Neurological Complications in Aortic Valve Surgery and Rehabilitation Treatment Used

Around the second decade of the twentieth century there was speculation about the possibility of cardiac surgery and its possible consequences in the central nervous system. To reduce these potential consequences as much as possible, research was carried out into three different approaches: systemic hypothermia, by placing the patient in a bath of icecold water, cross circulation between two people, and cardiopulmonary bypass (CPB) with a roller pump and an artificial oxygenator (Clau Terre, 2009). Shortly after using these procedures, it became clear there was an advantage provided by the CPB technique with an independent oxygenator and normal systemic flows that neither cross-circulation nor surface hypothermia could provide. It thus became possible to address increasingly complex congenital heart disease and ventricular septal defects, tetralogy of Fallot and other more complex examples. With the introduction of CPB, early neurological complications such as coma, cognitive impairment, strokes, etc. began to appear.


Introduction
Around the second decade of the twentieth century there was speculation about the possibility of cardiac surgery and its possible consequences in the central nervous system.To reduce these potential consequences as much as possible, research was carried out into three different approaches: systemic hypothermia, by placing the patient in a bath of icecold water, cross circulation between two people, and cardiopulmonary bypass (CPB) with a roller pump and an artificial oxygenator (Clau Terré, 2009).Shortly after using these procedures, it became clear there was an advantage provided by the CPB technique with an independent oxygenator and normal systemic flows that neither cross-circulation nor surface hypothermia could provide.It thus became possible to address increasingly complex congenital heart disease and ventricular septal defects, tetralogy of Fallot and other more complex examples.With the introduction of CPB, early neurological complications such as coma, cognitive impairment, strokes, etc. began to appear.

Changes in cerebral blood flow during CPB with extracorporeal pump
The brain weighs about 2% of total body weight.Cerebral blood flow accounts for 10 to 15% of cardiac output.Cerebral blood flow in normothermia is 50 millilitres (ml)/100 grams (g) of tissue per minute (min) and oxygen consumption is 3.5 ml/100 g tissue / min.Cerebral circulation is unusual in its self-regulating ability performed through the arteries of medium and large size.The ability for self-regulation acts at between 50 and 155 millimetres of mercury (mm Hg) for systolic blood pressure in normal conditions, but below 50 mm Hg brain irrigation is directly dependent on the amount of flow to this area.In cases of severe hypertensive disease or cerebral vascular disease, the lower limits can be much higher (Sotaniemi et al., 1986, Caplan et al., 1999).At normothermia, there is permanent neurological damage when there is a cerebral perfusion defect or flow is less than 125 ml/min for more than 7 minutes.Vascular territories with little reserve, such as the border zones of cerebral arteries, the spinal cord and basal ganglia are the most sensitive and most affected by a situation of ischemia.The hippocampal cells and cerebellar Purkinje cells are also particularly sensitive to ischemia.Fig. 2. Cannulation in ascending aorta and right atrium in preparation for using cardiopulmonary bypass.Similarly, the coronary sinus is cannulated to administer cardioplegic solution The average cerebral blood flow in adult CPB is 25 ml/100g/min, which is approximately 6% of systemic flow.The ability for self-regulation with normotension persists, even in cases of hypothermia, ranging between 50 and 155 mm Hg.A decrease below 40 mm Hg may cause a significant decrease in cerebral oxygen delivery.

