IABP deployment in critical care

The Intra Aortic Balloon Pump (IABP) is an established support in addition to pharmacologic treatment of the failing heart after myocardial infarction, unstable angina, cardiac surgery and percutaneous coronary intervention (PCI). The indication for IABP in acute myocardial infarction expanded to include support of severely ill patient during acute cardiac catheterization and myocardial revascularization both percutaneous and surgical. An international randomized trial, SHould we emergently revascularized Occluded Coronaries for cardiogenic shocK? (SHOCK) reported that cardiogenic shock patients treated with the combination of IABP support followed by early angiography and myocardial revascularization, and/ or thrombolytic therapy had the lowest observed inhospital mortality. The Benchmark Registry revealed plausible IABP economic benefits in total hospital costs; whereas, the potential benefits of careful use of IABP therapy are unlikely to be offset by vascular and hemorrhagic complications. The inference, whether IABP can be appropriate initial therapy at hospitals without revascularization facilities, if followed by prompt transfer to tertiary centers in the developing world, requires careful assessment.


Authors:

Lactate is the ultimate oxidative energy substrate in brain and elsewhere

Now-a-days, the focus on lactate is due to its being an oxidative substrate for energy metabolism in brain (and other tissues), rather than a useless end product of anaerobic glycolysis. Mounting evidence indicates that lactate does play a major role in aerobic energy metabolism in the brain, the heart, skeletal muscle and possibly in any other tissue and organ. Nevertheless, this evidence has challenged the old concept of lactate being an anaerobic waste product and ignited a fierce debate between the supporters of glucose as the major oxidative energy substrate and those who support lactate as a possible alternative to glucose under certain conditions. While researchers working on energy metabolism in skeletal muscle have taken great strides toward bridging between these two extreme positions, accepting lactate role as an oxidative energy substrate, neuroscientists appear to be somewhat more emotional about their differences and less agreeable. In this paper I have employed findings from research on skeletal muscle along with the existing old and new data on cerebral energy metabolism, to postulate that lactate is the only major product of cerebral (and other tissues) glycolysis, whether aerobic or anaerobic, neuronal or astrocytic, under rest or during activation. Accordingly, lactate is a major, if not the only, substrate used by the mitochondrial tricarboxylic acid cycle. If proven true, this hypothesis should provide a better understanding of the biochemistry and physiology of (cerebral) energy metabolism and hold important implications where neuroimaging is concerned.


Authors:

Spontaneous breathing during mechanical ventilation in ARDS

The objective of mechanical ventilation used in the management of Acute Respiratory Distress Syndrome (ARDS) is to ensure adequate tissue oxygenation and alveolar ventilation while limiting the patients’ work of breathing and preventing further damage to the lungs. Although the “partial support” ventilation modes were initially developed to assist weaning or liberation from supported ventilation, they have gained increasing popularity as primary ventilation modes, even in patients in with severe acute pulmonary dysfunction. Allowing spontaneous breathing is known to alter both lung mechanics and physiological effects of ventilation, therefore has potential influence on important patho-physiological changes and complications that occur. Spontaneous ventilation has the potential to improve outcomes in ARDS, and therefore is worthy of an intensivist’s attention. A clinical trial of the use of pharmaceutical paralysis suggest a protective effect against worsening respiratory failure by ablating spontaneous breathing in ARDS. Overdistension of alveoli, even at low ventilator driving pressures may be as dangerous as high tidal volume (TV) controlled ventilation and thus naïve use of unrestricted spontaneous breathing techniques may be detrimental. As evidence of both improvement and deterioration exist the hypothesis remains controversial, and warrants a properly conducted randomised trial.


Authors:

Is there any need for higher PEEP levels in ARDS patients?

Lung protective ventilation has been shown to reduce mortality in ARDS patients. Current guidelines are focussed on lowering tidal volumes and minimizing mean airway pressures. In this review we discuss possible future improvements to mechanical ventilation; especially the open lung maneuver. We discuss the rationale for the use of higher PEEP levels in ARDS patients, using data from animal and human studies. Finally, guidelines for future strategies and/ or investigations are presented.


Authors:

Fluid resuscitation: the good, the bad and the ugly

Fluid resuscitation is one of the most common therapeutic steps in the critically ill. In this brief overview, the goals and potential adverse effects of fluid resuscitation are addressed. The contention is that the value of many of the fluid resuscitation goals in hypovolemic patients has not been unequivocally established, that overhydration is a significant problem and that certain types of fluids can be associated with major adverse effects. Hence, fluid loading should be carefully done and adequately monitored to avoid these effects and to improve survival of patients with hypovolemia and hemodynamic insufficiency.


