Bombay experience in intensive respiratory care over 6 years.SR Kamat, SS Heera, PV Potdar, SV Shah, NM Bhambure, AA Mahashur
The experience of the intensive respiratory care in 930 cases treated from 1983 for 4 years and in 404 cases over the next 2 years is reported. The background operational problems are stressed. Those between age 10 and 50 years did significantly better (p less than 0.05). The survival over the first 4 years in IPPR cases was 16.3% and in non IPPR group 71.8%; over the next 2 years, the former group, survival was 32.4 and 36.3%. The survival in asthmatic patients was high (76%). In cases with organophosphorus poisoning (without IPPR), survival was 81% while in IPPR group it was 29%. In 1988, the results in this group were better due to more aggressive management. In autopsy data on 85 cases, infection was not a major feature in those dying within 24 hours. The survival in COPD cases showed significant relation to age (p less than 0.05), initial arterial pO2 below 60 mm (p less than 0.01) and arterial pH below 7.3 (p less than 0.01). In cases with pneumonia (also asthma) younger cases did better (p less than 0.05) as also those with pneumonia and initial pO2 above 60 mm (p less than 0.01) and pH above 7.3 (p less than 0.001). When pneumonia was community acquired, survival (64.8%) was better than when it was hospital acquired (24%; p less than 0.01). Only the need for IPPR affected survival in trauma group. The major cause of death was infection with Klebsiella, Pseudomonas, Staphylococci and other gram--ve organisms. It is concluded that with proper planning and training, the IRCU does provide a useful mode of treatment in selected patients with respiratory problems.
Keywords: Adolescent, Adult, Child, Female, Human, India, epidemiology,Klebsiella Infections, epidemiology,Klebsiella pneumoniae, isolation &purification,Lung Diseases, epidemiology,etiology,microbiology,Male, Middle Age, Pseudomonas Infections, epidemiology,Respiratory Care Units, Respiratory Insufficiency, microbiology,Staphylococcal Infections, epidemiology,
Management of respiratory failure was poor till 20 years ago. Haphazard oxygen administration and airway suction were the only measures used in most cases. While artificial ventilation has been practised for over 50 years, long term respiratory assistance with physiological cover is less than 30 years old. In comparison to coronary or surgical intensive care units, intensive respiratory care involves isolation, tracheal intubation, correction of fluid imbalance, management of hypoxemia, replacement of breathing drive, cardiac support, airway toilet, chest physiotherapy, prevention of lung and systemic infections, control of respiratory muscle fatigue and failure, and management of neurologic dysfunction. All these make heavy demands and put mental stress on the institutional staff and lead to serious organisational problems e.g. ensuring constant oxygen supply, central suction and, nursing and ancillary training. Early experiences were reported by Moser et al and Petty et al. Both stressed the role of infection resulting in poor prognosis in intensive respiratory care. Though Moser et all reported that Streptococcus pneumoniae Haemophilus influenzae as common infecting organisms, others have reported Staph.aureus, Klebsiella, Pseudomonas and other gram -ve organisms as the major problems. Petty et al have reported an overall survival rate of 75.2% in such an intensive respiratory care unit (IRCU). Whereas post-operative and poisoning cases showed survival rates between 83 and 87%, those with chronic pulmonary diseases showed a less favourable outcome.
We report here our experience from 1983 to 1988 in managing such problems.
Though our intensive respiratory care unit was commissioned in 1981, its teething problems of providing central O2, supply, training of nurses, installation of respirators and monitoring equipments (Siemens Servo-Ventilator and lung function monitors) took several months. In 1988 we installed a liquid oxygen system. At this medical college hospital in central Bombay, most cases needing IRCU help are usually transferred from other units where a patient is admitted first. The transfer many times may be done at an advanced stage of respiratory failure. Sometimes an emergency service may choose to admit a new case directly into our unit. Irreversible, moribund cases with advanced neurologic damage are generally not taken up by us. Each patient referred for IRCU management is taken into a sterilised cubicle and monitored for fluid balance, physiotherapy, airway toilet with a management of hypoxemia and CO2 retention. This is supported by treatment of lung infection with appropriate antibacterial drugs. In case of hypoxemia and CO2 retention, when parenteral nikethamide and oxygen do not help to improve the patient, assisted ventilation (IPPR) is offered. The latter is provided by means of a Siemens Servo-Ventilator with variable pressure, flow and volume parameters. By repeated monitoring, adequate levels of minute ventilation, respiratory rate and gas exchange are maintained. The latter is crosschecked by estimating arterial blood gases 3-5 times daily. During the stay in IRCU, each patient is monitored every 15-30 minutes for all vital parameters such as pulse, blood pressure, respiration (rate and excursion), venous pressure, minute ventilation, airway pressure and resistance. In each patient, additional management is directed to correction of (i) other biochemical and clinical abnormalities, (ii) metabolic and fluid imbalance, (iii) cardiac support, (iv) airway toilet and (v) underlying general or chest disease with its complications. Tracheal and airway toilet is carried out aseptically with rubber or plastic catheters and with chest physiotherapy. After 3-7 days of endotracheal intubation, tracheostomy is usually performed to facilitate more effective airway toilet, or/and prevention of gastric aspiration. We always use porter low pressure cuffed tracheostomy tubes. Several times during IRCU treatment, sputum or tracheal secretions were cultured for organisms and drug sensitivity is determined for selecting appropriate antibacterial drugs. Polytherapy with multiple drugs and antibiotics is avoided, as far as possible.
