Indian Journal of Surgery Medknow Publications on behalf of Association of Surgeons of India ISSN: 0972-2068 Vol. 65, Num. 3, 2003, pp. 228-231

Indian Journal of Surgery, Vol. 65, No. 3, May-June, 2003, pp. 228-231

Editorial

Critical care in surgery

Breach Candy Hospital and Research Centre. 60-A, Bhulabhai Desai Road, Mumbai 400026.
Address for correspondence Dr. Farokh E. Udwadia, Breach Candy Hospital and Research Centre. 60-A, Bhulabhai Desai Road, Mumbai 400026
Paper Received: April 2003. Paper Accepted: April 2003. Source of Support: Nil

Code Number: is03044

The surgical critical care unit originated in the recovery room of the operation theatre. Recovery rooms came into existence about 140 years ago. In 1863 Florence Nightingale wrote: "It is not uncommon in small country hospitals to have a small room leading from the operation theatre in which the patients remain until they have recovered or at least recovered from the immediate effects of the operation."¹ Under observation, the patients were protected from the adverse effects of anaesthesia and the surgical procedure.

Surgery has advanced thousandfold since the era of Florence Nightingale, aided by the phenomenal discoveries in the basic sciences and the revolutionary advances in biotechnology. The domain of surgery has flowered into numerous specialities and subspecialities, and the surgeon today can visit and touch every nook and corner of the human anatomy. This often requires major, extended, difficult surgical procedures under prolonged anaesthesia, necessitating expert patient care not only in the immediate postoperative phase, but also for a more extended period of time. The surgical critical care unit has thus evolved as a mere extension of the recovery room of the operation theatre.

The surgical critical care unit should be reserved for patients who undergo major surgical procedures inherently associated with a significant morbidity and mortality. Patients who undergo less major procedures, but who have serious background medical problems also deserve critical care. Important background medical problems include ischaemic heart disease, cerebrovascular disease, chronic bronchitis, emphysema, chronic renal insufficiency, diabetes, alcoholism, drug abuse and patients who are heavy smokers with impaired lung function. Seriously ill surgical patients, who though conservatively managed, warrant close observation, and those who require to be stabilized before surgery also need intensive care.

The majority of patients in a surgical Intensive Care Unit (ICU) are admitted for extended postoperative care. How critically ill a postoperative patient is or is likely to become depends on several factors the nature of and time taken over surgery, the nature and duration of anaesthesia, the age and condition of the patient prior to surgery, whether surgery involved entry and manipulation in a septic area, and whether the patient has serious background medical problems.

Major surgery in each speciality brings in its train its particular postoperative problems which the surgeon generally anticipates, detects and treats. However, there are some `universal problems' that can arise after any form of major surgery. These `universal problems' when considered in their totality, blunt the boundaries between medicine and surgery; they belong to both and that too in equal measure. These `universal problems' are briefly touched upon below.

Major surgery involves trauma, albeit purposefully directed, controlled and elegantly executed trauma. Trauma disturbs both the anatomy and the functions of various organ systems. Barring exceptions, a serious crisis in a patient soon after major surgery, is almost always related to the surgical procedure or its complications. This is the first premise in the approach to critical care in surgery.

