1. A past history of allergic reaction, documented by a specialist in Alergology, to a certain substance, especially if the culprit drug is an anaesthetic agent.
2. A past history of clinical manifestations suggestive of allergic reaction to any anaesthetic drug and/or latex.
3. Children with previous multiple surgery, especially spina bifida, myelomeningocele and/or genitourinary malformations (increased risk of allergy to latex).
4. Clinical manifestations suggestive of allergy caused by the intake of avocados, kiwis, banana, chestnuts, apricots, grapes, and pineapple and/or after exposure to objects made of rubber and plastics (risk to allergy to latex).

1. Identification of the allergen product by means of clinical questioning and the performance of specific laboratory tests, such as skin tests, whose specificity and sensitivity is nearly 100%.
2. Avoid contact or exposure to the allergen agent.
3. Start appropriate preoperative medication.
4. Restrict the number of drugs to be administered as much as possible.
   

The performance of specific preoperative tests (skin tests) has no utility in the general population and/or in atopic patients, and should be reserved for patients with documented risk factors. The test results should be given in writing to the patient and should be recorded in the medical history and in the Informed Consent Form signed by the patient prior to the surgery. Even though the ratio risk/benefit should be assessed in all cases, it would be advisable not to delay any type of urgent surgery to perform such tests.

Normal FVC Diminished FEV 1 FEV 1 / FVC < at 70% Diminished FEV 25 – 75% PEF < 400 L/min

Degree of alteration

Mild FEV 1 60 – 79% expected Moderate FEV 1 40 – 59% expected Severe FEV 1 < at 40% expected FEV1 / FVC < at 40% PEF < 150 L/min o < at 30% of the normal theoretical value

TEST BRONCODILATADOR (if FEV1 < 70%)

Administration of β2 agonists (salbutamol – terbutaline) and corticoids (prednisone – prednisolone) Test + if FEV1 increases by 20% and PEF improves

CATEGORY	SYSTOLIC	DIASTOLIC
Normal	< 130	< 85
High limit	130-139	85-89
HYPERTENSION
Mild	140-159	90-99
Moderate	160-179	100-109
Severe	180-209	110-119
Very severe	> 210

Class I. No limitation to physical activity. Class II. Slight limitation to physical activity. Ordinary physical activity does not cause undue fatigue, palpitation, dyspnoea or anginal pain. Class III. Marked limitation to ordinary physical activity. Less than ordinary activity causes the appearance of symptoms. Class IV. Inability to carry on any physical activity without discomfort. Symptoms of heart failure or the anginal syndrome may be present even at rest. If any physical activity is undertaken, discomfort increases.

Class I. Ordinary physical activity (walking, climbing stairs) does not cause anginal symptoms. Development of anginal symptoms with significant activity (prolonged or intense exercise). Class II. Slight limitation to ordinary physical activity. Development of anginal symptoms when walking or climbing stares at a fast pace, after meals or in situations of emotional stress. Class III. Marked limitation to ordinary physical activity. Development of anginal symptoms when walking one or two blocks on a levelled field or when climbing one step. Class IV. Inability to perform any physical activity without discomfort. Possible development of symptoms while at rest.

PERIOPERATIVE CARDIOVASCULAR RISK: clinical predictors

MAJOR - Recent MCI (> at 7 d And/or > at 30 d) - Severe or instable angina (Class III - IV CCS) - Decompensated CCI - Significant arrythmias or severe (Valvulop. AD) IINTERMEDIATE - Acute MCI or moderate angina moderada (Clase II - I CCS) - Decompensated or acute CCI - Diabetes Mellitus MINOR - Uncontrolled HBP - Poor functional capacity - Abnormal ECG (FA - HVI - BRIHH - Abnomal - as ST) Old age

ACC - AHA - Guidelines - Circulation - 1996

The presence of major clinical predictors such as a recent myocardial infarction or decompensated cardiac congestive insufficiency (CCI) may oblige the clinician to delay surgery until the condition at issue has stabilised. Intermediate predictors indicate an increased risk of complications and their presence make it advisable to perform a through examination of the patient, whereas minor predictor, even though they reflect cardiovascular pathology, are not considered on their own as independent predictors of risk.