The results are presented as basic causes, prominent presenting clinical and blood gas pictures, complications and some correlations. Statistical differences are worked out by chi square test.
[Table - 1]describes the study population for the years 1983 to 1986. Thus we treated an average of over 200 patients a year, who stayed in IRCU for periods of 7-10 days. The overall survival was 48%, being 16.3% for those on ventilator and 71.8% for those managed with conservative measures. Generally, the younger patients fared better than those older than 50 years. The survival rates were as follows:-below 10 years: 54%, between 11 and 50 years: 92% and beyond 50 years: 53% (p<0.05). The outcome was mainly influenced by the basic aetiology.
[Table - 2]represents the diagnostic categories of the entire group of patients. Thus, the largest group consisted of organophosphorus poisoning. The asthmatics showed the best survival rate (76% ). In comparison, in miscellaneous and chronic bronchitis categories, 55.7% and 51% survived. There were lower survival rates with trauma, ARDS, pneumonia and neurogenic paralysis. Not shown in the table, there was no difference in outcome by sex.
[Table - 3]lists the subcategories in neurogenic and miscellaneous groups. Sometimes, there were problems about clearly differentiating a motor polyneuropathy from poliomyelitis and most such cases proved to have elevated polio antibody titres. Broadly, survival rates varied with the duration of illness, etiology, need of IPPR and length of intensive care.
[Table - 4]illustrates results in cases with organophosphorus poisoning. In 50% patients IPPR was necessary. Those (31) who took other agents such as alcohol, barbiturates or a sedative, in addition, fared worse. We have seen a rising trend of using a longer acting agent from the organophosphorus group. The survival was 81% in those managed only with high dose of intravenous atropine, oxygen, correction of fluid imbalance, diuretics and airway toilet as compared to 29% in those who required IPPR. The mean duration of IPPR was 3 days and the maximum duration 23 days. We used atropine in large doses (6 mg/ml), given 2-4 ml every hour; on occasion as much as 400-900 mg had to be administered over 24 hours to keep pupils dilated. We took tachycardia beyond 150/min, twitching on the chin, high temperature (>39°C) or restlessness as the end point of adequate atropinisation. After the initial stomach wash, and treatment of pulmonary oedema (seen in 33% on admission and in 58.6% as a complication) with diuretics, dehydration, electrolyte imbalance and acidosis were the common problems. On regaining the consciousness the patients were usually rowdy, incoherent and full of misleading information. A proportion (10-15%) showed delayed re-excretion syndrome with hypoventilation, constricted pupils, increased need for further atropine, perspiration and hypotension. This required oxygen, diuretics and many times prolonged IPPR. The causes of hypotension and CO2 retention were usually IPPR and airway secretions. If a case comes off IPPR, or intensive care quickly (within 48 hours), usually a lung infection is not a problem. In a proportion of cases we identified the organophosphorus agent viz. fenitrothion (39), fenthion (38) and carbamate (33). The usual additional agent taken was alcohol (22), kerosene (6), barbiturate (2) and naphthalene (1).
There were 102 deaths. Autopsy data was analysed for 85 cases [Table - 5]. Those who died within 24 hrs of admission, exhibited interstitial oedema and haemorrhage in lungs. In those dying after 24 hours, consolidation and oedema were commonly seen. In a large proportion, brain showed the following abnormalities: herniation with coning, patchy congestion and oedema. Kidneys showed tubular degeneration, cloudy change and congestion; in 51%, the kidneys were normal. The liver was normal in 65.9% but showed fatty change or congestion in others. Thus the main causes of death were oedema of major organs (early) and lung infection (late). Because of effective management, widespread changes attributable to organ hypoxia were uncommon.
