The ratification status of ILO conventions related to occupational safety and health and its relationship with reported occupational fatality rates

The aim of this study was to assess the relationship between the ratification status of occupational safety and health (OSH)-related ILO conventions and reported occupational fatality rates of ILO member countries, while controlling for possible confounding factors. ILO member states were divided into 4 levels of income status, based on the gross national income per capita. Seventeen conventions designated as OSH-related were examined. Reported country occupational fatality rates were compared according to the ratification status of these 17 conventions and multiple regression analyses were conducted to assess the relationship between the fatality rates, ratification status, income level and length of ILO membership. Fatality rates were inversely and significantly related to income levels. In general, non-ratifying countries had higher work-related fatality rates than ratifying countries. A statistical model for identifying predictors of fatal injury rates showed that a larger number of conventions ratified was significantly associated with lower fatality rates. The fact that non-ratifying countries generally have higher fatality rates than ratifying ones supports the notion that all countries should promote ratification of ILO conventions aimed at improving OSH conditions.

Global estimates of fatal work-related diseases

BACKGROUND

Work-related mortality is a relatively new concept which aims to widen occupational health and safety; to take into account not only recognized fatal occupational accidents and diseases but also other work-related deaths. Few countries in the world have a register for work-related diseases.

METHODS

Estimates are calculated using baseline world mortality scenarios of all diseases for the year 2000 and attributable fractions made for work-related diseases in Finland, as adjusted.

RESULTS

It is estimated that about 2 million work-related deaths take place annually. Men suffer two thirds of those deaths. The biggest groups of work-related diseases are cancers, circulatory diseases and communicable diseases.

CONCLUSIONS

Information about work-related diseases is needed for prevention, as people in developed countries are working longer, and the age of retirement is being raised in many countries. As a result, workers are being exposed to different kinds of substances and working conditions for a longer time. In developing countries, work exposures may already start in infancy. Due to industrialization, workers in developing countries are facing new conditions with a lack of relevant knowledge and skills. With the help of information, nations can direct resources and skills for appropriate purposes such as regulatory measures on health and safety at work.

The pulmonary artery catheter: the tool versus treatments based on the tool

The pulmonary artery catheter (PAC) is a powerful tool that has been used extensively in the assessment and monitoring of cardiovascular physiology. Gross misinterpretation of data gathered by the PAC is common, and its routine use without any specific interventions has not been shown to influence outcome. However, there currently is no evidence from randomized, controlled trials that any diagnostic or monitoring tool used in intensive care patients improves outcome. Studies evaluating the use of the PAC have included numerous potential confounding factors, and should be interpreted with caution. The information obtained with the PAC should be used to find better treatment strategies, and these strategies, instead of the tool itself, should be tested in clinical trials.

Effects of prolonged endotoxemia on liver, skeletal muscle and kidney mitochondrial function

Introduction

Sepsis may impair mitochondrial utilization of oxygen. Since hepatic dysfunction is a hallmark of sepsis, we hypothesized that the liver is more susceptible to mitochondrial dysfunction than the peripheral tissues, such as the skeletal muscle. We studied the effect of prolonged endotoxin infusion on liver, muscle and kidney mitochondrial respiration and on hepatosplanchnic oxygen transport and microcirculation in pigs.

Methods

Twenty anesthetized pigs were randomized to receive either endotoxin or saline infusion for 24 hours. Muscle, liver and kidney mitochondrial respiration was assessed. The cardiac output (thermodilution) and the carotid, superior mesenteric and kidney arterial, portal venous (ultrasound Doppler) and microcirculatory blood flow (laser Doppler) were measured, and systemic and regional oxygen transport and lactate exchange were calculated.

