Cook Medical’s Doppler Blood Flow Monitor is used for monitoring blood flow in vessels intraoperatively—for flap monitoring and to monitor vessels following reconstructive microvascular procedures and reimplantations. The monitor is designed to provide audible (primary) and visual (secondary) feedback of blood flow when connected to Cook-Swartz Doppler Probes and extension cables. Blood flow can be monitored continuously or periodically as required.
Watch the five instructional videos below to learn more about the Doppler Blood Flow Monitor.
- Video 1: Surgical placement
- Video 2: Intraoperative troubleshooting
- Video 3: Probe removal
- Video 4: Using the monitor
- Video 5: Postoperative troubleshooting
Video 1: Surgical placement
Watch a surgeon place a probe, and learn how to best position the cuff.
[Transcript] Upon completion of the surgical anastomosis, the Cook-Swartz Doppler Probe is placed around the vessel, with the probe crystal situated as far as possible from adjacent vessels, to limit the reception of flow signals from them. Many physicians have noted that it is preferable to monitor the venous blood flow. It has been demonstrated that monitoring the vein assures that blood is flowing through both the artery and the vein. Some physicians prefer to monitor the artery, or both vessels simultaneously.
Proper placement of the cuff depends on the type of procedure being done and surgeon preference. Some surgeons have suggested that during an end-to-side anastomosis, the cuff be placed proximal to the anastomosis in order to get a signal most indicative of profusion of the free flap. During an end-to-end anastomosis, some surgeons suggest the cuff be placed distal to the anastomosis.
Trim the curved silicone cuff to accommodate the vessel size. The cuff length should allow close approximation of the probe crystal to the vascular adventitia. Position the silicone cuff around the targeted blood vessel, ensuring that the probe crystal is directed toward the targeted vessel. Secure the free ends of the silicone cuff together using appropriate sutures or a clip to maintain cuff position.
Plug the silver end of the extension cable into either of the two channels. Attach the red end of the probe to the red end of the extension cable, aligning the black dots. Stabilise the location of the probe by suturing the braided wire adjacent to the incision site, leaving some slack to alleviate tension on the cuff. Enough wire should be provided so that there is no tension on the vascular anastomosis. The retention tab may be placed over the braided wire and sutured or taped to the skin to provide additional strain relief.
Video 2: Intraoperative troubleshooting
Make sure the probe can pick up signals from the patient’s blood vessel.
[Transcript] Once the monitor has been turned on, the blood flow should be heard. The LED light indicators represent the relative velocity of the blood cells passing by and within range of the probe crystal. The higher the velocity the more of the indicators are illuminated. If a signal is not heard, the following steps should be taken: Irrigate the probe with saline where it wraps around the blood vessel adventitia. An audible signal, the primary indicator, and visual signal on the LED display, the secondary indicator, verify that the device is functioning properly.
‘If you irrigate and you can hear that signal, that means the probe is working.’ (Dr Michael L. Gimbel, University of Pittsburgh Physicians Aesthetic Plastic Surgery Center, Division of Plastic and Reconstructive Surgery.)
The probe could be too loose. This can be confirmed by pressing or tapping on the probe to check its snugness. Tap or press near the location of the end of the probe, being careful not to put tension on the probe wire to avoid potential dislodgement of the probe. A correctly functioning probe should detect this action, and the monitor should deliver both an audio and visual signal. Also, a patient’s movement can lead to audible and visual signal responses from the blood flow monitor, indicating that the probe is working. If the probe still does not produce an audible signal, the probe is either malfunctioning or has been dislodged. Blood flow has been disrupted during patient repositioning, or blood flow has become restricted.
After it has been verified that the probe is functioning properly, the incision site should be closed using standard techniques. It is helpful to listen to the blood flow from the monitor during the flap inset and wound closure. These manoeuvres will often cause compression on the vascular pedicle and the Cook Doppler Blood Flow Monitor can help detect this compression.
