Workload during cardiopulmonary resuscitation.

OBJECTIVES: Lay resuscitation is crucial for the survival of the patients with out-of-hospital cardiac arrest. Therefore, lay CPR should be a basic skill for everyone. With the growing proportion of retired people in the Western societies, CPR performed by people with preexisting diseases and at risk of cardiac events is expected to grow. There is little knowledge about the workload during CPR and the minimum workload capacity of the rescuer. METHODS: Pulse frequency, oxygen uptake, and CO2 elimination were measured by telemetry, while CPR was performed using a manikin with digital equipment for the standardization of the procedure. The same parameters were measured during a standard exercise testing protocol (spiroergometry) on a bicycle to analyze the aerobic endurance range of the participants. Data from the resuscitation protocols were correlated with those from spiroergometry to establish a simple standard investigation procedure to check people at risk and to give minimum requirements to perform CPR in Watts/kg. The study consisted of two parts: 1 (n = 16) explored minimal workload cutoffs for the rescuer using the 1995 recommendations and 2 (n = 14) tested the latest 2010 guidelines to compare both recommendations. RESULTS: When tested according to the 1995 guidelines, heart frequency of rescuers increased from 83.0 bpm (±11.3) at rest to 109.9 bpm (±12.6; P = 0.0004). The newer 2010 guidelines increased the workload marginally more (n.s.). CONCLUSION: CPR can be performed by healthy people within the range of aerobic endurance. The minimal requirements for trainings are 1.6-1.8 W/kg body weight in standard cycling ergometry. People at risk should be trained very careful. Since there is no significant lower workload when following the 1995 recommendations, people at risk should be trained according to the latest recommendations. In the case of a real resuscitation, such trained individuals must additionally take into account any symptoms.

Alveolar PCO2 oscillations and ventilation at sea level and at high altitude.

This study examines the potential for a ventilatory drive, independent of mean PCO2, but depending instead on changes in PCO2 that occur during the respiratory cycle. This responsiveness is referred to here as "dynamic ventilatory sensitivity." The normal, spontaneous, respiratory oscillations in alveolar PCO2 have been modified with inspiratory pulses approximating alveolar PCO2 concentrations, both at sea level and at high altitude (5,000 m, 16,400 ft.). All tests were conducted with subjects exercising on a cycle ergometer at 60 W. The pulses last about half the inspiratory duration and are timed to arrive in the alveoli during early or late inspiration. Differences in ventilation, which then occur in the face of similar end-tidal PCO2 values, are taken to result from dynamic ventilatory sensitivity. Highly significant ventilatory responses (early pulse response greater than late) occurred in hypoxia and normoxia at sea level and after more than 4 days at 5,000 m. The response at high altitude was eliminated by normalizing PO2 and was reduced or eliminated with acetazolamide. No response was present soon after arrival (<4 days) at base camp, 5,000 m, on either of two high-altitude expeditions (BMEME, 1994, and Kanchenjunga, 1998). The largest responses at 5,000 m were obtained in subjects returning from very high altitude (7,100-8,848 m). The present study confirms and extends previous investigations that suggest that alveolar PCO2 oscillations provide a feedback signal for respiratory control, independent of changes in mean PCO2, suggesting that natural PCO2 oscillations drive breathing in exercise.

In vitro staining of resin composites by liquids ingested by children.

PURPOSE: The purpose of this study was to compare the influence of various children's drinks on the discoloration of dental resin composites. METHODS: Ninety-six disks (3-mm thick, 10 mm in diameter) were prepared from 3 types of composite: (1) submicron; (2) nono; and (3) microhybrid. After polishing and obtaining baseline data, they were equally divided into 4 groups and immersed into 1 of 4 liquids at 37 degrees C: (1) distilled water; (2) Kool-Aid Jammers (grape flavor); (3) Coca-Cola; or (4) snow cone syrup (banana flavor). On days 3, 6, 9, 12, and 15, the samples were measured again for color. On day 18, they were measured for both color and gloss. RESULTS: Overall, the color change during the staining procedure was minimal (deltaE(ab) < 1.67) for all 3 composites, although it appeared that Tetric EvoCeram had the least discoloration. Using 3-way analysis of variance and linear regression analysis, only Estelite sigma in Coco-Cola showed a statistically significant linear relationship between discoloration and stain time. CONCLUSIONS: Three composites reacted differently in various staining solutions. During this study, the 4 solutions did not discolor any of the composites in a way that was clinically significant Tetric EvoCeram may be the most stain resistant material among the 3 tested.