Results

Endotoxin infusion induced hyperdynamic shock and impaired the glutamate-dependent and succinate-dependent mitochondrial respiratory control ratio in the liver (glutamate, median (range) endotoxemia 2.8 (2.3–3.8) vs controls 5.3 (3.8–7.0); P < 0.001; succinate, endotoxemia 2.9 (1.9–4.3) vs controls 3.9 (2.6–6.3), P = 0.003). While the ADP added/oxygen consumed ratio was reduced with both substrates, the maximal ATP production was impaired only in the succinate-dependent respiration. Hepatic oxygen consumption and extraction, and the liver surface laser Doppler blood flow remained unchanged. Glutamate-dependent respiration in the muscle and kidney was unaffected.

Conclusion

Endotoxemia reduces the efficiency of hepatic mitochondrial respiration but neither skeletal muscle nor kidney mitochondrial respiration, independent of regional and microcirculatory blood flow changes.

The Effects of Dexmedetomidine/Remifentanil and Midazolam/Remifentanil on Auditory-Evoked Potentials and Electroencephalogram at Light-to-Moderate Sedation Levels in Healthy Subjects

Avoidance of excessively deep sedation levels is problematic in intensive care patients. Electrophysiologic monitoring may offer an approach to solving this problem. Since electroencephalogram (EEG) responses to different sedation regimens vary, we assessed electrophysiologic responses to two sedative drug regimens in 10 healthy volunteers. Dexmedetomidine/remifentanil (dex/remi group) and midazolam/remifentanil (mida/remi group) were infused 7 days apart. Each combination of medications was given at stepwise intervals to reach Ramsay scores (RS) 2, 3, and 4. Resting EEG, bispectral index (BIS), and the N100 amplitudes of long-latency auditory-evoked potentials (ERP) were recorded at each level of sedation. During dex/remi, resting EEG was characterized by a recurrent high-power low-frequency pattern which became more pronounced at deeper levels of sedation. BIS Index decreased uniformly in only the dex/remi group (from 94 +/- 3 at baseline to 58 +/- 14 at RS 4) compared to the mida/remi group (from 94 +/- 2 to 76 +/- 10; P = 0.029 between groups). The ERP amplitudes decreased from 5.3 +/- 1.3 at baseline to 0.4 +/- 1.1 at RS 4 (P = 0.003) in only the mida/remi group. We conclude that ERPs in volunteers sedated with dex/remi, in contrast to mida/remi, indicate a cortical response to acoustic stimuli, even when sedation reaches deeper levels. Consequently, ERP can monitor sedation with midazolam but not with dexmedetomidine. The reverse is true for BIS.

Membrane microdialysis: Evaluation of a new method to assess splanchnic tissue metabolism

OBJECTIVE

Measuring peritoneal lactate concentrations could be useful for detecting splanchnic hypoperfusion. The aims of this study were to evaluate the properties of a new membrane-based microdialyzer in vitro and to assess the ability of the dialyzer to detect a clinically relevant decrease in splanchnic blood flow in vivo.

DESIGN

A membrane-based microdialyzer was first validated in vitro. The same device was tested afterward in a randomized, controlled animal experiment.

SETTING

University experimental research laboratory.

SUBJECTS

Twenty-four Landrace pigs of both genders.

INTERVENTIONS

In vitro: Membrane microdialyzers were kept in warmed sodium lactate baths with lactate concentrations between 2 and 8 mmol/L for 10-120 mins, and microdialysis lactate concentrations were measured repeatedly (210 measurements). In vivo: An extracorporeal shunt with blood reservoir and roller pump was inserted between the proximal and distal abdominal aorta, and a microdialyzer was inserted intraperitoneally. In 12 animals, total splanchnic blood flow (measured by transit time ultrasound) was reduced by a median 43% (range, 13% to 72%) by activating the shunt; 12 animals served as controls.

