Targeted temperature management in patients with intracerebral haemorrhage, subarachnoid haemorrhage, or acute ischaemic stroke: consensus recommendations.

BACKGROUND: A modified Delphi approach was used to identify a consensus on practical recommendations for the use of non-pharmacological targeted temperature management in patients with intracerebral haemorrhage, subarachnoid haemorrhage, or acute ischaemic stroke with non-infectious fever (assumed neurogenic fever). METHODS: Nine experts in the management of neurogenic fever participated in the process, involving the completion of online questionnaires, face-to-face discussions, and summary reviews, to consolidate a consensus on targeted temperature management. RESULTS: The panel's recommendations are based on a balance of existing evidence and practical considerations. With this in mind, they highlight the importance of managing neurogenic fever using a single protocol for targeted temperature management. Targeted temperature management should be initiated if the patient temperature increases above 37.5°C, once an appropriate workup for infection has been undertaken. This helps prevent prophylactic targeted temperature management use and ensures infection is addressed appropriately. When neurogenic fever is detected, targeted temperature management should be initiated rapidly if antipyretic agents fail to control the temperature within 1 h, and should then be maintained for as long as there is potential for secondary brain damage. The recommended target temperature for targeted temperature management is 36.5-37.5°C. The use of advanced targeted temperature management methods that enable continuous, or near continuous, temperature measurement and precise temperature control is recommended. CONCLUSIONS: Given the limited heterogeneous evidence currently available on targeted temperature management use in patients with neurogenic fever and intracerebral haemorrhage, subarachnoid haemorrhage, or acute ischaemic stroke, a Delphi approach was appropriate to gather an expert consensus. To aid in the development of future investigations, the panel provides recommendations for data gathering.

The internal nasal valve: a validated grading system and operative guide.

PURPOSE: Nasal obstruction is a highly subjective and commonly reported symptom. The internal nasal valve (INV) is the rate limiting step to nasal airflow. A static INV grading score was devised with regard to visibility of the middle turbinate. METHODS: A prospective study of all patients who underwent primary external functional septorhinoplasty in 2017 for nasal obstruction. All patients' INV score was assessed pre- and postoperatively in a blinded and independent fashion by surgeons of varying seniority. RESULTS: Twenty-eight patients were studied, with mean age 30.9 years and follow-up 18.8 weeks. Inter-rater and test-retest reliability of INV grading were excellent, with Cronbach's alpha 0.936 and 0.920, respectively. There was also statistically significant improvement in both subjective and objective postoperative outcome measures including nasal inspiratory peak flows. CONCLUSIONS: We demonstrate a novel, easy to interpret, clinically valuable grading system of the static internal nasal valve that is reliable and reproducible.

Peak nasal inspiratory flow correlates with quality of life in functional endoscopic sinus surgery.

OBJECTIVES: Whilst nasal function and airflow improve subjectively following functional endoscopic sinus surgery (FESS), a clinically useful and objective tool for quantifying such improvement is lacking. The peak nasal inspiratory flow (PNIF) metre offers convenient and objective measures of nasal patency. However, it has not yet been established whether changes in PNIF after surgery reflect changes in subjective disease burden. In this study we aimed to determine whether changes in PNIF correlate with commonly used subjective symptom and quality of life outcome measures following FESS for chronic rhinosinusitis (CRS). DESIGN: Prospective cohort. SETTING: Royal National Throat Nose and Ear Hospital. PARTICIPANTS: Thirty-seven patients undergoing FESS for CRS, with or without polyps (21 male, mean age 48.8). MAIN OUTCOME MEASURES: PNIF, "SNOT-22", "NOSE" and "VAS" questionnaires were performed before and after surgery. RESULTS: In all patients, there was a strong negative correlation between change in PNIF and change in "SNOT-22" score following surgery (Pearson r=-.64, P<.0001). Strong negative correlations were also seen during subgroup analysis of patients with and without polyps (r=-.57, P=.006 and r=-.67, P=.005, respectively). Change in PNIF correlated significantly with change in "NOSE" score following surgery in all patients and those without polyps (r=-.54, P=.0005 and r=-.68, P=.003). There were no significant correlations between PNIF and VAS (nasal obstruction). CONCLUSIONS: Changes in PNIF after FESS appear to best reflect improvements in quality of life in CRS as measured using the "SNOT-22" questionnaire.

