Near-drowning and drowning classification: a proposal to stratify mortality based on the analysis of 1,831 cases.

STUDY OBJECTIVE: To establish an updated classification for near-drowning and drowning (ND/D) according to severity, based on mortality rate of the subgroups. MATERIALS AND METHODS: We reviewed 41,279 cases of predominantly sea water rescues from the coastal area of Rio de Janeiro City, Brazil, from 1972 to 1991. Of this total, 2,304 cases (5.5%) were referred to the Near-Drowning Recuperation Center, and this group was used as the study database. At the accident site, the following clinical parameters were recorded: presence of breathing, arterial pulse, pulmonary auscultation, and arterial BP. Cases lacking records of clinical parameters were not studied. The ND/D were classified in six subgroups: grade 1--normal pulmonary auscultation with coughing; grade 2--abnormal pulmonary auscultation with rales in some pulmonary fields; grade 3--pulmonary auscultation of acute pulmonary edema without arterial hypotension; grade 4--pulmonary auscultation of acute pulmonary edema with arterial hypotension; grade 5--isolated respiratory arrest; and grade 6--cardiopulmonary arrest. RESULTS: From 2,304 cases in the database, 1,831 cases presented all clinical parameters recorded and were selected for classification. From these 1,831 cases, 1,189 (65%) were classified as grade 1 (mortality=0%); 338 (18.4%) as grade 2 (mortality=0.6%); 58 (3.2%) as grade 3 (mortality=5.2%); 36 (2%) as grade 4 (mortality=19.4%); 25 (1.4%) as grade 5 (mortality=44%); and 185 (10%) as grade 6 (mortality=93%) (p<0.000001). CONCLUSION: The study revealed that it is possible to establish six subgroups based on mortality rate by applying clinical criteria obtained from first-aid observations. These subgroups constitute the basis of a new classification.

Common carotid artery: variability of Doppler US velocity measurements.

PURPOSE: To determine if Doppler ultrasound (US) measurements of systolic velocity in the common carotid artery vary markedly with distance from the bifurcation. MATERIALS AND METHODS: Bilateral, insonation angle-corrected velocity was measured with US in the common carotid artery. Measurements were obtained 1, 2, 3, 4, and 5 cm from the carotid artery bifurcation in 20 volunteers (aged 25-43 years) with no history of neurologic or cardiovascular disease. RESULTS: Velocity in the common carotid artery increased with distance (toward the aorta) from the bifurcation (mean increase, 9 cm/sec for each centimeter of distance from the bifurcation, up to the 4-cm distance; P < .001). Velocity increased more rapidly in subjects who were younger (P < .001) and in those with a lower pulse rate (P = .001). CONCLUSION: The distance from the bifurcation at which common carotid artery velocity is measured should be standardized. This may increase the accuracy of the systolic velocity ratio for assessment of internal carotid artery stenosis and decrease some of the reported variability between different centers that perform US of the carotid artery.

Umbilical venous velocity pulsations are related to atrial contraction pressure waveforms in fetal lambs.

OBJECTIVE: To identify the source of umbilical venous velocity pulsations, times of transmission from the atrial contraction pressure waveform to velocity waves in the inferior vena cava, ductus venosus, intra-abdominal umbilical vein, and intra-amniotic umbilical vein were examined. METHODS: Five lamb fetuses at 125-135 days' gestation were instrumented with solid state pressure transducers in the inferior vena cava, fluid-filled catheters in the inferior vena cava and descending aorta, and epicardial pacemakers. Three to 5 days postoperatively, inferior vena cava, ductus venosus, and umbilical vein velocities were examined with Doppler ultrasound. Normal saline was administered and umbilical vein velocity pulsations developed (180 +/- 60 mL). In three fetuses, premature atrial contractions were induced under baseline conditions and after umbilical vein velocity pulsations developed. RESULTS: Times of transmission from the atrial contraction pressure waveform until velocity decreases in the fetal venous system were significantly different in the inferior vena cava, ductus venosus, intra-abdominal umbilical vein, and intra-amniotic umbilical vein (P < .001). Times increased with the distance from the atrium. Inferior vena cava pressure increased with fluid administration from 3.7 +/- 4.7 mmHg to 9.3 +/- 2.3 mmHg (P < .01). Time from increased pressure waveforms with induced premature atrial contractions to the nadir of subsequent umbilical vein velocity waves decreased from 0.123 +/- 0.047 seconds before saline administration to 0.072 +/- 0.039 seconds after saline administration (P < .001). CONCLUSION: Transmission time of atrial pressure into the venous circulation increases with distance from the atrium and decreases with volume loading. Umbilical venous velocity pulsations derive from atrial pressure changes transmitted in a retrograde fashion.