MEASUREMENTS AND MAIN RESULTS

In vitro: The fractional lactate recovery was 0.59 (0.32-0.83) after 60 mins and 0.82 (0.71-0.87) after 90 mins, with no further increase thereafter. At 60 and 90 mins, the fractional recovery was independent of the lactate concentration. In vivo: Abdominal blood flow reduction resulted in an increase in peritoneal microdialysis lactate concentration from 1.7 (0.3-3.8) mmol/L to 2.8 (1.3-6.2) mmol/L (p = .006). At the same time, mesenteric venous-arterial lactate gradient increased from 0.1 (-0.2-0.8) mmol/L to 0.3 (-0.3 -1.8) mmol/L (p = .032), and mesenteric venous-arterial Pco2 gradients increased from 12 (8-19) torr to 21 (11-54) torr (p = .005).

CONCLUSIONS

Peritoneal membrane microdialysis provides a method for the assessment of splanchnic ischemia, with potential for clinical application.

Decreasing gut wall glucose as an early marker of impaired intestinal perfusion

OBJECTIVE

The aim of this study was to assess the microcirculatory and metabolic consequences of reduced mesenteric blood flow.

DESIGN

Prospective, controlled animal study.

SETTING

The surgical research unit of a university hospital.

SUBJECTS

A total of 13 anesthetized and mechanically ventilated pigs.

INTERVENTIONS

Pigs were subjected to stepwise mesenteric blood flow reduction (15% in each step, n = 8) or served as controls (n = 5). Superior mesenteric arterial blood flow was measured with ultrasonic transit time flowmetry, and mucosal and muscularis microcirculatory perfusion in the small bowel were each measured with three laser Doppler flow probes. Small-bowel intramucosal Pco2 was measured by tonometry, and glucose, lactate (L), and pyruvate (P) were measured by microdialysis.

MEASUREMENTS AND MAIN RESULTS

In control animals, superior mesenteric arterial blood flow, mucosal microcirculatory blood flow, intramucosal Pco2, and the lactate/pyruvate ratio remained unchanged. In both groups, mucosal blood flow was better preserved than muscularis blood flow. During stepwise mesenteric blood flow reduction, heterogeneous microcirculatory blood flow remained a prominent feature (coefficient of variation, approximately 45%). A 30% flow reduction from baseline was associated with a decrease in microdialysis glucose concentration from 2.37 (2.10-2.70) mmol/L to 0.57 (0.22-1.60) mmol/L (p < .05). After 75% flow reduction, the microdialysis lactate/pyruvate ratio increased from 8.6 (8.0-14.1) to 27.6 (15.5-37.4, p < .05), and arterial-intramucosal Pco2 gradients increased from 1.3 (0.4-3.5) kPa to 10.8 (8.0-16.0) kPa (p < .05).

CONCLUSIONS

Blood flow redistribution and heterogeneous microcirculatory perfusion can explain apparently maintained regional oxidative metabolism during mesenteric hypoperfusion, despite local signs of anaerobic metabolism. Early decreasing glucose concentrations suggest that substrate supply may become crucial before oxygen consumption decreases.

Practical sources of error in measuring pulmonary artery occlusion pressure: a study in participants of a special intensivist training program of The Scandinavian Society of Anaesthesiology and Intensive Care Medicine (SSAI)

BACKGROUND

Physiological data obtained with the pulmonary artery catheter (PAC) are susceptible to errors in measurement and interpretation. Little attention has been paid to the relevance of errors in hemodynamic measurements performed in the intensive care unit (ICU). The aim of this study was to assess the errors related to the technical aspects (zeroing and reference level) and actual measurement (curve interpretation) of the pulmonary artery occlusion pressure (PAOP).

METHODS

Forty-seven participants in a special ICU training program and 22 ICU nurses were tested without pre-announcement. All participants had previously been exposed to the clinical use of the method. The first task was to set up a pressure measurement system for PAC (zeroing and reference level) and the second to measure the PAOP.

