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Common cold

Synonym: coryza What is the common cold? The common cold is an acute, self-limiting, viral inflammation of the mucosa of the upper respiratory tract. It causes nasal discharge and congestion, sneezing, a sore throat and a cough. The common cold actually describes an array of similar conditions caused by a vast number of different viruses. It is most often caused by infection with rhinoviruses (50-80%) and coronaviruses - a COVID-19 diagnosis might be considered where there is fever, loss of taste or smell, and a cough. It may also be due to infection by influenza viruses, parainfluenza viruses, respiratory syncytial virus, enteroviruses and adenovirus. Transmission of the common cold infection Routes of transmission vary between viruses but include: Inhalation of airborne respiratory droplets from people infected with the virus. Direct contact with infectious secretions. Some viruses may be spread by hand or skin contact. Common cold transmission most commonly occurs in the home, in schools and in daycare centres. The main reservoir of viruses is in young children. This is because they are more vulnerable to infection, as they have not yet developed the relevant antibodies, they shed the virus for longer following infection and they are in close contact with others. Common cold epidemiology Adults have an average of two to three colds a year. Children have an average of five to six colds a year. Young children in nursery schools may average up to twelve colds per year. It should be noted that the introduction of non-pharmacological interventions for control of COVID-19 spread has been associated with a lower rate of other respiratory viruses across Europe. Adults who are in contact with young children have more colds than those who are not. Annual epidemics occur within the colder months in temperate climates and during the rainy season in the tropics. There are over 200 viruses which cause colds; many people with cold symptoms are found to be infected with several viruses at the same time. Common cold symptoms The most frequent symptoms of the common cold are nasal discharge, nasal obstruction, sneezing, sore throat, general malaise and cough. Hoarseness, loss of taste and smell, mild burning of the eyes and a feeling of pressure in the ears or sinuses, due to obstruction and/or mucosal swelling, may also occur. Headache and fever tend to be less common symptoms. Cough is associated with 30% of colds and tends to start on about the fourth or fifth day when nasal symptoms decrease. There may be a mild increase in body temperature. Infants and young children are more likely to develop higher temperatures. In infants there may be irritability, snuffles resulting in difficulty feeding, and diarrhoea. Diagnosis may be difficult and fever can be the main symptom during the early part of the illness. Differential diagnosis Adults Allergic rhinitis: nasal itching, sneezing, watery rhinorrhoea, and nasal obstruction. It is also often accompanied by itchy, watery eyes. It can be perennial, seasonal, or due to occupational exposure. Non-allergic rhinitis: presents with chronic nasal symptoms. Pharyngitis: acute pharyngitis is caused by a variety of organisms, including the adenoviruses and Streptococcus pyogenes. This pharyngitis is often more severe than the mild-to-moderate pharyngeal discomfort in the common cold. Influenza: initially presents with systemic symptoms, including fever, rigors, headaches, myalgia, malaise and anorexia. Infectious mononucleosis (glandular fever): presents with persistent severe sore throat, fever, cervical lymphadenopathy and malaise; it is particularly common in teenagers and young adults. Whooping cough: the cough may develop later but is characteristic and is much more severe than that associated with the common cold. Children In addition to the above list, consider a foreign body in the nose. The discharge is unilateral, purulent, foul-smelling and blood-stained. Infants Consider the possibility of a more serious condition - eg, meningitis, septicaemia, pneumonia. Common cold treatment and management See also the separate Ill and Feverish Child article. General advice Explain that there are no drugs of proven benefit for the prophylaxis or treatment of the common cold, although many things have been suggested. Medical management is centred around providing symptomatic relief. Provide advice about the usual natural history of the illness and average total length of illness. (Guidelines from the National Institute for Health and Care Excellence (NICE) state the average total length of illness is 7-10 days for sore throat and 3-4 weeks for associated cough. One systematic review showed 90% of children are better within 15 days.) Explain that antibiotic treatment of upper respiratory tract infection (URTI) does not alter the clinical outcome of the illness or prevent further complications. Explain that antibiotics may also have side-effects - eg, diarrhoea, vomiting and rash. Ensure adequate fluid intake. (There are no systematic reviews to recommend or not recommend the traditional advice of increasing fluid intake.) Address any underlying concerns. Taking the time to educate people that colds are self-limiting and have no specific curative treatment may reduce anxiety and prevent unnecessary visits to the doctor in the future. Advise adequate rest but that there is usually no need to take time off school and work. Advise hygiene measures to reduce spread: frequent hand-washing, avoiding sharing towels and toys, etc. Advise about self-care and over-the-counter measures which may help with symptoms (see below). Self-care and over-the-counter