The physiological responses induced by superficial acupuncture: a comparative study of acupuncture stimulation during exhalation phase and continuous stimulation.

This study investigated the physiological effect of superficial acupuncture stimulation during a patient's exhalation phase in a sitting position (SES). The response to SES was compared to the stimulation applied continuously without considering the respiratory phase (CONT). It evaluated a chronic tension-type headache patient's static electromyographic (EMG) activity, pain response, heart rate, pulse height, and skin conductance level. The results indicated that SES stimulation significantly decreased headache intensity and demonstrated a strong trend towards decreasing static EMG activity compared to CONT stimulation. The study concluded that acupuncture, applied on the same point and at the same depth, produced different physiological effects, depending on whether the stimulation was applied during exhalation only or continuously applied. This suggests that the effect of acupuncture derives not only from point selection matching symptoms, but also from a consideration and utilization of the patient's respiratory phase during stimulation.

[Effect of nifedipine on ocular pulse amplitude in normal pressure glaucoma]. / Einfluss des Nifedipins auf die okuläre Pulsamplitude bei Normaldruckglaukom.

BACKGROUND: Ocular pulse amplitude (OPA) is reduced in normal tension glaucoma (NTG) patients when compared to non-glaucomatous, healthy control subjects. This might be related to a vasospastic reaction. The objective of this study was to determine if low OPA in NTG is associated with a vasospastic reaction and its response to vasodilation. METHODS: Nifedipine, a calcium channel blocker, vasodilator and systemic antihypertensive agent improves visual fields in NTG patients following acute and chronic dosing. The effect of 60 mg of daily orally administered nifedipine on OPA, intraocular pressure (IOP, German abbreviation: IOD), blood pressure (BP, German abbreviation: RR) and pulse rate (PR, German abbreviation: HF) were measured prior to and for 3 months after initiating nifedipine therapy in 32 NTG patients with and without a vasospastic reaction as manifested by a local cold exposure test. Before treatment, all patients had reduced OPA evaluated with the Langham Ocular Blood Flow System. RESULTS: During nifedipine treatment NTG patients with a vasospastic reaction showed a significant (p < 0.001) increase in OPA, whereas NTG patients without a vasospastic reaction showed no sig. (p > 0.05) change in OPA. CONCLUSION: There may be two different subgroups of NTG patients, those who have a vasospastic reaction and react to nifedipine, while others lack the ability to react to nifedipine or might have a different, non-vasospastic pathology. Calcium channel blockers and other vasodilators may be useful in the treatment of vasospastic NTG patients.

The nasal response to axillary pressure in non-eosinophilic intrinsic rhinitis.

The exact pathophysiology of intrinsic rhinitis is not fully understood. The generally held belief is that it is due to an imbalance between the outflow of the sympathetic and parasympathetic nervous systems to the nose, perhaps due to excessive parasympathetic or reduced sympathetic activity. In this study the nasal airway response to a predominantly sympathetic stimulus, axillary pressure was studied in 19 patients with intrinsic rhinitis and compared with 16 normal patients. Axillary pressure was applied using a crutch. Following sustained pressure, a significant fall in nasal resistance in the normal group (0.823 kPas/l) and an insignificant fall in the patients with rhinitis (0.0725 kPas/l) was found. Pulse and blood pressure changes were similar in both groups with a significant rise in pulse rate and diastolic blood pressure. The study shows that there is an abnormal response to axillary pressure in intrinsic rhinitis, perhaps due to relative nasal sympathetic hyposensitivity.