RESULTS

The median difference from the reference mid-axillary zero level was - 3 cm (-8 to + 9 cm) for physicians and -1 cm (-5 to + 1 cm) for nurses. The median difference from the reference PAOP was 0 mmHg (-3 to 5 mmHg) for physicians and 1 mmHg (-1 to 15 mmHg) for nurses. When PAOP values were adjusted for the differences from the reference transducer level, the median differences from the reference PAOP values were 2 mmHg (-6 to 9 mmHg) for physicians and 2 mmHg (-6 to 16 mmHg) for nurses.

CONCLUSIONS

Measurement of the PAOP is susceptible to substantial error as a result of practical mistakes. Comparison of results between ICUs or practitioners is therefore not possible.

A randomized, blinded, multicenter trial of lipid-associated amphotericin B alone versus in combination with an antibody-based inhibitor of heat shock protein 90 in patients with invasive candidiasis

BACKGROUND

Mycograb (NeuTec Pharma) is a human recombinant monoclonal antibody against heat shock protein 90 that, in laboratory studies, was revealed to have synergy with amphotericin B against a broad spectrum of Candida species.

METHODS

A double-blind, randomized study was conducted to determine whether lipid-associated amphotericin B plus Mycograb was superior to amphotericin B plus placebo in patients with culture-confirmed invasive candidiasis. Patients received a lipid-associated formulation of amphotericin B plus a 5-day course of Mycograb or placebo, having been stratified on the basis of Candida species (Candida albicans vs. non-albicans species of Candida). Inclusion criteria included clinical evidence of active infection at trial entry plus growth of Candida species on culture of a specimen from a clinically significant site within 3 days after initiation of study treatment. The primary efficacy variable was overall response to treatment (clinical and mycological resolution) by day 10.

RESULTS

Of the 139 patients enrolled from Europe and the United States, 117 were included in the modified intention-to-treat population. A complete overall response by day 10 was obtained for 29 (48%) of 61 patients in the amphotericin B group, compared with 47 (84%) of 56 patients in the Mycograb combination therapy group (odds ratio [OR], 5.8; 95% confidence interval [CI], 2.41-13.79; P<.001). The following efficacy criteria were also met: clinical response (52% vs. 86%; OR, 5.4; 95% CI, 2.21-13.39; P<.001), mycological response (54% vs. 89%; OR, 7.1; 95% CI, 2.64-18.94; P<.001), Candida-attributable mortality (18% vs. 4%; OR, 0.2; 95% CI, 0.04-0.80; P = .025), and rate of culture-confirmed clearance of the infection (hazard ratio, 2.3; 95% CI, 1.4-3.8; P = .001). Mycograb was well tolerated.

CONCLUSIONS

Mycograb plus lipid-associated amphotericin B produced significant clinical and culture-confirmed improvement in outcome for patients with invasive candidiasis.

The contribution of occupational risks to the global burden of disease: summary and next steps

BACKGROUND

The Comparative Risk Assessment (CRA) project of the World Health Organization (WHO) assessed worldwide mortality and morbidity in the year 2000 resulting from exposures to selected occupational hazards. This article summarizes findings of the WHO CRA project, presents the estimates of the International Labor Organization (ILO) for total deaths due to workplace risks, and calls for action.

OBJECTIVES

Global burden estimates and counts of deaths assist ministers and other decision and policy makers to make informed decisions and to take action regarding risk reduction.

METHODS

The WHO CRA methodology combined the proportions of the population exposed to five occupational hazards (excluding numerous risks due to inadequate global data) with relative risk measures to estimate attributable fractions of the selected health outcomes for both morbidity and mortality. ILO estimates of total numbers of global work-related injury deaths apply national fatality rates to employment data for the particular country; for disease deaths ILO uses an attributable risk approach.

RESULTS

In 2000, the selected occupational risk factors were responsible worldwide for 37% of back pain, 16% of hearing loss, 13% of chronic obstructive pulmonary disease (COPD), 11% of asthma, 8% of injuries, 9% of lung cancer and 2% of leukemia, and about 100% of pneumoconioses and mesothelioma. These selected risks at work resulted in the loss of about 24 million years of healthy life and caused 850,000 deaths worldwide, about 40% of the ILO estimate of 2.2 million total deaths.