options for symptom control Some people may get relief from one or more of the following: Steam inhalation - eg, by sitting in the bathroom while running a hot shower. (Beware of the risk of scalding, particularly in young children; also, evidence of effectiveness is limited.) Vapour rubs applied to the back or chest. Gargling with salt water. Sucking boiled sweets or sore-throat lozenges. Nasal drops (sodium chloride 0.9%) for nasal congestion. These may be useful for infants who are having difficulty feeding. Over-the-counter analgesia. Paracetamol and/or ibuprofen may be helpful for sore throats, headaches or temperatures. Advise these are only used in children under the age of 5 years who have a fever or are distressed. Intranasal decongestants (short-term use only) Systemic decongestants, often combined with analgesics in over-the-counter preparations for the common cold. These have a very small and very short-term benefit. Cough medicines. (Currently there is no good evidence for or against their effectiveness.) Cough classification advice The 'wet' or 'dry' classification of cough should be discontinued. Cough counting is now recognised as the gold standard for assessing antitussive activity by the US Food and Drug Administration, but because it is a recent innovation, very few of the currently available cough medicines have been assessed using this methodology. This new model and way of working holds the promise to make assessment of cough easier than previously and, importantly, is evidence-based. Evidence does NOT currently support the use of the following: Intranasal steroids. Antihistamines, but may be beneficial when combined with decongestants. Echinacea. Vitamin C. Zinc. Chinese herbal medicines (data are lacking). Garlic. Over-the-counter treatments for children under the age of 6 years Over-the-counter cough and cold measures should not be used in children under the age of 6 years. A warm drink containing honey and lemon may be used, or simple cough medicines containing honey, lemon or glycerine. There is no strong evidence for the effectiveness of honey for cough but it seems to be more effective than no treatment. However, honey is not recommended for babies aged under 1 year because of a theoretical risk of infant botulism. In 2009, the Medicines and Healthcare products Regulatory Agency (MHRA) advised that cough and cold remedies containing the following ingredients should NOT be used in children under the age of 6 years, as the risk-benefit balance is unfavourable: Antitussives (dextromethorphan and pholcodine). Expectorants (guaifenesin and ipecacuanha). Nasal decongestants (ephedrine, oxymetazoline, phenylephrine, pseudoephedrine, and xylometazoline). Antihistamines (brompheniramine, chlorphenamine, diphenhydramine, doxylamine, promethazine, and triprolidine). Over the age of 6 years, these medications may be used if other self-care measures have not eased symptoms, and for a maximum of five days, and providing only one cold remedy is used at a time. Follow-up Advise people to return if their symptoms are worsening, or if they have not improved after two weeks. For young children and babies, advise early review if they are not feeding, if there are any symptoms of dehydration, if they have a persistent fever or if they have any difficulty breathing. Consider arranging a review for people at high risk of complication (eg, significant comorbidity, immunosuppression) and advise them to attend urgently if their condition worsens. Complications Complications with the common cold are usually due to viral spread, or secondary bacterial infection. They are more likely in: Smokers. Those with immunosuppression through disease or treatment. Young children born prematurely. Elderly people. Those with significant comorbidity, particularly asthma, chronic obstructive pulmonary disease (COPD), diabetes mellitus, and cystic fibrosis, as well as those with any significant cardiac, renal, liver or neuromuscular disease. Common complications include: Sinusitis (0.5-2% of cases). Otitis media (as many as 20% of young children with the common cold). Croup in very young children and babies. Chest infections: bronchiolitis in the very young, acute bronchitis, pneumonia, and exacerbations of COPD or asthma. Prognosis In the majority, the common cold is a mild, self-limiting illness. The common cold usually lasts around a week in adults and 10-14 days in children. In 90% of children, symptoms have resolved by 15 days. Cigarette smokers are likely to have a more severe and more prolonged illness than non-smokers and are significantly more likely to develop a chest infection as a complication. People with COPD who have a rhinovirus infection are more likely to have a longer duration of illness, a more severe illness and to cough for longer afterwards than those without lung disease. Common cold prevention Preventing the spread of the common cold is very difficult but simple measures to prevent the spread of acute respiratory infections, such as hand washing (especially around younger children), are thought to be moderately effective. The role of mask wearing is less clear. The effectiveness of adding virucidals or antiseptics to normal handwashing to decrease transmission remains uncertain and hasn't been recently updated. People with colds should also avoid close contact (eg, hugging, kissing) and avoid sharing towels and flannels. Children should be discouraged from sharing toys belonging to a child with a cold. Some work has been done on looking for a vaccine for the common cold but this is difficult because of the antigenic variability of the cold viruses and the numerous other indistinguishable infective agents.