The prime concern of the surgeon and the intensivist in postoperative care is to ensure that all organ systems are functioning well. Perhaps the most frequent and dangerous problem one encounters in the first few days after surgery is haemodynamic instability. Haemodynamic instability manifests as hypotension, inappropriate tachycardia, or both. Elderly patients may have a significant fall in blood pressure with little or no proportional increase in heart rate. This can be ominous as it denotes a lack of sympathetic drive, and therefore an inability to augment the cardiac output through an increase in the heart rate. On the other hand, in young individuals, tachycardia may be marked without a significant fall in blood pressure to start with, because of a powerful sympathetic drive. In these patients as haemodynamic instability worsens, the pressure can crash suddenly with disastrous consequences. It is important to detect haemodynamic instability in its early phase and determine its cause, as it may be the forerunner of severe shock. Unquestionably, the commonest cause is blood loss and / or fluid loss, which is often more than what the surgeon estimates. The peripheries of a patient in hypovolaemic shock are invariably cold and the neck veins collapsed. A central venous pressure (CVP) line is invaluable, and in my opinion mandatory in these patients, as it helps to guide blood and fluid replacement. The CVP should preferably be maintained between 7 and 10 cm H₂O. If venous pressure is satisfactory and the patient is still hypotensive, the surgeon and intensivist must look for other causes these include hypoxia (an O₂ saturation below 90 per cent), metabolic acidosis (easily determined from the arterial pH and blood gases), hypokalaemia, sepsis, and myocardial dysfunction. Myocardial dysfunction is not necessarily confined to cardiothoracic surgery it can complicate any major procedure, particularly in elderly individuals. Cardiac arrhythmias can also cause hypotension. An arrhythmia that is easily mistaken for sinus tachycardia is atrial flutter with a 2:1 block. Atrial flutter should always be suspected when the heart rate seems fixed around 150/minute. Finally, massive prolonged surgery is a form of trauma that can cause a systemic inflammatory response syndrome which can result in multiple organ dysfunction, haemodynamic instability and shock.

Critically ill surgical patients are unusually susceptible to atelectasis which is the basic mechanism of Type III or peri-operative respiratory failure.² Cardiothoracic surgery, major upper abdominal surgery and recumbency after any major surgical procedure, result in splinting of the diaphragm. The abnormal abdominal mechanics result in a reduced end-expiratory lung volume with a progressive collapse of dependent lung units. The end result is hypoxaemic (Type I) respiratory failure or ventilatory failure (Type II) or both. Clinically, peri-operative respiratory failure manifests with tachypnoea, and an x-ray of the chest showing raised diaphragmatic domes and `small lungs'. The `smallness' is not always symmetrical, one lung being at times smaller than the other. `Shadows' in the lung fields are not necessarily present in the chest x-ray. If unrecognized and uncorrected, the PaO<sub>2</sub> falls with or without a rise in the PaCO<sub>2</sub>. Identification of atelectasis as the cause of peri-operative respiratory failure (or for that matter, of respiratory failure in a critically ill surgical patient not subject to surgery) helps to both prevent and treat this important complication. Prevention is by frequent change in posture, physiotherapy to expand atelectatic areas, relief of incisional or abdominal pain, and draining of ascitic fluid, if present. If atelectasis persists and the lungs remain `small', non-invasive ventilation is indicated. If non-invasive ventilation fails to expand the lungs and reverse respiratory failure, the patient needs to be intubated and placed on mechanical ventilator support with an appropriate positive end expiratory pressure (PEEP) to help re-expand the lungs.

The importance of ventilatory support in critically ill surgical patients cannot be overemphasized. Ventilatory support is indicated not only in acute respiratory failure (with a PaO₂ < 60 mm Hg and/or a PaCO₂ > 50 mm Hg) but also electively in those with severe respiratory distress, even if arterial blood gases are normal. Thus a critically ill patient whose respiratory rate is greater than 35/ minute or whose minute ventilation exceeds 12 l/min needs elective intubation and ventilation. If this is not done, sudden respiratory arrest due to increasing respiratory muscle fatigue is likely. Ventilator support rests fatigued respiratory muscles, sharply decreases the oxygen cost of breathing, thereby releasing more oxygen for the vital organs such as the heart, brain and the kidneys.

The importance of measuring hourly or two hourly urine output in the initial postoperative period (for 2 days or more) cannot be overemphasized. One should aim at a urine output of greater than 60 ml/hour; a careful fluid balance chart should be maintained. Renal dysfunction is commonly due to pre-renal causes or due to drugs - for example, after blood loss, hypovolaemia, sepsis, nephrotoxic antibiotics and overuse of non-steroidal anti-inflammatory drugs for pain relief. Good renal function is of immense value in the management of the patient, as it allows a leeway for the manipulation of fluid therapy, particularly in haemodynamically compromised individuals.