CONCLUSIONS

These global and regional analyses have identified areas where specific preventive actions are required.

Tracheal tear and tension pneumothorax complicating bronchoscopy-guided percutaneous tracheostomy

Percutaneous dilatational tracheostomy (PDT) is a frequently conducted procedure in critically ill patients. Bronchoscopic guidance of PDT is generally recommended to minimize the risk of unintentional tracheal injury. We present a case of tracheal tear and tension pneumothorax, a rare but potentially life-threatening complication, during continuously bronchoscopy-guided PDT. Sealing the large tracheal air fistula with the cuff of an endotracheal tube helped bridge time to definitive surgical repair in our patient. Bronchoscopic guidance may minimize, but cannot completely eliminate, the risk of tracheal injury during PDT.

Changes in respiratory mechanics and gas exchange during the acute respiratory distress syndrome

BACKGROUND

The time course of impairment of respiratory mechanics and gas exchange in the acute respiratory distress syndrome (ARDS) remains poorly defined. We assessed the changes in respiratory mechanics and gas exchange during ARDS. We hypothesized that due to the changes in respiratory mechanics over time, ventilatory strategies based on rigid volume or pressure limits might fail to prevent overdistension throughout the disease process.

METHODS

Seventeen severe ARDS patients {PaO2/FiO2 10.1 (9.2-14.3) kPa; 76 (69-107) mmHg [median (25th-75th percentiles)] and bilateral infiltrates} were studied during the acute, intermediate, and late stages of ARDS (at 1-3, 4-6 and 7 days after diagnosis). Severity of lung injury, gas exchange, and hemodynamics were assessed. Pressure-volume (PV) curves of the respiratory system were obtained, and upper and lower inflection points (UIP, LIP) and recruitment were estimated.

RESULTS

(1) UIP decreased from early to established (intermediate and late) ARDS [30 (28-30) cmH2O, 27 (25-30) cmH2O and 25 (23-28) cmH2O (P=0.014)]; (2) oxygenation improved in survivors and in patients with non-pulmonary etiology in late ARDS, whereas all patients developed hypercapnia from early to established ARDS; and (3) dead-space ventilation and pulmonary shunt were larger in patients with pulmonary etiology during late ARDS.

CONCLUSION

We found a decrease in UIP from acute to established ARDS. If applied to our data, the inspiratory pressure limit advocated by the ARDSnet (30 cmH2O) would produce ventilation over the UIP, with a consequent increased risk of overdistension in 12%, 43% and 65% of our patients during the acute, intermediate and late phases of ARDS, respectively. Lung protective strategies based on fixed tidal volume or pressure limits may thus not fully avoid the risk of lung overdistension throughout ARDS.

Pulmonary capillary pressure. A review

Pulmonary capillary pressure (Pcap) is the predominant force that drives fluid out of the pulmonary capillaries into the interstitium. Increasing hydrostatic capillary pressure is directly proportional to the lung's transvascular filtration rate, and in the extreme leads to pulmonary edema. In the pulmonary circulation, blood flow arises from the transpulmonary pressure gradient, defined as the difference between pulmonary artery (diastolic) pressure and left atrial pressure. The resistance across the pulmonary vasculature consists of arterial and venous components, which interact with the capacitance of the compliant pulmonary capillaries. In pathological states such as acute respiratory distress syndrome, sepsis, and high altitude or neurogenic lung edema, the longitudinal distribution of the precapillary arterial and the postcapillary venous resistance varies. Subsequently, the relationship between Pcap and pulmonary artery occlusion pressure (PAOP) is greatly variable and Pcap can no longer be predicted from PAOP. In clinical practice, PAOP is commonly used to guide fluid therapy, and Pcap as a hemodynamic target is rarely assessed. This approach is potentially misleading. In the presence of a normal PAOP and an increased pressure gradient between Pcap and PAOP, the tendency for fluid leakage in the capillaries and subsequent edema development may substantially be underestimated. Tho-roughly validated methods have been developed to assess Pcap in humans. At the bedside, measurement of Pcap can easily be determined by analyzing a pressure transient after an acute pulmonary artery occlusion with the balloon of a Swan-Ganz catheter.

