diffusion was going on, and the patient without any hypoxia. This phenomenon you may use brain function monitor (Production by Masimo Company) to monitoring the SpO2, which could monitoring SpO2 from 100% to 400%.
We must remember that, when you used Optiflow in anesthesia, you could not use inhalation agents, because the flow is too high, if you use that, the outcome is very horrible. And the concentration of inhalation agents you could not easily to control. So, you only could use TIVA/TCI for hypnosis and analgesia. Before induction, you may give the flow about 30L/min for 10 minutes; then you may run TCI. When the patient in sleep, you may adjust
the oxygen flow to be 70L/min. At that time you may use NMJB or not. If you do not used NMJB, the flow up to 50/min is enough.
During in spontaneous breathing, the patent with mild acidemia and doesn't need to treat. When in nonspontaneous breathing, the acidemia is worst then in spontaneous breathing patent. Sometimes you may treat with them.
Patients who cannot maintain a patent airway. Do not have spontaneous respiratory effort. Head and/or neck injury which has not yet been stabilized. Active hemorrhage with hemodynamic instability. Oral surgery needs electric cauterization.