Limited microsurgical arteriolysis for complications of digital vasospasm.

Twenty-two digits in seven patients with chronic digital vasospasm were surgically treated after failed medical management. All patients complained of severe ischaemic pain. Chronic digital tip ulceration was present in seven digits and dry gangrene in one. Following surgical microarteriolysis all digital ulcers healed completely. Severe digital ischaemic pain was significantly improved in all digits and completely resolved in 19 of 22 digits.

Increased pulse wave velocity and shortened pulse wave transmission time in hypertension and aging.

We measured pulse wave velocity (PWV) and pulse transmission time (PTT) in 29 patients with hypertension, ranging in age from 37 to 73 years, in a series of 36 normal subjects with the same age range, and in an additional series of 44 normal subjects aged 18-35 years. PWV increases linearly with age for both normal subjects and patients with hypertension, with a corresponding significant decrease in PTT. There was a statistically highly significant (p < 0.001) increase in PWV in hypertension at all ages examined. The present simple noninvasive methods may be useful when evaluating risk factors for atherosclerosis and when evaluating response to therapeutic intervention.

Gaussian pulse decomposition: an intuitive model of electrocardiogram waveforms.

This study presents a novel approach to modeling the electrocardiogram (ECG): the Gaussian pulse decomposition. Constituent waves of the ECG are decomposed into and represented by Gaussian pulses using an iterative algorithm: the chip away decomposition (ChAD) algorithm. At each iteration, a nonlinear minimization method is used to fit a portion of the ECG waveform with a single Gaussian pulse, which is then subtracted from the ECG waveform. The process iterates on the resulting residual waveform until the normalized mean square error is below an acceptable level. Three different minimization methods were compared for their applicability to the ChAD algorithm; the Nelder-Mead simplex method was found to be more noise-tolerant than the Newton-Raphson method or the steepest descent method. Using morphologically different ECG waveforms from the MIT-BIH arrhythmia database, it was demonstrated that the ChAD algorithm is capable of modeling not only normal beats, but also abnormal beats, including those exhibiting a depressed ST segment, bundle branch block, and premature ventricular contraction. An analytical expression for the spectral contributions of the constituent waves was also derived to characterize the ECG waveform in the frequency domain. The Gaussian pulse model, providing an intuitive representation of the ECG constituent waves by use of a small set of meaningful parameters, should be useful for various purposes of ECG signal processing, including signal representation and pattern recognition.

Splenic artery velocity waveforms in small-for-gestational-age fetuses: relationship with pH and blood gases measured in umbilical blood at cordocentesis.

OBJECTIVE: Our purpose was to relate velocity waveforms from the splenic artery with pH and blood gas levels measured at cordocentesis in small-for-gestational-age fetuses and to compare the diagnostic efficiency of splenic artery waveforms with that of other fetal arterial and venous vessels in predicting acid-base status. STUDY DESIGN: Cross-sectional recordings from the splenic artery were obtained by color and pulsed Doppler techniques in 316 appropriately grown fetuses, 12 small-for-gestational-age fetuses with normal umbilical artery velocity waveforms (group 1), and 30 small-for-gestational-age fetuses with abnormal umbilical artery velocity waveforms (group 2). Measurements of splenic artery pulsatility index values in small-for-gestational-age fetuses were compared with those of appropriate-for-gestational-age fetuses. Associations of splenic artery pulsatility index with Po2, Pco2, and pH values measured at cordocentesis were examined and compared with those of umbilical artery, middle cerebral artery, and inferior vena cava. RESULTS: In appropriately grown fetuses pulsatility index values from the splenic artery decrease with advancing gestation (r = 0.51, p < 0.0001). Splenic artery pulsatility index values are lower in group 2 (p < 0.001) but not in group 1 small-for-gestational-age fetuses (p = 0.211). The amplitude of the decrease in the pulsatility index is significantly associated with fetal hypoxemia (r = 0.646, p < 0.001), acidemia (r = 0.593, p < 0.001) and hypercapnia (r = 0.577, p < 0.001). However, logistic regression demonstrates that hypoxia is better predicted by middle cerebral artery pulsatility index, whereas hypercapnia and acidosis are more closely associated with the percent of reverse flow in inferior vena cava. CONCLUSION: A decrease in the splenic artery pulsatility index occurs in small-for-gestational-age fetuses in the presence of abnormal pH and blood gas values, but a more accurate assessment of acid-base status may be obtained with the study of the middle cerebral artery and inferior vena cava.