Moving knowledge of global burden into preventive action

BACKGROUND

Estimation of the global burden of disease and injury due to selected occupational factors is a topic of interest to policy makers, governments, and international bodies. The World Health Organization (WHO) has implemented a Comparative Risk Assessment (CRA) to estimate risk to exposed populations.

METHODS

Estimates of the risk factor-burden relationships by age, sex, and WHO subregion were generated. Risk measurements (relative risks and mortality rates) for the health outcomes were determined primarily from studies published in peer review journals. The resulting burden was described as the attributable fraction of disease or injury, using both mortality and disability-adjusted life years (DALYs).

RESULTS

The papers in this issue include discussions of worldwide mortality and morbidity from lung cancer, leukemia, and malignant mesothelioma arising from occupational exposures; mortality and morbidity from asthma, COPD, and pneumoconiosis; the global burden of low back pain; exposure to contaminated sharps injuries among health care workers; noise-induced hearing loss; and occupational injuries. Three papers focus on economic issues: estimation of net-costs for prevention of occupational low back pain; cost effectiveness of occupational health interventions; and the cost effectiveness of interventions in the prevention of silicosis.

CONCLUSIONS

The magnitude of the occupational health burden in the world is overwhelming, and the causes and mechanisms are multiple and complex. Commitment from all stakeholders is imperative to translate economic progress into sustainable human development and well-being.

Review of estimates of the global burden of injury and illness due to occupational exposures

BACKGROUND

Over the last decade, there have been several attempts to estimate the global burden of ill health due to work activity. The most recent of these is the Comparative Risk Assessment (CRA) project of the World Health Organization.

METHODS

Published estimates of global burden of injury and disease due to occupational factors were summarized, compared, and contrasted with the aim of putting the CRA estimates into context, identifying the most reliable and appropriate estimate for total burden due to occupational risks, and making recommendations regarding future work.

RESULTS

The best estimate of global work-related deaths of workers is approximately two million per year, with disease responsible for the vast majority of these, but even this is likely to be a considerable underestimate of the true number of deaths because of shortcomings in the available data.

CONCLUSIONS

The CRA estimates of burden due to individual risk factors appear appropriate for the limited number of exposures and conditions included, but are a major underestimate of the overall number of work-related deaths at a global level due to exclusion of risk factors because of data limitations. Improvements in global estimates are likely to come from the use of different methodologies and improvements in the availability and use of local data.

Highs and lows in high-risk surgery: the controversy of goal-directed haemodynamic management

Although various systems have been developed to identify patients at increased risk of peri- and postoperative mortality and morbidity, little effort has been made in developing tools to reduce this risk. In this issue of Critical Care, Pearse et al. publish two reports related to predicting and improving outcome in high-risk surgical patients. Rather than conducting large, multicentre, randomised, controlled trials, the research group at St George's Hospital in London has persistently and systematically tested the concept of goal-directed haemodynamic management in high risk surgery in their single-centre setting. Their results have been impressive, demonstrating that in this setting, various outcome measures can be reduced with goal-directed haemodynamic management. The impressive positive results of the Pearse studies contrast sharply with the negative results of multicentre studies, such as that of Sandham et al. One reason may be that, like several other successful single-centre trials, Pearse et al. used strict treatment protocols rather than guidelines. In addition, single-centre studies utilize their investigators' knowledge of their patients' risk profiles and familiarity with the care processes and infrastructures of their institutions. An understanding of the organisational and case-mix aspects of pre-, peri-and post-operative management is vital for planning multicentre trials of goal-directed management.