The Royal Marsden Hospital Manual of Clinical Nursing Procedures - Lisa Dougherty [380]
Complications
Hypoxia
The act of suctioning reduces vital lung volume from the lungs and upper airways. Each suctioning procedure should last no longer than 10 seconds to decrease the risk of trauma, hypoxia and other side-effects (ICS 2008). Ventilator disconnection or the removal of the oxygen supply will also add to the risk of hypoxia prior to suctioning. Within a critical care setting, this risk can be avoided by hyperoxygenating the lungs with 100% oxygen, either manually or via a ventilator (Glass and Grap 1995, Hough 2001), which should be considered for all patients with high oxygen requirements.
Cardiac arrhythmias
Arrhythmias may be brought about by the onset of hypoxaemia or a vagal reflex instigated by tracheal stimulation by the catheter (MacIntyre and Branson 2009).
Raised intracranial pressure
This may occur if the suction catheter causes excessive tracheal stimulation and results in coughing and an increase in the patient’s intrathoracic pressure, both of which compromise cerebral venous drainage (Pryor and Prasad 2008).
Cardiopulmonary resuscitation
Definition
The term cardiac arrest implies a sudden interruption of cardiac output. It may be reversible with appropriate treatment (Handley 2004). The patient will collapse, lose consciousness, stop breathing and will be pulseless (Jevon 2001, Paradis 2007).
The four arrhythmias that cause cardiac arrest are:
asystole
ventricular fibrillation (VF)
pulseless ventricular tachycardia (VT)
pulseless electrical activity (PEA).
For the purposes of resuscitation guidelines, these rhythms are divided into two groups by their treatment:
VF and pulseless VT, which require defibrillation
non-VF/VT, which do not require defibrillation (Resuscitation Council 2005).
Resuscitation is the emergency treatment of any condition in which the brain fails to receive enough oxygen.
Anatomy and physiology
The heart
The heart is made up of four chambers: two upper atria and two lower ventricles (see Figure 10.5 Conduction of the heart). The right atrium receives deoxygenated blood via the venous circulation. From the right atrium, blood flows into the right ventricle which pumps it into the lungs via the pulmonary arteries. Carbon dioxide is released and oxygen is absorbed. This blood is called oxygenated and returns to the heart via the pulmonary veins that empty into the left atrium. The blood then passes into the left ventricle which pumps it into the aorta and arterial circulation (Waugh and Grant 2010).
The atrioventricular septum completely separates the right and left sides of the heart. From shortly after birth, the two sides of the heart never directly communicate. Blood travels from right side to left side via the lungs only. However, the chambers themselves work together. The two atria contract simultaneously, and the two ventricles contract simultaneously (Waugh and Grant 2010).
To prevent backflow of blood, the heart has valves. The atrioventricular (AV) valves are between the atria and ventricles. The right AV valve between the right atrium and right ventricle is also called the tricuspid valve because it consists of three cusps. The left AV valve between the left atrium and ventricle is called the bicuspid as it has two cusps. Both arteries that emerge from the heart have a valve to prevent blood from flowing back into the heart – the semi-lunar (SL) valves. The pulmonary SL valve lies where the pulmonary trunk leaves the right ventricle and the aortic SL valve is situated at the opening between the aorta and left ventricle. The valves open and close in response to pressure changes as the heart contracts and relaxes (Moran 2010, Tortora and Derrickson 2009).
Cardiac conduction system
This pathway is made up of the:
sinoatrial (SA) node
AV node
bundle of His
left and right bundle branches
Purkinje fibres.
The SA node is the natural pacemaker of the heart.