30 May 2022


What is sepsis? Sepsis is defined as life-threatening organ dysfunction due to a dysregulated host response to infection. Septic shock is associated with particularly profound circulatory, cellular and metabolic abnormalities, with a greater risk of mortality than with sepsis alone. Sepsis is defined as life-threatening organ dysfunction due to a dysregulated host response to infection. Septic shock describes circulatory, cellular, and metabolic abnormalities which are associated with a greater risk of mortality than sepsis alone. Patients with septic shock can be clinically identified by a vasopressor requirement to maintain a mean arterial pressure of 65 mm Hg or greater and serum lactate level greater than 2 mmol/L in the absence of hypovolaemia. This combination is associated with hospital mortality rates greater than 40%. The Surviving Sepsis Campaign (SSC) was established to raise awareness of severe sepsis and to improve its management. The SSC is a collaboration between several groups worldwide and its aim is to reduce the mortality from sepsis. Pathophysiology of sepsis The exact pathophysiology of sepsis is unknown, but it is thought to be a multifactorial response to an infecting pathogen that may be amplified by host factors (eg, genetics, age, and co-morbidities), the pathogen (type, virulence, and burden), and the environment. The exact mechanism of cell injury is not fully known, but it is suspected that immune and coagulation systems are switched on by infection and cause dysfunction of one or more organs with variable severity. It is thought this involves the early activation of both pro-inflammatory responses (leading to cellular and tissue damage) and anti-inflammatory responses (leading to immunosuppression). Resulting tissue hypoxia, mitochondrial dysfunction, macrovascular and microvascular dysfunction, and cell death are thought to be mediators of organ dysfunction. The most common sites of infection leading to sepsis are the respiratory, gastrointestinal, renal and genitourinary tracts, as well as blood, skin, soft tissue, bone and joint sources. Studies indicate an equal prevalence of Gram-positive and Gram-negative bacterial infections in sepsis, particularly Staphylococcus aureus, Pseudomonas species, and Escherichia coli. In children, Neisseria meningitides and Haemophilus influenzae may also be involved. Rarely, fungal, viral, or parasitic infections are the cause. No causative pathogen is identified in about one-third of people with sepsis. How common is sepsis? (Epidemiology) Sepsis is a leading cause of morbidity and mortality for children worldwide. Globally, an estimated 22 cases of childhood sepsis per 100,000 person-years and 2,202 cases of neonatal sepsis per 100,000 live births occur, translating into 1.2 million cases of childhood sepsis per year. The most recent global estimates for sepsis incidence and mortality were based on data for adults admitted to hospital in seven high-income countries and reported 19.4 million sepsis incident cases and 5.3 million sepsis-related deaths annually. As only high-income countries are represented this may be a significant underestimate. However, it has been deduced that more than 1 in 1,000 people in developed countries develop sepsis each year and between a third and a half of them progress to severe sepsis. The figures for developing countries are likely to be far higher. Risk factors There is usually an abscess or nidus of infection, which may be occult. Risk factors for developing sepsis include the following: The very young (under 1 year) and older people (over 75 years), or people who are very frail. People who have impaired immune systems because of illness or drugs, including: People having treatment for cancer with chemotherapy. People who have impaired immune function (eg, people with diabetes, people who have had a splenectomy, or people with sickle cell disease. People taking long-term steroids. People taking immunosuppressant drugs to treat non-malignant disorders such as rheumatoid arthritis. People who have had surgery, or other invasive procedures, in the past 6 weeks. People with any breach of skin integrity (eg, cuts, burns, blisters or skin infections. People who misuse drugs intravenously. People with indwelling lines or catheters. People who are pregnant, have given birth or had a termination of pregnancy or miscarriage in the past 6 weeks. Risk factors for early-onset neonatal infection: Suspected or confirmed infection in another baby in the case of a multiple pregnancy. Invasive group B streptococcal