Etiological classification of neurological complications
The series that we can see in the bibliography show that there is a greater number of NCs in valve replacement surgery than in coronary artery bypass grafting, with an incidence of stroke or transient ischemic attack of 1.7% in patients undergoing coronary artery bypass grafting, 3.6% in those with a simple valve replacement, 3.3% in those undergoing both procedures and 6.7% in those who undergo a multiple valve replacement (Boeken et al., 2005) The NCs in these patients may affect the brain, the spinal cord and peripheral nerves, and the most common of these are often strokes, anoxic-ischemic encephalopathy, epilepsy and brachial plexus injuries Among the many threats to which the Nervous System is subjected during cardiovascular surgery, we can highlight the following: embolism, CPB, general anaesthetics, hypothermia, aortic clamping, and in some cases circulatory arrest.(Mills, 1995;Roach et al., 1996;Hallow et al, 1999).According to the guidelines of the American College of Cardiology / American Heart Association as regards heart surgery for 1999, neurological complications are classified as type I deficiency, including focal lesions such as stroke and stupor or coma, and type II when intellectual functioning and memory are affected, and seizures.However, there are intermediate forms that are difficult to classify (Roach et al., 1996).Strokes or cerebrovascular accidents are on the whole 80% ischemic and 20% hemorrhagic (use of anticoagulants).50% of the ischemic ones are usually caused by atherothrombotic reasons, 25% are lacunar (associated with chronic arterial high blood pressure), 20% are cardioembolic, and the remaining 5% involve the ones we usually include in cardiac surgery: heart attacks in the border zone area between the anterior cerebral artery and the middle cerebral artery (called man-in-the-barrel syndrome due to its clinical consequences), and between the latter and the posterior cerebral artery.(Sanz et al., 2008) In cardiac surgery, the incidence of stroke ranges from 0.7 to 3.8% when assessed retrospectively or between 4.8 to 5.2% if assessed prospectively (Bocerius, 2004).This is the main cause of morbidity in people undergoing cardiac surgery.Its frequency is 5% higher in patients with valvular disease, either due to an increased frequency of atrial fibrillation in these cases or because the valve surgery requires opening the heart chambers and increases the likelihood of air embolization, unlike in coronary surgery.It may appear early on, occurring during surgery, and become apparent when the patient awakes, or later after normal awakening with no focal neurological damage apparent.Both the early and late kinds have a high hospital mortality of 41% and 13% respectively.(Hogue et al, 1999).Strokes cause major disability and high rehabilitation costs because these patients most often require the use of different technical aids or orthotics for walking, wheelchairs, adaptation of their home due to architectural barriers, help from third parties and in some cases the everyday need for health care staff, requiring admission to specialised homes.Martin C et al, 2007) Encephalopathy is usually secondary to a diffuse cerebral injury, and is believed to originate from multiple microembolic events or hypoperfusion (Jacobs et al, 1998).This clinical situation manifests itself in various ways, but it is diagnosed as a state of global impairment of cognitive functions, a reduced level of consciousness that is sometimes prolonged, hallucinations, and increased or decreased psychomotor activity.Its incidence ranges from 3 to 12% and though it involves high mortality (7.5%) this is usually lower than that of a stroke, and has an average hospital stay double that of the usual stay.Encephalopathy in these patients may be metabolic (disorders in the internal environment), pharmacological (drug toxicity), hypoxic ischemic (hypotension) or due to multiple causes (the aforementioned ones plus sepsis, use of balloon counterpulsation).Epilepsy usually occurs as a result of diffuse encephalopathy, a stroke, and in patients with previous epilepsy, and is usually related to the presence of metabolic disorders (generalized epilepsy) or a structured lesion (focal epilepsy).It occurs in 0.3 and 10% of cases and does not often lead to epilepsy.Effects on the spinal cord are usually diagnosed by the appearance of paraparesis in connection with a spinal cord infarction related to hypotension in the border zone or clamping of the aorta.The effects appear most often in reconstructive aortic aneurysms, dissections or traumatic rupture, as well as in valve repairs and the use of intra-aortic balloon counterpulsation.The most common injuries to the Peripheral Nervous System are brachial plexus neuropathy, recurrent laryngeal nerve injury and phrenic nerve injury, almost all related to compression neuropathy of a mechanical nature, due to fracture of the first rib by excessive intraoperative traction exerted on the sternum and chest wall.
-Brachial plexus trauma injury is related to trauma during jugular cannulation, plexus stretching and during the dissection of the internal mammary artery that requires extreme retraction of the chest wall.The incidence ranges between 2.6 and 13%.Most of the deficits are usually transient.(Benecke et al, 1988).-Phrenic nerve injuries are usually related to local hypothermia for myocardial protection (Beran et al, 2008).-Injuries to the radial or ulnar nerve are usually associated with puncturing or hematoma when cannulating arteries for intraoperative pressure monitoring.-Recurrent laryngeal nerve injuries occur in surgery affecting the convexity of the aortic arch.