Early Changes in Brain Oxygen Tension May Predict Outcome Following Severe Traumatic Brain Injury.

We report on the change in brain oxygen tension (PbtO2) over the first 24 h of monitoring in a series of 25 patients with severe traumatic brain injury (TBI) and relate this to outcome. The trend in PbtO2 for the whole group was to increase with time (mean PbtO2 17.4 [1.75] vs 24.7 [1.60] mmHg, first- vs last-hour data, respectively; p = 0.002). However, a significant increase in PbtO2 occurred in only 17 patients (68 %), all surviving to intensive care unit discharge (p = 0.006). Similarly, a consistent increase in PbtO2 with time occurred in only 13 patients, the correlation coefficient for PbtO2 versus time being ≥0.5 for all survivors. There were eight survivors and four non-survivors, with low correlation coefficients (<0.5). Significantly more patients with a correlation coefficient ≥0.5 for PbtO2 versus time survived in intensive care (p = 0.039). The cumulative length of time that PbtO2 was <20 mmHg was not significantly different among these three groups. In conclusion, although for the cohort as a whole PbtO2 increased over the first 24 h, the individual trends of PbtO2 were related to outcome. There was a significant association between improving PbtO2 and survival, despite these patients having cumulative durations of hypoxia similar to those of non-survivors.

Outcomes in endoscopic sinus surgery: olfaction, nose scale and quality of life in a prospective cohort study.

OBJECTIVES: To determine the efficacy of endoscopic sinus surgery (ESS) on olfactory function in chronic rhinosinusitis patients with nasal polyps (CRSwNP) and without nasal polyps (CRSsNP) and to compare the nasal obstruction and symptom evaluation (NOSE) scale before and after surgery. DESIGN: A prospective cohort study SETTING: Royal National Throat and Nose and Ear Hospital, London UK. PARTICIPANTS: One hundred and thirteen patients with CRS; 60 CRSwNP and 53 CRSsNP. OUTCOME MEASUREMENTS: Olfaction was measured using both the University of Pennsylvania Smell Investigation Test (UPSIT) and the 'sense of smell' visual analogue scale (VAS). The NOSE scale, the sinonasal outcome test (SNOT 22) and the Lund-Kennedy (LK) surgeon reported scores were also measured pre- and postoperatively at 6 months. RESULTS: The UPSIT psychophysical measurement significantly improved following ESS in the CRSwNP subgroup as did the patients perceived VAS sense of smell. However, in the CRSsNP subgroup, the improved VAS and UPSIT measurements were not significant. The NOSE, SNOT 22 and LK scores all improved significantly. The olfactory improvement as measured by the UPSIT correlated to the SNOT-22, but a correlation between the NOSE score and UPSIT was not found. CONCLUSIONS: Endoscopic sinus surgery significantly improved the patient's perceived and measured sense of smell in the CRSwNP subgroup which is the most surgically responsive CRS subgroup. Additionally, improved olfaction in the CRSwNP subgroup is most likely to improve the patient's quality of life. Endoscopic sinus surgery significantly improved the NOSE scale in both CRS subgroups at 6 months following surgery.

The outcome of septorhinoplasty surgery on olfactory function.

OBJECTIVES: To assess olfactory outcomes in patients undergoing septorhinoplasty surgery in our unit. DESIGN: Prospective cohort study. SETTING: The Royal National Throat Nose and Ear Hospital, London. PARTICIPANTS: Forty-three patients undergoing functional septorhinoplasty (Males = 26; mean age = 34.1 ± 12.2) were recruited into the study. MAIN OUTCOME MEASURES: The primary outcome of olfactory function was assessed using 'Sniffin sticks'. Our secondary outcomes were assessment of patient quality of life using the disease specific Sino-nasal Outcome Test-23 questionnaire (SNOT-23) and a visual analogue scale for sense of smell. These measures were repeated at 12 weeks post operatively. RESULTS: There was a significant change in the Sniffin' sticks score post-operatively (8.3 versus 9.6; P < 0.001). The SNOT-23 score also showed a significant improvement post-operatively (53.5 versus 40.4; P < 0.001). A significant improvement was not found in the smell/taste question (question 21) of the SNOT-23 questionnaire as well as the visual analogue scale for sense of smell. A difference in olfactory outcome was not found between open versus closed approaches, primary versus revision surgery and traumatic versus non traumatic cases. CONCLUSIONS: The results show a measured significant improvement in olfaction following functional Septorhinoplasty but not a subjective improvement in the patients perception of their sense of smell and hence not a clinically significant difference. The reasons for the measured improvement are not clear and are likely to be multifactorial.