PERIOPERATIVE CARDIOVASCULAR RISK: TYPE OF SURGERY

HIGH RISK (> 5%) Urgent major surgery, particularly in the elderly Major vascular surgery (aortic) Major vascular peripheral surgery Long duration surgery (<3 hours) associated with important blood loss and/or significant alterations of fluid dynamics INTERMEDIATE RISK (<5%) Carotid surgery Head or neck surgery Intraperitoenal or thoracic surgery Prostate surgery or orthopaedic surgery LOW RISK (<1%) Laparoscopic or superficial surgery

 

Once risks factors have been established, the preoperative assessment should also include the type of drug(s) that the patient has taken or is taking in the 6 months prior to surgery due to the possible drug interactions between the med(s) taken and the drugs used during the anaesthetic procedure. In general terms, the patient should continue to take all drugs, excepting oral anticoagulants (Sintrom), heparin, aspirin, antiaggregants and hypertension ACE inhibitors (angiotensin converting enzyme inhibitors such Captopril, Enalapril) and AIIRAs (angiotensin-II receptor antagonists such as Losartan, Ibesartan) until the day of surgery:

1. Sintrom: It should be withdrawn 3 to 4 days before the surgery and replaced with heparin.
2. Heparin: It should be maintained up to 12 hours before the surgery.
3. Aspirin: It should be withdrawn 7 to 10 before surgery and replaced with ibuprofen or flubiprofen 3 days after the withdrawal up to 12 hours before the surgery.
4. Antiaggregants (antiplatelet agents): ticlopedin (ticlide) must be withdrawn 14 days before surgery, Clopidogrel 7 days before surgery, Abciximab 2 days before and dipiridamol or eptifibatide 24 hours before.
5. ACE inhibitors/ AIIRAs: These drugs should be withdrawn 12 to 24 h before surgery, depending on the drug.

Therefore, if you have or have presented any clinical predictors during the last 6 months or you have a pacemaker and/or are taking any of the medications listed above, you should report it to your surgeon and to your anaesthesiologist who will assess your health status, adjust your medication accordingly and decide the best time for you to undergo your surgery.

 

 

DIABETES AND ANAESTHESIA

Diabetes Mellitus (DM) is one of the most common diseases in surgical patients and its presence is often detected in the preoperative assessment.
DM is characterised by an alteration in the metabolism of carbohydrates secondary to an insufficient activity of the insulin secreted by the pancreas, which gives rise to the development of hyperglycaemia (increased blood sugar levels) and glucosuria (excretion of glucose in the urine).
In accordance with the criteria from the American Society of Diabetes, the diagnosis of diabetes requires at least one of the following conditions:

DIAGNOSTIC CRITERIA FOR DIABETES

Fasting basal glycaemia (at least 8 hours 8h) ≥ at 126 mg/dl (7 mmol/L) confirmed at least on two occasions Random glycaemia ≥ at 200 mg/dl (11,1 mmol/L) accompanied by clinical symptoms characteristics of diabetes Glycaemia ≥ at 200 mg/dl at 2 hours after a 75 gr oral glucose load (tolerance test)

Table 1

The determination of blood glucose (glycaemia/blood sugar) is usually complemented by glycosylated haemoglobin (Hb A1c), the values of which reflect the mean glycaemia values of the patient in the last 4 weeks. This is a very useful parameter to assess the degree of compensation of the diabetes; values > 9% (normal: 5-7%) are indicative of inadequate glycaemic control.

There are two types of Diabetes:

The main differences between both can be appreciated in the following table:

DIFFERENTIAL CHARACTERISTICS BETWEEN BOTH TYPES OF DIABETES

MANIFESTATIONS	TYPE I DIABETES	TYPE II DIABETES
More frequent onset	Infancy or adolescence	Adult age
Insulin production	Very low	Normal to high
Body frame	Thin	Obese
Treatment	Insulin	Diet, OADs, Insulin
Response to insulin	Good	Resistance
Predisposition to ketoacidosis	High	Low
Predominant complications at long term	Microvascular (small vessels)	Macrovascular (large vessels)
Hereditary insufficiency	Moderate	High

Table 2

However, this classification is more theoretical than real, as it is quite usual to find overlapping manifestations of both types of diabetes in daily practice.

