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Lung Transplantation

Lung transplantation is a surgical procedure in which a patient’s diseased lungs are partially or totally replaced by lungs which come from a donor. While lung transplants carry certain associated risks, they can also extend life expectancy and enhance the quality of life for end-stage pulmonary patients.

Types of Lung Transplants

Lobe
A lobe transplant is a surgery in which part of a living donor’s lung is removed and used to replace part of recipient’s diseased lung. This procedure usually involves the donation of lobes from two different people, thus replacing a single lung in the recipient. Donors who have been properly screened should be able to maintain a normal quality of life despite the reduction in lung volume.

Single-lung
Many patients can be helped by the transplantation of a single healthy lung. The donated lung typically comes from a donor who has been pronounced brain-dead.

Double-lung
Certain patients may require both lungs to be replaced. This is especially the case for people with cystic fibrosis, due to the bacterial colonisation commonly found within such patients’ lungs; if only one lung were transplanted, bacteria in the native lung could potentially infect the newly transplanted organ.

Heart-lung
Some respiratory patients may also have severe cardiac disease which in of itself would necessitate a heart transplant. These patients can be treated by a surgery in which both lungs and the heart are replaced by organs from a donor or donors.

Procedure
A single lung transplant takes about four to eight hours, while a double lung transplant takes about six to twelve hours to complete. A history of prior chest surgery may complicate the procedure and require additional time.

Single Lung
In single-lung transplants, the lung with the worse pulmonary function is chosen for replacement. If both lungs function equally, then the right lung is usually favored for removal because it avoids having to maneuver around the heart, as would be required for excision of the left lung.
In a single-lung transplant the process starts out after the donor lung has been inspected and the decision to accept the donor lung for the patient has been made. An incision is generally made from under the shoulder blade around the chest, ending near the sternum. An alternate method involves an incision under the breastbone. In the case of a singular lung transplant the lung is collapsed, the blood vessels in the lung tied off, and the lung removed at t the bronchial tube. The donor lung is placed, the blood vessels reattached, and the lung reinflated. To make sure the lung is satisfactory and to clear any remaining blood and mucus in the new lung a bronchoscopy will be performed. When the surgeons are satisfied with the performance of the lungs, the chest incision will be closed.

Incision scarring from a double lung transplant.

Double Lung
A double-lung transplant, also known as a bilateral transplant, can be executed either sequentially, en bloc, or simultaneously. Sequential is more common than en bloc. This is effectively like having two separate single-lung transplants done. A less common alternative is the transplantation of both lungs en bloc or simultaneously.
The transplantation process starts after the donor lungs are inspected and the decision to transplant has been made. An incision is then made from under the patient’s armpit, around to the sternum, and then back towards the other armpit, this is known as a clamshell incision. In the case of a sequential transplant the recipients’ lung with the poorest lung functions is collapsed, the blood vessels tied off, and cut at the corresponding bronchi. The new lung is then placed and the blood vessels reattached. To make sure the lung is satisfactory before transplanting the other a bronchoscopy is performed. When the surgeons are satisfied with the performance of the new lung, surgery on the second lung will proceed. In 10% to 20% of double-lung transplants the patient is hooked up to a heart-lung machine which pumps blood for the body and supplies fresh oxygen.

Risks
The newly transplanted lung itself may fail to properly heal and function. Because a large portion of the patient’s body has been exposed to the outside air, sepsis is a possibility, so antibiotics will be given to try to prevent that.
Because the transplanted lung or lungs come from another person, the recipient’s immune system will “see” it as an invader and attempt to neutralize it. Transplant rejection is a serious condition and must be treated as soon as possible.

Signs of rejection:
1. Fever
2. flu-like symptoms, including chills, dizziness, nausea, general feeling of illness
3. increased difficulty in breathing
4. worsening pulmonary test results
5. increased chest pain or tenderness

Breathing

Breathing Part

Breathing takes oxygen in and carbon dioxide out of the body. Aerobic organisms require oxygen to create energy via respiration, in the form of the metabolism of energy-rich molecules such as glucose. The medical term for normal relaxed breathing is eupnea.

Breathing is only part of the processes of delivering oxygen to where it is needed in the body and removing carbon dioxide waste. The process of gas exchange occurs in the alveoli by passive diffusion of gases between the alveolar gas and the blood passing by in the lung capillaries. Once in the blood the heart powers the flow of dissolved gases around the body in the circulation.

As well as carbon dioxide, breathing also results in loss of water from the body. Exhaled air has a relative humidity of 100% because of water diffusing across the moist surface of breathing passages and alveoli.

In mammals, breathing in, or inhaling, is usually an active movement, with the contraction of the diaphragm muscle. This is known as negative pressure breathing. The diaphragm’s normal relaxed position is that of a recoiled one (decreasing the thoracic volume) whereas in the contracted position it is pulled downwards (increasing the thoracic volume). This process works in conjunction with the intercostal muscles connected to the rib cage. Contraction of these muscles lifts the rib cage, thus aiding in increasing the thoracic volume. Relaxation of the diaphragm compresses the lungs, effectively decreasing their volume while increasing the pressure inside them. The intercostal muscles hereby also relax, further decreasing the volume of the lungs.

