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1.
Neurocrit Care ; 2024 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-38664328

RESUMO

INTRODUCTION: The use of continuous positive airway pressure has been shown to improve the tolerance of the apnea test, a critical component of brain death evaluation. The ability to deactivate the apnea backup setting has made apnea testing possible using several conventional mechanical ventilators. Our goal was to evaluate the safety and efficacy of apnea testing performed on mechanical ventilation, compared with the oxygen insufflation technique, for the determination of brain death. METHODS: This was a retrospective study. In 2016, our institution approved a change in policy to permit apnea testing on conventional mechanical ventilation. We examined the records of consecutive adults who underwent apnea testing as part of the brain death evaluation process between 2016 and 2022. Using an apnea test technique was decided at the discretion of the attending physician. Outcomes were successful apnea test and the occurrence of patient instability during the test. This included oxygen desaturation (SpO2) < 90%, hypotension (mean arterial pressure < 65 mm Hg despite titration of vasopressor), cardiac arrhythmia, pneumothorax, and cardiac arrest. RESULTS: Ninety-two adult patients underwent apnea testing during the study period: 58 (63%) with mechanical ventilation, 32 (35%) with oxygen insufflation, and 2 (2%) lacked documentation of technique. Apnea tests could not be completed successfully in 3 of 92 (3%) patients-two patients undergoing the oxygen insufflation technique (one patient with hypoxemia and one patient with hypotension) and one patient on mechanical ventilation (aborted for hemodynamic instability). Hypoxemia occurred in 4 of 32 (12.5%) patients with oxygen insufflation and in zero patients on mechanical ventilation (p = 0.01). Hypotension occurred during 3 of 58 (5%) tests with mechanical ventilation and 4 of 32 (12.5%) tests with oxygen insufflation (p = 0.24). In multivariate analysis, the use of oxygen insufflation was an independent predictor of patient instability during the apnea test (odds ratio 37.74, 95% confidence interval 2.74-520.14). CONCLUSIONS: Apnea testing on conventional mechanical ventilation is feasible and offers several potential advantages over other techniques.

2.
Crit Care ; 16(3): R79, 2012 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-22578001

RESUMO

INTRODUCTION: Optic nerve sheath diameter (ONSD) measurement with bedside ultrasound has been shown in many studies to accurately detect high intracranial pressure (ICP). The accuracy of point-in-time ONSD measurement in the presence of ongoing fluctuation of ICP between high and normal is not known. Recent laboratory investigation suggests that reversal of optic nerve sheath distension may be impaired following bouts of intracranial hypertension. Our objective was to compare the accuracy of ONSD measurement in the setting of fluctuating versus stable ICP. METHODS: This was a retrospective analysis of data from prospective study comparing ONSD to invasive ICP. Patients with invasive ICP monitors in the ICU underwent ONSD measurement with simultaneous blinded recording of ICP from the invasive monitor. Three measurements were made in each eye. Significant acute ICP fluctuation (SAIF) was defined in two different ways; as the presence of ICP both above and below 20 mmHg within a cluster of six measurements (Definition 1) and as a magnitude of fluctuation >10 mmHg within the cluster (Definition 2). The accuracy of point-in-time ONSD measurements for the detection of concurrent ICP >20 mmHg within clusters fulfilling a specific definition of SAIF was compared to the accuracy of ONSD measurements within clusters not fulfilling the particular definition by comparison of independent receiver operating characteristic (ROC) curves. RESULTS: A total of 613 concurrent ONSD-ICP measurements in 109 clusters were made in 73 patients. Twenty-three (21%) clusters fulfilled SAIF Definition 1 and 17 (16%) SAIF Definition 2. For Definition 1, the difference in the area under the curve (AUC) of ROC curves for groups with and without fluctuation was 0.10 (P = 0.0001). There was a fall in the specificity from 98% (95% CI 96 to 99%) to 74% (63 to 83%) and in the positive predictive value from 89% (80 to 95%) to 76% (66 to 84%) with fluctuation. For Definition 2, also, there was a significant difference between the AUC of ROC curves of groups with fluctuation-magnitude >10 mmHg and those with fluctuation-magnitude 5 to 10 mmHg (0.06, P = 0.04) as well as <5 mmHg (0.07, P = 0.01). CONCLUSIONS: Specificity and PPV of ONSD for ICP >20 mmHg are substantially decreased in patients demonstrating acute fluctuation of ICP between high and normal. This may be because of delayed reversal of nerve sheath distension.


Assuntos
Hipertensão Intracraniana/diagnóstico por imagem , Pressão Intracraniana , Nervo Óptico/diagnóstico por imagem , Curva ROC , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Hipertensão Intracraniana/fisiopatologia , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Estudos Retrospectivos , Método Simples-Cego , Ultrassonografia , Adulto Jovem
3.
Neurocrit Care ; 15(3): 506-15, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-21769456

RESUMO

BACKGROUND: Optic nerve ultrasonography (ONUS) may help identify raised intracranial pressure (ICP). The optimal optic nerve sheath diameter (ONSD) cut-off for the identification of intracranial hypertension has not been established, with some clinical studies suggesting a higher cut-off than may be expected on the basis of prior laboratory investigation. OBJECTIVE: To validate ONUS performed by neurointensivists as a technique for the detection of intracranial hypertension and identify the optimal ONSD criterion for the detection of ICP > 20 mmHg. METHODS: Prospective blinded observational study. Patients in the ICU with either external ventricular drains or intraparenchymal ICP monitors at risk for intracranial hypertension were enrolled. The ONSD was measured by neurointensivists at the bedside with simultaneous invasive ICP measurement. An ROC curve was constructed to determine the optimal ONSD for the detection of ICP >  20 mmHg. MEASUREMENTS AND RESULTS: A total of 536 ONSD measurements were performed on 65 patients. Diagnoses included subarachnoid hemorrhage, traumatic brain injury, intracerebral hemorrhage, ischemic stroke and brain tumor. ROC curve analysis revealed area under the curve (AUC) = 0.98 (95% CI 0.96-0.99; P < 0.0001 for AUC = 0.5). Optimal ONSD for detection of ICP > 20 mmHg was ≥0.48 cm sensitivity 96% (95% CI 91-99%); specificity 94% (92-96%). Sensitivity of the higher cutoff of ≥0.52 cm proposed by some authors was only 67% (58-75%), with specificity 98% (97-99%). CONCLUSIONS: Bedside ONSD measurement, performed by neurointensivists, is an accurate, non-invasive method to identify ICP > 20 mmHg in a heterogeneous group of patients with acute brain injury. ONSD ≥0.48 cm has the greatest accuracy, however, internal validation of ONSD criteria may be required.


Assuntos
Ecoencefalografia/instrumentação , Hipertensão Intracraniana/diagnóstico por imagem , Pressão Intracraniana/fisiologia , Nervo Óptico/diagnóstico por imagem , Papiledema/diagnóstico por imagem , Adulto , Idoso , Feminino , Humanos , Unidades de Terapia Intensiva , Hipertensão Intracraniana/etiologia , Hipertensão Intracraniana/terapia , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Papiledema/etiologia , Sistemas Automatizados de Assistência Junto ao Leito , Estudos Prospectivos , Curva ROC , Sensibilidade e Especificidade , Tomografia Computadorizada por Raios X , Transdutores , Ventriculostomia
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