Acute mountain sickness: pulmonary and cerebral oedema of high altitude.

Acute mountain sickness is a condition affecting otherwise healthy individuals on going rapidly to altitude. It is caused by sub-acute hypoxia in susceptible subjects. Its study may provide lessons for the more complicated situation of hypoxia in patients undergoing intensive care. This paper reviews the incidence and aetiology of acute mountain sickness, pulmonary and cerebral oedema of high altitude and possible mechanisms are discussed. Prophylaxis depends on an awareness of the condition in all those venturing to high altitude and guidelines are suggested. The treatment of the established condition is reviewed.

Serum erythropoietin in humans at high altitude and its relation to plasma renin.

Serum immunoreactive erythropoietin (siEp) was estimated in samples collected from members of two scientific and mountaineering expeditions, to Mount Kongur in Western China and to Mount Everest in Nepal. SiEp was increased above sea-level control values 1 and 2 days after arrival at 3,500 m and remained high on ascent to 4,500 m. Thereafter, while subjects remained at or above 4,500 m, siEp declined, and by 22 days after the ascent to 4,500 m was at control values but increased on ascent to higher altitude. Thus siEp was at a normal level during the maintenance of secondary polycythemia from high-altitude exposure. On descent, with removal of altitude hypoxia, siEp decreased, but despite secondary polycythemia levels remained measurable and in the range found in subjects normally resident at sea level. On Mount Everest, siEp was significantly (P less than 0.01) elevated above preexpedition sea-level controls after 2-4 wk at or above 6,300 m. There was no correlation between estimates of siEp and plasma renin activity in samples collected before and during both expeditions.

Nocturnal periodic breathing at altitudes of 6,300 and 8,050 m.

Nocturnal periodic breathing was studied in eight well-acclimatized subjects living at an altitude of 6,300 m [barometric pressure (PB) 350-352 Torr] for 3-5 wk and in four subjects during one night at 8,050 m altitude (PB 281-285 Torr). The measurements at 6,300 m included tidal volume by inductance plethysmography, arterial O2 saturation by ear oximetry (calibrated by arterial blood samples), electrocardiogram (ECG), and electrooculogram. At 8,050 m, periodic breathing was inferred from the cyclical variation in heart rate obtained from a night-long ECG record. All subjects at 6,300 m altitude showed well-marked periodic breathing with apneic periods. Cycle length averaged 20.5 s with 7.9 s apnea. Minimal arterial O2 saturation averaged 63.4% corresponding to a PO2 of approximately 33 Torr, i.e., approximately 6 Torr lower than the normal value at rest during daytime. This was probably the most severe hypoxemia of the 24-h period. At 8,050 m altitude, the cycle length averaged 15.4 s, much longer than predicted by a theoretical model. Cyclical variations in heart rate caused by periodic breathing occurred in all subjects, but abnormal cardiac rhythms such as ventricular premature contractions were uncommon. The severe arterial hypoxemia caused by periodic breathing may be an important determinant of tolerance to these great altitudes.

Severe gingival recession in trisomy 18 primary dentition. A clinicopathologic case report of self-inflicted injury associated with mental retardation.

This clinicopathologic case report documents severe gingival recession in the primary dentition of a trisomy 18 patient. Primary molar and canine teeth exhibited recession extending beyond the midpoint of the buccal aspect of the root, occasionally reaching the root apex. Radiographic examination revealed taurodontism in both primary and permanent teeth. Clinical and histopathologic findings, along with case history, eliminated the possibility of prepubertal periodontitis and suggested a diagnosis of self-inflicted injury associated with mental retardation. Histologic examination of the primary teeth revealed normal cementum and dentin structure. Taurodontism, histologic structure of the dentition, and severe attachment loss in the primary dentition have not been described previously in trisomy 18.

Serial changes in spirometry during an ascent to 5,300 m in the Nepalese Himalayas.

