Paracetamol in fever in critically ill patients-an update.

Fever, which is arbitrary defined as an increase in body temperature above 38.3°C, can affect up to 90% of patients admitted in intensive care unit. Induction of fever is mediated by the release of pyrogenic cytokines (tumor necrosis factor α, interleukin 1, interleukin 6, and interferons). Fever is associated with increased length of stay in intensive care unit and with a worse outcome in some subgroups of patients (mainly neurocritically ill patients). Although fever can increase oxygen consumption in unstable patients, on the contrary, it can activate physiologic systems that are involved in pathogens clearance. Treatments to reduce fever include the use of antipyretics. Thus, the reduction of fever might reduce the ability to develop an efficient host response. This balance, between harms and benefits, has to be taken into account every time we decide to treat or not to treat fever in a given patient. Among the antipyretics, paracetamol is one of the most common used. Paracetamol is a synthetic, nonopioid, centrally acting analgesic, and antipyretic drug. Its antipyretic effect occurs because it inhibits cyclooxygenase-3 and the prostaglandin synthesis, within the central nervous system, resetting the hypothalamic heat-regulation center. In this clinical review, we will summarize the use of paracetamol as antipyretic in critically ill patients (sepsis, trauma, neurological, and medical).

Ventilator-related causes of lung injury: the mechanical power.

PURPOSE: We hypothesized that the ventilator-related causes of lung injury may be unified in a single variable: the mechanical power. We assessed whether the mechanical power measured by the pressure-volume loops can be computed from its components: tidal volume (TV)/driving pressure (∆P aw), flow, positive end-expiratory pressure (PEEP), and respiratory rate (RR). If so, the relative contributions of each variable to the mechanical power can be estimated. METHODS: We computed the mechanical power by multiplying each component of the equation of motion by the variation of volume and RR: [Formula: see text]where ∆V is the tidal volume, ELrs is the elastance of the respiratory system, I:E is the inspiratory-to-expiratory time ratio, and R aw is the airway resistance. In 30 patients with normal lungs and in 50 ARDS patients, mechanical power was computed via the power equation and measured from the dynamic pressure-volume curve at 5 and 15 cmH2O PEEP and 6, 8, 10, and 12 ml/kg TV. We then computed the effects of the individual component variables on the mechanical power. RESULTS: Computed and measured mechanical powers were similar at 5 and 15 cmH2O PEEP both in normal subjects and in ARDS patients (slopes = 0.96, 1.06, 1.01, 1.12 respectively, R (2) > 0.96 and p < 0.0001 for all). The mechanical power increases exponentially with TV, ∆P aw, and flow (exponent = 2) as well as with RR (exponent = 1.4) and linearly with PEEP. CONCLUSIONS: The mechanical power equation may help estimate the contribution of the different ventilator-related causes of lung injury and of their variations. The equation can be easily implemented in every ventilator's software.

[Skin reactivity in allergic conjunctivitis]. / Reactividad cutánea en conjuntivitis alérgica.

Allergic conjunctivitis is a very common disease in our country. We intend to determine the most frequent ocular involvement and the specific sensitivity to common aeroallergens. A longitudinal prospective study was performed on 20 patients from the allergy/immunology and ophthalmology outpatient service, Hospital Infantil de Mexico Federico Gomez, from May to July 1990. All of them had allergic conjunctivitis and were evaluated for ocular involvement and reactivity to common aeroallergens by skin prick test.

[Allergic conjunctivitis]. / Conjuntivitis alérgica.

The eye reacts to foreign substances through a variety of specific and non-specific defense mechanisms. Constantly exposed to a great variety of microorganisms, the eye is capable of protecting itself without altering its own structure and function. Its resistance relies upon anatomic and physiological properties of its external components (eyelids, tears, conjunctiva and cornea). Most of the times, the conjunctiva becomes affected, resulting in a clinical picture of conjunctivitis where allergy predominates, expressed as allergic rhinoconjunctivitis, allergic conjunctivitis, vernal keratoconjunctivitis, giant papillary conjunctivitis and flictenular conjunctivitis. The physiopathology is considered to be of type I reaction (IgE mediated). Frequent complains often associated with other allergic diseases are: pruritus, tearing, photofobia and ocular redness. The diagnosis of allergic conjunctivitis in done by means of a throughout clinical history, conjunctival citology and evaluation of specific IgE with immediate skin tests. Treatment is symptomatic (antihistamines, antibiotics and/or topic steroids), but prevention (environmental control and sodium cromoglycate) and specific immunotherapy must be considered.

[Skin response to the allergen of the roach in allergic patients]. / Respuesta cutánea al alergeno de la cucaracha en pacientes alérgicos.

Cockroach is an insect that is very frequent in urban areas. There are many research in the last years who shows the relationship between positive prick test to cockroach and respiratory allergy. We made a retrospective study with patient of the out patient clinic of allergy during July to December 1989, and who had a skin test to cockroach. We found a 27% positivities in the skin test, and most of the patients came from the urban area. The positivity of cockroach and dust mite were present in almost 80% of the patients.