The need for an objective measure in septorhinoplasty surgery: are we any closer to finding an answer?

OBJECTIVES: To assess the reliability of nasal inspiratory peak flow (NIPF) in providing a clinically accurate objective measure following functional septorhinoplasty by comparing it to the validated disease-specific quality-of-life questionnaire, SNOT-22. Studies so far have demonstrated poor correlation between bilateral NIPF and symptom-specific nasal questionnaires following septorhinoplasty. DESIGN: To perform a prospective comparative analysis between NIPF and the validated disease-specific quality-of-life questionnaire SNOT-22 and to determine whether a correlation exists following septorhinoplasty surgery. SETTING: The Royal National Throat Nose and Ear Hospital, London. PARTICIPANTS: A total of 122 patients (78 males, 44 females; mean age 33.5 ± 12.2 years) were recruited from the senior authors rhinology clinic and underwent functional septorhinoplasty surgery. MAIN OUTCOME MEASURES: Preoperative and postoperative nasal inspiratory peak flow (NIPF) measurements were performed in addition to the completion of three subjective quality-of-life and symptom assessment tool questionnaires; Sinonasal Outcome Test 22 (SNOT-22), Nasal Obstruction Symptom Evaluation (NOSE) and Visual Analogue Scale (VAS: 0-10). RESULTS: The mean preoperative NIPF was 88.2 L/min, and the postoperative value was 101.6 L/min and showed a significant improvement following surgery (P = 0.0064). The mean total SNOT-22 score improved significantly from 48.6 to 26.6 (P < 0.0001); the NOSE score from 14.1 to 6.6 (P < 0.0001); and the Visual Analogue Scale (VAS) blockage score from 6.9 to 3.2 (P < 0.0001). All individual domains assessed showed improvements postoperatively, but no correlation was found between the NIPF and SNOT-22 score. Equally, we did not find a correlation between NIPF and the symptom-specific NOSE questionnaire and the nasal blockage domain on the Visual Analogue Scale (VAS) scale. CONCLUSION: We have demonstrated that NIPF does not correlate with the SNOT-22 disease-specific questionnaire, although both outcomes significantly improve postoperatively. At present, we are still lacking a clinically accurate objective measure of nasal function for the evaluation of patients undergoing septorhinoplasty surgery.

Lessons from rhinology and facial plastic surgery clinical negligence claims in England 2013-2018.

OBJECTIVE: This study reviewed all rhinology clinical negligence claims in the National Health Service in England between 2013 and 2018. METHOD: All clinical negligence claims held by National Health Service Resolution relating to rhinology in England between 1 April 2013 and 1 April 2018 were reviewed. RESULTS: There were 171 rhinology related claims with a total estimated potential cost of £13.6 million. There were 119 closed claims (70 per cent) with a total cost of £2.3 million, of which 55 claims resulted in payment of damages. Over three quarters of all rhinology claims were associated with surgery (n = 132). Claims associated with endoscopic sinus surgery had the highest mean cost per claim (£172 978). Unnecessary pain (33.9 per cent) and unnecessary operation (28.1 per cent) were the most commonly cited patient injuries. CONCLUSION: Patient education and consent have been highlighted as key areas for improvement from this review of rhinology related clinical negligence claims. A shift in clinical practice towards shared decision making could reduce litigation in rhinology.

Forced convective head cooling device reduces human cross-sectional brain temperature measured by magnetic resonance: a non-randomized healthy volunteer pilot study.

