الفهرس 
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Abstract
Patients exposed to toxic substances frequently present with respiratory complaints. Pulmonary manifestations of drug or chemical exposure can be acute, subacute, or chronic. They can be the consequences of direct toxicity of the compound or the result of indirect effects.
The aim of the present study was to determine the frequency of chest disorders in poisoned patients, to assess the severity of toxic induced respiratory disorders and the need for intensive care unit management, and to find out relation between different toxins and occurrence of acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) and their morbidity and mortality.
The study was carried out on 100 patients suffering from acute respiratory symptoms after exposure to toxic substances or drug overdose who were admitted to Alexandria Poisons Treatment Unit or Critical Care Medicine Department.
All cases were subjected to thorough history, physical examination, arterial blood gases, x-ray chest, and important laboratory investigation.
The most frequent respiratory disorders that found in our study were pulmonary aspiration, bronchospasm, non cardiogenic pulmonary edema (ARDS), pneumonia, neuromuscular weakness, and altered cellular use of oxygen.
The major toxins or drugs that found related to respiratory disorders in our study were the following: organophosphorus poisoning (OPP) 51%, carbon monoxide (CO) 10%, kerosene 10%, chlorine (hydrochloric acid) 5%, opiates 6%, tricyclic antidepressants (TCA) 5%, chlorpromazine 2%, baclofen 2%, hydrogen peroxide 2%, sulfuric acid 2%, cyanide 2%, botulism 2%, and snake bite 1%.
Organophosphorus poisoning was the commonest poison that found related to respiratory problems (51%) due to higher incidence of occurrence of OPP in Egypt. Respiratory distress in children was mostly due to accidental kerosene, or chlorine ingestion, and less frequently due to OPP.
Age of patients ranged from 2-47 years with a mean age of 21±14.25 years. The majority of cases were in the age group 25-35 and 15-25 years (25%, 22% respectively), followed by children below 5 years (20%). Male patients constituted 57 cases, while females accounted for 43 patients. There was no significant correlation between age or sex and outcome.
More than two thirds of cases were accidentally poisoned (68cases, 68%). Suicidal cases were 32 cases (32%) and more in females (17 cases).
Oral ingestion was the most common route of administration as in the solid granules of OPP (known as rat poison), liquids as kerosene, chlorine, hydrogen peroxide, or sulfuric acid, tablets as TCA (e.g. anafranil, tofranil), chlorpromazine (e.g. neurazine), or baclofen, and botulism in contaminated food. Inhalation comes next as in CO gas poisoning, cyanide powder, and some cases of OPP. Intravenous (IV) injection of dissolved powder was reported in opiate poisoning, skin contamination as in some cases of OPP, and skin bite as in snake bite.
Dyspnea was the most common symptom in the present study presented in about 76 cases (76%). Other complaints included bradypnea, salivation, sweating, vomiting, diarrhea, twitches (fasciculations), muscle weakness, dizziness, cyanosis, and sometimes convulsions, or abnormal movements, and others.
Miosis was a sign in all cases of OPP and opiates.
Most cases were presented with normal heart rate (68%) and blood pressure (79%). Bradycardia was only found in 16 cases (16%) from severe OPP associated with hypotension. Tachypnea was presented in 88% of cases. Deep breathing was accompanying tachypnea in about half of the cases (48%), while shallow breathing was found in 15% of cases. Normal temperature on admission was found in 79% of cases.
Fifty two patients required mechanical ventilation, while 48 cases needed oxygen mask with FiO2 40-60%, and few of them were put on endotracheal tube piece (T- piece) with FiO2 40-60%.
More than two thirds of patients (69%) presented with normal acid-base status. Twelve cases (12%) presented with respiratory acidosis while respiratory alkalosis was presented in 9% of cases. Metabolic acidosis was found in 6 cases due to lactic acidosis, or associated shock states, or in some poisons like TCA, while metabolic alkalosis was found in only 5% of cases. Hypoxia was presented in about one third of cases.
The majority of cases (88 cases, 88%) showed clinical improvement and discharged finally to home, while two cases (2%) ended by disability as in cases of OPP, and CO poisoning; both cases were transferred to Neurology Department. Ten cases died at the end of the study with a death rate of 10%.
Thirty nine cases (39%) exhibited no lung injury, followed by mild lung injury (32 cases), then moderate lung injury (22 cases), and lastly severe lung injury in 7% of cases. Six cases died in the severe lung injury group (85.7%), and four cases died in the moderate lung injury group (18.2%), while there were no deaths in the group of none or mild lung injury. All cases (100%) of severe lung injury (ARDS) in this study needed ICU admission, and about 82% of cases of moderate lung injury were also admitted to ICU. The overall ICU admission was 68 cases (68%). There was a significant relation between degree of lung injury and both ICU admission and outcome.
Ten cases showed four patches of infiltration; 5 cases of them died (50%), and 5 survived (50%), while 13 cases showed three patches of infiltration; 3 of them died (23.1%), and 10 survived (76.9%), and 22 cases showed two patches of infiltration; 2 of them died (9.1%), and 20 survived (90.9%). Fifteen cases showed one patch of infiltration and all survived (100%), and finally, 40 cases showed no patches of infiltration and also all survived (100%). This demonstrates that there was a significant relation between chest x-ray finding (number of patches of infiltration) and mortality rate.
Three cases presented with O2 index < 100, and all of them died (100%), while 8 cases presented with O2 index 100-174; four of them died (50%) and four survived (50%), and 15 cases presented with O2 index 175-224; three of them died (20%) and twelve survived (80%). 34 cases presented with O2 index 225-299 and all survived (100%), and finally, 40 cases presented with O2 index ≥ 300 and also all survived (100%). This demonstrates that there was a significant relation between O2 index and mortality rate.
PEFR and PEmax on admission couldn’t be done to half of the cases, but with improvement of the clinical condition more patients were able to do the two tests with significantly higher values compared to admission values.
Six cases died from 51 cases of OPP with percentage of 11.8%. This study found that the liquid form that is known as toxaphene is the most dangerous form in Egypt. The causes of death were refractory hypoxemia from ARDS, aspiration pneumonia, atelectasis, uncorrected metabolic acidosis, and severe myopathy. One case died due to cardiac arrhythmia and another one from septic shock. One case died from each following; 10 cases of kerosene (10%), 5 cases of TCA (20%), 2 cases of chlorpromazine (50%), and 2 cases of cyanide poisoning (50%). Cases of poisoning with CO, chlorine, opiates, baclofen, hydrogen peroxide, sulfuric acid, botulism, and snake bite all survived.
Low levels of pseudocholinesterase activity were found in most cases of OPP, and with increasing severity (cases of toxaphene poisoning), the pseudocholinesterase activity was markedly diminished.