Authors:

Pyrexia in the critically ill

Temperature change is a conserved physiological response to infection. In animal studies cytokine responses associated with body temperature changes have been elucidated. In humans with sepsis, hypothermia appears to be associated with higher TNF-alpha concentrations and has a significantly higher mortality. However, the presence of pyrexia does not appear to influence outcome from infection. The routine use of antipyretic agents remains controversial and studies in patients with viral infections suggest that their use may be associated with an anti-inflammatory effect with prolonged time to viral clearance – and surprisingly, little evidence of improvement in symptoms. In one ICU study it would seem that ibuprofen when used in the sub-group of patients with hypothermia and sepsis is associated with an improvement in outcome.


Authors:

Hypoxic tissue damage and the protective effects of therapeutic hypothermia

Several molecules, chemicals and cells are involved in tissue damage during any hypoxic event, such as a cardiac arrest, a respiratory arrest or a cerebrovascular accident. Among them: calcium, protein kinase enzymes, calcium binding proteins, S-100â protein and adhesion molecules such as intracellular adhesion molecule-1 (ICAM-1) are frequently cited in the literature. Controversy exists as to whether these “hypoxic aggressors” can be modified favorably by the use of therapeutic hypothermia. This review focus on the role of these different molecules, chemicals and cells and the protective effect of therapeutic hypothermia.


Authors:

Life-threatening hyponatremia in marathon runners: The Varon-Ayus syndrome revisited

Life-threatening hyponatremia can occur when sodium concentration falls to 125 mmol/L or less. Symptoms usually do not depend on the absolute sodium concentration but on the rate of fall. Estimates of mortality in acute hyponatremia are as high as 50%. Marathon runners are at particular risk of developing a syndrome which consists of severe hyponatremia, pulmonary edema and cerebral edema as originally described by Varon and Ayus. This syndrome, if not managed appropriately has a very high morbidity and mortality.


Authors:

Continuous renal replacement therapy in intensive care unit

Acute renal failure (ARF) requiring dialysis is a common complication of patients in intensive care unit (ICU). Dialysis can be performed with either intermittent hemodialysis (IHD) or continuous renal replacement therapy (CRRT). CRRT is associated with less hemodynamic instability. Therefore, it is preferred in critically ill and hypotensive patients in ICU. However, current evidence does not demonstrate the superiority of CRRT over IHD. Both methods for renal replacement therapy are complementary and the choice of dialysis in ICU should be individualized based on hemodynamic stability of patients and local expertise.


Authors:

“Natural catastrophes: Disaster management and implications for the acute care practitioner”

The year 2004 shook the world with earthquakes, hurricanes and Tsunamis in a way we would never imagine. Thousands of people died, were injured, missing or became homeless. Government agencies, health-care associations and citizens in general take part in planning for emergency preparedness and action when a natural disaster strikes a geographical area in such a devastating way. International humanitarian associations also participate in offering relief to the regions most critically affected. Hospitals and health-care organizations play an important role during these disaster and emergency situations. It is their duty to provide an efficient response in mass-casualty situations during natural catastrophes. For this reason, hospitals invest substantial efforts in developing disaster preparedness plans and training in coordination with public health systems and government agencies. Natural disasters impact a population in various ways. The victims’ environment may be severely affected compromising their resources and immediate needs such as food, water and their homes becoming an emotionally traumatic event for them. This significant change can also result in disease outbreaks. It is a challenge for health professionals to provide the most organized emergency response to benefit of humankind.


Authors:

Unstable angina and non-ST-segment elevation myocardial infarction

Coronary artery disease remains the most common cause of death in the world. Acute coronary syndromes, including unstable angina and non-ST-elevation myocardial infarction are commonly seen by critical care specialists. This article reviews up-to-date information on the diagnosis and state-of-the-art treatment of this condition.


Authors:

The difficult airway in critical care

Airway management with orotracheal intubation is one of the basic skills of a critical care practitioner. The oral route is the most common and easily mastered approach for tracheal intubation. Routinely, this technique involves visualization of the glottis, the use of a laryngoscope, and passage of the endotracheal tube into the trachea under direct vision. In many instances, this technique cannot be accomplished and the clinician needs to access the airway utilizing a variety of techniques. The patient with a difficult airway represents a significant problem for health care providers dealing with critical situations. This article describes some of the common approaches that can be used when a difficult airway is present.