BACKGROUND: This pilot study in five healthy adult humans forms the pre-clinical assessment of the effect of a forced convective head cooling device on intracranial temperature, measured non-invasively by magnetic resonance spectroscopy (MRS). METHODS: After a 10 min baseline with no cooling, subjects received 30 min of head cooling followed by 30 min of head and neck cooling via a hood and neck collar delivering 14.5 degrees C air at 42.5 litre s(-1). Over baseline and at the end of both cooling periods, MRS was performed, using chemical shift imaging, to measure brain temperature simultaneously across a single slice of brain at the level of the basal ganglia. Oesophageal temperature was measured continuously using a fluoroptic thermometer. RESULTS: MRS brain temperature was calculated for baseline and the last 10 min of each cooling period. The net brain temperature reduction with head cooling was 0.45 degrees C (SD 0.23 degrees C, P=0.01, 95% CI 0.17-0.74 degrees C) and with head and neck cooling was 0.37 degrees C (SD 0.30 degrees C, P=0.049, 95% CI 0.00-0.74 degrees C). The equivalent net reductions in oesophageal temperature were 0.16 degrees C (SD 0.04 degrees C) and 0.36 degrees C (SD 0.12 degrees C). Baseline-corrected brain temperature gradients from outer through intermediate to core voxels were not significant for either head cooling (P=0.43) or head and neck cooling (P=0.07), indicating that there was not a significant reduction in cooling with progressive depth into the brain. CONCLUSIONS: Convective head cooling reduced MRS brain temperature and core brain was cooled.

Similarity between the suprasystolic wideband external pulse wave and the first derivative of the intra-arterial pulse wave.

BACKGROUND: Wideband external pulse (WEP) monitoring, using a broad bandwidth piezoelectric sensor located over the brachial artery under the distal edge of a sphygmomanometer cuff, can be used for evaluating the contour of the arterial pressure pulse wave. The pulse contour contains valuable information relating to cardiovascular function which may be of clinical use in addition to blood pressure measurements. The aim of this study was to compare the shape of the WEP signal during inflation of the cuff to suprasystolic pressure, with intra-arterial pressure waves, after the administration of vasoactive drugs. METHODS: Radial intra-arterial and suprasystolic WEP waveforms were recorded in 11 healthy men (mean 23 yr) before and at the end of infusion of glyceryl trinitrate, angiotensin II, norepinephrine, and salbutamol. Waveform similarity was assessed by comparing the timing and pressure of incident and reflected waves and by root mean square error (RMSE). RESULTS: The WEP signal was found to closely resemble the first derivative of intra-arterial pressure. The WEP signal could be used to derive an arterial pressure wave with minimal bias in the timing of incident [- 8 (18) ms, mean (SD)] and reflected [- 1 (24) ms] waves. Augmentation index was underestimated by WEP [- 7 (18)%]. WEP also provided a measure of compliance which correlated with pulse wave velocity (r = - 0.44). RMSE values after the administration of each of the four drugs mentioned earlier were 12.4 (3.8), 17.7 (5.0), 22.1 (11.7), and 28.9 (22.4) mm Hg, respectively. Changes in derived WEP signals were similar to those measured by arterial line with all drugs. CONCLUSIONS: The suprasystolic WEP signals can be used to derive arterial pressure waves which, although not identical, track changes in the intra-arterial pulse wave induced by vasoactive drugs.

Prophylactic vs postoperative antibiotic use in complex septorhinoplasty surgery: a prospective, randomized, single-blind trial comparing efficacy.

OBJECTIVE: To compare the efficacy of prophylactic vs postoperative antibiotic use in complex septorhinoplasty and strengthen the evidence base for antibiotic use in nasal surgery. DESIGN: A randomized, prospective, single-blinded trial. One hundred sixty-four patients requiring complex septorhinoplasty surgery were recruited sequentially from the waiting lists of the 2 senior authors. Power was calculated at 80% at the 5% significance level. Patients randomized to the prophylactic arm of the study received three 1200-mg intravenous doses of amoxicillin-clavulanate, given at induction of anesthesia and at 6 and 12 hours postoperatively. Patients in the postoperative antibiotic arm received a 7-day course of 375 mg of amoxicillin-clavulanate 3 times a day. Patients allergic to penicillin were given erythromycin. Clinical and microbiological evidence of infection on the 10th postoperative day was categorized as either minor (vestibulitis) or major (nasal or septal cellulitis, septal abscess, secondary hemorrhage, or donor-site infection) infections. RESULTS: At follow-up, 6 (7%) of 82 patients in the prophylactic arm and 9 (11%) of 82 of patients in the postoperative arm showed evidence of infection. Most (80%) of infections were minor. There was no significant difference in infection rates between the prophylactic and postoperative arms on chi2 analysis (P = .42). All 164 patients completed the study on an intention-to-treat basis. CONCLUSION: We recommend the use of prophylactic antibiotics rather than empirical postoperative antibiotics for patients undergoing complex septorhinoplasty.