Do pulse checks cause a significant delay in the initial defibrillation sequence?

This study was undertaken to determine if checking for a pulse between initial defibrillations causes a clinically significant delay in the administration of the defibrillations. Ten emergency department nurses and 10 emergency medicine resident physicians were timed delivering three successive defibrillations (200, 300 and 360 J) to a manikin under three randomly assigned scenarios: (1) without pulse checks; (2) with pulse checks performed by an assistant; and (3) with pulse checks performed by the participant. All participants performed the three defibrillation scenarios using three different models of defibrillators. Repeated measures analysis of variance was used to compare mean defibrillation times for the three scenarios. The mean time was 20.4 +/- 1.0 s for defibrillation without pulse checks; 20.2 +/- 1.2 s with pulse checks by an assistant and 22.0 +/- 2.0 s with pulse checks by the participant. There was a statistically significant difference between no pulse checks and pulse checks by the participant. No statistically significant difference was noted between no pulse checks and pulse checks by an assistant. We conclude that checking for a pulse does cause a statistically significant delay in the administration of defibrillations. This difference, however, is not likely to be clinically relevant.

Cerebral blood flow velocity and pulsation in neonatal respiratory distress syndrome and periventricular hemorrhage.

The present study addressed the hypotheses that cerebral ischemia and/or excessive cerebral blood pulsation contribute to periventricular hemorrhage in preterm newborns with respiratory distress and that the pulse width is a valuable tool to estimate the contribution of cerebral blood pulsation. These hypotheses were tested by following preterm newborns at risk for respiratory distress and periventricular hemorrhage. We monitored for cerebral blood flow velocity (CBFV), cerebral pulse width, and cerebral pulsatility index; for patent ductus arteriosus, capillary Pco2, heart rate (HR) and behavior; and for the occurrence of respiratory distress and periventricular hemorrhage (PVH). The data obtained were analyzed with linear regression with the mode of respiration (spontaneous or supported) and postnatal age as additional covariates. We observed that (a) respiratory distress, either uncomplicated or complicated by PVH, correlates with a low CBFV and a high cerebral pulsatility index; (b) PVH also correlates with a high cerebral pulse width; (c) the increased pulse width precedes the onset of the hemorrhage; and (d) these CBF alterations can be partly attributed to ductal shunting and are ameliorated by mechanical ventilation.

Aneurysm pressure following endovascular exclusion.

OBJECTIVES: To assess the effect of stent-graft implantation on the pressure within an abdominal aortic aneurysm. METHODS: Aneurysm exclusion was performed using an aorto-uniiliac stent-graft in eight patients. Following stent-graft implantation, pressure measurements were performed through a catheter adjacent to the graft in the aneurysm. This "aneurysm pressure" was compared with radial arterial pressure. RESULTS: The pressure was lower in the aneurysm than in the radial artery, in all cases. Mean aneurysm pressure was 36.5/33.8 mmHg, while mean radial arterial pressure was 118.5/50.5 mmHg (p < 0.05, for both systolic and diastolic pressures). These findings corresponded with a reduction in the palpable abdominal pulse, and an absence of perigraft perfusion on follow-up computerised tomography. CONCLUSION: Stent-graft implantation produces a fall in the pressure within an abdominal aortic aneurysm.

[Physical cost of working under conditions of thermal load]. / Koszt fizjologiczny pracy w warunkach obciazenia termicznego.