Authors:

Effects of dexamethasone on lipopolysaccharide-induced expression of tissue factor, thrombomodulin and protein S on human umbili

Background: Previous reports about the effect of dexamethasone on LPS-induced expression of TF on endothelial cells obtained conflicting results. It was also unclear if dexamethasone could influence LPSinduced expression of TM and PS on endothelial cells. Objective: We re-examined the effects of dexamethasone on LPS-induced expression of TF, TM and PS on HUVEC. Methods: Human umbilical vein endothelial cells in their first to fifth passage were incubated with LPS in serum free medium with or without DEX. After incubation for indicated time, the cells were lysed. The protein levels of TF, TM and PS in the supernatant of the lysates were measured by enzyme-linked immunosorbant assay. Results: The LPS-induced expression of TF in HUVEC was time-dependent and dose-dependent. DEX could counteract the up-regulation effect of LPS (0.1µg/ml) on TF expression. 0.5ìg/ml and 1.0µg/ml DEX made the amount of TF expression decrease from 128.3 ± 25.7 pg/105 cells to 94.9 ± 19.4 pg/105 cells and 98.8 ± 7.8 pg/105 cells respectively (P<0.05). LPS could down-regulate TM expression in HUVEC in a timedependent and dose-dependent manner. The LPS-induced TM expression increased from 0.282±0.014 ng/ 105 cells to 0.409±0.009 ng/105 cells, 0.462±0.017 ng/ 105 cells and 0.362±0.019 ng/105 cells when 0.1µg/ml, 0.5µg/ml and 1.0µg/ml DEX was added respectively. When incubated with LPS (0.1µg/ml), the expression of PS in HUVEC was declining with the prolongation of the incubation time. The level of PS in lysate decreased to 20% and 17% of the control level at 1 hour and 4 hours respectively (P<0.01). DEX could also partially counteract the down-regulation effects of LPS on PS expression. When co-incubated with LPS (0.1µg/ml), DEX (0.5µg/ml) could increase PS expression from13.1 ± 4.8 % per 2×105 cells to 48.5 ± 10.2% per 2×105 cells (P<0.01). Conclusions: LPS could up-regulate the expression of TF and down-regulate the expression of TM and PS in HUVEC in vitro. These effects can be partially counteracted by DEX.


Authors:

Noninvasive ventilation

Noninvasive Positive Pressure Ventilation (NIMV) has significantly changed the approach to respiratory failure in the last two decades. NIMV has found increasing applications and widespread acceptability. It has proven value in reducing the intubation rate, mortality and length of hospital stay in acute decompensations in patients of chronic obstructive pulmonary disease (COPD). NIMV has been applied for respiratory failure in a wide variety of acute and chronic respiratory conditions where its beneficial effects are yet to be established. There are clear indications that NIMV may expedite weaning from mechanical ventilation in a substantial proportion of COPD patients. NIMV is shown to be easy to apply even in non-ICU setting by trained nursing and paramedical personnel. The past decade has witnessed improving technology of the noninvasive ventilation devices, as well as mask design and material. Several questions on the application of NIMV remain such as its precise role in conditions other than COPD, early markers of failure, and the timing of the application.


Authors:

A journey through the severe acute respiratory syndrome (SARS) crisis in Singapore – Observations of an intensivist

Singapore was the fifth most severely SARS (severe acute respiratory syndrome) afflicted country with 238 cases after China (5327), Hong Kong (1755), Taiwan (346) and Canada (251) [1]. On 31 May 2003, Singapore was declared SARS free by World Health Organization (WHO). The last SARS patient was discharged on 13 Jul 2003. The case fatality rate in Singapore was 13.9% (33/238), which was comparable to Canada 17.1%, Hong Kong 17.0%, Vietnam 12.7%, Taiwan 10.7% and China 6.6%. The global case fatality rate was 9.6% (774/8098). In September 2003, Singapore reported the world’s first laboratory-acquired SARS case [2,3]. Fortunately, this patient did well and did not result in any secondary cases. This review chronicles the journey through the SARS crisis in Singapore. It also interpolates the emotional challenges faced by the healthcare workers, an aspect that has not been well documented in the literature. In addition, our experience from battling this SARS epidemic may provide useful information to those who have to deal with such easily transmissible and potentially fatal infection in future.


Authors: