Flash n°10 – Monitoring and Automation

Flash n°10 – Monitoring and Automation

  • Issue 61

George Litarczek | Romania

Monitoring means continuous supervision of a process. A patient under ananaesthetic procedure must be monitored uninterruptedly from the first injection
or/and administration of pre-anaesthetic medication until they leave the territory of the postoperative recovery area or the intensive care ward.

Monitoring, like all processes of patient inspection, has two aspects: clinical examination and instrumental surveillance. The process starts with clinical supervision and observation when precious data on deleterious events are collected, offering data for many corrective measures performed in severe clinical conditions. This data constitutes a basic luggage of knowledge concerning the patient’s situation and also lead to solutions to life threatening problems.

Clinical monitoring in anaesthesia and intensive care was performed even in times where no electronic monitoring existed. Formerly the presence of sufficient and adequately trained personal was mandatory as was the permanent commitment  of the staff.

From 1846, “the Morton year”, to the late 1940s monitoring was routine. Thermometer (1866 T.C.Allbutt), stethoscope (1816 Laenec, 1840 Bird) and blood pressure measuring devices (1881 Karl Ritter von Basch, 1896 Scipione Riva – Rocci, 1905 Nikolai Korotkoff) represented the only instrumental help to clinical observation performed by the doctor, using observation, hearing (auscultation), touching (palpation, pulse checking), even smelling. However, continuous observation becomes monotonous; attention fades till the moment a critical event acutely explodes or insinuates itself progressively,. For most situations this precarious arsenal was considered sufficient, but in fact it lead a number of accidents. Death occurred in a too high proportion, mainly in the postoperative period, exactly in those moments of lesser presence of medical staff.

The situation only began to improve in the late 1940s, with the institution of postoperative wards, the introduction of respiratory resuscitation rooms and later in the 60s with the generalisation of postoperative and intensive care wards. These improvements were made in parallel with the introduction of new mechanical, electric and electronic equipment. The first category included respirators equipped with pressure and volume, measuring devices. By the end of the 1940s, a new instrumental trend offered some mechanical or electric/electronic systems connected to the patient, which ensured an uninterrupted monitoring process of one or more parameters and an alarm signal if a dangerous event occurred. The first monitoring device I know of is McKesson’s “Narcometer” ananaesthesia machine with “on demand” gas flow which recorded respiration parameters on paper, in fact a real graphic spirometer.

I will describe the next stage development in this direction based on my own experience. It took place during when I was at the beginning of my medical career in a hospital. I first entered  an active member in a surgical team in 1947.  The first task I was charged with was the administration of anaesthesia, using ether with the Ombredanne (a rebreathing mask, see previous flashes) and Narconumal (an oxybarbiturate)  as a sole i-v anaesthetic. Monitoring during such an adventurous enterprise was rather limited, as both hands were busy with the Ombredanne and/or the syringe.
The only option was to monitor  the drape covered patient by sight. In 1950 I was appointed to  one of the best surgical departments in Bucharest, Romania, where I was again in charge of anaesthesia, however the situation was different. I was asked to put in function and use a machine recently imported from the USA:a Forregger, model Texas with a Sword breathing system which included no less than three monitoring devices: a stethoscope which could also be fixed to the arm to be used in conjunction with a Riva-Rocci blood pressure manometer,  and a water manometer connected to the breathing system to measure, and at the same time limit the pressure in the respiratory system. These were the first monitoring devices mounted on an anaesthesia machine. In the following years some special monitoring devices were progressively introduced. The first was an ECG single trace monitor, to be used for cardiac surgical patients followed by an electric (bi-metal with a micro galvanometer) thermometer, anoxymeter (Millikan) which provided rather relative readings. The first polygraph was introduced in 1957,  a 4 -trace device with EEG, ECG channels, a mechanical pulse detector and two pressure transducers used for invasive arterial and venous pressure measuring. This equipment was reserved for anaesthesia in cardiac surgery, especially under moderate hypothermia.

In the early 60s we also received a capnograph (CO2 measuring device), and a Narcometer (measuring ether and halothane concentration in the inspired air), both used infrared photometry, as well as an Oxytest (O2 percentage measuring device).  We could measure the patient’s parameters and  control the anaesthetic circuit. Blood loss was also determined either gravimetrically (by weighing blood soaked swabs), or by washing surgical swabs  and determining either Hb or resistivity in the washing water).Eventually the whole system of monitoring was built up in different modules (EEG, ECG, temperature, pulse, invasive blood pressure, CO2, O2), all housed in a  big “cupboard”, located in the operating room. The first multi-channel monitoring device was conceived in the early 60s by Heinz Oehmig, a German anaesthesiologist. The 1950s and the 1960s saw the appearance of O2 (Clark) and CO2 (Severinghaus) measuring electrodes for blood samples or even transcutaneous measurements. Progressively, electronic components were smaller and consequently devices also became less and less cumbersome.  Embryonic types of software driven devices appeared in the 80s which included a computing system aimed to control the device. This development had two consequences:

1. The possibility to gather data eg: control of respiration, modern imaging devices such as CT and MRI, modules of non-invasive BP measurement (small but reliable), cardiac output measurement, echographs measuring intra vascular and intra cardiac flow and pressure, ST analysis, calculation of derived haemodynamic parameters, calibrated pulse oxymeters, and many other systems, incorporated  in the anaesthesia machine, like flowmeters, vaporizers and sophisticated ventilators.

2. The need for miniaturization.  eg the pulse oxymeter was the size of a cupboard and is now the size . Similar developments occurred in almost all of the monitoring devices in use today.

Today, monitoring is a compulsory activity, imposed by law in many countries, thus helping qualified personal in their routine work. Patient safety is tremendously improved and offers the clinicians reliable online data regarding the patient’s condition. Nobody could imagine provision of anesthesia or management of a critically ill patient in the absence of basic monitoring equipment. To end, I would like to mention another field which has made significant progress in the last years: the automation processes running under self control, like a car running without a driver. This kind of revolution is still in early stages but the future will show its positive impact. We already have syringes delivering drugs based on pharmacokinetic profile, anaesthesia machines performing routinely “Target Controlled Anaesthesia” and models of closed loop anaesthesia, in which the injection of an anaesthetic is controlled by computed EEG parameters (such as Median, Edge Frequency, BIS). There is no question that the future will be full of positive surprises for the clinical anaesthesiologist.