The pathophysiology and treatment of canine kerosene pulmonary injury: Effects of plasmapheresis and positive end-expiratory pressure

Severe acute respiratory distress syndrome caused by unintentional sewing machine lubricant ingestion: A case report

Sewing machine oil ingestion is rare but is possible due to its availability at home. Chemically, it belongs to hydrocarbon family which is toxic if aspirated, owing to their physical properties such as high volatility and low viscosity. On the contrary, sewing machine lubricant has high viscosity and low volatility which makes it aspiration less likely. The main danger of hydrocarbon ingestion is chemical pneumonitis which may be as severe as acute respiratory distress syndrome (ARDS). We report a case of a 5-year-old girl with accidental ingestion of sewing machine lubricant oil, who subsequently developed ARDS refractory to mechanical ventilation. There was much improvement with airway pressure release ventilation mode of ventilation, but the child succumbed to death due to pulmonary hemorrhage.

Early administration of intratracheal surfactant (calfactant) after hydrocarbon aspiration

Hydrocarbon ingestions account for a substantial number of accidental poisonings; when aspirated, it can lead to severe pneumonitis. Treatment for severe pneumonitis is generally supportive, and outcomes are frequently poor. We report here the case of a 19-month-old girl who was treated successfully with early administration of exogenous surfactant for acute respiratory distress syndrome secondary to aspiration of lamp oil. Approximately 7 hours after aspiration, she required mechanical ventilation and had an oxygenation index (OI) of 13.2. Approximately 10 hours after ingestion, exogenous surfactant (calfactant) was instilled intratracheally, after which her OI improved markedly to 4.3. She received a second dose ∼19 hours after ingestion, after which her OI remained at <5 and she was progressively weaned from mechanical ventilation. She was extubated 64 hours after the ingestion with no residual lung disease. This case illustrates the importance of considering exogenous surfactant therapy early in the course of acute respiratory failure secondary to hydrocarbon aspiration. Because of the putative mechanisms of lung injury involved in hydrocarbon aspiration, surfactant-replacement therapy is a reasonable therapeutic intervention based on pathophysiologic rationale.

A comparison among animal models of acute lung injury

OBJECTIVES

To compare four widely used animal models of acute lung injury and to determine the changes in physiologic variables associated with each model.

DESIGN

A prospective, controlled animal study.

SETTING

An animal laboratory of a university-affiliated children's hospital.

SUBJECTS

Four groups of anesthetized, paralyzed, and ventilated young Yorkshire pigs, weighing 35 to 45 kg.

INTERVENTIONS

Acute lung injury was generated by four different methods: a) intrapulmonary arterial infusion of endotoxin of Escherichia colt; b) bronchoalveolar instillation of 0.05N of hydrochloric acid; c) repeated bronchoalveolar warm saline lavage; and d) intrapulmonary arterial infusion of oleic acid. After each acute lung injury procedure, the temporal changes in various physiologic variables were measured, starting at 60 mins and at 15-min intervals thereafter for a total of 165 mins. Systemic and mixed venous serum immunoreactive tumor necrosis factor (TNF)-alpha concentrations were also measured at the same time points. Analysis of variance for repeated measures was employed to determine the absolute and relative significance of the changes observed.

MEASUREMENTS AND MAIN RESULTS

Systemic and mixed venous immunoreactive TNF-alpha did not change following any of the acute lung injury procedures. The animals' heart rates and systemic vascular resistances also did not change. Hydrochloric acid instillation as well as bronchoalveolar lavage resulted in significant hypoxemia with no other hemodynamic effects. Endotoxin infusion did not result in hypoxemia but caused significant increases in mean pulmonary arterial pressure and pulmonary vascular resistance and decreases in mean arterial pressure and cardiac output. Oleic acid infusion resulted in a marked hypoxemia with a pronounced increase in mean pulmonary arterial pressure and pulmonary vascular resistance. It also markedly reduced the mean arterial pressure, cardiac output, and the mixed venous PO2.

CONCLUSIONS

The surfactant depletion and hydrochloric acid instillation models produce acute hypoxemia in an otherwise hemodynamically stable animal. A brief endotoxin infusion provides a model for cardiovascular instability and pulmonary hypertension but fails to produce hypoxemia in the pig. The oleic acid infusion creates a model of marked cardiovascular instability, pulmonary hypertension, and profound hypoxemia. However, none of the acute lung injury models described was associated with the production of tumor necrosis factor.

Artificial surfactant for therapy in hydrocarbon-induced lung injury in sheep

OBJECTIVE

To document the effect of administering artificial surfactant into the trachea, either by instillation or aerosolization, on acute lung injury experimentally induced with kerosene in sheep.

DESIGN

Randomized, prospective, controlled study.

SETTING

Research laboratory.

SUBJECTS

Sheep (n = 24), weighing 8.5 to 25.2 kg (average 16.6).

INTERVENTIONS

In anesthetized, tracheally intubated sheep with pulmonary and femoral artery catheters inserted, lung injury was induced by instilling kerosene (0.3 mL/kg) into the trachea. After 15 mins of spontaneous breathing, mechanical ventilation was instituted with a uniform F10(2) and a tidal volume of 10 mL/kg. Sheep were then assigned randomly to one of four regimens as follows: exogenous surfactant or saline (5 mL/kg each) was administered as a bolus intratracheally or by aerosolization for 6 hrs.