infection in a previous baby or maternal group B streptococcal colonisation, bacteriuria or infection in the current pregnancy. Pre-term birth following spontaneous labour before 37 weeks' gestation. Confirmed rupture of membranes for more than 18 hours before a pre-term birth. Confirmed prelabour rupture of membranes at term for more than 24 hours before the onset of labour. Intrapartum fever higher than 38°C if there is suspected or confirmed bacterial infection. Chorioamnionitis. Symptoms of sepsis (presentation) Patients may have presented a few days earlier with a focus of infection. Patients may then deteriorate rapidly despite having the appropriate oral antibiotics. People with sepsis may have non-specific, non-localised presentations, eg, feeling very unwell, and may not have a high temperature. There may be concerns expressed by the person and their family or carers, eg, changes from usual behaviour. Also enquire about symptoms relating to a possible focus of infection - eg, cough, urinary symptoms, recent travel. Ask about frequency of micturition in the past 18 hours. Presenting features for children may include feeling abnormally cold to touch, looking mottled and blue or with very pale skin, a rash that does not fade with pressure, raised respiratory rate and being very lethargic and difficult to wake up. Young children may not feed, may have repeated vomiting or may not pass any urine and so not have wet nappies. Assessment A high degree of vigilance is required for early identification of a patient with sepsis in primary care. Evaluate risk level using the person's history, physical examination results and criteria based on age. The NICE guideline includes stratification of risk from sepsis in under 5s, children aged 5 to 11, children and young people aged 12 to 15, and for those aged 16 years and older. Assess people with any suspected infection to identify: Possible source of infection. Factors that increase risk of sepsis. Any indications of clinical concern, such as new-onset abnormalities of behaviour, circulation or respiration. Use a structured set of observations to assess people in a face-to-face setting to stratify risk if sepsis is suspected. Ask how often the person urinated in the past 18 hours, any recent fever or rigors, and whether they have recently presented with symptoms or signs that could indicate sepsis. Use the national early warning score (NEWS2) - see 'Sepsis screening' below - to assess people with suspected sepsis who are aged 16 or over, are not and have not recently been pregnant, and are in an acute hospital setting, acute mental health setting or ambulance. Consider using an early warning score to assess people with suspected sepsis who are: Aged under 16, in any setting. Pregnant or have recently been pregnant, in any setting. Aged 16 or over, in a community or custodial setting. Suspect neutropenic sepsis in people who become unwell and: Are having or have had systemic anticancer treatment within the last 30 days. Are receiving or have received immunosuppressant treatment for reasons unrelated to cancer. Use clinical judgement to determine whether any past treatment may still be likely to cause neutropenia. Refer patients with suspected neutropenic sepsis immediately for assessment in secondary or tertiary care. Initial examination Assess temperature, heart rate, respiratory rate, blood pressure, level of consciousness, oxygen saturation and capillary refill time. In community settings, measure oxygen saturation if equipment is available and taking a measurement does not cause a delay in assessment or treatment. Examine people with suspected sepsis for (see also Meningococcal Disease): Mottled or ashen appearance. Cyanosis of the skin, lips or tongue. Non-blanching petechial or purpuric rash. Any breach of skin integrity (eg, cuts, burns or skin infections). Other rash indicating potential infection. As part of the initial assessment, carry out a thorough clinical examination to look for sources of infection, including sources that might need drainage or other interventions. Sepsis screening The National Early Warning Score (NEWS) is a tool developed by the Royal College of Physicians which improves the detection and response to clinical deterioration in adult patients and is a key element of patient safety and improving patient outcomes. The National Early Warning System (NEWS) was introduced by the Royal College of Physicians in 2012. In December 2017, an updated version of NEWS, NEWS2, was published. See the reference link for further information. The National Early Warning