-
The facial nerve is usually affected by hypothermia or direct mechanical injury.-Peroneal nerve compression resulting from incorrect and prolonged support of the fibular head on a hard surface.We must rule out other types of polyneuropathy such as ICU, produced by malnutrition or deficits such as phosphorus.Extrapyramidal system damage: especially choreoathetosis, whose frequency ranges from 1-12% of patients with neurological complications.This is most often associated with hypothermia and total cardiac arrest.It appears between the 2 nd and 6 th days after surgery and usually decreases in intensity over time, although it may leave significant hypotonia.Neuropsychological disorders: these are assessed by means of memory, intelligence, visual acuity and motor tests.Diffuse disorders can appear in up to 80% of cases in the immediate postoperative period and up to 20-40% still persist two months after surgery.They are more common at older ages.They appear as the patient's subjective sensation of loss of concentration, alertness, memory, learning etc. (Asenbaum et al, 1991;Bendszus et al, 2002).Table 1 shows a summary of the most common complications in cardiac surgery in general.

Prevention of neurological damage in aortic valve surgery
Identifying patients at high risk of neurological damage is as important as the techniques to prevent it.Pre-operative prevention: achieving adequate metabolic control, especially in hypertensive and diabetic patients, optimizing treatment for each patient (antihypertensive, anti-anginal), hemodynamic stabilisation and prevention of the patient's previous arrhythmias, and attempting to reduce postoperative atrial fibrillation.It is also important to carry out a prophylaxis to minimise perioperative stress through suitable information for the patient on the surgery they are to undergo.
Intraoperative prevention: the possibility of embolisation is the main cause of postoperative stroke, especially as regards the ascending aorta's atheromatous plaques, so it is important to conduct a pre-and post-operative transesophageal echocardiography to diagnose these plaques.In this way one can locate and change the cannulation site, location and type of clamping.Another region from which the embolisations come is the left atrial appendage, above all the flap, and the risk of embolisation here may be reduced by ligature of the same.
In valve surgery, delicate mobilization of the heart is particularly important as well as adequate purging of the cavities.CPB may cause injury to the central nervous system in various ways: it is a cause of embolism and a stimulus for the activation of systemic inflammatory response.This is why membrane oxygenators are used, as well as arterial line filters and smaller circuits coated with heparin.These circuits also attempt to maintain the functioning of platelets, preventing the formation of procoagulants, fibrinolysis, reducing bleeding and the need for transfusion.
Proper control of temperature is important (avoiding cerebral hyperthermia), metabolic control and correctly maintaining the acid-base status so as not to increase the possibility of neurological effects.
Cerebral hypoperfusion may reduce purging of microemboli, thereby encouraging neighbouring infarcts.This is why hemodynamic stability should be maintained throughout the surgery.Although autoregulation of cerebral blood flow during cardiopulmonary bypass occurs within a wide range of pressures, hypertensive and diabetic patients may require higher average pressures to maintain perfusion (90 mm Hg).Therefore, although the optimal level is not firmly established, one attempts to apply more pressure than usual to reduce neurological damage in high-risk patients.
Non-CPB surgery does not remove medical complications since the inflammatory response is also triggered, though to a lesser degree.This is associated with a relative reduction in the risk of stroke by 50%.
It is important to try to avoid haematomas on the central or peripheral vascular accesses and pressure zones in order to decrease potential injury to the peripheral nervous system.Post-operative prevention: metabolic control should be continued as regards blood glucose and adequate oxygenation, and anticoagulation and antiagregation should be started immediately.Arrhythmias should be avoided as much as possible, especially atrial fibrillation, usually by using beta blockers.One should continue avoiding zones of compression or of excessive pressure in order to decrease injury to the peripheral nervous system.It is very important at this stage to control all that has been mentioned above since all of this may prolong the time in intensive care units, possibly leading to polyneuropathy in the critical patient with a pattern of axonal damage that would cause long-term consequences similar to those caused by the side effects of a stroke.It is therefore important to get the patient to sit up as soon as possible.