Quantification of secondary CPP insult severity in paediatric head injured patients using a pressure-time index.

This paper describes and validates a new Cumulative Pressure-Time Index (CPT) which takes into account both duration and degree of cerebral perfusion pressure (CPP) derangement and determines critical thresholds for CPP, in a paediatric head injury dataset. Sixty-six head-injured children, with invasive minute-to-minute intracranial pressure (ICP) and blood pressure monitoring, had their pre-set CPP derangement episodes (outside the normal range) identified in three childhood age-bands (2-6, 7-10, and 11-16 years) and global outcome assessed at six months post injury. The new cumulative pressure-time index more accurately predicted outcome than previously used summary measures and by varying the threshold CPP values, it was found that these physiological threshold values (< or = 48, < or = 52 and < or = 56 mmHg for 2-6, 7-10, and 11-16 years respectively) best predicted brain insult in terms of subsequent mortality and morbidity.

Beta/Gamma EEG activity in patients with primary and secondary insomnia and good sleeper controls.

STUDY OBJECTIVE: Several studies have shown that patients with insomnia exhibit elevated levels of Beta EEG activity (14-35 Hz) at or around sleep onset and during NREM sleep. In this study, we evaluated 1) the extent to which high frequency EEG activity is limited to the 14-32 Hz domain, 2) whether high frequency EEG activity (HFA) is associated with discrepancies between subjective and PSG measures of sleep continuity, and 3) the extent to which high frequency EEG activity occurs in patients with primary, as opposed to secondary, insomnia. DESIGN: Three groups (n=9 per group) were compared: Primary Insomnia, Insomnia secondary to Major Depression, and Good Sleeper Controls. Groups were matched for age, sex and body mass. Average spectral profiles were created for each NREM cycle after removing waking and movement epochs and epochs containing micro- or mini-arousals. SETTING: Sleep Research Laboratory PATIENTS OR PARTICIPANTS: Patients with primary and secondary insomnia INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Subjects with Primary Insomnia exhibited more average NREM activity for Beta-1 (14-20Hz), Beta-2 (20-35Hz) and Gamma activity (35-45Hz) than the other two groups (p.<.01). Group differences were also suggestive for Omega activity (45.0-125Hz) (p.<.10), with MDD subjects tending to exhibit more activity than the other groups. Correlational analyses revealed that average NREM Beta-1 and Beta-2 activity tended to be negatively correlated with subjective-objective discrepancy measures for total sleep time and sleep latency. CONCLUSIONS: Our results confirm that Beta activity is increased in Primary Insomnia. In addition, our data suggest that high frequency activity in patients with Primary Insomnia is limited to the Beta/Gamma range (14-45 Hz), and is negatively associated with the perception of sleep.

Cerebrovenous oxygen saturation monitoring: practical considerations and clinical relevance.

Measurement of the saturation of brain effluent blood gives a global estimate of cerebral oxygenation. It may provide clinicians with information to assist in reducing secondary insults to the brain with potential benefits to a range of patients with actual or potential acute brain injury such as trauma and cardiac bypass procedures. The technology to continuously measure this variable is simple to use but requires attention to detail; it is limited in its ability to detect discrete regions of ischaemia or hyperaemia unless these are of sufficient magnitude to influence the saturation of brain effluent blood. There are few complications that result from this invasive technique and they are usually of a minor nature. The technique also enables research opportunities from the ability to sample blood as it leaves the cranium. Poor outcomes are seen in patients with traumatic brain injury who exhibit either reduced or increased cerebrovenous oxygen saturation and it remains to be seen if detection and correction of these anomalies will produce patient benefits.

Effect of deprivation and gender on the incidence and management of acute brain disorders.