System (NEWS2) is based on a simple scoring system in which a score is allocated to physiological measurements already undertaken when patients present to, or are being monitored in, hospital. NEWS is more accurate in predicting 10- and 30-day mortality than other systems when patients present to A&E with suspected sepsis. Six simple physiological parameters form the basis of the scoring system: 1. Respiratory rate 2. Oxygen saturations 3. Temperature 4. Systolic blood pressure 5. Pulse rate 6. Level of consciousness A score is allocated to each as they are measured, the magnitude of the score reflecting how extremely the parameter varies from the norm. The score is then aggregated. Evidence suggests using the system is associated with improved patient outcomes. Management of sepsis The following is a brief summary of the NICE guidance. See the reference link to the NICE guideline for further information. Managing suspected sepsis outside acute hospital settings Refer people with suspected sepsis for emergency medical care if: They meet any high risk criteria, or Their immunity is impaired by drugs or illness and they meet any moderate to high risk criteria. Use the most appropriate means of transport (usually 999 ambulance). Pre-alert secondary care (through GP or ambulance service) when any high risk criteria are met in a person under 16 with suspected sepsis outside of an acute hospital, and transfer them immediately. Managing the condition while awaiting transfer In remote and rural locations where transfer time to emergency department is routinely more than 1 hour, ensure GPs have mechanisms in place to give antibiotics to people with high risk criteria in pre-hospital settings. If immediate transfer to hospital is not required Assess people who are outside acute hospital settings with suspected sepsis and any moderate to high risk criteria to: Make a definitive diagnosis of their condition. Decide whether their condition can be treated safely outside hospital. If a definitive diagnosis is not reached or the person's condition cannot be treated safely outside an acute hospital setting, refer them urgently for emergency care. Managing suspected sepsis in acute hospital settings Initial investigations to find the source of infection Start looking for the source of infection and take microbiological and blood samples before giving an antimicrobial. Initial blood tests should include blood gas, including glucose and lactate measurement, blood culture, full blood count, C-reactive protein, renal function and electrolytes, liver function tests and clotting screen. Give a broad-spectrum antimicrobial at the maximum recommended dose, without delay (within 1 hour of identifying that they meet any high risk criteria), if antibiotics have not already been given for this episode of sepsis. When the source of infection is confirmed or microbiological results are available: review the choice of antibiotic(s) and change the antibiotic(s) according to results, using a narrower-spectrum antibiotic, if appropriate. Give intravenous fluid bolus without delay (within 1 hour of identifying that they meet any high risk criteria). Refer to a critical care specialist or team for them to review, including their need for central venous access and initiation of inotropes or vasopressors. See the NICE guideline reference link for further information. Prognosis Organ dysfunction is an important predictor of prognosis, with multiple organ involvement being associated with a higher risk of mortality. Extremes of age and the presence of co-morbidities are also associated with a worse prognosis. A UK Sepsis Trust report cites an overall mortality rate in England of 28.9%. A UK observational cohort study of 91 intensive care units (n = 56,673) found that the hospital mortality rate of adults admitted with sepsis ranged from 17% in people aged 16–19 years, to 64% in people aged over 85 years. A diagnosis of septic shock is associated with hospital mortality rates greater than 40%. An international study of the association between following Surviving Sepsis Campaign (SSC) performance criteria and mortality rate found the overall hospital mortality for people with sepsis and septic shock was 32.8%. The case fatality rate of sepsis may be falling over time, presumably due to increased awareness and reporting of suspected sepsis, faster diagnosis, and improved management protocols. Survivors of sepsis have higher rates of mortality following hospital discharge compared with control populations. Compared to non-sepsis admissions, sepsis survivors