Rehabilitation treatment for neurological complications after aortic valve surgery
The rehabilitative treatment for NCs arising from aorta surgery ranges from prevention of possible complications to restoring the motor control of walking, improving limb functions and increasing the patient's participation in and return to daily life.
In patients with stroke and severe postoperative NCs, rehabilitation treatment in the acute phase is: -Reducing respiratory complications such as atelectasis, retention of secretions, respiratory infections, pleural effusions or those generated by phrenic nerve palsy causing paresis or diaphragmatic paralysis.In any patient on whom a median sternotomy or thoracotomy is performed, active and passive chest physiotherapy protocols are carried out.These patients are protected with a sternal compression vest to avoid pain with the movements induced by Valsalva manoeuvres such as coughing.
A technique of expectoration, chest expansion, postural drainage and chest vibrations could be added to techniques such as incentive spirometry and airflow acceleration techniques.
The typical respiratory pattern of patients undergoing median sternotomy is: low tidal volume, high respiratory rate, absence of sighing, restrictive pattern [reduced vital capacity, reduced inspiratory capacity and reduced functional residual capacity produced by both anesthesia (18%) and decubitus (30%)].Apart from altering the exchange of gases, it is also beneficial in that there are cases where there is aspiration as this decreases mucociliary activity, decreases cough reflex, and produces a hyperreactive and altered alveolar surfactant.An NC was defined as the occurrence of a cerebrovascular accident (STROKE) (ischemic or hemorrhagic), transient ischemic attack (TIA), spinal cord injury, peripheral neuropathy, seizure, stupor, coma, polyneuropathy of critically ill patient, dementia, acute delirium or encephalopathy.A comparative analysis was carried out on the incidence of NCs according to a series of preoperative and postoperative clinical variables: arterial hypertension, diabetes mellitus, dyslipidemia, chronic obstructive pulmonary disease, heart failure, renal failure, prior STROKE, smoker, drinker, calcified valves, endocarditis, peripheral arterial disease, previous revascularization, aortic atherosclerosis, acute myocardial infarction within 3 months prior to surgery, left ventricle ejection fraction, aortic clamping time and CPB time, postoperative arrhythmia, number of transfusions required, whether resuscitation techniques were required, drugs the patients were taking, surgical priority (scheduled, priority and urgent) and type of surgery performed.An attempt was made to determine which of these variables was more important statistically in relation to the others.Table 3 shows the percentages of different NCs in Ao valve surgery.The rate of strokes was 1.5%, corresponding to 7 cases.Of these 7 cases, 2 came from the 71 patients who underwent valve replacement + CABG AO (2.8%), 3 were from the 227 patients that underwent single Ao valve replacement surgery (1.3%), one case was from the 72 patients who underwent multiple valve replacement (1.4%) and finally there was one case from the 12 patients who underwent a 2 nd Ao valve replacement (8.3%).Table 4 shows the three most common NCs that have been seen in this study according to the different surgical techniques and the average times for CPB and Ao clamping measured in minutes.
Of the 23 cases of encephalopathy, 17.4% had a metabolic cause, in 56.5% the cause was hypoxic-ischemic and 26% had various causes.Of the strokes, 57.1% were right hemisphere and 42.9% were on the left.There was only one case in which the stroke was haemorrhagic.

