ONLINE COMMENTARY TO ACCOMPANY OR FIRE PREVENTION VIDEO
The most notable finding when cases of operating room fires are reviewed is that most if not all are preventable! This video is intended to promote the best practices known to prevent the potentially devastating complication of a fire in the operating room. Each member of the operating room care team has a role to play in preventing operating room fires. The following commentary is intended to put the recommendations in the video into the context of current practice.
FOR THE ANESTHESIA PROFESSIONAL (prepared by Drs. Jeffrey M. Feldman and Robert K. Stoelting)
Minimizing or eliminating enriched oxygen delivery is fundamental to preventing operating room fires. An increased oxygen concentration in the surgical field is either a direct cause or a significant factor in many operating room fires – particularly procedures involving the head, neck, and upper chest.
The recommendation to eliminate open delivery of oxygen when sedating patients is the most striking practice change advocated in the fire prevention video. This is particularly a consideration for anesthesia professionals since they typically control oxygen administration. For most anesthesia professionals, oxygen administration by nasal cannula or mask (open oxygen delivery) is routine when providing sedation, and is a fundamental strategy for preventing hypoxemia. The recommendations in the video can help the anesthesia professional balance the risks and benefits of oxygen delivery for the individual patient. For patients in whom an increased oxygen concentration cannot be avoided, the video describes strategies that can minimize the risk of an operating room fire.
The following sections address frequently asked questions about the relationship between supplemental oxygen delivery and fire safety
Does the Patient Require Supplemental Oxygen?
This is the first question that the anesthesia professional should consider when developing a plan to minimize the risk of fire. The answer to this question will be based upon an understanding of the patient’s underlying pulmonary function and the depth of sedation that will be required to facilitate the surgical procedure. Patients who are oxygen dependent and have reduced oxyhemoglobin saturation while breathing room air are not candidates for sedation without supplemental oxygen. For such patients, safe care usually requires control of the airway or careful control of oxygen concentration in the surgical field (see below). For patients with normal pulmonary function, it may be possible to administer sedatives and narcotics without administering supplemental oxygen, depending upon the amount and type of medications that are used.
How can I accomplish room air sedation safely?
Safe room air sedation can be accomplished by selecting patients with normal pulmonary function, by administering sedatives and narcotics carefully, and by monitoring oxyhemoglobin saturation continuously.
Room air sedation is most likely to be successful if the surgical procedure is not very painful, or if local anesthetics can be used to reduce or eliminate painful stimulation. In such cases, patient comfort can be assured by titrating sedative medications and opioids in a manner that minimizes the risk of respiratory depression. As surgical stimulation becomes more painful, it becomes increasingly difficult to keep the patient still and comfortable without using doses of sedatives and opioids that lead to respiratory depression and create a need for supplemental oxygen and/or assisted ventilation. Patients who are especially anxious may require larger doses of sedative medications, resulting in respiratory depression and the need for supplemental oxygen and/or assisted ventilation.
Sedatives and opioids should be selected and used in a way that minimizes the risk of respiratory depression. Local anesthetics should be used as effectively as possible to avoid the unnecessary use of opioids. Drugs should be given by incremental titration, allowing sufficient time between doses to assess and manage drug effects before administering additional medication. Careful titration may increase the time needed to prepare the patient for the start of the procedure. Production pressure should not be the reason for hasty bolus administration that results in the need for oxygen administration and an increased risk of fire.
Oxyhemoglobin saturation monitoring by continuous pulse oximetry is essential to safe patient care. However, a saturation reading of 100% is not always necessary. Drug effects that lead to mild respiratory depression with a resulting but stable decrease in saturation as low as 92% may be consistent with safe care. Saturation values of 90% or less are usually undesirable because the steep portion of the oxyhemoglobin dissociation curve puts the patient at risk for rapid desaturation. Assuring continuous pulse oximetry monitoring requires attention to probe placement, including minimizing patient movement at the probe site and possibly insulating the probe from ambient light. If pulse oximeter measurement becomes unreliable during sedation, the procedure should stop until reliable measurement can be restored.
If room air sedation cannot be accomplished, is tracheal intubation necessary?
The most important anesthesia strategy for preventing operating room fires is to minimize the risk that an enriched oxygen concentration will be present at the source of heat (e.g. electrosurgical cautery or laser). If an oxygen concentration greater than 30% is required to prevent hypoxemia during sedation, then controlling the patient’s airway should be strongly considered – especially for procedures around the head, neck and chest. Tracheal intubation is a reliable method for confining an enriched oxygen concentration to the breathing circuit and the lungs. A laryngeal mask airway can also be effective for this purpose, but may not be as reliable as tracheal intubation. Other strategies that minimize the risk of an enriched oxygen concentration in the surgical field include open draping (wide exposure of the surgical site to the atmosphere) and blowing air over the patient’s face to wash out extra oxygen. Open draping and blowing air are not as reliable as tracheal intubation or a laryngeal mask airway because oxygen concentration cannot be measured routinely at the surgical site; thus, it is not possible to make a reliable decision that oxygen concentration is as low as desired before the heat source is activated.
When using open oxygen delivery, can I prevent operating room fires by carefully controlling the oxygen concentration delivered to the patient?
Rapid and widespread propagation of fire – “flash fire” – is minimized if oxygen concentration is less than 30%. The video describes several methods for the open delivery of oxygen at concentrations of 30% or less. These methods have advantages and disadvantages, and may not be easy to implement in some anesthesia locations. Table 1 outlines the five basic options for controlling oxygen concentration in an open system. Table 2 shows flows of oxygen and air that produce a gas blend with an oxygen concentration of 30%.
Several points merit emphasis. In general, the auxiliary flowmeter on the anesthesia machine is only capable of delivering 100% oxygen; it should not be used for open delivery of a controlled oxygen concentrations of 30% or less. An exception is the AS3000 (Mindray Datascope Corporation., Mahwah, NJ) which is available with a flowmeter for blending oxygen and air to deliver an oxygen concentration from 21% to 100%. If open delivery of a controlled oxygen concentration of 30% or less is desired, it is best to deliver this concentration from the start. If the delivered oxygen concentration is reduced to 30% at some time after a higher concentration of oxygen has been started, a higher-than-desired concentration of oxygen may persist for a time at the surgical site or under the drapes.
Table 1: Methods for controlling the delivered oxygen concentration through an open delivery system
| Option | Pros | Cons | How to Use |
| Direct connection to common gas outlet (CGO) |
|
|
|
| Anesthesia breathing circuit |
|
|
|
| Oxygen/Air Blender |
|
|
|
| Venturi system |
|
|
|
| Oxygen and Air flowmeters connected to auxiliary gas outlet |
|
|
|
Table 2: Oxygen flowmeter setting when mixing with air to achieve an oxygen concentration of 30%
| Total Flow (L/min) |
Air Flow (L/min) |
Oxygen Flow (L/min) |
|
1 |
0.84 |
0.16 |
|
2 |
1.69 |
0.31 |
|
3 |
2.53 |
0.47 |
|
4 |
3.38 |
0.62 |
NOTE: The total oxygen flow is significantly less than 1 L/min in all cases. Note that IT IS VERY EASY TO DELIVER TOO MUCH OXYGEN, THEREBY LEADING TO AN OXYGEN CONCENTRATION EXCEEDING 30%. Lower oxygen flows and higher air flows will result in lower oxygen concentrations.
Jeffrey M. Feldman, MD, MSE
Division Chief, General Anesthesia
Children’s Hospital of Philadelphia
Robert K. Stoelting, MD
President
Anesthesia Patient Safety Foundation