have a greater risk of re-admission, with 30-day re-admission rates averaging between 19–32%. People who survive sepsis may have long-term physical, psychological, and cognitive impairments. Complications of sepsis Death (see 'Prognosis' section above). Organ failure: this may be multi-system and includes acute kidney injury, cholestasis, heart failure, acute respiratory distress syndrome (ARDS) or acute lung injury, and bone marrow suppression. Recurrent and secondary infection. Malnutrition. Coagulopathy: this may cause thromboembolism or disseminated intravascular coagulation (DIC) characterised by microthrombosis and haemorrhage. Physical impairments: a reduced quality of life may result from chronic pain and fatigue. Encephalopathy and delirium may lead to reduced mobility and neuromuscular weakness, as well as longer lasting neurocognitive deficits such as memory problems and reduced concentration. Psychological sequelae may include anxiety about recurrent infection and sepsis, post-traumatic stress disorder, loss of confidence and self-esteem. Post-sepsis syndrome Post-sepsis syndrome (PSS) is associated with several pathophysiologic mechanisms that negatively affect quality of life, long-term health and lifespan. These pathophysiologic mechanisms include immune dysregulation, persistent inflammation, oxidative stress and mitochondrial dysfunction. PSS can manifest in various ways including: Physical difficulties include fatigue, weakness, breathlessness, chest pains, oedema, arthralgia, poor appetite, visual disturbance, sensory disturbance and recurrent infections. Psychological difficulties may include anxiety, depression, post-traumatic stress disorder, nightmares, insomnia, poor concentration and memory disturbance. Original document (2016) produced in collaboration with Dr Ron Daniels of The UK Sepsis Trust.

21 Feb 2024

Important complications of anaesthesia

Anaesthesia Anaesthesia is from the Greek and means 'loss of sensation'. Anaesthesia allows invasive and painful procedures to be performed with little distress to the patient. There are three main types of anaesthesia. General anaesthesia The patient is sedated, using either intravenous medications or gaseous substances, and occasionally muscles paralysed, requiring control of breathing by mechanical ventilation. Regional anaesthesia This can be described as central where anaesthetic drugs are administered directly in or around the spinal cord, blocking the nerves of the spinal cord (eg, epidural or spinal anaesthesia). The main benefit of this method is that ventilation is not needed (provided the block is not too high). Regional anaesthesia can also be peripheral - for example: Plexus blocks - eg, brachial plexus. Nerve blocks - eg, femoral. Intravenous blocks whilst preventing venous flow out of the region - eg, Bier's block. Local anaesthesia In this method the anaesthetic is applied to one site, usually topically or subcutaneously. Important complications of general anaesthesia The practice of anaesthesia is fundamental to the practice of medicine. However, anaesthesia is not without its problems. It is difficult to determine exactly the incidence of deaths directly attributable to general anaesthetics, as the cause of death is often multifactorial and study methodology varies making comparisons difficult. In 1987 a confidential enquiry into perioperative deaths revealed that very few deaths were actually as a direct result of general anaesthesia - there was an incidence of 1 in 185,086 (first Confidential Enquiry into Perioperative Deaths (CEPOD)). More recently in a Swiss single tertiary centre data analysis between 2003 and 2019, 1.5 deaths occurred for every 100,000 patients. Figures of anaesthetic-related morbidity are more difficult to determine. Although general anaesthesia is not without risk, it should be remembered that it allows necessary procedures to be performed in a humane way - without which the patient might otherwise die. Along these lines, if a patient is high-risk for a general anaesthetic (eg, pre-existing comorbidities) then they should still be referred for surgery like any other patient. The decision to operate and which form of anaesthesia to use should then be decisions made by the surgeon and anaesthetist. Important complications of general anaesthesia Important information Pain. Nausea and vomiting - up to 30% of patients. Damage to teeth. Sore throat and laryngeal damage. Anaphylaxis to anaesthetic agents - approximately 1 in 3,000. Cardiovascular collapse. Respiratory depression. Aspiration pneumonitis - non-obstetric