Cardiac arrest is a sudden stop in heart function. This is noticeable when the EKG flatlines. Upon cardiac arrest, vitals drop to and stay capped at 10, and steadily drop (except in Trauma Team, where vitals will start dropping from current vitals). It is treated with the defibrillator or with a heart massage. In some cases, defibrillation is impossible due to the presence of foreign objects in the heart, necessitating the continuation of the operation without it. In Under the Knife, vitals are kept at 1, and the player has a time limit of 1 minute to restart the heart with a heart massage.
In some operations, the EKG shows abnormalities before the patient undergoes cardiac arrest. This is sometimes accompanied with the vitals gauge turning yellow regardless of the vitals count. During this time the player is supposed to suspend the treatment and wait for the condition to stabilize or the patient to flatline, though the player can still operate normally during this time. If the patient's condition worsen, doing anything before the patient flatlines results in a Miss.
Trauma Team opts to show the EKG abnormalities by displaying it across the screen from time to time. Attempting to treat the patient after it shows results in a Miss, and the flatlining display will call for immediate resuscitation.
Cardiac arrest is treated by restarting the heart, usually by using a defibrillator. In Under the Knife 2, this is done by sliding the paddles into position with the stylus, then holding the stylus down to charge the defibrillator. In the Wii games, the defibrillator is positioned by moving the Wiimote and Nunchuck towards the screen. The defibrillator's charge meter will oscillate about the gauge, and pushing both the B and Z buttons together will begin a defibrillation attempt.
On the defibrillator's charge gauge is a marked area, with a small green area and a slightly larger grey area. Hitting the green mark will instantly defibrillate the patient, while hitting the grey area will require a second attempt. Note that in some cases the required voltage is different due to the patient being different from a normal adult.
Heart Massage/Cardiopulmonary ResuscitationEdit
In Under the Knife, Angie will automatically defibrillate the patient when abnormal heart patterns occur, and then the player has to follow up with a heart massage. First, antibiotic gel is applied over the specified area. Then, the oscillating dark area is followed with the hands tool selected. If sufficient gel is applied a Cool will be awarded. Otherwise, the area will turn grey midway during the massage, and only a Good will be awarded. Other wounds can be treated in the meantime, provided the player is fast enough to finish the massage within the one minute limit. Once the treatment is complete, the time limit is reset to the time before cardiac arrest began, and vitals are restored to their previous level.
In subsequent games, the heart massage is used when it is impractical to use the defibrillator. Two guides will appear, with one slowly shrinking towards the center of the screen. When both guides overlap, heart massage can be performed either by pressing both the A and B buttons on the Wiimote or tapping the stylus in the center of the screen. The timing will determine how many pulses are needed to restart the heart - usually about 5 to 10 are needed.
In Trauma Teams First Response section, CPR is given through chest compressions. There are two ways in which this can be done. A guide will appear, and following the guide's timing, the Wiimote needs to be swung down to perform a chest compression. Another way this is done is by holding the A button on the Wiimote and swinging it down, delivering a powerful blow that may restart the patient's heart.
The games' portrayal of cardiac arrest treatment is not completely accurate. Defibrillation is effective only for certain heart rhythms, namely ventricular fibrillation or pulseless ventricular tachycardia, rather than asystole or pulseless electrical activity. In real life, the defibrillator is used on abnormal heart patterns, rather than when the patients flatline. If they do flatline, CPR is performed to restart the heart.