Hydrogen sulfide (H 2 S), which has a characteristic rotten egg smell, is a colorless, flammable, water-soluble gas that is primarily considered a toxic agent due to its ability to inhibit mitochondrial respiration through blockade of cytochrome c oxidase. Recent research has demonstrated that H 2 S in low quantities may have the potential to limit cell death ( Lefer, 2007 ). Inhibition of respiration is potentially toxic; however, if depression of respiration occurs in a controlled manner, it may allow non-hibernating species exposed to inhaled H 2 S to enter a state akin to suspended animation (i.e., a slowing of cellular activity to a point where metabolic processes are inhibited but not terminal) and thereby increase tolerance to stress. H 2 S also may cause activation of ATP-dependent K + channels, cause vasodilation properties, and serve as a free radical scavenger. H 2 S has been shown to protect against whole-body hypoxia, lethal hemorrhage, and ischemia-reperfusion i...
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Definitions and Terms ▪ Frequency: The measurement used to categorize several ranges of electrical activity found in the normal and abnormal brain: —Delta: High-amplitude, low-frequency waves seen in sleep —Theta: Low-frequency waves seen in younger children and meditation in adults—may be indicative of pathological activity, such as toxic encephalopathy —Alpha: Higher frequency range seen in relaxation and certain forms of coma —Beta: High frequencies seen during active thinking ▪ Epileptiform discharges: Rhythmic discharges seen focally or diffusely in patients with epilepsy. ▪ Diffuse slowing: Combination of delta and theta frequencies seen in many pathological states—when seen with preserved reactivity to external stimuli (ie, pain, sound); this pattern may have a better prognosis than when responsiveness is absent. ▪ Intermittent rhythmic delta activity: Pathological pattern that can be seen with metabolic, toxic, hypoxic, or other diffuse intracranial disea...
Most clinicians focus on postural symptoms as the hallmark of low CSF pressure. However, postural or exertional factors may be noted in conditions other than that of low CSF pressure . Obstructions to ventricular CSF flow, Arnold-Chiari malformation type 1, subdural hematomas, cerebral venous thrombosis, and sinus disease can all lead to positional and postural headache. Reactive brain edema (causing slit ventricles) may displace brain tissue downward, accounting for Arnold-Chiari type 1 findings.
Echocardiographic Assessment of Severe Left-Sided Valve Lesions Valve lesion Aortic stenosis Aortic regurgitation Mitral stenosis Mitral regurgitation Clinical Symptoms Angina, dyspnea, syncope, heart failure, fatigue, exercise tolerance Dyspnea, fatigue, orthopnea Fatigue, exercise tolerance, dyspnea, cough, wheezing Fatigue, chronic weakness, exhaustion Valve area <1 cm 2 <1 cm 2 Mean gradient >40 mm Hg >10 mm Hg Vena contracta width >0.6 cm >0.7 cm Regurgitant fraction >50% >50% Echocardiographic Assessment of Severe Right-Sided Valve Lesions Tricuspid stenosis Tricuspid regurgitation Pulmonic stenosis Pulmonic regurgitation Valve area <1 cm 2 Vena contracta >0.7 cm CW Doppler peak velocity >4 m/s Color jet fills outflow tract CW Doppler velocity >2.5 m/s CW mean gradient >5 mm Hg Systolic flow reversal in hepatic veins CW Doppler Peak gradient >60 mm Hg Dense CW Doppler with...
1. Preoperative management centers upon: Establishing whether or not a patient has a cardiac rhythm management device (CRMD), by focused history, review of chest radiography (CXR), electrocardiogram (ECG), and physical examination Defining the type of device by reviewing the manufacturer's card, interrogating it with a CRMD programming device, CXR, or querying the manufacturer's databases Determining whether a patient is device dependent for antibradycardia pacing by patient history and device interrogation Determining the device's function through consultation with a cardiologist or CRMD service Next the preoperative preparation should include the following steps: Determine whether electromagnetic interference would be present during the planned procedure. Determine whether reprogramming the device to asynchronous pacing mode or disabling the rate responsiveness function is needed. Suspend the device's antitachyarrhythmia functions, if present....
PACU Discharge Scoring Systems Modified Aldrete Score Postanesthesia Discharge Scoring System Respiration 2: able to take deep breath and cough 1: dyspnea/shallow breathing 0: apnea Vital signs 2: BP + pulse within 20% of baseline 1: BP + pulse within 20–40% of baseline 0: BP + pulse more than 40% off baseline Oxygen saturation 2: maintains SpO 2 >92% on room air 1: needs O 2 inhalation to maintain O 2 saturation >90% 0: O 2 saturation <90% even with supplemental oxygen Activity 2: steady gait, no dizziness or meets preoperative level 1: requires assistance 0: unable to ambulate Consciousness 2: fully awake 1: arousable on calling 0: not responding Nausea and vomiting 2: minimal/treated with PO medication 1: moderate/treated with parenteral medication 0: severe/continues despite treatment Circulation 2: BP ± 20 mm Hg preoperatively 1: BP ± 20–50 mm Hg preoperatively 0: BP ± 50 mm Hg preoperatively Pain Controlled with oral medications and acceptabl...
The higher complication rate of emergency tracheotomy, compared to cricothyrotomy,results from the fact that the trachea is situated deeper in the neck, the posterior tracheal wall lacks the protection of a circumferential cricoid cartilage (increasing the risk of esophageal perforation), there is a greater abundance of adjacent vascular structures, and there is a proximity of the thyroid gland and lung. The palpable, often visible, surface landmarks of the thyroid and cricoid cartilages and the ability to accomplish the task faster, with a minimum of equipment, make emergency cricothyrotomy more attractive than tracheotomy, for the surgeon and nonsurgeon alike. As a consequence, all of the techniques with the exception of percutaneous dilational tracheotomy and possibly needle insufflation in children will involve access to the airway through the cricothyroid membrane (CTM). Ger R, Evans JT. Tracheostomy: an anatomico-clinical review. Clin Anat . 1993;6:337-341. Brantigan C...
Level Dermatome L1 Upper thigh and groin L2 Mid anterior thigh L3 Medial femoral condyle L4 Medial malleolus L5 Dorsum of the foot at metatarsal phalangeal joint S1 Lateral heel S2 Popliteal fossa
Use of Right Heart Catheterization to Diagnose the Etiology of Shock Diagnosis PAOP T SVR Miscellaneous Comments Cardiogenic shock Cardiogenic shock due to myocardial dysfunction Usually extensive infarction (>40% of left ventricle), severe cardiomyopathy, or myocarditis Cardiogenic shock due to mechanical defects Acute ventricular septal defect Oxygen "step-up" at RV level Acute mitral regurgitation Forward T V waves in Paop tracing RV infarction Normal or Elevated RA and RV filling pressures with low or normal Paop Extracardiac obstructive forms of shock Pericardial tamponade Or RA mean, RV end-distolic pulmonary capillary wedge mean pressures are elevated and within 5 mm Hg ...