emergency rate between 1 in 373 to 1 in 895. Hypothermia. Hypoxic brain damage. Nerve injury. Awareness during anaesthesia. Embolism - air, thrombus, venous or arterial. Backache. Headache. Idiosyncratic reactions related to specific agents - eg, malignant hyperpyrexia with suxamethonium, succinylcholine-related apnoea. Iatrogenic - eg, pneumothorax related to central line insertion. Death. Some specific complications of general anaesthesia Anaphylaxis Anaphylaxis can occur to any anaesthetic agent and in all types of anaesthesia. The severity of the reaction may vary but features may include rash, urticaria, bronchospasm, hypotension, angio-oedema, and vomiting. It needs to be carefully looked for in the pre-operative assessment and previous general anaesthetic charts may help. Patients who are suspected of an allergic reaction should be referred for further investigation to try to determine the exact cause. If necessary, this may involve provocation testing or skin prick testing and patients should be referred to local immunologists. Anaphylaxis needs to be promptly recognised and managed and patients should be advised to wear a medical emergency identification bracelet or similar once they recover. Aspiration pneumonitis A reduced level of consciousness can lead to an unprotected airway. If the patient vomits they can aspirate the vomitus contents into their lungs. This can set up lung inflammation with infection. The risk of aspiration pneumonitis and aspiration pneumonia is reduced by fasting for several hours prior to the procedure and cricoid cartilage pressure during induction of anaesthesia. However, the evidence for the use of cricoid pressure is not clearly documented and further investigation is required. Other methods of reducing aspiration pneumonitis associated with anaesthesia are the use of metoclopramide to enhance gastric emptying or proton pump inhibitors to increase the pH of gastric contents. Aspiration pneumonitis may also occur in spinal anaesthesia if the level of spinal block is too high, leading to paralysis or impairment of the vocal cords and respiratory impairment. Peripheral nerve damage This can occur with all the types of anaesthesia and results from nerve compression. The most common cause is exaggerated positioning for prolonged periods of time. Both the anaesthetist and the surgeons should be aware of this potential complication and patients should be moved on a regular basis if possible. The severity varies and recovery may be prolonged. The most common nerves affected are the ulnar nerve and the common peroneal nerve. More rarely, the brachial plexus may be affected. Injury to nerves can be avoided by prevention of extreme postures for lengthy periods during surgery. If nerve damage occurs then patients should be followed up and further investigations such as electromyography may be required. Damage to teeth It is now common practice to check the teeth in the anaesthetist's pre-operative assessment. Damage to teeth is actually the most common cause of claims made against anaesthetists. In a 2023 systematic review and meta-analysis, during the peri-operative period, the majority of dental injuries (50–75%) occur during tracheal intubation. The overall incidence of dental injury is estimated to be between 0.06% and 12%, but these values may be underestimated. The tooth most commonly affected is the upper left incisor. Embolism Embolism is rare during an anaesthetic but is potentially fatal. Air embolism occurs more commonly during neurosurgical procedures or pelvic operations. Prophylaxis of thromboembolism is common and begins pre-operatively with thromboembolic deterrents (TEDS) and low molecular weight heparin (LMWH). Important complications of regional anaesthesia Central regional anaesthesia was first used at the end of the 18th century. It provided a method of blocking afferent and efferent nerves by injecting anaesthetic agents in either the epidural space around the spinal cord (epidural anaesthesia) or directly in the cerebrospinal fluid surrounding the spinal cord (ie in the subarachnoid space called spinal anaesthesia). All nerves are blocked including motor nerves, sensory nerves and nerves of the autonomic system. Epidural anaesthesia takes slightly longer than spinal anaesthesia to take effect and provides predominantly analgesic properties. With both, the need for muscle paralysis and ventilation is not usually required but there is a risk that a high block will impair respiration, meaning that ventilation will be necessary. A 2017 Cochrane systematic review showed