Main areas of monitoring
Patient safety in the operating room is ensured by strict control of key life-support systems. During general anesthesia, physicians are required to continuously assess several basic parameters.
Of paramount importance is hemodynamics. In routine practice, medical staff measure blood pressure (BP) and count heart rate (HR) at intervals of 10–15 minutes. However, there are special risk groups that require closer attention. If the patient has underlying cardiovascular diseases or is undergoing thoracic surgery, standards require continuous cardiac monitoring using electrocardiography (ECG).
In addition to heart and vascular function, monitoring includes the assessment of:
- Body temperature.
- Oxygenation (blood oxygen saturation).
- Renal excretory function (diuresis).
- Depth of anesthesia. Electroencephalography (EEG) may be used for precise control of consciousness suppression.
A critical aspect is the control of ventilation and metabolism. For this purpose, the acid-base balance (ABB) of the blood is examined. Physicians track oxygen tension (pO2), carbon dioxide tension (pCO2), hydrogen ion exponent (pH), and base excess or deficit (BE).
Criteria for adequate anesthesia
How to know that anesthesia is proceeding safely and analgesia is sufficient? The golden rule in anesthesiology is: a deviation in monitored parameters is considered acceptable if it remains within 20% of the patient's baseline level before the surgery begins.
Clinical and instrumental signs of adequate anesthesia include five main points:
- Hemodynamics: stable blood pressure levels without sharp surges and the complete absence of tachycardia.
- Skin condition: the patient's skin should have a normal color and remain naturally dry. The appearance of sweating is an alarming sign, often indicating an autonomic response due to inadequate analgesia.
- Diuresis: stable urine output, which should normally be 30–50 ml/h.
- Gas exchange: maintenance of normal saturation (adequate arterial blood oxygenation) and stable carbon dioxide content.
- ECG: normal heart rhythm parameters without ischemic or arrhythmic changes.
Maintenance of anesthetic records
All information about the course of anesthesia is strictly documented. The anesthetist nurse maintains a special anesthesia record, which is a crucial legal and medical document. Upon completion of all procedures, this form is added to the patient's medical history.
Mandatory recording of homeostasis parameters: Data on pulse, blood pressure, central venous pressure (CVP), and respiratory rate (RR) are continuously entered into the chart. All adjustable parameters of the mechanical ventilator are also recorded.
Tracking of medications and fluids: The nurse meticulously records the dosages of absolutely all administered drugs, including narcotic analgesics and muscle relaxants. The volumes of transfused media are accounted for separately. It is extremely crucial to accurately record the administration time of each medication, as well as the timeline of all surgical stages.
End of surgery: When the surgical intervention is completed, a summary is made in the chart. An exact calculation of the total amount of medications used during anesthesia is performed. At the end of the document, a record regarding the presence or absence of any complications that arose during general anesthesia must be made.
Briefly: answers to topical questions
What parameters are assessed during advanced invasive hemodynamic monitoring?
During advanced hemodynamic monitoring, depending on the sources, the following may be assessed:
- Blood pressure — measured invasively via an arterial line; monitoring mode: continuous.
- Central venous pressure — recorded among homeostasis parameters in the anesthesia chart.
- Pulmonary artery pressure.
- Pulmonary capillary wedge pressure.
- Cardiac output / stroke volume — can be measured by thermodilution or the Fick method.
- Cardiac index.
- Pulmonary vascular resistance.
- Total peripheral vascular resistance.
What instrumental methods exist for monitoring the depth of anesthesia?
For instrumental monitoring of the depth of anesthesia, according to sources, electroencephalography (EEG) may be used.
What gas exchange parameters are controlled using capnography?
During ventilation monitoring, capnography (EtCO2) can be used.
For a comprehensive assessment of ventilation and metabolism, the acid-base balance is examined: pO2, pCO2, pH, BE. The criteria for adequate anesthesia also specify a normal CO2 content.
To assess the adequacy of anesthesia, remember the "Rule of Five D's": Pressure (hemodynamics without surges), Derma (dry skin of normal color), Diuresis (30–50 ml/h), Respiration (normal gas exchange), and Devices (ECG without deviations greater than 20%).
Class and exam questions
How often are pulse and blood pressure measured during routine anesthesia?
During routine anesthesia, blood pressure measurement and pulse counting are performed every 10–15 minutes.
Who needs continuous ECG monitoring during surgery?
Continuous cardiac monitoring is mandatory for patients with concomitant cardiovascular diseases, as well as during thoracic surgeries.
What level of diuresis is considered normal during anesthesia?
Hourly diuresis ranging from 30 to 50 milliliters per hour is considered adequate.
What deviation of parameters from baseline is considered safe?
In anesthesiology, fluctuations in vital signs within 20% of the initial preoperative level are considered acceptable.
What else to study on this topic
- Assessment of acid-base balance (ABB) and interpretation of pO2, pCO2, pH, BE parameters
- Use of EEG to monitor the depth of medically induced sleep
- Pharmacodynamics of narcotic analgesics and muscle relaxants
- Central venous pressure (CVP): measurement technique and clinical significance
- Intraoperative complications: classification and management algorithms
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