The characteristic clinical symptoms of Diabetes includes the so called 4 Ps:

• Polydipsia (excessive thirst)
• Polyfagia (excessive hunger)
• Polyuria (excessive passage of urine)
• Weight loss

In surgical patients with diabetes it is necessary to adopt a series of preoperative measures in order to minimise the development of complications during and/or after the procedure as much as possible:

1. Surgery should be scheduled for early morning.

2. In case of minor surgery, the ingestion of oral food should be stopped between 8 to 12 hours before surgery and in case of major surgery over 12 hours before surgery (dinner time should be changed accordingly the day before the operation).

3. If the patient is on antidiabetic medication, the medication should be adjusted accordingly

• a. Oral antidiabetic agents (OADs): Sulfonylureas and acarboses should be discontinued on the morning of the surgery whilst biguanide agents (Metformin) should be discontinued 48 hours before the surgical procedure.
• b. Delayed-action insulin should be discontinued the night before the procedure and replaced with rapid insulin depending on glycaemic values.
• c. Rapid-action insulin should be maintained at the usual doses subcutaneously and adjusted according to glycaemic values and protocol of the hospital.

4. When fasting starts, the patient is given a sufficient provision of glucose intravenously (150-200 gr/24h) that will be maintained until oral intake is resumed; this provision is started 1 to 2 hours before the procedure begins (for as long as the patient has had dinner).

5. Regular glycaemia controls every 4 hours, the objective of which is to maintain stable glucose values between 100 and 200 mg/dl, thereby avoiding the development of hypoglycaemias.

6. Patients with fasting glycaemia > 140 mg/dl despite treatment should be admitted to the hospital 24 hours before surgery and should receive rapid insulin as per the protocols of the hospital, together with an adequate provision of glucose.

 

 

2) PATHOLOGIES OF ANAESTHETIC RELEVANCE

Apart from their medical interest, there are different pathologies or alterations that are relevant from the point of view of anaesthesia. These conditions make the anaesthetic management of the surgical patients who suffer from these conditions especially complex.

Some of these multiple pathologies that might complicate the anaesthetic procedure include:

As an example, please find below some anaesthesia problems associated with the presence of Rheumatoid arthritis.

Rheumatoid arthritis

Autoimmune disease of unknown origin mainly characterised by an inflammatory chronic status that severely and progressively affects the joints, together with important systemic repercussions.
From an anaesthetic point of view, significant manifestations to be taken into account are:

Deformity, instability and/or decreased mobility of the cervical column and/or temporomandibular joint can seriously complicate orotracheal intubation manoeuvres in cases of general anaesthesia.
In case of significant cervical instability, the presence of neurological compromise should be ruled out before the operation; previous stabilisation of the vertebral column may be required in some patients.
The inflammation of the crycoaryteroid joint (painful swallowing, snoring, stridor) can cause glottic narrowing that will complicate orotracheal intubation and propitiate a laryngeal obstruction following extubation (removal of the orotracheal intubation catheter).

The systemic manifestations to be assessed include pericardial effusion, coronary arthritis or myocarditis, mitral or aortic valvulopathy, pleural effusion and interstitial pulmonary fibrosis, peripheral neuropathies, renal or liver involvement, and dry keratoconjunctivitis (inability to produce tears). The presence of symptoms and signs such as dyspnoea, fatigue, heart murmurs, persistent cough and expectoration, abnormal chest X-ray, paresthesias, or a friction sensation when blinking your eyelashes, are suggestive of significant systemic repercussion. The presence of any of these systemic manifestations may require the implementation of measures prior to the operation (pleural or pericardial effusion), determine the type of anaesthesia to be used (coronary arthritis or myocarditis) and/or the selection of anaesthetic agents (renal or liver involvement).