Discussion
NCs are still a common cause of morbidity and mortality in postoperative patients who have undergone aortic valve surgery.Although much has been achieved, there are still many issues to resolve.The research is complex because of the many variables to be considered.
Recent neuropsychological studies have shown that over 50% of patients undergoing cardiac surgery suffer brain injury, as evidenced by a CT scan or MRI (Mc Khan et al., 1997;Hallow et al, 1999).
As regards the sex of the patients, the percentages are fairly balanced (57.7% men and 42.3% women), which is a difference compared to other studies where the male sex clearly prevails over females (Hallow et al, 1999).
Our study evaluates the type of technique used in aortic valve surgery, focusing on the paradigm that with strokes as a neurological complication fewer complications have arisen than in other studies (Zabala, 2005).These averages in Ao valve replacement surgery + coronary artery bypass grafting were 2.8% compared to 3.3%, and in patients undergoing single Ao valve replacement they came to 1.3% compared to 3.3%.In the patients who underwent multiple valve replacement the percentage 1.4% as opposed to 6.7%, and finally out of the patients that underwent a 2 nd Ao valve replacement the percentage was 8.3%.(Table 4.) The NCs evident in postoperative aortic surgery are in keeping with the big series: 0.4% for coma, 6.6% for ACS, 1.5% for STROKE and 5% for encephalopathy (Murkin, 1993, Harrison, 1995;Filsoufi et al, 2008), although there are others in which the incidence is higher (Bucerius et al, 2004).
Identifying predictors for NCs is important for understanding the pathogenesis of these complications as well as for developing preventive strategies (Mornals K et al, 1998;Tjang YS et al, 2007).According to the results of our study, the most influential risk factors in the development of intraoperative and postoperative NCs in aortic valve surgery are: arterial hypertension, heart failure, smoking, having a previous stroke, dyslipidemia and atrial fibrillation in this order, with lesser importance attached to COPD, diabetes mellitus, CRF, being a heavy drinker and peripheral arterial disease.The CPB and aortic clamping time is seen to be longer in cases where there is a NC but with no clearly significant relationship.
As regards strokes, we found that 85.7% were ischemic, as in other studies (Zabala, 2005), but the percentages into which the ischemic strokes are usually divided are not what we found in this study.4 were of cardioembolic origin (66.6%), 2 border territory (33.3%) (Man in the Barrel Syndrome) and one lacunar (16.6%), whereas in the recorded literature 50% are usually due to atherothrombotic causes, 25% are lacunar (related to a chronic hypertension), 20% cardioembolic, and there remain 5% in which we most often include border zone infarctions in cardiac surgery.
The aortic valve surgery that proportionately produces the most NCs is 2 nd aortic valve replacement followed by Ao valve replacement + coronary artery bypass grafting, aortic root replacement (Bentall) (17.2%), multiple valve replacement and finally single Ao valve replacement.Table 4.
As for the 22 cases of endocarditis, 50% occurred in single aortic valve replacement, followed by 27.2% in multiple replacement surgery, and 9% in both second valve replacement and aortic arch replacement.Of these 22 cases, 2 of them had a stroke, one an acute confusional syndrome and 3 suffered encephalopathy.11 of them were operated on a valve and 11 on a prosthetic valve.The bacteria that produced it and the complications are similar to other work associated with the incidence of endocarditis (Arauz-Gongora et al, 1998).
The average times for aortic clamping and CPB were 101 and 125.2 minutes respectively.This is somewhat higher in some of the surgeries with more NCs such as in 2 nd valve replacement, followed by multiple valve replacement and aortic arch replacement (Bentall).Table 4.
Overall mortality was 1.7% and in no way associated with cases of stroke, or with patients who suffered acute confusional state.There were, however, two deaths of patients with hypoxi-ischemic encephalopathy and multiple causes.These results are similar to other publications.However, in our work the appearance of a neurological complication did not significantly increase mortality (Redmond et al, 1996).There are groups with no mortality although the number of patients is lower (n=118) (Mutarelli EG et al, 1993).
The length of hospital stay increases dramatically when there are NCs, as evidenced in other works.Table 5.
The data provided in connection with rehabilitation techniques carried out fall far short because many patients were referred to another hospital area in Madrid or another province of Spain and continued the rehabilitation in places near their original home.This study is limited mainly in that it is a retrospective study and this prevents us from knowing the exact time of the onset of the NC and therefore we cannot draw valid conclusions regarding the type of NC, the rehabilitation treatment carried out and the prognosis.

Conclusions
According to the results of our study, cardiovascular aortic valve surgery has similar incidence of postoperative NC when compared with bypass surgery or combined surgeries.The risk factors in order of importance were: a history of arterial hypertension, heart failure, dyslipidemia, having a previous stroke and being a smoker.NCs after aortic valve surgery have been associated with increased morbidity and mortality, with increased hospitalization time and rehabilitation costs, and they thus contribute to decreased quality of life.The incidence of NCs has remained unchanged in recent years, despite increasing age and comorbidity.The improvement in technical advances has contributed to keeping these percentages up.
Although most complications can be associated with cardiopulmonary bypass, other factors are also involved.Identifying high-risk patients may reduce the incidence of complications in high risk groups, but this seems to be a poor prevention strategy.In an increasingly aging population and with a growing number of diseases, prevention strategies should focus on three aspects: firstly, technical improvements in cardiac surgery and cerebral protection, secondly, identifying reliable techniques to assess neuropsychological dysfunction after cardiac surgery, and finally carrying out technical training in rehabilitation to avoid or minimize the side effects as a result of NCs arising from aortic surgery.