With a pathway to the mouth or nose clear, this increased pressure forces air out of the lungs. Conversely, contraction of the diagraphm increases the volume of the (partially empty) lungs, decreasing the pressure inside, which creates a partial vacuum. Environmental air then follows its pressure gradient down to fill the lungs.

At rest, breathing out, or exhaling, is a combination of passive and active processes powered by the elastic recoil of the alveoli, similar to a deflating balloon, and the contraction of the muscular body wall. The following organs are used in respiration: the mouth; the nose and nostrils; the pharynx; the larynx; the trachea; the bronchi and bronchioles; the lungs; the diaphragm; and the terminal branches of the respiratory tree, such as the alveoli.

Extra Information

Artificial respiration is the act of simulating respiration, which provides for the overall exchange of gases in the body by pulmonary ventilation, external respiration and internal respiration. This means providing air for a person who is not breathing or is not making sufficient respiratory effort on their own. [It must be used on a patient with a beating heart or as part of cardiopulmonary resuscitation in order to achieve the internal respiration.

Pulmonary ventilation (and hence external respiration) is achieved through manual insufflation* of the lungs either by the rescuer blowing into the patient’s lungs, or by using a mechanical device to do so. This method of insufflation has been proved more effective than methods which involve mechanical manipulation of the patient’s chest or arms, such as the Silvester method. It is also known as Expired Air Resuscitation (EAR), Expired Air Ventilation (EAV) and mouth-to-mouth resuscitation.

*Insufflation.
Insufflation is also known as ‘rescue breaths’ or ‘ventilations’, is the act of mechanically forcing air into a patient’s respiratory system. This can be achieved via a number of methods, which will depend on the situation and equipment available.

Methods Include :

! Mouth to mouth – This involves the rescuer making a seal between their mouth and the patient’s mouth and ‘blowing’, in order to pass air into the patient’s body
! Mouth to nose – In some instances, the rescuer may need or wish to form a seal with the patient’s nose. Typical reasons for this include maxillofacial injuries, performing the procedure in water or the remains of vomit in the mouth
! Mouth to mouth and nose – Used on infants (usually up to around 1 year old), as this forms the most effective seal
! Mouth to mask – Most organisations recommend the use of some sort of barrier between rescuer and patient to reduce cross infection risk.
! Bag valve mask (BVM) – This is a simple device manually operated by the rescuer, which involves squeezing a bag in order to expel air into the patient.
! Mechanical resuscitator – An electric unit designed to breathe for the patient.

Hypoventilation (also known as respiratory depression) occurs when ventilation is inadequate to perform needed gas exchange. It generally causes an increased concentration of carbon dioxide (hypercapnia) and respiratory acidosis. It can be caused by medical conditions, by holding one’s breath, or by drugs, typically when taken in overdose. Hypoventilation may be dangerous for those with sleep apnea. [Sleep apnea is a sleep disorder characterized by pauses in breathing during sleep.]
The opposite condition is hyperventilation (too much ventilation), resulting in low carbon dioxide levels (hypocapnia).

Extra Extra Knowledge

In animal physiology, respiration is the transport of oxygen from the outside air to the cells within tissues and the transport of carbon dioxide in the opposite direction. This is in contrast to the biochemical definition of respiration, which refers to cellular respiration: the metabolic process by which an organism obtains energy by reacting oxygen with glucose to give water, carbon dioxide and ATP (energy). Although physiologic respiration is necessary to sustain cellular respiration and thus life in animals, the processes are distinct: cellular respiration takes place in individual cells of the animal, while physiologic respiration concerns the bulk flow and transport of metabolites between the organism and external environment.
In unicellular organisms, simple diffusion is sufficient for gas exchange: every cell is constantly bathed in the external environment, with only a short distance for gases to flow across. In contrast, complex multicellular animals such as humans have a much greater distance between the environment and their innermost cells, thus, a respiratory system is needed for effective gas exchange. The respiratory system works in concert with a circulatory system to carry gases to and from the tissues.
In air-breathing vertebrates such as humans, respiration of oxygen includes four stages:

! Ventilation, moving of the ambient air into and out of the alveoli of the lungs.
! Pulmonary gas exchange, exchange of gases between the alveoli and the pulmonary capillaries
! Gas transport, movement of gases within the pulmonary capillaries through the circulation to the peripheral capillaries in the organs, and then a movement of gases back to the lungs along the same circulatory route.
! Peripheral gas exchange, exchange of gases between the tissue capillaries and the tissues or organs, impacting the cells composing these and mitochondria within the cells.

Note that ventilation and gas transport require energy to power a mechanical pump (the heart) and the muscles of respiration, mainly the diaphragm. In heavy breathing, energy is also required to power additional respiratory muscles such as the intercostal muscles. The energy requirement for ventilation and gas transport is in contrast to the passive diffusion taking place in the gas exchange steps.

Thats all for Chapter 10 Respiration.

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