that regional anaesthesia is associated with reduced mortality and reduction in serious complications in comparison with general anaesthesia. However, a 2022 systematic review and meta-analysis of RCTs comparing outcomes in those having general anaesthetic or spinal anaesthetic showed that spinal anaesthesia reduced the risk of acute kidney injury compared with GA: RR=0.59 (95% CI, 0.39-0.89), but there were no significant differences in the risk of other outcomes. Important complications of regional anaesthesia Important information Pain - patients may still experience pain despite spinal anaesthesia. Post-dural headache from cerebrospinal fluid (CSF) leak. Hypotension and bradycardia through blockade of the sympathetic nervous system. Limb damage from sensory and motor block. Epidural or intrathecal bleed. Respiratory failure if block is 'too high'. Direct nerve damage. Hypothermia. Damage to the spinal cord - may be transient or permanent. Spinal infection. Aseptic meningitis. Haematoma of the spinal cord - enhanced by use of LMWH pre-operatively. Anaphylaxis. Urinary retention. Spinal cord infarction. Anaesthetic intoxication. Some specific complications of regional anaesthesia Post-dural puncture headache Post-dural puncture headache is very common after spinal anaesthesia and especially in young adults and obstetrics. Unintentional dural puncture occurs in 0.15-1.5% of labour epidural analgesia and 50-80% of these women develop post-dural puncture headache. The headache results from CSF leak from the puncture site. It is increased by use of larger-gauge needles and reduced by atraumatic needles. Presenting symptoms may include headache, photophobia, vomiting and dizziness. Post-dural puncture headache is usually treated with analgesia, bed rest and adequate hydration. Occasionally epidural blood patch is used where 15 ml of the patient's blood are injected at the site of the meningeal tear. Caffeine is also used and acts as a stimulant of the CNS and has shown benefit. Other medications with benefit include gabapentin, theophylline and hydrocortisone. Total spinal block Total spinal block can occur with the injection of large amounts of anaesthetic agents into the spinal cord. It is detected by a high sensory level and rapid muscle paralysis. The block moves up the spinal cord so that respiratory embarrassment may occur, as can unconsciousness. In these situations the patient needs prompt assessment and may need to be intubated and ventilated until the spinal block wears off. The quoted incidences vary between 1 in 2,971 and 1 in 16,200 anaesthetics. Hypotension Hypotension during spinal anaesthesia for elective caesarean delivery occurs in as many as 70% to 80% of women receiving pharmacological prophylaxis. They develop transient hypotension as sympathetic nerves are blocked. This usually responds to prompt fluid replacement, usually starting with crystalloids followed by colloids. Occasionally hypotension can be severe and may require vasopressors along with fluids. Care must be taken in patients with a cardiac history, as they may develop myocardial ischaemia with minor drops in blood pressure. It is suggested that heart rate variability prior to spinal anaesthesia represents autonomic dysfunction and may help determine patients who are more likely to develop hypotension. Cases of bradycardia with asystole leading to cardiac arrest have also occurred and it appears the underlying aetiology is complicated and not just related to autonomic dysfunction. Neurological deficits Cauda equina syndrome may occur and can be transient or permanent. This is a common reason for patients to refuse spinal anaesthesia. There may also be traumatic injury to the spinal cord. Adhesive arachnoiditis is a longer-term sequela of spinal anaesthesia, occurring weeks and even months later. It is characterised by proliferation of the meninges and vasoconstriction of spinal cord blood vessels. This results in gradual sensory and motor deficits from ischaemia and infarction of the spinal cord. Important complications of local anaesthesia All forms of anaesthetics are invasive to a patient and therefore consent should be obtained as for other procedures. Ideally patients should be given a leaflet regarding anaesthesia and then counselled regarding the intended benefits and the risks of anaesthesia. In a general practice setting it will be the responsibility of the clinician who administers the local anaesthesia to ensure fully informed, non-coercive consent is obtained.

14 Feb 2024

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