[Table - 6]shows results in COPD cases. As we had usually found bad results with IPPR in previous years, these patients were treated conservatively unless they had an additional complication such as neurologic paralysis. The treatment included nasal oxygen by catheter or by tracheal mask (with projecting catheter), airway toilet, anti-CCF and antibiotic treatment. We also used i.v. nikethamide 20 to 80 ml/24 hours as an analeptic regularly with a satisfactory control of CO2 retention. In less severe CO2 retention, oral acetazolamide 250-1000 mg/day resulted in faster improvement. We treated patients with pO2 as low as 19 mm, pCO2 as high as 130 mm, and pH as low as 7.1. Only in patients with methyl alcohol poisoning and renal acidosis we recorded pH below 6.5. Usually, deaths were due to hypotension, and infection. Many times, these patients were old, wasted and also had ischemic heart disease. In our experience, infrequent supraventricular premature beats were not uncommon but ventricular or frequent arrhythmias were rare. Therefore, we have rarely felt the need of constant cardiac monitoring unless the presenting feature was acute myocardial infarction. The survival showed a significant relationship with age below 50 years: 59.7% and above 50 years: 44.4% (p < 0.05) ; with initial pO2, below 60 mm: 51% and above 60 mm: 72.2% (p < 0.01) and with pH, above 7.3: 57.4% and below 7.3: 28.6% (p < 0.01). But the outcome was not related to sex, pCO2 or type of history of COPD (blue bloater or pink puffer).
The results in bronchial asthma are presented in[Table - 7]. In only 7 cases with CO2 retention, IPPR was given; of these 3 survived. In most cases, the presentation was hypoxemia, hypocapnia or metabolic acidosis. Only in 10-24% of the cases, these features were severe. Adequate injectable bronchodilators, correction of fluid and electrolyte imbalance, maintenance of blood pressure were important in these patients. Approximately in 50% of patients, we used corticosteroids and in 60% antibiotics were given in presence of high fever, leucocytosis and radiographic or clinical evidence of lung infection. Death was associated with hypotension and persistent hypoxemia.
[Table - 8]lists the results for acute pneumonia and ARDS. Both groups showed similar survival rates (upto 35.8%). As in asthma, survival in these 2 categories was significantly related to age (p < 0.05) but not to sex. Most ARDS patients were put on IPPR. The survival was significantly lower for pneumonia in presence of pO2 below 60 mm (39. 1% ) than in the presence of pO2 above 60 mm (78.9%) (p < 0.01); for pH below 7.3, 20% and 57.1% with pH above 7.3 (p < 0.001) and for Pseudomonas infection 20% against 57% in other Gram -ve infections and 80% in Gram +ve infections (p < 0.01). If pneumonia was reckoned to be community acquired, the survival was better (64.8%) than if it was hospital based (24%) (p < 0.01). The bacteriologic patterns of infections are shown in [Table - 13]The complications in both these groups were resistant infection, hypotension and for ARDS, hypoxemia as well.
[Table - 9]details data in patients with polyneuropathy. In 69.2%, IPPR was needed and was administered for a mean of 9 days. Generally younger patients had a better outcome. A few cases died suddenly inspite of stable parameters (n=5). In our experience, young myasthenic subjects, with preserved musculature fared better while on IPPR. In other cases, the original pathology usually decided the outcome as IPPR or other intensive management only served to buy time. In the neuroparalytic category, some regained respiratory drive but not adequate limb power. In cases with snakebite, those with cardiovascular shock fared worse. The cases which had involvement of brain or had multiple cranial nerve palsies, exhibited poor prognosis.
[Table - 10]lists the experience with trauma. The cases with spinal column fracture, multiple rib or bone injuries and associated cardiopulmonary disease were associated with poor prognosis. But, factors other than IPPR, did not influence the outcome. The common complications were persistent hypoxemia, infection and hypotension.
[Table - 11]briefly outlines experience in 1987. In 1987, 236 patients were treated, with a survival which is similar to that in the earlier period. The rate of survival was, however, higher (32.4%) for IPPR cases than in earlier years.
The data in 10 months of 1988, [Table - 12]have been analysed more extensively. These show that in both categories (IPPR and non-IPPR) survival rates have improved, particularly for organopbosphorus poisoning, wherein the mortality has diminished from 42.4% to 28.4%. This was mainly due to prompt transfer of cases from general wards to our area, more aggressive atropinisation and improved airway toilet procedures. The trend in neurogenic paralysis suggests a greater mortality in 1988 which may be attributed to the severity of illness. The age and sex patterns in all categories were similar to those in earlier years. The duration of IRCU management was longer for trauma and neurogenic paralysis. We have also shown a split up of miscellaneous cases which belong to disparate causes.
[Table - 13]and [Table - 14] show bacteriological results. Among Gram positive organisms, Staph. aureus and Str.pneumoniae were common and were best treated with erythromycin and chloramphenicol for the former and penicillin and erythromycin for the latter. The several strains listed indicate the changed pattern of complicating infections.