Surgical shock is a dreaded feature in critically ill surgical patients. It is generally related to hypovolaemia, sepsis, trauma inflicted by the massiveness of surgery, or to a combination of the above. In patients who have a background of ischaemic or valvular heart disease it could be cardiogenic. Shock could be aggravated or at times caused by agonizing unrelieved pain. The surgeon may not realize this in a patient who is unable to communicate (as when on ventilator support). Shock should be looked upon as a state of acute circulatory failure leading to tissue hypoxaemia.³ Though hypotension is a feature of severe shock, the shock syndromes cannot be equated to hypotension, or to a fall in cardiac output, or to accompanying changes in circulatory haemodynamics. It is a major misconception that correction of hypotension and the restoration of a normal haemodynamic profile is the be-all and end-all in the management of severe shock. Shoemaker⁴ evaluated the significance of restored haemodynamic parameters in a series of critically ill survivors and non-survivors in surgical shock. He noted that with therapy the haemodynamic profile was restored to normal in 75 per cent of non-survivors. Death occurred in these patients in spite of restored haemodynamic parameters. Shock, in essence, is characterized by tissue hypoxia; it indeed lies buried within the tissues, and in the final analysis, it is the reversal of tissue hypoxia that reverses shock.³ Therapy which is adequate but delayed may be ineffective, for there comes in the natural history of shock a point beyond which there is no return.

Besides severe surgical shock, sepsis is the great killer in critically ill surgical patients. Sepsis is defined as the systemic inflammatory response syndrome due to infection.⁵ Severe sepsis is sepsis with hypoperfusion and/or dysfunction of one or more organ systems.⁵ Septic shock is sepsis associated with persistent fall in systolic blood pressure to less than 90 mm Hg in spite of adequate fluid replacement, together with hypoperfusion of tissues and dysfunction of one or more organs.⁵ The cause of sepsis needs to be unravelled and if found should be tackled as promptly and as best as possible. Sepsis could result from the surgical pathology causing the critical illness; it could be aggravated if the surgeon out of necessity has to enter a septic area. Sepsis could also be iatrogenic or nosocomial resulting from lines, drains, and ventilator support. Nosocomial pneumonia in itself may cause sepsis and septic shock; it has a high morbidity and a significantly increased mortality. Whatever the aetiology of sepsis, the importance of the prompt use of the appropriate antibiotics in the correct dose is of vital importance. The surgeon should familiarize himself with just a few effective antibiotics (together with their untoward effects), and learn to use appropriate combinations for different surgical situations. The wrong use of vancomycin is to be strongly deprecated.

Vancomycin should be reserved for proven infections caused by the methicillin-resistant staphylococcus or for life-threatening infections where the methicillin-resistant staphylococcus is the likely cause of surgical sepsis. The possibility of the staphylococcus ultimately becoming resistant to this drug through its improper use is too dreadful to contemplate. A major complication of unresolved sepsis, or rather its inherent feature, is the development of multiple organ dysfunction and failure. This is exemplified by the occurrence of the acute respiratory distress syndrome (ARDS), particularly after abdominal sepsis. ARDS is characterized by severe respiratory distress, diffuse shadows in both lungs, and severe arterial hypoxaemia which necessitates the use of ventilatory support. It has a mortality of 40 to 60 per cent. In bacterial sepsis, the development and persistence of three or more severe organ systems dysfunction is associated with a mortality of approximately 85 to 90 per cent.⁶ Remarkably enough, a severe failure of any one organ system (be it the heart, the lungs, the gut or the central nervous system) if irreversible or unrelieved, induces failure of other organ systems. This merely illustrates the holistic nature of the functioning of the human body. Organs literally talk to each other and the cells within each organ system do likewise. This is being slowly proven by molecular biology and when this communication between organ systems is truly unravelled we shall, probably in the distant future, gather the means to restore the deranged function of multiple organ systems. Till then we can only offer support, in the hope that time and nature effect a recovery.

