Degree Of Head Elevation Research Articles

The Effects of Head Elevation on Intracranial Pressure, Cerebral Perfusion Pressure, and Cerebral Oxygenation Among Patients with Acute Brain Injury: A Systematic Review and Meta-Analysis.

Head elevation is recommended as a tier zero measure to decrease high intracranial pressure (ICP) in neurocritical patients. However, its quantitative effects on cerebral perfusion pressure (CPP), jugular bulb oxygen saturation (SjvO2), brain tissue partial pressure of oxygen (PbtO2), and arteriovenous difference of oxygen (AVDO2) are uncertain. Our objective was to evaluate the effects of head elevation on ICP, CPP, SjvO2, PbtO2, and AVDO2 among patients with acute brain injury. We conducted a systematic review and meta-analysis on PubMed, Scopus, and Cochrane Library of studies comparing the effects of different degrees of head elevation on ICP, CPP, SjvO2, PbtO2, and AVDO2. A total of 25 articles were included in the systematic review. Of these, 16 provided quantitative data regarding outcomes of interest and underwent meta-analyses. The mean ICP of patients with acute brain injury was lower in group with 30° of head elevation than in the supine position group (mean difference [MD] - 5.58mm Hg; 95% confidence interval [CI] - 6.74 to - 4.41mm Hg; p < 0.00001). The only comparison in which a greater degree of head elevation did not significantly reduce the ICP was 45° vs. 30°. The mean CPP remained similar between 30° of head elevation and supine position (MD - 2.48mm Hg; 95% CI - 5.69 to 0.73mm Hg; p = 0.13). Similar findings were observed in all other comparisons. The mean SjvO2 was similar between the 30° of head elevation and supine position groups (MD 0.32%; 95% CI - 1.67% to 2.32%; p = 0.75), as was the mean PbtO2 (MD - 1.50mm Hg; 95% CI - 4.62 to 1.62mm Hg; p = 0.36), and the mean AVDO2 (MD 0.06µmol/L; 95% CI - 0.20 to 0.32µmol/L; p = 0.65).The mean ICP of patients with traumatic brain injury was also lower with 30° of head elevation when compared to the supine position. There was no difference in the mean values of mean arterial pressure, CPP, SjvO2, and PbtO2 between these groups. Increasing degrees of head elevation were associated, in general, with a lower ICP, whereas CPP and brain oxygenation parameters remained unchanged. The severe traumatic brain injury subanalysis found similar results.

Acute Heart Failure, 90-Day Mortality, and Gravitational Ischemia in the Brain.

During the 90 days following hospitalization for acute heart failure, the ejection fraction and type of discharge medications have been shown in clinical trials to have little effect on mortality. We examined the recent literature addressing brain-related etiologies of sudden death following heart failure. Two mechanisms of sudden unexpected death have been suggested to possibly result from four significant influences on pathophysiology in the brain. The two causes of sudden death are (1) severe cardiac arrhythmia and (2) neurogenic pulmonary edema. They are both mediated through the brainstem autonomic nuclei generally and executed specifically through the dorsal motor nucleus of the vagus nerve. The four significant influences on pathophysiology, all contributing to ischemia in the brainstem autonomic nuclei, are: (1) Hyper-stimulation of neurons in the solitary tract nucleus, increasing their metabolic requirements; (2) Inadequate blood flow at a vascular watershed terminus, perfusing the autonomic nuclei; (3) Additionally decreased blood flow, globally throughout the brain, following vasoconstriction related to relative hyperventilation and decreased pCO2 levels; (4) Gravitational ischemia in the brainstem caused by the weight of the cerebral hemispheres sitting above the brainstem. Changes in head tilt release gravitational ischemia in the brain. There is no specific head position relative to gravity that is considered favorable or unfavorable for an extended period of time, longer than 24 h. Even a small degree of head elevation, used in managing pulmonary congestion, may increase gravitational ischemia in the posterior fossa and brainstem. In this paper, we suggest a new and important research avenue for intervening in cardiac arrhythmias and preventing their occurrence through the non-invasive use of head-tilting and other head repositioning maneuvers. This could potentially help many geriatric patients with heart failure, who have decreased mobility in bed, and who tend to stay in one position longer, thereby increasing gravitational ischemia in the brain.