The objective of this study was to assess the effect of physical load and thermal load on changes in physiological cost of work. A group of 25 students aged 23 +/- 2 years; height 178 +/- 6 cm and weight 72 +/- 11.2 kg, were tested on a bicycle ergometer with physical load of 25, 50, 75, 100 and 150 watts in a climatic chamber at air temperature ta (the mean temperature = 20.5 degrees C) and relative humidity (the mean relative humidity = 68%) and at thermal load WBGT = 27 degrees C. The following parameters were measured: general physical fitness, minute lung ventilation, energy expenditure, relative workload, mechanical efficiency rate, pulse rate and coefficients of correlation between these values. In comparison to values noted under conditions of moderate microclimate, minute lung ventilation, energy expenditure, relative workload and pulse rate were significantly enhanced and coefficient of mechanical lowered at all physical loads under conditions of thermal load WBGT = 27 degrees C. The study revealed significant collaboration between pulse rate at work and increase of minute lung ventilation as well as between energy expenditure at work. There was positive correlation between minute lung ventilation and absolute energy expenditure and %VO2max, and negative correlation between mechanical efficient rate and minute lung ventilation, absolute energy expenditure and %VO2max. The study showed an increased physiological cost of work under conditions of thermal load resulting in declined work efficiency and increased effort necessary to perform individual tasks.

Pulse wave analysis.

PULSE WAVE ANALYSIS IN HISTORICAL TIMES: Interpretation of the arterial pulse has been an important part of the medical examination from ancient times. Graphic methods for clinical pulse wave recording were introduced by Marey in Paris and by Mahomed in London last century. Mahomed showed how such recordings could be used to detect asymptomatic hypertension, and used them to chart the natural history of essential hypertension and to distinguish between this condition and chronic nephritis. Interest in arterial pulse analysis, as applied by Mahomed, lapsed with the introduction of the cuff sphygmomanometer 100 years ago. MODERN PULSE WAVE ANALYSIS: Analysis of the arterial pulse is now regaining favour as limitations of the cuff sphygmomanometer are better recognized (including the ability only to measure extremes of the pulse in the brachial artery). In addition, high-fidelity tonometers have been introduced for very accurate, non-invasive measurement of arterial pulse contour, and there is now a better understanding of arterial hemodynamics, and appreciation of disease and aging effects in humans. It is now possible to record the pulse wave accurately in the radial or carotid artery, to synthesize the ascending aortic pulse waveform, to identify systolic and diastolic periods and to generate indices of ventricular-vascular interaction previously only possible with invasive arterial catheterization. Pressure pulse wave analysis now permits more accurate diagnosis and more logical therapy than was ever possible in the past.

Changes in autonomic function with age: a study of pupillary kinetics in healthy young and old people.

The object of the study was to compare resting pupil diameter in darkness and light, and the pupillary darkness and light reflexes between a group of young and elderly healthy subjects. Twelve young (eight men, four women; median age 19.5 years) and 14 elderly subjects (six men, eight women; median age 69 years) participated. Pupil diameter was monitored with an infra-red television pupillometer. Resting pupil size was measured in light (16 and 32 Cd m-2) and in darkness. The darkness reflex was elicited by switching off the ambient illumination (16 Cd m-2) for 1 s. The light reflex was elicited in darkness by short (200 ms) pulses of green (peak wavelength 565 nm) light at four ascending stimulus intensities (8.5 x 10(-3), 7.0 x 10(-2), 0.43 and 1.84 mW cm-2). The amplitude (mm) and maximum velocity (mm s-1) of the darkness reflex and the latency (ms), amplitude (mm), maximum constriction velocity (mm s-1) and 75% recovery time (s) of the light reflex were measured. The resting pupil diameter was found to be smaller in the elderly group at all three illumination levels (p = 0.001). The amplitude and maximum dilatation velocity of the darkness reflex were smaller for the elderly group (p = 0.001). The amplitude of the light reflex at the three highest light intensities and maximum constriction velocity at all light intensities were smaller in the elderly group (p = 0.002). Seventy-five per cent recovery time was longer in the elderly group (p = 0.02). There was no difference in the latency of the light reflex response between the two groups. The reduced pupil size, diminished darkness reflex amplitude and velocity, and prolonged recovery time of light reflex are consistent with sympathetic deficit in old age. Although the reductions in light reflex amplitude and constriction velocity in the elderly group at first sight would indicate a parasympathetic deficit in old age, they are more likely to be secondary to the grossly diminished pupil size.