The aims of the present study were to determine the changes in forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV1) and peak expiratory flow (PEF), during an ascent to 5,300 m in the Nepalese Himalayas, and to correlate the changes with arterial oxygen saturation measured by pulse oximetry (SpO2) and symptoms of acute mountain sickness (AMS). Forty-six subjects were studied twice daily during an ascent from 2,800 m (mean barometric pressure 550.6 mmHg) to 5,300 m (mean barometric pressure 404.3 mmHg) during a period of between 10 and 16 days. Measurements of FVC, FEV1, PEF, SpO2, and AMS were recorded. AMS was assessed using a standardized scoring system. FVC fell with altitude, by a mean of 4% from sea level values [95% confidence intervals (CI) 0.9% to 7.4%] at 2,800 m, and 8.6% (95% CI 5.8 to 11.4%) at 5,300 m. FEV1 did not change with increasing altitude. PEF increased with altitude by a mean of 8.9% (95% CI 2.7 to 15.1%) at 2,800 m, and 16% (95% CI 9 to 23%) at 5,300 m. These changes were not significantly related to SpO2 or AMS scores. These results confirm a progressive fall in FVC and increase in PEF with increasing hypobaric hypoxia while FEV1 remains unchanged. The increase in PEF is less than would be predicted from the change in gas density. The fall in FVC may be due to reduced inspiratory force producing a reduction in total lung capacity; subclinical pulmonary edema; an increase in pulmonary blood volume, or changes in airway closure. The absence of a correlation between the spirometric changes and SpO2 or AMS may simply reflect that these measurements of pulmonary function are not sufficiently sensitive indicators of altitude-related disease. Further studies are required to clarify the effects of hypobaric hypoxia on lung volumes and flows in an attempt to obtain a unifying explanation for these changes.

Elevated plasma cholecystokinin at high altitude: metabolic implications for the anorexia of acute mountain sickness.

The aims of the present study were to measure the satiety neuropeptide cholecystokinin (CCK) in humans at terrestrial high altitude to investigate its possible role in the pathophysiology of anorexia, cachexia, and acute mountain sickness (AMS). Nineteen male mountaineers aged 38 +/- 12 years participated in a 20 +/- 5 day trek to Mt. Kanchenjunga basecamp (BC) located at 5,100 m, where they remained for 7 +/- 5 days. Subjects were examined at rest and during a maximal exercise test at sea-level before/after the expedition (SL1/SL2) and during the BC sojourn. There was a mild increase in Lake Louise AMS score from 1.1 +/- 1.2 points at SL1 to 2.3 +/- 2.3 points by the end of the first day at BC (P < 0.05). A marked increase in resting plasma CCK was observed on the morning of the second day at BC relative to sea-level control values (62.9 +/- 42.2 pmol/L(-1) vs. SL1: 4.3 +/- 8.3 pmol/L(-1), P < 0.05 vs. SL2: 26.5 +/- 25.2 pmol/L(-1), P < 0.05). Maximal exercise increased CCK by 78.5 +/- 24.8 pmol/L(-1), (P < 0.05 vs. resting value) during the SL1 test and increased the plasma concentration of non-esterified fatty acids and glycerol at BC (P < 0.05 vs. SL1/SL2). The CCK response was not different in five subjects who presented with anorexia on Day 2 compared with those with a normal appetite. While there was no relationship between the increase in CCK and AMS score at BC, a more pronounced increase in resting CCK was observed in subjects with AMS (> or =3 points at the end of Day 1 at BC) compared with those without (+98.9 +/- 1.4 pmol/L(-1) vs. +67.6 +/- 37.2 pmol/L(-1), P < 0.05). Caloric intake remained remarkably low during the stay at BC (8.9 +/- 1.4 MJ.d(-1)) despite a progressive decrease in total body mass (-4.5 +/- 2.1 kg after 31 +/- 13 h at BC, P < 0.05 vs. SL1/SL2), which appeared to be due to a selective loss of torso adipose tissue. These findings suggest that the satiogenic effects of CCK may have contributed to the observed caloric deficit and subsequent cachexia at high altitude despite adequate availability of palatable foods. The metabolic implications of elevated CCK in AMS remain to be elucidated.

High altitude headache: treatment with ibuprofen.