Optimum Degree of Head Elevation/Reverse Trendelenburg Position for Sinus Surgery: Systematic Review.

This review aims to evaluate the effect of Reverse Trendelenburg Position (RTP) on bleeding and Boezaart score and to determine the optimum degree of head elevation through a systematic review and meta-analysis.Methodology: We conducted a systematic review according to PRISMA guidelines and a literature search was performed on PubMed, Web of Science, Cochrane, Dental and Oral Science, Google scholar and Clinicaltrials.gov and included randomized controlled trials (RCTs) in English language only. We extracted all relevant data and conducted quality assessment using Cochrane risk of Bias tool (Version 2). We also performed quality assessment of the outcomes using GRADE. Meta-analysis for all the outcomes using conducted on RevMan version 5.3. The search identified 629 articles and three RCTs that met our inclusion criteria. Two were included in the meta-analysis. A total of 124 patients were assessed for bleeding during sinus surgery and there was a significant reduction in total blood loss in RTP (10-15°) when compared to horizontal position by 134 ml (Mean Difference (MD): -134.23; 95% confidence interval (CI): -184.13 to -67.27). RTP also had a significant reduction in bleeding per minute by 1.07 ml/min (MD: -1.07; 95%CI: (-1.69 to -0.44), while the Boezaart score was significantly lower in the RTP group (MD: -0.69; 95%CI: -0.94 to -0.43) when compared to horizontal position. Though with limited evidence RTP for ESS reduces total blood loss, blood loss per minute and improves visualization. Further studies are needed to assess the actual impact and optimal degree of head elevation.

Estimation of the head elevation angle that causes clinically important venous air embolism in a semi-sitting position for neurosurgery: a retrospective observational study.

Introduction: The benefits of a sitting position for neurosurgery involving the posterior fossa remain controversial. The main concern is the risk of venous air embolism (VAE). A recent study showed that the rate of VAE was higher when the head was elevated to 45° than when it was elevated to 30°. However, the degree of head elevation that causes clinically important VAE is unclear. The purpose of this study was to estimate the head elevation angle at which the probability of VAE is 50% by using EtCO2 monitoring to detect of VAE. Methods: The anesthesia records of 23 patients who underwent neurosurgery in a sitting position were reviewed retrospectively. Intraoperative ventilation was set to maintain EtCO2 at approximately 38-42 mmHg. The head elevation angle in each case was determined from a photograph taken by the anesthesiologist or brain surgeon. Nineteen of the 23 cases had photographs available that contained a horizontal reference in the background. Seven cases were treated as VAE during the operation. Six of these cases met the criteria for VAE in this study. Data analysis was performed on a total of 18 patients. The angle between the line connecting the hip joint and the shoulder joint and the horizontal reference was obtained by ImageJ software. Logistic regression was performed using the Python programming language to determine the head elevation angle at which the probability of air embolism was 50%. Results: The decision boundary in the logistic regression was 35.7°. This head elevation angle was the boundary where the probability of VAE was 50%. Conclusion: The angle of head elevation that caused clinically important VAE was estimated to be 35.7°.

A randomised comparative study on customised versus fixed sized pillow for tracheal intubation in the sniffing position by Macintosh laryngoscopy.

