Archive for February 2011
Emergency medical technicians (EMTs) training is designed to teach individuals how to provide medical aid to people in need and are first responders in most medical emergencies. The responsibilities of an EMT to provide medical care, treatment or transportation can only be performed with the consent of the patient, except under certain conditions.
Expressed consent is one of the ways a patient can show their willingness to receive help. This occurs when a patient directly agrees to accept treatment. There are two criteria that must be followed for this form of consent to be legal. First, the patient must be of legal age and able to make rational decisions. Legal age can differ from state to state. An EMT should know what the legal age is in the state they work in. Besides being the legal age, a patient must be responsive, mentally competent, and aware of the risks associated with treatment or lack of treatment. Secondly, an EMT should advise the patient on all of the steps of the procedures that will be preformed and any risks that are associated with those procedures. Providing the patient with these criteria helps the patient to make an informed decision.
Implied consent can be assumed when a patient is not responsive and is suffering from a life-threatening or disabling injury or condition. In this instance, it is assumed that if the patient were responsive that he/she would want to receive treatment and would give expressed consent if they were able to. This type of consent often occurs with patients that are mentally, physically or emotionally unable to provide expressed consent.
Heart beats come from within the heart. The sinoatrial node (SA) located in the right atrium of the heart is responsible for generating each heart beat. How those beats are modulated is dependent on the brain and two types of control fibers- the parasympathetic and sympathetic control fibers. These different fibers can change the strength and timing of the heartbeat at different times of physical or emotional stress. Both of these fibers allow the brain to alter the heart’s rate and strength by sending impulses along sympathetic or parasympathetic nerve fibers.
Parasympathetic activity slows the rate of automatic sinoatrial impulses. This reduction, causes a decreased heart rate. Sympathetic activity often occurs during exercise and results in the sympathetic fibers releasing noradrenaline, which speeds up sinoatrial nodal impulse generation. The ventricles become excited because electrical conduction through the artioventricular node increases causing the heat to beat more often.
An electrocardiogram (ECG) is an instrument that is able to detect the electrical events that occur during a single heartbeat. The first event that an ECG identifies during a heart beat is the excitation of atrial tissue. This is called a ‘P wave’ on an ECG. After this initial electrical excitation in the atrial tissue an atrial contraction occurs and the electrical energy travels through the atrioventricular node (AV). The ventricular tissue is the next to become excited and is termed the ‘QRS’ complex of the ECG. This tissue usually remains excited for 0.2 -0.3 seconds. The recovery from the excitement is valued as the ‘T wave’ of the ECG.
ECG recording can provide valuable information on the potential range of conditions that can be involved with abnormal heartbeats. Many conditions produce characteristic alterations with specific ECG profiles.
The heartbeat of a heart is an action that originates from within the heart and is not dependant on impulses from the brain. This is an amazing feature of the heart because should the heart be removed from the body, it is still able to beat for long periods of time as long as it is bathed in a solution of vital nutrients. Because heartbeat is not dependant on brain impulses, a person can be considered brain dead and still have a working beating heart. While studying how to become a paramedic, you will learn all about the heart and its basic functions.
The sinoatrial node is a small areas of tissue located in the right atrium of the heart. This node contains specialized cells that have electrical properties which allow them to actually create sparks of electricity that initiate each heartbeat. The muscles of the heart are connected in a manner that allows the electrical impulses generated by the sinoatrial node to pass rapidly from cell to cell. This creates a wave of current that spread across both atria leading to a synchronized contraction of the atria which causes the blood in these chambers to be pushed into the lower chambers of the heart, called the ventricles.
These same electrical signals also make their way to the ventricles but must first pass through another node called the atrioventricular node (AV). The AV node delays the passage of impulse for approximately 0.1 of a second, at resting heart rates. This delay is important because it allows the ventricles to receive the blood that is being pumped into them from the upper chambers during a contraction, before pumping the blood into the circulation.
The adult human heart is an amazing muscle that beats over 100,000 times and pumps approximately 8,000 liters of blood in a 24-hour period. Unlike other muscles in the body, the amazing heart never rests. Should it ever stop or take a break, the human body would completely shut down and die. It is amazing to consider all that the heart does unceasingly every day.
There are two vital tasks the heart is responsible for performing. The first task is propelling oxygen rich blood to all the parts of the body. The second task is to circulate deoxygenated blood from all over the body and back to the lungs where it will be reoxygenated.
The dual responsibility of the heart can be seen in its form as well as its function. The heart is divided in two by a muscular wall called the septum. Each side of the heart is also divided into two additional chambers- the left and the right lower and upper chambers. The left and right upper chambers are called the atria. The left and right lower chambers are called ventricles. The right upper chamber, or right atria, is the chamber where deoxygenated blood enters the heart. The right lower chamber, or right ventricle, is the chamber into which deoxygenated blood from the right atrium flows. The left upper chamber, or left atria, is the chamber into which fresh oxygenated blood enters from the lungs and is ready to be distributed throughout the body. The left lower chamber called the left ventricle is the chamber that receives blood from the left atrium and pumps it into the aorta where it is carried to the body.