There are a number of other `universal problems' in critically ill patients. They often lurk in the background; time and again they become serious enough to produce a sudden crisis. These include electrolyte disturbances, acid-base disturbances, subtle changes in the function of various organ systems which if unnoticed and uncared for spring a surprise on the unwary. Deep vein thrombosis with its attendant risk of pulmonary embolism is an ever-present threat to a critically ill patient. Here again, prevention is better than cure, and a high index of suspicion for venous thrombosis in the leg veins is often rewarding both to the patient and the surgeon.

There is also the ever-nagging prospect of a background disease erupting into violence following a surgical procedure or during any critical surgical illness. The most dangerous is the complication of a myocardial infarction, or a malignant arrhythmia, or a cerebrovascular accident in a surgical patient. It is wisdom to avoid elective major surgery in a patient with known ischaemic heart disease till the latter has been investigated with a coronary angiography and treated appropriately. Elective major surgery on a heavy smoker is preferably delayed for 4 weeks after the patient stops smoking.

Just as there are `universal problems' in critically ill surgical patients, there are `universal principles or ideals' for the caring surgeon or physician. They are difficult to achieve, one can only attempt to do so.

1. In this age of mind-boggling technology, the caring doctor must relate to his patient and not to the gadgetry that surrounds the patient. The eyes that know what to see, the ears that listen to the right sounds, the hands that are trained to feel, and the maturity and wisdom that should come from experience are far more important than all the gadgetry in high-tech units.
2. The caring surgeon should not only be aware (as much as possible) of what is happening to a critically ill patient, but should be a step ahead, so that he is aware of what is likely to happen next.
3. Disaster should be anticipated and if possible prevented; it should never be awaited.
4. Critical care requires a team. Yet, too many specialists, each doing his own bit, without regard to the overall perspective of the patient's illness can prove harmful. The team therefore should be orchestrated by a single individual who identifies and directs attention to the most emergent problems, while keeping a wary eye on those lurking in the background.
5. Every good surgical critical care unit requires a medical audit, so that morbidity and mortality within the unit can be assessed in relation to the severity of illness in the patients admitted to it.
6. The surgical critical care unit is a bastion of technology, but that does not make it a temple of care. It is only the professional skill and compassion of the doctors and nurses working within it that can convert a bastion into a temple.
7. It is important not to play God in the critical care unit. Yet one must not prolong the act of dying, nor make it hopelessly lonesome, terrifying, demeaning to the patient and ruinous to his family.

REFERENCES

1. Hilberman M. The evolution of the intensive care unit. Crit Care Med 1975;3:159-65.
2. Wood LH. The pathology and differential diagnosis of acute respiratory failure. In: Hall JB, Schmidt GA, Wood LH, eds. Principles of Critical Care. New York; McGraw-Hill: 1998. pp 499-507.
3. Udwadia FE. Overview of shock syndromes. In: Udwadia FE, editor. Principles of Critical Care. Delhi: Oxford University Press; 1995. pp. 107-10.
4. Shoemaker WC. Diagnosis and treatment of shock and circulatory dysfunction. In: Shoemaker WC, Ayres S, Grenvik A, Holbrook PR, eds. Textbook of Critical Care. 4th edn. Philadelphia: WB Saunders Company; 1998. pp. 92-114.
5. Bone RC, Balk RA, Cerra FB, Dellinger RP, Fein AM, Knaus WA, et al. Definitions for sepsis and organ failure and guidelines for the use of innovative therapies in sepsis. The ACCP/SCCM Consensus Conference Committee. American College of Chest Physicians/Society of Critical Care Medicine. Chest 1992;101:1644-55.
6. Knaus WA, Draper EA, Wagner DP, Zimmerman JE. Prognosis in acute organ-system failure. Ann Surg 1985;202: 685-93.

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