Background and Aims:The sniffing position has been most commonly used for positioning of the head and neck to facilitate tracheal intubation. However, the optimum degree of head elevation for the optimal laryngeal view is not well studied, especially in non-Western countries. The present study was aimed to compare the use of a fixed height pillow versus a customised pillow (CP) height for head elevation, in terms of glottis visualisation and time required for tracheal intubation.Methods:With research and ethics committee approval from the institute, this randomised study was conducted among patients of both sexes aged 16 years or more and American Society of Anesthesiologists physical Status I to IV. A total of 134 patients were randomly allocated into routinely used fixed-sized pillow (FP) and CP group (to achieve horizontal alignment of external auditory meatus [EAM] and sternal notch). Primary and secondary outcomes were Cormack–Lehane (C–L) grade of glottic visualisation and time required for tracheal intubation, respectively. They were compared using unpaired t-test and Fisher's exact test as applicable; P < 0.05 was considered statistically significant.Results:One hundred and nineteen patients completed the study. Both groups were similar in terms of demographic and external airway measurements. The mean ± standard deviation height of pillow required in Group CP was 6.26 ± 0.97 cm. Group FP had C–L Grade 3 view more often than Group CP (28.33% vs. 13.56%). In patients with modified Mallampati (MMP) Grade ≥3, the C–L grades and time required for intubation were both significantly lower in group CP. The time required for tracheal intubation was significantly lower in group CP (P = 0.04), even though the C–L grades were similar.Conclusion:Customising pillow for head elevation to horizontally align the EAM and the sternal notch gives better glottic visualisation and intubating conditions in patients with higher MMP grades.

Effect of the degree of head elevation on the incidence and severity of venous air embolism in cranial neurosurgical procedures with patients in the semisitting position.

OBJECTIVE The semisitting position of a patient confers numerous advantages in various neurosurgical procedures, but venous air embolism is one of the associated complications of this position. To date, no prospective studies of the relationship between the degree of head elevation and the rate and severity of venous air embolism for patients undergoing a procedure in this position have been performed. In this study, the authors compared changes in the severity of venous air embolism according to the degree of head elevation (30° or 45°) in patients undergoing an elective cranial neurosurgical procedure in the semisitting position. METHODS One hundred patients undergoing an elective infratentorial craniotomy in the semisitting position were included, and each patient was assigned to 1 of 2 groups. In Group 1, each patient's head was elevated 30° during surgery, and in Group 2, each patient's head elevation was 45°. Patients were assigned to their group according to the location of their lesion. During surgery, the standard anesthetic protocol was used with total intravenous anesthesia, and transesophageal echocardiography was used to detect air in the blood circulation. Any air embolism seen on the echocardiography screen was classified as Grade 0 to 4. If multiple events occurred, the worst graded attack was used for statistical analysis. During hemodynamic changes caused by emboli, fluid and vasopressor requirements were recorded. Surgical and anesthetic complications were recorded also. All results were compared statistically, and a p value of < 0.05 was considered statistically significant. RESULTS There was a statistically significant difference between groups for the total rates of venous air emboli detected on transesophageal echocardiography (22.0% [n = 11] in Group 1 and 62.5% [n = 30] in Group 2; p < 0.0001). The rate and severity of air embolism were significantly lower in Group 1 than in Group 2 (p < 0.001). The rates of clinically important venous air embolism (Grade 2, 3, or 4, venous air embolism with decreased end-tidal carbon dioxide levels and/or hemodynamic changes) were 8.0% (n = 4) in Group 1 and 50.0% (n = 24) in Group 2 (p < 0.0001). There was no association between the rate and severity of venous air embolism with patient demographics (p > 0.05). An association was found, however, between the rate of venous air embolism and the type of surgical pathology (p < 0.001); venous embolism occurred more frequently in patients with a meningioma. There were no major surgical or anesthetic complications related to patient position during the postoperative period. CONCLUSIONS For patients in the semisitting position, an increase in the degree of head elevation is related directly to a higher rate of venous air embolism. With a 30° head elevation and our standardized technique of positioning, the semisitting position can be used safely in neurosurgical practice.

What Is the Ideal Head Position for Patients with Large Strokes

Neurointensivists have been greatly interested in the preferred degree of head elevation in patients with raised intracranial pressure (ICP). Elevating

The effect of position on intracranial pressure

The question as to whether the head and trunk of neurosurgery patients should be elevated remains controversial. This question is particularly important when intracranial hypertension is present. Head up position may have beneficial effects on intracranial pressure (ICP) via changes in mean arterial pressure (MAP), airway pressure, central venous pressure and cerebro spinal fluid displacement. However, in some circumstances, head up position may decrease MAP which in turn will result in a paradoxical rise in ICP through autoregulation mechanisms. Therefore, the degree of head elevation has to be titrated by evaluating the most adequate cerebral perfusion pressure (CPP) for each patient by means of transcranial Doppler or measurement of jugular venous blood oxygen saturation. Head elevation above 30 degrees should be avoided in all cases. In most patients with intracranial hypertension, head and trunk elevation up to 30 degrees is useful in helping to decrease ICP, providing that a safe CPP of at least 70 mmHg or even 80 mmHg is maintained. Patients in poor haemodynamic conditions are best nursed flat. CPP is thus the most important factor in assessment and monitoring when considering head elevation in patients with increased ICP.

Pulmonary consequences of carbon dioxide insufflation for laparoscopic cholecystectomies.

Twenty patients having laparoscopic cholecystectomies were studied for changes in thoracic and lung compliance at 5, 10 and 15 mmHg of intra-abdominal pressure. Fifteen mmHg of intra-abdominal pressure decreased the thoracic and the lung static compliance by 49 and 39% respectively. This was unaffected by the degree of head elevation. During the procedure the end-tidal carbon dioxide increased by a mean of 1.6 kPa at 1 h and 2.0 kPa at 2 h. This did not appear to be related to either the mean intra-abdominal pressure or the total volume of carbon dioxide insufflated. The physiological changes and implications for anaesthetic practice are considered.

Position du patient en neurochirurgie

There is still controversy whether neurosurgical patients' head and trunc should be elevated or not, particularly in case of increased intracranial pressure (ICP). Head up position may have beneficial effects on ICP via changes in mean arterial pressure (MAP), airway pressure, central venous pressure and CSF displacement. However, in some circumstances, head up position may decrease MAP, which in turn will result in a paradoxical rise in ICP through autoregulation mechanisms. Therefore, the degree of head elevation has to be titrated by evaluating the most adequate cerebral perfusion pressure (CPP) for each patient by means of transcranial Doppler or measurement of jugular venous blood oxygen saturation. Head elevation above 30° should be avoided in all cases. In most patients with intracranial hypertension, head and trune elevation up to 30° is useful in helping to decrease ICP, providing that a safe CPP of a least 70 mmHg or even 80 mmHg is maintained. Patients in poor haemodynamic conditions are best nursed flat. CPP is thus a most important factor to evaluate and monitor while considering head elevation in patients with increased ICP.

Evaluation of Managements for Severe Head Injury with Transcranial Doppler Ultrasound

The efficacy and limitation of several medical managements for raised intracranial pressure (ICP) were studied in 20 patients of severe head injury by use of transcranial Doppler (TCD) ultrasound. The effects of head elevation (horizontal, 15°, 30° and 45°), hyperventilation, barbiturate and the Sendai cocktail (20% mannitol, phenytoin and viatmin E) were evaluated by measuring blood flow velocity in the middle cerebral artery (MCAFV), ICP, cerebral perfusion pressure (CPP) and cerebrovascular CO2 reactivity. The cerebrovascular CO2 reactivity was investigated by obtaining the K value in the modified Olesen's formula of cerebral blood flow calculation.As the degree of head elevation was increased, there was a gradual decrease in CPP in association with the decrease of MCAFV in 10 patients examined. These changes in CPP and MCAFV were remarkable in patients with lower GCS scores compared to those with higher GCS scores. The K values examined in 9 patients was low when the patient's GCS score were 5 or less. But as the patients GCS scores improved, the K values returned to normal nearly values. Barbiturates and the Sendai cocktail failed to improve raised ICP and also failed to improve raised ICP and reduced MCAFV in all patients whoes MCAFV were as low as 30-40cm/s before these treatments.These results indicate that noninvasive study with TCD ultrasound can provide valuable informations on optimal therapeutic measures in patients with severe head injury.

Cerebral perfusion pressure, intracranial pressure, and head elevation.