The microbiological pattern was similar for patients from general respiratory ward but in a significantly larger proportion (31% ) no pathogens were isolated. The drug sensitivities were similar. The frequency of other Gram -ve organisms was also lower.
Our results stress the need to inculcate close monitoring of various vital parameters, better facilities to prevent infections (by further improving barrier nursing) and need to encourage research in improved management of lung infections with resistant organisms. In our experience, for most Gram -ve organisms, gentamicin was most useful and for Gram positive bacteria, penicillin or erythromycin.
In a study from Italy on control of infections in intensive care units, Costantini et al have reported that such infections are very relevant to the outcome. The intensive care patients are more susceptible to infections due to their poor immune status, due to underlying diseases and numerous invasive diagnostic and therapeutic procedures. In their study of 859 patients, 44% developed infections. In these, pneumonias were common. In 92.3% cases, invasive procedures viz. tracheal intubation and IPPR were most contributory. The frequency and severity of infections were related to duration of hospitalisation. Gram -ve organisms accounted for 57% of their isolates. The prevalence in respiratory cases was the highest (77.8%).
Others, have reported similar prevalence and morbidity with predominance of Gram -ve organisms particularly Pseudomonas. We have found Klebsiella and Pseudomonas as the most frequent organisms causing lung infections. The infection by this group of organisms leads to deterioration of patients in IRCU, however the status of the predisposing disease may be equally important in determining the outcome. Thus in our series results were better with bronchial asthma and organophosphorus poisoning. Both these comparatively acute/intermittent conditions were commoner in younger persons. As the latter forms a large proportion of our load resulting in a nearly normal patient after a successful treatment, we feel this alone will justify an enhancement of intensive respiratory care facilities. In these, the dominant presentation was pulmonary oedema on admission and an unfavourable outcome was linked to lung oedema and hypoxemia. Our mortality cannot be compared with other earlier series, as our study population represents the most severe group, with different aetiologies. As interstitial lung oedema was the main finding (75%) in our autopsy data pertaining to organophosphorus poisoning, it is obvious that such patients die of acute generalised reaction to the agent.
Petty et al have reported 65% mortality with patients of chronic bronchitis over 1 year. Others have reported 24 to 35 mortality with intensive care treatment in such group of patients as compared to 52% in our series. Due to different circumstances, it is difficult to compare our rates of survival (28 to 76% ) with those in Western countries.
The ideal nurse-patient ratio, in advanced countries is 4:1, we have kept a working doctor-nurse-patient ratio of 1:3:1. We would consider close consultation and supervision by senior physician with dedicated follow-up action by junior doctors as the most important point in salvaging these difficult patients. It has been occasionally difficult to solve problems of oxygen supply, electric power supply, obtaining drug sensitivity patterns on tracheal secretions and tackling the low morale of staff over long holiday or week-end periods. We have saved only a few patients when brain death or severe brain damage (mainly following prolonged hypoxemia) was already established.
We delayed tracheostomy till 4-5th day of IPPR unless copious secretions and toilet problems leading to atelectasis or CO2 retention accelerated the decision. We did take extensive precautions in sterilisation of respirator parts, masks and suction accessories. We did not recommend wearing of full overalls but insisted on wearing of head cover, mask and slippers. Despite this, we have not been able to restrict usage of antibiotics in IRCU patients treated for longer than 48 hours and in IPPR patients longer than 24 hours. It seems that lung infection is the main cause of death with prolonged management as seen in our autopsy data of organophosphorus poisoning cases. Therefore, more practical ways of isolation and judicious use of advanced antibiotics may help in improving survival under such intensive care conditions.
In conclusion, our experience indicates a useful role for intensive respiratory care units. The problems still besetting us are late transfer of suitable patients, neurological or generally advanced damage to vital organs and drug resistant infections. In the earlier period, we also faced problems of trained manpower (nursing and medical), sudden electric power failure, difficulties in adequate oxygen supply and provision of 24 hour blood gas and biochemical measurements.
We thank Dr. G. B. Parulkar, Dean K.E.M. Hospital and Seth G.S. Medical College, for allowing this work to be published. We appreciate help of several residents who helped us to run this service and the help of bacteriology, biochemistry and blood laboratory staff particularly Dr. Smt. S. G. Kinare, Dr. Suit. S. P. Taskar, Smt. Pratima Hardikar, V. P. Kolhatkar, Dr. Smt. Ajita P. Mehta and Smt. A. Pinto.
[Table - 1], [Table - 2], [Table - 3], [Table - 4], [Table - 5], [Table - 6], [Table - 7], [Table - 8], [Table - 9], [Table - 10], [Table - 11], [Table - 12], [Table - 13], [Table - 14]