MEASUREMENTS AND MAIN RESULTS

Arterial and mixed venous blood gases, pH, airway pressure, and static respiratory system compliance were measured and compared between aerosol saline and aerosol surfactant and between bolus saline and bolus surfactant. For all variables except static respiratory system compliance, the hourly rate of change from 15 mins, 1 hr, and 6 hrs after kerosene instillation was determined for each animal, and group rank sums of hourly rates of change were compared. For static respiratory system compliance, the slope of the pressure-volume curve with volumes of 100, 200, 300, 400, and 500 mL was computed for each animal at baseline and at 3 and 6 hrs after kerosene instillation. Group rank sums for static respiratory system compliance at 3 and 6 hrs were compared. Also, the 3- and 6-hr static respiratory system compliance values at each of the volumes were compared. With saline, six of eight sheep died; with surfactant, no sheep died (p = .001). When compared with saline at 15 mins, 1 hr, and 6 hrs after kerosene instillation, surfactant, regardless of whether administered by aerosol or bolus, significantly increased rate of change of arterial oxygen saturation, mixed venous oxygen saturation, and PO2.

CONCLUSIONS

In the present animal study, artificial surfactant was an effective treatment for hydrocarbon aspiration. Aerosolized surfactant achieved results similar to instilled surfactant but at a lower total dose.

Improved outcome based on fluid management in critically ill patients requiring pulmonary artery catheterization

We performed a randomized, prospective trial to evaluate whether fluid management that emphasized diuresis and fluid restriction in patients with pulmonary edema could affect the development or resolution of extravascular lung water (EVLW), as well as time on mechanical ventilation and time in the intensive care unit (ICU), in critically ill patients requiring pulmonary artery catheterization (PAC). PAC was performed on 101 patients. A total of 52 patients were randomized to an EVLW management group using a protocol based on bedside indicator-dilution measurements of EVLW. The other 49 patients were randomized to a wedge pressure (WP) management group in whom fluid management decisions were guided by WP measurements. A total of 89 patients had pulmonary edema (defined as EVLW greater than 7 ml/kg ideal body weight). Except for a clinically unimportant difference in mean age, the two groups were entirely comparable at baseline. The study groups were managed differently, as evidenced by cumulative input-output of 2,239 +/- 3,695 ml (median = 1,600 ml) in the WP group versus 142 +/- 3,632 ml (median = 754 ml) in the EVLW group (p = 0.001). EVLW decreased significantly, and ventilator-days and ICU days were significantly shorter only in patients from the EVLW group. No clinically significant adverse effect occurred as a result of following the EVLW group algorithm. Thus, a lower positive fluid balance, especially in patients with pulmonary edema regardless of cause, is associated with reduced EVLW, ventilator-days, and ICU days.

Fluid balance during pulmonary edema. Is fluid gain a marker or a cause of poor outcome?

STUDY OBJECTIVE

To evaluate the importance of fluid balance and changes in extravascular lung water (EVLW) on survival in the ICU and short-term outcome in patients with pulmonary edema.

DESIGN

Retrospective analysis of data (sorting by survival and "treatment received") from a recent randomized controlled trial of fluid restriction in this population.

SETTING

Medical ICU of a university-affiliated, tertiary-care medical center.

PATIENTS

Eighty-nine patients (from the previously mentioned study) requiring pulmonary artery catheterization with abnormally high EVLW (greater than 7 ml/kg).

MEASUREMENTS AND RESULTS

When analyzed by survival, the survivors had no significant fluid gain or change in EVLW but decreased wedge pressure and body weight, compared to nonsurvivors. When analyzed by fluid balance, patients who gained less than 1 L of fluid by 36 hours into the study had a better rate of survival (74 percent) than the rest (50 percent; p less than 0.05). Also, the median duration of days on the ventilator, ICU days, and days of hospitalization was approximately half as long for each variable in the group with less than 1 L of fluid gain. Even accounting for baseline differences in the severity of illness, fluid balance was an independent predictor of survival (p less than 0.05). When analyzed by whether or not EVLW decreased by more than 15 percent between the first and last measurement, only patients with ARDS or sepsis had decreased days on the ventilator and ICU days.

CONCLUSIONS

These data support the concept that positive fluid balance per se is at least partially responsible for poor outcome in patients with pulmonary edema and defend the strategy of attempting to achieve a negative fluid balance if tolerated hemodynamically.

Improved survival in ARDS patients associated with a reduction in pulmonary capillary wedge pressure

The survival and ICU length of stay of 40 ARDS patients admitted to the ICU were analyzed to determine if a management strategy of lowering the pulmonary capillary wedge pressure (Ppw) was associated with an increased survival or a decreased ICU length of stay. ARDS was defined as three or four quadrant alveolar filling roentgenographically, a PaO2 less than 80 mm Hg with an FIO2 greater than .5 and a Ppw less than 18 mm Hg. Patients were divided into two groups: group 1 included all patients in whom there was a reduction of Ppw by at least 25 percent, and group 2 included patients in whom there was no, or less than a 25 percent reduction in Ppw. Survival was statistically different between the groups with 12 of 16 group 1 patients and seven of 24 group 2 patients surviving to hospital discharge. This difference remained statistically significant after stratifying patients by age and the APACHE II severity of illness index. We conclude that this retrospective analysis supports the notion that treatment of low pressure pulmonary edema with reduction of Ppw is associated with an increased survival.