Previous investigations have suggested that intracranial pressure waves may be induced by reduction of cerebral perfusion pressure (CPP). Since pressure waves were noted to be more common in patients with their head elevated at a standard 20 degrees to 30 degrees, CPP was studied as a function of head position and its effect upon intracranial pressure (ICP). In 18 patients with varying degrees of intracranial hypertension, systemic arterial blood pressure (SABP) was monitored at the level of both the head and the heart. Intracranial pressure and central venous pressure were assessed at every 10 degrees of head elevation from 0 degree to 50 degrees. For every 10 degrees of head elevation, the average ICP decreased by 1 mm Hg associated with a reduction of 2 to 3 mm Hg CPP. The CPP was not beneficially affected by any degree of head elevation. Maximal CPP (73 +/- 3.4 mm Hg (mean +/- standard error of the mean] always occurred with the head in a horizontal position. Cerebrospinal fluid pressure waves occurred in four of the 18 patients studied as a function of reduced CPP caused by head elevation alone. Thus, elevation of the head of the bed was associated with the development of CPP decrements in all cases, and it precipitated pressure waves in some. In 15 of the 18 patients, CPP was maintained by spontaneous 10- to 20-mm Hg increases in SABP, and pressure waves did not occur if CPP was maintained at 70 to 75 mm Hg or above. It is concluded that 0 degree head elevation maximizes CPP and reduces the severity and frequency of pressure-wave occurrence. If the head of the bed is to be elevated, then adequate hydration and avoidance of pharmacological agents that reduce SABP or prevent its rise are required to maximize CPP.

Changes in superior sagittal sinus pressure in children with head elevation, jugular venous compression, and PEEP.

Air embolism is a potential hazard during craniotomy whenever intracranial venous pressure is subatmospheric. In order to better understand both the risk of air embolism and its treatment in neurosurgical patients, the authors have investigated the relationship of superior sagittal sinus pressure (SSP) to head position in 15 children and examined the effects of both jugular venous compression and positive end-expiratory airway pressure (PEEP) on SSP. Progressive head elevation significantly decreased mean SSP and, in five patients, SSP was less than 0 mm Hg at 90 degrees torso elevation. A PEEP of 10 cm H2O was ineffective in significantly increasing SSP at any degree of head elevation, whereas bilateral internal jugular compression always caused a significant increase in SSP. The authors conclude that children are at risk for venous air embolism when undergoing suboccipital craniectomy in the sitting position because intracranial venous pressure is often subatmospheric when the head is elevated. Furthermore, maintaining PEEP does not appear to be a reliable treatment for increasing SSP, whereas bilateral internal jugular compression is effective.

Cerebral and cardiovascular responses to changes in head elevation in patients with intracranial hypertension.

To establish if an optimum level of head elevation exists in patients with intracranial hypertension, the authors examined changes in intracranial pressure (ICP), systemic and pulmonary pressures, systemic flows, and intrapulmonary shunt fraction with the patient lying flat, and then with the head elevated at 15 degrees, 30 degrees, and 60 degrees. Cerebral perfusion pressure (CPP) was calculated. The lowest mean ICP was found with elevation of the head to 15 degrees (a fall of -4.5 +/- 1.6 mm Hg, p less than 0.001) and 30 degrees (a fall of -6.1 +/- 3.5 mm Hg, p less than 0.001); the CPP and cardiac output were maintained. With elevation of the head to 60 degrees, the mean ICP increased to -3.8 +/- 9.3 mm Hg of baseline, while the CPP decreased -7.9 +/- 9.3 mm Hg (p less than 0.02), and the cardiac index also fell -0.25 +/- 0.28 liters/min/sq m (p less than 0.01). No significant change in filling pressures, arterial oxygen content, or heart rate was encountered at any level of head elevation. Therefore, a moderate degree (15 degrees or 30 degrees) of head elevation provides a consistent reduction of ICP without concomitant compromise of cardiac function. Lower (0 degrees) or higher (60 degrees) degrees of head elevation may be detrimental to the patient because of changes in the ICP, CPP, and cardiac output.