OBJECTIVE: To determine the impact of deprivation and gender on the incidence and emergency management of acute brain disorders. DESIGN: Retrospective database review of mortality, hospital discharge, and ICU discharge data. SETTING: Lothian Health Board area, 1995-1999. PATIENTS AND PARTICIPANTS: All persons over the age of 15 dying or being discharged from hospital with a primary diagnosis of stroke, epilepsy, subarachnoid haemorrhage (SAH) or traumatic brain injury; patients registered in the Scottish Intensive Care Society Audit Database as having been discharged from the supraregional neurosciences intensive care unit with one of these as a primary diagnoses and a home postcode within the Lothian Health Board area. MEASUREMENTS AND RESULTS: Standardised ratios were calculated for hospital admission, mortality, and ICU admission by deprivation category and gender. Data were available for 29,205 hospital admissions, 5,227 deaths, and 360 ICU admissions. For all diagnoses, deprivation was associated with higher rates of hospital admission and death. Deprivation was associated with lower rates of ICU admission for traumatic brain injury and stroke. There was a U-shaped relationship between deprivation and ICU admission with epilepsy. There were no gender differences in rates of ICU admission. Males had higher rates of hospital admission for all conditions and of death from epilepsy and SAH, and lower rates of death from stroke. CONCLUSIONS: We have demonstrated deprivation- and gender- differences in the incidence and emergency management of four acute brain disorders. The identification of the source(s) of these differences is an important subject for further research.

Pulmonary and cardiac sequelae of subarachnoid haemorrhage: time for active management?

Cardiac injury and pulmonary oedema occurring after acute neurological injury have been recognised for more than a century. Catecholamines, released in massive quantities due to hypothalamic stress from subarachnoid haemorrhage (SAH), result in specific myocardial lesions and hydrostatic pressure injury to the pulmonary capillaries causing neurogenic pulmonary oedema (NPO). The acute, reversible cardiac injury ranges from hypokinesis with a normal cardiac index, to low output cardiac failure. Some patients exhibit both catastrophic cardiac failure and NPO, while others exhibit signs of either one or other, or have subclinical evidence of the same. Hypoxia and hypotension are two of the most important insults which influence outcome after acute brain injury. However, despite this, little attention has hitherto been devoted to prevention and reversal of these potentially catastrophic medical complications which occur in patients with SAH. It is not clear which patients with SAH will develop important cardiac and respiratory complications. An active approach to investigation and organ support could provide a window of opportunity to intervene before significant hypoxia and hypotension develop, potentially reducing adverse consequences for the long-term neurological status of the patient. Indeed, there is an argument for all SAH patients to have echocardiography and continuous monitoring of respiratory rate, pulse oximetry, blood pressure and electrocardiogram. In the event of cardio-respiratory compromise developing i.e. cardiogenic shock and/or NPO, full investigation, attentive monitoring and appropriate intervention are required immediately to optimise cardiorespiratory function and allow subsequent definitive management of the SAH.

The role of endothelin-1 in pressure autoregulation of cerebral blood flow in rats.

OBJECTIVE: To investigate the role of the endothelin system in pressure autoregulation of cerebral blood flow (CBF) in rats. DESIGN: We tested pressure autoregulation by increasing cerebral perfusion pressure (CPP; mean arterial pressure-intracranial pressure) with norepinephrine (0.08 microgram.kg-1.min-1 for 30 min) twice in ten anesthetized normocapnic rats. The first test was performed without (control test) and the second test after administration of the combined endothelin ETA/B receptor antagonist, bosentan, i.v. (30 mg/kg; drug test). CBF was measured by the hydrogen clearance technique. RESULTS: During the control test, norepinephrine infusion increased CPP by 21 +/- 2 (23 +/- 2%) mmHg (mean +/- SEM; p < 0.001) and CBF by 3.6 +/- 3.1 (6 +/- 8%) ml/100 g/min (p = 0.5, Fig. 1); during the drug test, norepinephrine infusion increased CPP by 18 +/- 1 (20 +/- 2%) mmHg (p < 0.001) and CBF by 15.8 +/- 4.1 (46 +/- 13%) ml/100 g/min (p = 0.004). Mean arterial pressure was not affected by bosentan infusion (p = 0.2). PaCO2 levels were stable during the tests (40.2 +/- 1.4 mmHg). CONCLUSIONS: The endothelin system is involved in cerebral pressure autoregulation in a rodent model in vivo. The role of this system under pathophysiologic conditions such as subarachnoid hemorrhage, where basal vascular tone and its regulation may be altered, remains to be defined.

Cerebral blood flow and metabolism in severe brain injury: the role of pressure autoregulation during cerebral perfusion pressure management.

OBJECTIVE: To ascertain if norepinephrine can be used as part of the cerebral perfusion pressure (CPP) management to increase arterial blood pressure (MAP) without causing cerebral hyperemia after severe head injury (HI). DESIGN: Prospective, interventional study. SETTING: Intensive care unit in a university hospital. PATIENTS: Twelve severely HI patients; median Glasgow Coma Scale was 6 (range 3-8). INTERVENTIONS: CPP management ( = 70 mmHg). Pressure autoregulation (assessed by norepinephrine infusion) was defined intact if % CPP/%CVR < or = 2. RESULTS: Cerebral blood flow (CBF: Xe133 inhalation technique), jugular bulb oxygen saturation (SjO2) and transcranial Doppler (TCD) were recorded during the test. Norepinephrine increased CPP by 33 % (+/- 4). Autoregulation was found to be intact in ten patients and defective in two. In the ten patients with preserved autoregulation, CBF decreased from 31 +/- 3 to 28 +/- 3 ml/ 100 g/min; in the two patients with impaired autoregulation CBF increased respectively from 16 to 35 and from 21 to 70 ml/100 g/min. SjO2 did not change significantly from baseline. TCD remained within the normal range. CONCLUSIONS: During CPP management norepinephrine can be used to increase MAP without potentiating hyperemia if pressure autoregulation is preserved. The assessment of pressure autoregulation should be considered as a guide for arterial pressure-oriented therapy after HI.

Multimodality monitoring as a guide to treatment of intracranial hypertension after severe brain injury.

Transcranial doppler measurements of blood flow velocity in the middle cerebral artery were made during treatment of raised intracranial pressure (ICP) in 22 patients with severe brain injury. Twenty patients also had continuous measurement of arterial and jugular bulb venous oxygen saturation (SJO2). The transcranial Doppler parameters studied included both mean flow velocity and pulsatility index (PI). Successful treatment was defined as a reduction of ICP to less than 20 mm Hg with improvement or preservation of cerebral perfusion pressure (CPP) above 60 mm Hg. Successful therapy was associated with a significant rise in SJO2 and reduction of cerebral arteriovenous oxygen content difference (AVDO2) and PI only when the pretreatment CPP was less than 60 mm Hg. An increase in CPP beyond 70 mm Hg did not further improve cerebral oxygen delivery and PI, suggesting that autoregulation became a factor above this CPP threshold. Treatment failure during administration of hypnotic drugs resulted in a reduction in arterial pressure, CPP, SJO2, and mean velocity and in an increase in PI and AVDO2, despite a decrease in ICP. CPP is the most important parameter to monitor during ICP therapy. It should be maintained above 70 mm Hg in patients with severe brain injury.

Accuracy of a miniature intracranial pressure monitor, its function during magnetic resonance scanning, and assessment of image artifact generation.

OBJECTIVE: We examined the accuracy and repeatability of an intracranial pressure (ICP) monitor (Codman MicroSensor; Johnson & Johnson Professional, Inc., Raynham, MA) in a nonmagnetic environment and during magnetic resonance imaging (MRI). The resulting image artifact generation was calculated. ICP monitoring is essential in management of severe head injury, but few ICP monitoring devices are compatible with use in an MRI scanner. The use of MRI to assess head injury is increasing, and developing safe methods of continuously monitoring ICP may improve patient care. METHODS: A water manometer was used as the standard for comparison. We assessed pressure readings from the ICP monitor in a nonmagnetic environment using a standard and a long connector cable between the pressure transducer and display unit. This long cable permitted testing during MRI sequences because the display unit could be distanced from the magnet. Accuracy was determined during T2-weighted imaging, proton spectroscopy, and diffusion-weighted imaging, and artifact generation was assessed. RESULTS: We found a high degree of accuracy for repeated measurements over a clinical pressure range using both standard and long connector cables outside the MRI room. During MRI scanning, the ICP monitor was accurate during T2 and proton spectroscopy sequences. Accuracy during diffusion-weighted imaging, however, was clinically unacceptable. This ICP monitor creates a reduction in signal-to-noise ratio in the received signal during T2-weighted imaging and proton spectroscopic imaging, with the obtained images still radiologically interpretable. CONCLUSION: The Codman ICP monitor is sufficiently accurate and free of artifact generation to be used during most clinical MRI applications. This could enhance patient monitoring and safety.