Up to half of those who ascend rapidly to altitudes of over 3,000 m may experience symptoms of acute mountain sickness (AMS) and of these some 95% may suffer from high altitude headache. We report the first controlled trial specifically to assess an oral drug therapy for this common symptom. Subjects were 21 members of mountaineering expeditions to similar altitudes in the Bolivian Andes and the Himalayas in Nepal. The study was of a randomized, placebo-controlled, double-blind, within-patient crossover design. Ibuprofen was significantly superior to placebo both in reducing headache severity and in speed of relief (a mean difference of 94 min in time to no/minimal headache). Only 14% of subjects who initially took ibuprofen felt the need for further medication compared to 83% of those who took placebo first (p = 0.02). Of the 11 subjects completing both phases of the crossover, 8 (73%) favored ibuprofen while the remainder had no preference (p = 0.004). No attributable adverse effects occurred. The results suggest that ibuprofen is a safe and effective treatment for high altitude headache.

Severe spontaneous intracranial hypotension and Marfan syndrome in an adolescent.

We describe a 14-year-old girl with Marfan syndrome who presented with severe postural headache. Dural ectasia was demonstrated radiologically. Cerebrospinal fluid (CSF) pressure was immeasurable on formal measurement. Radionucleide cisternography failed to demonstrate a CSF leak. We consider that the underlying fibrillinopathy in Marfan syndrome rendered the dura sufficiently permeable to CSF leakage to cause the low CSF pressure headache. The patient was treated successfully with epidural autologous blood patch.

Aetiology of neonatal sepsis in Blantyre, Malawi: 1996-2001.

AIM: The aim of this retrospective study was to report causes, antibiotic resistance and outcome of neonatal sepsis (often fatal in developing countries) in Malawi. METHODS: All blood and cerebrospinal fluid isolates collected between January 1996 and December 2001 from inpatients aged 0-30 days with suspected sepsis at Queen Elizabeth Central Hospital, Blantyre, Malawi were reviewed. In vitro resistance to antibiotics commonly used in Malawi was assessed. Case fatality rate was analysed with respect to age, bacterial pathogen and infection site. RESULTS: A total of 801 bacteria were isolated from 784 neonates over 6 years-599 isolates from blood and 202 from cerebrospinal fluid. Overall, 54% of bacteria were gram-positive and 46% gram-negative. The commonest causes of neonatal sepsis were group B Streptococcus (17%) and non-typhoidal Salmonella (14%). In vitro antibiotic susceptibility to the first-line antibiotic combination of penicillin and gentamicin was 78% for all isolates, but in vitro sensitivities to gentamicin for Klebsiella spp and non-typhoidal Salmonella were only 33% and 53%, respectively. In-hospital case fatality rate was known for only 301 cases and was high at 48%. Group B Streptococcus was associated with the best outcome. Mortality was significantly higher if presentation was in the 1st week of life or if sepsis was caused by gram-negative bacteria. The causes of neonatal sepsis in this population show a different pattern from other studies in developing countries.

The ventilatory response to hypoxia: how much is good for a mountaineer?

Methods for measuring the ventilatory response to hypoxia (HVR) are reviewed. The criteria for success as a high altitude mountaineer are defined as freedom from acute mountain sickness (AMS) and ability to perform well at extreme altitude. The evidence for a brisk HVR being protective against AMS and associated with successful high altitude performance is reviewed. The contrary evidence of blunted HVR in high altitude residence and some elite climbers is discussed. The effect of a brisk HVR in producing periodic breathing when asleep at altitude is noted. It seems that there is an optimum HVR for different circumstances and peoples. A brisk HVR is a benefit in lowlanders going to altitude for the first time whereas a blunted HVR is appropriate for high altitude residents and possibly for very experienced elite climbers.

Salt and water control at altitude.

The physiological effect of altitude hypoxia, in the absence of exercise, is a sodium and water diuresis with decrease in plasma and extra-cellular volumes. Plasma aldosterone concentrations (PAC) are reduced but plasma atrial natriuretic peptide (ANP) levels are modestly increased. Day-long exercise at low altitude has almost opposite effects on fluid balance. There is an anti-diuresis, sodium retention, expansion of the plasma and extra-cellular compartments, elevation of PAC and ANP. Subjects who develop acute mountain sickness (AMS) show a pathological response to hypoxia even before the development of symptoms. There is an anti-diuresis, sodium retention, increased plasma and extra-cellular volumes and increased PAC compared with subjects resistant to AMS. Plasma ANP tends to be elevated compared with sea level values but the relation of ANP levels to AMS is variable. In general therefore, the pathological response to altitude hypoxia parallels that of exercise at low altitude and is opposite to the physiological response. Both exercise and the pathological response predispose the subject to edema and are probably important in the genesis of AMS.