Fig. 3 .
Fig. 3. Sagittal cross-section MRI image showing effects firstly on the cortex of both hemispheres of the brain in the superior fronto-parietal regions and bilaterally.Bilateral basal ganglia are also affected, especially in the left thalamus and both heads of the caudate nuclei.Infarction in the border zone.Man in a barrel syndrome -Swallowing, hydration and nutrition: the incidence of dysphagia in strokes is 50% with a high risk of aspiration and pneumonia.Early sitting up is essential.If there are signs of impaired swallowing as tolerance to food increases, liquids should be thickened and if necessary nasogastric tubes should be put in place to avoid choking.In this event, patients should be referred to medical specialists in dysphagia rehabilitation.-Urinary incontinence is common (30-50%) in the early days, due to lack of sphincter control, immobility, communication problems, prior prostate or gynaecological diseases, urinary tract infection and confusional states.The bladder catheter must be removed when possible, because this is usually resolved in the first few days.If it is not resolved, it is necessary to carry out a urodynamic study to determine the exact cause of the incontinence.-5% of stroke cases also present deep vein thrombosis, and pulmonary embolism is the leading cause of death between the 2 nd and 4 th week after the stroke.Early mobilisation and low molecular weight heparin are the two possibilities for prevention.Medium compression stockings are used for patients at high risk of developing this.-Contractures and spasticity: Immobilization in shortened positions is the main mechanism of contracture with limited passive movement.Prevention is based on passive exercises involving the complete joint range of motion and prolonged muscle stretching.If spasticity appears, one may consider using braces to keep up the stretching and functional postures.

Fig. 5 .
Fig. 5. Postural night splint -Early mobilisation: Beginning activities early on such turning over in the bed or transfer to the seated position.Helping to gain control over the trunk in the sitting position as an essential step to the standing position.The patient should use their nonplegic limbs for basic hygiene and begin to resume everyday activities.-Shoulder pain: With stroke, subluxation may appear in the first weeks as a result of the flaccid stage and it may also appear solely due to immobilization.The appearance of

Fig. 6 .
Fig. 6.Different technical aids and ortheses used for hemiplegicsThere follows an analysis of the impact of different NCs in aortic valve surgery, including both early and late complications from 2008 to 2010 in the University Hospital 12 de Octubre (Madrid).The study includes single and multiple aortic valve replacements, aortic valve replacement plus coronary artery bypass grafting and aortic valve replacement plus tube graft due to root aneurysm (techniques: Bentall(Kirali et al, 2002), David (modified)(Forteza et al, 2010) and 2 nd aortic valve replacement).

Table 1 .
Major neurological complications in cardiac surgery

7.1 Definitions used
The ASIA classification provides basic definitions for terms used in the assessment of spinal cord injury (SCI) and describes the neurological examination: A: complete SCI with lack of sensory and motor functions that extends to the sacral segments S4-S5.B: incomplete, with preservation of sensory function below the neurological level of injury, extending to sacral segments S4-S5 with absence of motor function.C: incomplete, with preservation of motor function below the neurological level and more than half of the key muscles below the neurologic level having a muscle grade lower than 3. D: incomplete, with preservation of motor function below the neurological level and more than half of the key muscles below the neurologic level having muscle grade of 3 or more.
-Chronic obstructive pulmonary disease (COPD): a prior history of COPD that has been diagnosed or treated with medication or chest physiotherapy.-Heart failure (CHF): at least one of the following medical history cases must be present: paroxysmal nocturnal dyspnea, pulmonary rales, pulmonary congestion in the chest xray, dyspnea, or ventricular gallop.-Renal failure: serum creatinine greater than 2 mg/dl.-Regular smoker: any person who has smoked tobacco daily, regardless of the amount, for at least the last month.Our country, Spain, is currently among the highest per capita consumers of cigarettes (>2500 cigarettes/person/ year).E: normal.-Key muscle groups: 10 muscle groups that are assessed as part of the spinal cord standardized test (5 on the upper limb and 5 on the lower limb)

Table 2 .
Drugs used by patients with operation on the Ao valve

Table 5 .
D6 D7 Spinal Cord Injury Syndrome and the other was an ASIA C, D7-D8 spinal cord injury syndrome.Both patients were taken to a hospital specializing in spinal cord injury (National Hospital for Paraplegics in Toledo).Overall mortality was 1.7% and in no way associated with cases of stroke, or with patients who suffered acute confusional state.There were, however, two deaths of patients with hypoxi-ischemic encephalopathy and multiple causes.The average time of hospitalization was 18.7 days.Table5specifies the different durations of hospital stay depending on the surgery performed and the most common NCs suffered.Average hospitalization time measured in days in the most common NCs.ACS = Acute confusional stateThe most common risk factors associated with NCs are shown in Table6.As regards rehabilitation for these patients, 97.3% underwent pulmonary rehabilitation before and after surgery, aiming to prevent respiratory complications.43.8% of patients had some type of neurological complication and needed kinesitherapy techniques.3.5% required occupational therapy.1.75% of patients with NCs underwent electrotherapy techniques.During this period, no patient required any type of orthosis and only one of them needed to use a walker at home.