‘The probe is really marketed for a postoperative monitoring of flaps. I find it very useful intraoperatively as well because, maybe less so for breast flaps, but even sometimes for breast flaps, but more so for extremity flaps when you are suturing the flap down. Often it can be tight and there’s not a lot of room for the pedicle to distribute itself and it can become kinked or it can become compressed, and you don’t know that once the flap is inset. You don’t know that immediately unless you have something that’s actually listening to the vessels.’ (Dr Gimbel)
Video 3: Probe removal
You only need to tug lightly on the probe to detach it from the patient’s blood vessel.
[Transcript] After the physician has determined the flap is healing well and blood flow has been established, the crystal must be removed by the following steps:
Remove sutures or tape from the wire outside the wound, and from the retention tabs.
Tug gently on the wire near the crystal to disengage it from the cuff. Only one-tenth of a pound of pressure is needed to remove the crystal from the cuff.
Leave the silicone cuff. It remains permanently in place around the vessel.
Alternative methods of discontinuing use of the probe, such as cutting the wire and tucking it into the wound, are not recommended, and are contrary to approved instructions for use.
Video 4: Using the monitor
Learn about the controls and functions of the Doppler Blood Flow Monitor.
[Transcript] The Doppler Blood Flow Monitoring System has been designed for ease of use. The power switch turns the unit on and off. The low-battery LED light will illuminate when the battery should be charged. The monitor operates on an internal lithium ion rechargeable battery, which allows long-term monitoring and battery conservation. Attach the supply charger to the back of the unit and charge the internal battery until the indicator on the top of the charger illuminates green. It is important to use the charger labelled ‘Doppler Blood Flow Monitor Battery Charger.’ Other chargers could potentially damage the monitor.
The volume control adjusts the loudness of the audio output. The LED lights will illuminate as the volume is raised or lowered. The blood flow indication lights allow visual blood flow confirmation, although sound remains the primary indicator.
Select the desired channel by pressing the ‘Channel’ button to ensure that the LED that corresponds to the desired channel is illuminated. The two channels allow the connection of either one or two probes to the monitor via the extension cable. The ‘Test’ button will produce a steady tone indicating that the unit is functioning properly.
The integrated pole mount allows for easy placement on a bedside pole. When securing the Cook Doppler Blood Flow Monitor onto the pole, first, ensure the flat surface is flush against the pole. Then, secure the monitor by turning the screw clockwise. The red dots on the monitor’s channel and the silver end of the extension cable must be aligned. Press the end of the extension cable into the channel until it is lodged firmly in place. When connecting the probe to the extension cable, attach the red end of the probe to the red end of the extension cable, aligning the black dots.
The Cook Doppler Blood Flow Monitoring System may be cleaned with a mild detergent or isopropyl alcohol. Prior to cleaning, make sure that the monitor is not connected to a power supply. Do not immerse the unit in a solution or allow a solution to enter the connector inputs, outputs, or speaker grill.
The Cook Doppler Blood Flow Monitoring System gives you a way to directly monitor the target vessel. It is implantable. The probe attaches directly to the target vessel, providing a precise means of monitoring blood flow without interference from neighboring vessels or tissues. It is continuous. This continuous monitoring allows loss of patency or thrombosis to be detected immediately. It is clear, with both audio and visual confirmation. The blood flow is easy for both the clinician and the healthcare staff to monitor.
Video 5: Postoperative troubleshooting
If you don’t see or hear a signal from the monitor after the surgery, do some quick troubleshooting to rule out mechanical error.
[Transcript] If no audio or visual signals are identified, the following steps can be taken:
Test the probe function by pressing or palpating near the probe’s site for better crystal contact, or consider repositioning the patient. With the monitor turned on, press the ‘Test’ button. A tone should verify that the monitor’s internal circuitry is functioning properly. The combined channel and cable verifier may then be used.
To test a channel, plug the silver end of the verifier into a channel on the monitor. Rub the clear resin surface until the monitor makes a sound. If the monitor doesn’t make a sound, there is a problem with the channel.
To test the extension cable, plug the extension cable into a channel on the monitor. Plug the red end of the verifier into the extension cable. Rub the resin surface until the monitor makes a sound. If the monitor doesn’t make a sound, there is a problem with the cable.
If the unit is functioning correctly and the blood flow cannot be heard, contact the physician immediately.
Dr Gimbel is an independent physician with no financial ties to Cook Medical.